Pub Date : 2026-01-01Epub Date: 2025-12-17DOI: 10.1016/j.sajce.2025.12.011
Muhammad Irfan Qadir , Ali B.M. Ali , Hakim AL Garalleh , Usman Majeed , Faheem ul Islam , Ali Raza , Sami Ullah Khan , Nodira Nazarova , Manish Gupta , M. Waqas , M. Ijaz Khan
This communication aims to develop a fractional mathematical model for flow of generalized Brinkman fluid with utilization of nanoparticles over vertically heated plate. A suspension of titanium oxide and molybdenum disulfide with water ) base fluid is considered to evaluates the heat transfer enhancement. Thermal properties of nanoparticles is presented. The problem is entertained with amplification of slip features. After formulating the governing equation, a novel fractional scheme namely Prabhakar technique is implemented. The integration framework is facilitated with famous Laplace technique. Physical interpretation of results has been revealed with different values of parameters. It is observed that velocity profile reduces due to Brinkman fluid parameter. Interaction of velocity slip parameter leads to decrement of velocity profile. Moreover, change in nanoparticles volume fraction leads to enhancement of temperature profile.
{"title":"Heat transfer enhancement in fractional Brinkman nanofluids: Effects of thermal and nanoparticle geometry","authors":"Muhammad Irfan Qadir , Ali B.M. Ali , Hakim AL Garalleh , Usman Majeed , Faheem ul Islam , Ali Raza , Sami Ullah Khan , Nodira Nazarova , Manish Gupta , M. Waqas , M. Ijaz Khan","doi":"10.1016/j.sajce.2025.12.011","DOIUrl":"10.1016/j.sajce.2025.12.011","url":null,"abstract":"<div><div>This communication aims to develop a fractional mathematical model for flow of generalized Brinkman fluid with utilization of nanoparticles over vertically heated plate. A suspension of titanium oxide <span><math><mrow><mo>(</mo><mrow><mi>T</mi><mi>i</mi><msub><mi>O</mi><mn>2</mn></msub></mrow><mo>)</mo></mrow></math></span> and molybdenum disulfide <span><math><mrow><mo>(</mo><mrow><mi>M</mi><mi>o</mi><msub><mi>S</mi><mn>2</mn></msub></mrow><mo>)</mo></mrow></math></span> with water <span><math><mrow><mo>(</mo><msub><mi>H</mi><mn>2</mn></msub><mi>O</mi></mrow></math></span>) base fluid is considered to evaluates the heat transfer enhancement. Thermal properties of nanoparticles is presented. The problem is entertained with amplification of slip features. After formulating the governing equation, a novel fractional scheme namely Prabhakar technique is implemented. The integration framework is facilitated with famous Laplace technique. Physical interpretation of results has been revealed with different values of parameters. It is observed that velocity profile reduces due to Brinkman fluid parameter. Interaction of velocity slip parameter leads to decrement of velocity profile. Moreover, change in nanoparticles volume fraction leads to enhancement of temperature profile.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"55 ","pages":"Pages 493-500"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145839722","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}
Pub Date : 2026-01-01Epub Date: 2025-12-28DOI: 10.1016/j.sajce.2025.12.017
Zahrotul Istiqomah , Holilah , Didik Prasetyoko , Sri Sunarmi , Hendro Juwono , Agus Wedi Pratama , Mohd Saiful Asmal Rani , Dina Wahyu Indriani , Victor Feizal Knight , Mohd Nor Faiz Norrrahim
Filter paper waste represents a significant yet underutilized feedstock for producing nanocellulose, a high-value nanomaterial essential for bioplastics and nanocomposites due to its biodegradability and mechanical strength. Valorizing this laboratory byproduct supports circular economy principles by converting waste into functional materials. In this study, nanocellulose was successfully isolated from filter paper waste (FPW). Cellulose extracted from the FPW was converted into nanocrystalline cellulose (NCC) through acid hydrolysis using two inorganic acids (sulfuric and hydrochloric) and two organic acids (citric and formic). The results revealed that acid type significantly influences particle morphology: hydrolysis with inorganic acids yielded spherical NCC particles, while the organic acids produced thin rod-shaped NCC. The average particle diameters of NCC from sulfuric and hydrochloric acid were 42.08 nm and 53.14 nm, respectively. FPW-NCH exhibited the highest crystallinity (87.40%), while FPW-NCS showed the lowest thermal stability (degradation onset at 220 °C). These findings demonstrate that simple acid selection is a critical tool for tailoring nanocellulose properties for specific end-use requirements
