Table of Content

28 March 2026, Volume 26 Issue 3

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Cover and Contents

The Chinese Journal of Process Engineering. 2026, 26(3):  0. 

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Review

Research progress on free radicals-mediated degradation of iodinated X-ray contrast media

Hui LIU Chenxi LIU Guoxia YIN Yulai WANG

The Chinese Journal of Process Engineering. 2026, 26(3):  223-232.  DOI: 10.12034/j.issn.1009-606X.225186

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Iodinated X-ray contrast media (ICM) is a crucial class of medical pharmaceuticals widely used for the diagnostic imaging of vascular organs and soft tissues. However, the extensive global utilization of ICM has resulted in its frequent detection in aquatic environments. ICM exhibits strong polarity and biochemical stability, making it a great challenge to effectively remove via conventional sewage treatment technologies. Recent studies have demonstrated that the migration and transformation of ICM in natural aquatic environment has led to the emergence of iodinated organic pollutants. Moreover, ICM is the primary source of organic iodine in aquatic environments and an important precursor of iodinated disinfection by-products. Consequently, the presence of ICM in aquatic environments poses a severe threat to both the ecological environment and human health, attracting extensive attention from scholars worldwide. Based on this background and the current research hotspots of ICM, this review comprehensively summarizes the pollution status of ICM, as well as its environmental fates and transformation processes. It systematically introduces the currently reported degradation technologies of ICM and their corresponding degradation mechanisms, with a focus on the roles of various free radicals involved in these degradation technologies of the ICM degradation process. Specifically, this review conducts a systematic analysis of the degradation pathways of ICM by various reactive oxygen species and identify the differences in reaction sites and mechanisms among. Furthermore, to gain insight into the generation process of iodinated organic pollutants during the degradation process of ICM, the present study performs an in-depth analysis of the transformation pathways of iodine element released during this process and finally summarizes the key steps in the generation of iodinated organic pollutants, such as iodinated disinfection by-products. These discussions will help deepen the understanding of the degradation process of ICM and provide a theoretical basis and practical reference for the development of high-efficiency and low-toxicity degradation technologies for ICM degradation.

Research Paper

Optimization of gas-liquid two-phase flow characteristic parameters in a concentric dual-tube hydraulic jet pump

Jianjun ZHU Aodong LI Yuchen JI Jianlin PENG Yongxue ZHANG Haiwen ZHU

The Chinese Journal of Process Engineering. 2026, 26(3):  233-244.  DOI: 10.12034/j.issn.1009-606X.225156

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Liquid accumulation in gas wells significantly restricts efficient natural gas extraction, presenting a substantial challenge in the industry. Hydraulic jet pumps, recognized for their simple design, lack of mechanical moving parts, and cost-effectiveness, are increasingly adopted to address this issue. However, jet pumps often exhibit limited operational efficiency, hindering broader application. This study aims to optimize the gas-liquid two-phase flow characteristics within jet pumps, enhancing both their operational efficiency and fluid discharge capacity. To achieve this, computational fluid dynamics (CFD) modeling was combined with advanced machine learning techniques. The research initially identified critical operational and structural parameters, such as the area ratio, power fluid pressure, gas volume fraction, nozzle-throat gap distance, throat length, and diffuser angle. A support vector machine (SVM) model, optimized by Bayesian methods, was then employed to predict the complex interactions among these parameters, facilitating targeted optimization. Subsequently, the NSGA-II multi-objective optimization algorithm was applied to simultaneously improve pump efficiency and discharge capacity, resulting in a Pareto optimal solution. Through detailed numerical simulations and validations, the study achieved significant performance enhancements. Specifically, the optimized jet pump configuration improved the liquid discharge rate from 42.05 m3/d to 55.24 m3/d, representing an increase of 31.40%. Additionally, operational efficiency improved from 26.50% to 30.46%, an increment of approximately 3.96 percentage points. The results conclusively demonstrate that combining numerical simulation techniques with optimized machine learning models can effectively address critical performance constraints in jet pumps. The proposed methodology not only significantly enhances fluid transport capacity but also notably improves energy efficiency. This approach provides practical insights and a robust framework for further improving hydraulic jet pump technology in complex gas-well discharge scenarios.

