Pub Date : 2025-09-10DOI: 10.1016/j.sajce.2025.09.006
Mihret Kendie, Bidir Kassaw, Tadesse Bizuayehu
The alarming escalation of multidrug-resistant bacteria represents a critical global health challenge, demanding innovative antimicrobial solutions. Silver manganese oxide (Ag–MnO) nanocomposites were biosynthesized from silver nitrate and manganese sulphate using an eco-friendly and cost-effective method, assisted by hydroalcoholic leaf extract of Rumex Nervosus Vahl. The successful synthesis of Ag-MnO nanocomposites was confirmed using spectroscopic (UV–Vis and FT–IR), structural (XRD), and thermal (TGA/DTA) analyses. The surface plasmon resonance peak observed at 402.89 nm from UV–Viss afirms the formation of Ag–MnO nanocomposites. In FT-IR spectral shift indicates the effective chelating ability of the plant extract for the synthesizing of Ag–MnO nanocomposites. XRD analysis revealed an average crystallite size of 29.73 nm, confirming the material’s nanoscale crystalline nature, and the TGA/DTA analysis confirmed that the synthesized nanocomposites were stable at high temperatures. The nanocomposites showed notable antibacterial activity, with a greater effect against Gram-negative than Gram-positive bacteria, as demonstrated by the disc diffusion method. These results indicate that Ag–MnO nanocomposites hold strong potential as alternative agents for combating drug-resistant infections, with promising applications in biomedical and pharmaceutical fields.
{"title":"Eco-friendly synthesis, characterization of silver-doped manganese oxide nanocomposites using Rumex Nervosus Vahl leaf extract and its antibacterial activity","authors":"Mihret Kendie, Bidir Kassaw, Tadesse Bizuayehu","doi":"10.1016/j.sajce.2025.09.006","DOIUrl":"10.1016/j.sajce.2025.09.006","url":null,"abstract":"<div><div>The alarming escalation of multidrug-resistant bacteria represents a critical global health challenge, demanding innovative antimicrobial solutions. Silver manganese oxide (Ag–MnO) nanocomposites were biosynthesized from silver nitrate and manganese sulphate using an eco-friendly and cost-effective method, assisted by hydroalcoholic leaf extract of <em>Rumex Nervosus Vahl</em>. The successful synthesis of Ag-MnO nanocomposites was confirmed using spectroscopic (UV–Vis and FT–IR), structural (XRD), and thermal (TGA/DTA) analyses. The surface plasmon resonance peak observed at 402.89 nm from UV–Viss afirms the formation of Ag–MnO nanocomposites. In FT-IR spectral shift indicates the effective chelating ability of the plant extract for the synthesizing of Ag–MnO nanocomposites. XRD analysis revealed an average crystallite size of 29.73 nm, confirming the material’s nanoscale crystalline nature, and the TGA/DTA analysis confirmed that the synthesized nanocomposites were stable at high temperatures. The nanocomposites showed notable antibacterial activity, with a greater effect against Gram-negative than Gram-positive bacteria, as demonstrated by the disc diffusion method. These results indicate that Ag–MnO nanocomposites hold strong potential as alternative agents for combating drug-resistant infections, with promising applications in biomedical and pharmaceutical fields.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 484-493"},"PeriodicalIF":0.0,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145118019","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 : 2025-09-10DOI: 10.1016/j.sajce.2025.09.001
Seyed Matin Malakouti, Mohammad Bagher Menhaj, Amir Abolfazl Suratgar
This study uses machine learning algorithms to predict energy consumption across the United States's critical sectors (commercial, residential, transportation, and industrial). The Ridge algorithm emerged as the most accurate and efficient in predicting energy consumption, outperforming other algorithms such as Lasso Regression, Elastic Net, Extra Tree, Random Forest, K Neighbors, and Orthogonal Matching Pursuit. The study employed data collection, feature engineering, model training, and evaluation based on metrics like MAPE, RMSLE, RMSE, MSE, and MAE, alongside speed evaluations. Key findings highlight the superior performance of the Ridge algorithm across residential, industrial, and commercial sectors in terms of accuracy (low MSE values) and computational efficiency. Additionally, the Orthogonal Matching Pursuit algorithm showed promise in predicting energy consumption in the transportation sector. These results provide valuable insights for energy management strategies, emphasizing the importance of accurate energy consumption predictions in effective power distribution and outage risk reduction.
