Processes

18 pages, 3041 KiB

Open AccessArticle

Atomistic Mechanism of Ion Solution Evaporation: Insights from Molecular Dynamics

by Dayuan Yuan, Liuyang Zhang, Chao Li and Shengqiang Shen

Processes 2025, 13(5), 1369; https://doi.org/10.3390/pr13051369 (registering DOI) - 29 Apr 2025

The study of ion solution evaporation is of paramount importance to the environment as it pertains to numerous critical domains in our lives. This research employs molecular dynamics methods to systematically investigate the influence of ion species, concentration, temperature, and the surface area-to-volume [...] Read more.

The study of ion solution evaporation is of paramount importance to the environment as it pertains to numerous critical domains in our lives. This research employs molecular dynamics methods to systematically investigate the influence of ion species, concentration, temperature, and the surface area-to-volume ratio on the ion solution evaporation process. Firstly, we introduce the process of molecular dynamics modeling of ion solutions, encompassing the selection of simulation parameters, the definition of potential energy functions, and the adjustment of time steps. Subsequently, we analyze the molecular dynamics simulation results from various aspects, such as atomic motion and ion concentration distribution, to elucidate the mechanisms underlying the ion solution evaporation. Finally, we summarize the significance of this study, emphasizing its potential applications in industrial production, water resource management, and ecological preservation, thereby providing a robust theoretical foundation for environmental protection and sustainable development. Full article

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

15 pages, 5490 KiB

Open AccessArticle

Ultra-Low Frequency Oscillation in a Thermal Power System Induced by Doubly-Fed Induction Generators with Inertia Control

by Wei Huang, Suwei Zhai, Xuegang Lu, Xiaojie Zhang, Yanjun Liu, Wei He and Yifan Fang

Processes 2025, 13(5), 1368; https://doi.org/10.3390/pr13051368 (registering DOI) - 29 Apr 2025

Abstract

Ultra-low frequency oscillation has been regarded as a typical instability issue in power systems consisting of hydro turbine synchronous generators due to the water hammer phenomenon. However, the increasing installation of renewable power generators gradually changes the stability mechanisms within multiple frequency bands. [...] Read more.

Ultra-low frequency oscillation has been regarded as a typical instability issue in power systems consisting of hydro turbine synchronous generators due to the water hammer phenomenon. However, the increasing installation of renewable power generators gradually changes the stability mechanisms within multiple frequency bands. In this digest, a new kind of ultra-low frequency oscillation caused by doubly-fed induction generators (DFIGs) equipped with a df/dt controller in a thermal power generation system is introduced. To reveal the underlying mechanism, the motion equation model of the DFIG is constructed, and the simplified analytical model is proposed. The results show that when integrating a df/dt-controlled DFIG into a normal three-machine, nine-bus system, the damping ratio decreases to more than 0.2 when the virtual inertia parameter increases from 5 to 20, leading to a conflict between fast virtual inertial response and stability requirements. Other controllers related to active power regulation are also vital to stability. The frequency domain characteristics of the system are studied to illustrate the influence of key parameters on system stability. Finally, simulation verifications are conducted in MATLAB/Simulink. Full article

(This article belongs to the Special Issue Operation and Control of New Power System with Large-Scale Renewable Energy Integration)

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18 pages, 4823 KiB

Open AccessFeature PaperArticle

Functionalization of Rice Husk for High Selective Extraction of Germanium

by Qunshan Wei, Wei Zeng, Siyi Ding, Zhemin Shen, Xinshan Song, Yuhui Wang, Charles Nzila and Christopher W. K. Chow

Processes 2025, 13(5), 1367; https://doi.org/10.3390/pr13051367 (registering DOI) - 29 Apr 2025

Abstract

It is of strategic significance to extract germanium (Ge) in an ecological way for sustainable development. Adsorbents that already adsorb Ge have disadvantages such as poor selectivity and low adsorption capacity. In this study, a novel adsorbent material based on rice husk functionalized [...] Read more.

It is of strategic significance to extract germanium (Ge) in an ecological way for sustainable development. Adsorbents that already adsorb Ge have disadvantages such as poor selectivity and low adsorption capacity. In this study, a novel adsorbent material based on rice husk functionalized with tannic acid was developed for the efficient extraction of Ge from simulated coal fly ash leachate. The adsorption capacity of tannic acid-functionalized rice husk (TA-EPI-ORH) for Ge was 19.9 times higher than that of untreated rice husk, demonstrating significantly improved performance. The results showed that the adsorption process of Ge by TA-EPI-ORH is consistent with pseudo-second-order kinetic and Freundlich isotherm model. TA-EPI-ORH had excellent selective adsorption properties, with adsorption of 1.40 mg L⁻¹ Ge exceeding 95% and solid-liquid partition coefficients of 4380 mL g⁻¹, even in the presence of nine impurity metal ions (average concentration: 479.08 mg L⁻¹). When compared with the two main coexistence ions—aluminum (Al) and calcium (Ca)—both of which have the relatively highest concentrations (Al: 1594.20 mg L⁻¹, Ca: 1740.13 mg L⁻¹), the separation factors for Ge still maintain relatively high level with SF(Ge/Al) = 42.57 and SF(Ge/Ca) = 39.93. Compared to existing studies, TA-EPI-ORH exhibits superior selective adsorption performance even with the presence of more interfering ions. After elution of the adsorbed Ge from TA-EPI-ORH, the extraction rate of Ge with low initial concentration (1.40 mg L⁻¹) reached 85.17%, while the extraction rates of Al and Ca were only 1.02% and 1.18%, respectively. Further research revealed that the catechol groups on the surface of TA-EPI-ORH formed stable complexes with Ge, whereas the complexes with coexisting ions (e.g., Ca and Al) were unstable, thereby ensuring high selectivity for Ge. This green chemistry-based functionalization of rice husk not only enables high-value utilization of agricultural waste but also provides a sustainable and eco-friendly strategy for efficient Ge separation and recovery. Full article

(This article belongs to the Special Issue Advances in Solid Waste Treatment Technology and Contamination Remediation)

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45 pages, 2738 KiB

Open AccessArticle

Low-Carbon Optimization Operation of Rural Energy System Considering High-Level Water Tower and Diverse Load Characteristics

by Gang Zhang, Jiazhe Liu, Tuo Xie and Kaoshe Zhang

Processes 2025, 13(5), 1366; https://doi.org/10.3390/pr13051366 (registering DOI) - 29 Apr 2025

Abstract

: Against the backdrop of the steady advancement of the national rural revitalization strategy and the dual-carbon goals, the low-carbon transformation of rural energy systems is of critical importance. This study first proposes a comprehensive architecture for rural energy supply systems, incorporating four [...] Read more.

: Against the backdrop of the steady advancement of the national rural revitalization strategy and the dual-carbon goals, the low-carbon transformation of rural energy systems is of critical importance. This study first proposes a comprehensive architecture for rural energy supply systems, incorporating four key dimensions: investment, system configuration, user demand, and policy support. Leveraging the abundant wind, solar, and biomass resources available in rural areas, a low-carbon optimization model for rural energy system operation is developed. The model accounts for diverse load characteristics and the integration of elevated water towers, which serve both energy storage and agricultural functions. The optimization framework targets the multi-energy demands of rural production and daily life—including electricity, heating, cooling, and gas—and incorporates the stochastic nature of wind and solar generation. To address renewable energy uncertainty, the Fisher optimal segmentation method is employed to extract representative scenarios. A representative rural region in China is used as the case study, and the system's performance is evaluated across multiple scenarios using the Gurobi solver. The objective functions include maximizing clean energy benefits and minimizing carbon emissions. Within the system, flexible resources participate in demand response based on their specific response characteristics, thereby enhancing the overall decarbonization level. The energy storage aggregator improves renewable energy utilization and gains economic returns by charging and discharging surplus wind and solar power. The elevated water tower contributes to renewable energy absorption by storing and releasing water, while also supporting irrigation via a drip system. The simulation results demonstrate that the proposed clean energy system and its associated operational strategy significantly enhance the low-carbon performance of rural energy consumption while improving the economic efficiency of the energy system. Full article

(This article belongs to the Section Energy Systems)

19 pages, 6113 KiB

Open AccessArticle

Research on Lightweight Citrus Leaf Pest and Disease Detection Based on PEW-YOLO

by Renzheng Xue and Luqi Wang

Processes 2025, 13(5), 1365; https://doi.org/10.3390/pr13051365 - 29 Apr 2025

Abstract

Timely detection and prevention of citrus leaf diseases and pests are crucial for improving citrus yield. To address the issue of low efficiency in citrus disease and pest detection, this paper proposes a lightweight detection model named PEW-YOLO. First, the PP-LCNet backbone is [...] Read more.

