Research Articles (Chemical Engineering)
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Item An overview of antifogging nanocoatings : recent developments and application(Elsevier, 2024-12) Sanni, Omotayo; Ren, Jianwei; Jen, Tien-Chien; jianwei.ren@up.ac.zaTransparent materials are essential to our daily lives. It's very well recognized that their use in windshields, cars, windows, mirrors, and eyewear makes our everyday tasks more comfortable. In addition to these, several other instances may be found in the culinary, medical, and solar industries, among other spheres of human endeavor. Unfortunately, under typical operating conditions, this material experiences fogging owing to the unavoidable condensation of water vapor on solid surface. Researchers are becoming more and more interested in antifogging nano-coatings with remarkable water repellence as a result of the growth of the coating industries and material engineering. Numerous compounds have been created by researchers thus far to prepare antifogging films. There have been reports on the mechanisms and guidelines for the creation of these agents by various technologies as a result of the core requirements of various fields. We present the latest developments in antifogging nanocoatings and antifogging performance test procedures in this review. Additionally, there has been a focus on offering understanding of the latest advancement in superhydrophobic coating through the application of nanotechnology. According to the literature, the reported antifogging films do not show sufficient results and continue to pose a practical issue that requires real-world application. As a result, antifogging techniques need to be improved further.Item Synthesis and evaluation of 3D nitrogen doped reduced graphene oxide (3D N@rGO) macrostructure for boosted solar driven interfacial desalination of saline water(Wiley, 2025-04) Bezza, Fisseha Andualem; Iwarere, Samuel Ayodele; Tichapondwa, Shepherd Masimba; Brink, Hendrik Gideon; Daramola, Michael Olawale; Chirwa, Evans M.N.; evans.chirwa@up.ac.zaPlease read abstract in the article.Item MIL-53(Al)-MOF sorbents in dispersive micro-solid phase extraction of penicillins from water(Elsevier, 2025-08) Skans, Inga; Dyosiba, Xoliswa Lindokuhle; Mnguni, Mthokozisi; Nomngongo, Philiswa NosizoPenicillin is an antibiotic that presents serious environmental risks because of its extensive use and ends up in our water bodies. This work presents the development and application of a dispersive micro-solid phase extraction (D-µ-SPE) procedure utilising the metal-organic framework MIL-53(Al) as a suitable adsorbent for preconcentration of piperacillin (PIP) and penicillin V (PNV) from water. The prepared MIL-53(Al)-MOF was characterised using various characterisation techniques. Following the extraction and preconcentration processes, a high-performance liquid chromatography-diode array detector (HPLC-DAD) was employed to separate and quantify PIP and PNV. The fractional factorial design (FrFD) and Box-Behnken design (BBD) were utilised to investigate parameters influencing the d-μ-SPE method for PIP and PNV. The maximum percentage recoveries were obtained under the following conditions: 5.5, 50 mg, 17.5 min, 1000 µL, and 10 min for pH, mass of adsorbent extraction time, eluent volume, and desorption time, respectively. High adsorption capacities for PIP (175 mg/g) and (217 mg/g) were achieved. The highest adsorption affinity toward zwitterionic analytes and quick kinetics of the adsorbent made the d-μ-SPE effective in extracting target analytes from various water matrices. The remarkable performance was attributed to electrostatic, hydrogen bonding, π–π and hydrophobic interactions. The pseudo-send order kinetics and Langmuir models described the adsorption data well. Under optimum conditions, the relatively low detection limits of 0.10–0.18 µg/L and wide linear range of 0.3–800 µg/L validated the effectiveness of the developed d-μ-SPE method. Applying the established d-µ-SPE/HPLC-DAD method to real water analysis verified its applicability and feasibility. In wastewater samples, PIP and PNV were found in the ranges of 0.71–1.12 µg/L for influent and 0.32–0.45 µg/L for effluent. PIP and PNV spike recoveries ranged from 91.7 % to 99.1 % and 93.2 % to 98.1 %, respectively, while