{"title":"Efficiency and accuracy comparison of machine learning algorithms for predicting US energy consumption across sectors","authors":"Seyed Matin Malakouti, Mohammad Bagher Menhaj, Amir Abolfazl Suratgar","doi":"10.1016/j.sajce.2025.09.001","DOIUrl":"10.1016/j.sajce.2025.09.001","url":null,"abstract":"<div><div>This study uses machine learning algorithms to predict energy consumption across the United States's critical sectors (commercial, residential, transportation, and industrial). The Ridge algorithm emerged as the most accurate and efficient in predicting energy consumption, outperforming other algorithms such as Lasso Regression, Elastic Net, Extra Tree, Random Forest, K Neighbors, and Orthogonal Matching Pursuit. The study employed data collection, feature engineering, model training, and evaluation based on metrics like MAPE, RMSLE, RMSE, MSE, and MAE, alongside speed evaluations. Key findings highlight the superior performance of the Ridge algorithm across residential, industrial, and commercial sectors in terms of accuracy (low MSE values) and computational efficiency. Additionally, the Orthogonal Matching Pursuit algorithm showed promise in predicting energy consumption in the transportation sector. These results provide valuable insights for energy management strategies, emphasizing the importance of accurate energy consumption predictions in effective power distribution and outage risk reduction.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 424-440"},"PeriodicalIF":0.0,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095150","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}
The increasing demand for safer, more natural antimicrobial agents has driven interest in plant-derived essential oils as alternatives to synthetic preservatives. In this study, cinnamon essential oil nanoemulsions were successfully prepared using high-speed homogenization followed by ultrasonication method, with Tween-80 serving as a surfactant. The resulting nanoemulsions were characterized by dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), and UV–visible spectroscopy. The nanoemulsions exhibited droplet sizes below 22 nm, low polydispersity indices (PDI), and negative zeta potentials, indicating good stability. FTIR analysis confirmed the presence of characteristic functional groups, while UV–vis spectra revealed absorption peaks associated with cinnamaldehyde, the major component of the essential oil. Storage stability tests at 4 °C over seven days demonstrated minimal changes in droplet size, PDI, and zeta potential. Importantly, antifungal assays revealed that nanoemulsions containing 5–9 % cinnamon essential oil effectively inhibited the growth of Penicillium pinophilum, with inhibition zones up to 23.7 mm. These findings suggest that cinnamon essential oil nanoemulsions offer a promising, natural strategy for antifungal applications in food preservation and related industries.
{"title":"Formulation and characterization of ultrasound-assisted cinnamon essential oil nanoemulsions and its antifungal activity","authors":"Jia Zhenhua , Naris Barnthip , Pichet Limsuwan , Voranuch Thongpool","doi":"10.1016/j.sajce.2025.09.005","DOIUrl":"10.1016/j.sajce.2025.09.005","url":null,"abstract":"<div><div>The increasing demand for safer, more natural antimicrobial agents has driven interest in plant-derived essential oils as alternatives to synthetic preservatives. In this study, cinnamon essential oil nanoemulsions were successfully prepared using high-speed homogenization followed by ultrasonication method, with Tween-80 serving as a surfactant. The resulting nanoemulsions were characterized by dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), and UV–visible spectroscopy. The nanoemulsions exhibited droplet sizes below 22 nm, low polydispersity indices (PDI), and negative zeta potentials, indicating good stability. FTIR analysis confirmed the presence of characteristic functional groups, while UV–vis spectra revealed absorption peaks associated with cinnamaldehyde, the major component of the essential oil. Storage stability tests at 4 °C over seven days demonstrated minimal changes in droplet size, PDI, and zeta potential. Importantly, antifungal assays revealed that nanoemulsions containing 5–9 % cinnamon essential oil effectively inhibited the growth of <em>Penicillium pinophilum</em>, with inhibition zones up to 23.7 mm. These findings suggest that cinnamon essential oil nanoemulsions offer a promising, natural strategy for antifungal applications in food preservation and related industries.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 418-423"},"PeriodicalIF":0.0,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060334","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 : 2025-09-10DOI: 10.1016/j.sajce.2025.09.007
Atheel Alwash
The heterojunction photocatalyst of CuO/ZnO has attracted considerable interest due to its superior ability to degrade organic pollutants through photocatalytic processes. In this research, CuO/ZnO heterojunctions were successfully synthesized by thermal combustion technique. The structural, morphological, and optical characteristics of the resulting materials were extensively analyzed using various characterization methods. Diffraction studies confirmed the presence of both CuO and ZnO phases, with an average crystalline size of 29.625 nm. These findings were corroborated by TEM analysis, which also highlighted the particle size and geometric shape. BET analysis revealed a mesoporous structure with a surface area of 4.18 m²/g. The band gap energy of the catalyst was determined to be 1.48 eV, attributed to the interaction between copper and zinc oxides. The Photoluminescence (PL) indicates the reduction in PL intensity of CuO-ZnO/GA compared to ZnO/GA ascribed to the reduction in electron–hole Coulombic attraction. The photocatalytic efficiency of the CuO/ZnO heterojunction was assessed by its degradation of methylene blue (MB) dye, achieving 97% removal. This enhanced in catalytic efficiency was attributed to the effective separation of electron-hole pairs and the extended absorption range into the visible light spectrum.
