Processes

15 pages, 2392 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Effect of Biochar Reinforcement on the Wettability, Mechanical, and Thermal Properties of Extrudable Wood–Sodium Silicate Composites

by Sodiq B. Yusuf, Dylan Willard, Michael R. Maughan and Armando G. McDonald

Processes 2026, 14(13), 2094; https://doi.org/10.3390/pr14132094 - 27 Jun 2026

Viewed by 965

Abstract

This original study investigated the effect of biochar (BC) addition, a hydrophobic reinforcing agent, to a thermosetting wood–sodium silicate (W-SS) composite prepared by extrusion for use in additive manufacturing. Commercial BC was blended (10–20% w/w) with W-SS while lowering the [...] Read more.

This original study investigated the effect of biochar (BC) addition, a hydrophobic reinforcing agent, to a thermosetting wood–sodium silicate (W-SS) composite prepared by extrusion for use in additive manufacturing. Commercial BC was blended (10–20% w/w) with W-SS while lowering the SS resin content to form composites. In addition, 50–70% w/w BC-SS composites were also prepared. The flow behavior of the uncured composites was determined by rheometry. The composite mixtures were extruded and cured, and then tested for their flexural, water soak, and thermal properties. Replacing SS content with 10% BC significantly improved the mechanical properties of W-SS while potentially reducing cost and biodegradability; however, 20% w/w BC replacement led to reduced strength. Incorporating BC improved the thermal and dimensional stability of W-SS composites. BC-SS showed improved thermal, hydrophobicity, and flow properties compared to W-SS composites, but lower mechanical properties. It was found that the composite containing 50% W, 10% BC, and 40% SS had an optimum flexural strength of 29 MPa, with thermal property values improving by 29 °C and the dimensional stability improving by 10% compared to 50% W-50% SS (w/w). This implies that BC could help improve the hydrophobicity properties of W-SS while also enhancing mechanical properties, biodegradability, and reducing SS content. 3D printing of the 50% BC-50% SS was demonstrated to showcase the industrial feasibility of printing BC-SS composites. This study demonstrates that BC is an effective additive for enhancing the properties of W-SS composites. Full article

(This article belongs to the Special Issue Processing and Applications of Polymer Composite Materials)

► Show Figures

Graphical abstract

20 pages, 3739 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Dracaena fragrans Extract as a Corrosion Inhibitor for SAE 1025 Steel Used in Aircrafts

by Sury Saday Arizmendi Gómez, María Guadalupe Valladares Cisneros, Víctor Martínez Calzada, Alonso Saldaña Heredia, Jorge Guillermo Alonso Alfaro and Adriana Rodríguez Torres

Processes 2026, 14(13), 2079; https://doi.org/10.3390/pr14132079 - 26 Jun 2026

Viewed by 669

Abstract

This study evaluated the corrosion inhibition performance of Dracaena fragrans extract for SAE 1025 steel in artificial seawater. Inhibition efficiency was assessed using weight loss measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The results showed that inhibition efficiency increased with higher extract [...] Read more.

This study evaluated the corrosion inhibition performance of Dracaena fragrans extract for SAE 1025 steel in artificial seawater. Inhibition efficiency was assessed using weight loss measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The results showed that inhibition efficiency increased with higher extract concentrations, reaching a maximum of 97% at 500 ppm. Potentiodynamic polarization measurements indicated that the extract acts as a mixed-type inhibitor, affecting both anodic and cathodic reactions. EIS analysis revealed an increase in charge transfer resistance and a decrease in double-layer capacitance, confirming the formation of a protective adsorbed film on the steel surface. Adsorption studies indicated that the process followed the Frumkin isotherm and was predominantly governed by physisorption, with a standard Gibbs free energy of adsorption

∆ G_{a d s}^{°}

of approximately −12.33 kJ mol⁻¹. Surface analyses confirmed enhanced protection of the steel substrate in the presence of the extract. Moreover, toxicity tests yielded a germination index (GI) of 35.1% and a relative germination (RG) of 45.6% at 500 ppm. These findings demonstrate the potential of Dracaena fragrans extract as an environmentally friendly corrosion inhibitor for steel exposed to chloride-containing environments in marine and aeronautical applications. Full article

(This article belongs to the Special Issue Modeling, Simulation, and Optimization of Fluids, Materials, and Thermo-Mechanical Systems for Emerging Engineering Applications)

► Show Figures

Graphical abstract

19 pages, 10473 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Impact of the Secondary Air System Compressor on the Performance of a Pressure Gain Combustion Gas Turbine

by Antonio Giuffrida, Alberto Valsecchi and Paolo Chiesa

Processes 2026, 14(13), 2043; https://doi.org/10.3390/pr14132043 - 24 Jun 2026

Viewed by 651

Abstract

Detonation-based combustion systems for application in gas turbines (GTs) have received growing attention in recent decades. Such a technology leads to higher thermodynamic cycle efficiency compared to the conventional deflagrative solution as a result of pressure rise occurring during the heat addition process. [...] Read more.

Detonation-based combustion systems for application in gas turbines (GTs) have received growing attention in recent decades. Such a technology leads to higher thermodynamic cycle efficiency compared to the conventional deflagrative solution as a result of pressure rise occurring during the heat addition process. This study aims to implement pressure gain combustion (PGC) into a thermodynamic cycle where the main compressor is operated at a lower pressure ratio compared to the Brayton–Joule cycle. In detail, this study focuses on the impact of the secondary air system (SAS) compressor, which is necessary to correctly feed the blade cooling circuits with adequate pressure as well as to deliver high-pressure air for cooling the PGC system. A parametric analysis based on different amounts of cooling air to the PGC system is proposed and discussed. In detail, the power demand by the SAS compressor can be as high as 5–6% of the net PGC GT power output, with maximum demands calculated in the range from 16 to 22 MW for a 335 MW F-class gas turbine. These figures are significant because the higher they are, the greater the risk of reducing the performance advantage introduced by the pressure gain combustion. In addition, the effects of SAS compressor efficiency are investigated and a preliminary assessment of both size and rotational speed of the SAS compressor is proposed as well. Full article

(This article belongs to the Special Issue Fluid Dynamics and Thermodynamic Studies in Gas Turbine)

► Show Figures

Figure 1

12 pages, 749 KB

Open AccessFeature PaperEditor’s ChoiceArticle

The Quality Assessment of Solid Oral Dosage Forms Using Parameters of Thermal Emissivity

by Michał Meisner, Natalia Szarek, Beata Szulc-Musioł and Beata Sarecka-Hujar

Processes 2026, 14(13), 2036; https://doi.org/10.3390/pr14132036 - 23 Jun 2026

Viewed by 281

Abstract

Emissivity is a parameter allowing the assessment of thermal/optical properties of active pharmaceutical ingredients (APIs). ε reflects radiative properties, changes with product aging, and correlates with surface characteristics. This study analyzed the thermal emissivity of commercial tablets—extended-release tablets with metformin hydrochloride (from two [...] Read more.

Emissivity is a parameter allowing the assessment of thermal/optical properties of active pharmaceutical ingredients (APIs). ε reflects radiative properties, changes with product aging, and correlates with surface characteristics. This study analyzed the thermal emissivity of commercial tablets—extended-release tablets with metformin hydrochloride (from two manufacturers: XR I and XR II), coated (Co) tablets with ibuprofen, and chewable (Ch) tablets with sodium aluminum dihydroxycarbonate—and compared unexpired vs. expired products. We used the ET 100 emissometer (Surface Optics Corporation, USA; IR range 1.5–21 µm) to measure directional–hemispherical reflectance (DHR) at 300 K, and on the basis of these values, directional thermal emissivity at 20° (DTE20) and 60° (DTE60) and hemispherical thermal emissivity (HTE) were calculated. Then, emissivity parameters were evaluated at 500 K, 800 K, and 1200 K. The DHR values at a 60° angle differed between unexpired and expired XR II tablets across all spectral bands and for XR I tablets, except in the 3.0–4.0 micron range. In turn, for DHR at 20°, high effect sizes were demonstrated between unexpired and expired Ch tablets for 1.5–2.0, 2.0–3.5, 4.0–5.0, and 5.0–10.5 microns. For the DHR at 60°, the high effect size between unexpired and expired Ch tablets was found at 1.5–2.0, 2.0–3.5, and 4.0–5.0 microns. At 300 K, XR I and XR II tablets showed comparable DTE20, DTE60, and HTE. The Ch tablets had higher DTE20 than XR I and XR II (0.968 vs. 0.954 and 0.958, respectively; p < 0.001) and Co tablets (0.968 vs. 0.930; p < 0.001). The Co tablets had the highest DTE60 mean values (0.941 vs. 0.926 for Ch, p < 0.001; 0.926 for XR I, p < 0.001; 0.932 for XR II, p = 0.001). The HTE value was the highest for Ch tablets (p < 0.001 vs. others). During thermal modeling of the emissivity parameters, all DTE20, DTE60, and HTE values decreased with temperature, reaching their lowest values at 1200 K. The largest relative decrease in HTE values (over 15%) between the standard measurement temperature of 300 K and the modeled temperature of 1200 K was found for Ch tablets. Tablets with different release profiles show distinct DTE20, DTE60, and HTE values, suggesting that emissivity may serve as a rapid, non-destructive screening tool that could support further pharmaceutical evaluation during storage. However, emissivity alone does not establish pharmaceutical quality, and the present findings should be interpreted as proof-of-concept rather than as validation of a stand-alone quality-control method. Full article

(This article belongs to the Section Chemical Processes and Systems)

► Show Figures

Figure 1

13 pages, 3296 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Structural, Thermal, Optical and Dielectric Properties of New Synthesized Keggin-Type Lacunary Polyoxometalates Cs₅PMMo₁₁(H₂O)O₃₉ (M = Cu and Zn)

by Farah Lachquer, Abdellah Benzaouak, Noureddine Touach, Abdallah Oulmekki and Jamil Toyir

Processes 2026, 14(12), 1928; https://doi.org/10.3390/pr14121928 - 13 Jun 2026

Viewed by 387

Abstract

New lacunary Keggin-type polyoxometalate salts with the formula Cs₅PMMo₁₁(H₂O)O₃₉ (M = Cu, Zn) were synthesized via the inorganic solution condensation method. X-ray diffraction and FT-IR spectroscopy confirmed the preservation of the Keggin structure. The surface morphology [...] Read more.

New lacunary Keggin-type polyoxometalate salts with the formula Cs₅PMMo₁₁(H₂O)O₃₉ (M = Cu, Zn) were synthesized via the inorganic solution condensation method. X-ray diffraction and FT-IR spectroscopy confirmed the preservation of the Keggin structure. The surface morphology and elemental composition were characterized using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. Thermal analysis, performed by differential scanning calorimetry coupled with thermogravimetry, demonstrated a significant enhancement in thermal stability upon the incorporation of the transition metals into the heteropolyacid framework. Specifically, the substitution of protons by cesium and of molybdenum by copper or zinc positively influenced the crystallographic configuration of the salts, raising their thermal resistance (up to 526 °C). Furthermore, optical and dielectric measurements revealed promising electronic properties in the synthesized lacunary salts. Notably, the compound Cs₅PZnMo₁₁(H₂O)O₃₉ exhibited a substantially increased dielectric constant at low frequency, underscoring the synergistic effect of zinc addition on its dielectric performance. Full article

(This article belongs to the Special Issue Preparation, Synthesis and Chemical Properties of Functional Materials)

► Show Figures

Figure 1

20 pages, 3442 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Constraint-Based Disassembly Sequencing Algorithms for Dismantling Applications—A Comparative Study

by Aron Webster, Adam Knight and Xiaodong Jia

Processes 2026, 14(12), 1937; https://doi.org/10.3390/pr14121937 - 13 Jun 2026

Viewed by 441

Abstract

With growing interest in automated dismantling operations for hazardous environments, automatically planning safe and efficient disassembly sequences is becoming increasingly important. When a large structure is segmented into parts, the removal order must ensure that each part can be extracted safely without destabilising [...] Read more.

With growing interest in automated dismantling operations for hazardous environments, automatically planning safe and efficient disassembly sequences is becoming increasingly important. When a large structure is segmented into parts, the removal order must ensure that each part can be extracted safely without destabilising the remaining structure. This paper presents a comparative study of four algorithms for solving the disassembly sequencing problem in two dimensions: First Feasible Random Search (FFRS), Greedy Search (GS), Height-Decreasing Search (HDS), and Stochastic Tree Search (STS). The present study focuses specifically on sequencing feasibility under geometric and physical constraints, namely connectivity, accessibility, and structural stability. The 2D formulation provides a simplified yet computationally efficient testbed for analysing algorithmic behaviour under varying cutting complexities, with the objective of minimising the total removal trajectory length. Results show that while STS consistently finds optimal or near-optimal solutions, its factorial runtime limits scalability. GS produces high-quality solutions efficiently but can become trapped in infeasible configurations, whereas HDS offers strong reliability and speed at the expense of solution quality. Based on these findings, a hybrid height-based backtracking algorithm is proposed as a promising future direction, combining the efficiency of greedy search with the robustness of stochastic exploration. The results provide insight into the relative strengths and limitations of different sequencing strategies and establish a foundation for future extension to more realistic dismantling scenarios, including 3D and radiologically constrained applications. Full article

(This article belongs to the Section Particle Processes)

► Show Figures

Graphical abstract

16 pages, 1160 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Improvement and Simulation of a Dairy Wastewater-Based Bioprocess: From Cheese Whey to Lactic Acid and Probiotic Microbial Biomass

by Daniel Tobías-Soria, Kevin Francisco Chacón-García, Samuel Pérez-Vega, Nestor Gutierrez-Mendez, Sergio Cisneros de la Cueva and Ivan Salmerón

Processes 2026, 14(12), 1880; https://doi.org/10.3390/pr14121880 - 10 Jun 2026

Viewed by 473

Abstract

In Mexico, cheese whey (CW) is commonly treated as a dairy wastewater despite its high lactose and nutrient content. This study evaluated cheese whey (CW) and ultrafiltered cheese whey (UF-CW) as low-cost substrates for the cultivation of the probiotic strains Lactobacillus acidophilus and [...] Read more.