Timely detection and prevention of citrus leaf diseases and pests are crucial for improving citrus yield. To address the issue of low efficiency in citrus disease and pest detection, this paper proposes a lightweight detection model named PEW-YOLO. First, the PP-LCNet backbone is optimized using a novel GSConv convolution, and a lightweight PGNet backbone is introduced to reduce model parameters while enhancing detection performance. Next, the C2f_EMA module, which integrates efficient multi-scale attention (EMA), replaces the original C2f module in the neck, thereby improving feature fusion capabilities. Finally, the Wise-IoU loss function is employed to address the challenge of identifying low-quality samples, further improving both convergence speed and detection accuracy. Experimental results demonstrate that PEW-YOLO achieves a 1.8% increase in mAP50, a 32.2% reduction in parameters, and a detection speed of 1.6 milliseconds per frame on the citrus disease and pest dataset, thereby meeting practical real-time detection requirements. Full article

(This article belongs to the Special Issue Transfer Learning Methods in Equipment Reliability Management)

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18 pages, 14188 KiB

Open AccessArticle

Sustainable Bio-Adsorbent Generated from Coffee Waste for Dual Application in Heavy Metal and Dye Removal

by Jia-Yin Lin, Pei-Tzu Chang, Jun-Ren Shi, Fu-Chen Liu, Chih-Ying Wang and Nai-Wen Tsao

Processes 2025, 13(5), 1364; https://doi.org/10.3390/pr13051364 - 29 Apr 2025

Abstract

Heavy metal and dye contamination from industrial wastewater present substantial dangers to both ecological systems and human well-being. This study explores the upcycling of Coffee Powder Trimmings (CPT), a biomass waste rich in oxygen-containing functional groups, for water remediation. CPT was first used [...] Read more.

Heavy metal and dye contamination from industrial wastewater present substantial dangers to both ecological systems and human well-being. This study explores the upcycling of Coffee Powder Trimmings (CPT), a biomass waste rich in oxygen-containing functional groups, for water remediation. CPT was first used to adsorb Cu²⁺ and Fe³⁺ ions, then pyrolyzed at 750 °C to form metal oxide biochar composites (Cu/CB and Fe/CB). Characterization confirmed the formation of CuO and Fe₃O₄ particles and the retention of key adsorption functionalities. The materials were evaluated for methylene blue (MB) removal across pH levels, various water bodies, and multiple reuse cycles. CPT effectively removed >95% of Cu²⁺ and Fe³⁺ via chelation, while Fe/CB achieved up to 97.8% MB removal due to synergistic π–π, hydrogen bonding, and coordination interactions. Both biochars retained high performance after five cycles, with Fe/CB maintaining 86.88% efficiency. These results highlight CPT-derived biochar as a sustainable, low-cost adsorbent for dual removal of heavy metals and dyes. Full article

(This article belongs to the Special Issue Preparation and Optimization of Carbon Nanomaterials and Composites for Biological and Chemical Applications)

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11 pages, 932 KiB

Open AccessArticle

Piper aduncum Essential Oil: Toxicity to Sitophilus zeamais and Effects on the Quality of Corn Grains

by Weverton Peroni Santos, Lucas Martins Lopes, Gutierres Nelson Silva, Marcela Silva Carvalho and Adalberto Hipólito de Sousa

Processes 2025, 13(5), 1363; https://doi.org/10.3390/pr13051363 - 29 Apr 2025

Abstract

Stored product pests are controlled primarily through applying pyrethroid and organophosphate insecticides or through fumigation with phosphine (PH₃). However, several populations of weevils are resistant to these insecticides. Essential oils appear to be safe alternatives for both humans and the environment. [...] Read more.

Stored product pests are controlled primarily through applying pyrethroid and organophosphate insecticides or through fumigation with phosphine (PH₃). However, several populations of weevils are resistant to these insecticides. Essential oils appear to be safe alternatives for both humans and the environment. The objective was to investigate the toxicity of Piper aduncum essential oil (PAEO) to Sitophilus zeamais and evaluate its effects on corn grain quality during the four-month storage period. This study was conducted in two stages. In the first stage, the toxicity of PAEO at concentrations lethal to 50 and 95% of insects (LC₅₀ and LC₉₅) was estimated. The second step evaluated the degree of infestation, water content, apparent specific mass, loss of mass, electrical conductivity, and percentage of germination of grains at 0, 30, 60, 90, and 120 days after exposure to PAEO, deltamethrin (pyrethroid), and the control treatment. PAEO presents toxicity to S. zeamais. The LC₅₀ and LC₉₅ values are 298.50 µL kg⁻¹ and 585.20 µL kg⁻¹, respectively. The increases in infestation degree, water content, electric conductivity, and mass loss, as well as reductions in apparent specific mass and germination, show the loss of corn quality during the 120-day storage period, being more significant when no product is applied. PAEO delays the loss of quality of the grains, presenting a greater capacity to preserve the grains for a longer period. Full article

(This article belongs to the Special Issue Advances in the Composition and Extraction Process of Natural Extracts to Insects and Microorganisms Management)

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21 pages, 5508 KiB

Open AccessArticle

Research on the Adsorption Characteristics of Shale Gas in Different Types of Kerogen

by Ao Yin, Zhixiang Liu, Yongli Zhang and Yulin Ma

Processes 2025, 13(5), 1362; https://doi.org/10.3390/pr13051362 - 29 Apr 2025

Abstract

To investigate the methane adsorption characteristics in different types of kerogen, microscopic models for three kerogen types—sapropelic (Type I), mixed (Type II), and humic (Type III)—were developed in this paper based on the paradigm diagram. Using Materials Studio 2020 software, a combination of [...] Read more.

To investigate the methane adsorption characteristics in different types of kerogen, microscopic models for three kerogen types—sapropelic (Type I), mixed (Type II), and humic (Type III)—were developed in this paper based on the paradigm diagram. Using Materials Studio 2020 software, a combination of molecular dynamics and Monte Carlo adsorption simulations was employed to examine the kerogen from the molecular structure to the cellular structure, with an analysis rooted in thermodynamic theory. The results indicated that the elemental composition of kerogen significantly influenced both the heat of adsorption and the adsorption position, with sulfur (S) having the greatest effect. Specifically, the C-S bond shifted the methane adsorption position horizontally by 0.861 Å and increased the adsorption energy by 1.418 kJ. Among the three types of kerogen crystals, a relationship was observed among the adsorption amount, limiting adsorption energy, and specific adsorption energy, with Type I < Type II < Type III. Additionally, the limiting adsorption energy was greater than the specific adsorption energy. The limiting adsorption energy of Type Ⅲ was only 28.436 kJ/mol, which indicates that methane is physically adsorbed in the kerogen. Regarding the diffusion coefficient, the value of 0.0464 Å²/Ps in the micropores of Type I kerogen was significantly higher than that in Types II and III, though it was much smaller than the diffusion coefficient observed in the macropores. Additionally, adsorption causes volumetric and effective pore volume expansion in kerogen crystals, which occurs in two phases: slow expansion and rapid expansion. Higher types of kerogen require a larger adsorption volume to reach the rapid expansion phase and expand more quickly. However, during the early stage of adsorption, the expansion rate is extremely low, and even a slight shrinkage may occur. Therefore, in shale gas extraction, it is crucial to design the extraction strategy based on the content and adsorption characteristics of the three kerogen types in order to enhance shale gas production and improve extraction efficiency. Full article

