Luke Chimuka

Luke Chimuka
University of the Witwatersrand | wits · School of Chemistry

PhD

About

210
Publications
74,639
Reads
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4,872
Citations
Citations since 2017
91 Research Items
3467 Citations
20172018201920202021202220230200400600800
20172018201920202021202220230200400600800
20172018201920202021202220230200400600800
20172018201920202021202220230200400600800
Additional affiliations
March 2006 - present
University of the Witwatersrand
Position
  • Professor (Full)

Publications

Publications (210)
Article
Acid mine drainage (AMD) has been a source of environmental contamination in many parts of the world. This is because many countries depend on mining as a source of revenue. However, waste tailing dumps often leach out toxic waste with high levels of metal ions and flow downstream to dams and rivers. The current remediation methods (passive and act...
Article
Full-text available
This work aimed at optimizing the QuEChERS method with PSA and then comparing it with Moringa Oleifera seed protein as a clean-up sorbent for the extraction of endocrine-disrupting chemicals. The response surface methodology approach was used in the optimization. A design of experiment (DoE) was used to investigate the effect of the sample mass (0....
Article
Plastic microbeads are inevitably released into the aqueous environment and easily enriched in wastewater treatment processes. They are commonly used in personal care and cosmetic products as abrasive agents. Different countries have imposed regulations on the use or incorporation of microbeads in personal care products, but these are not fully eli...
Article
The present study highlights the synthesis of a polypyrrole (Ppy) composite based on Macadamia nutshells (AMN) and binary metal oxides (Mn-Cu oxide) for the selective removal of Cr(VI) from aqueous solution. Ppy/AMN-Mn-Cu oxide nanocomposite was synthesized via in-situ oxidative polymerization of pyrrole monomer using FeCl3 as an oxidant in the pre...
Article
In this work, we demonstrate the development, evaluation and pre-liminary application of a novel passive sampler for monitoring of selected pharmaceuticals in environmental waters. The samplers were calibrated in laboratory-based experiments to obtain sampling rates (Rs) for carbamazepine, methocarbamol, etilefrine, venlafaxine and nevirapine. Pass...
Article
Fish inhabiting freshwater environments are susceptible to the ingestion of microplastics (MPs). Knowledge regarding MPs in freshwater fish in South Africa is very limited. In this study, the uptake of MPs by common carp (Cyprinus carpio) in the Vaal River in South Africa was assessed. MPs were detected in all of the twenty-six fish examined, 682 p...
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Full-text available
The scope of this study was to synthesise and characterise the multi-template molecularly imprinted polymer (MIP) and to use target compounds, naproxen, ibuprofen, diclofenac, fenoprofen and gemfibrozil as templates so as to achieve all maximum extraction efficiency for all compounds. These compounds are a class of nonsteroidal anti-inflammatory dr...
Chapter
Contamination of freshwater by pharmaceuticals and personal care products (PPCPs) in developing countries
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Most pollutant compounds exist as mixtures in the environment. In this regard, one of the 12 principles of green analytical chemistry emphasizes the need for methods that allow for analysis of multiple compounds versus those that analyze a single analyte at a time. In this work, we present a molecularly imprinted polymer (MIP) synthesized for the s...
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A survey of bioavailable polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like PCBs (dl-PCBs), and polybrominated biphenyls (PBBs) from ambient air, water and sediment was performed in the Hartbeespoort Dam area in South Africa, a region where data on highly toxic Stockholm Convention persistent organic pollu...
Article
Membrane protected extraction is an ongoing innovation for isolation and pre-concentration of analytes from complex samples. The extraction process, clean-up and pre-concentration of analytes occur in a single step. The inclusion of solid sorbents such as molecularly imprinted polymers (MIPs) after membrane extraction ensures that selective double...
Article
Full-text available
Moringa Oleifera commonly known as miracle tree, is widely distributed in tropical and subtropical regions. It is used in traditional medicine to treat several diseases such as diabetes, hypertension, cancer, and other infections. In order to optimize the time of harvesting Moringa plant leaves, it is important to understand how various environment...
Article
Magnetic solid phase extraction (MSPE) of pesticide residues in complex matrices is increasingly becoming popular. This can be attributed to the emergence of sorbents such as metal organic frameworks (MOFs), with high adsorption capacities and that can be easily fabricated with magnetic nanoparticles. Different types of magnetic MOFs have been used...
Article
In spite of recent reports on the presence of pharmaceuticals in African water bodies, their prevalence is still not sufficiently quantified. This is because the reports are still few with major focus on a limited number of pharmaceuticals. In this study, the suspect screening of 92 compounds (mainly pharmaceuticals and their transformation product...