{"title":"Green fabrication of p-n CuO/ZnO heterojunctions for efficient photocatalytic degradation of dyes","authors":"Atheel Alwash","doi":"10.1016/j.sajce.2025.09.007","DOIUrl":"10.1016/j.sajce.2025.09.007","url":null,"abstract":"<div><div>The heterojunction photocatalyst of CuO/ZnO has attracted considerable interest due to its superior ability to degrade organic pollutants through photocatalytic processes. In this research, CuO/ZnO heterojunctions were successfully synthesized by thermal combustion technique. The structural, morphological, and optical characteristics of the resulting materials were extensively analyzed using various characterization methods. Diffraction studies confirmed the presence of both CuO and ZnO phases, with an average crystalline size of 29.625 nm. These findings were corroborated by TEM analysis, which also highlighted the particle size and geometric shape. BET analysis revealed a mesoporous structure with a surface area of 4.18 m²/g. The band gap energy of the catalyst was determined to be 1.48 eV, attributed to the interaction between copper and zinc oxides. The Photoluminescence (PL) indicates the reduction in PL intensity of CuO-ZnO/GA compared to ZnO/GA ascribed to the reduction in electron–hole Coulombic attraction. The photocatalytic efficiency of the CuO/ZnO heterojunction was assessed by its degradation of methylene blue (MB) dye, achieving 97% removal. This enhanced in catalytic efficiency was attributed to the effective separation of electron-hole pairs and the extended absorption range into the visible light spectrum.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 441-450"},"PeriodicalIF":0.0,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095147","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 : 2025-09-10DOI: 10.1016/j.sajce.2025.09.004
Budi Istana , I Made Londen Batan , Sutikno , Ubaidillah , Iwan Yahya , Asranudin , Agus Wedi Pratama , Victor Feizal Knight , Mohd Nor Faiz Norrrahim
Oil palm frond (OPF) fibers offer a sustainable raw material for composite panels, yet their dimensional stability and durability remain challenging. This study evaluated the effect of alkali treatment duration (0, 60, and 180 min NaOH immersion) on the physical, mechanical, and acoustic properties of OPF-based composites. Thickness Swelling (TSw), Water Absorption (W-Abs), flexural and internal bonding (IB) strength, and sound absorption coefficient (SAC) were assessed. TSw increased significantly from 35.69 % in untreated panels to 73.74 % (+106.6 %) after 60 min and 102.63 % (+187.6 %) after 180 min, while W-Abs rose modestly (∼17 %). IB strength decreased progressively with longer treatment, indicating weakened fiber–matrix adhesion. In contrast, acoustic performance improved, particularly at mid-to-high frequencies, due to enhanced porosity and surface roughness. These findings show that alkali treatment improves acoustic absorption but compromises dimensional and mechanical stability. Moderate treatment or coupling with hydrophobic modification is recommended to balance performance and durability.