{"title":"Spherical and rod-shaped nanocellulose from filter paper waste: A comparative study of acid hydrolysis","authors":"Zahrotul Istiqomah , Holilah , Didik Prasetyoko , Sri Sunarmi , Hendro Juwono , Agus Wedi Pratama , Mohd Saiful Asmal Rani , Dina Wahyu Indriani , Victor Feizal Knight , Mohd Nor Faiz Norrrahim","doi":"10.1016/j.sajce.2025.12.017","DOIUrl":"10.1016/j.sajce.2025.12.017","url":null,"abstract":"<div><div>Filter paper waste represents a significant yet underutilized feedstock for producing nanocellulose, a high-value nanomaterial essential for bioplastics and nanocomposites due to its biodegradability and mechanical strength. Valorizing this laboratory byproduct supports circular economy principles by converting waste into functional materials. In this study, nanocellulose was successfully isolated from filter paper waste (FPW). Cellulose extracted from the FPW was converted into nanocrystalline cellulose (NCC) through acid hydrolysis using two inorganic acids (sulfuric and hydrochloric) and two organic acids (citric and formic). The results revealed that acid type significantly influences particle morphology: hydrolysis with inorganic acids yielded spherical NCC particles, while the organic acids produced thin rod-shaped NCC. The average particle diameters of NCC from sulfuric and hydrochloric acid were 42.08 nm and 53.14 nm, respectively. FPW-NCH exhibited the highest crystallinity (87.40%), while FPW-NCS showed the lowest thermal stability (degradation onset at 220 °C). These findings demonstrate that simple acid selection is a critical tool for tailoring nanocellulose properties for specific end-use requirements</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"55 ","pages":"Pages 551-559"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145924092","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}
Pub Date : 2026-01-01Epub Date: 2026-01-06DOI: 10.1016/j.sajce.2025.12.016
P.O. Oghenerukevwe , F Onyiriuka , T.F. Adepoju , S. Enomah , M.M. Mundu , N. Muhammed , N. Aisha , I.U. Usen , O.D. Oghenejabor
In the oil and gas sector, corrosion results in catastrophic failures, leaks, and equipment degradation that cause enormous financial losses (billions of dollars every year), serious safety risks (fires, explosions, exposure to poisonous H2S), and significant environmental pollution (infection of land and water). Corrosive agents including H2S, CO2, water, and high temperatures cause asset integrity to be compromised, production to be disrupted by unplanned shutdowns, and maintenance, repair, and replacement costs to rise. Hence, this study attempt to minimize the corrosion rate (CR), and maximize the inhibition efficiency (IE) in oil and gas industry, response surface methodology and artificial neural network tools were used to study the effects of inhibition concentration, temperature, and time of the adsorption corrosion inhibition of 42CrMo4 steel in an acidified large Maradol Leaf Extract (LMLE) of green biomass. The phytochemicals analysis of the extract was examined, and the elemental composition of 42CrMo4 steel was ascertained. The weight loss method was computed via gravimetric analysis. The kinetic and thermodynamics parameters were carried out, while the adsorption isotherm was carried out via Langmuir, Frumkin, Temkin, and Flory-Huggin isotherms.
Results shows that the compositions of the steel was majorly iron (Fe) contained 97.26%. The phytochemical analysis of the extract indicated the presence of flavonoids, phenols, saponins, alkaloids, tannins, steroids, and terpenoids found in organic biomass extract. Process modeling and optimization by central composite rotatable design (in RSM) shows a validated average minimum CR of 12.60 mm/yr and the optimum IE of 91.40%, while genetic algorithms (in ANN) validated an average minimum CR of 9.70 mm/yr and the optimum IE of 94.12%, respectively. From isotherms study, Langmuir isotherm model was found best fitted and described the corrosion inhibition mechanism of 42CrMo4 steel. Based on thermodynamic data, the negative ∆Gads from - 73.42 to - 140.42 kJ/mol connote chemisorptions adsorptions.
