ChemEngineering

28 pages, 2966 KB

Open AccessArticle

Valorization of Waste Cooking Oils into Antimicrobial Soaps with Honey, Propolis, and Essential Oils

by Mirel Glevitzky, Gabriela-Alina Dumitrel, Ana-Maria Pană, Gerlinde Iuliana Rusu, Mihai-Teopent Corcheş and Mihaela Laura Vică

ChemEngineering 2026, 10(2), 31; https://doi.org/10.3390/chemengineering10020031 - 11 Feb 2026

Viewed by 1475

Abstract

The valorization of waste cooking oils (WCOs) provides a strategy to reduce environmental impact while converting residues from the food industry into valuable products. This study developed and characterized antimicrobial soaps from purified WCOs (sunflower, palm, and pumpkin oils) enriched with natural bioactive [...] Read more.

The valorization of waste cooking oils (WCOs) provides a strategy to reduce environmental impact while converting residues from the food industry into valuable products. This study developed and characterized antimicrobial soaps from purified WCOs (sunflower, palm, and pumpkin oils) enriched with natural bioactive ingredients. WCOs were purified by filtration, treatment with 10% NaCl, and bleaching with 3% H₂O₂, followed by cold saponification with NaOH. Twelve soap formulations were prepared, including six enriched with bee products (propolis, poly-floral honey, linden, acacia, honeydew, and sunflower) and six enriched with essential oils (EOs) (clove, rosemary, mace, nutmeg, white pepper, and juniper). The WCOs, natural bioactive ingredients, and soaps were characterized using physico-chemical methods (FTIR, GC-FID, phenols, flavonoids, etc.), while their antibacterial activity was determined against two microbial strains: Staphylococcus aureus and Escherichia coli. The antimicrobial activity of soaps is related to their alkaline pH, while the addition of honey, propolis, or EOs contributes to additional antimicrobial effects. Among honey- and propolis-enriched soaps, those with propolis produced the largest inhibition zones (up to 8.67 mm for S. aureus and 7.0 mm for E. coli). EO-based soaps exhibited higher activity, with rosemary EO-based soap showing the largest zones (up to 9.5 mm for S. aureus and 7.5 mm for E. coli). These data support the potential of enriched soaps containing honey, propolis, and EOs for antimicrobial applications, highlighting their value as a sustainable alternative in the valorization of WCOs. Full article

(This article belongs to the Special Issue Innovative Approaches for the Environmental Chemical Engineering)

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20 pages, 1848 KB

Open AccessArticle

Adsorption of Perfluorooctanoic Acid from Aqueous Media Using an Engineered Sugarcane Bagasse Biochar–Chitosan Composite

by K. Pavithra and Paromita Chakraborty

ChemEngineering 2026, 10(2), 30; https://doi.org/10.3390/chemengineering10020030 - 11 Feb 2026

Viewed by 905

Abstract

In the recent years, several studies from developing economies have reported the presence of per- and polyfluoroalkyl substances (PFAS) in water bodies, with perfluorooctanoic acid (PFOA) predominating, a potential endocrine disruptor. In this study, an engineered sugarcane bagasse biochar–chitosan composite (SBCT) was designed, [...] Read more.

In the recent years, several studies from developing economies have reported the presence of per- and polyfluoroalkyl substances (PFAS) in water bodies, with perfluorooctanoic acid (PFOA) predominating, a potential endocrine disruptor. In this study, an engineered sugarcane bagasse biochar–chitosan composite (SBCT) was designed, synthesized, and evaluated as a novel adsorbent for the removal of PFOA from aqueous systems at concentrations up to 500 ppb. Batch adsorption experiments were conducted to investigate the effects of initial PFOA concentration, contact time, pH, adsorbent dosage, and temperature. Scanning electron microscopy (SEM) showed that SBCT has a significant porous structure. The composite showed over 90% of PFOA removal from water. Further, peaks corresponding to C–F bonds observed after adsorption by Fourier transform infrared (FTIR) spectroscopy confirms the adsorption of PFOA on SBCT. The protonated amine groups (NH₃⁺) in chitosan enhanced the adsorption of anionic PFOA through electrostatic attraction with carboxyl groups (COO⁻). The kinetic study revealed that pseudo-first-order best described the adsorption process, with an equilibrium adsorption capacity (q_eq) of 2.78 mg/g, suggesting that physisorption is the predominant mechanism. The Langmuir Isotherm model gave the best fit, establishing a maximum adsorption capacity (q_max) of 9.08 mg/g. Thermodynamic analysis revealed that the adsorption process was spontaneous and exothermic, consistent with physisorption. The regeneration capacity of the SBCT composite demonstrated exceptional reusability over five methanol adsorption–desorption cycles. The adsorption kinetics, equilibrium behavior, and regeneration efficiency suggest that SBCT is a viable low-cost adsorbent for batch adsorption-based treatment systems targeting PFOA removal, particularly in decentralized and resource-constrained water treatment applications. Full article