(This article belongs to the Special Issue Advanced Reservoir Simulation and Modelling in Oil and Gas-Related Processes)

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22 pages, 9537 KiB

Open AccessArticle

Study on Wellbore Stability of Shale–Sandstone Interbedded Shale Oil Reservoirs in the Chang 7 Member of the Ordos Basin

by Yu Suo, Xuanwen Kong, Heng Lyu, Cuilong Kong, Guiquan Wang, Xiaoguang Wang and Lingzhi Zhou

Processes 2025, 13(5), 1361; https://doi.org/10.3390/pr13051361 - 29 Apr 2025

Abstract

Wellbore instability is a major constraint in large-scale shale oil extraction. This study focuses on the shale–sandstone interbedded shale oil reservoirs in the Chang 7 area, delving into the evolutionary principles governing wellbore stability in horizontal drilling operations within these formations. A geological [...] Read more.

Wellbore instability is a major constraint in large-scale shale oil extraction. This study focuses on the shale–sandstone interbedded shale oil reservoirs in the Chang 7 area, delving into the evolutionary principles governing wellbore stability in horizontal drilling operations within these formations. A geological feature analysis of shale–sandstone reservoir characteristics coupled with rigorous mechanical experimentation was undertaken to investigate the micro-mechanisms underpinning wellbore instability. The Mohr–Coulomb failure criterion applicable to sandstone and the multi-weakness planes failure criterion of shale were integrated to analyze the stress distribution of surrounding rocks within horizontal wells, facilitating the computation of collapse pressure and fracture pressure. A finite element model of wellbore stability in shale–sandstone horizontal drilling was established, and then we conducted a comprehensive analysis of the impacts of varying elastic moduli, Poisson’s ratio, and in-situ stress on wellbore stability. The findings reveal that under varying confining pressures, the predominant failure mode observed in most sandstone samples is characterized by inclined shear failure, coupled with a reduced incidence of crack formation. The strength of shale escalates proportionally with increasing confining pressure, resulting in a reduced susceptibility to failure along its inherent weak planes. This transition is characterized by a gradual shift from the prevalent mode of longitudinal splitting towards inclined shear failure. As the elastic modulus of shale rises, the discrepancy between circumferential and radial stresses decreases. In contrast, with the increasing elastic modulus of sandstone, the gap between circumferential and radial stresses widens, potentially inducing potential instabilities in the wellbore. An increase in sandstone’s Poisson’s ratio corresponds to a proportional increase in the difference between circumferential and radial stresses. Under reverse fault stress regimes, wellbore collapse and instability are predisposed to occur. Calculations of collapse pressure and fracture pressure reveal that the safety density window is minimized at the interface between shale and sandstone, rendering it susceptible to wellbore instability. These research findings offer significant insights for the investigation of wellbore stability in interbedded shale–sandstone reservoirs contributing to the academic discourse in this field. Full article

(This article belongs to the Special Issue Advanced Research on Marine and Deep Oil & Gas Development)

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19 pages, 6105 KiB

Open AccessArticle

Polylactic Acid and Polyhydroxybutyrate as Printed Circuit Board Substrates: A Novel Approach

by Zahra Fazlali, David Schaubroeck, Maarten Cauwe, Ludwig Cardon, Pieter Bauwens and Jan Vanfleteren

Processes 2025, 13(5), 1360; https://doi.org/10.3390/pr13051360 - 29 Apr 2025

Abstract

This study presents a novel approach to manufacture a rigid printed circuit board (PCB) using sustainable polymers. Current PCBs use a fossil-fuel-based substrate, like FR4. This presents recycling challenges due to its composite nature. Replacing the substrate with an environmentally friendly alternative leads [...] Read more.

This study presents a novel approach to manufacture a rigid printed circuit board (PCB) using sustainable polymers. Current PCBs use a fossil-fuel-based substrate, like FR4. This presents recycling challenges due to its composite nature. Replacing the substrate with an environmentally friendly alternative leads to a reduction in negative impacts. Polylactic acid (PLA) and Polyhydroxybutyrate (PHB) biopolymers are used in this study. These two biopolymers have low melting points (130–180 °C, and 170–180 °C, respectively) and cannot withstand the high temperature soldering process (up to 260 °C for standard SAC (SnAgCu, tin/silver/copper) lead free solder processes). Our approach for replacing the PCB substrate is applying the PLA/PHB carrier substrate at the end of the PCB manufacturing process using injection molding technology. This approach involves all the standard PCB processes, including wet etching of the Cu conductors, and component assembly with SAC solder on a thin flexible polyimide (PI) foil with patterned Cu conductors and then overmolding the biopolymer onto the foil to create a rigid base. This study demonstrates the functionality of two test circuits fabricated using this method. In addition, we evaluated the adhesion between the biopolymer and PI to achieve a durable PCB. Moreover, we performed two different end-of-life approaches (debonding and composting) as a part of the end-of-life consideration. By incorporating biodegradable materials into PCB standard manufacturing, the CO₂ emissions and energy consumption are significantly reduced, and installation costs are lowered. Full article

(This article belongs to the Special Issue Innovations in Manufacturing Processes and Systems for Sustainable Practices)

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22 pages, 3674 KiB

Open AccessArticle

A Dual-Loop Modified Active Disturbance Rejection Control Scheme for a High-Purity Distillation Column

by Xudong Song, Yuedong Zhao, Zihao Li, Jingchao Song, Zhenlong Wu, Jingzhong Guo and Jian Zhang

Processes 2025, 13(5), 1359; https://doi.org/10.3390/pr13051359 - 29 Apr 2025

Abstract

High-purity distillation columns typically give rise to multi-variable, strongly coupled nonlinear systems with substantial time delay and significant inertia. The control performance of high-purity distillation columns crucially influences the purity of the final product. Taking into account the process of a high-purity distillation [...] Read more.

High-purity distillation columns typically give rise to multi-variable, strongly coupled nonlinear systems with substantial time delay and significant inertia. The control performance of high-purity distillation columns crucially influences the purity of the final product. Taking into account the process of a high-purity distillation column, this article puts forward a dual-loop modified active disturbance rejection control (MADRC) scheme to improve the control of product purity. During the stable operation of the distillation process, the structures of two control loops are, respectively, approximated by two linear transfer function models via open-loop experiments. Subsequently, the compensation part of the MADRC scheme is designed, respectively, for each approximate model. Furthermore, this paper employs singular perturbation theory to prove the stability of MADRC. The performance of the dual-loop MADRC scheme (MADRC) is compared with that of a proportional–integral–derivative (PID) control scheme, a cascade PID control scheme (CPID), and a regular ADRC scheme (ADRC). The simulations demonstrate that the dual-loop MADRC scheme is capable of efficiently tracking the reference value and exhibits optimal disturbance rejection capabilities. Additionally, the superiority of the dual-loop MADRC scheme is validated through Monte Carlo trials. Full article

(This article belongs to the Special Issue Modeling, Simulation and Control of Industrial Processes)

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18 pages, 2561 KiB

Open AccessArticle

Pyrolyzed Biochar from Agricultural Byproducts: Synthesis, Characterization, and Application in Water Pollutants Removal

by Niloy Chandra Sarker, Md Abdur Rahim Badsha, Greta Hillukka, Bethany Holter, Michael Kjelland and Khwaja Hossain

Processes 2025, 13(5), 1358; https://doi.org/10.3390/pr13051358 - 29 Apr 2025

Abstract

Biochar is a carbon-rich, porous substance produced from the thermal degradation process of carbon-based materials, like biomass and other solid waste, in an oxygen-deprived environment. The type of parent material and the conditions for processing are the principal factors in determining the properties [...] Read more.