The study concluded that the extract of large Maradol leaf when treated with 15% hydrochloric acid could serve inhibitor for treatment of 42CrMo4 steel corrosion in an oil well environment.
{"title":"Regression analysis of corrosion inhibition of 42CrMo4 steel: a case study of acidified large Maradol leaf extract, kinetic, thermodynamics, adsorptions, and process parameter optimization","authors":"P.O. Oghenerukevwe , F Onyiriuka , T.F. Adepoju , S. Enomah , M.M. Mundu , N. Muhammed , N. Aisha , I.U. Usen , O.D. Oghenejabor","doi":"10.1016/j.sajce.2025.12.016","DOIUrl":"10.1016/j.sajce.2025.12.016","url":null,"abstract":"<div><div>In the oil and gas sector, corrosion results in catastrophic failures, leaks, and equipment degradation that cause enormous financial losses (billions of dollars every year), serious safety risks (fires, explosions, exposure to poisonous H<sub>2</sub>S), and significant environmental pollution (infection of land and water). Corrosive agents including H<sub>2</sub>S, CO<sub>2</sub>, water, and high temperatures cause asset integrity to be compromised, production to be disrupted by unplanned shutdowns, and maintenance, repair, and replacement costs to rise. Hence, this study attempt to minimize the corrosion rate (CR), and maximize the inhibition efficiency (IE) in oil and gas industry, response surface methodology and artificial neural network tools were used to study the effects of inhibition concentration, temperature, and time of the adsorption corrosion inhibition of 42CrMo4 steel in an acidified large <em>Maradol</em> Leaf Extract (LMLE) of green biomass. The phytochemicals analysis of the extract was examined, and the elemental composition of 42CrMo4 steel was ascertained. The weight loss method was computed via gravimetric analysis. The kinetic and thermodynamics parameters were carried out, while the adsorption isotherm was carried out via Langmuir, Frumkin, Temkin, and Flory-Huggin isotherms.</div><div>Results shows that the compositions of the steel was majorly iron (Fe) contained 97.26%. The phytochemical analysis of the extract indicated the presence of flavonoids, phenols, saponins, alkaloids, tannins, steroids, and terpenoids found in organic biomass extract. Process modeling and optimization by central composite rotatable design (in RSM) shows a validated average minimum CR of 12.60 mm/yr and the optimum IE of 91.40%, while genetic algorithms (in ANN) validated an average minimum CR of 9.70 mm/yr and the optimum IE of 94.12%, respectively. From isotherms study, Langmuir isotherm model was found best fitted and described the corrosion inhibition mechanism of 42CrMo4 steel. Based on thermodynamic data, the negative ∆G<sub>ads</sub> from - 73.42 to - 140.42 kJ/mol connote chemisorptions adsorptions.</div><div>The study concluded that the extract of <em>large Maradol</em> leaf when treated with 15% hydrochloric acid could serve inhibitor for treatment of 42CrMo4 steel corrosion in an oil well environment.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"55 ","pages":"Pages 518-530"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145924093","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}
Pub Date : 2026-01-01Epub Date: 2025-10-23DOI: 10.1016/j.sajce.2025.10.005
Francis Toscano Mouthon , Lesly Patricia Tejeda-Benitez , Wilfredo Marimón-Bolívar
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 efficacy (instead of effectiveness) of Chrysopogon zizanioides (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 Chrysopogon zizanioides 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 Caenorhabditis elegans to assess toxicity levels after phytoremediation. The results demonstrated that Chrysopogon zizanioides achieved maximum removal efficiencies of 98% (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, Chrysopogon zizanioides 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. Specifically, aspects such as nutrient supplementation or staged treatment might be necessary to improve performance at 100% leachate.