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19 pages, 5382 KB

Open AccessArticle

The Role of a SiC Sublayer in Modulating the Electrochemical Behavior of Co_xS_y/SiC Heterostructure Supercapacitor Electrodes

by Tatiana A. Moiseeva, Inna Yu. Bogush, Oleg I. Il’in, Alexey N. Yatsenko, Rajathsing Kalusulingam and Tatiana N. Myasoedova

ChemEngineering 2026, 10(2), 29; https://doi.org/10.3390/chemengineering10020029 - 10 Feb 2026

Viewed by 678

Abstract

In this study, we investigated the electrochemical properties and performance characteristics of Co_xS_y and silicon–carbon-based heterostructures synthesized on nickel foam substrates for energy storage applications. Cobalt sulfide films were successfully electrodeposited on nickel foam (NF) using cyclic voltammetry (CV) from [...] Read more.

In this study, we investigated the electrochemical properties and performance characteristics of Co_xS_y and silicon–carbon-based heterostructures synthesized on nickel foam substrates for energy storage applications. Cobalt sulfide films were successfully electrodeposited on nickel foam (NF) using cyclic voltammetry (CV) from the solutions with different Co²⁺ concentrations. The presence of a silicon–carbon sublayer promotes the deposition of cobalt sulfide material. The amorphous phase of α-CoS was observed by the X-ray diffraction technique. Raman spectroscopy confirmed the formation of CoS and CoS₂ phases. A significant increase in electrode areal capacitance is observed with the silicon–carbon film sublayer from 0.5 to 1.3 F·cm⁻² and from 1.6 to 2.3 F·cm⁻² at 3 mA·cm⁻² for samples prepared from solutions with CoCl₂·6H₂O concentrations of 0.005 M and 0.02 M, respectively. In the case of gravimetric capacitance, an increase is observed in the presence of a silicon–carbon sublayer for the SiC@CoS_0.005 sample, rising from 690 F·g⁻¹ to 748 F·g⁻¹ at 4 A·g⁻¹. Conversely, the SiC@CoS_0.02 sample shows a decrease from 1287 F·g⁻¹ to 6590 F·g⁻¹. It was shown that the capacitance of all the electrodes derives from the mix of diffusion-controlled and surface-controlled capacitance processes. The electrochemical impedance spectroscopy (EIS) analysis indicates that the formation of heterostructure materials significantly alters the electrochemical properties by reducing both R_f and R_s. Full article

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24 pages, 4714 KB

Open AccessArticle

Structure-Based Screening and Molecular Dynamics of Rifampicin Analogues Targeting InhA of Mycobacterium tuberculosis

by Lucas Paul and Andrew S. Paluch

ChemEngineering 2026, 10(2), 28; https://doi.org/10.3390/chemengineering10020028 - 6 Feb 2026

Viewed by 729

Abstract

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a global health burden, particularly due to multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains. Rifampicin, a frontline anti-TB drug that inhibits RNA polymerase, has been central to therapy, but rpoB mutations compromise its efficacy. This [...] Read more.