油棕叶（OPF）纤维为复合材料板提供了一种可持续的原材料，但其尺寸稳定性和耐用性仍然具有挑战性。本研究评估了碱处理时间（0,60和180 min NaOH浸泡）对opf基复合材料的物理、机械和声学性能的影响。评估厚度膨胀（TSw）、吸水率（W-Abs）、弯曲和内部结合强度（IB）和吸声系数（SAC）。TSw在未处理组从35.69%显著增加到60 min后的73.74%（+ 106.6%）和180 min后的102.63%(+ 187.6%)，而W-Abs则小幅上升（~ 17%）。随着处理时间的延长，IB强度逐渐下降，表明纤维基质粘附力减弱。相比之下，由于孔隙度和表面粗糙度的提高，声学性能得到了改善，特别是在中高频下。这些发现表明，碱处理改善了声吸收，但损害了尺寸和机械稳定性。建议适度处理或与疏水改性耦合以平衡性能和耐久性。
{"title":"Impact of alkali treatment on the mechanical, acoustic, and morphological characteristics of sustainable oil palm frond fiber composites","authors":"Budi Istana , I Made Londen Batan , Sutikno , Ubaidillah , Iwan Yahya , Asranudin , Agus Wedi Pratama , Victor Feizal Knight , Mohd Nor Faiz Norrrahim","doi":"10.1016/j.sajce.2025.09.004","DOIUrl":"10.1016/j.sajce.2025.09.004","url":null,"abstract":"<div><div>Oil palm frond (OPF) fibers offer a sustainable raw material for composite panels, yet their dimensional stability and durability remain challenging. This study evaluated the effect of alkali treatment duration (0, 60, and 180 min NaOH immersion) on the physical, mechanical, and acoustic properties of OPF-based composites. Thickness Swelling (TSw), Water Absorption (W-Abs), flexural and internal bonding (IB) strength, and sound absorption coefficient (SAC) were assessed. TSw increased significantly from 35.69 % in untreated panels to 73.74 % (+106.6 %) after 60 min and 102.63 % (+187.6 %) after 180 min, while W-Abs rose modestly (∼17 %). IB strength decreased progressively with longer treatment, indicating weakened fiber–matrix adhesion. In contrast, acoustic performance improved, particularly at mid-to-high frequencies, due to enhanced porosity and surface roughness. These findings show that alkali treatment improves acoustic absorption but compromises dimensional and mechanical stability. Moderate treatment or coupling with hydrophobic modification is recommended to balance performance and durability.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 475-483"},"PeriodicalIF":0.0,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095149","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 : 2025-09-08DOI: 10.1016/j.sajce.2025.09.002
Jeffrey K. Muriithi , Fabian Nachbur , Josephat K. Tanui , Godfrey K. Gakingo
To enhance the delivery of Fluid mMechanics, engineering instructors have found practical laboratory experiments to be a useful complementary tool. Various experimental methods have been adopted with recent interest being in the use of low-cost particle image velocimetry (PIV). This technique involves seeding of a flow with particles, recording the particles’ motion using low-cost components and thereafter analysing the generated images using open-source software to give velocity information. Low-cost PIV has been found to be feasible for educational demonstration purposes though the use of low-cost components (such as mobile phone cameras) has limited the applicability of the technique to slow flows. To overcome this limitation while keeping the noble idea of a low-cost particle velocimetry technique, this study proposes the use of low-cost particle streak velocimetry (PSV) instead. The PSV technique relies on a set up similar to that used for low-cost PIV. However, its analysis procedure requires only one image and the camera’s exposure time (or shutter speed) which can be readily controlled in low-cost cameras. In comparison, low-cost PIV requires two images and the timestep between the images which is fixed by the camera’s framerate (low-cost cameras have low framerates). This study therefore tests whether low-cost PSV technique can be used to attain higher velocities in comparison to low-cost PIV. The concept has been tested on an air jet produced from a laboratory-type Bunsen burner, with velocities in the order of 800 mm/s measured which were comparatively higher than those reported in low-cost PIV literature (250 mm/s). In addition, good accuracy was achieved by the method with the mean velocity measured to within 4 % of the theoretical value.