{"title":"Phytoremediation of young landfill leachates using Chrysopogon zizanioides: evaluation of heavy metal removal and post-treatment toxicity","authors":"Francis Toscano Mouthon , Lesly Patricia Tejeda-Benitez , 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":"2026-01-01","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}
Pub Date : 2026-01-01Epub Date: 2025-11-15DOI: 10.1016/j.sajce.2025.11.008
Aisyah Alifatul Zahidah Rohmah , Wahyu Meka , Ary Bachtiar Khrisna Putra , Ali Altway , Ardi Nugroho , Tri Widjaja
Coal combustion intensifies carbon emissions, contributing to global warming. This study explores co-firing coal with biomass sources—rice husks, sawdust, and cocopeat—and examines the role of calcium carbonate (CaCO₃) in reducing slagging. The research was conducted in three stages: (1) laboratory-scale analysis for raw material characterization, (2) prototype-scale combustion testing for efficiency and emissions, and (3) full-scale evaluation in a coal-fired power plant. Laboratory tests identified a 50% rice husk (RH) – 50% sawdust (SW) mixture as optimal, with a calorific value of 15,788.324 kJ/kg and a low alkali index (0.11). Prototype testing showed that emissions remained within regulatory limits, and CaCO₃ addition effectively reduced SO₂, NOₓ, and CO emissions while increasing SO₃ and SiO₂ retention in bottom ash, mitigating slagging risks. However, CaCO₃ exhibited limited and inconsistent effectiveness, making it unsuitable for large-scale application. Full-scale trials demonstrated that co-firing improved boiler efficiency (83.46% with 5% biomass – 95% coal co-firing vs. 83.65% with 100% coal), with stable power output (396–400 MW) and a fuel consumption of 0.6 kg/kWh. Sawdust contributed to combustion stability due to its lower porosity, while rice husks enhanced airflow, accelerating combustion. Slagging and fouling indices indicated a high slagging potential (category 6) for sawdust and cocopeat, but mixed biomass variables exhibited reduced slagging risk (category 5). Cocopeat had the highest sodium fouling and slagging indices (1.41, 1.54, 1.56), making it unsuitable for co-firing. Community involvement in biomass procurement engaged 266 stakeholders, though seasonal limitations required external sourcing. Additionally, training programs in organic fertilizer production were implemented to support biomass sustainability. Overall, this study demonstrates that biomass–coal co-firing represents a viable pathway for cleaner energy production that simultaneously provides economic and environmental benefits.
{"title":"Engineering study of coal co-firing based on biomass mixture and slagging-fouling control in the steam power plant","authors":"Aisyah Alifatul Zahidah Rohmah , Wahyu Meka , Ary Bachtiar Khrisna Putra , Ali Altway , Ardi Nugroho , Tri Widjaja","doi":"10.1016/j.sajce.2025.11.008","DOIUrl":"10.1016/j.sajce.2025.11.008","url":null,"abstract":"<div><div>Coal combustion intensifies carbon emissions, contributing to global warming. This study explores co-firing coal with biomass sources—rice husks, sawdust, and cocopeat—and examines the role of calcium carbonate (CaCO₃) in reducing slagging. The research was conducted in three stages: (1) laboratory-scale analysis for raw material characterization, (2) prototype-scale combustion testing for efficiency and emissions, and (3) full-scale evaluation in a coal-fired power plant. Laboratory tests identified a 50% rice husk (RH) – 50% sawdust (SW) mixture as optimal, with a calorific value of 15,788.324 kJ/kg and a low alkali index (0.11). Prototype testing showed that emissions remained within regulatory limits, and CaCO₃ addition effectively reduced SO₂, NOₓ, and CO emissions while increasing SO₃ and SiO₂ retention in bottom ash, mitigating slagging risks. However, CaCO₃ exhibited limited and inconsistent effectiveness, making it unsuitable for large-scale application. Full-scale trials demonstrated that co-firing improved boiler efficiency (83.46% with 5% biomass – 95% coal co-firing vs. 83.65% with 100% coal), with stable power output (396–400 MW) and a fuel consumption of 0.6 kg/kWh. Sawdust contributed to combustion stability due to its lower porosity, while rice husks enhanced airflow, accelerating combustion. Slagging and fouling indices indicated a high slagging potential (category 6) for sawdust and cocopeat, but mixed biomass variables exhibited reduced slagging risk (category 5). Cocopeat had the highest sodium fouling and slagging indices (1.41, 1.54, 1.56), making it unsuitable for co-firing. Community involvement in biomass procurement engaged 266 stakeholders, though seasonal limitations required external sourcing. Additionally, training programs in organic fertilizer production were implemented to support biomass sustainability. Overall, this study demonstrates that biomass–coal co-firing represents a viable pathway for cleaner energy production that simultaneously provides economic and environmental benefits.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"55 ","pages":"Pages 191-221"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577225","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}