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a global health burden, particularly due to multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains. Rifampicin, a frontline anti-TB drug that inhibits RNA polymerase, has been central to therapy, but rpoB mutations compromise its efficacy. This highlights the need for Rifampicin analogues that target alternative enzymes to sustain therapeutic effectiveness. In this study, a structure-based computational approach was employed to screen Rifampicin analogues against enoylacyl carrier protein reductase (InhA), a validated enzyme in the biosynthesis of mycolic acids. A library of 399 analogues was retrieved from SwissSimilarity and evaluated using ADMET analysis, with the best candidates showing favourable pharmacokinetic profiles and compliance with Lipinski’s Rule of Five. Molecular docking identified ZINC000013629834 (−10.90 kcal/mol) and ZINC000253411694 (−10.36 kcal/mol) as superior to Rifampicin (−9.05 kcal/mol), with ILE21, SER20, and THR196 consistently stabilizing interactions. Molecular dynamics simulations confirmed the stability of the complexes, with RMSD values of 0.167 nm, 0.175 nm, and 0.297 nm for ZINC000013629834, ZINC000253411694, and Rifampicin, respectively. MM/PBSA analysis showed comparable binding free energies. These findings suggest that optimized Rifampicin analogues targeting InhA may overcome rpoB-associated resistance and serve as promising leads for next-generation anti-TB drug development. Full article

(This article belongs to the Special Issue New Trends in (Bio)chemical Engineering: Biobased Pharmaceutical Processes)

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22 pages, 7747 KB

Open AccessArticle

Crack the Shell by Unlocking the Polyphenol Power of Hazelnut Waste with Ultrasound

by Jana Šic Žlabur, Margareta Đumbir, Anamarija Peter, Jona Šurić, Sandra Voća, Martina Skendrović Babojelić, Filip Varga and Mia Dujmović

ChemEngineering 2026, 10(2), 27; https://doi.org/10.3390/chemengineering10020027 - 6 Feb 2026

Viewed by 1022

Abstract

Hazelnut (Corylus avellana L.) shells, typically discarded as agro-industrial by-products, represent a potentially valuable source of bioactive polyphenolic compounds with significant antioxidant properties. This study aimed to evaluate and compare the polyphenol composition and antioxidant capacity of the kernels and shells of [...] Read more.

Hazelnut (Corylus avellana L.) shells, typically discarded as agro-industrial by-products, represent a potentially valuable source of bioactive polyphenolic compounds with significant antioxidant properties. This study aimed to evaluate and compare the polyphenol composition and antioxidant capacity of the kernels and shells of two hazelnut varieties, ‘Rimski’ and ‘Istarski duguljasti’. High-intensity ultrasound-assisted extraction (UAE) was applied to enhance the recovery of bioactive compounds under optimized conditions (80% ethanol, high amplitude, and 25 min treatment). The extracts were analyzed for total polyphenols, total flavonoids, total non-flavonoids, and individual phenolic compounds. Hazelnut shells exhibited significantly higher levels of total polyphenols, flavonoids, and antioxidant capacity compared to kernels. The dominant individual polyphenolic compounds identified in the shell were kaempferol, gallic acid, naringin, rutin trihydrate, quercetin-3-glucoside, chlorogenic acid, quercetin, ferulic acid, rosmarinic acid, and vanillic acid. Application of UAE notably improved extraction efficiency and overall yield compared to conventional extraction methods. The findings underscore hazelnut shells as a nutritionally and functionally valuable by-product and confirm UAE as a green, efficient extraction technique. These results provide a strong basis for developing high-value-added products for the cosmetic, pharmaceutical, and food industries, thereby supporting circular bioeconomy and sustainable chemistry principles. Full article

(This article belongs to the Special Issue Advances in Sustainable and Green Chemistry)

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16 pages, 3223 KB

Open AccessArticle

Performance Evaluation of Nano Ag/Co Modified Hydroxyapatite Catalyst Synthesized via Dielectric Barrier Discharge for Highly Efficient Toluene Oxidation

by Shu-Yao Zhang, Xue-Min Wang, En-Peng Deng, Ya-Ni Zhang, Hui Zhu, Qiang Chen, Si-Wen Pan and Yu-Xin Miao

ChemEngineering 2026, 10(2), 26; https://doi.org/10.3390/chemengineering10020026 - 5 Feb 2026

Viewed by 553

Abstract

In this study, a series of Ag/Co-HA catalysts were synthesized using a plasma-assisted method. Plasma is a partially ionized gas composed of electrons, ions, neutral molecules, free radicals, photons, and excited-state substances, which can serve as a highly reactive medium for catalyst modification. [...] Read more.