In Mexico, cheese whey (CW) is commonly treated as a dairy wastewater despite its high lactose and nutrient content. This study evaluated cheese whey (CW) and ultrafiltered cheese whey (UF-CW) as low-cost substrates for the cultivation of the probiotic strains Lactobacillus acidophilus and Lactococcus lactis. The proposed bioprocess simultaneously enables the production of probiotic biomass and lactic acid, a high-value platform chemical with broad applications in the food, pharmaceutical, and biopolymer industries. In the first experimental trials, in which CW and UF-CW were used solely as media, fermentations lasted 36 h at 30 and 37 °C, with initial pH levels of 5 and 7. CW demonstrated a greater capacity to support the growth of lactic acid bacteria. Thus, to increase the fermentative capability of UF-CW, it was supplemented with yeast extract (YE) or corn steep liquor (CSL), and CaCO₃ was added to stabilize pH, as low pH values inhibit growth and lactic acid production. The proposed strategy notably improved microbial growth in UF-CW, increasing Lc. lactis and L. acidophilus populations from 8.3 and 8.2 Log₁₀ CFU/mL to 9.3 Log₁₀ CFU/mL, respectively. The findings suggest that dairy wastewater can be effectively repurposed as a low-cost cultivation medium for these bacteria. ASPEN simulation analyses demonstrated that lactose conversion efficiency and final product concentration were key factors affecting process performance and economic feasibility. Among the evaluated scenarios, a 45% lactose-to-lactic acid conversion yielded the most economically favorable process performance compared with conversions of 10% and 25%. Future research should focus on enhancing fermentation yields and adopting more efficient downstream recovery techniques. Full article

(This article belongs to the Special Issue Recent Advances in Bioprocess Engineering and Fermentation Technology)

► Show Figures

Graphical abstract

22 pages, 5029 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Evaluation of Catalytic Biomass–Clay Interactions on Co-Combustion Kinetics and Thermodynamics Using Integral Coats–Redfern Model-Fitting and Flynn–Wall–Ozawa Model-Free Analysis

by Russell C. Smith and M. Toufiq Reza

Processes 2026, 14(11), 1819; https://doi.org/10.3390/pr14111819 - 4 Jun 2026

Viewed by 539

Abstract

This study investigated the co-combustion behavior of loblolly pine (LP100), kaolin clay (KC100), and LP-KC blends (LP75KC25, LP50KC50, and LP25KC75) using thermogravimetric analysis under air gas flow at heating rates of 5, 10, and 20 °C min⁻¹. The objective was to [...] Read more.

This study investigated the co-combustion behavior of loblolly pine (LP100), kaolin clay (KC100), and LP-KC blends (LP75KC25, LP50KC50, and LP25KC75) using thermogravimetric analysis under air gas flow at heating rates of 5, 10, and 20 °C min⁻¹. The objective was to evaluate how biomass–mineral blending affects thermal degradation, reaction-stage development, kinetic behavior, and thermodynamic properties. The TGA-DTG results were interpreted using Coats–Redfern model-fitting kinetics, Flynn–Wall–Ozawa (FWO) model-free kinetics, and thermodynamic analysis. LP100 and LP-KC blends exhibited two main stages: Phase II oxidative devolatilization and Phase III char oxidation with overlapping kaolinite dehydroxylation, while KC100 showed one dominant high-temperature mineral transformation. In Phase III, the blends’ DTG peak temperatures ranged from 401.7 to 474.3 °C at 5 °C min⁻¹, 427.0 to 500.3 °C at 10 °C min⁻¹, and 478.3 to 509.0 °C at 20 °C min⁻¹. Coats–Redfern Ea values were 58.16–70.50 kJ mol⁻¹ for LP100 in Phase III, and 178.85–181.59 kJ mol⁻¹ for KC100 in Phase III, while the blends’ Ea values ranged from 24.07 to 81.31 kJ mol⁻¹ in Phase II and 30.00 to 59.59 kJ mol⁻¹ in Phase III. FWO analysis confirmed conversion-dependent Ea behavior, with KC100 showing the highest energy barrier. Thermodynamic analysis showed positive ∆G values of 170.59–188.34 kJ mol⁻¹ in Phase II and 197.38–240.84 kJ mol⁻¹ in Phase III. ∆H ranged from 19.67 to 76.55 kJ mol⁻¹ in Phase II and reached 172.53–175.43 kJ mol⁻¹ for KC100 in Phase III, while negative ∆S values of −0.07 to −0.28 kJ mol⁻¹ K⁻¹ indicated ordered activated complexes. In conclusion, LP lowered the apparent kinetic and thermodynamic barriers of KC transformation during co-combustion. Full article

(This article belongs to the Special Issue Advanced Catalytic Materials for Oxidation and Reduction Processes in Environmental Systems)

► Show Figures

Figure 1

29 pages, 14977 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Why Is Offshore Gas-to-Wire with CCUS Geopolitically and Economically Critical to Decarbonization?

by Icaro B. Boa Morte, Israel Bernardo S. Poblete, Cláudia R. V. Morgado, José Luiz de Medeiros and Ofélia de Queiroz Fernandes Araújo

Processes 2026, 14(11), 1791; https://doi.org/10.3390/pr14111791 - 30 May 2026

Viewed by 549

Abstract

Carbon taxes and credits (CT&C) accelerate global deployment of carbon capture, utilization and storage (CCUS) technologies to enable energy transition. This study investigates the economic performance and resilience of floating gas-to-wire with CCUS (f-GTW-CCUS), deployed at the wellhead of stranded CO₂-rich [...] Read more.

Carbon taxes and credits (CT&C) accelerate global deployment of carbon capture, utilization and storage (CCUS) technologies to enable energy transition. This study investigates the economic performance and resilience of floating gas-to-wire with CCUS (f-GTW-CCUS), deployed at the wellhead of stranded CO₂-rich offshore oil and gas reservoirs. The f-GTW-CCUS platform integrates a natural gas combined cycle power plant with monoethanolamine post-combustion capture (PCC-MEA), producing low-carbon electricity (23 kgCO_2e/MWh, competitive with renewables) while monetizing captured CO₂ via enhanced oil recovery (EOR). The mass and energy balance data from the proposed process configuration were obtained in the literature. Critically, f-GTW-CCUS operates on wellhead-sourced in situ-associated gas, eliminating exposure to volatile natural gas markets, and achieves a levelized cost of electricity (LCOE) of USD 67.15/MWh. Monte Carlo analysis (10,000 Gaussian iterations, 30-year lifetime, 10% discount rate, three CT&C scenarios, namely, low/medium/high) is used to quantify economic feasibility across three stochastic variables: oil, natural gas, and electricity prices, starting in the 5th year. The results demonstrate the following: (1) Case A (f-GTW without CCUS) remains economically infeasible (NPV < 0) under all price volatility scenarios due to insufficient electricity-only revenue and carbon taxation penalties; (2) Case B (f-GTW-CCUS with immediate CCUS deployment) maintains positive NPV across all scenarios, with EOR monetization contributing 43% of total revenue; (3) the critical CCUS deployment-delay threshold is 6 years under high carbon taxation, extending to 10 years when carbon credits are included. Gate-to-gate environmental assessment (carbon intensity, water footprint, land transformation) shows f-GTW-CCUS superiority versus alternative power systems, with minimal water–land nexuses due to offshore desalination. An empirical consistency assessment based on the 2026 geopolitical energy crisis demonstrates the structural resilience of the f-GTW-CCUS plant: the wellhead sourcing provides resilience to global natural gas price shocks, while the concurrent crude price escalation amplifies EOR revenues by 43–57%, improving project feasibility during commodity disruptions. These findings position f-GTW-CCUS as a critical decarbonization pathway for O&G producers exploiting stranded gas reserves. The technology combines carbon intensity reduction with economic resilience under volatile energy market conditions and mandatory climate policies. Full article

(This article belongs to the Special Issue Oil and Gas Drilling Processes: Control and Optimization, 2nd Edition)

► Show Figures

Figure 1

20 pages, 5410 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Sustainable Valorization of Brassica napus: A Circular Approach to Enhance Biomethane Recovery via Electrohydrolysis

by Julio A. Gutiérrez González, Álvaro Ramírez, Javier Llanos, José Villaseñor Camacho and Martín Muñoz-Morales

Processes 2026, 14(11), 1758; https://doi.org/10.3390/pr14111758 - 28 May 2026

Cited by 1 | Viewed by 399

Abstract

The circular valorization of biomass for sustainable energy recovery is a strategic priority in the transition toward low-carbon systems. In the last decade, anaerobic digestion (AD) has emerged as an efficient technology to produce an energetic vector to replace natural gas with biomethane [...] Read more.

The circular valorization of biomass for sustainable energy recovery is a strategic priority in the transition toward low-carbon systems. In the last decade, anaerobic digestion (AD) has emerged as an efficient technology to produce an energetic vector to replace natural gas with biomethane and reduce waste; however, the hydrolysis of refractory fractions remains the main rate-limiting step. This study investigates an innovative electro-assisted pretreatment of biomass to promote the first rate-limiting hydrolysis step of refractory compounds in biomethane production. Lignocellulosic residues are employed not only as feedstock for the AD process but also as substrates in electrohydrolysis (EH) pretreatment using an Ir-Ta mixed metal oxide (MMO) anode coupled with advanced biomass-derived carbon felt cathodes. Two cathodes were functionalized with Phragmites Australis (PhA) hydrochars, untreated (PA) and KOH-activated (PA-KOH), to enhance the in situ generation of reactive oxygen species (ROS). Brassica napus (Bn) was chosen as the other biomass selected as a feedstock of AD, and was subjected to EH at varying energy inputs (500–5000 kJ kg⁻¹), evaluating structural and biochemical shifts. The results demonstrate that EH effectively modifies the biomass matrix; the PA-KOH-CF cathode exhibited good selectivity to degrade lignocellulosic structures, but higher biomethane production was achieved at 2500 kJ·kg⁻¹ TS using PA-CF, reaching an increase of 52% compared with untreated samples. Kinetic analysis of the biomethane potential was performed using the modified Gompertz model. The model accurately captured the asymmetric sigmoidal transitions of methane production with different electrode configurations, and finally, energy balance assessment identified 2500 kJ·kg⁻¹ TS as the optimal operational threshold. These findings suggest that an excess of applied energy is critical to the availability of soluble organic matter and the presence of refractory compounds that reduce efficiency. This electro-assisted approach offers a robust strategy for intensifying AD, aligning with circular bioenergy objectives. Full article

(This article belongs to the Special Issue Research Trends in Electrochemical Technology for Sustainable Environmental Applications)

► Show Figures

Figure 1

18 pages, 1924 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Impact of Physical, Chemical, Biological, and Thermal Pretreatments on the Hydrolysis and Solubilization of TWAS Under Anaerobic Conditions

by Maha Dassouki Dit Tahan, Nada Hosni, Meagan Morrow, Abir Hamze, Meni Mancini, Dimitris Chrysochoou and Elsayed Elbeshbishy

Processes 2026, 14(11), 1773; https://doi.org/10.3390/pr14111773 - 28 May 2026

Viewed by 1355

Abstract

Anaerobic digestion (AD) of thickened waste-activated sludge (TWAS) is widely applied for sludge stabilization and renewable energy recovery; however, hydrolysis of complex organics often limits fermentation performance. This study evaluated the effects of multiple pretreatment strategies on solubilization, volatile fatty acids (VFAs) production, [...] Read more.

Anaerobic digestion (AD) of thickened waste-activated sludge (TWAS) is widely applied for sludge stabilization and renewable energy recovery; however, hydrolysis of complex organics often limits fermentation performance. This study evaluated the effects of multiple pretreatment strategies on solubilization, volatile fatty acids (VFAs) production, and extracellular polymeric substances (EPS) during 80 h mesophilic batch fermentation. Pretreatments included hydrothermal treatment (HTP; 70, 90, and 170 °C), ultrasonication (US; 3000, 5000, and 10,000 KJ/kg TS), chemical pretreatment (acidic pH 4 and alkaline pH 10), and biological augmentation using YDRO Process^® (YDRO^®; 5%, 10%, 15% v/v). Across feedstock pretreatments, HTP generated the greatest improvements in solubilization, increasing SCOD by 56–113-fold and producing substantial acetate levels, particularly at 70 °C, alongside substantial phosphorus release. Ultrasonication resulted in moderate solubilization (28–56-fold) and elevated soluble phosphorus and ammonia. Acidic pretreatment maximized soluble phosphorus, but showed limited VFAs production, whereas alkaline pretreatment rapidly increased soluble EPS due to pH-induced cell disruption. Bioaugmentation achieved the highest total COD but yielded comparatively low soluble fractions. Following fermentation, HTP 170 °C consistently outperformed other treatments, maintaining elevated soluble COD and producing the highest acetate concentration. EPS analysis revealed extensive protein and polysaccharide degradation in thermal and bioaugmented systems, indicating active utilization during fermentation. Overall, the results demonstrate that targeted pretreatment strategies significantly enhance organic solubilization, EPS disruption, and VFAs yields, with thermal pretreatment showing the greatest potential to accelerate hydrolysis and acidogenesis. These findings provide valuable insights for optimizing the pre-methanogenic stages of AD and improving the efficiency of sludge treatment and resource recovery. Full article

(This article belongs to the Special Issue Advanced Biofuel Production Processes and Technologies)

► Show Figures

Graphical abstract

20 pages, 4126 KB

Open AccessFeature PaperEditor’s ChoiceArticle

A Cashew Nut-Based Fermented Beverage: Development, Characterization, Potential Functionality and Sensory Evaluation

by Rita Sannara Bandeira do Nascimento, Brenda Novais Santos, Ana Lúcia Fernandes Pereira and Sueli Rodrigues

Processes 2026, 14(11), 1756; https://doi.org/10.3390/pr14111756 - 28 May 2026

Viewed by 466

Abstract

The demand for functional foods, particularly probiotics, has increased substantially in recent years. The search for plant-based milk alternatives (PBMA) has also risen, influenced by factors such as lactose intolerance, allergies, veganism, and environmental sustainability. Cashew nut kernels have high nutritional value, and [...] Read more.