{"title":"Enhancing the delivery of Fluid Mechanics education through the use of low-cost phone-based particle streak velocimetry","authors":"Jeffrey K. Muriithi , Fabian Nachbur , Josephat K. Tanui , Godfrey K. Gakingo","doi":"10.1016/j.sajce.2025.09.002","DOIUrl":"10.1016/j.sajce.2025.09.002","url":null,"abstract":"<div><div>To enhance the delivery of Fluid mMechanics, engineering instructors have found practical laboratory experiments to be a useful complementary tool. Various experimental methods have been adopted with recent interest being in the use of low-cost particle image velocimetry (PIV). This technique involves seeding of a flow with particles, recording the particles’ motion using low-cost components and thereafter analysing the generated images using open-source software to give velocity information. Low-cost PIV has been found to be feasible for educational demonstration purposes though the use of low-cost components (such as mobile phone cameras) has limited the applicability of the technique to slow flows. To overcome this limitation while keeping the noble idea of a low-cost particle velocimetry technique, this study proposes the use of low-cost particle streak velocimetry (PSV) instead. The PSV technique relies on a set up similar to that used for low-cost PIV. However, its analysis procedure requires only one image and the camera’s exposure time (or shutter speed) which can be readily controlled in low-cost cameras. In comparison, low-cost PIV requires two images and the timestep between the images which is fixed by the camera’s framerate (low-cost cameras have low framerates). This study therefore tests whether low-cost PSV technique can be used to attain higher velocities in comparison to low-cost PIV. The concept has been tested on an air jet produced from a laboratory-type Bunsen burner, with velocities in the order of 800 mm/s measured which were comparatively higher than those reported in low-cost PIV literature (250 mm/s). In addition, good accuracy was achieved by the method with the mean velocity measured to within 4 % of the theoretical value.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 470-474"},"PeriodicalIF":0.0,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095148","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}
The development of eco-friendly and high-performance corrosion inhibitors is crucial to preventing the long-term degradation of low-carbon steel (LCS) in aggressive environments. Conventional inhibitors often suffer from toxicity and limited durability, prompting the need for sustainable alternatives. In this study, polylactic acid (PLA)/ZnO nanocomposites were fabricated via a spin-coating technique and evaluated as green corrosion protection systems for LCS immersed in 1 M HCl. The nanocomposite containing 0.05 g ZnO per 100 mL PLA exhibited the highest inhibition efficiency of 96.75 %, forming a compact and adherent barrier that suppressed both electrochemical reactions and chloride ion penetration. This optimized concentration uniquely provided the best balance between nanoparticle dispersion and coating integrity, preventing agglomeration while enhancing surface adsorption and barrier characteristics—advantages not previously achieved in similar PLA/ZnO systems. Unlike higher ZnO loadings that led to structural defects, the 0.05 g ZnO formulation ensured uniform particle distribution, optimal charge transfer resistance, and long-term film stability, as confirmed by EIS, SEM, FTIR, and quantum chemical calculations. This work not only introduces a biodegradable and scalable solution for corrosion mitigation but also establishes a mechanistic rationale for selecting optimal nanoparticle loading, thus advancing the design of sustainable corrosion-resistant coatings.