Biochar is a carbon-rich, porous substance produced from the thermal degradation process of carbon-based materials, like biomass and other solid waste, in an oxygen-deprived environment. The type of parent material and the conditions for processing are the principal factors in determining the properties of biochar. Because of its diverse physicochemical properties, biochar has gained growing attention over the decades as a cost-effective, sustainable, and emerging material with potential applications in energy, agriculture, and environmental sectors like wastewater treatment. Two different parent materials, such as wheat bran and maple leaf, were pyrolyzed at three different temperatures (300 °C, 500 °C, and 700 °C). The resultant biochar was analyzed for its adsorptive potential for different contaminants. All the tested physicochemical property values of the maple (Acer) leaf biochar were found to be higher than wheat (Triticum) bran biochar except bulk density and the dye absorption potential. Based on the biochar physiochemical properties, the pyrolysis temperature of 700 °C was found to be the best for pyrolyzing these biomasses. Irrespective of the biochar types, pH 2.0 with a residence time of 90 min outperformed with an initial dye concentration of 0.05 mg/mL and a biochar application rate of 50 mg/mL. Furthermore, MLBC exhibited higher oil adsorption potential in comparison with that of WBC. The addition of WBC and MLBC to the polymer beads increases their dye absorption competence; therefore, this biochar can be a potential means of water treatment. Full article

(This article belongs to the Special Issue Progress in Biorefinery of Lignocellulosic Biomass to Bio-Energies and Bio-Based Chemicals)

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24 pages, 3124 KiB

Open AccessArticle

Trends in Polychlorinated Biphenyl Contamination in Bucharest’s Urban Soils: A Two-Decade Perspective (2002–2022)

by Mirela Alina Sandu, Mihaela Preda, Veronica Tanase, Denis Mihailescu, Ana Virsta and Veronica Ivanescu

Processes 2025, 13(5), 1357; https://doi.org/10.3390/pr13051357 - 29 Apr 2025

Abstract

Polychlorinated biphenyls (PCBs) are synthetic organic compounds that were widely used in industrial applications throughout the 20th century. Due to their chemical stability, resistance to degradation and ability to bioaccumulate and biomagnify through food chains, PCBs pose long-term environmental and health risks. Due [...] Read more.

Polychlorinated biphenyls (PCBs) are synthetic organic compounds that were widely used in industrial applications throughout the 20th century. Due to their chemical stability, resistance to degradation and ability to bioaccumulate and biomagnify through food chains, PCBs pose long-term environmental and health risks. Due to these characteristics, PCBs have been globally regulated as persistent organic pollutants (POPs), despite being banned from production in most countries decades ago. This study investigates temporal trends in PCB contamination in urban soils of Bucharest over a 20-year period (2002–2022), focusing on six principal congeners (PCB 28, 52, 101, 138, 153, and 180) sampled from 13 locations, including roadsides and urban parks. Gas chromatography and spatial analysis using inverse distance weighting (IDW) revealed a marked reduction in Σ6PCB concentrations, declining from 0.0159 mg/kg in 2002 to 0.0065 mg/kg in 2022, with statistically significant differences confirmed by Kruskal–Wallis analysis (p < 0.05). This decline is primarily attributed to reduced emissions, source control measures, and natural attenuation. However, the persistence of PCBs in localized hotspots is influenced by secondary dispersion mechanisms, such as atmospheric deposition and surface runoff, which redistribute contaminants rather than eliminate them. Health risk assessments via ingestion, dermal absorption, and inhalation routes confirmed negligible carcinogenic risk for both adults and children. Although measurable progress has been achieved, the persistence of localized contamination underscores the need for targeted remediation strategies and sustained environmental monitoring to protect vulnerable urban areas from recontamination. Full article

(This article belongs to the Special Issue 1st SUSTENS Meeting: Advances in Sustainable Engineering Systems)

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24 pages, 2442 KiB

Open AccessArticle

Monte Carlo Sensitivity Analysis for a Carbon Capture, Utilization, and Storage Whole-Process System

by Zhuo Han, Hang Liu, Dongya Zhao, Yurong Chen, Yupeng Xing and Zixuan Zhang

Processes 2025, 13(5), 1356; https://doi.org/10.3390/pr13051356 - 29 Apr 2025

Abstract

Carbon capture, utilization, and storage (CCUS) is an emerging technology with significant potential for large-scale emissions reduction. To reduce the overall system costs of CCUS, this study first establishes a comprehensive economic cost model for the entire CCUS process. Subsequently, a Monte Carlo-based [...] Read more.

Carbon capture, utilization, and storage (CCUS) is an emerging technology with significant potential for large-scale emissions reduction. To reduce the overall system costs of CCUS, this study first establishes a comprehensive economic cost model for the entire CCUS process. Subsequently, a Monte Carlo-based Sobol’ global sensitivity analysis method is proposed to calculate both first-order and total-order sensitivity indices, followed by qualitative and quantitative analyses of parameter sensitivity. Additionally, convergence analyses of the results and their engineering applicability are examined. The findings reveal that the total-order sensitivity indices for electricity price, flue gas inlet flow rate, pipeline diameter, pipeline material price, pipeline inlet pressure, and injection pressure are 0.6578, 0.3857, 0.5585, 0.3823, 0.2205, and 0.1949, respectively, which are significantly higher than those of the other parameters. This indicates that these parameters have a dominant impact on energy consumption costs through the processes of capture and compression, pipeline transportation, and storage injection. These results provide a basis for selecting decision variables when optimizing the entire CCUS process. Full article

(This article belongs to the Special Issue Carbon Capture, Transportation, Utilization and Storage (CCUS) Process Optimization (CCUSPO))

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16 pages, 30990 KiB

Open AccessArticle

Reservoir Characterization of Tight Sandstone Gas Reservoirs: A Case Study from the He 8 Member of the Shihezi Formation, Tianhuan Depression, Ordos Basin

by Zihao Dong, Xinzhi Yan, Jingong Zhang, Zhiqiang Chen and Hongxing Ma

Processes 2025, 13(5), 1355; https://doi.org/10.3390/pr13051355 - 29 Apr 2025

Abstract

Tight sandstone gas reservoirs, characterized by low porosity (typically < 10%) and ultra-low permeability (commonly < 0.1 × 10⁻³ μm²), represent a critical transitional resource in global energy transition, accounting for over 60% of total natural gas production in regions [...] Read more.