the method's intraday and interday precision was <5 %. This work illustrates that the d-μ-SPE, in tandem with MIL-53(Al)-MOF, offers several advantages, including simplicity, rapidity and low solvent consumption for the recovery of penicillin from contaminated water sources. HIGHLIGHTS • MIL-53(Al)-MOF with attractive functional groups was successfully synthesized following a solvothermal techniques. • The prepared MIL-53(Al)-MOF has large adsorption capacities for piperacillin (175 mg/g) and penicillin V (217 mg/g). • The MIL-53(Al)-MOF/D-μ-SPE of piperacillin and penicillin V achieved high % recoveries with a range of 91–99 from environmental water and wastewater.Item Radioactivity distribution in soil, rock and tailings at the Geita Gold Mine in Tanzania(Elsevier, 2025-06) Mwimanzi, Jerome M.; Haneklaus, Nils H.; Bituh, Tomislav; Brink, Hendrik Gideon; Kiegiel, Katarzyna; Lolila, Farida; Marwa, Janeth J.; Rwiza, Mwemezi J.; Mtei, Kelvin M.Please read abstract in the article.Item Carbon nanofibers surface-exposed with highly active Ag nanoparticles for enhanced interfacial dynamics of lithium metal anodes(Wiley, 2025-06) Huang, Aoming; Huang, Hongjiao; Li, Shuo; Pan, Xiansong; Sun, Shichao; Su, Xueming; Geng, Hongbo; Li, Linlin; Maximov, Maxim; Ren, Jianwei; Peng, ShengjieLithium metal anodes (LMAs) are widely regarded as a crucial component for the next generation of high-energy-density lithium batteries. The extended pathways for lithium ion diffusion exacerbate concentration polarization, leading to dendrite growth in LMAs. Here, carbon nanofibers with surface-exposed high-activity silver nanoparticles (Ag@CNF) are achieved through the combination of electrospinning and ion exchange techniques, enhancing the interfacial dynamics during lithium storage. Compared to electrodes with encapsulated active sites, the self-supported and binder-free Ag@CNF significantly shortens lithium ion diffusion pathways, reduces nucleation overpotential, and promotes uniform ion diffusion and deposition. Furthermore, this unique structure induces a thinner solid electrolyte interphase (SEI) layer, and greatly reduces the apparent activation energy for charge transfer. Ag@CNF not only enhances atomic utilization efficiency of active centers but also optimizes performance in lithium metal batteries. Notably, assembled full cells demonstrate an excellent retention rate of 90% after 300 cycles at a high capacity of 1.5 mAh cm−2 and a low N/P ratio of 2.Item Enhanced photocatalytic efficiency of a novel GO/Bi2SO5/AgBr ternary heterojunction for the degradation of tetracycline and rhodamine B(Elsevier, 2025-06) Oluwole, Adewunmi Olufemi; Yusuf, Tunde Lewis; Tichapondwa, Shepherd Masimba; Daramola, Michael Olawale; Iwarere, Samuel Ayodele; samuel.iwarere@up.ac.zaPlease read abstract in the article.Item Preparation of hydrophilic PVDF membrane via blending with Fe3O4 nanoparticles and PVA for improved membrane performance in BTEX removal from wastewater(Elsevier, 2025-06) Enemuo, Ngozi; Richards, Heidi; Daramola, Michael OlawalePlease read abstract in the article.Item Novel BiOIO3/Bi12O17Cl2 heterostructure for improved photocatalytic degradation of dye pollutants under low energy visible light irradiation(Elsevier, 2025-03) Ogbeifun, Osemeikhian; Tichapondwa, Shepherd Masimba; Chirwa, Evans M.N.Please read abstract in the article.Item Design and fabrication of porous three‐dimensional Ag-doped reduced graphene oxide (3D Ag@rGO) composite for interfacial solar desalination(Nature Research, 2024-06-14) Bezza, Fisseha Andualem; Iwarere, Samuel Ayodele; Brink, Hendrik Gideon; Chirwa, Evans M.N.; evans.chirwa@up.ac.zaSolar-driven interfacial desalination technology has shown great promise in tackling the urgent global water scarcity crisis due to its ability to localize heat and its high solar-to-thermal energy conversion efficiency. For the realization of sustainable saline water desalination, the exploration of novel photothermal materials with higher water vapor generation and photothermal conversion efficiency is indispensable. In the current study, a novel 3D interconnected monolithic Ag-doped rGO network was synthesized for efficient photothermal application. The Ultraviolet–Visible-Near Infrared (UV–Vis-NIR) and FTIR analyses demonstrated that the controlled hydrothermal reduction of GO enabled the restoration of the conjugated sp2 bonded carbon network and the subsequent electrical and thermal conductivity through a significant reduction of oxygen-containing functional groups while maintaining the hydrophilicity of the composite photothermal material. In the solar simulated interfacial desalination study conducted using 3.5 wt.