Natural convection within enclosed cavities plays a critical role in heat and mass transfer across a wide range of engineering applications. Buoyancy flows are a fundamental aspect of many optimized systems currently deployed, including passive cooling of electronic devices, thermoregulation of solar collectors, and insulation of buildings to store energy used by aerospace systems. Recent advancements in nanofluids, magnetohydrodynamics (MHD), and smart materials have increased the functional applicability of natural-convection-based systems, and modern forms of the Finite Element Method (FEM) have become essential in the accurate modelling of heat and fluid flow in geometrically complex enclosures. The review explores the dynamic fields in detail but with particular focus on how they are applicable in heat exchangers in industry, microfluidic devices, biomedical incubators, and environmental ventilation systems. The review further explores localized heat sources, vortex formation due to embedded obstacles, porous media effects, and the synergistic influence of thermal and magnetic fields. This review investigates how integrating the Finite Element Method (FEM) with artificial intelligence, entropy-based optimization, and experimental validation can transform the design and advancement of next-generation thermal management systems. The findings underscore FEM’s utility as a multi-physics simulation tool for real-world thermal challenges, with particular relevance to South Africa’s growing demand for energy-efficient buildings, renewable energy solutions, and sustainable manufacturing technologies.
{"title":"A comprehensive review on natural convection in various shaped enclosures by FEM: Engineering applications","authors":"Asif Hasan, Mohammad Mokaddes Ali, Shakhawat Hossain, Neamul Haque Siam, Asaduzzaman Rony, Al-Amin Shohan","doi":"10.1016/j.sajce.2025.08.009","DOIUrl":"10.1016/j.sajce.2025.08.009","url":null,"abstract":"<div><div>Natural convection within enclosed cavities plays a critical role in heat and mass transfer across a wide range of engineering applications. Buoyancy flows are a fundamental aspect of many optimized systems currently deployed, including passive cooling of electronic devices, thermoregulation of solar collectors, and insulation of buildings to store energy used by aerospace systems. Recent advancements in nanofluids, magnetohydrodynamics (MHD), and smart materials have increased the functional applicability of natural-convection-based systems, and modern forms of the Finite Element Method (FEM) have become essential in the accurate modelling of heat and fluid flow in geometrically complex enclosures. The review explores the dynamic fields in detail but with particular focus on how they are applicable in heat exchangers in industry, microfluidic devices, biomedical incubators, and environmental ventilation systems. The review further explores localized heat sources, vortex formation due to embedded obstacles, porous media effects, and the synergistic influence of thermal and magnetic fields. This review investigates how integrating the Finite Element Method (FEM) with artificial intelligence, entropy-based optimization, and experimental validation can transform the design and advancement of next-generation thermal management systems. The findings underscore FEM’s utility as a multi-physics simulation tool for real-world thermal challenges, with particular relevance to South Africa’s growing demand for energy-efficient buildings, renewable energy solutions, and sustainable manufacturing technologies.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 308-334"},"PeriodicalIF":0.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144888714","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}
Pub Date : 2025-10-01Epub Date: 2025-07-28DOI: 10.1016/j.sajce.2025.07.011
W.W. Focke
Physical property models were developed to predict temperature-dependent multicomponent data using only temperature-independent binary parameters and pure component property temperature dependence. The Kolmogorov-Arnold representation theory was used to extend the linear blending rules and the Padé-like expressions describing the variation of physical properties of ideal solutions with composition. The effectiveness of correlating density, viscosity, refractive index and surface tension using this concept was tested. Ten ternary systems at either three or four different temperatures were regressed and compared to an ideal solution case. It was found that the four-parameter Kolmogorov-Arnold (KA) model performed excellently when the data regression included the full datasets. Unfortunately, the KA model may be too flexible, leading to overfitting binary data when applied to predicting ternary data.