The demand for functional foods, particularly probiotics, has increased substantially in recent years. The search for plant-based milk alternatives (PBMA) has also risen, influenced by factors such as lactose intolerance, allergies, veganism, and environmental sustainability. Cashew nut kernels have high nutritional value, and are a suitable alternative for preparing plant-based beverages. Therefore, this study aimed to develop a potentially probiotic cashew nut-based beverage fermented by Lacticaseibacillus casei NRRL B-442. The fermented cashew nut-based beverage was prepared, and its stability was evaluated over a 42-day refrigerated storage period (4 °C). Various parameters were monitored, including pH, viability, and concentration of lactic acid, in addition to sugars. The survival rate of microorganisms following simulated gastrointestinal digestion was also determined. Sensory analysis included word association, hedonic scale, and CATA tests. During fermentation, the microorganism consumed glucose, leading to the production of lactic acid. The fermented drink was stable throughout the refrigerated storage period, with a final viable cell count greater than 12 log CFU/mL. After in vitro digestion, probiotic survival rates were higher than 73% in all the samples analyzed. The sensory analysis showed positive consumer acceptance. No statistically significant difference in overall hedonic acceptance was observed between the CNB sweetened with sucrose and sucralose, although both differed from the commercial fermented milk control in several sensory attributes. These results suggest that the cashew nut-based matrix is a promising alternative for developing functional plant products. This study effectively produced a probiotic beverage from cashew nut kernels with functional potential, providing a new product option for interested consumers. Full article

(This article belongs to the Section Food Process Engineering)

► Show Figures

Figure 1

22 pages, 1142 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Stability of Individual Phenolic Compounds and Antioxidant Activity During Storage of a Syrah Grape Seed Extract

by Pamela Georgieva, Yavor Ivanov, Zlatina Chengolova, Gjore Nakov and Tzonka Godjevargova

Processes 2026, 14(11), 1721; https://doi.org/10.3390/pr14111721 - 26 May 2026

Cited by 1 | Viewed by 1169

Abstract

The valorization of winery by-products is a sustainable strategy for receiving valuable bioactive compounds. The aim of this study was to obtain Syrah grape seed extract and investigate the stability of extract phenolic compounds and antioxidant capacity. Separated grape seeds from grape pomace [...] Read more.

The valorization of winery by-products is a sustainable strategy for receiving valuable bioactive compounds. The aim of this study was to obtain Syrah grape seed extract and investigate the stability of extract phenolic compounds and antioxidant capacity. Separated grape seeds from grape pomace were dried under two different conditions: 23 °C for 10 days and 40 °C for 24 h. Polyphenols were extracted from the dried seeds using 70% aqueous ethanol under magnetic stirring at 600 rpm for 3 h. The yield, color, nutrition value, and mineral contents of the extract were determined. The obtained extracts from the seeds dried at different temperatures were concentrated using a vacuum evaporator. The concentrate was subsequently divided into three forms: liquid, lyophilized, and dried at 40 °C. The individual phenolic components of the lyophilized grape seed extract were determined by HPLC. All extracts were stored at 4 °C and 23 °C for 10 months. The effect of the grape seed drying conditions, extract forms, storage temperature, and time on the total phenolic content, total flavonoids, procyanidins, and antioxidant capacity of the extracts was investigated. Changes in these parameters were evaluated at 0, 3, 6, and 10 months of storage. Degradation kinetics on the basis of antioxidant activity during extracts storage were calculated. Additionally, the individual phenolic composition of liquid and lyophilized Syrah grape seed extracts stored for 10 months was determined by HPLC. The degradation degree of the individual compounds in the extracts was calculated. Full article

(This article belongs to the Special Issue Emerging Technologies for the Valorization of Agro-Food Byproducts into Functional Ingredients and Foods)

► Show Figures

Figure 1

15 pages, 2088 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Machine Learning-Guided Electrochemical Fingerprinting for Rapid Polyethylene Microplastic Detection in Seawater and Seafood Matrices

by Kundan Kumar Mishra, Akash Kumar, Aditya Karthik Sriram, Sriram Muthukumar and Shalini Prasad

Processes 2026, 14(11), 1690; https://doi.org/10.3390/pr14111690 - 23 May 2026

Cited by 4 | Viewed by 651

Abstract

Polyethylene (PE) microplastics are increasingly recognized as a critical environmental and food-safety concern; however, routine monitoring remains limited by conventional methods that are labor-intensive, time-consuming, and difficult to translate into rapid, on-site screening. Here, we report a machine learning-guided electrochemical fingerprinting platform for [...] Read more.

Polyethylene (PE) microplastics are increasingly recognized as a critical environmental and food-safety concern; however, routine monitoring remains limited by conventional methods that are labor-intensive, time-consuming, and difficult to translate into rapid, on-site screening. Here, we report a machine learning-guided electrochemical fingerprinting platform for rapid PE microplastic detection using a chitosan–PE interfacial film coupled with electrochemical impedance spectroscopy (EIS) and coulometry. The platform generated concentration-dependent electrical fingerprints in artificial ocean water, captured through Bode, Nyquist, and charge–time responses. Quantification was achieved across 1–256 ng/mL with strong linearity (R² = 0.976) and an ultralow LoD of 0.1 ng/mL, demonstrating high analytical sensitivity. Practical applicability was validated through spike–recovery in ocean water (R² = 0.967) and shrimp-derived matrices with matrix-matched normalization, yielding recoveries of 90–105% across low, mid, and high spike levels. Under the tested particle set, PE produced stronger responses than non-target polypropylene (PP) and polystyrene (PS), supporting empirical polymer discrimination. Machine learning classification using impedance-derived features achieved an AUC = 0.98, with 100% correct identification of Low and 95.24% correct identification of High samples. Overall, this electrochemical–ML framework enables rapid, sensitive, and matrix-tolerant PE microplastic screening in environmental water and seafood-related matrices, offering a promising pathway toward portable microplastic monitoring. Full article

(This article belongs to the Special Issue Electrochemical Sensors for Environmental and Food Sample Detection)

► Show Figures

Graphical abstract

13 pages, 2058 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Synergistic Resource Utilization of Carbon Dioxide-Rich Off-Gas and Industrial By-Product Alkaline Salt

by Guodong Yao, Qiuxia Zhu, Limin Jin, Ningzheng Zhu, Yangyuan Zhou and Jianfu Zhao

Processes 2026, 14(10), 1565; https://doi.org/10.3390/pr14101565 - 12 May 2026

Viewed by 365

Abstract

The capture and utilization of carbon dioxide (CO₂) from CO₂-rich off-gas streams play a vital role in mitigating carbon emissions. Chemical absorption, as a well-established and commercially deployed CO₂ capture technology, has attracted sustained research interest. Current efforts [...] Read more.

The capture and utilization of carbon dioxide (CO₂) from CO₂-rich off-gas streams play a vital role in mitigating carbon emissions. Chemical absorption, as a well-established and commercially deployed CO₂ capture technology, has attracted sustained research interest. Current efforts in this field are primarily directed toward developing cost-effective absorbents and energy-efficient processes. Meanwhile, industrial operations generate significant quantities of by-product alkaline salts, which often consist of mixtures containing two or more components such as sodium carbonate, sodium hydroxide, sodium sulfate, and sodium chloride. The use of these alkaline by-products for CO₂ absorption to produce value-added chemicals presents a promising and economically attractive carbon capture and utilization (CCU) strategy. In this work, an industrial salt by-product from a petrochemical plant, rich in sodium carbonate and sodium sulfate, was employed as an absorbent to simulate a CCU process. By controlling the mass transfer and crystallization behavior of CO₂ within the multicomponent system during carbon capture, it was feasible to produce sodium bicarbonate from CO₂. Concurrently, industrial-grade sodium sulfate was separated based on solubility differences. This study proposes an innovative integrated approach that combines the utilization of alkaline by-product salts, CO₂ capture from off-gas, and resource recovery in a single process. Full article

(This article belongs to the Special Issue Advances and Innovative Solutions in CCUS Engineering: Carbon Capture, Utilization, and Storage)

► Show Figures

Figure 1

28 pages, 3528 KB

Open AccessFeature PaperEditor’s ChoiceArticle

When More CO₂ Utilization Is Not Better: Life Cycle Assessment of Trade-Offs and Optimal Design in Plastic Waste-to-Hydrogen Systems

by Yuchan Ahn

Processes 2026, 14(10), 1543; https://doi.org/10.3390/pr14101543 - 10 May 2026

Viewed by 484

Abstract

This study presents an integrated environmental assessment of plastic waste-to-hydrogen systems with varying CO₂ utilization ratios, combining process-level simulation with life-cycle assessment (LCA). The environmental impacts are evaluated across key categories, including global warming potential (GWP), fine particulate matter formation (PM), fossil [...] Read more.

This study presents an integrated environmental assessment of plastic waste-to-hydrogen systems with varying CO₂ utilization ratios, combining process-level simulation with life-cycle assessment (LCA). The environmental impacts are evaluated across key categories, including global warming potential (GWP), fine particulate matter formation (PM), fossil resource scarcity (FRC), and water consumption (WC). The results reveal a non-linear relationship between CO₂ utilization and environmental impacts. As the CO₂ utilization ratio increases from the N₂ baseline to moderate levels (CO₂-40 to CO₂-50), environmental impacts decrease due to improved carbon utilization and reduced direct CO₂ emissions. However, further increases in CO₂ utilization lead to a reversal of this trend, with environmental burdens rising significantly due to increased energy and utility demand associated with intensified CO₂ recycling. Process contribution analysis shows that the dominant impact drivers shift from direct CO₂ emissions to utility-related contributions, particularly heat (steam) and electricity, at higher utilization levels. A trade-off analysis between direct CO₂ emissions and utility-related impacts identifies an optimal environmental operating range around CO₂-50. An integrated comparison with techno-economic performance, represented by the minimum hydrogen selling price (MHSP), reveals a divergence between environmental and economic optima. While environmental impacts are minimized at CO₂-40 to CO₂-50, the economic optimum occurs at higher utilization levels (CO₂-60 to CO₂-70). These results highlight that CO₂ utilization acts as a key design variable governing the trade-off between carbon efficiency and energy demand. An optimal compromise region is identified around CO₂-50 to CO₂-60, providing a balanced operating window for both environmental and economic performance. This study demonstrates that maximizing CO₂ utilization is not necessarily optimal from a system-level sustainability perspective and provides practical insights for the design and optimization of integrated plastic waste-to-hydrogen systems. Full article

(This article belongs to the Special Issue Green Process Engineering for the Conversion of Waste Carbon Sources into High-Value Chemicals)

► Show Figures

Figure 1

33 pages, 3735 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Artificial Neural Network-Based Classification of Industrial Sustainability Profiles for Differentiated Fiscal Policy Design in Remanufacturing Processes

by Marta Lilia Eraña-Díaz, Juana Enríquez-Urbano, Beatriz Martínez-Bahena, Jazmin Yanel Juárez-Chávez, Alfonso D’Granda-Trejo and Javier De-la-Rosa-Mondragon

Processes 2026, 14(9), 1501; https://doi.org/10.3390/pr14091501 - 6 May 2026

Viewed by 819

Abstract

The design of differentiated fiscal instruments for industrial sustainability requires robust, data-driven tools capable of capturing the heterogeneity of environmental performance across manufacturing units—a challenge that conventional econometric approaches address only partially, given the non-linear nature of operational–environmental interactions in reconfigurable production systems. [...] Read more.

The design of differentiated fiscal instruments for industrial sustainability requires robust, data-driven tools capable of capturing the heterogeneity of environmental performance across manufacturing units—a challenge that conventional econometric approaches address only partially, given the non-linear nature of operational–environmental interactions in reconfigurable production systems. This study introduces a two-phase computational framework that integrates unsupervised machine learning and supervised classification to generate evidence-based sustainability profiles for fiscal policy targeting. Its principal contribution is the combination of K-Means clustering with a binary artificial neural network (ANN) classifier, operationalized through an accessible decision-support interface that enables differentiated incentive allocation without requiring programming expertise from policymakers. A dataset of 1000 manufacturing records comprising seven operational and technological input variables—material usage, production capacity, reconfiguration time, downtime, AI optimization, IoT connectivity, and predictive maintenance—and three environmental output indicators—energy consumption, carbon emissions, and waste generation—was analyzed. In Phase One, K-Means segmentation with k = 6, selected through multi-criteria convergence (Silhouette = 0.102; Elbow, Davies–Bouldin, and Calinski–Harabasz indices), identified six distinct sustainability profiles with marked environmental differentiation. In Phase Two, a binary ANN classifier (architecture: 7 → 64 → 32 → 1 neurons; ReLU and sigmoid activations) was trained to distinguish the reference cluster C0 (low environmental impact: energy 145.1 kWh, emissions 45.2 CO₂-eq) from the high-impact cluster C1 (emissions 67.8 CO₂-eq, waste 41.5 kg). The trained classifier achieved an overall accuracy of 75.4% and an AUC-ROC of 0.774 on the held-out test set, with a macro-averaged F1-score of 0.753 and a Cohen’s kappa coefficient of 0.508, indicating moderate-to-substantial agreement beyond chance. Class C1 (high-impact establishments) achieved a precision of 0.794 and a recall of 0.730, supporting reliable identification of manufacturing units that would most benefit from targeted fiscal support. The framework is deployed through a Gradio-based graphical interface incorporating a traffic-light sustainability classification (green/yellow/red), enabling direct and interactive application by tax authorities and industrial policymakers. The modular architecture supports adaptation to larger or sector-specific datasets, making it transferable across industrial policy contexts. Full article

(This article belongs to the Special Issue Thermal Engineering: Energy Conversion, Numerical Simulation, and Advanced Control)

► Show Figures

Graphical abstract

17 pages, 1096 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Accelerated Solvent Extraction for Effective Isolation of Sea Fennel Phenolic Antioxidants and Antimicrobials

by Petra Brzović, Sanja Radman, Danijela Skroza and Ivana Generalić Mekinić

Processes 2026, 14(9), 1459; https://doi.org/10.3390/pr14091459 - 30 Apr 2026

Cited by 1 | Viewed by 444

Abstract

Sea fennel is a halophyte plant recognised as a valuable source of phenolics with good antioxidant and antimicrobial potential. In this study, accelerated solvent extraction (ASE) was optimised to improve the recovery of phenolic compounds from sea fennel, particularly hydroxycinnamic acids, which are [...] Read more.