% saline water, the average surface temperatures of the 3D material increased from 27.1 to 54.7 °C in an hour, achieving an average net dark-excluded evaporation rate of 1.40 kg m−2 h−1 and a photothermal conversion efficiency of ~ 97.54% under 1 sun solar irradiance. In the outdoor real-world application test carried out, the surface temperature of the 3D solar evaporator reached up to 60 °C and achieved a net water evaporation rate of 1.50 kg m−2 h−1 under actual solar irradiation. The 3D interwoven porous hierarchical evaporator displayed no salt precipitation over the 54-h period monitored, demonstrating the promising salt rejection and real-world application potential for efficient desalination of saline water.Item Insights into the degradation of carbamazepine using a continuous-flow non-thermal plasma : kinetics and comparison with UV-based systems(Royal Society of Chemistry, 2025-06) Babalola, Samuel Olatunde; Daramola, Michael Olawale; Iwarere, Samuel Ayodele; samuel.iwarere@up.ac.zaPlease read abstract in the article.Item Fabrication of BiVO4/Ag2CrO4 heterojunction composites modified with graphene oxide for enhanced photoelectrochemical and photocatalytic performance(Royal Society of Chemistry, 2024-11) Oluwole, Adewunmi Olufemi; Yusuf, Tunde Lewis; Tichapondwa, Shepherd Masimba; Daramola, Michael Olawale; Iwarere, Samuel Ayodele; samuel.iwarere@up.ac.zaPlease read abstract in the article.Item Removal of tobacco specific carcinogenic nitrosamines in mainstream cigarette smoke and aqueous solution-a review(American Chemical Society, 2025-05) Setshedi, Katlego Z.; Maity, Arjun; Nyakale, Atlegang; Ramahlare, Sebasa; Chauke, Vongani P.; Nkomzwayo, Thulisile; Mandiwana, Vusani; Ray, Suprakas Sinha; Hlekelele, LeratoTobacco-specific N-nitrosamines (TSNAs), which are associated with several cancers, are formed during the processing of tobacco alkaloids. Since tobacco smoking poses serious health risks, scientists, governments, and health regulators globally have denounced it and categorized its constituents according to their carcinogenicity. Tobacco smoke investigations are guided by standardized methods (ISO). With the help of standardized smoke-generating machines, precise quantification of TSNAs and other smoke constituents is now possible thanks to advancements in analytical techniques. This information supports initiatives to reduce the amount of TSNAs that smoking exposes people to. This review covers the occurrence, formation pathways, precursors, and control strategies through removal technologies, providing thorough analysis of the state of science today regarding TSNAs. The adsorption characteristics of different materials as possible filter additives or modifiers are critically discussed, emphasizing important elements like porosity, layering, acidity/alkalinity, and surface area that affect their performance for capturing TSNAs from smoke. While scientific understanding of these areas is still evolving, this review intends to provide for the first time research progress on the adsorption properties of various materials, including zeolites, silica, few-layer black phosphorus, metal–organic frameworks, and molecularly imprinted polymers, among others, for reducing TSNAs present in both cigarette smoke and aqueous solutions.Item The influence of gold nanoparticles addition on sugarcane leaves-derived silica xerogel catalyst for the production of biodiesel(MDPI, 2025-02) Maseko, Ncamisile Nondumiso; Enke, Dirk; Owolawi, Pius Adewale; Iwarere, Samuel Ayodele; Oluwafemi, Oluwatobi Samuel; Pocock, Jonathan; samuel.iwarere@up.ac.zaBiodiesel was produced via transesterification of canola oil in the presence of a silica xerogel catalyst with deposited gold nanoparticles. The silica-gold catalyst was produced in situ, where gold metal was added to a sodium silicate solution; subsequently, gold nanoparticles were synthesised within the solution. The sodium silicate-gold