Tight sandstone gas reservoirs, characterized by low porosity (typically < 10%) and ultra-low permeability (commonly < 0.1 × 10⁻³ μm²), represent a critical transitional resource in global energy transition, accounting for over 60% of total natural gas production in regions such as North America and Canada. In the northern Tianhuan Depression of the Ordos Basin, the Permian He 8 Member (He is the abbreviation of Shihezi) of the Shihezi Formation serves as one of the primary gas-bearing intervals within such reservoirs. Dominated by quartz sandstones (82%) with subordinate lithic quartz sandstones (15%), these reservoirs exhibit pore systems primarily supported by high-purity quartz and rigid lithic fragments. Diagenetic processes reveal sequential cementation: early-stage quartz cementation provides a framework for subsequent lithic fragment cementation, collectively resisting compaction. Depositionally, these sandstones are associated with fluvial-channel environments, evidenced by a sand-to-mud ratio of ~5.2:1. Pore structures are dominated by intergranular pores (65%), followed by dissolution pores (25%) formed via selective leaching of unstable minerals by acidic fluids in hydrothermal settings, and minor intragranular pores (10%). Authigenic clay minerals, predominantly kaolinite (>70% of total clays), act as the main interstitial material. Reservoir properties average 7.01% porosity and 0.5 × 10⁻³ μm² permeability, defining a typical low-porosity, ultra-low-permeability system. Vertically stacked sand bodies in the He 8 Member display large single-layer thicknesses (5–12 m) and moderate sealing capacity (caprock breakthrough pressure > 8 MPa), hosting gas–water mixed-phase occurrences. Rock mechanics experiments demonstrate that fractures enhance permeability by >60%, significantly controlling reservoir heterogeneity. Full article

(This article belongs to the Special Issue Advanced Studies of Oil and Gas Flow in Unconventional Oil and Gas Reservoir)

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22 pages, 5180 KiB

Open AccessReview

Research Progress of Nonthermal Plasma for Ammonia Synthesis

by Xiaowang Yan, Dengyun Wang, Lijian Wang, Dingkun Yuan, Zhongqian Ling, Xinlu Han and Xianyang Zeng

Processes 2025, 13(5), 1354; https://doi.org/10.3390/pr13051354 - 28 Apr 2025

Abstract

Ammonia (NH₃) plays a vital role in both the agriculture and energy sectors, serving as a precursor for nitrogen fertilizers and as a promising carbon-free fuel and hydrogen carrier. However, the conventional Haber–Bosch process is highly energy-intensive, operating under elevated temperatures [...] Read more.

Ammonia (NH₃) plays a vital role in both the agriculture and energy sectors, serving as a precursor for nitrogen fertilizers and as a promising carbon-free fuel and hydrogen carrier. However, the conventional Haber–Bosch process is highly energy-intensive, operating under elevated temperatures and pressures, and contributes significantly to global CO₂ emissions. In recent years, nonthermal plasma (NTP)-assisted ammonia synthesis has emerged as a promising alternative that enables ammonia production under mild conditions. With its ability to activate inert N₂ molecules through energetic electrons and reactive species, NTP offers a sustainable route with potential integration into renewable energy systems. This review systematically summarizes recent advances in NTP-assisted ammonia synthesis, covering reactor design, catalyst development, plasma–catalyst synergistic mechanisms, and representative reaction pathways. Particular attention is given to the influence of key plasma parameters, such as discharge power, pulse voltage, frequency, gas flow rate, and N₂/H₂ ratio, on reaction performance and energy efficiency. Additionally, comparative studies on plasma reactor configurations and materials are presented. The integration of NTP systems with green hydrogen sources and strategies to mitigate ammonia decomposition are also discussed. This review provides comprehensive insights and guidance for advancing efficient, low-carbon, and distributed ammonia production technologies. Full article

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

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13 pages, 1158 KiB

Open AccessArticle

High-Pressure- and High-Temperature-Resistant Resins as Leakage Control Materials in Drilling Fluids

by Chunsheng Wang, Zhen Zhang, Tao Wang, Keming Fu and Gang Xie

Processes 2025, 13(5), 1353; https://doi.org/10.3390/pr13051353 - 28 Apr 2025

Viewed by 46

Abstract

Well leakage is a recurring hazard in drilling operations that can lead to significant loss of drilling fluids and serious consequences when drilling fluids seep into the formation. Increasing drilling depths correspond to elevated formation temperatures and pressures, which place stringent demands on [...] Read more.

Well leakage is a recurring hazard in drilling operations that can lead to significant loss of drilling fluids and serious consequences when drilling fluids seep into the formation. Increasing drilling depths correspond to elevated formation temperatures and pressures, which place stringent demands on leakage control materials. In this study, a high-pressure- and high-temperature-resistant branched resin, poly-BDEB, was synthesized using 2,2-bis(4-hydroxyphenyl)propane diepoxyglycidyl ether and epoxy crack adhesive B. The properties of the branched resin poly-BDEB were characterized. Leakage control performance of the branched resin poly-BDEB was evaluated through single-stage and multi-stage crack plugging experiments to determine its effectiveness. The results show that poly-BDEB maintains structural stability under pressures of up to 198.33 MPa. Poly-BDEB has a stable structure and will not be thermally decomposed at 352.25 °C. These properties demonstrate poly-BDEB’s excellent pressure and temperature resistance. The density of branched resin poly-BDEB is 1.07 g/cm³. When its concentration in the drilling fluid reaches 24% (8%A + 8%B + 8%C), it still maintains good sedimentation stability. Poly-BDEB can effectively plug single-stage and multi-stage fractures ranging from 1 to 3 mm in width. Unlike conventional leakage circulation materials (LCMs), poly-BDEB features a branched molecular structure that improves its mechanical strength, thermal stability, and bridging efficiency in fractures. This study can provide technical support for leakage control in deep and ultra-deep wells during drilling. Full article

(This article belongs to the Section Materials Processes)

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16 pages, 2497 KiB

Open AccessArticle

Bayesian Deep Reinforcement Learning for Operational Optimization of a Fluid Catalytic Cracking Unit

by Jingsheng Qin, Lingjian Ye, Jiaqing Zheng and Jiangnan Jin

Processes 2025, 13(5), 1352; https://doi.org/10.3390/pr13051352 - 28 Apr 2025

Viewed by 38

Abstract

The emerging machine learning techniques provide great opportunities for optimal operation of chemical systems. This paper presents a Bayesian deep reinforcement learning method for the optimization of a fluid catalytic cracking (FCC) unit, which is a key process in the petroleum refining industry. [...] Read more.

The emerging machine learning techniques provide great opportunities for optimal operation of chemical systems. This paper presents a Bayesian deep reinforcement learning method for the optimization of a fluid catalytic cracking (FCC) unit, which is a key process in the petroleum refining industry. Unlike the traditional reinforcement learning (RL) methods that use deterministic network weights, Bayesian neural networks are incorporated to represent the RL agent. The Bayesian treatment is integrated with the primal-dual method to handle the process constraints. Simulated experiments for FCC determined that the proposed algorithm achieves more stable control performance and higher economic profits, especially under parameter fluctuations and external disturbances. Full article

(This article belongs to the Special Issue Machine Learning Optimization of Chemical Processes)

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24 pages, 2460 KiB

Open AccessArticle

Catalytic Cracking of Non-Hydrotreated, Hydrotreated and Sulfuric Acid-Treated Vacuum Gas Oils

by Dicho Stratiev

Processes 2025, 13(5), 1351; https://doi.org/10.3390/pr13051351 - 28 Apr 2025

Viewed by 47

Abstract

The quality of the catalytic cracking feed can affect the conversion by 35%, while the activity of the catalyst can influence the conversion by 11% and the reaction temperature by 15%. The pivotal role of feed quality justifies the investigations directed to better [...] Read more.

The quality of the catalytic cracking feed can affect the conversion by 35%, while the activity of the catalyst can influence the conversion by 11% and the reaction temperature by 15%. The pivotal role of feed quality justifies the investigations directed to better understanding which components of the feed impinge the conversion, yields, selectivity and properties of the catalytic cracking products. In this research, two virgin vacuum gas oils, a hydrotreated vacuum gas oil and five sulfuric acid-treated vacuum gas oils were cracked on a commercial equilibrium catalyst (Nova DAO) in a micro-activity (MAT) unit at different catalyst-to-oil ratios to obtain the conversion, yields, and selectivities at the point of maximum gasoline yield. The treatment of one of the virgin and the hydrotreated vacuum gas oils with sulfuric acid decreased the heavy aromatics from 22.6 to 0.0 wt.% and resins from 2.7 to 0.0 wt.%. Intercriteria analysis of the experimental cracking data revealed that the reduction and removal of the heavy aromatic compounds from the vacuum gas oil had a profound effect on conversion, yields, and gasoline quality. It led to conversion enhancement from 70.8 to 86.1 wt.% and a reduction of gasoline research octane number by two points. The conversion at the maximum gasoline yield was confirmed to be very well predicted by a correlation that includes the empirical parameters aromatic carbon and hydrogen contents with %AAD of 0.7 wt.% and maximum absolute deviation of 2.3 wt.%. Full article

(This article belongs to the Special Issue Petroleum Characterization and Bioprocesses: Numerical and Experimental Investigation (2nd Edition))

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36 pages, 3070 KiB

Open AccessArticle

Optimized Coordination of Distributed Energy Resources in Modern Distribution Networks Using a Hybrid Metaheuristic Approach

by Mohammed Alqahtani and Ali S. Alghamdi

Processes 2025, 13(5), 1350; https://doi.org/10.3390/pr13051350 - 28 Apr 2025

Viewed by 42

Abstract

This paper presents a comprehensive optimization framework for modern distribution systems, integrating distribution system reconfiguration (DSR), soft open point (SOP) operation, photovoltaic (PV) allocation, and energy storage system (ESS) management to minimize daily active power losses. The proposed approach employs a novel hybrid [...] Read more.