Analysis of dynamics and heat transfer characteristics of droplet impact on a cylindrical curved surface

Xinyu ZHANG Xiangjun ZHOU Huaqiang CHU

The Chinese Journal of Process Engineering. 2026, 26(3):  245-256.  DOI: 10.12034/j.issn.1009-606X.225182

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In the majority of prior research, the phenomenon of droplet impact on solid surfaces has predominantly been examined under conditions involving flat substrates, with pure water serving as the most frequently utilized working fluid. While such studies have provided foundational insights into droplet dynamics, their applicability remains limited, as they fail to address the complexities encountered in many industrial and engineering scenarios. By contrast, investigating the impact behavior of ethanol droplets on cylindrical curved surfaces offers substantial practical value, particularly in optimizing critical industrial processes such as spray cooling and surface coating. Beyond industrial applications, this research also contributes to advancing fundamental knowledge in multiphase flow systems, particularly in understanding how interfacial interactions between liquids and curved substrates influence spreading, rebound, and heat transfer mechanisms. This study employs experimental methods to investigate the dynamics and heat transfer mechanisms of pure ethanol droplets and ethanol-glycerol mixture droplets (with a certain amount of glycerol added) impacting overheated curved surfaces. The dynamic analysis reveals that for pure ethanol droplets, the behavioral differences caused by surface curvature primarily occur in the high Weber number (We) regime. After adding glycerol, the maximum spreading factor on concave surfaces increases with higher glycerol concentration in the droplet, whereas on convex surfaces, this relationship no longer follows a linear trend. In terms of heat transfer, the study demonstrates that the heat transfer mechanisms differ between low and high wall temperature conditions during continuous ethanol droplet impact on overheated surfaces. Moreover, there is a coupling effect between glycerol concentration and surface curvature on heat transfer characteristics. For the impact of droplets on concave surfaces, the addition of glycerol enhances heat transfer performance at low wall temperatures; whereas at high wall temperatures, when the temperature increases to a certain extent, the addition of glycerol has no significant effect. In contrast, for droplet impact on convex surfaces, glycerol addition enhances heat transfer performance only under high wall temperature conditions.

Leakage loss characteristics and structural optimization of high-pressure port in a gas wave refrigerator

Dapeng HU Xihao LIU Wanjia LI Yiming ZHAO

The Chinese Journal of Process Engineering. 2026, 26(3):  257-269.  DOI: 10.12034/j.issn.1009-606X.225196

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The leakage loss between the high-pressure port of a dual-port gas wave refrigerator and the wave rotor channel is investigated, with emphasis on the associated flow characteristics and underlying leakage mechanisms. This leakage not only leads to energy dissipation but also adversely affects the cooling efficiency of the entire system, highlighting the importance of understanding and mitigating such losses. In this work, a novel nozzle baffle configuration incorporating a sealing structure is proposed, aiming to reduce high-pressure gas leakage and improve the overall thermal performance of the gas wave refrigerator. A comprehensive numerical and experimental analysis is conducted to evaluate the influence of the baffle-rotor gap on leakage behavior. The results reveal that the clearance between the sealing baffle and the rotor plays a crucial role in determining the magnitude of leakage loss. Specifically, the introduction of a labyrinth-type sealing structure proves to be effective in impeding the undesired flow of high-pressure gas into the low-temperature expansion region, thereby significantly enhancing the cooling capability of the device. Moreover, the sealing performance is found to degrade with increasing expansion ratio and rotor speed, due to the intensification of internal pressure differentials and flow turbulence. The isentropic efficiency of the system exhibits a non-monotonic variation-rising initially and then declining—with respect to both the expansion ratio and rotational speed. Quantitatively, the application of the sealing structure leads to a maximum improvement in cooling efficiency of 2.4%, and up to 2.3% at the optimal design speed of 2500 r/min. These findings provide theoretical and practical insights into the structural optimization of gas wave refrigeration systems, and demonstrate the critical role of precision-designed sealing features in improving performance.