Sea fennel is a halophyte plant recognised as a valuable source of phenolics with good antioxidant and antimicrobial potential. In this study, accelerated solvent extraction (ASE) was optimised to improve the recovery of phenolic compounds from sea fennel, particularly hydroxycinnamic acids, which are known to be dominant. The effect of the applied extraction temperature (20–120 °C) and used solvent (20–80% hydroethanolic mixtures) on total phenolic content (TPC) was systematically evaluated. Individual phenolic composition, antioxidant activity, and antimicrobial properties were measured in the top four samples. TPC was determined spectrophotometrically, while individual compounds were analysed by chromatography. Antioxidant (reducing and free-radical scavenging) activity was assessed using three assays, while the minimum inhibitory concentrations and minimum bactericidal concentrations were determined using the microdilution method against five bacterial strains. Both temperature and solvent composition significantly influenced phenolic extraction efficiency. The highest TPC and concentrations of chlorogenic acid and its derivatives were obtained at 60 °C using 60–80% ethanol (664 and 673 mg of gallic acid equivalents/g of dry extract), while higher temperatures generally resulted in reduced phenolic yield. Extracts obtained under optimal ASE conditions exhibited enhanced antioxidant activity and moderate antimicrobial effects, particularly against Gram-positive bacteria, which demonstrates that accelerated solvent extraction represents an efficient approach for obtaining sea fennel extracts rich in valuable bioactives with potential use in different industries. Full article

(This article belongs to the Special Issue Analysis and Processes of Bioactive Components in Natural Products)

► Show Figures

Figure 1

17 pages, 16329 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Binderless Hardwood Tree Bark-Based Insulation Panels for Green Building Applications

by Volha Mialeshka and Zoltán Pásztory

Processes 2026, 14(9), 1450; https://doi.org/10.3390/pr14091450 - 30 Apr 2026

Cited by 1 | Viewed by 586

Abstract

Tree bark, an abundant by-product of the timber industry, represents a promising feedstock for sustainable construction. This study investigates the thickness swelling, water absorption, hygroscopicity and mechanical (compressive strength) properties of insulation panels produced from hardwood bark (Tilia spp. and Robinia pseudoacacia [...] Read more.

Tree bark, an abundant by-product of the timber industry, represents a promising feedstock for sustainable construction. This study investigates the thickness swelling, water absorption, hygroscopicity and mechanical (compressive strength) properties of insulation panels produced from hardwood bark (Tilia spp. and Robinia pseudoacacia) via hydromechanical treatment and a wet-forming process. The panels were produced without added adhesives, relying on the formation of hydrogen bonds during the drying phase to ensure structural integrity. Both bark-based insulation boards (thermal conductivity coefficient 0.055–0.057 W/m·K) showed similar hygroscopic behavior, reaching equilibrium moisture contents of max. 25% at 93.9% RH. Water absorption after 24 h immersion was highly material-dependent; Tilia-based panels showed 57.11 ± 5.81%, and Robinia-based panels 320.61 ± 11.34%. Thickness swelling remained low (max. 6% for Robinia), showing significant orthotropic anisotropy. At 10% compressive strain, the Tilia and Robinia bark-based panels showed compressive strengths of 188 ± 14.6 kPa and 298 ± 18.1 kPa, accordingly. These findings demonstrate that hardwood bark can be successfully valorized into high-performance, binderless insulation, supporting circular economic strategies. Full article

(This article belongs to the Special Issue Utilization of Natural and Waste Substances as Eco-Friendly Construction Materials)

► Show Figures

Figure 1

25 pages, 4600 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Graphene Oxide as Valuable Additive for Improving ZnO Electrochemical Properties: Zn/xGO (x = 0, 0.1, and 0.5 wt.%) as Photoelectrocatalysts for Water Splitting and Electrochemical Sensor for Diclofenac

by Ana Nastasić, Katarina Aleksić, Marija Kratovac, Ljiljana Veselinović, Ana Stanković, Marijana Kraljić Roković, Srečo Škapin, Valentin N. Ivanovski, Jelena Belošević-Čavor, Ana Umićević, Ivana Stojković Simatović and Smilja Marković

Processes 2026, 14(9), 1453; https://doi.org/10.3390/pr14091453 - 30 Apr 2026

Viewed by 1294

Abstract

Graphene oxide (GO) was employed as an additive to improve the electrochemical activity of zinc oxide (ZnO) used as both a photoelectrocatalyst for water splitting and an electrochemical sensor for detection of diclofenac. To comprehend the influence of a small amount of GO [...] Read more.

Graphene oxide (GO) was employed as an additive to improve the electrochemical activity of zinc oxide (ZnO) used as both a photoelectrocatalyst for water splitting and an electrochemical sensor for detection of diclofenac. To comprehend the influence of a small amount of GO on the electrochemical activity of ZnO, a series of ZnO/xGO (x = 0, 0.1, and 0.5) particles was synthesized by microwave processing of Zn(OH)₂ precipitate in the presence of 0.1 and 0.5 wt.% of previously prepared GO. The phase composition and crystal structure ordering of ZnO/xGO particles were investigated by XRD and Raman spectroscopy. The optical properties were studied by UV–Vis DRS and PL spectroscopy. The particle morphology was inspected by FE–SEM while the textural properties were analyzed by the low-temperature nitrogen adsorption–desorption method. The (photo)electrocatalytic and electrochemical sensing activities were examined on the ZnO/rxGO modified glassy carbon electrodes (GCEs) prepared by in situ reduction of the ZnO/xGO modified GCEs for 120 s. The electro- and photoelectrocatalytic activity of ZnO/rxGO modified GCEs for water splitting was tested in dark conditions and after 60 min under illumination, respectively, employing linear sweep voltammetry in 0.1 M NaOH and 0.1 M H₂SO₄ as electrolytes. The electrochemical sensing activity of ZnO/rxGO modified GCEs was tested for detection of diclofenac in aqueous solution. The improvement in the electrochemical activity of ZnO was correlated with the added amount of GO, structural defects, and particle morphology. Full article

(This article belongs to the Special Issue Graphene Oxide: From Synthesis to Applications)

► Show Figures

Figure 1

27 pages, 6737 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Enhanced Mechanical Performance and Flame Resistance of Dual-Cured Biobased Unsaturated Polyester Composites Reinforced with Acryloyl-Modified Lignin

by Omar Almoktar Dagale, Aleksandar Marinković, Katarina Simić, Stefan Ivanović, Nataša Knežević, Marija M. Vuksanović, Marina Vukin and Milica Rančić

Processes 2026, 14(9), 1420; https://doi.org/10.3390/pr14091420 - 28 Apr 2026

Cited by 1 | Viewed by 712

Abstract

Materials derived from renewable and recycled resources offer a promising route toward more sustainable thermoset composites. In this study, waste poly(ethylene terephthalate) (PET) was depolymerized by glycolysis with propylene glycol to obtain a glycolysate, and subsequently polycondensed with biobased propylene glycol, maleic anhydride, [...] Read more.

Materials derived from renewable and recycled resources offer a promising route toward more sustainable thermoset composites. In this study, waste poly(ethylene terephthalate) (PET) was depolymerized by glycolysis with propylene glycol to obtain a glycolysate, and subsequently polycondensed with biobased propylene glycol, maleic anhydride, and trimethylolpropane diallyl ether to synthesize biobased UV-curable unsaturated polyester resin (UV-bUPR). The composites were prepared with acryloyl-modified Kraft lignin (K_rL-A) as a reactive bio-filler using a dual-curing approach, in which rapid UV curing was followed by thermal/redox post-curing to improve conversion and network homogeneity. The structure of the synthesized resin and composites was confirmed by FTIR and NMR spectroscopy. Mechanical properties were evaluated by tensile testing and hardness measurements, while morphology and fracture behavior were analyzed by scanning electron microscopy. The unmodified lignin decreased tensile performance due to limited compatibility with the polyester matrix and the formation of interfacial defects and agglomerates. In contrast, K_rL-A exhibited improved dispersion and stronger filler–matrix interactions, resulting in superior mechanical performance. The most pronounced effect of lignin modification was observed at 15 wt.% filler loading, where the tensile strength reached 27.83 MPa, compared with 13.91 MPa for the corresponding unmodified system. The developed composites also showed improved sustainability, assessed through the E-factor, due to the combined use of recycled PET and renewable lignin. Full article

(This article belongs to the Special Issue Advancements in Low-Dimensional Materials: Focus on Detailed Methodologies)

► Show Figures

Figure 1

26 pages, 8797 KB

Open AccessFeature PaperEditor’s ChoiceArticle

CFD Modeling of a Gas–Liquid Reactor for Propylene Hydroformylation

by Lingfeng Mao, Zhongfeng Geng, Baohe Wang, Jing Ma and Jing Zhu

Processes 2026, 14(9), 1414; https://doi.org/10.3390/pr14091414 - 28 Apr 2026

Viewed by 492

Abstract

Propylene hydroformylation is a typical large-scale gas–liquid reaction. Nevertheless, exorbitant costs and theoretical studies lagging far behind practical industry have prevented advancements in reactor efficiency. In this work, the flow, mass transfer, and reaction processes within the gas–liquid reactor were simulated using a [...] Read more.

Propylene hydroformylation is a typical large-scale gas–liquid reaction. Nevertheless, exorbitant costs and theoretical studies lagging far behind practical industry have prevented advancements in reactor efficiency. In this work, the flow, mass transfer, and reaction processes within the gas–liquid reactor were simulated using a three-dimensional CFD-PBM coupled model. The coupling processes between the flow field, mass transfer, and reaction in the gas–liquid reactor are clarified in this study. It provides precise direction for further process optimization by introducing the Hatta number as a quantitative criterion to determine the reaction’s controlling step (mass transfer-controlled or reaction-controlled). The constraints of conventional single-point analysis were overcome by visualizing a Ha number distribution contour, which showed that about 65% of the volume inside the propylene hydroformylation reactor is in a mass transfer-limited state. Based on this, operational parameter optimization was carried out, and the findings show that reaction efficiency may be successfully increased by reasonably raising the superficial gas velocity and system pressure within a certain range. The conversion rate increased by 23% when the superficial gas velocity doubled and by two times when the pressure doubled. Additionally, the effects of the stirring device and rotational speed were investigated, resulting in a 19% increase in conversion rate after optimization. The design and process optimization of similar hydroformylation gas–liquid reactors can benefit from this research. Full article

(This article belongs to the Section Chemical Processes and Systems)

► Show Figures

Graphical abstract

19 pages, 1963 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Influence of Rheological Behavior on Oxygen Transfer and Energetic Efficiency in Pestalotiopsis microspora Cultures

by María Guadalupe Pérez-Loredo, Luis Alberto López-Juárez, Carlos Eduardo Gómez-Sánchez, Claudia Guerero-Barajas, Juan S. Aranda-Barradas and Alberto Ordaz

Processes 2026, 14(9), 1385; https://doi.org/10.3390/pr14091385 - 26 Apr 2026

Cited by 1 | Viewed by 700

Abstract

High-value metabolites, such as antibiotics and enzymes, are primarily produced using filamentous fungi. However, their morphological complexity increases broth viscosity during biomass growth, hindering industrial scale-up by impairing both power input and mass transfer. The interaction between biomass growth, rheology, power input, and [...] Read more.

High-value metabolites, such as antibiotics and enzymes, are primarily produced using filamentous fungi. However, their morphological complexity increases broth viscosity during biomass growth, hindering industrial scale-up by impairing both power input and mass transfer. The interaction between biomass growth, rheology, power input, and oxygen transfer is first addressed here by evaluating mycelial rheology and determining the volumetric mass transfer coefficient (k_La) (dynamic method) and oxygen uptake rate (respirometry) across different operating conditions. These confirmed that the mycelial broth’s pseudoplastic behavior significantly influences volumetric power input and k_La correlations. However, specific power input analysis revealed that operating at higher stirring rates (800 rpm) at higher cell-density cultures is 28.17% more energetically efficient than at low speeds (500 rpm). Furthermore, the oxygen supply-to-demand ratio, calculated via Excel model-fitting, allowed for the estimation of “metabolic power input” which represents the required energy to fit oxygen demand. Results also reveal that at 3.67 ± 0.34 g L⁻¹ of biomass effectively channel up to 51% of total energy toward aerobic metabolism, compared to only 17–30% for 0.73 ± 0.01 g L⁻¹ of biomass. These findings show that volumetric power inputs around 4 kW m⁻³ improve oxygen transfer efficiency, even at relatively high biomass concentrations. Full article

(This article belongs to the Special Issue Novel Concepts for Future Biotechnology and Bioprocesses: Plants and Microorganisms for Sustainable Industries)

► Show Figures

Figure 1

30 pages, 5166 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Influence of Combined Waste-Based Materials on Fine-Grained Concrete Properties

by Giedrius Girskas, Modestas Kligys and Jurgita Malaiškienė

Processes 2026, 14(9), 1364; https://doi.org/10.3390/pr14091364 - 24 Apr 2026

Viewed by 359

Abstract

This study investigates the influence of waste-based materials, namely drinking water treatment sludge (DWTS) and expanded glass production waste (EGPW), on the properties of fine-grained concrete when used as partial Portland cement replacements. Fine-grained concrete mixtures containing different proportions of DWTS and EGPW [...] Read more.

This study investigates the influence of waste-based materials, namely drinking water treatment sludge (DWTS) and expanded glass production waste (EGPW), on the properties of fine-grained concrete when used as partial Portland cement replacements. Fine-grained concrete mixtures containing different proportions of DWTS and EGPW were evaluated in terms of hydration behavior, microstructural development, mechanical performance, durability, and dimensional stability. Density, ultrasonic pulse velocity, water absorption, flexural and compressive strengths, drying shrinkage, and porosity parameters were determined, while frost resistance was assessed and predicted based on porosity characteristics. Hydration kinetics were analyzed using X-ray diffraction and semi-adiabatic calorimetry. The results showed that increasing EGPW content enhanced cement hydration processes and promoted matrix densification through pozzolanic reactions, resulting in reduced water absorption and improved mechanical properties. In contrast, DWTS exhibited an inhibiting effect on hydration due to its inert nature and high Fe₂O₃ content, acting primarily as a micro-filler; however, when combined with EGPW at moderate dosages, DWTS contributed positively to flexural strength and slightly reduced drying shrinkage. The combined use of DWTS and EGPW enabled the formation of a balanced pore structure and improved the durability of fine-grained concrete. Among the tested mixtures, ED-3 (7.5% EGPW + 5% DWTS) provided the most favorable balance between hydration activation and binder reduction, while the highest frost resistance was achieved by the ED-4 mixture, reaching approximately 603 predicted freeze–thaw cycles. Overall, the results indicate that properly optimized combinations of EGPW and DWTS can significantly enhance the performance and durability of fine-grained concrete while controlling drying shrinkage. Full article

(This article belongs to the Special Issue Recycling and Value-Added Utilization of Secondary Resources)

► Show Figures

Figure 1

18 pages, 6148 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Mass-Integrated PVC Production with Direct Recycling: An Environmental Evaluation Based on WAR Method

by Linda Mychell Puello-Castellón, Rolando Manuel Guardo-Ruiz and Ángel Darío González-Delgado

Processes 2026, 14(9), 1350; https://doi.org/10.3390/pr14091350 - 23 Apr 2026

Viewed by 477

Abstract

Over the past decades, global plastic demand has steadily increased due to the favorable physicochemical properties of these materials, including low weight, durability, versatility, and low production cost. Among synthetic polymers, polyvinyl chloride (PVC) is one of the most widely produced, accounting for [...] Read more.