In this study, a series of Ag/Co-HA catalysts were synthesized using a plasma-assisted method. Plasma is a partially ionized gas composed of electrons, ions, neutral molecules, free radicals, photons, and excited-state substances, which can serve as a highly reactive medium for catalyst modification. Its unique discharge characteristics can effectively regulate the dispersion of active sites, electronic structure, and metal–support interactions. The study compared the performance of catalysts prepared by the traditional high-temperature calcination method with those treated by rapid plasma in the toluene oxidation removal reaction. The results showed that the catalyst treated by dielectric barrier discharge (DBD) plasma exhibited excellent low-temperature catalytic activity, achieving 100% toluene conversion and approximately 75% CO₂ selectivity at 275 °C, while the catalyst prepared by traditional calcination only achieved 73% toluene conversion and approximately 50% CO₂ selectivity at 285 °C. This study provides a simple preparation method for the Ag/5Co-HA-P catalyst. Due to the plasma treatment’s ability to precisely control the catalyst structure, along with advantages such as low energy consumption, short processing time, and environmental friendliness, it holds significant application prospects in the field of VOCs treatment. Full article

(This article belongs to the Special Issue Advanced Functional Materials and Interfaces for Electrochemical Energy Storage and Environmental Catalysis)

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24 pages, 1974 KB

Open AccessReview

Catalytic Oxidation of Alkanes and Cycloalkanes: Overview

by Aygun Zabit Aliyeva, Ulviyya Aliman Karimova, Sahib Gadji Yunusov, Michael Vigdorowitsch and Sevinj Abdulhamid Mammadkhanova

ChemEngineering 2026, 10(2), 25; https://doi.org/10.3390/chemengineering10020025 - 3 Feb 2026

Viewed by 2054

Abstract

Selective functionalisation of inert C(sp³)–H bonds in alkanes and cycloalkanes remains one of the main challenges in the field of environmentally sustainable chemistry. This review provides a critical assessment of current catalytic strategies, in particular addressing the persistent problem of overoxidation [...] Read more.

Selective functionalisation of inert C(sp³)–H bonds in alkanes and cycloalkanes remains one of the main challenges in the field of environmentally sustainable chemistry. This review provides a critical assessment of current catalytic strategies, in particular addressing the persistent problem of overoxidation and low selectivity. Going beyond traditional compartmentalised summaries, this work identifies a significant trend towards the integration of non-traditional activation methods, including ultrasonic cavitation, photocatalysis, and nanosecond pulse discharges, in both homogeneous and heterogeneous systems. Key contributions include a comparative analysis of radical control strategies, in particular highlighting how intermediate hydroperoxides can be used to shift reaction pathways towards selectivity of over 97% for alcohols and ketones. In addition, we discuss the emerging role of carbon nanomaterials (e.g., fullerenes and brominated nanotubes) as active electron-rich carriers and catalysts that lower the energy barriers for C–H activation under mild, ‘green’ conditions. The review concludes that the future of scalable hydrocarbon oxidation lies in ‘hybrid’ approaches such as stabilising active metal centres in protective matrices (zeolites, polymers) while using physical stimuli (ultrasound) to overcome diffusion limitations. This unique perspective highlights the transition from purely chemical catalyst design to integrated process intensification, offering a roadmap for energy-efficient and environmentally friendly industrial technologies. Full article

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19 pages, 8765 KB

Open AccessArticle

Kinetics of Decomposition in Alkaline Media NaOH and Ca(OH)₂ of Thallium Jarosite

by Hernán Islas, J. Eliecer Méndez, Francisco Patiño, Sayra Ordoñez, Iván A. Reyes, Paola B. Bocardo, Martín Reyes, Miriam Estrada and Mizraim U. Flores

ChemEngineering 2026, 10(2), 24; https://doi.org/10.3390/chemengineering10020024 - 3 Feb 2026

Viewed by 947

Abstract

Thallium is one of the most toxic elements on the planet, and one alternative method for its precipitation is through jarosite-type compounds. Therefore, in this work, the kinetics of thallium jarosite were evaluated in an alkaline medium (NaOH and Ca(OH)₂). Experiments [...] Read more.