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Full-text available
Phosphorus removal from effluents is vital to avoid eutrophication. The subject study presents the development and performance of poly(phenylenediamine) isometric adsorbents produced through oxidation using (NH4)2S2O8 and K2Cr2O7 oxidants. K2Cr2O7 synthesized polymers showed better adsorption capacities. The presence of Cr Lewis acid on the surface...
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A flexible composite adsorbent combination of polypyrrole and montmorillonite clay (PPy-MMT) has been prepared by in situ oxidative polymerization method. This well-achieved adsorbent has amphoteric characteristics and has been explored in many adsorption processes related to heavy metals removal, more especially Cr(VI) from the water phase. Howeve...
Article
This review reports on the increasing interest in technical designs, calibration, and application of PIM-based devices in sample pre-treatment and passive sampling in environmental water monitoring from 2010 to 2021. With regards to passive sampling, devices are calibrated in a laboratory setup using either a dip-in or flow-through approach before...
Article
This work demonstrates development and evaluation of a two-way technique based on the combination of membrane assisted solvent extraction and a molecularly imprinted polymer (MASE-MIP) for selective and efficient extraction of five selected pharmaceuticals belonging to five different therapeutic classes. The pharmaceuticals were extracted from surf...
Article
Sorptive pre-concentration of pesticide residues in food and environmental samples is increasingly gaining momentum. This can be attributed to fact that most sorptive extraction techniques are solvent-free as well as the availability of emerging sorbents with relatively high adsorption capacities. Metal organic frameworks (MOFs) are among the emerg...
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Full-text available
One of the major concerns in the consumption of antibiotics is the discovery of antibacterial resistant genes due to prolonged exposure which makes their presence in environmental samples a priority. In this study, we screened 52 antibiotics along a South African stream polluted with wastewater effluents and municipal dumpsite leachates. Of these a...
Article
Regular monitoring of the chemical status of water bodies remains crucial in countries where data on chemical fingerprints that can assist in environmental policy is still limited. The current study focused on the concentrations of 14 metals and their sources in two important South African rivers that pass through various rural areas and two semi-u...
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Full-text available
Isolation of the therapeutic cannabinoid compounds from Cannabis Sativa L. (C. Sativa) is important for the development of cannabis-based pharmaceuticals for cancer treatment, among other ailments. The main pharmacological cannabinoids are THC and CBD. However, THC also induces undesirable psychoactive effects. The decarboxylation process converts...
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The aim of this study was to develop and validate a high performance liquid chromatography (HPLC) method for the determination of thirteen selected pharmaceutical compounds (metformin, amoxicillin, chloroquine, theophylline, trimethoprim, caffeine, norfloxacin, ciprofloxacin, acetylsalicylic acid, doxycycline hyclate, metronidazole, albendazole and...
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The recovery of platinum from waste is of high importance since significant concentrations are lost during processing, but the current methods are not economically effective. The removal of Pt4+ from aqueous solutions at different conditions using zeolite functionalised with 3-aminopropyl(diethoxy)methylsilane (APDEMS) was investigated. The adsorbe...
Article
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Pharmaceutical consumption is increasing worldwide as it is essential to treat and prevent health issues but they end up in the environment. However, in many African countries like Ethiopia, the status of these compounds in various environmental samples is not very well known. In this study, a simple method for the extraction and determination of t...
Article
Arsenic and selenium are both carcinogenic and their presence in fresh water has attracted the development of robust and accurate monitoring techniques. A new diffusive gradients in thin-films (DGT) sampler was developed and evaluated for the in situ measurements of arsenic and selenium. The binding layer was made from a mixture of sulphonated and...
Article
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In this article, a comprehensive review of applications of the hollow fibre-liquid phase microextraction (HF-LPME) for the isolation and pre-concentration of pharmaceuticals in water samples is presented. HF-LPME is simple, affordable, selective, and sensitive with high enrichment factors of up to 27,000-fold reported for pharmaceutical analysis. B...
Article
In this work, the concentrations of malathion in fruits were determined using UV-Vis spectrophotometry prior to pre-concentration using QuEChERS. The Z-sep⁺/PSA sorbent combination was used for the d-SPE clean-up and extraction was done using acetonitrile during QuEChERS. The absorbance of malathion was measured using a UV-Vis spectrophotometer at...
Article
In this work, molecularly imprinted polymer (MIP) was synthesized by a bulk polymerization method, characterized and parameters were optimized for adsorption of albendazole, ciprofloxacin, norfloxacin and venlafaxine in aqueous environment. The optimized MIP extraction parameters were adsorbent (MIP) mass 50 mg, sample pH of 9 and adsorption time o...
Article
The occurrence of pharmaceuticals in the environmental waters is a global concern. There is little research conducted on the monitoring of pharmaceuticals in the marine environment. In this article, the occurrence of pharmaceuticals and their metabolites in the coastal waters as well as associated risks related to their uptake by marine organisms a...