Over the past decades, global plastic demand has steadily increased due to the favorable physicochemical properties of these materials, including low weight, durability, versatility, and low production cost. Among synthetic polymers, polyvinyl chloride (PVC) is one of the most widely produced, accounting for approximately 10% of global polymer production. Suspension polymerization is commonly used for its manufacture because of its high productivity and suitable operational control; however, this process is associated with considerable energy consumption and emissions with potential environmental impacts. In this work, the Waste Reduction (WAR) Algorithm was applied to evaluate the environmental performance of a PVC production process with mass integration and direct water recycling. The Potential Environmental Impact (PEI) was quantified under four scenarios, considering both generation and output rates, as well as different fuel sources. The results showed that the environmental performance of the system strongly depends on the selected system boundaries and on the incorporation of energy-related effects. Under the gate-to-gate scope considered, some scenarios exhibited negative net PEI generation values, indicating that the PEI associated with the outlet streams was lower than that of the inlet streams within the modeled system. However, when energy consumption was included, it became the main contributor to total PEI, reaching 2560 and 3070 PEI/day in Cases 3 and 4, respectively. The toxicological assessment showed that ATP was the only category with positive PEI generation, while natural gas presented the lowest potential environmental impact among the energy sources evaluated. Overall, the process showed comparatively favorable environmental performance within the assumptions and methodological boundaries of the WAR analysis. Full article

(This article belongs to the Section Environmental and Green Processes)

► Show Figures

Figure 1

23 pages, 2472 KB

Open AccessEditor’s ChoiceReview

Biomass Pyrolysis: Recent Advances in Characterisation and Energy Utilisation

by Hamid Reza Nasriani and Maryam Nasiri Ghiri

Processes 2026, 14(8), 1321; https://doi.org/10.3390/pr14081321 - 21 Apr 2026

Cited by 3 | Viewed by 1274

Abstract

Biomass pyrolysis has emerged as a flexible platform for converting low-value residues into higher-value energy carriers (bio-oil, biochar and gas) and carbon-rich materials, with realistic potential for negative emissions when biochar is deployed in long-lived sinks. Over the last decade, three developments have [...] Read more.

Biomass pyrolysis has emerged as a flexible platform for converting low-value residues into higher-value energy carriers (bio-oil, biochar and gas) and carbon-rich materials, with realistic potential for negative emissions when biochar is deployed in long-lived sinks. Over the last decade, three developments have driven the field forward: first, a finer mechanistic understanding of devolatilization and secondary reactions; second, major improvements in analytical techniques for characterising feedstocks and products; and third, more rigorous techno-economic and life-cycle assessments that place pyrolysis in a broader energy-system context. Recent experimental work on forestry and agro-industrial residues has clarified how biomass composition, ash chemistry and operating conditions jointly govern product yields, energy content and stability. Parallel advances in GC×GC–MS, high-resolution mass spectrometry, NMR and thermogravimetric methods have shifted the discussion from bulk “bio-oil” and “char” to families of molecules and well-defined structural domains, which can be deliberately targeted by reactor and catalyst design. Data-driven models, ranging from support vector machines applied to TGA curves to ANFIS and random forests for yield prediction, are now accurate enough to support process screening and multi-objective optimisation. At the system level, commercial fast pyrolysis biorefineries report overall useful energy efficiencies on the order of 80–86%, while slow pyrolysis configurations centred on biochar can be economically viable when carbon storage and co-products are appropriately valued. Thermodynamic analyses confirm that indirect gasification via fast-pyrolysis oil sacrifices some energy and exergy efficiency relative to direct solid-biomass gasification but may offer logistical and integration advantages. This review synthesises recent work on (i) feedstock and process characterisation; (ii) state-of-the-art analytical methods for bio-oil, biochar and gas; (iii) modelling and machine-learning tools; and (iv) energy-system deployment of pyrolysis products. Throughout, the emphasis is on how characterisation and modelling inform concrete design choices and on the trade-offs that arise when pyrolysis is considered as part of a wider decarbonisation portfolio. By integrating laboratory-scale characterisation with system-level modelling, this review aligns biomass pyrolysis with several United Nations Sustainable Development Goals (SDGs). The optimisation of thermochemical conversion pathways for forestry and agro-industrial residues directly supports SDG 7 (Affordable and Clean Energy) by enhancing the efficiency of bio-oil and syngas production. Furthermore, the deployment of biochar as a stable carbon sink for negative emissions and soil amendment addresses SDG 13 (Climate Action) and SDG 15 (Life on Land). By converting low-value waste streams into high-value energy carriers and chemicals within a circular bioeconomy framework, the research further contributes to SDG 12 (Responsible Consumption and Production) and SDG 9 (Industry, Innovation and Infrastructure). Full article

(This article belongs to the Special Issue Biomass Pyrolysis Characterization and Energy Utilization)

► Show Figures

Figure 1

17 pages, 2683 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Development of an Original Method for Analyzing Hydrotreated Vegetable Oil Composition by Gas Chromatography

by Maria Oprea, Rodica Niculescu, Mihaela Nastase, Adrian Clenci, Gabriel Vasilievici, Andreea Luiza Mirt and Ana Maria Apolozan

Processes 2026, 14(8), 1300; https://doi.org/10.3390/pr14081300 - 18 Apr 2026

Viewed by 812

Abstract

The development of modern society has intensified fossil fuel consumption, resulting in the depletion of oil resources and rising greenhouse gas emissions. In this context, the promotion of renewable alternatives in the transport sector has become essential, with Hydrotreated Vegetable Oil (HVO) emerging [...] Read more.

The development of modern society has intensified fossil fuel consumption, resulting in the depletion of oil resources and rising greenhouse gas emissions. In this context, the promotion of renewable alternatives in the transport sector has become essential, with Hydrotreated Vegetable Oil (HVO) emerging as a promising transitional fuel due to its compatibility with conventional diesel engines. To ensure proper engine operation and performance, the physical properties and chemical structure of HVO must be accurately characterized. Gas chromatography is commonly used for this purpose. While dedicated gas chromatography methods for HVO are available on specialized equipment, this study proposes a chromatographic method applicable to conventional gas chromatograph systems equipped with a flame ionization detector, enabling the analysis of HVO using commonly available laboratory equipment. The method was developed using commercially available HVO and pure n-alkanes (C₅–C₁₈) as reference compounds for component identification. The proposed approach enabled the estimation of carbon and hydrogen atom numbers in the analyzed fuel fractions and the determination of the stoichiometric air. The calculated values show good agreement with the literature data, confirming the reliability and applicability of the proposed boiling-point-based chromatographic method. Full article

(This article belongs to the Special Issue Advanced Natural Product Technology: Extraction, Separation, and Analysis)

► Show Figures

Figure 1

17 pages, 2306 KB

Open AccessEditor’s ChoiceArticle

Comparison of Aspen Plus and Machine Learning for Syngas Composition Prediction in Biomass Gasification

by Nuno M. O. Dias and Fernando G. Martins

Processes 2026, 14(8), 1298; https://doi.org/10.3390/pr14081298 - 18 Apr 2026

Viewed by 1224

Abstract

Accurate prediction of syngas composition is essential for process design, optimization, and scale-up, yet it remains challenging due to interactions among operating conditions, biomass properties, and chemical reactions. This study used a database of 450 experimental observations spanning a wide range of biomass [...] Read more.

Accurate prediction of syngas composition is essential for process design, optimization, and scale-up, yet it remains challenging due to interactions among operating conditions, biomass properties, and chemical reactions. This study used a database of 450 experimental observations spanning a wide range of biomass feedstocks and operating conditions to compare the predictive performance of Aspen Plus simulations and Machine Learning models in estimating the concentrations of CO, CO₂, H₂, and CH₄ in syngas. Aspen Plus was used to simulate the 4 stages of the biomass gasification process under different operating conditions, with special focus on the three reactor modules (RPlug, RGibbs, and REquil) modeling the last two stages. In parallel, Machine Learning models using four regression algorithms (XGBoost, Support Vector Machines, Random Forest and Artificial Neural Networks), with different preprocessing and data-splitting strategies, were evaluated for predicting syngas composition. The best Machine Learning models achieved R² values of 0.753 (CO), 0.866 (CO₂), 0.879 (H₂) and 0.734 (CH₄) on the test set. These results outperformed the Aspen Plus approach and highlight the potential of Machine Learning models as complementary or alternative tools for modelling biomass gasification. Shapley Additive Explanation analysis identified the most influential input variables, revealing key roles for the steam-to-biomass ratio and the equivalence ratio in predicting syngas composition. This study demonstrates that existing Aspen Plus simulation models require further development to improve performance metrics across a wide range of biomass feedstocks and operating conditions. Full article

(This article belongs to the Section Chemical Processes and Systems)

► Show Figures

Figure 1

33 pages, 2074 KB

Open AccessEditor’s ChoiceReview

Catalytic Technologies for Arsenic Remediation: A Comprehensive Review of Advanced Oxidation Processes, Bifunctional Materials, and Field Applications

by Vanina Soledad Aghemo, Fernanda Miranda Zoppas, Jose Sureda, Tatiane Benvenuti, Andrea Moura Bernardes and Fernanda Albana Marchesini

Processes 2026, 14(8), 1293; https://doi.org/10.3390/pr14081293 - 17 Apr 2026

Viewed by 895

Abstract

Arsenic contamination in groundwater is a severe and widespread environmental and public health challenge. Recent years have witnessed rapid advances in catalytic remediation technologies, particularly those integrating advanced oxidation processes (AOPs), bifunctional materials, and field-scale applications. This comprehensive review synthesizes recent developments, emphasizing [...] Read more.

Arsenic contamination in groundwater is a severe and widespread environmental and public health challenge. Recent years have witnessed rapid advances in catalytic remediation technologies, particularly those integrating advanced oxidation processes (AOPs), bifunctional materials, and field-scale applications. This comprehensive review synthesizes recent developments, emphasizing the synergy between catalytic oxidation and adsorption, the design of innovative and recyclable materials, and the practical translation of laboratory findings to real-world remediation scenarios. Key breakthroughs include dual-function catalysts for combined contaminant removal, scalable systems compatible with renewable energy, and hybrid strategies integrating conventional and catalytic routes. Case studies from arsenic hotspots worldwide demonstrate not only technological feasibility but also highlight knowledge gaps and sustainability challenges. By evaluating catalytic mechanisms, operational performance, and environmental impact, this review identifies promising directions for the next generation of arsenic remediation and offers a critical roadmap to guide future research and practice. Full article

(This article belongs to the Special Issue Advanced Photocatalytic and Electrochemical Processes for Water and Wastewater Treatment)

► Show Figures

Graphical abstract

18 pages, 4643 KB

Open AccessEditor’s ChoiceArticle

Sustainable Polysulfone Composite Membranes Incorporating Medium-Density Fiberboard Residue for Dairy Effluent Remediation

by Bruna Naiara Silva de Oliveira Almeida, Rafael Agra Dias, Pamela Thainara Vieira da Silva, Renê Anisio da Paz, Bruna Aline Araujo, Carlos Bruno Barreto Luna, Renate Maria Ramos Wellen and Edcleide Maria Araújo

Processes 2026, 14(8), 1265; https://doi.org/10.3390/pr14081265 - 15 Apr 2026

Cited by 1 | Viewed by 588

Abstract

The global shift toward sustainable industrial processes has increased the demand for advanced materials capable of performing under harsh conditions, with high-temperature polymer nanocomposites emerging as a key development area. This study investigates the fabrication of sustainable polysulfone (PSU)/medium-density fiberboard (MDF) nanocomposites through [...] Read more.

The global shift toward sustainable industrial processes has increased the demand for advanced materials capable of performing under harsh conditions, with high-temperature polymer nanocomposites emerging as a key development area. This study investigates the fabrication of sustainable polysulfone (PSU)/medium-density fiberboard (MDF) nanocomposites through phase inversion, using PSU—a matrix known for its high glass transition temperature—as the base. Membranes were created by adding MDF residue at 1, 3, 5, 7, and 10 phr (parts per hundred resin). Characterization included analyzing polymer solution viscosity, ATR-FTIR, contact angle, SEM, porosity, equilibrium water content, average pore radius, tensile testing, and permeation performance. Incorporating MDF residue increased solution viscosity and affected porosity and the structure of the top layer. Mechanical testing showed MDF acted as a functional additive, improving the elastic modulus and tensile strength, and supporting overall structural stability under hydraulic stress. The membranes exhibited competitive water flux and maintained high selectivity (80–92% rejection; over 95% turbidity removal) at 1.0 and 2.0 bar. The 3 and 5 phr levels optimized performance, demonstrating that repurposing industrial waste within high-performance matrices is a practical approach for producing durable materials that meet the needs of energy systems and complex industrial separation processes. Full article

(This article belongs to the Special Issue Sustainable Materials for Energy Industry: High-Temperature Polymer Nanocomposites)

► Show Figures

Figure 1

21 pages, 3597 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Interfacial Organization in CuO-Based Nanobiocatalysts for Cellulose Saccharification: Influence of Enzyme Loading on Catalytic Behavior

by Naiara Jacinta Clerici, Ryan dos Santos Silva, Daniel Tibério Ferreira, Fabio Patrício Sanchez Vera, Maria Ismenia Sodero Toledo Faria, Júlio César dos Santos and Sílvio Silvério da Silva

Processes 2026, 14(8), 1254; https://doi.org/10.3390/pr14081254 - 15 Apr 2026

Viewed by 1219

Abstract

The enzymatic saccharification of cellulose remains a key step in biomass conversion processes, often influenced by enzyme stability, distribution, and accessibility at solid–liquid interfaces. Immobilization of cellulolytic enzymes on nanostructured supports has been proposed as a strategy to modulate catalytic behavior; however, the [...] Read more.

