South African Journal of Chemical Engineering最新文献

{"title":"Phytoremediation of young landfill leachates using Chrysopogon zizanioides: evaluation of heavy metal removal and post-treatment toxicity","authors":"Francis Toscano Mouthon ,&nbsp;Lesly Patricia Tejeda-Benitez ,&nbsp;Wilfredo Marimón-Bolívar","doi":"10.1016/j.sajce.2025.10.005","DOIUrl":"10.1016/j.sajce.2025.10.005","url":null,"abstract":"<div><div>Landfill leachates are highly complex and hazardous mixtures containing significant concentrations of heavy metals such as cadmium (Cd) and lead (Pb), alongside high chemical oxygen demand (COD). If not properly treated, these pollutants can infiltrate groundwater and surface water, causing severe environmental and health risks. The objective of this study was to evaluate the <strong>efficacy</strong> (instead of <em>effectiveness</em>) of <em>Chrysopogon zizanioides</em> (vetiver grass) in the phytoremediation of young landfill leachates, focusing on the removal of Cd, Pb, and the reduction of COD, while assessing post-treatment toxicity. The experimental setup involved growing <em>Chrysopogon zizanioides</em> in synthetic landfill leachates at concentrations of 25 %, 50 %, 75 %, and 100 %. The leachates were analyzed before and after treatment to quantify the removal efficiencies of heavy metals and COD. Additionally, the treated leachates were subjected to ecotoxicological tests using the nematode <em>Caenorhabditis elegans</em> to assess toxicity levels after phytoremediation. The results demonstrated that <em>Chrysopogon zizanioides</em> achieved maximum removal efficiencies of <strong>98</strong> <strong>%</strong> (were achieved) for Cd and Pb at 75 % leachate concentration while also significantly reducing COD levels file-uanu6k1gueymnetdxsrbsg. However, plant growth was inhibited at 100 % leachate concentration, and the removal efficiency decreased. Ecotoxicological assessments revealed that leachates treated at 75 % concentration had minimal toxic effects, indicating effective detoxification. In this sense, <em>Chrysopogon zizanioides</em> proved to be an efficient and environmentally friendly solution for the removal of heavy metals from landfill leachates, particularly at moderate concentrations. However, further optimization is needed for highly concentrated leachates, where plant growth inhibition reduces treatment efficiency. <strong>Specifically, aspects such as nutrient supplementation or staged treatment might be necessary to improve performance at 100</strong> <strong>% leachate.</strong></div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"55 ","pages":"Pages 40-49"},"PeriodicalIF":0.0,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145418928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photoelectrocatalytic degradation of tetracycline by a novel Gr /Ni-Sb-SnO2 photo-anode","authors":"Heba F. Uonis,&nbsp;Ali H. Abbar","doi":"10.1016/j.sajce.2025.10.004","DOIUrl":"10.1016/j.sajce.2025.10.004","url":null,"abstract":"<div><div>The widespread use of pharmaceutical products in pharmaceutical therapies and agriculture has led to environmental pollution worldwide. In this work, a photoelectrocatalytic (PEC) process was applied for the degradation of a typical pharmaceutical product, tetracycline (TC), via a novel graphite (Gr)/Ni-Sb-SnO₂ photo-anode. The effect of nickel doping on the catalytic activity of the photo-anode was investigated with the help of XRD, SEM, AFM, and LSV techniques. The influence of several PEC parameters such as current density, pH, and initial concentration on the degradation of TC was studied and optimized using a response surface methodology (RSM). It was found that the Gr/Ni-Sb-SnO₂ (1:5:95) is the best photo-anode for TC degradation, and that increasing the nickel content above 1 % has a negative effect on the Gr/Ni-Sb-SnO₂ efficiency. RSM was found to be effective in describing the mathematical model linking PEC variables with TC removal at a correlation coefficient of 98.89 %. A significant interaction between the variables was observed in PEC, with the square term contributing 64.94 % to the model, and current density was the most important factor affecting TC degradation. The optimal conditions were a current density of 4.6 mA/cm², pH of 4.36, an initial concentration of 43 mg/L, and a time of 150 min in which a TC removal rate of 83.7 % was achieved corresponding to a COD removal of 62.3 % at a total energy consumption of 64.46 kWh/m³. A significant synergistic effect of PEC was observed, with rate constant being 1.56 times higher than that obtained for the photocatalytic process alone. In addition, the Gr/Ni-Sb-SnO₂ (1:5:95) photo-anode exhibited excellent degradation stability after five cycles of degradation test. Hence, Gr/Ni-Sb-SnO₂ (1:5:95) may serve as a good photo-anode for the photoelectrochemical treatment of industrial wastewaters.