Article
In this work, molecularly imprinted polymer (MIP) was synthesized by a bulk polymerization method, characterized and parameters were optimized for adsorption of albendazole, ciprofloxacin, norfloxacin and venlafaxine in aqueous environment. The optimized MIP extraction parameters were adsorbent (MIP) mass 50 mg, sample pH of 9 and adsorption time o...
Article
The presence of trace metals in polluted mine water remains a concern due to its adverse effects on human health. This paper evaluates a PVC-D2EHPA based PIM containing silver nanoparticles as a tool to extract and measure trace metals in polluted water. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), contact angle a...
Chapter
Neutralization that results in the precipitation of high‐density sludge (HDS) remains the preferred method for treating acid mine drainage (AMD). The HDS is usually discharged onto landfills, with little further exploitation and thus poses an environmental challenge. This study proposes aims at using various neutralizing agents (e.g., NaOH, CaCO3,...
Article
Full-text available
Human consumption of non-steroidal anti-inflammatory drugs (NSAIDs) is increasing, which poses a great risk of pollution by these pharmaceuticals on the aquatic environment. Therefore, this study reports the optimization of microwave-assisted extraction using water as a green solvent and hollow fiber liquid-phase microextraction (HF-LPME) methods f...
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Mineral commodities in Earth's crust, such as platinum, palladium, and gold have to be sustained especially since their ore deposits have been dramatically declining, due to intensive mining, motivated by high demand. The mining of these commodities results in large amounts of wastewater containing traces of precious elements. The current study pre...
Article
The shortcomings of conventional sampling methods as grab sampling has led to the development of alternative approaches especially those based on passive samplers. The challenge of passive sampler’s despite being cheap to use and being integrative in nature is that there are limited commercial suppliers especially for those on water related applica...
Chapter
The global deterioration of water quality which is associated with industrialisation, urbanisation, and a growing population is reaching critical levels and thus needs to be addressed urgently. Common pollutants that are discharged from industries and sewage plants include unknown toxic chemicals, heavy-metals and micro-organisms; these are well kn...
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Full-text available
Phytochemicals of Cannabis sativa mainly for the use in the different industries are that of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). Pressurized hot water extraction (PHWE) is seen as an efficient, fast, green extraction technique for the removal of polar and semi-polar compounds from plant materials. The PHWE technique was applie...
Article
Full-text available
Moringa oleifera leaves are widely used in traditional medicine as a food supplement because they are high in essential and nutritious content. Pressurized hot water extraction (PHWE), which is a green approach, was used for the recovery of the macro-nutrient and micro-nutrient elements from dried leaf powder of Moringa oleifera. In this study, res...
Article
Isinuka Springs at Port St Johns in the Eastern Cape Province of South Africa is a traditional spa sacred to the AmaMpondo tribe of the Xhosa speaking people. The bathing pond is considered to have healing powers both spiritually and therapeutically. Hundreds of people flock into the spiritual pond every weekend for both recreational and its spirit...
Article
The scarcity of precious elements such as Pd(II), Ir(III) and Rh(III) has been increasing over the years hence, their recovery from wastewaters using efficient and cheap recovery techniques is becoming more important. In this study, the spent yeast collected after brewing was used to functionalise bentonite clay material to obtain very cheap materi...
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Full-text available
The distribution of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the muscle, liver, spleen and kidney tissue of two fish species was studied using an optimised diatomaceous earth assisted modified QuEChERS extraction method. Five-year-old free-ranging male African sharptooth catfish (Clarias gariepinus) and 5-year...
Article
There is a need for cheap but, efficient methods for the removal of precious metals from wastewaters, which are normally lost during mineral processing. Moreover, the disposal of yeast waste from brewing has been a problem in many parts of the world. In this study, the removal of Pt(IV) from aqueous so- lutions using the readily available bentonite...
Article
Full-text available
The success of any analytical method depends largely on the sample preparation technique which is usually employed for the extraction and pre-concentration of the target analyte from a sample matrix. In this context, solid-phase extraction has been greatly explored by various researchers in many scientific fields including environmental analysis of...
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Full-text available
Increasing applications of rare earth elements (REEs) and improving technologies have led to increased demand. Because of their limited availability and depletion of most resources, the recovery of these elements from waste has become important. The use of cost-effective materials for this purpose and the high value that can potentially be recovere...
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Full-text available
The ever-increasing demand for determining pesticides at low concentration levels in different food matrices requires a preliminary step of pre-concentration which is considered a crucial stage. Recently, the parameter of “greenness” during sample pre-concentration of pesticides in food matrices is as important as selectivity in order to avoid usin...