The enzymatic saccharification of cellulose remains a key step in biomass conversion processes, often influenced by enzyme stability, distribution, and accessibility at solid–liquid interfaces. Immobilization of cellulolytic enzymes on nanostructured supports has been proposed as a strategy to modulate catalytic behavior; however, the relationship between enzyme loading and catalytic response remains insufficiently understood. In this study, CuO-based nanobiocatalysts were prepared through controlled cellulase immobilization and systematically evaluated under defined experimental conditions. Structural and physicochemical characterization was performed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and integrated thermal analysis (TGA–DTG–DSC), enabling a comparative assessment of the analyzed systems. SEM analysis showed that the average particle diameter increased from 39.5 ± 14.8 nm (CuO nanoparticles) to 95.6 ± 21.8 nm (NPI10), 106.6 ± 27.7 nm (NPI15), and 113.5 ± 23.1 nm (NPI20), indicating progressive variations in particle organization with increasing enzyme loading. Catalytic performance was evaluated through enzymatic hydrolysis of cellulose filter paper as a model substrate, with products quantified by HPLC at a representative reaction time. The system prepared at lower enzyme loading (NPI10) exhibited product formation comparable to that of the free enzyme, with apparent average glucose formation values of 1.054 and 1.047 mg·mL⁻¹·h⁻¹, respectively. In contrast, higher immobilization levels were associated with reduced catalytic output. Across all systems, glucose was the predominant product, with negligible accumulation of intermediate oligomers under the evaluated conditions. These results indicate that increasing enzyme loading does not correspond to proportional increases in product formation and highlight the influence of enzyme distribution and accessibility within the system. The combined structural and catalytic observations provide a controlled framework for evaluating how immobilization conditions influence system behavior in nanobiocatalytic systems. Full article

(This article belongs to the Special Issue Advanced Biofuel Production Processes and Technologies)

► Show Figures

Graphical abstract

24 pages, 2758 KB

Open AccessEditor’s ChoiceReview

Optimization in Chemical Engineering: A Systematic Review of Its Evolution, State of the Art, and Emerging Trends

by Carlos Antonio Padilla-Esquivel, Gema Báez-Barrón, Carlos Daniel Gil-Cisneros, Diana Karen Zavala-Vega, Eduardo García-García, Vanessa Villazón-León, Heriberto Alcocer-García, Fabricio Nápoles-Rivera, César Ramírez-Márquez and José María Ponce-Ortega

Processes 2026, 14(8), 1247; https://doi.org/10.3390/pr14081247 - 14 Apr 2026

Viewed by 2597

Abstract

Optimization has played a fundamental role in the evolution of chemical engineering, enabling systematic decision-making under technical, economic, and environmental constraints. This review presents a structured and comparative analysis of the historical development and current state of optimization methodologies applied to chemical engineering, [...] Read more.

Optimization has played a fundamental role in the evolution of chemical engineering, enabling systematic decision-making under technical, economic, and environmental constraints. This review presents a structured and comparative analysis of the historical development and current state of optimization methodologies applied to chemical engineering, covering the transition from early linear and nonlinear programming approaches to advanced data-driven and artificial intelligence-based frameworks. A systematic literature review was conducted following the PRISMA guidelines, through which a total of 101 articles were retained for analysis. The results indicate that mixed-integer programming and decomposition-based methods remain widely adopted for structured industrial problems, while metaheuristic and hybrid data-driven approaches have experienced significant growth in recent years. In particular, a clear trend toward the integration of machine learning and surrogate modeling techniques is observed, driven by the need to address large-scale, non-convex, and highly nonlinear systems. The analysis reveals a clear methodological shift from classical linear optimization frameworks toward hybrid optimization strategies capable of addressing large-scale, non-convex, and highly nonlinear problems. Finally, current challenges and future research directions are identified, emphasizing the need for robust hybrid approaches that combine mathematical programming and intelligent algorithms to effectively manage complexity in next-generation chemical systems. Full article

(This article belongs to the Special Issue Low/Zero Carbon Fuels Production, Transportation, Storage and Utilization)

► Show Figures

Figure 1

19 pages, 3751 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Efficient Geothermal Reservoir Simulation Using Deep Learning Surrogates and Multiscale Interpolation Techniques

by Vaibhav V. Khedekar, Abdul R. A. N. Memon and Mayur Pal

Processes 2026, 14(8), 1248; https://doi.org/10.3390/pr14081248 - 14 Apr 2026

Cited by 1 | Viewed by 1333

Abstract

Accurate prediction of subsurface temperature distributions is essential for geothermal reservoir assessment, thermal performance evaluation, and decision support in reservoir management. However, repeated high-resolution numerical simulations are computationally expensive, particularly when multiple scenarios, heterogeneous petrophysical fields, and varying grid resolutions must be analyzed. [...] Read more.

Accurate prediction of subsurface temperature distributions is essential for geothermal reservoir assessment, thermal performance evaluation, and decision support in reservoir management. However, repeated high-resolution numerical simulations are computationally expensive, particularly when multiple scenarios, heterogeneous petrophysical fields, and varying grid resolutions must be analyzed. This study presents a U-Net-based surrogate modeling framework for fast geothermal temperature field prediction on structured grids, coupled with interpolation strategies for handling unseen grid resolutions and intermediate time instances. Training and evaluation data are generated using the MATLAB Reservoir Simulation Toolbox (MRST) (24.1.0.2578822 (R2024a) Update 2) under multiple porosity–permeability realizations and at several grid resolutions (130 × 73, 67 × 37, 36 × 19, and 20 × 11) on a 2D grid. Data preprocessing and reshaping techniques are used to preserve spatial correspondence across resolutions. For fixed trained grids, the surrogate directly predicts temperature fields from porosity, permeability, and time inputs. For unseen grids, a grid interpolation strategy combines predictions from neighboring trained resolutions using weighted blending based on target grid cell count, followed by spatial resizing to the requested resolution. In addition, time interpolation is used to estimate temperature maps at intermediate time steps between predicted/simulated snapshots. The proposed framework enables rapid generation of temperature maps while maintaining spatial structure, making it suitable for efficient geothermal screening and multiscale scenario analysis. Full article

(This article belongs to the Special Issue Advanced Reservoir Simulation and Modelling, Thermal and Enhanced Oil Recovery Processes (2nd Edition))

► Show Figures

Figure 1

28 pages, 8747 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Physics-Informed Fusion Neural Network for Real-Time Bottomhole Pressure Control in Managed Pressure Drilling

by Liwei Wu, Ziyue Zhang, Chengkai Zhang, Gensheng Li, Xianzhi Song, Mengmeng Zhou and Xuezhe Yao

Processes 2026, 14(8), 1240; https://doi.org/10.3390/pr14081240 - 13 Apr 2026

Cited by 1 | Viewed by 1032

Abstract

Managed pressure drilling (MPD) is the core technology for developing formations with high pressure and narrow density windows. It precisely maintains the bottomhole pressure (BHP) within the safe operating window defined by formation pore pressure and fracture pressure by actively regulating the wellbore [...] Read more.

Managed pressure drilling (MPD) is the core technology for developing formations with high pressure and narrow density windows. It precisely maintains the bottomhole pressure (BHP) within the safe operating window defined by formation pore pressure and fracture pressure by actively regulating the wellbore pressure profile. If pressure control becomes unstable, it can easily trigger gas kicks or lost circulation, posing a severe threat to operational safety. However, existing model predictive control (MPC) schemes have significant limitations: pure data-driven models exhibit poor generalization under complex conditions, while control algorithms based on traditional mechanistic models struggle to meet the stringent real-time requirements of field control cycles due to high-complexity numerical iteration processes. To balance control precision and real-time performance, this paper proposes a physics-informed model predictive control framework (PINC-MPC). During the training phase, physical prior knowledge such as the law of mass conservation is embedded into the neural network as constraints to construct a physically consistent deep surrogate model, enabling it to characterize complex wellbore characteristics. In the control phase, this surrogate model replaces the time-consuming numerical solving process of the mechanistic model within the MPC loop, achieving near-real-time state prediction and rolling optimization while ensuring physical fidelity. Experimental results indicate that PINC-MPC demonstrates superior control performance. Its median single-step solving time is only 16.81 ms, achieving an 11.1-fold acceleration compared to the mechanistic model-based scheme (187.3 ms). In a 5000 s full-cycle closed-loop control experiment, the total time required for the former is only 1.68 s, while the latter reaches 18.73 s, representing an efficiency improvement of approximately 91%. In terms of control accuracy, the integrated absolute error (IAE), reflecting the total deviation of the control process, significantly decreased from 63.40 MPa·s for the industrial successive linearization MPC (SLMPC) to 12.90 MPa·s, an improvement of 79.7%. Especially in extreme dynamic conditions such as simulated pump shutdowns for pipe connections and sudden gas kicks, the framework demonstrates excellent predictive ability and response efficiency. It can proactively trigger compensation actions to keep BHP fluctuations within 0.30 MPa, significantly outperforming the traditional SLMPC method. The research results prove that PINC-MPC provides an efficient, precise, and robust nonlinear control strategy for MPD systems, offering important engineering reference value for enhancing the automation level of intelligent drilling systems. Full article

(This article belongs to the Special Issue Applications of Intelligent Models in the Petroleum Industry)

► Show Figures

Figure 1

43 pages, 2838 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Advances in Optimal Reactive Power Dispatch: Formulations, Solution Approaches, and Future Directions

by Edgar E. Tibaduiza-Rincón, Walter M. Villa-Acevedo and Jesús M. López-Lezama

Processes 2026, 14(8), 1229; https://doi.org/10.3390/pr14081229 - 11 Apr 2026

Viewed by 826

Abstract

This paper provides a comprehensive analysis of the Optimal Reactive Power Dispatch (ORPD) problem, focusing on its mathematical formulations and the methodologies employed to solve it. This paper systematically categorizes the problem into single-objective and multi-objective formulations, as well as single-period and multi-period [...] Read more.

This paper provides a comprehensive analysis of the Optimal Reactive Power Dispatch (ORPD) problem, focusing on its mathematical formulations and the methodologies employed to solve it. This paper systematically categorizes the problem into single-objective and multi-objective formulations, as well as single-period and multi-period models, and addresses both single-area and multi-area operational frameworks. It explores a broad range of optimization techniques used to tackle the ORPD problem, including classical optimization methods, metaheuristic algorithms, and hybrid approaches. Additionally, this paper discusses the incorporation of uncertainty in ORPD models, highlighting methods to account for the stochastic nature of power systems. A critical assessment of the current literature identifies existing knowledge gaps and outlines promising future research directions. This paper aims to provide researchers with a thorough understanding of the ORPD problem, offering insights into emerging trends and areas for further exploration. Full article

(This article belongs to the Special Issue Optimization and Analysis of Energy System)

► Show Figures

Figure 1

20 pages, 1534 KB

Open AccessEditor’s ChoiceArticle

Modelling Oxygen Transport, Microcarrier Aggregation, and Hydrodynamic Constraints in Stirred Bioreactors for Scalable Developmental Engineering

by Ben Logan and Tao Sun

Processes 2026, 14(8), 1219; https://doi.org/10.3390/pr14081219 - 10 Apr 2026

Viewed by 610

Abstract

Developmental engineering (DE) is a bottom-up strategy for generating functional tissues from modular tissues (MTs), offering potential advantages over conventional top-down approaches. However, scalable MT production remains constrained by limited understanding of scaffold aggregation, oxygen transport, and hydrodynamic effects in bioreactors. This study [...] Read more.

Developmental engineering (DE) is a bottom-up strategy for generating functional tissues from modular tissues (MTs), offering potential advantages over conventional top-down approaches. However, scalable MT production remains constrained by limited understanding of scaffold aggregation, oxygen transport, and hydrodynamic effects in bioreactors. This study integrates theoretical simulations with empirical correlations to analyze these factors and provide a systematic basis for MT production. Microcarrier aggregates were modelled to evaluate minimum oxygen concentration (C_min). Results indicate that larger microcarrier diameters (d_mc) are associated with increased C_min due to longer diffusion distances. Aggregate geometry and packing configuration, including hexagonal close packing and the “kissing number,” influenced oxygen distribution and may explain observed C_min plateaus. Hydrodynamic behaviour was assessed using the Zwietering correlation and Kolmogorov turbulence scaling. Denser microcarrier aggregates required higher minimum stirring speeds (N_min), while larger d_mc increased susceptibility to shear. Increased agitation intensity and more aggressive impeller designs reduced N_min but were associated with potential cell damages. Higher medium density (e.g., 20% FBS) reduced shear stress and energy dissipation. A unified framework integrating oxygen diffusion, aggregate geometry, microcarrier properties, and hydrodynamics is proposed to estimate oxygen limitation and cell damage, highlighting trade-offs relevant to MT production in DE. Full article

(This article belongs to the Section Biological Processes and Systems)

► Show Figures

Figure 1

13 pages, 2341 KB

Open AccessEditor’s ChoiceArticle

Sustainable Gypsum Composites with the Addition of Bio-Waste: Thermal, Mechanical, and Physical Properties

by Andżelika Krupińska, Zuzanna Kamińska, Sylwia Włodarczak, Magdalena Matuszak and Marek Ochowiak

Processes 2026, 14(8), 1220; https://doi.org/10.3390/pr14081220 - 10 Apr 2026

Viewed by 601

Abstract

This study presents the results of research on the modification of gypsum with bio-waste to improve its thermal insulation properties and to evaluate the influence of the type and amount of the additive on the physical, mechanical, and microstructural properties of the composite. [...] Read more.

This study presents the results of research on the modification of gypsum with bio-waste to improve its thermal insulation properties and to evaluate the influence of the type and amount of the additive on the physical, mechanical, and microstructural properties of the composite. Various fractions of plant-based bio-waste were used in amounts ranging from 0.75 to 10% by weight. The thermal conductivity coefficient and thermal diffusivity were determined. Additionally, analyses of dimensional stability over time, visual appearance, and phase distribution uniformity were conducted. Mechanical tests included surface hardness measurements. In order to determine the material’s durability, water absorption and frost resistance tests were performed, and structural changes and properties after these cycles were analyzed. It was found that selecting the appropriate type and proportion of additive makes it possible to obtain composites with a favorable balance between thermal insulation, dimensional stability, and mechanical performance. The conducted research confirms the potential for effective use of bio-waste as a gypsum-modifying raw material, contributing to the development of sustainable building materials with a reduced environmental footprint and improved functional parameters. Full article

(This article belongs to the Special Issue Synthesis, Application and Structural Analysis of Composite Materials)

► Show Figures

Figure 1

20 pages, 4507 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Modification Effects of High-Pressure Homogenization and Decolorization on Microalgae-Fortified 3D-Printed Foods

by Dalne Sinclair, Armin Mirzapour-Kouhdasht, Juan A. Velasquez, Da Chen, Senay Simsek and Jen-Yi Huang

Processes 2026, 14(8), 1221; https://doi.org/10.3390/pr14081221 - 10 Apr 2026

Viewed by 808

Abstract

The global transition towards sustainable food systems has intensified the search for alternative protein sources that can meet human nutritional demands with reduced environmental impacts. Although microalgae are rich in protein, their applications in food remain limited due to thick cell walls and [...] Read more.