This paper presents a comprehensive optimization framework for modern distribution systems, integrating distribution system reconfiguration (DSR), soft open point (SOP) operation, photovoltaic (PV) allocation, and energy storage system (ESS) management to minimize daily active power losses. The proposed approach employs a novel hybrid metaheuristic algorithm, the Cheetah-Grey Wolf Optimizer (CGWO), which synergizes the global exploration capabilities of the Cheetah Optimizer (CO) with the local exploitation strengths of Grey Wolf Optimization (GWO). The optimization model addresses time-varying loads, renewable generation profiles, and dynamic network topology while rigorously enforcing operational constraints, including radiality, voltage limits, ESS state-of-charge dynamics, and SOP capacity. Simulations on a 33-bus distribution system demonstrate the effectiveness of the framework across eight case studies, with the full DER integration case (DSR + PV + ESS + SOP) achieving a 67.2% reduction in energy losses compared to the base configuration. By combining the global exploration of CO with the local exploitation of GWO, the hybrid CGWO algorithm outperforms traditional techniques (such as PSO and GWO) and avoids premature convergence while preserving computational efficiency—two major drawbacks of standalone metaheuristics. Comparative analysis highlights CGWO’s superiority over standalone algorithms, yielding the lowest energy losses (997.41 kWh), balanced ESS utilization, and stable voltage profiles. The results underscore the transformative potential of coordinated DER optimization in enhancing grid efficiency and reliability. Full article

(This article belongs to the Special Issue Recent Advances in Renewable Energy Systems: Integration Challenges, Forecasting, and Grid Optimization for Sustainable Energy Management)

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42 pages, 4293 KiB

Open AccessArticle

Optimizing Hydrogen Liquefaction Efficiency Through Waste Heat Recovery: A Comparative Study of Three Process Configurations

by Seyed Masoud Banijamali, Adrian Ilinca, Ali Alizadeh Afrouzi and Daniel R. Rousse

Processes 2025, 13(5), 1349; https://doi.org/10.3390/pr13051349 - 28 Apr 2025

Viewed by 38

Abstract

Hydrogen (H₂) liquefaction is an energy-intensive process, and improving its efficiency is critical for large-scale deployment in H₂ infrastructure. Industrial waste heat recovery contributes to energy savings and environmental improvements in liquid H₂ processes. This study proposes a comparative [...] Read more.

Hydrogen (H₂) liquefaction is an energy-intensive process, and improving its efficiency is critical for large-scale deployment in H₂ infrastructure. Industrial waste heat recovery contributes to energy savings and environmental improvements in liquid H₂ processes. This study proposes a comparative framework for industrial waste heat recovery in H₂ liquefaction systems by examining three recovery cycles, including an ammonia–water absorption refrigeration (ABR) unit, a diffusion absorption refrigeration (DAR) process, and a combined organic Rankine/Kalina plant. All scenarios incorporate 2 MW of industrial waste heat to improve precooling and reduce the external power demand. The simulations were conducted using Aspen HYSYS (V10) in combination with an m-file code in MATLAB (R2022b) programming to model each configuration under consistent operating conditions. Detailed energy and exergy analyses are performed to assess performance. Among the three scenarios, the ORC/Kalina-based system achieves the lowest specific power consumption (4.306 kWh/kg LH₂) and the highest exergy efficiency in the precooling unit (70.84%), making it the most energy-efficient solution. Although the DAR-based system shows slightly lower performance, the ABR-based system achieves the highest exergy efficiency of 52.47%, despite its reduced energy efficiency. By comparing three innovative configurations using the same industrial waste heat input, this work provides a valuable tool for selecting the most suitable design based on either energy performance or thermodynamic efficiency. The proposed methodology can serve as a foundation for future system optimization and scale-up. Full article

(This article belongs to the Special Issue Insights into Hydrogen Production Using Solar Energy)

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30 pages, 3681 KiB

Open AccessReview

Recent Trends in the Use of Electrode Materials for Microbial Fuel Cells Accentuating the Potential of Photosynthetic Cyanobacteria and Microalgae: A Review

by Ponnusamy Ramesh, Rishika Gupta, Chelliah Koventhan, Gangatharan Muralitharan, An-Ya Lo, Yi-Jen Huang and Saravanan Ramasamy

Processes 2025, 13(5), 1348; https://doi.org/10.3390/pr13051348 - 28 Apr 2025

Viewed by 51

Abstract

As of 2024, approximately 81.5% of global energy consumption is still derived from non-renewable fossil fuels, such as coal, oil, and natural gas. This highlights the urgent need to transition to alternative energy sources amid the escalating climate crisis. Cyanobacteria and microalgae have [...] Read more.

As of 2024, approximately 81.5% of global energy consumption is still derived from non-renewable fossil fuels, such as coal, oil, and natural gas. This highlights the urgent need to transition to alternative energy sources amid the escalating climate crisis. Cyanobacteria and microalgae have emerged as promising biocatalysts in microbial fuel cells (MFCs) for eco-friendly energy production, owing to their photosynthetic abilities and resilience in regard to various environmental conditions. This review explores the potential of cyanobacteria and microalgae to drive bioelectricity generation via metabolic and extracellular electron transfer processes, leveraging their ability to fix carbon and nitrogen, while thriving in challenging environments. Bioengineering and electrode design advances are integrated to enhance the electron transfer efficacy and constancy of cyanobacteria-based MFCs. This approach addresses the growing demand for carbon-neutral energy and can be applied to wastewater treatment and bioremediation scenarios. By synergizing biological innovation with sustainable engineering techniques, this review establishes cyanobacteria and microalgal-driven MFCs as a scalable and eco-friendly platform for next-generation energy systems. The findings lay the groundwork for further exploration of the role of cyanobacteria and microalgae in bridging the gap between renewable energy production and environmental stewardship. Full article

(This article belongs to the Special Issue Electrode Materials Design for High-Performance Energy Conversion and Storage Devices)

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12 pages, 4173 KiB

Open AccessArticle

A Permittivity Measurement Sensor Based on Ridge Substrate-Integrated Waveguide

by Hu Chen, Han Yan, Mingyi Gou, Kewen Hu and Ji Liu

Processes 2025, 13(5), 1347; https://doi.org/10.3390/pr13051347 - 28 Apr 2025

Viewed by 65

Abstract

In this paper, a novel ridge substrate-integrated waveguide (RSIW) sensor is proposed, and the RSIW is optimized and simulated using full-wave simulation. A RSIW-based system was developed for measuring the permittivity of substances, and a neural network algorithm was utilized to reconstruct the [...] Read more.