Thallium is one of the most toxic elements on the planet, and one alternative method for its precipitation is through jarosite-type compounds. Therefore, in this work, the kinetics of thallium jarosite were evaluated in an alkaline medium (NaOH and Ca(OH)₂). Experiments were conducted to assess the effect of medium concentration from 0.03 M to 5.5 × 10⁻⁴ M and the effect of temperature from 20 °C to 60 °C. The sigmoidal curves showed an induction period, during which there was no release of sulfur or thallium ions into the solution, nor the formation of solid byproducts, according to the X ray diffraction (XRD) results. Similarly, a progressive conversion period was observed, evidenced by the release of sulfur and thallium ions into the solution and the formation of amorphous solids. Finally, a stability zone is reached, indicating that the decomposition reaction has ended, as there are no changes in the concentration of sulfur and thallium ions in the solution. The reaction was monitored by determining S using Inductively Coupled Plasma (ICP). The experimental results for the progressive conversion period show a better fit to the chemically controlled shrinking core kinetic model. The reaction order for the kinetics in NaOH medium is 1.09 for the induction period and 0.89 for the progressive conversion period, while for Ca(OH)₂ medium it is 0.78 for the induction period and 0.47 for the progressive conversion period. The activation energies for the progressive conversion period in the two proposed media are 91.87 kJ mol⁻¹ in NaOH and 71.14 kJ mol⁻¹ in Ca(OH)₂, indicating that the controlling mechanism in both systems is the chemical reaction. For the induction period, the activation energies are 101.52 kJ mol⁻¹ and 79.45 kJ mol⁻¹, respectively, indicating that the chemical reaction also controls the initiation of the reactions. The high activation energy in both reaction media suggests that high concentrations of OH⁻ and high temperatures are required to initiate the decomposition reaction. Thallium jarosite precipitates a large amount of thallium and requires high energy to decompose, so it could be a viable alternative in thallium retention. Full article

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24 pages, 2451 KB

Open AccessArticle

Calculation, Measurement and Validation for Estimating the Biomass of the Biofilm on Microcarriers

by Tamás Kloknicer, Gergő Bálint Sárfi, Dániel Benjámin Sándor and Anita Szabó

ChemEngineering 2026, 10(2), 23; https://doi.org/10.3390/chemengineering10020023 - 2 Feb 2026

Viewed by 633

Abstract

Traditional carriers play a major role in wastewater treatment worldwide due to their reliability, ease of production, well-established analytical methods, and strong treatment performance. Recent studies indicate that polyvinyl-alcohol-based microcarriers may surpass conventional media, as their smaller size, higher porosity, and increased specific [...] Read more.

Traditional carriers play a major role in wastewater treatment worldwide due to their reliability, ease of production, well-established analytical methods, and strong treatment performance. Recent studies indicate that polyvinyl-alcohol-based microcarriers may surpass conventional media, as their smaller size, higher porosity, and increased specific surface area enable them to retain substantially more biomass within reactors. However, their practical application remains limited because fewer analytical methods and studies exist for these materials, largely due to their small dimensions and heat sensitivity, and their behaviour under industrial conditions—including their kinetics—has yet to be fully characterised and validated. This study aims to address these gaps by reviewing existing biomass measurement standards and highlighting their limitations when applied to microcarriers and by proposing alternative experimental approaches better suited for evaluating biomass on such sensitive yet high-capacity carriers. We present a set of experimental methods (still subject to further refinement) that demonstrate reliable performance with these materials, and to validate our approach, we quantified biomass in both in vitro systems and containerised-scale technologies, reaching up to 14 kg/m³ during winter and 8.7 kg/m³ in spring. Laboratory-scale experiments showed that both heterotrophic and autotrophic cultures can achieve high biomass levels of up to 21 kg/m³ and 16 kg/m³, respectively. Heterotrophs exhibited lower growth inhibition under shear stress, while autotrophs displayed a distinct shear-force niche around 0.09 µN within the reactor. Full article