nanoparticles solution was then turned into a silica-gold gel at pH 8.7 and later dried to form silica-gold nanoparticles xerogel. The produced silica-gold nanoparticles xerogel was characterised by X-ray diffraction (XRD), X-ray fluorescence (XRF), transition electron microscopy (TEM), and nitrogen physisorption. The gel had a silica content of 91.6 wt% and a sodium content of 6.4 wt%, with the added gold content being 99.5% retained. The biodiesel produced in the presence of silica-gold nanoparticles xerogel was characterised by gas chromatography-mass spectroscopy (GC-MS) and its physical properties, such as density, kinematic viscosity, flash point, pour point, and cloud point, were also determined. The silica-gold nanoparticles xerogel catalyst remained solid throughout its usage without leaching into the reaction medium. The produced biodiesel contained mostly monounsaturated fatty acid methyl esters and had a yield of 99.2% at optimum reaction conditions.Item Evaluation of the performance of Fe3O4-NPs/PVDF nanocomposite membrane for removal of BTEX from contaminated water(Elsevier, 2024-03-25) Enemuo, Ngozi; Richards, Heidi; Daramola, Michael Olawale; michael.daramola@up.ac.zaWith the increase in reported cases of toxic organic contaminants such as b in the aquatic environment, membrane technology offers a viable option for removing BTEX from wastewater. However, hydrophilic modification of the membranes is vital to reduce the rapid accumulation of the BTEX organic contaminants and maintain improved membrane performance in BTEX removal. In this study, biogenically-synthesized Fe3O4-NPs were embedded into a PVDF membrane to endow the membrane with hydrophilicity, which necessitates the reduction in BTEX accumulation on the membrane, consequently maintaining improved membrane performance towards BTEX removal. Different Fe3O4-NPs loadings (0 wt% to 5 wt%) were used for the PVDF modification to establish the optimum blending amount of the Fe3O4-NPs required to achieve the most effective membrane. The water contact angle was reduced from 84.2° (pristine PVDF) to 52° for the membrane modified with 1 wt% of the Fe3O4-NPs. Other membrane features such as porosity, surface roughness, and mechanical strength were also enhanced. Performance evaluation of the membranes revealed that the flux and BTEX rejection of the Fe3O4-NPs/PVDF membrane were improved. The antifouling test results showed a reduction in the total fouling from 52.1 % (pristine membrane) to 36.3 % for the membrane modified with 1 wt% of the Fe3O4-NPs. Our findings provide a strategy utilizing biogenically synthesized Fe3O4-NPs to enhance PVDF membranes' performance for removing BTEX from wastewater.Item Synthesis and dye adsorption dynamics of chitosan-polyvinylpolypyrrolidone (PVPP) composite(MDPI, 2024-09-10) Kyomuhimbo, Hilda Dinah; McHunu, Wandile; Arnold, Marco; Feleni, Usisipho; Haneklaus, Nils H.; Brink, Hendrik Gideon; deon.brink@up.ac.zaOne major environmental issue responsible for water pollution is the presence of dyes in the aquatic environment as a result of human activity, particularly the textile industry. Chitosan–Polyvinylpolypyrrolidone (PVPP) polymer composite beads were synthesized and explored for the adsorption of dyes (Bismarck brown (BB), orange G (OG), brilliant blue G (BBG), and indigo carmine (IC)) from dye solution. The CS-PVPP beads demonstrated high removal efficiency of BB (87%), OG (58%), BBG (42%), and IC (49%). The beads demonstrated a reasonable surface area of 2.203 m2/g and were negatively charged in the applicable operating pH ranges. TGA analysis showed that the polymer composite can withstand decomposition up to 400 °C, proving high stability in harsh conditions. FTIR analysis highlighted the presence of N-H amine, O-H alcohol, and S=O sulfo groups responsible for electrostatic interaction and hydrogen bonding with the dye molecules. A shift in the FTIR bands was observed on N-H and C-N stretching for the beads after dye adsorption, implying that adsorption was facilitated by hydrogen bonding and Van der Waals forces of attraction between the hydroxyl, amine, and carbonyl groups on the surface of the beads and the dye molecules. An increase in pH increased the adsorption capacity of the beads for BB while decreasing OG, BBG, and IC due to their cationic