Preparation and performance characterization of lightweight geopolymer-based filler materials for artificial floating islands

Yao JIANG Shuang CHEN Yixue LI Jiamao LI Weiqiang FENG Chuangang FAN

The Chinese Journal of Process Engineering. 2026, 26(3):  270-279.  DOI: 10.12034/j.issn.1009-606X.225193

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In this work, silica fume was used as a dispersant to treat aluminum powder foaming agent, and lightweight geopolymer-based filler materials with different dispersant contents (Ⅰ 0wt%; Ⅱ 80wt%; Ⅲ 90wt%; Ⅳ 95wt%) were prepared. The effects of foaming agent dispersion on the fluidity, setting time, compressive strength, permeability coefficient, and durability of lightweight geopolymer were investigated in depth. Moreover, the macroscopic pore structure of the sample was characterized using a stereomicroscope. The results showed that the appropriate dispersion treatment helped to improve the physical and mechanical properties of the specimens. Sample II exhibited the optimal dispersion ratio, with a 28 d compressive strength of 3.359 MPa. The high closed porosity (88.69%) effectively reduced the permeability coefficient of the specimens (1.18×10-6 cm/s), which remained at the 10-6 order of magnitude even after 14 days of immersion. In addition, the dispersion treatment of the foaming agent not only solved the pore size problem, but also optimized the pore distribution. This study not only provides a scientific basis for controllable aluminum powder foaming technology, but also offers a new strategy for the carrier materials of artificial floating islands. The research results promote the application of geopolymer-based materials in the field of artificial floating islands and are of great significance for the utilization of marine resources. This study demonstrates that waste materials can be transformed into new materials with practical value through scientific methods and innovative technologies, which not only reduces environmental pollution but also opens up a new way for the sustainable use of resources. The preparation and performance characterization of lightweight geopolymer materials for artificial floating islands reveal the possibility of geopolymer materials being applied to artificial floating island targets.

Effect of FeCl₂ concentration on electrochemical behavior of AlCl₃-BMIC ionic liquid and alloy co-deposition

Anan SONG Tongjiang TIAN Xiuling YAN Yukun GOU Cunying XU Yixin HUA Yan LI

The Chinese Journal of Process Engineering. 2026, 26(3):  280-288.  DOI: 10.12034/j.issn.1009-606X.225109

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This study systematically investigates the influence of FeCl2 concentration on the electrochemical behavior of the AlCl3-BMIC (1-butyl-3-methylimidazolium chloride) ionic liquid system, aiming to optimize the electrolyte composition for the controllable electrodeposition of high-iron-content Fe-Al alloys. The variations in ionic conductivity and electrochemical reduction kinetics are analyzed via conductivity measurements and cyclic voltammetry (CV). The results demonstrate that the ionic conductivity of the AlCl3-BMIC-FeCl2 ionic liquid decreases linearly with increasing FeCl2 concentration. This phenomenon is attributed to the reaction between FeCl2 and [Al2Cl7]? to form bulky [Fe(AlCl4)4]2- complexes, which reduces the mobility of charge carriers. In contrast, conductivity exhibits a positive correlation with temperature, following the temperature-dependent Kohlrausch empirical formula. As the concentration increases from 10 mmol/L to 90 mmol/L, the activation energy for ionic migration slightly increases from 9.18 kJ/mol to 9.95 kJ/mol, which originates from the hindrance effect of the generated bulky [Fe(AlCl4)4]2- complex ions on ion transport. Cyclic voltammetry indicate that Fe(II) significantly inhibits the reduction of Al(III). With increasing FeCl2 concentration, the aluminum deposition potential shifts negatively, and the reduction peak current density decreases, this is directly related to the reduced concentration of the electroactive species [Al2Cl7]-. The Fe(II) reduction peak current density increases with FeCl2 concentration while its reduction potential shifts negatively, likely due to decreased activity of [Fe(AlCl4)4]2- ions and enhanced ion-pair interactions. A linear relationship between the Al(III) reduction peak current density and Fe(II) concentration reveals the inhibitory effect of Fe(II) on aluminum electrodeposition. Additionally, the potential difference between Fe(II) and Al(III) reduction gradually decreases with increasing FeCl2 concentration, facilitating the co-deposition of Fe-Al alloys. Based on this trends, Fe-Al alloys with Fe contents ranging from 13.5wt%~68.1wt% are successfully prepared by adjusting the FeCl2 concentration. Their microstructure exhibits a progressive evolution: from nodular aggregates to uniform microspheres and floral structures. These results highlight FeCl2 concentration as a key parameter for tailoring Fe-Al alloy composition and microstructure, enabling controllable synthesis of Fe-rich coatings for advanced applications.