{"title":"Mixture models inspired by the Kolmogorov-Arnold representation theorem","authors":"W.W. Focke","doi":"10.1016/j.sajce.2025.07.011","DOIUrl":"10.1016/j.sajce.2025.07.011","url":null,"abstract":"<div><div>Physical property models were developed to predict temperature-dependent multicomponent data using only temperature-independent binary parameters and pure component property temperature dependence. The Kolmogorov-Arnold representation theory was used to extend the linear blending rules and the Padé-like expressions describing the variation of physical properties of ideal solutions with composition. The effectiveness of correlating density, viscosity, refractive index and surface tension using this concept was tested. Ten ternary systems at either three or four different temperatures were regressed and compared to an ideal solution case. It was found that the four-parameter Kolmogorov-Arnold (KA) model performed excellently when the data regression included the full datasets. Unfortunately, the KA model may be too flexible, leading to overfitting binary data when applied to predicting ternary data.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 89-98"},"PeriodicalIF":0.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144773212","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}
Pub Date : 2025-10-01Epub Date: 2025-07-11DOI: 10.1016/j.sajce.2025.07.002
Major M. Mabuza , Glory N. Makuwa
The growing global concern over greenhouse gas emissions, specifically carbon dioxide (CO2), has led to extensive research efforts to develop innovative materials and technologies to combat the impacts of climate change. Among these materials, metal-organic frameworks (MOFs) have received significant attention in science due to their distinctive structural and adsorption properties. Within this context, magnesium-based-MOF-74 (Mg-MOF-74) has emerged as a potential candidate for efficient post-combustion CO2 capture. Mg-MOF-74 is a porous material that significantly removes CO2 from gas mixtures by adsorption. Its porous structure, with accessible magnesium ions, enables selective CO2 binding. The MOF has a high selectivity for CO2 and may be reused with heat or pressure adjustments. This study undertakes a comprehensive exploration of the synthesis, characterization, and potential practical applications of Mg-MOF-74, with a particular emphasis on the effect of synthesis conditions on the material’s efficacy as a sustainable solution for reducing CO2 emissions from typical coal-fired power plants.
The synthesis of Mg-MOF-74 was conducted at various reaction temperatures (100 °C, 110 °C, and 125 °C) and time (8 and 24 h). Characterization techniques employed include X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Fourier-Transform Infrared Spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) surface area analysis, and Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDX). The XRD data highlight temperature and time effects on crystallinity, with 100 °C for 24 h yielding well-defined structures indicating higher crystallinity than other conditions. The TGA revealed that the synthesized material is thermally stable up to 600 °C. The FTIR analysis identifies critical functional groups, such as C = O, Mg-O, and C = C groups, oxygen-containing functional groups are prime for CO2 capture. The low-pressure gas nitrogen gas adsorption (BET) study revealed Type III isotherms, signifying microporous and mesoporous features with maximum BET surface area of 24 m2/g, Langmuir surface area of 612 m2/g and varying pore sizes ranging between 8.48 and 10.13 nm. Low-pressure gas adsorption (LPGA) using CO2 gas was used to evaluate the materials' adsorption capacity. Results showed that increasing the synthesis temperature to 125 °C increased the adsorption capacity to a maximum of 31 cm3/g. The SEM micrographs display diverse morphologies with irregular patterns and cloud-like structures across samples.