(This article belongs to the Special Issue Advances in Chemical Engineering and Wastewater Treatment)

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19 pages, 4096 KB

Open AccessArticle

Kinetics of Propene Oxidation to Acrolein over Bismuth Molybdates

by Tomislav Penović, Vesna Tomašić, Aleksandra Sander, Stanislav Kurajica and Zoran Gomzi

ChemEngineering 2026, 10(2), 22; https://doi.org/10.3390/chemengineering10020022 - 2 Feb 2026

Viewed by 757

Abstract

The conversion of alkanes/alkenes into useful intermediates is highly important in the chemical industry. In this study, the physicochemical properties and catalytically active forms of bismuth molybdates (BiMo) were investigated using the selective oxidation of propene to acrolein as a model reaction. The [...] Read more.

The conversion of alkanes/alkenes into useful intermediates is highly important in the chemical industry. In this study, the physicochemical properties and catalytically active forms of bismuth molybdates (BiMo) were investigated using the selective oxidation of propene to acrolein as a model reaction. The catalysts were prepared by two methods, coprecipitation and spray-drying, with emphasis on spray-drying. The catalysts were characterized using X-ray diffraction, N₂ adsorption/desorption isotherms, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The catalytic properties of the BiMo samples were studied in a conventional fixed-bed reactor operated under different reaction conditions. The one-dimensional (1D) pseudohomogeneous model was applied to describe the obtained experimental results. The experimental kinetic data were correlated with two complex kinetic models based on multiple reactions (parallel and serial reaction systems). The proposed models were verified by comparing computer simulation data with experimental laboratory results. This study aimed to extend the understanding of the relationship between catalyst composition/structure and catalyst activity/selectivity for different BiMo structures, and to propose kinetic models using two approaches based on parallel and series reactions, in line with efforts to improve the valorization of light olefins. Full article

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24 pages, 3277 KB

Open AccessArticle

Yttrium Sulfate Recovery Using Ethanol as Antisolvent in a Fluidized Bed Reactor

by Jacolien Sussens, Jemitias Chivavava and Alison E. Lewis

ChemEngineering 2026, 10(2), 21; https://doi.org/10.3390/chemengineering10020021 - 2 Feb 2026

Viewed by 655

Abstract

Antisolvent crystallization is a promising method for recovering rare earth elements (REEs). While it offers high theoretical yields of Y₂(SO₄)₃·nH₂O from aqueous leach solutions, the recovery is constrained by kinetic limitations. This study examined the [...] Read more.

Antisolvent crystallization is a promising method for recovering rare earth elements (REEs). While it offers high theoretical yields of Y₂(SO₄)₃·nH₂O from aqueous leach solutions, the recovery is constrained by kinetic limitations. This study examined the crystallization of Y₂(SO₄)₃·nH₂O in a fluidized bed reactor (FBR) using ethanol, focusing on the effects of the organic-to-aqueous (O/A) ratio and flow rates on yield and crystal properties. O/A ratios of 0.9 and 1.1 were investigated with an initial Y³⁺ concentration of 0.87 g/L and a crystallization time of 3 h. The system exhibits multiple rate-limiting steps. At low O/A ratios (0.9), extended induction times indicate either nucleation rate-limitations despite high supersaturation or the possible formation of an initial metastable phase, requiring extended crystallization time for near-equilibrium yields. At high O/A (1.1), elevated supersaturation accelerates nucleation and achieves ~82% yield in 3 h; however, crystal growth exhibited a remaining rate limitation. Lower supersaturation and slower mixing at O/A = 0.9 favored growth, producing crystals with D50 > 34 µm. This work explores how operational parameters influence crystallization behavior while achieving practical yields and acceptable crystal characteristics within a reasonable timeframe. The FBR provided controlled operation, enabling consistent product formation and process flexibility. Full article