Measurement and correlation of α-amino-ε-caprolactam solubility in different solvents

Xiaojie GUO Peng SHI Qiang REN Chunlu WANG Suping DING Bo ZHENG

The Chinese Journal of Process Engineering. 2026, 26(3):  289-302.  DOI: 10.12034/j.issn.1009-606X.225086

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As an important organic chemical intermediate, the determination of the solubility of α-amino-ε-caprolactam is a thermodynamic basis for the development of solution crystallization purification technology and product quality control. The solubility of α-amino-ε-caprolactam in various organic solvents such as N,N-dimethylformamide, acetone, 1,4-dioxane, trioctyl phosphate, toluene, p-xylene, 1,3,5-trimethylbenzene, methyl tert-butyl ether, cyclohexane, and n-hexane was measured by the static equilibrium method. The results indicated that within the temperature range of 278.15~323.15 K, the solubility of α-amino-ε-caprolactam in different solvents increased with the rise of temperature, and the solubility in different solvents generally followed the trend that it increased with the increase of the polarity of the solvent. However, there were also some exceptional cases. For instance, although methyl tert-butyl ether was polar and could form electrostatic interaction with the solute, the steric hindrance restricted its interaction with α-amino-ε-caprolactam, resulting in a relatively low solubility. In contrast, the delocalized π-electron clouds of aromatic molecules could generate π-π interactions with the conjugated regions of α-amino-ε-caprolactam, thereby enhancing the solubility. These observations indicated that dissolution behavior was influenced not only by solvent polarity but also by intermolecular interactions such as π-π stacking. The solubility data were fitted by the Apelblat, λh, quadratic polynomial, and Van't Hoff models. The correlation coefficients (R2) of all models were greater than 0.95. Among them, the quadratic polynomial model showed the best fitting effect, with an average relative deviation ranging from 0 to 1.8403% and a root mean square deviation ranging from 0 to 0.3190%. Thermodynamic parameters of the dissolution process were analyzed by the Van't Hoff equation. It was shown that ΔdisH, ΔdisS, and ΔdisG of α-amino-ε-caprolactam were positive values in both n-hexane and cyclohexane, two non-polar solvents. It indicated that the dissolution process was a non-spontaneous, endothermic process with an increase in entropy. The calculated relative contribution of enthalpy ζH was less than the relative contribution of entropy ζTS, indicating that ΔdisH contributed less to ΔdisG than ΔdisS during the dissolution process in these 10 solvents.

Study on the influence of process conditions on iron electrolysis in sulfate system

Huan YANG Ertai LEI Yuntao YANG Yongli CHEN Zhipeng TANG Jiajun YANG Xuejiao ZHOU

The Chinese Journal of Process Engineering. 2026, 26(3):  303-313.  DOI: 10.12034/j.issn.1009-606X.225155

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Against the backdrop of the global "carbon peaking and carbon neutrality" goals, as a field of high carbon emissions, the steel industry urgently needs to develop green and low-carbon metallurgy technologies to reduce carbon emissions. Electrolytic iron technology has emerged as a key research direction for low-carbon metallurgy, as it directly utilizes green electricity to drive reduction reactions and reduces fossil energy consumption associated with traditional blast furnace ironmaking. The sulfate-system electrolytic iron process exhibits promising industrial application potential due to its simplicity and low cost. However, the morphological control of iron deposits and impurity removal during electrolysis remain critical issues restricting its development. In this study, the preparation of electrolytic iron was conducted in a sulfate electrolyte system using an iron plate as the anode. The effects of electrolysis time (5~180 min), electrolysis temperature (20~80℃), Fe2+ concentration (20~100 g/L), current density (400~1200 A/m2) and cathode material (Ti, Cu, Ni, Al, Fe) on the morphology, purity, and current efficiency of electrolytic iron were systematically investigated. The results showed that the titanium cathode could significantly inhibit impurity introduction. Under the optimized conditions of an electrolysis temperature of 80℃, Fe2+ concentration of 60 g/L, current density of 1000 A/m2, and electrolysis time of 30 min, electrolytic iron products with excellent morphology and easy stripping were obtained. XRD, SEM-EDS, and dissolution analysis indicated that the as-prepared product was dominated by pure iron via synergistic regulation of multiple parameters. It exhibited a stepped morphology with clear grain boundaries, closely packed particles, and extremely few pores. The maximum purity achieved by spot scanning was 99.97wt%, and the iron purity measured by dissolution analysis was 99.94wt%. Under the optimized conditions, the current efficiency exceeded 97%, and the direct current consumption for electrolysis was approximately 4.35 kWh/kg-Fe. This research not only provides a technical path that has both cost-effective and performance advantages for the industrial production of electrolytic iron, but also provides theoretical basis and practical reference for the development of low-carbon metallurgy technology, which is of great significance to promoting the green transformation of the steel industry.