开发环保型和高性能的缓蚀剂对于防止低碳钢（LCS）在腐蚀性环境中长期降解至关重要。传统的抑制剂往往存在毒性和有限的耐久性，这促使人们需要可持续的替代品。本研究采用旋涂技术制备了聚乳酸(PLA)/ZnO纳米复合材料，并对其作为LCS浸在1 M HCl中的绿色防腐体系进行了评价。每100 mL PLA中含有0.05 g ZnO的纳米复合材料的抑制效率最高，达到96.75%，形成致密的粘附屏障，既抑制了电化学反应，又抑制了氯离子的渗透。这种优化的浓度独特地提供了纳米颗粒分散和涂层完整性之间的最佳平衡，在增强表面吸附和屏障特性的同时防止团聚，这是以前在类似的PLA/ZnO体系中没有实现的优势。通过EIS、SEM、FTIR和量子化学计算证实，与较高ZnO负载导致的结构缺陷不同，0.05 g ZnO配方确保了均匀的颗粒分布、最佳的电荷转移电阻和长期的薄膜稳定性。这项工作不仅介绍了一种可生物降解和可扩展的缓蚀解决方案，而且还建立了选择最佳纳米颗粒负载的机制原理，从而推进了可持续耐腐蚀涂层的设计。
{"title":"PLA/ZnO nanocomposites with 0.05 % w/v ZnO enhanced long-term corrosion inhibition of low carbon steel","authors":"Budi Mulyati , Femiana Gapsari , Saidun Fiddaroini , Masruroh , Akhmad Sabarudin","doi":"10.1016/j.sajce.2025.09.003","DOIUrl":"10.1016/j.sajce.2025.09.003","url":null,"abstract":"<div><div>The development of eco-friendly and high-performance corrosion inhibitors is crucial to preventing the long-term degradation of low-carbon steel (LCS) in aggressive environments. Conventional inhibitors often suffer from toxicity and limited durability, prompting the need for sustainable alternatives. In this study, polylactic acid (PLA)/ZnO nanocomposites were fabricated via a spin-coating technique and evaluated as green corrosion protection systems for LCS immersed in 1 M HCl. The nanocomposite containing 0.05 g ZnO per 100 mL PLA exhibited the highest inhibition efficiency of 96.75 %, forming a compact and adherent barrier that suppressed both electrochemical reactions and chloride ion penetration. This optimized concentration uniquely provided the best balance between nanoparticle dispersion and coating integrity, preventing agglomeration while enhancing surface adsorption and barrier characteristics—advantages not previously achieved in similar PLA/ZnO systems. Unlike higher ZnO loadings that led to structural defects, the 0.05 g ZnO formulation ensured uniform particle distribution, optimal charge transfer resistance, and long-term film stability, as confirmed by EIS, SEM, FTIR, and quantum chemical calculations. This work not only introduces a biodegradable and scalable solution for corrosion mitigation but also establishes a mechanistic rationale for selecting optimal nanoparticle loading, thus advancing the design of sustainable corrosion-resistant coatings.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 397-417"},"PeriodicalIF":0.0,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145044034","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 : 2025-08-30DOI: 10.1016/j.sajce.2025.08.016
E.L. Odekanle , O.S. Teniola , I.O. Olaoye , O.A. Falowo , J. Undiandeye
This study investigated the process kinetics of the anaerobic digestion of different wastes under mesophilic conditions. A slurry of cattle dung was anaerobically digested in fabricated 25-litre reactors for 24 days. The biogas volume, physicochemical, and microbial properties of the digesting slurry were determined every three days using standard procedures. Kinetic models based on the first-order, Monod, and Grau second-order expressions were employed to estimate the performance of the process. After the experiment, a cumulative 0.0265 m³ of biogas was produced, and significant variations in the physicochemical and microbial properties of the digestate were observed. The process kinetics of the digestion followed a first-order reaction with a rate constant of 0.0526 day-1 and 75.1 % COD removal efficiency. For the Monod model, the maximum rate of substrate utilization and saturation constant was found to be 0.1107 day-1 and 1326.34 mg/l respectively. Based on analytical parameter, this anaerobic digestion process followed both first-order kinetic and Monod models only, which shows that for maximum biogas production from animal waste, inoculation would be required.
研究了中温条件下不同废物厌氧消化的过程动力学。牛粪浆液在自制的25升反应器中厌氧消化24天。利用标准程序每三天测定一次沼液的沼气量、理化性质和微生物特性。采用基于一阶、Monod和Grau二阶表达式的动力学模型来估计该过程的性能。实验结束后，累计产生了0.0265 m³的沼气，并观察到消化液的理化和微生物特性发生了显著变化。消化过程动力学符合一级反应，速率常数为0.0526 d -1， COD去除率为75.1%。在Monod模型中，底物利用率和饱和常数的最大值分别为0.1107 day-1和1326.34 mg/l。根据分析参数，该厌氧消化过程仅符合一级动力学模型和Monod模型，这表明为了最大限度地利用动物粪便产生沼气，需要接种。