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"55 ","pages":"Pages 24-39"},"PeriodicalIF":0.0,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145366028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced CO₂ adsorption capacity using activated serpentine: A study of process variables and breakthrough curve analysis","authors":"Alvan Ade Reza ,&nbsp;Mahidin Mahidin ,&nbsp;Yunardi Yunardi ,&nbsp;Asri Gani ,&nbsp;Edi Munawar","doi":"10.1016/j.sajce.2025.10.003","DOIUrl":"10.1016/j.sajce.2025.10.003","url":null,"abstract":"<div><div>This study investigates the optimization of CO₂ adsorption using activated serpentine in a fixed-bed reactor, focusing on the effects of particle size (50 to 150 mesh), activation temperature (650 to 850 °C), activation duration (1.5 to 4.5 h), and CO₂ flow rate (0.1 to 1.0 SLPM). Characterization results indicate that thermal activation enhances surface area, pore structure, and adsorption efficiency. Experimental findings reveal that activation at 850 °C, with a 100 mesh particle size, achieves the highest adsorption efficiency, while the 150 mesh fraction exhibits the highest adsorption rate (0.71 mL/min g). An activation duration of 1.5 h provides an optimal balance between structural stability and reactivity, whereas a flow rate of 0.5 SLPM results in the highest adsorption efficiency (R² = 99.55 %). Breakthrough curve analysis confirms that smaller particle sizes and lower flow rates extend adsorption duration and enhance overall adsorption efficiency. Kinetic modeling using the Thomas, Yoon-Nelson, and Clark models demonstrates that the Clark and Yoon-Nelson models provide the most accurate predictions, with R² values reaching up to 99.55 % and lower Reduced Chi-Square values across various experimental conditions. The optimized adsorption conditions, including 850 °C activation, 100 mesh particle size, 1.5 h activation duration, and a 0.5 SLPM flow rate, achieve a balance between adsorption capacity and kinetics. These findings contribute to the advancement of serpentine-based adsorbents for carbon capture and storage (CCS) applications, supporting efforts to mitigate industrial CO₂ emissions.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"55 ","pages":"Pages 50-62"},"PeriodicalIF":0.0,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145420017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nitrate removal from simulated wastewater by electrocoagulation: Impact of operating parameters on removal efficiency and energy consumption","authors":"Sata Kathum Ajjam ,&nbsp;Marwa Abd Aljaleel ,&nbsp;Basheer Hashem Hlihl ,&nbsp;Hameed Hussein Awlan","doi":"10.1016/j.sajce.2025.10.002","DOIUrl":"10.1016/j.sajce.2025.10.002","url":null,"abstract":"<div><div>This study concerns the electrocoagulation (EG) process that is used to remove nitrate from simulated wastewater within an electrochemical cell containing a monopolar aluminium four-electrode. There are four effected parameters were chosen as a controllable variable; initial pH, applied potential, electrolysis time, and distance between electrodes, while there to responses were investigated under effect of these variables; nitrate removal efficiency and energy consumption (EC), so the new in this work is the using of four aluminium exchangeable electrodes and the investigation four operation parameters on nitrate removal and energy consumption efficiency as well as the optimization for the system. The range for the chosen studied variables is as follows: 7-11,2-10 volts,30-90 minutes, and 1-3 cm for initial pH, applied potential, electrolysis time, and distance between electrodes, respectively. The results show that nitrate removal efficiency ranged between 79.9 and 93.0 %, where the analysis variation (ANOVA) analysis shows that the electrolysis time is the most significance parameter was effect on the nitrate removal efficiency due to its highest F-value, and followed in effect by distance between electrode, applied potential, and initial pH according to their F-values 29.57, 14.38, and 3.86 for distance between electrodes, applied potential, and initial pH respectively. The energy consumption (EC) results ranged between 1.89- and 6.45 kW hr. m^-3. On the other hand, the maximum nitrate removal efficiency is 94.84 % at the optimum conditions at 11, 4.66 volts, 90 minutes, and 1 cm for initial pH, applied potential, electrolysis time, and distance between electrodes correspondingly, while the minimum value for the EC is 0.0508 kW hr. m^-3 at 7 initial pH solution, 4.26 volt applied potential, 30 minutes electrolysis time, and 1 cm distance between electrodes.