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19 pages, 2797 KB

Open AccessArticle

Enhancing Operational Reliability in Industrial PTA Oxidation Reactors Using a Robust Cascade Control Scheme

by Andri Kapuji Kaharian, Theo Adiwinata, Riezqa Andika and Abdul Wahid

ChemEngineering 2026, 10(2), 20; https://doi.org/10.3390/chemengineering10020020 - 2 Feb 2026

Viewed by 609

Abstract

Maintaining stable pressure in the oxidation–compressor section of purified terephthalic acid (PTA) plants is essential for ensuring efficient and reliable operation. Conventional single-loop proportional integral derivative (PID) controllers frequently perform inadequately because of the large pressure drop between the compressor discharge and reactor [...] Read more.

Maintaining stable pressure in the oxidation–compressor section of purified terephthalic acid (PTA) plants is essential for ensuring efficient and reliable operation. Conventional single-loop proportional integral derivative (PID) controllers frequently perform inadequately because of the large pressure drop between the compressor discharge and reactor inlet, which should ideally remain at approximately 1.2 kg/cm² above the reactor pressure setpoint but can reach up to 2.8 kg/cm² due to downstream vapor-phase disturbances. Through this study, we aimed to address this issue by developing a robust cascade pressure control strategy to improve pressure stability and reduce energy losses. Dynamic process models were constructed using system identification techniques to represent real plant behavior, and the best-performing models—identified based on minimum root mean square error (RMSE)—were determined using the Wade method for pressure indicating controller PIC-101, the Lilja method for PIC-102, and the Smith method for pressure differential indicating controller PDIC-101. The proposed cascade configuration was tuned using the Lopez ISE method and evaluated under representative disturbance scenarios. The results showed that the cascade controller significantly improved pressure control, enhanced disturbance rejection, and lowered the risk of reactor shutdowns compared with the conventional proportional-integral PI-based approach. Overall, this study demonstrated that model-driven cascade control can enhance robustness, operational reliability, and energy efficiency in large-scale PTA oxidation processes. Full article

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15 pages, 1948 KB

Open AccessArticle

Advanced Oxidation of PET-Derived Monomers Using Excimer Radiation and Hydrogen Peroxide: Kinetic and Operational Insights

by María Gómez, María Claudia Montiel, Elisa Gómez, Asunción María Hidalgo, Fuensanta Máximo and María Dolores Murcia

ChemEngineering 2026, 10(2), 19; https://doi.org/10.3390/chemengineering10020019 - 29 Jan 2026

Viewed by 863

Abstract

Growing environmental concern over plastic pollution has increased the need to address the persistence of PET-derived monomers, such as bis(2-hydroxyethyl) terephthalate (BHET) and terephthalic acid (TPA). This work examines the use of excimer radiation lamps combined with hydrogen peroxide (H₂O₂ [...] Read more.

Growing environmental concern over plastic pollution has increased the need to address the persistence of PET-derived monomers, such as bis(2-hydroxyethyl) terephthalate (BHET) and terephthalic acid (TPA). This work examines the use of excimer radiation lamps combined with hydrogen peroxide (H₂O₂) to enhance advanced oxidation processes (AOPs) for their degradation. This approach stands out for its high selectivity, absence of mercury, and lower production of toxic byproducts. Experimental tests assessed how different operational factors affect pollutant degradation, such as the initial pollutant concentration (50–200 mg/L), the reaction volume (125–500 mL), and the H₂O₂:monomer mass ratio (0:1–6:1 for BHET and 0:1–4:1 for TPA). For BHET, the best results occurred with a 5:1 mass ratio, while TPA degraded optimally with a 3:1 ratio, with a 250 mL reaction volume and a 100 mg/L initial concentration for both compounds. Under these conditions, total degradation of the initial monomers was achieved in around 30 and 80 min for BHET and TPA, respectively, and at the end of the reaction, COD decreased by 46% and 32% relative to their initial values. In both cases, hydrogen peroxide was crucial since UV radiation alone led to much lower degradation efficiency. These results emphasize the need to optimize operational conditions for greater efficiency and establish a starting point for future use of excimer technology in the treatment of wastewater contaminated with PET and its derivatives. Additionally, the degradation data closely matched a pseudo-first-order kinetic model (R² ≈ 1), confirming its reliability for predictive analysis, which is of high importance for the simulation and optimization of the process. Full article