Article
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Nitrous oxide (N2O) is an important greenhouse gas and is the third-largest contributor to global warming with a global warming potential (GWP) higher than that of carbon dioxide. Ambient N2O is monitored globally and described at nanomole per mole (nmol mol⁻¹) levels. Metrologically traceable and highly accurate N2O gas standards are required to u...
Article
The toxic effects of different atrazine concentrations on tadpoles and adult male African clawed frogs (Xenopus laevis) were assessed in a controlled laboratory environment following 90 days' exposure. The aim was to elucidate the danger of atrazine exposure on the cardiac tissue relative to its critical function of rhythmic contractility, fundamen...
Article
Full-text available
Many rivers in urbanised catchments in South Africa are polluted by raw sewage and effluent to an extent that their ecological function has been severely impaired. The Hennops and Jukskei Rivers lying in the Hartbeespoort Dam catchment are two of the worst impacted rivers in South Africa and are in need of rehabilitation. Passive sampling (Chemcatc...
Article
In recent years, the occurrence of pharmaceuticals including non-steroidal anti-inflammatory drugs in Umgeni River water system in South Africa has been a concern to the scientific community. In this study; naproxen, diclofenac and ibuprofen were isolated from various water samples (river, estuarine and sea water)using the solid-phase extraction te...
Article
Full-text available
An ultrahigh-pressure supercritical fluid extraction method was optimized and applied to extract seed oil lipids from two moringa species, namely Moringa oleifera(MO) andMoringa peregrina(MP). A full-factorial design was used to investigate the direct and interaction influence of pressure and temperature in the range of 40 to 80 MPa and 40 to 70 °C...
Article
Leaching of chromium compounds into the environment from the electroplating process may cause health detrimental effects to humans and ecosystem exposed to these compounds. Ion-imprinted adsorbents possessing high selectivity are required to eradicate trace chromium compounds from complex matrices. A pseudo-surface imprinting technique was applied...
Article
Full-text available
Phytoremediation is a cost-effective, eco-friendly technology for the removal of metals from polluted areas. In this study, six different plant species (Datura stramonium, Phragmites australis, Persicaria lapathifolia, Melilotus alba, Panicum coloratum, and Cyperus eragrostis) growing in a gold mine contaminated wetland were investigated as potenti...
Article
Water pollution due to industrial processes has necessitated and spurred robust research into the development of adsorbent materials for remediation. Polyphenylenediamines (PPD) have attracted significant attention because of their dual cationic and redox properties. They are able to reduce Cr(VI) to Cr(III) in solution. Interrogation of the chemic...
Article
Phosphorus is a micronutrient but when it exists in abundance, it can have detrimental environmental impact. Bentonite (Bent) modified with Fe, Co and Ni salts were synthesized and evaluated for adsorption of phosphate ions from water. Results indicated that metal-modified bentonite have lower crystallinity compared to the native bentonite. Batch a...
Article
Moringa oleifera is an excellent source of bioactive compounds which exhibit nutritional and medicinal properties. Pressurized hot water extraction is known as a green, environmentally, faster and efficient extraction technique. However, it is facing a challenge with the degradation of thermolabile compounds at higher temperature. This research was...
Article
The therapeutic efficacy of antiretroviral drugs as well as challenges and side effects against the human immunodeficiency virus is well documented and reviewed. Evidence is available in literature indication that antiretrovirals are only partially transformed and become completely excreted from the human body in their original form and/or as metab...
Article
A technique that combines membrane assisted solvent extraction and molecularly imprinted polymer into a single step format has been successfully developed and evaluated for the extraction of the 16 US-EPA priority polycyclic aromatic hydrocarbons in wastewater samples followed by determination using gas chromatography coupled with time of flight ma...
Article
Full-text available
A molecularly imprinted polymer (MIP) that is selective to ketoprofen was synthesized and applied in the adsorption of the target compound from water. The MIP was synthesized using a bulk polymerization method at high temperatures (60-80°C), where ketoprofen, 2-vinylpyridine, ethylene glycol dimethacrylate, toluene and 1,1´-azobis(cyclohexanecarbon...
Article
Full-text available
Biosorption has gained much ground as a wastewater treatment technology. In this work, modified algal biosorbents were synthesized by immobilizing Cladophora sp. alga in alginate beads and silica gel. The resultant biosorbents were evaluated for the retrieval of mercury from aqueous solutions using batch scale experiments. Optimal metal removal was...
Article
Sub-chronic toxicity of environmentally relevant atrazine concentrations on exposed tadpoles and adult male African clawed frogs (Xenopus laevis) was evaluated in a quality controlled laboratory for 90 days. The aim of this study was to determine the effects of atrazine on the survival, growth and gonad development of African clawed frogs. After ex...