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"55 ","pages":"Pages 1-10"},"PeriodicalIF":0.0,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145340930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Green Synthesis and Characterization of ZnO Nanoparticles Using Brunfelsia americana Leaf Extract: Isotherm, Kinetics, Thermodynamic Insights and Reusability into Malachite Green Dye Removal from Aqueous Solutions","authors":"Md.Rajibul Akanda,&nbsp;Md. Foysal Hasan,&nbsp;Md. Al-Amin","doi":"10.1016/j.sajce.2025.10.001","DOIUrl":"10.1016/j.sajce.2025.10.001","url":null,"abstract":"<div><div>This study presents the eco-friendly approach for synthesizing zinc oxide nanoparticles (ZnO NPs) using <em>Brunfelsia americana</em> leaf extract as a novel bioreductant, serving dual roles as a reducing and stabilizing agent. The influence of solvent type, calcination conditions, and extract concentration on nanoparticle formation was systematically explored to optimize synthesis efficiency. A distinct color change and a UV–visible absorption peak near 360 nm confirmed the formation of ZnO NPs. Structural and morphological analyses using FTIR, XRD, SEM, and EDX revealed the presence of surface functional groups, a predominantly spherical shape, particle sizes ranging from 35 to 50 nm (average ∼45 nm), elemental composition, and a crystalline hexagonal wurtzite phase with a crystallite size of 36.09 nm and the specific surface area was calculated to be 29.63 m²/g (XRD / crystallite-based estimate). The prepared ZnO NPs were evaluated for their ability to adsorb malachite green (MG) dye from aqueous solutions. Optimal adsorption occurred under the conditions: pH_ZPC of 7.48, solution pH of 8.0, initial dye concentration of 30 mg/L, nanoparticle dosage of 0.3 g/L, contact time of 210 min and agitation speed of 300 rpm. Under these parameters, a maximum dye removal efficiency of 93.89% and an adsorption capacity of 9.39 mg/g were achieved. Reusability assessments showed efficiencies of 85.59% and 78.33% in the first and second cycles, respectively. Adsorption data aligned well with the Freundlich isotherm (R² = 0.9998) and Ho’s pseudo-second-order kinetic model (R² = 0.9958). Thermodynamic findings indicated physisorption as the dominant mechanism. Overall, the green-synthesized ZnO NPs demonstrate significant potential as a low-cost, sustainable adsorbent for dye removal, particularly in resource-limited regions such as Bangladesh.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"55 ","pages":"Pages 11-23"},"PeriodicalIF":0.0,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145340931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Efficient tofu wastewater treatment with biofiltration using OPEFB-activated carbon","authors":"Sri Suhartini ,&nbsp;Alya Vinurila ,&nbsp;Novita Ainur Rohma ,&nbsp;Andhika Putra Agus Pratama ,&nbsp;Ika Atsari Dewi ,&nbsp;Nur Hidayat ,&nbsp;Nimas Mayang Sabrina Sunyoto ,&nbsp;Riris Waladatun Nafi’ah ,&nbsp;Widya Fatriasari ,&nbsp;Lynsey Melville","doi":"10.1016/j.sajce.2025.09.012","DOIUrl":"10.1016/j.sajce.2025.09.012","url":null,"abstract":"<div><div>This study evaluates the effectiveness of biofiltration in treating tofu wastewater using a biofilter system with various media combinations, including OPEFB-derived activated carbon. The aim was to investigate the impact of media arrangement and activated carbon thickness on the reduction of pollutants such as pH, turbidity, colour, BOD, COD, and TSS. A series of experiments were conducted with different media arrangements (i.e., silica sand, activated charcoal, zeolite, and gravel) and varying activated carbon thicknesses (i.e., 10, 15, and 20 cm). The results showed that the biofilter system significantly improved wastewater quality, with the best performance observed in the S1A3 treatment, which achieved the highest removal efficiencies of 79.39% for turbidity, 68.42% for colour, 60.42% for BOD, 76.14% for COD, and 71.11% for TSS. The study suggests that biofiltration using OPEFB-activated carbon combined with silica sand, zeolite, and gravel is a promising and cost-effective method for reducing pollutants in tofu wastewater. However, further optimization and additional treatment methods are needed to meet regulatory discharge standards, particularly for BOD, COD, and TSS. The findings contribute to the development of sustainable wastewater treatment practices, with potential applications in the tofu industry.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 506-518"},"PeriodicalIF":0.