{"title":"Physicochemical characterization and kinetic study of anaerobic digestion of cattle dung in a semi-batch reactor","authors":"E.L. Odekanle , O.S. Teniola , I.O. Olaoye , O.A. Falowo , J. Undiandeye","doi":"10.1016/j.sajce.2025.08.016","DOIUrl":"10.1016/j.sajce.2025.08.016","url":null,"abstract":"<div><div>This study investigated the process kinetics of the anaerobic digestion of different wastes under mesophilic conditions. A slurry of cattle dung was anaerobically digested in fabricated 25-litre reactors for 24 days. The biogas volume, physicochemical, and microbial properties of the digesting slurry were determined every three days using standard procedures. Kinetic models based on the first-order, Monod, and Grau second-order expressions were employed to estimate the performance of the process. After the experiment, a cumulative 0.0265 m³ of biogas was produced, and significant variations in the physicochemical and microbial properties of the digestate were observed. The process kinetics of the digestion followed a first-order reaction with a rate constant of 0.0526 day<sup>-1</sup> and 75.1 % COD removal efficiency. For the Monod model, the maximum rate of substrate utilization and saturation constant was found to be 0.1107 day<sup>-1</sup> and 1326.34 mg/l respectively. Based on analytical parameter, this anaerobic digestion process followed both first-order kinetic and Monod models only, which shows that for maximum biogas production from animal waste, inoculation would be required.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 390-396"},"PeriodicalIF":0.0,"publicationDate":"2025-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144988483","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 : 2025-08-29DOI: 10.1016/j.sajce.2025.08.015
Mario Bonilla-Loor , Liceth Solórzano-Zambrano , Anderson Pazmiño , Diego Segovia-Cedeño , Johnny Delgado-Mera , Miguel Tuárez-Párraga , Ana Aguilar-Paredes , John Molina-Villamar
Predominant among the mangroves of the northern coast of Ecuador, the black mangrove (Avicennia germinans) has been traditionally used in medicine. This study focuses on its phytochemical characterization and antioxidant activity. Bark, leaves, seeds, and roots were washed, dried at 35 °C for 96 h until reaching a moisture content of 10 ± 2 %, and ground. Extracts were obtained by macerating the plant material (1:10 ratio) with sterile water or 96 % ethanol, followed by ultrasound-assisted extraction at 35 °C for 1 h and further maceration at 35 ± 1 °C for 24 h. Qualitative phytochemical screening identified secondary metabolites such as alkaloids, tannins, flavonoids, and saponins, while total phenol content was quantified using the Folin-Ciocalteu method. Antioxidant activity was evaluated using the DPPH and ABTS assays. Aqueous extracts showed higher phenol concentrations, with the bark extract containing 629.5 ± 10.44 mg GAE·g⁻¹. The roots exhibited the highest antioxidant activity, with 21,171.73 µmol Trolox equivalents g⁻¹ (DPPH) and 13,512.00 µmol Trolox equivalents g⁻¹ (ABTS). The antioxidant activity values exhibited statistically significant differences among the extracts and relative to other plant species. The differences in metabolite concentration and antioxidant activity among plant parts and solvents are attributed to physiological adaptation and selective mobility of compounds within the plant. These findings confirm that A. germinans is a valuable source of bioactive compounds with therapeutic and antioxidant properties, supporting its potential use in the development of antioxidant-based formulations. Moreover, these results provide key information for mangrove conservation and its potencial application in pharmaceutical, nutraceutical, and environmental sectors.