The global transition towards sustainable food systems has intensified the search for alternative protein sources that can meet human nutritional demands with reduced environmental impacts. Although microalgae are rich in protein, their applications in food remain limited due to thick cell walls and intense green color. The aim of this study is to modify Chlorella vulgaris by high-pressure homogenization (HPH) and decolorization to improve its processability for extrusion-based 3D printing. Microalgal biomass was pretreated by HPH at different pressures (10,000, 15,000, 20,000 psi) for one to three passes, followed by pigment removal using ethanol of different concentrations (70, 85, 100%). Microscopic imaging shows that HPH effectively disrupted microalgal cell walls and caused cell disintegration, resulting in increased foaming stability (22–28%) but lower solubility (up to 24%), with other functional properties largely preserved. Ethanol treatments markedly decolored microalgae and increased their water-holding capacity (10–45%) and solubility (6–11%). The formulation of HPH-treated decolorized microalgae with soy protein isolate and xanthan gum increased the viscosity (66–179%) and elasticity (78–235%) of printing inks. The resulting 3D prints show higher hardness (47–128%), springiness (up to 155%) and chewiness (47–408%). The information obtained from this study provides guidance for modifying the functional and rheological properties of microalgae and contributes to advancing the formulation and manufacturing of microalgae-based foods. Full article

(This article belongs to the Special Issue Innovative Bioreactor Design and Advanced Optimization Strategies for Biorefineries and Bioprocessing)

► Show Figures

Figure 1

25 pages, 794 KB

Open AccessEditor’s ChoiceArticle

Integrated Assessment of Solid, Liquid, and Gaseous Fuels Derived from Fixed-Bed Pyrolysis of Waste Tires

by Harryson Guimarães de Lima, Clériston Moura Vieira Júnior, Humberto Santos, Adalberto Freire do Nascimento Júnior, Antônio Celso Dantas Antonino and Sérgio Peres Ramos da Silva

Processes 2026, 14(8), 1197; https://doi.org/10.3390/pr14081197 - 9 Apr 2026

Viewed by 743

Abstract

The improper disposal of end-of-life tires poses significant environmental challenges due to their petroleum-based composition and slow degradation, while simultaneously representing an underutilized energy resource. This study investigates the slow pyrolysis of shredded waste tires in a fixed-bed electrically heated reactor to evaluate [...] Read more.

The improper disposal of end-of-life tires poses significant environmental challenges due to their petroleum-based composition and slow degradation, while simultaneously representing an underutilized energy resource. This study investigates the slow pyrolysis of shredded waste tires in a fixed-bed electrically heated reactor to evaluate the production and fuel properties of gaseous, liquid, and solid fractions. Experiments were conducted with 100 g samples under nitrogen at final temperatures of 400, 500, and 600 °C, with residence times of 40, 25, and 10 min, respectively. Higher temperatures promoted gas formation, increasing yields from 27% to 32% and achieving a maximum lower heating value of 30.54 MJ m⁻³ at 600 °C, with enhanced H₂ and CH₄ contents. Solid yields decreased slightly (41% to 37%), while char maintained stable heating values (~29 MJ kg⁻¹). Liquid yields remained near 33% and showed high calorific values (~41 MJ kg⁻¹), densities of 700–770 kg m⁻³, low acidity, low ash content, and increased viscosity at higher temperatures. Energy conversion efficiency reached 74.4% at 500 °C. The integrated evaluation of all fractions under identical conditions highlights fixed-bed pyrolysis as a promising pathway for waste-tire valorization and decentralized fuel production. Full article

(This article belongs to the Special Issue Green Metallurgical Process and Technology)

► Show Figures

Figure 1

20 pages, 583 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Beyond the Essential Oil: Circular Economy Strategies for Lavender Solid Residues

by Milica Aćimović, Djorđe Djatkov, Aleksandar Nesterović, Stanko Milić, Nikolina Dizdar, Nebojša Kladar, Zorica Tomičić, Slađana Rakita and Ivana Čabarkapa

Processes 2026, 14(8), 1191; https://doi.org/10.3390/pr14081191 - 8 Apr 2026

Viewed by 1107

Abstract

The aim of this study was to comprehensively characterize lavender pellets produced from post-distillation residues and evaluate their multifunctional valorization potential. Physicochemical properties, including moisture, ash, heating value, organic matter, total and organic carbon, macro- and micronutrients, potentially toxic heavy metals, polyphenols, microbiological [...] Read more.

The aim of this study was to comprehensively characterize lavender pellets produced from post-distillation residues and evaluate their multifunctional valorization potential. Physicochemical properties, including moisture, ash, heating value, organic matter, total and organic carbon, macro- and micronutrients, potentially toxic heavy metals, polyphenols, microbiological safety, and nutritive composition, were assessed. The pellets demonstrated an energy content comparable to other agricultural residues, with a higher heating value of 18,900 kJ/kg and a lower heating value of 16,603 kJ/kg. High organic matter (87%) and a slightly acidic pH support soil moisture retention, while favorable macronutrient levels enhance their suitability as a soil amendment. Water-based extractions (infusion and decoction) achieved higher yields (15.60–21.66%) than ethanol (13.04%) and more effectively recovered bioactive polyphenols, particularly rosmarinic and chlorogenic acids. Low moisture and water activity ensured storage stability and minimal microbial growth, which was confirmed by microbiological safety tests. Nutritionally, pellets contained moderate protein (9.38%), high cellulose (33.38%), and low fat (2.18%), with total amino acids of 8.91 g/100 g and 36.7% essential amino acids, along with a favorable fatty acid profile rich in polyunsaturated fractions. Overall, these findings highlight lavender pellets as a sustainable resource for energy, soil improvement, bioactive compound recovery, and complementary animal feed within circular economy frameworks. However, future research should focus on investigating whether residual compounds remain in lavender residues that could exert antifeedant or phytotoxic effects. Additionally, the potential for the sequential valorization of lavender residues should be explored, initially through the extraction of bioactive phenols, followed by pellet production for use as fuel or soil amendments. This approach would enable multiple cascading uses and maximize their contribution to comprehensive circular economy strategies. Full article

(This article belongs to the Special Issue Analysis and Processes of Bioactive Components in Natural Products)

► Show Figures

Figure 1

24 pages, 762 KB

Open AccessEditor’s ChoiceReview

Assessing the Feasibility of Repurposing the Existing Natural Gas Pipelines for Hydrogen Transport—A Comprehensive Review

by Oluwole Foluso Ayodele and Dallia Ali

Processes 2026, 14(7), 1182; https://doi.org/10.3390/pr14071182 - 7 Apr 2026

Cited by 1 | Viewed by 1623

Abstract

In a bid to investigate the optimum transportation method for offshore wind-produced hydrogen (H₂) and assess the feasibility of repurposing the existing oil and gas infrastructure for H₂ transmission, this paper assesses the existing H₂ transportation methods with a [...] Read more.

In a bid to investigate the optimum transportation method for offshore wind-produced hydrogen (H₂) and assess the feasibility of repurposing the existing oil and gas infrastructure for H₂ transmission, this paper assesses the existing H₂ transportation methods with a comprehensive review of the H₂ impact on the existing natural gas pipeline infrastructure. To establish the possibility of repurposing the existing natural gas (NG) pipelines for H₂ gas transport, this paper reviews the influential technical measures—composition, pressure, temperature, volumetric energy density, density, and pressure drop—to assess whether the characteristics of hydrogen gas are compatible with the natural gas pipeline infrastructure. Based on these reviews, it was found that the current NG pipeline pressure exacerbates the H₂ embrittlement; for the existing NG pipelines to be repurposed, the operating pressure should be reduced, and the pipeline material should be revised. It was found that higher strength steels can be re-used with major modifications, or the pipeline should be constructed from material grade X52 or below. Nevertheless, the fitness of the existing NG pipelines for H₂ transmission should be assessed on a case-by-case basis and other factors such as erosion, leakage, pressure cycling, monitoring (e.g., distributed fiber-optic sensing technology) and a rigorous assessment of welds and joints should also be considered. Full article

(This article belongs to the Special Issue Innovative Processes and Technologies for Energy Applications Towards Sustainability)

► Show Figures

Figure 1

36 pages, 4934 KB

Open AccessEditor’s ChoiceArticle

Protocol Proposal and Molecular Docking Mechanistic Elucidation of an Ecological Tanning Process for Fish Skin

by Marilia Inês Soares Ferrante, Juan Philippe-Teixeira, Kátia Kalko Schwarz, Daniel Pedro Willemann, Paulo Cezar Bastianello Campagnol and Márcio Vargas-Ramella

Processes 2026, 14(7), 1173; https://doi.org/10.3390/pr14071173 - 5 Apr 2026

Viewed by 918

Abstract

Chrome tanning of fish skins generates hazardous effluents and carcinogenic Cr(VI) residues; chromium-free routes to valorize collagen-rich by-products from aquaculture and coastal fisheries are therefore needed. We report a 12-stage ecological protocol employing acetic acid/NaCl pickling, Acacia mearnsii tannin, A. podalyriifolia retanning, mashed-papaya [...] Read more.

Chrome tanning of fish skins generates hazardous effluents and carcinogenic Cr(VI) residues; chromium-free routes to valorize collagen-rich by-products from aquaculture and coastal fisheries are therefore needed. We report a 12-stage ecological protocol employing acetic acid/NaCl pickling, Acacia mearnsii tannin, A. podalyriifolia retanning, mashed-papaya enzymatic bating, and cinnamon as antimicrobial/odor adjunct, scaled from bench to pilot using exclusively locally sourced inputs, for Nile tilapia (Oreochromis niloticus) and Patagonian flounder (Paralichthys patagonicus). Three trained operators evaluated macroscopic quality against five predefined criteria adapted from SATRA and ISO 3376 grading conventions, providing a structured feasibility baseline that does not substitute for the standardized instrumental testing designated as priority future work. Both species achieved satisfactory grain stability, complete tannin penetration, pliable handle, and cinnamon-dominant odor without residual amines; dark-brown coloration is a recognized practical limitation for fashion applications. In silico molecular docking (GNINA v1.0) was used to explore the mechanistic plausibility of each ecological substitution, generating testable hypotheses rather than definitive mechanistic conclusions: the multidentate polyphenol proxy (PGG) exhibited consistently superior collagen engagement over the flavanol monomer across both collagen constructs and all three scoring metrics (1CAG: Vina affinity −5.51 ± 0.13 vs. −3.54 ± 0.35 kcal/mol; CNNscore 0.874 ± 0.009 vs. 0.771 ± 0.010; 7CWK: Vina affinity −6.98 ± 1.43 vs. −4.37 ± 0.16 kcal/mol; CNNscore 0.858 ± 0.024 vs. 0.635 ± 0.094). Dipeptide probes were reproducibly accommodated in the papain catalytic cleft, with the closest configuration reaching 3.997 Å from the catalytic nucleophile (OCS25-SG). Trans-cinnamaldehyde occupied the quorum-sensing pocket with reproducible placement (CNNscore 0.718 ± 0.034) but without score-based selectivity over structural decoys, a result interpreted as hypothesis-generating for future microbiological validation. The protocol is reproducible from bench to pilot and generalizable across two species with distinct dermal architectures. Quantitative physical-mechanical testing (shrinkage temperature, tensile strength, elongation, tear load), CIELab colorimetric analysis, and effluent characterization (COD, BOD₅, total phenolics) are designated as priorities for future validation. Full article

(This article belongs to the Special Issue Chemical Insights into Food Antioxidants)

► Show Figures

Graphical abstract

30 pages, 2118 KB

Open AccessEditor’s ChoiceReview

Artificial Intelligence Enabling Intelligent Solar Energy Systems: Integration and Emerging Directions

by Rogelio Ochoa-Barragán, Luis David Saavedra-Sánchez, Fabricio Nápoles-Rivera, César Ramírez-Márquez, Luis Fernando Lira-Barragán and José María Ponce-Ortega

Processes 2026, 14(7), 1167; https://doi.org/10.3390/pr14071167 - 4 Apr 2026

Cited by 3 | Viewed by 1630

Abstract

The integration of artificial intelligence (AI) into solar energy systems has emerged as a transformative pathway to enhance efficiency, reliability, and sustainability in renewable energy. This review examines recent advances in AI-driven optimization and integration strategies across photovoltaic and solar thermal technologies with [...] Read more.

The integration of artificial intelligence (AI) into solar energy systems has emerged as a transformative pathway to enhance efficiency, reliability, and sustainability in renewable energy. This review examines recent advances in AI-driven optimization and integration strategies across photovoltaic and solar thermal technologies with elements of bibliometric analysis to identify trends, methodologies, and research directions. A particular emphasis is placed on machine learning and deep learning techniques applied to solar irradiance forecasting, maximum power point tracking, fault detection, energy management, and predictive maintenance. Unlike earlier reviews that focused on isolated applications, this work highlights the systemic role of AI in enabling smart grids, hybrid systems, and large-scale energy storage integration. The novelty of this contribution lies in mapping the evolution from traditional control methods to intelligent, self-adaptive frameworks that couple physical modeling with data-driven approaches, offering a structured roadmap for future developments. Furthermore, the review identifies challenges such as data scarcity, computational demand, and interpretability of AI models, while outlining opportunities for process intensification, resilience, and techno-economic optimization. By bridging technical progress with implementation prospects, this article provides an updated reference for researchers, policymakers, and industry stakeholders seeking to accelerate the deployment of AI-enhanced solar energy solutions. Full article

(This article belongs to the Special Issue Modeling, Simulation and Control in Energy Systems—2nd Edition)

► Show Figures

Figure 1

33 pages, 3000 KB

Open AccessEditor’s ChoiceArticle

Harnessing Oil-Contaminated Soil Microbiomes for Improved Anaerobic Digestion of Cow and Pig Manure

by Morena India Mokoena, Charles Rashama, Rosina Nkuna and Tonderayi Sylvester Matambo

Processes 2026, 14(7), 1165; https://doi.org/10.3390/pr14071165 - 3 Apr 2026

Viewed by 1052

Abstract

Anaerobic digestion (AD) of animal manures for biogas production faces challenges including nutritional imbalance, foaming, and process instability. This study evaluated bioaugmentation with surfactant-degrading microbial consortia and cell-free extracts derived from well-characterized oil-contaminated soils during cow and pig manure digestion. These previously analyzed [...] Read more.