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetohydrodynamic double diffusive mixed convection of power-law non-Newtonian hybrid nanofluid in rotating eccentric annuli with different positions of inner cylinder","authors":"Israt Jahan Supti,&nbsp;Md. Zahangir Hossain,&nbsp;Md. Mamun Molla","doi":"10.1016/j.sajce.2025.09.011","DOIUrl":"10.1016/j.sajce.2025.09.011","url":null,"abstract":"<div><div>The study numerically analyzes magnetohydrodynamic (MHD) double-diffusive mixed convection in a rotating eccentric annulus filled with a non-Newtonian power-law hybrid nanofluid consisting of <span><math><mrow><mi>A</mi><msub><mrow><mi>l</mi></mrow><mrow><mn>2</mn></mrow></msub><msub><mrow><mi>O</mi></mrow><mrow><mn>3</mn></mrow></msub></mrow></math></span> and <span><math><mrow><mi>F</mi><msub><mrow><mi>e</mi></mrow><mrow><mn>3</mn></mrow></msub><msub><mrow><mi>O</mi></mrow><mrow><mn>4</mn></mrow></msub></mrow></math></span> nanoparticles suspended in water, considering various placements of the inner cylinder. The study utilizes the Galerkin weighted residual finite element method (GFEM) for the analysis. In this structure, the nanofluid fills the gap between the cylinders, keeping the outside circle of the geometry cold and the inner circle hot. In this structure, the nanofluid fills the gap between the cylinders, keeping the outside circle of the geometry cold and the inner circle hot. This study explores the effects of multiple governing parameters, including a power-law index varying between 0.7 and 1.3, nanoparticle concentrations from 0% to 2%, Hartmann numbers between 0 and 30, and buoyancy ratios ranging from −1 to 1. The analysis also considers Reynolds numbers in the range of 200 to 600, Richardson numbers from 0 to 5, Lewis numbers between 1 and 10, and angular velocity between −20 and 20 while maintaining a constant Prandtl number of 6.8377. In addition, heat and mass transfer rates are evaluated in terms of Nusselt and Sherwood numbers, and visualizations such as streamlines, isotherms, and concentration contours are presented. The heat and mass transfer rates remain nearly unchanged regardless of whether the inner cylinder rotates clockwise or counterclockwise. The results show that the heat and mass transfer rates remain nearly unchanged regardless of whether the inner cylinder rotates clockwise or counterclockwise. An increase in the Hartmann number leads to an enhancement in heat transfer, while it simultaneously reduces the mass transfer rate. On the other hand, a higher power-law index results in a decline in both heat and mass transfer rates. Conversely, a rise in the buoyancy ratio contributes to the enhancement of both thermal and mass transport. The novelty of this study is how varying angular velocities (positive and negative) influence heat and mass transport in a power-law non-Newtonian fluid under MHD effects. It offers a new parametric analysis of forced and free convection interactions using Reynolds number, Hartmann number, Richardson number, and angular velocity. For a non-rotating inner cylinder at power-law index = 0.7, the average Nusselt number decreases by 36.89%, while the average Sherwood number decreases by 17.14% as the Hartmann number increases from 0 to 30.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 546-566"},"PeriodicalIF":0.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synergizing the pore structure and functionality of CAU-10-series metal-organic framework materials for energy-efficient ammonia separation","authors":"Shih-Yuan Chen ,&nbsp;Chung-Kai Chang ,&nbsp;Martin Keller ,&nbsp;Genki Horiguchi ,&nbsp;Takehisa Mochizuki ,&nbsp;Dun-Yen Kang","doi":"10.1016/j.sajce.2025.09.014","DOIUrl":"10.1016/j.sajce.2025.09.014","url":null,"abstract":"<div><div>Alumina-based metal–organic framework materials (Al-based MOFs) are integrated into an ammonia (NH₃) synthesis process to achieve 1–5 % NH₃ adsorptive separation at 25–100 °C and 1 bar (corresponding to an NH₃ partial pressure of ∼1000–5000 Pa). Monte Carlo simulation and temperature-programmed analysis are employed to clarify the crucial role of functional groups on the pore surface and shape of Al-based MOFs and their effects on NH₃ interactions. This approach focuses on specific surface areas, which contrasts with traditional approaches. Among these Al-based MOFs, CAU-10-OH composed of octahedral Al species linked to 5-hydroxyisophthalic acid exhibit high NH₃ adsorption capacity (3.6–1.8 mmol <em>g</em>⁻¹) at 25–100 °C and stability over 15 adsorption–desorption cycles (∼180 h). This performance is comparable to that of microporous ZSM-5 zeolitic materials and significantly exceeds that of silica and activated carbon. NH₃ adsorption and desorption heat (60 kJ mol⁻¹) on CAU-10-OH with hydroxyl groups located in cage-like pores (2.41 Å) are suitable for low-concentration, ambient-temperature NH₃ separation. Integrating CAU-10-OH at 25 °C downstream of Ru-catalyzed mild NH₃ synthesis exhibits rapid NH₃ adsorption, proving its practical efficacy for synthesis and separation under mild conditions. The proposed method can potentially enhance energy efficiency and reduce capital costs by minimizing processing steps.