and anionic nature, respectively. While an increase in temperature did not affect the adsorption capacity of OG and BBG, it significantly improved the removal of BB and IC from the dye solution and the adsorption was thermodynamically favoured, as demonstrated by the negative Gibbs free energy at all temperatures. Adsorption of dye mixtures followed the characteristic adsorption nature of the individual dyes. The beads show great potential for applications in the treatment of dye wastewater.Item A review of weathering studies in plastics and biocomposites — effects on mechanical properties and emissions of volatile organic compounds (VOCs)(MDPI, 2024-04-16) Nzimande, Monwabisi Cyril; Mtibe, Asanda; Tichapondwa, Shepherd Masimba; John, Maya Jacob; shepherd.tichapondwa@up.ac.zaPolymeric materials undergo degradation when exposed to outdoor conditions due to the synergistic effects of sunlight, air, heat, and moisture. The degradation can lead to a decline in mechanical properties, fading, surface cracking, and haziness, attributed to the cleavage of the polymer chains and oxidation reactions. Accelerated weathering testing is a useful technique to evaluate the comparative photodegradation of materials within a reasonable timeframe. This review gives an overview of the different degradation mechanisms occurring in conventional plastics and bio-based materials. Case studies on accelerated weathering and its effect on the mechanical properties of conventional plastics and biocomposites are discussed. Different techniques for analysing volatile organic emissions (VOCs) have been summarized and studies highlighting the characterization of VOCs from aged plastics and biocomposites after aging have been cited.Item Untreated mining influenced water sludge (MIWS) for lead adsorption : modelling mass transfer effects(Italian Association of Chemical Engineering, 2024-12-30) Nchabeleng, Nokuthula; Brink, Hendrik Gideon; deon.brink@up.ac.zaContamination of water sources by heavy metals, such as lead, presents a significant environmental challenge. This study explored the kinetics of adsorption using a novel industrial waste by-product, mining influenced water sludge (MIWS), for the adsorption of lead in aqueous solutions. By varying agitation speeds – 150, 200 and 250 rpm – and average particle diameters – 1, 2 and 3 mm – the impact of external mass transfer effects and internal mass transfer effects was studied. It was observed that varying average adsorbent particle diameters had an impact on the adsorption kinetics, particularly regarding the time required to achieve equilibrium and maximum Pb(II) removal efficiency. At set conditions – same initial Pb(II) concentration, temperature, adsorbent dosage, and adsorbate solution pH – adsorption kinetics were notably faster for 1 mm adsorbate particles compared to 3 mm particles, requiring only half the time to reach equilibrium. The longer contact time required to reach equilibrium indicates the impact of internal mass transfer effects. Crank’s mass transfer model was used to quantify the effective diffusivity, providing operational parameters required for continuous process design. This research offers a sustainable remediation option by valorising an untreated waste sludge that can ideally be utilised in continuous flow processes, contributing to environmentally sound water treatment practices by lowering production energy requirements and reducing emissions.Item A brief overview of hydrogen production and storage(Elsevier, 2025-07) Sanni, Omotayo; Dyosiba, Xoliswa Lindokuhle; Ren, Jianwei; jianwei.ren@up.ac.zaGiven that the demand for hydrogen is predicted to grow by around eight times by 2050 compared to 2020, a number of factors may make it difficult to implement hydrogen applications successfully. Although storing hydrogen is still a major problem, it is seen to be one of the most promising alternative fuels replacing current fossil fuels. Technologies for hydrogen generation have emerged as a key component of the energy mix in a society that seeks to replace fossil fuels in order to reduce greenhouse gas emissions and address other environmental issues. Hydrogen is a clean "green" fuel of interest that can help achieve aggressive goals for reducing greenhouse gas emissions between 2035 and 2050. Currently