In this paper, a novel ridge substrate-integrated waveguide (RSIW) sensor is proposed, and the RSIW is optimized and simulated using full-wave simulation. A RSIW-based system was developed for measuring the permittivity of substances, and a neural network algorithm was utilized to reconstruct the permittivity in real time. The system was employed to measure the permittivity of mixed solutions of ethanol and deionized water, and the results were consistent with those obtained using a Keysight commercial probe. The relative errors of the real part and loss tangent were found to be less than 3% and 5%, respectively. These results indicate that the RSIW measuring apparatus is capable of accurate real-time measurement of the permittivity of materials. The simplicity of the manufacturing process, the reduced quantity of measurement samples, and the ease with which they can be prepared all contribute to the potential for microwave energy and microwave wastewater detection application. Full article

(This article belongs to the Special Issue Microwave Applications in Chemistry and Industry)

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17 pages, 5850 KiB

Open AccessArticle

Pore Structure Characterization of Low-Permeability Gravity-Flow Reservoirs: A Case Study of the Middle Es3 Member in Daluhu Area, the Dongying Depression, China

by Yifan Zhang, Shaochun Yang, Yong Wang, Shilong Ma and Dongmou Huang

Processes 2025, 13(5), 1346; https://doi.org/10.3390/pr13051346 - 28 Apr 2025

Viewed by 55

Abstract

The low-permeability gravity-flow sandstone reservoirs in the Dongying Depression, China, contain substantial oil reserves, yet their development is constrained by complex pore structures. In this study, optical and scanning electron microscopy (SEM) observations were integrated with nuclear magnetic resonance (NMR) measurements to investigate [...] Read more.

The low-permeability gravity-flow sandstone reservoirs in the Dongying Depression, China, contain substantial oil reserves, yet their development is constrained by complex pore structures. In this study, optical and scanning electron microscopy (SEM) observations were integrated with nuclear magnetic resonance (NMR) measurements to investigate the pore system, pore size distribution, and connectivity of Es3z sandstone. By applying a Gaussian multi-peak fitting algorithm to the NMR T₂ spectra, parameters that directly capture the physical attributes of the rocks were extracted. Based on the correlation between these parameters and permeability, three distinct pore structure types (A, B, and C) were identified. The results demonstrate the effectiveness of using these NMR T₂ spectral parameters for quantitative pore structure characterization and classification, providing a robust framework for evaluating and predicting the quality of low-permeability reservoirs. Full article

(This article belongs to the Section Energy Systems)

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26 pages, 4188 KiB

Open AccessFeature PaperArticle

Valorization of Residual Biomass from Sargassum filipendula for the Extraction of Phlorotannins and Pigments Using Eutectic Solvents

by Pedro Afonso Vasconcelos Paes Mello, Cristiane Nunes da Silva and Bernardo Dias Ribeiro

Processes 2025, 13(5), 1345; https://doi.org/10.3390/pr13051345 - 28 Apr 2025

Viewed by 68

Abstract

Sargassum filipendula is a marine macroalgae, also known as brown algae. These species contain significant amounts of polysaccharides, such as alginates, and phenolic compounds, including phlorotannins, with excellent biological properties. This study evaluated the extraction of bioactive compounds from the residual biomass of [...] Read more.

Sargassum filipendula is a marine macroalgae, also known as brown algae. These species contain significant amounts of polysaccharides, such as alginates, and phenolic compounds, including phlorotannins, with excellent biological properties. This study evaluated the extraction of bioactive compounds from the residual biomass of Sargassum filipendula using deep eutectic solvents based on alkanol amines combined with polyols. The residual biomass presented a content of 7.36% protein, 1.11% lipids, 20.51% ash, 14.88% moisture, 50.25% total fibers, and 5.89% alginate. Preliminary screening identified N, N-(dimethylamino)-ethanol: benzyl alcohol (1.30:1) and N, N-(dimethylamino)-ethanol:1,3-propanediol (1.83:1) as the most efficient solvents for the extraction of bioactive compounds. The optimization process showed that the temperature and solid–liquid ratio significantly influenced (p < 0.05) the extraction of total phenolic compounds, phlorotannins, and the content of photosynthetic pigments. Intermediate temperatures (74.4 °C for N, N-(dimethylamino)-ethanol: benzyl alcohol (1.30:1) and 68.4 °C for N, N-(dimethylamino)-ethanol:1,3-propanediol (1.83:1), and a lower solid-to-liquid ratio (0.03) were optimal conditions to extract the low-pigment phlorotannins selectively. In contrast, higher temperatures (120 °C) maximized the extraction of phlorotannins and photosynthetic pigments. N, N-(dimethylamino)-ethanol: benzyl alcohol (1.30) extracted 110.64 mg PGE/g phlorotannins and 78.15 mg GAE/g phenolics, while N, N-(dimethylamino)-ethanol:1,3-propanediol (1.83:1) produced 21.57 mg PGE/g and 72.89 mg GAE/g, respectively. The extraction of photosynthetic pigments reached a maximum yield at 120 °C, using N, N-(dimethylamino)-ethanol: benzyl alcohol (1.30:1), with a content of 21.61 µg/g of chlorophylls and 38.11 µg/g of pheophytins, while N, N-(dimethylamino)-ethanol: 1,3-propanediol (1.83:1) provided content of 17.76 µg/g and 36.32 µg/g, respectively. The extracts exhibited antioxidant activity with 0.69 mg TE/mL in scavenging DPPH radicals, 24.42 mg TE/mL in scavenging ABTS radicals, and 2.26 mg TE/mL of iron-reducing antioxidant power. These results demonstrate the potential of DESs for the sustainable recovery of bioactive compounds from Sargassum filipendula residual biomass. Full article

(This article belongs to the Special Issue Green Separation and Purification Processes)

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28 pages, 3803 KiB

Open AccessArticle

Comparative Analysis of Five Numerical Methods and the Whale Optimization Algorithm for Wind Potential Assessment: A Case Study in Whittlesea, Eastern Cape, South Africa

by Ngwarai Shambira, Lwando Luvatsha and Patrick Mukumba

Processes 2025, 13(5), 1344; https://doi.org/10.3390/pr13051344 - 27 Apr 2025

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Abstract

This study explores the potential of wind energy to address electricity shortages in South Africa, focusing on the Ekuphumleni community in Whittlesea. Given the challenges of expanding the national grid to these areas, wind energy is considered to be a feasible alternative to [...] Read more.

This study explores the potential of wind energy to address electricity shortages in South Africa, focusing on the Ekuphumleni community in Whittlesea. Given the challenges of expanding the national grid to these areas, wind energy is considered to be a feasible alternative to provide clean, renewable energy and reduce fossil fuel dependence in this community. This research evaluates wind potential utilizing the two-parameter Weibull distribution, with scale and shape parameters estimated by five traditional numerical methods and one metaheuristic optimization technique: whale optimization algorithm (WOA). Goodness-of-fit tests, such as the coefficient of determination (R²) and wind power density error (WPDE), were utilized to determine the best method for accurately estimating Weibull scale and shape parameters. Furthermore, net fitness, which combines R² and WPDE, was employed to provide a holistic assessment of overall performance. Whittlesea showed moderate wind speeds, averaging 3.88 m/s at 10 m above ground level (AGL), with the highest speeds in winter (4.87 m/s) and optimum in July. The WOA method outperformed all five numerical methods in this study in accurately estimating Weibull distribution parameters. Interestingly, the openwind method (OWM), a numerical technique based on iterative methods, and the Brent method showed comparable performance to WOA. The wind power density was 67.29 W/m², categorizing Whittlesea’s potential as poor and suitable for small-scale wind turbines. The east wind patterns favor efficient turbine placement. The study recommends using augmented wind turbines for the site to maximize energy capture at moderate speeds. Full article

(This article belongs to the Special Issue Advanced Technologies of Renewable Energy Sources (RESs))

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23 pages, 6469 KiB

Open AccessArticle

A Collaborative Optimization Approach for Configuring Energy Storage Systems and Scheduling Multi-Type Electric Vehicles Using an Improved Multi-Objective Particle Swarm Optimization Algorithm

by Yirun Liu and Xiaolong Wu

Processes 2025, 13(5), 1343; https://doi.org/10.3390/pr13051343 - 27 Apr 2025

Viewed by 86

Abstract

Energy storage systems (ESS) and electric vehicles (EVs) play a crucial role in facilitating the grid integration of variable wind and solar power. Despite their potential, achieving coordinated operational optimization between ESS and heterogeneous EV fleets to maintain grid stability under high renewable [...] Read more.