{"title":"Development and characterization of magnesium-derived metal-organic framework-74 for post-combustion CO2 capture applications","authors":"Major M. Mabuza , Glory N. Makuwa","doi":"10.1016/j.sajce.2025.07.002","DOIUrl":"10.1016/j.sajce.2025.07.002","url":null,"abstract":"<div><div>The growing global concern over greenhouse gas emissions, specifically carbon dioxide (CO<sub>2</sub>), has led to extensive research efforts to develop innovative materials and technologies to combat the impacts of climate change. Among these materials, metal-organic frameworks (MOFs) have received significant attention in science due to their distinctive structural and adsorption properties. Within this context, magnesium-based-MOF-74 (Mg-MOF-74) has emerged as a potential candidate for efficient post-combustion CO<sub>2</sub> capture. Mg-MOF-74 is a porous material that significantly removes CO<sub>2</sub> from gas mixtures by adsorption. Its porous structure, with accessible magnesium ions, enables selective CO<sub>2</sub> binding. The MOF has a high selectivity for CO<sub>2</sub> and may be reused with heat or pressure adjustments. This study undertakes a comprehensive exploration of the synthesis, characterization, and potential practical applications of Mg-MOF-74, with a particular emphasis on the effect of synthesis conditions on the material’s efficacy as a sustainable solution for reducing CO<sub>2</sub> emissions from typical coal-fired power plants.</div><div>The synthesis of Mg-MOF-74 was conducted at various reaction temperatures (100 °C, 110 °C, and 125 °C) and time (8 and 24 h). Characterization techniques employed include X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Fourier-Transform Infrared Spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) surface area analysis, and Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDX). The XRD data highlight temperature and time effects on crystallinity, with 100 °C for 24 h yielding well-defined structures indicating higher crystallinity than other conditions. The TGA revealed that the synthesized material is thermally stable up to 600 °C. The FTIR analysis identifies critical functional groups, such as <em>C</em> = <em>O</em>, Mg-O, and <em>C</em> = <em>C</em> groups, oxygen-containing functional groups are prime for CO<sub>2</sub> capture. The low-pressure gas nitrogen gas adsorption (BET) study revealed Type III isotherms, signifying microporous and mesoporous features with maximum BET surface area of 24 m<sup>2</sup>/g, Langmuir surface area of 612 m<sup>2</sup>/g and varying pore sizes ranging between 8.48 and 10.13 nm. Low-pressure gas adsorption (LPGA) using CO<sub>2</sub> gas was used to evaluate the materials' adsorption capacity. Results showed that increasing the synthesis temperature to 125 °C increased the adsorption capacity to a maximum of 31 cm<sup>3</sup>/g. The SEM micrographs display diverse morphologies with irregular patterns and cloud-like structures across samples.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 1-9"},"PeriodicalIF":0.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144632056","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}
Pub Date : 2025-10-01Epub Date: 2025-08-22DOI: 10.1016/j.sajce.2025.08.012
Mrs.Cecilia M. Botha , Shawn C. Liebenberg , Frederik H. Conradie , Mr.Abraham F. van der Merwe
Statistical methods play a crucial role in the analysis and interpretation of complex data in chemical engineering research. However, parametric statistical approaches may not always suffice in addressing the intricacies of data analysis within design, process modelling and process development. This paper explores the application potential of less conventional statistical methods in the context of chemical engineering. The application potential of these methods will be demonstrated using recent findings from a study conducted on a low-flux flue gas desulphurisation circulating fluidised bed (FGD-CFB). We analysed the solids flux measurements in a novel, low-flux CFB system by using a less conventional statistical technique, the Bland-Altman method, and verifying the findings using the Kruskal-Wallis test. This statistical analysis validated a non-isokinetic solids sampling technique for low-flux dry and semi-dry FGD-CFBs. This case study demonstrates the applicability of this statistical method within chemical engineering, highlighting its potential beyond its traditional use in medical research. Importantly, the focus of this contribution lies not on the specific findings of the case study, but on the methodologies employed therein. This paper aims to be an educational piece to inform the chemical engineering researcher on how and why this less-used-within-engineering statistical method may be applied. It highlights the potential of utilising statistical approaches that are typically used outside the context of engineering in addressing practical engineering challenges. This paper emphasises the applicability of this statistical method in providing valuable insights into complex engineering systems. It is guided by a systematic inquiry aimed at assessing the statistical methods’ suitability for different types of data sets. By embracing this method, chemical engineers can potentially unlock new insights for research and development, facilitating innovation, sustainability, and advancement in the field.