(This article belongs to the Special Issue Advances in Chemical Engineering and Wastewater Treatment)

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13 pages, 661 KB

Open AccessArticle

A Preliminary Investigation into the Influence of Low-Intensity Natural Mid-Infrared and Far-Infrared/Near-Microwave Emissions on the Aroma and Flavor of a Young Dry Red Wine

by Sanghoon Lee, Changgook Lee, Hyunhee Jeong, Sejun Kim, Eok Kyun Lee and Alan J. Buglass

ChemEngineering 2026, 10(2), 18; https://doi.org/10.3390/chemengineering10020018 - 29 Jan 2026

Viewed by 504

Abstract

Brief treatment of a bottled young dry red wine with low-intensity natural emissions in the mid-infrared and far-infrared/near-microwave regions of the electromagnetic spectrum resulted in moderate changes in the concentrations of certain odorants in the wine headspace (vapor), as shown by headspace–solid-phase microextraction–gas [...] Read more.

Brief treatment of a bottled young dry red wine with low-intensity natural emissions in the mid-infrared and far-infrared/near-microwave regions of the electromagnetic spectrum resulted in moderate changes in the concentrations of certain odorants in the wine headspace (vapor), as shown by headspace–solid-phase microextraction–gas chromatography/mass spectrometry (HS-SPME-GC/MS). The headspace levels of certain long-chain ethyl carboxylate esters and methyl salicylate were somewhat enhanced, whereas those of certain aromatic monohydric alcohols, a succinate ester, and oak lactone were somewhat depleted. A tentative explanation of these results is offered whereby waveform treatment results in general re-organization of non-covalent associations of both odorant (volatile) and non-volatile components in wine, leading to the preferential extra release of certain odorants into the headspace (vapor phase) and preferential increased trapping of certain other odorants in wine (liquid phase). Full article

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23 pages, 6146 KB

Open AccessArticle

Intensification of Mixing Processes in Stirred Tanks Using Specific-Power-Matching Double-Stage Configurations of Radially and Axially Pumping Impellers

by Lena Kögel, Achim Gieseking, Carina Zierberg, Mathias Ulbricht and Heyko Jürgen Schultz

ChemEngineering 2026, 10(2), 17; https://doi.org/10.3390/chemengineering10020017 - 26 Jan 2026

Cited by 1 | Viewed by 1354

Abstract

Mixing processes in stirred tanks are widely applied across various industries, but still offer significant potential for optimization. A promising strategy is the use of double-stage impeller setups instead of conventional single impellers. While multi-impeller configurations are common in tall vessels, their benefits [...] Read more.

Mixing processes in stirred tanks are widely applied across various industries, but still offer significant potential for optimization. A promising strategy is the use of double-stage impeller setups instead of conventional single impellers. While multi-impeller configurations are common in tall vessels, their benefits for standard tanks with a height-to-diameter ratio of 1 are largely unexplored. This study systematically investigates the flow fields of single, identical, and mixed double-stage configurations of a Rushton turbine, a pitched-blade turbine, and a retreat curve impeller. To ensure balanced power input in mixed configurations, a refined method for harmonizing specific power via impeller diameter adjustment is proposed. Stereo particle image velocimetry is applied to visualize flow fields, supported by refractive-index matching to enable measurements in a dished-bottom tank. The results reveal substantial flow deficiencies in single-impeller setups. In contrast, double-impeller setups generate novel and significantly improved velocity fields that offer clear advantages and demonstrate strong potential to enhance process efficiency across various mixing applications. These findings provide new experimental insights into the characteristics of dual impellers and form a valuable basis for the design and scale-up of stirred tanks, contributing to more efficient, reliable, and sustainable mixing processes. Full article

(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)

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