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 567-581"},"PeriodicalIF":0.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145265161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of the influence of the role of the Hf dopant concentration variation on the stability to degradation of ZrO2 ceramics considered as materials for solid oxide fuel cells","authors":"Sh.G Giniyatova ,&nbsp;D.I. Shlimas ,&nbsp;D.B. Borgekov ,&nbsp;A.T. Zhumazhanova ,&nbsp;N. Volodina ,&nbsp;A.L. Kozlovskiy","doi":"10.1016/j.sajce.2025.09.013","DOIUrl":"10.1016/j.sajce.2025.09.013","url":null,"abstract":"<div><div>The key objective of this study is to determine the effect of hafnium stabilization of ZrO₂ ceramics and to identify its role in hardening and enhancement of resistance to degradation processes caused by the use of these ceramics as anode materials in solid oxide fuel cells. According to the X-ray structural analysis and Raman spectroscopy data, it was found that with an elevation in the Hf dopant concentration, the HfO₂ phase is formed in the composition of the ceramics, which has a similar structural motif to the monoclinic phase of ZrO₂, resulting in the formation of a continuous substitution solid solution of ZrO₂/HfO₂, and a change in the crystal lattice parameters of the monoclinic phase of ZrO₂ indicates the substitution of Zr⁴⁺ ions by Hf⁴⁺ ions, leading to a growth in the crystal lattice parameters, and consequently, the formation of oxygen vacancies. According to the assessment of the mechanical and strength properties of Zr(Hf)O₂ ceramics, it was found that the formation of inclusions in the ceramics in the form of HfO₂, which form a continuous solid solution at low concentrations, leads to an increase in resistance to external influences within 35 – 40 % compared to unstabilized ZrO₂ ceramics, but a rise in the density of oxygen vacancies above 4.4 × 10¹⁸, alongside the formation of T-defects in the structure leads to a decrease in resistance to external influences, but the strength parameters exceed the values for unstabilized ZrO₂ ceramics. Evaluation of the efficiency of using Zr(Hf)O₂ ceramics as anode materials revealed that at low dopant concentrations, not only an increase in specific power is observed, but also the stability of electrochemical parameters is maintained in the case of prolonged high-temperature exposure, which has a negative impact on maintenance of the performance of solid oxide fuel cells.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 533-545"},"PeriodicalIF":0.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Factors contributing to reduced photocatalytic activity in Cu-loaded TiO2/activated carbon composites for methylene blue degradation","authors":"Nur Karimah ,&nbsp;Risna Citra Andiani ,&nbsp;Wahyu Prasetyo Utomo ,&nbsp;Ade Irma Rozafia ,&nbsp;Nor Farida ,&nbsp;Afifah Rosyidah ,&nbsp;Rui Liu ,&nbsp;Qili Xu ,&nbsp;Djoko Hartanto","doi":"10.1016/j.sajce.2025.09.015","DOIUrl":"10.1016/j.sajce.2025.09.015","url":null,"abstract":"<div><div>TiO₂ is a semiconductor widely used in photocatalytic applications due to its excellent chemical stability, yet it has a low surface area. Incorporating TiO₂ on the surface of activated carbon via a hydrothermal process could enlarge its surface area, and therefore the photocatalytic activity. Theoretically, metal deposition on the surface of TiO₂ could create a Schottky junction, which suppresses charge recombination and enhances photocatalytic activity. Herein, we report Cu deposition on the surface of TiO₂ anchored on activated carbon (Cu-TiO₂/AC) for photocatalytic degradation of methylene blue. The Cu was deposited by a photodeposition process under UV irradiation. In contrast to the conventional hypothesis, that the Cu deposition on TiO₂/AC could exhibit an enhanced photocatalytic activity, our current result shows that the material exhibits a decrease in photocatalytic activity compared to the pristine TiO₂/AC. The same trend was also observed in other TiO₂ samples with different morphology upon Cu photodeposition. The decrease in photocatalytic activity could be correlated with the size of Cu nanoparticles and the oxidation state of Cu species. The photodeposition typically produces a relatively large Cu nanoparticle, which may serve as the recombination center for the charge carriers. Moreover, the existence of Cu⁺ and Cu²⁺ species, in addition to Cu⁰, could consume the transferred e^- from TiO₂, decreasing the e^- efficiency. This work implies that ensuring the small particle size and the existence of monovalent Cu⁰ species are critical factors for using Cu as a co-catalyst in photocatalyst materials.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 582-596"},"PeriodicalIF":0.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145265160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}