{"title":"The potential of the Bland-Altman method in chemical engineering","authors":"Mrs.Cecilia M. Botha , Shawn C. Liebenberg , Frederik H. Conradie , Mr.Abraham F. van der Merwe","doi":"10.1016/j.sajce.2025.08.012","DOIUrl":"10.1016/j.sajce.2025.08.012","url":null,"abstract":"<div><div>Statistical methods play a crucial role in the analysis and interpretation of complex data in chemical engineering research. However, parametric statistical approaches may not always suffice in addressing the intricacies of data analysis within design, process modelling and process development. This paper explores the application potential of less conventional statistical methods in the context of chemical engineering. The application potential of these methods will be demonstrated using recent findings from a study conducted on a low-flux flue gas desulphurisation circulating fluidised bed (FGD-CFB). We analysed the solids flux measurements in a novel, low-flux CFB system by using a less conventional statistical technique, the Bland-Altman method, and verifying the findings using the Kruskal-Wallis test. This statistical analysis validated a non-isokinetic solids sampling technique for low-flux dry and semi-dry FGD-CFBs. This case study demonstrates the applicability of this statistical method within chemical engineering, highlighting its potential beyond its traditional use in medical research. Importantly, the focus of this contribution lies not on the specific findings of the case study, but on the methodologies employed therein. This paper aims to be an educational piece to inform the chemical engineering researcher on how and why this less-used-within-engineering statistical method may be applied. It highlights the potential of utilising statistical approaches that are typically used outside the context of engineering in addressing practical engineering challenges. This paper emphasises the applicability of this statistical method in providing valuable insights into complex engineering systems. It is guided by a systematic inquiry aimed at assessing the statistical methods’ suitability for different types of data sets. By embracing this method, chemical engineers can potentially unlock new insights for research and development, facilitating innovation, sustainability, and advancement in the field.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 348-356"},"PeriodicalIF":0.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144903079","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}
Pub Date : 2025-10-01Epub Date: 2025-07-15DOI: 10.1016/j.sajce.2025.07.006
M. Ananthkumar , K. M. Mini , P. Thilagavathy
The use of natural compounds derived from plant extracts offers an eco-friendly solution for preventing the corrosion of rebar in concrete structures. This study investigates the corrosion inhibition efficiency of Cassia fistula (CF) leaf extract on mild steel in NaCl-contaminated simulated concrete pore solution (SPS). The corrosion protection performance was evaluated using weight loss measurements, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). Surface analyses were conducted using scanning electron microscopy (SEM) and atomic force microscopy (AFM) to assess the protective film formation. The results revealed that at an optimum concentration of 5 % v/v CF extract, a maximum inhibition efficiency of 85.21 % (from weight loss) and 92.4 % (from PDP) was achieved, accompanied by a significant increase in charge transfer resistance (799 Ω·cm²). indicating strong barrier formation on the metal surface. SEM and AFM analyses demonstrated smoother and less corroded steel surfaces in the presence of CF extract. This work demonstrates the potential of Cassia fistula leaf extract as a sustainable and effective corrosion inhibitor for reinforced concrete structures, aligning with the demand for green and durable construction materials.
{"title":"Eco-friendly corrosion protection of steel in simulated concrete environments using cassia fistula leaf extract: Electrochemical and surface characterization study","authors":"M. Ananthkumar , K. M. Mini , P. Thilagavathy","doi":"10.1016/j.sajce.2025.07.006","DOIUrl":"10.1016/j.sajce.2025.07.006","url":null,"abstract":"<div><div>The use of natural compounds derived from plant extracts offers an eco-friendly solution for preventing the corrosion of rebar in concrete structures. This study investigates the corrosion inhibition efficiency of <em>Cassia fistula</em> (CF) leaf extract on mild steel in NaCl-contaminated simulated concrete pore solution (SPS). The corrosion protection performance was evaluated using weight loss measurements, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). Surface analyses were conducted using scanning electron microscopy (SEM) and atomic force microscopy (AFM) to assess the protective film formation. The results revealed that at an optimum concentration of 5 % v/v CF extract, a maximum inhibition efficiency of 85.21 % (from weight loss) and 92.4 % (from PDP) was achieved, accompanied by a significant increase in charge transfer resistance (799 Ω·cm²). indicating strong barrier formation on the metal surface. SEM and AFM analyses demonstrated smoother and less corroded steel surfaces in the presence of CF extract. This work demonstrates the potential of <em>Cassia fistula</em> leaf extract as a sustainable and effective corrosion inhibitor for reinforced concrete structures, aligning with the demand for green and durable construction materials.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 44-49"},"PeriodicalIF":0.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144655867","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}
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