Experimental study on co-grinding and co-combustion characteristics of herbal residue and lignite

Huinian ZHOU Huibin XU Weiyu WANG Chi MA Dongxuan WANG Xuehan YANG

The Chinese Journal of Process Engineering. 2026, 26(3):  314-322.  DOI: 10.12034/j.issn.1009-606X.225073

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An experimental roller ball milling system was established to investigate the co-grinding and co-combustion characteristics of herbal residues (HR) and lignite. The effects of HR blending ratio and moisture content on the average particle size of the mixed materials were systematically examined. Thermogravimetric analysis (TGA) was employed to study the combustion behavior of HR, lignite, and their blends with different blending ratios, and the combustion kinetic parameters were determined using the Coats-Redfern model. The results demonstrated that when the HR blending ratio was below 50wt%, the particle size of the ground materials decreased with increasing HR content. For HR blending ratios exceeding 50wt%, low-moisture HR (5%~10%) exhibited superior grindability compared to lignite, resulting in further particle size reduction. In contrast, high-moisture HR (>10%) absorbed water, leading to increased fiber flexibility and greater grinding difficulty, which consequently caused an increase in particle size. The average particle size was found to increase with moisture content, with HR showing the most significant growth rate. Field emission scanning electron microscopy observations of five mixed powder samples confirmed both the promoting and inhibiting effects during co-grinding. At HR blending ratios of 10wt% and 30wt%, lignite and HR particles showed indistinguishable morphology and excellent mixing uniformity. TGA revealed that HR possessed lower activation energy and superior burnout characteristics compared to lignite. The incorporation of HR effectively introduced an ignition source that initiated combustion at lower temperatures. The released heat elevated local temperatures of the mixed fuel, thereby reducing the ignition temperature threshold and significantly improving ignition performance. The optimal combustion efficiency was achieved at an HR blending ratio of 30wt%. However, with rising moisture content, the TG curves of mixed fuels shifted toward higher temperature regions, weakening the promoting effect of HR on lignite combustion and increasing the burnout temperature of mixed samples. This study provides theoretical guidance for the resource utilization of HR and the development of co-grinding and co-combustion technology for HR-lignite mixtures.

Study on optimization of medium for collagen production by recombinant Escherichia coli based on response surface methodology

Xiaofan WANG Kaiwen CHEN Zimeng ZHANG Huixia ZHU Fenghe LI Huai WANG

The Chinese Journal of Process Engineering. 2026, 26(3):  323-332.  DOI: 10.12034/j.issn.1009-606X.225207

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The culture medium serves as the fundamental basis for recombinant Escherichia coli (E. coli) fermentation, where its composition and formulation critically govern cellular growth, the expression efficiency of target proteins (e.g., collagen), and the cost-effectiveness of industrial-scale production. This study aimed to optimize the culture medium for recombinant E. coli fermentation to improve collagen production efficiency while reducing costs. By conducting single-factor experiments, the key medium components were systematically refined, followed by the application of response surface methodology (RSM) to refine the composition of the culture medium, aiming to enhance production efficiency while reducing costs. The optimized fermentation medium formula obtained was composed of 2.85 g/L glucose, 53.85 g/L complex nitrogen source, and 64.63 mmol/L phosphate buffer. Validation experiments based on this refined formulation demonstrated that the collagen yield reached an impressive 8.62 mg/50 mL, matching that of conventional TB medium while reducing production costs by 30%, highlighting significant economic advantages. A critical innovation was the complete replacement of glucose with straw hydrolysate, which achieved 93% of the original yield, not only confirming the practicality and cost-effectiveness of utilizing agricultural waste as a sustainable feedstock but also providing robust empirical evidence to support the broader adoption of lignocellulosic biomass as a sustainable substitute for starch-derived sugars in microbial fermentation processes. Additionally, scale-up studies conducted at the 5 L bioreactor level unequivocally validated the excellent stability and scalability of the optimized medium, as both bacterial growth kinetics and collagen expression profiles remained consistently unaffected, indicating seamless transition from laboratory to pilot-scale operations. Collectively, these findings establish a solid technical foundation for the high-efficiency, low-cost biological manufacturing of collagen using recombinant E. coli as the host system, offering a transformative pathway toward more sustainable, resource-efficient bioproduction that aligns with circular economy principles while significantly advancing industrial applications in the field of recombinant protein synthesis.