Energy storage systems (ESS) and electric vehicles (EVs) play a crucial role in facilitating the grid integration of variable wind and solar power. Despite their potential, achieving coordinated operational optimization between ESS and heterogeneous EV fleets to maintain grid stability under high renewable penetration poses a complex technical challenge. To address this, this study develops an integrated optimization framework combining ESS capacity planning with multi-type EV scheduling strategies. For ESS deployment, a tri-objective model balances cost, wind–solar integration, and electricity deficit. A Monte Carlo simulation algorithm is used to simulate different probabilistic models of charging loads for multiple types of EVs, and a bi-objective optimization approach is used for their orderly scheduling. An improved multi-objective particle swarm optimization (IMOPSO) algorithm is proposed to resolve the coupled optimization problem. Case studies reveal that the framework achieves annual cost reductions, enhances the wind–solar integration rate, and minimizes the power deficit in the system. Full article

(This article belongs to the Section Energy Systems)

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22 pages, 6261 KiB

Open AccessFeature PaperArticle

The Development of a New Bi₁₂ZnO₂₀/AgI Heterosystem for the Degradation of Dye-Contaminated Water by Photocatalysis Under Solar Irradiation: Synthesis, Characterization and Kinetics

by Serine Madji, Mohamed Belmedani, Elhadj Mekatel, Sarra Zouaoui and Seif El Islam Lebouachera

Processes 2025, 13(5), 1342; https://doi.org/10.3390/pr13051342 - 27 Apr 2025

Viewed by 109

Abstract

This study explores the efficiency of heterogeneous photocatalysis in wastewater treatment, which is recognized for inducing significant rates of degradation and mineralization of various contaminants, including dyes. The study focuses on the development of an innovative composite via a combination of the sillenite [...] Read more.

This study explores the efficiency of heterogeneous photocatalysis in wastewater treatment, which is recognized for inducing significant rates of degradation and mineralization of various contaminants, including dyes. The study focuses on the development of an innovative composite via a combination of the sillenite type semiconductor Bi₁₂ZnO₂₀ and the halide-type semiconductor AgI. Both semiconductors were synthesized via co-precipitation, and their phases were identified using X-ray diffraction and characterized by scanning electron microscopy, Raman spectroscopy, Brunauer–Emmett–Teller analysis for specific surface area, UV–Visible diffuse reflectance spectroscopy, and the point of zero charge. The evaluation of the photocatalytic activity of the Bi₁₂ZnO₂₀/AgI heterosystem was carried out by monitoring the degradation process of Basic Blue 41 (BB41) under solar irradiation conditions. The results of this study revealed that the Bi₁₂ZnO₂₀/AgI heterosystem achieved the efficient degradation of BB41, with a removal rate of 98% after 150 min of treatment. The mineralization study showed that the TOC value decreased from 19.89 mg L⁻¹ to 6.87 mg L⁻¹, indicating that a significant portion of BB41 was mineralized. Via kinetic research, it was established that the degradation process followed a pseudo-first-order mechanism. Furthermore, recycling tests showed that the synthesized heterostructures maintained good structural stability and acceptable reusability over several cycles. These findings highlight the potential of heterogeneous photocatalysis as a promising approach to addressing environmental challenges associated with azo dyes. Full article

(This article belongs to the Special Issue Advanced Oxidation Processes for Water and Wastewater Treatment: Developments, Challenges, and Opportunities)

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14 pages, 2011 KiB

Open AccessArticle

Study and Effect of Agitation on Kojic Acid Production by Aspergillus oryzae in Liquid Fermentation

by Juan Fernando Soberón-Nakasima-Cerda, Armando Robledo-Olivo, Ana Verónica Charles-Rodríguez, Héctor A. Ruiz, Susana González-Morales and Adalberto Benavides-Mendoza

Processes 2025, 13(5), 1341; https://doi.org/10.3390/pr13051341 - 27 Apr 2025

Viewed by 106

Abstract

Kojic acid (KA) is an economically important molecule, due to its functions as an anti-inflammatory, antifungal, and facial skin-lightening agent. Considering the wide application of this metabolite, it is essential to study processes that increase or improve its production. The objective of this [...] Read more.

Kojic acid (KA) is an economically important molecule, due to its functions as an anti-inflammatory, antifungal, and facial skin-lightening agent. Considering the wide application of this metabolite, it is essential to study processes that increase or improve its production. The objective of this study was to evaluate the effect of agitation on fungal KA production. To evaluate the effect of agitation on fungal KA production, liquid medium fermentation was carried out using batch bioreactors with a capacity of one liter. The Aspergillus oryzae strain was used, with glucose as the sole carbon source. Three experimental factors were evaluated: illumination (light or darkness), agitation type (no agitation, bubbling, and tangential), and time (0, 24, 48, 72, 96, 120, 144, 168 h). The evaluated variables included pH, product-to-biomass yield, protein content, reducing sugar consumption, and KA concentration. The bubbling level with light for 144 h showed the highest efficiency by producing 7.86 ± 2.21 g KA/L. The production of KA in liquid medium with the fungus A. oryzae requires bubbling conditions with light to achieve the best yields and production. The findings in this study provide insights into the influence of agitation conditions on KA biosynthesis and its potential for scaling up industrial fermentation. However, future work could investigate the metabolic and genetic mechanisms of this enhanced production to generate more efficient biotechnological applications for KA production. Full article

(This article belongs to the Special Issue Advances in Value-Added Products from Waste)

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17 pages, 10288 KiB

Open AccessArticle

Accelerated Degradation Test and Performance Degradation Characteristics of Intelligent Circuit Breaker Control Circuit

by Zhenhua Xie, Linming Hou, Puquan He, Yizhou Cai and Yao Wang

Processes 2025, 13(5), 1340; https://doi.org/10.3390/pr13051340 - 27 Apr 2025

Viewed by 102

Abstract

With the development of intelligent grid systems, smart circuit breakers are widely used. The control circuit is the core component of the smart circuit breaker, making its performance degradation characteristics highly significant. This paper focuses on the control circuit’s accelerated degradation test and [...] Read more.

With the development of intelligent grid systems, smart circuit breakers are widely used. The control circuit is the core component of the smart circuit breaker, making its performance degradation characteristics highly significant. This paper focuses on the control circuit’s accelerated degradation test and performance degradation characteristics. First, an accelerated degradation test is designed, and a test platform is established. By analyzing the degradation mechanism of the intelligent circuit breaker control loop, the key weak links in the control loop are determined, and then the monitoring quantity is determined. Then, degradation data are preprocessed to extract features from the time, frequency, and wavelet domains. The multidimensional evaluation index model is applied to select the optimal features, fit the degradation trend, and use the fixed segmentation algorithm to divide the degradation stages and analyze the performance degradation characteristics of the control circuit. The experimental results show that the turning points of the two-stage degradation process at 85 °C, 95 °C, and 105 °C are 78.8%, 77.6%, and 77.0%, respectively. The position of the turning point is relatively fixed. The key circuit’s PSpice simulation model is built to verify the two-stage nonlinear characteristics observed in the experimental results. Finally, the results are verified by the Pearson correlation coefficient. The results show that the Pearson correlation coefficient between the simulation and accelerated life test results is above 0.9158, and the consistency between the two is high. Full article

(This article belongs to the Special Issue Fault Diagnosis Technology in Machinery Manufacturing)

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