{"title":"Phytochemical characterization and antioxidant potential of black mangrove (Avicennia germinans L.) from the northern coast of Ecuador using aqueous and ethanolic extraction","authors":"Mario Bonilla-Loor , Liceth Solórzano-Zambrano , Anderson Pazmiño , Diego Segovia-Cedeño , Johnny Delgado-Mera , Miguel Tuárez-Párraga , Ana Aguilar-Paredes , John Molina-Villamar","doi":"10.1016/j.sajce.2025.08.015","DOIUrl":"10.1016/j.sajce.2025.08.015","url":null,"abstract":"<div><div>Predominant among the mangroves of the northern coast of Ecuador, the black mangrove (<em>Avicennia germinans)</em> has been traditionally used in medicine. This study focuses on its phytochemical characterization and antioxidant activity. Bark, leaves, seeds, and roots were washed, dried at 35 °C for 96 h until reaching a moisture content of 10 ± 2 %, and ground. Extracts were obtained by macerating the plant material (1:10 ratio) with sterile water or 96 % ethanol, followed by ultrasound-assisted extraction at 35 °C for 1 h and further maceration at 35 ± 1 °C for 24 h. Qualitative phytochemical screening identified secondary metabolites such as alkaloids, tannins, flavonoids, and saponins, while total phenol content was quantified using the Folin-Ciocalteu method. Antioxidant activity was evaluated using the DPPH and ABTS assays. Aqueous extracts showed higher phenol concentrations, with the bark extract containing 629.5 ± 10.44 mg GAE·g⁻¹. The roots exhibited the highest antioxidant activity, with 21,171.73 µmol Trolox equivalents g⁻¹ (DPPH) and 13,512.00 µmol Trolox equivalents g⁻¹ (ABTS). The antioxidant activity values exhibited statistically significant differences among the extracts and relative to other plant species. The differences in metabolite concentration and antioxidant activity among plant parts and solvents are attributed to physiological adaptation and selective mobility of compounds within the plant. These findings confirm that <em>A. germinans</em> is a valuable source of bioactive compounds with therapeutic and antioxidant properties, supporting its potential use in the development of antioxidant-based formulations. Moreover, these results provide key information for mangrove conservation and its potencial application in pharmaceutical, nutraceutical, and environmental sectors.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 451-460"},"PeriodicalIF":0.0,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095146","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 : 2025-08-27DOI: 10.1016/j.sajce.2025.08.014
Molly Katlo Keitemoge , Matthew Adah Onu , Olawumi Oluwafolakemi Sadare , Naadhira Seedat , Rishen Roopchund , Kapil Moothi
The growing occurrence of antibiotic residues in South African water systems poses serious environmental and public health risks, owing mostly to pharmaceutical discharge, agricultural runoff, and poor waste management. Conventional water treatment procedures frequently fail to properly remove these micropollutants, needing new predictive and analytical approaches. This review critically investigates the implementation of Artificial Neural Networks (ANN) and Adaptive Neuro-Fuzzy Inference System (ANFIS) models to forecast and optimize antibiotic removal from South African water bodies. To the best of our knowledge, little or no research compares the models' respective performances in the context of the urban water cycle in South Africa. Therefore, this review elaborates on some of the pharmaceuticals (such as diclofenac sodium and tetracycline) that have been studied, as well as the challenges associated with their removal. It also emphasizes studies on modeling and predicting pharmaceutical removal from wastewater using ANN and ANFIS models. Additionally, this review considered the comparisons between ANN and ANFIS models in predicting the removal of emerging contaminants, as well as the challenges and limitations associated with these modeling techniques. The studies established that AI models achieved higher R² and lower error metrics compared to classical statistical or isotherm models.
{"title":"Antibiotic removal in South African water using artificial neural networks and adaptive neuro-fuzzy inference system models: A review","authors":"Molly Katlo Keitemoge , Matthew Adah Onu , Olawumi Oluwafolakemi Sadare , Naadhira Seedat , Rishen Roopchund , Kapil Moothi","doi":"10.1016/j.sajce.2025.08.014","DOIUrl":"10.1016/j.sajce.2025.08.014","url":null,"abstract":"<div><div>The growing occurrence of antibiotic residues in South African water systems poses serious environmental and public health risks, owing mostly to pharmaceutical discharge, agricultural runoff, and poor waste management. Conventional water treatment procedures frequently fail to properly remove these micropollutants, needing new predictive and analytical approaches. This review critically investigates the implementation of Artificial Neural Networks (ANN) and Adaptive Neuro-Fuzzy Inference System (ANFIS) models to forecast and optimize antibiotic removal from South African water bodies. To the best of our knowledge, little or no research compares the models' respective performances in the context of the urban water cycle in South Africa. Therefore, this review elaborates on some of the pharmaceuticals (such as diclofenac sodium and tetracycline) that have been studied, as well as the challenges associated with their removal. It also emphasizes studies on modeling and predicting pharmaceutical removal from wastewater using ANN and ANFIS models. Additionally, this review considered the comparisons between ANN and ANFIS models in predicting the removal of emerging contaminants, as well as the challenges and limitations associated with these modeling techniques. The studies established that AI models achieved higher R² and lower error metrics compared to classical statistical or isotherm models.</div></div>","PeriodicalId":21926,"journal":{"name":"South African Journal of Chemical Engineering","volume":"54 ","pages":"Pages 371-389"},"PeriodicalIF":0.0,"publicationDate":"2025-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144932117","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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