used in industrial application, hydrogen compression and liquefaction are energy-intensive processes because they require low temperature (253 °C) and high pressure (30–70 MPa). Since chemical hydrogen storage allows for the safe storage of hydrogen-rich molecules in ambient settings, it is a possible substitute. Even though there are several molecules that are thought to be hydrogen transporters, some of them lackviable prospects for widespread commercialization. The present status of development of important areas of hydrogen production and storage technologies is reviewed, along with the advantages and disadvantages of each technique in relation to cost, efficiency, safety, and storage capacity. The safety implications of different H2 storage methods have received particular attention because safety issues are one of the main obstacles to the widespread use of H2 as a fuel source. This study also identifies the main obstacles and possibilities that the commercialization and development of hydrogen storage technology must overcome, such as the requirement for better materials, better system integration, and greater acceptability and awareness. From the reviewed literature, we have learned that when the challenges and constraints that are involved with the storage and production of hydrogen are adequately addressed, hydrogen will emerge as the first reliable source of energy. Secondly, thorough research on correct hydrogen processing designs will give an indication on the correct costing of these systems thus aiding in the minimization of operational and maintenance expenditures. Lastly, suggestions for further study and advancement with emphasis on bringing these technologies closer to commercial feasibility are reported. Therefore, policymakers, researchers, and scientists could utilize this review as a roadmap to help shape the future of hydrogen.Item Perspective on metal-organic frameworks-based atmospheric water harvesting systems towards universal adoption(Elsevier, 2025-08) Manyimo, Tonderai Leeroy; Ren, Jianwei; Wang, Hui; Peng, Shengjie; jianwei.ren@up.ac.zaClimate change and the unequal distribution of freshwater resources are contributing factors to the global water crisis. Metal-organic frameworks (MOFs) have become a viable material for atmospheric water harvesting (AWH) due to their function in low relative humidity (RH) conditions. Their potential in dry conditions is demonstrated by MOF-801's up to 0.3 L/kg MOF/day and MOF-303's 0.7–1 liter/kg MOF/day. MOFs' high porosity, adjustable adsorption characteristics, and reduced regeneration temperatures have made them stand out as better alternatives. In this review, MIL-101(Cr), MOF-801, and MOF-303 are recommended as appropriate for AWH applications due to their promising water adsorption capabilities. Studies have shown that MIL-101(Cr) can outperform conventional desiccants with a water uptake of up to 1.5 g/g. It is also discussed that MOFs are successful in arid areas where traditional methods are ineffective due to their exceptional selectivity for water adsorption, even in low-humidity conditions. In order to evaluate the most recent developments in MOF-based AWH technologies, this review compared their performance to that of current AWH techniques. Although the production of MOFs is still expensive, economic feasibility studies show that improvements in scalable synthesis techniques, such as green solvent-assisted fabrication, could drastically lower manufacturing costs. With current research concentrating on enhancing material stability to extend operational lifespans, MOFs' long-term viability is also greatly influenced by their durability and recyclability. Furthermore, total efficiency may be increased by hybrid AWH systems that combine MOFs with other adsorption materials, such as hydrogels. In this review, recent developments in MOF-based AWH systems are studied, with an emphasis on material characteristics, system performance, and large-scale viability.Item Conversion–lithiophilicity hosts toward long-term and high-energy-density lithium metal batteries(Wiley, 2025-05) Huang, Aoming; Huang, Hongjiao; Li, Shaoxiong; Pan, Xiansong; Wang, Ai-Yin; Chen, Han-Yi; Wang, Tao; Li, Linlin; Maximov, Maxim; Ren, Jianwei; Wu, Yuping; Peng, ShengjiePlease read abstract in the article.