Anaerobic digestion (AD) of animal manures for biogas production faces challenges including nutritional imbalance, foaming, and process instability. This study evaluated bioaugmentation with surfactant-degrading microbial consortia and cell-free extracts derived from well-characterized oil-contaminated soils during cow and pig manure digestion. These previously analyzed soils contained distinct microbial communities dominated by Pseudomonas in acidic, high-PAH soils and Bacillus in neutral-pH soils with genetic potential for hydrocarbon degradation. Over 30 days, six treatments were assessed using the Automatic Methane Potential Test System (AMPTS II), with pH monitoring, foaming analysis, and 16S rRNA sequencing coupled with PICRUSt2 functional prediction. Supplementation with microbial consortia and extract markedly increased cumulative biogas outputs (cow manure: 407.76 to 603.28 mL/gVS and pig manure: 403.82 to 627.5 mL/gVS), biomethane by 30–50%, reduced digestion time by 5–6 days, and improved pH stability. Foaming reduction was substrate-specific: extracts reduced foam by up to 60% in pig manure, while consortia reduced it by up to 65% in cow manure. Microbial analysis revealed enrichment of fermentative and syntrophic taxa (Clostridium sensu stricto and Paludibacter) and upregulation of methanogenesis pathways (tetrahydromethanopterin S-methyltransferase). This study illustrates that tailored bioaugmentation utilizing consortia from hydrocarbon-contaminated soils provides an environmentally sustainable method to enhance methane yields, improve stability, and control foaming in manure AD, with outcomes significantly affected by the type of manure and amendment strategy employed. Full article

(This article belongs to the Section Biological Processes and Systems)

► Show Figures

Graphical abstract

20 pages, 1116 KB

Open AccessEditor’s ChoiceArticle

Process-Integrated Optimization and Symbolic Regression for Direct Prediction of CFRP Area in Masonry Wall Strengthening

by Gebrail Bekdaş, Ammar Khalbous, Sinan Melih Nigdeli and Ümit Işıkdağ

Processes 2026, 14(7), 1163; https://doi.org/10.3390/pr14071163 - 3 Apr 2026

Viewed by 612

Abstract

Unreinforced masonry walls exhibit limited resistance to lateral loads and, therefore, frequently require strengthening interventions. Carbon fiber reinforced polymer (CFRP) systems provide an efficient retrofit solution; however, current design procedures defined in structural guidelines require repetitive trial calculations to determine the necessary reinforcement [...] Read more.

Unreinforced masonry walls exhibit limited resistance to lateral loads and, therefore, frequently require strengthening interventions. Carbon fiber reinforced polymer (CFRP) systems provide an efficient retrofit solution; however, current design procedures defined in structural guidelines require repetitive trial calculations to determine the necessary reinforcement amount. This study introduces a hybrid computational process that integrates metaheuristic optimization with symbolic regression to generate direct analytical equations for the estimation of the required CFRP area. First, a comprehensive database containing 1300 optimal strengthening scenarios was generated using the Jaya optimization algorithm under the constraints specified in ACI 440.7R and ACI 530. The resulting dataset was subsequently processed through symbolic regression using the PySR platform to identify explicit mathematical relationships between structural parameters and the optimum CFRP area. Most traditional machine learning approaches operate as black-box predictors. In contrast, the proposed approach generates interpretable closed-form expressions that can be used directly in engineering calculations. Two models were derived from the Pareto-optimal solution set. The first model is a simplified equation emphasizing algebraic simplicity. The second model prioritizes prediction accuracy. The simplified formulation achieved a coefficient of determination of approximately 0.992. The accuracy-focused model achieved a value above 0.997 with very low prediction errors. Validation studies with independent test samples showed that the obtained equations are reliable. The average error for the simplified model is below 4%, and for the high-accuracy model, it is approximately 2%. The results demonstrate that combining the optimization-generated datasets with symbolic regression makes it possible to obtain transparent design equations. These equations eliminate iterative design processes and provide a fast and reliable estimation tool for CFRP strengthening of masonry walls. Full article

(This article belongs to the Special Issue Advanced Functional Materials Design and Computation)

► Show Figures

Figure 1

17 pages, 1106 KB

Open AccessEditor’s ChoiceArticle

Glucose and Xylose Production Under a Biorefinery Approach: Essential Oil Extraction, Hydrolysis of Orange Residues, and Reaction Kinetics at Pilot Scale

by Edson E. Armenta, Marcos A. Coronado, José R. Ayala, Jesús M. Armenta, Daniela G. Montes and Benjamín A. Rojano

Processes 2026, 14(7), 1154; https://doi.org/10.3390/pr14071154 - 3 Apr 2026

Viewed by 565

Abstract

The orange juice industry generates large amounts of waste, leading to significant environmental impacts. Within the framework of a citrus biorefinery, this study evaluates an integrated pilot-scale scheme combining essential oil extraction with hydrolysis of orange waste. A self-designed modular system was used, [...] Read more.

The orange juice industry generates large amounts of waste, leading to significant environmental impacts. Within the framework of a citrus biorefinery, this study evaluates an integrated pilot-scale scheme combining essential oil extraction with hydrolysis of orange waste. A self-designed modular system was used, characterized by ease of operation and maintenance, consisting of a 20 L sealed reactor and a condenser with water recirculation. Essential oil extraction was carried out by hydrodistillation, producing 35 mL of essential oil per run and a yield of 2.57 mL per 100 g of orange peel. Hydrolysis was investigated using a 2³ factorial design considering time (30 and 60 min), waste type (with and without pulp), and H₂SO₄ concentration (0 and 0.25% v/v). ANOVA results showed that the waste type was the dominant factor, while the acid concentration had no significant effect. The optimal hydrolysis condition was waste with pulp, 0% acid, and 30 min, achieving 108.5 g/L of glucose and 30.4 g/L of xylose. Under these conditions, the kinetics of glucose and xylose release were determined. The energy consumption was 45.96 MJ, equivalent to 70.61 kJ/g of glucose and 236.59 kJ/g of xylose, with corresponding costs of 0.0017 and 0.0057 USD/g, respectively. Orange waste containing pulp, obtained directly from juice-processing facilities, exhibits greater valorization potential than orange waste without pulp to produce essential oil, glucose, and xylose within a biorefinery scheme. Full article

(This article belongs to the Special Issue Biomass Energy Conversion for Efficient and Sustainable Utilization)

► Show Figures

Figure 1

24 pages, 5578 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Comparison of Pulsed and Continuous Ultrasound-Assisted Electrocoagulation and Zeolite Integration: Assessment of a Hybrid Wastewater Treatment Approach

by Ivona Čule, Nediljka Vukojević Medvidović, Ladislav Vrsalović, Sandra Svilović and Senka Gudić

Processes 2026, 14(7), 1152; https://doi.org/10.3390/pr14071152 - 3 Apr 2026

Cited by 1 | Viewed by 831

Abstract

This study compares the effects of pulsed and continuous ultrasound at two frequencies (28 and 40 kHz) on hybrid electrocoagulation (EC) systems for the treatment of compost wastewater, combining zeolite addition with different electrode pairs (Al/Al, Fe/Fe, Zn/Zn, and Al/Fe). The experimental investigation [...] Read more.

This study compares the effects of pulsed and continuous ultrasound at two frequencies (28 and 40 kHz) on hybrid electrocoagulation (EC) systems for the treatment of compost wastewater, combining zeolite addition with different electrode pairs (Al/Al, Fe/Fe, Zn/Zn, and Al/Fe). The experimental investigation addressed four complementary aspects: (i) effluent quality and treatment efficiency evaluation through solution parameters monitoring, (ii) electrode degradation assessment through mass loss measurements and surface analysis, (iii) sedimentation analysis, and (iv) operational costs evaluation in terms of electrode and energy consumption. Process optimization was conducted using a mixed Taguchi L8 design to quantify the combined influence of electrode pairs, ultrasound mode and frequency, zeolite addition, and treatment time on pollutant removal and electrode wear. Operational cost calculation demonstrated that electrode material, ultrasound mode, and frequency, along with applied current and voltage, collectively govern electrode wear and Faraday efficiency, with pulsed ultrasound at 40 kHz and Al electrodes minimizing anodic mass loss and energy consumption. The Taguchi analysis revealed that zeolite addition is the most influential factor negatively affecting COD and turbidity. Meanwhile, the optimal operational parameters for overall performance were identified as an Al/Al electrode pair, a 40 kHz ultrasound frequency, pulsed mode, a 10 min treatment time, and the absence of zeolite. These findings provide practical guidance for designing hybrid pulsed ultrasound EC processes that are both effective and economically sustainable for complex wastewater treatment. Full article

(This article belongs to the Special Issue Advanced Photocatalytic and Electrochemical Processes for Water and Wastewater Treatment)

► Show Figures

Figure 1

18 pages, 1150 KB

Open AccessEditor’s ChoiceArticle

Measurement of Biomass in Small-Scale Microalgal and Microalgal–Bacterial Systems for Wastewater Treatment: Mini Review and Experimental Evaluation

by Amrita Ranjan, Philadelphia V. Ngobeni and Pamela Jean Welz

Processes 2026, 14(7), 1145; https://doi.org/10.3390/pr14071145 - 2 Apr 2026

Cited by 2 | Viewed by 981

Abstract

Accurate biomass quantification is important for evaluating growth kinetics and performance of microalgal and microalgal–bacterial wastewater treatment systems. However, small-scale studies frequently encounter methodological limitations due to low biomass concentrations, limited sampling volumes, and/or interference from non-biotic solids in complex wastewaters. This work [...] Read more.

Accurate biomass quantification is important for evaluating growth kinetics and performance of microalgal and microalgal–bacterial wastewater treatment systems. However, small-scale studies frequently encounter methodological limitations due to low biomass concentrations, limited sampling volumes, and/or interference from non-biotic solids in complex wastewaters. This work adopts a two-fold approach: (i) a concise review of current biomass quantification methods for bench-scale systems, and (ii) an experimental evaluation of a gravimetric protocol for complex wastewaters. The review discusses commonly applied techniques, highlights their strengths and weaknesses, and identifies research gaps in data comparability and reproducibility. The laboratory investigations evaluated the effects of key factors, namely culture volume (250 mL to 1 L), test aliquots (2.5 mL to 10 mL), and the absolute weight of total suspended solids (3.43 g to 14.5 g) on total suspended solids measurements. Aliquots containing <5 mg total suspended solids produced statistically significant variability, whereas reliable and reproducible results were obtained when >8–10 mg absolute total suspended solids per aliquot was present. In complex wastewater matrices, approximately 18% of total suspended solids consisted of non-volatile solids, demonstrating that the method can systematically over-estimate true dry cell weight in microalgal–bacterial systems. The findings emphasized the need for procedural standardization. Finally, a practical gravimetric protocol is proposed for both axenic and consortium-based small-scale studies dealing with complex wastewater, providing an evidence-based roadmap for obtaining more reliable biomass estimations. Full article

(This article belongs to the Special Issue Applications of Microorganisms in Wastewater Treatment)

► Show Figures

Graphical abstract

41 pages, 7425 KB

Open AccessEditor’s ChoiceReview

Advancements in Plastic Waste Sorting: A Review of Techniques and Applications

by Felipe Anchieta e Silva, Amélia de Santana Cartaxo, Antônio Demouthié de Sales Rolim Esmeraldo, Elaine Meireles Senra and José Carlos Pinto

Processes 2026, 14(7), 1144; https://doi.org/10.3390/pr14071144 - 2 Apr 2026

Cited by 2 | Viewed by 2485

Abstract

The widespread utilization of plastic materials across various industrial sectors drives a continuous increase in global polymer demand. The exponential production growth generates severe environmental challenges regarding municipal solid waste management, as substantial fractions of post-consumer residuals enter landfills due to limited recycling [...] Read more.

The widespread utilization of plastic materials across various industrial sectors drives a continuous increase in global polymer demand. The exponential production growth generates severe environmental challenges regarding municipal solid waste management, as substantial fractions of post-consumer residuals enter landfills due to limited recycling infrastructure. Mitigating the global environmental burden requires the implementation of advanced recovery strategies to transition polymer waste into viable secondary feedstocks. Consequently, deploying efficient sorting techniques constitutes a fundamental requirement to integrate plastic materials into formal waste management protocols and optimize recycling yields. Technological innovations currently drive the transition from traditional manual segregation towards highly sophisticated automated sensor-based sorting architectures, maximizing separation efficiency. In this context, the present study comprehensively reviews pretreatment classification techniques engineered to fractionate heterogeneous waste streams into high-purity material flows. Rather than restricting the analysis to polyolefins, this review encompasses a broad spectrum of commodity polymers predominantly found in urban solid waste environments. Full article

(This article belongs to the Special Issue Circular Economy in Process Engineering: Impact Assessment and Directions for Sustainability)

► Show Figures

Graphical abstract

18 pages, 2140 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Development and Valorization of Bioenergy Briquettes Using Agro-Industrial Residues from a Semi-Arid Region

by Víctor Daniel Núñez-Retana, Mirna Lugo-Rodríguez, Alondra Reyes-Morales, Artemio Carrillo-Parra, Heriberto de Jesus Maldonado-Quiñones, Maginot Ngangyo-Heya and Juan García-Quezada

Processes 2026, 14(7), 1138; https://doi.org/10.3390/pr14071138 - 1 Apr 2026

Viewed by 802

Abstract

The valorization of agro-industrial residues for solid biofuel production represents a sustainable strategy to meet energy demand, reduce open-field burning, and mitigate environmental impacts. This study aimed to assess the feasibility of producing high-quality briquettes from agro-industrial residues such as oregano stems, pecan [...] Read more.

The valorization of agro-industrial residues for solid biofuel production represents a sustainable strategy to meet energy demand, reduce open-field burning, and mitigate environmental impacts. This study aimed to assess the feasibility of producing high-quality briquettes from agro-industrial residues such as oregano stems, pecan shells, and peanut shells sourced from a semi-arid region of northern Mexico. Raw materials were obtained from local industries, processed, and characterized through proximate analysis and determination of higher heating value (HHV). Briquettes were manufactured under various compaction pressures and temperatures without the use of binders, and their physical and energy properties were evaluated according to international standards. Results indicated that all briquette types met Class A quality standards, with moisture contents between 6 and 9%, ash contents below 6%, and HHVs ranging from 18.9 to 21.0 MJ kg⁻¹. Pecan shell briquettes exhibited the highest particle density (1.18 g cm⁻³), while peanut shell briquettes demonstrated superior mechanical performance and the highest Impact Resistance Index (97% and 200, respectively). Oregano stem briquettes showed lower densities but maintained satisfactory energy properties (19.5 MJ kg⁻¹). Beyond its energy potential, this valorization approach contributes to local economic development, reduces environmental pollution, and decreases dependence on firewood in rural communities. Full article

(This article belongs to the Special Issue Process-Based Valorization of Agro-Industrial Residues for Sustainable and Circular Systems)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Editor’s Choice Articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI