Search

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 selective and efficient extraction of selected pharmaceuticals belonging to five different classes, namely an antiretroviral (nevirapine), an antidepressant (venlafaxine), a muscle relaxant (methocarbamol), an anticonvulsant (carbamazepine) and a cardiac stimulant (etilefrine) from surface water samples. Cavity tuning experiments using the target pharmaceuticals as a single or multi-template were conducted and the venlafaxine-imprinted polymer was successfully selected for the study based on its high selectivity toward targeted pharmaceuticals. Batch adsorption and kinetic studies showed that adsorption of the selected pharmaceuticals onto the particles of the polymer followed a Freundlich adsorption isotherm as well as a pseudo-second-order adsorption model. This indicated heterogeneity of the binding surface energies on the MIP resulting in multiple interactions through chemisorption. An analytical method for quantification of the compounds using liquid chromatography-mass spectrometry (LC–MS) was successfully developed, with detection limits ranging from 0.03 to 0.31 ng mL−1 and quantification limits in the 0.12–3.81 ng mL−1 range. The imprinted polymer was then evaluated as a selective adsorption sorbent for solid-phase extraction (SPE) of the selected pharmaceuticals in dam water samples followed by LC–MS analysis, giving recoveries ranging from 43 to 69%. [ABSTRACT FROM AUTHOR]

Abstract: Molecularly imprinted polymers (MIPs) targeting quercetin were prepared from 4-vinylpyridine and ethylene dimethacrylate (EDMA) under various solvent systems with the aim to form MIPs with high recognition for the quercetin molecule in aqueous systems at high temperature. A MIP prepared from the three-component solvent mixture of THF/H2O/MeOH showed potential in its application for the determination of quercetin in plants (onion). The polymer particles before and after washing were characterized by infrared spectroscopy and thermogravimetric analysis. Surface morphology was recorded by scanning electron microscopy. The binding capacity of the MIPs was investigated at 25 and 84°C, respectively, in batch mode. Parameters, including the influence of pH, extraction time and binding capacity, were evaluated. The slopes for the effect of extraction time revealed that the mass transfer of the analytes was higher at 84°C than at 25°C. Also, the binding capacity for the most promising MIP and its corresponding NIP was higher at 84°C. The binding capacity for the MIP was ∼30μmolg−1 at 25°C and ∼120μmolg−1 at 84°C, while for the corresponding NIP, it was ∼15 and ∼90μmolg−1, at 25 and 84°C, respectively. A demonstration of MIP selectivity at higher temperature using standard solutions of selected flavonols showed that the MIP still retained its selectivity for quercetin. Similar selectivity was observed when preliminary application studies on aqueous yellow onion extracts were investigated. [Copyright &y& Elsevier]

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. However, the progressive accumulation of Cr(VI) onto the adsorbent surface reduces its adsorption capacity before adsorbent depletion. This factor limits the application of the adsorbent due to high cost and environmental impact related to adsorbent disposal after use. Here, we report the feasibility of different regenerating agents to recover adsorbed Cr(VI) and activate the tunable surface charge of the adsorbent composite to restore its initial adsorption capacity until exhaustion. The recycled PPy-MMT adsorbents were characterized by FTIR, TGA and EDS analysis. At low solution pH, PPy-MMT is protonated resulting in high adsorption capacity for Cr(VI) through electrostatic attraction and ion exchange while simultaneously reducing Cr(VI) to less toxic Cr(III). The spent adsorbents were reversibly subjected to sequential adsorption–desorption cycles between adsorbent neutral state and the oxidized state using different concentrations of regenerating agents including NaOH, NH4OH, HCl, NH4Cl and HNO3, respectively. The results suggested that with 0.01 M NaOH and 0.5 M HCl, PPy-MMT could be used for over five cycles for Cr(VI) removal with more than 80% regeneration efficiency indicating potential applicability as a re-usable adsorbent for Cr(VI) removal. [ABSTRACT FROM AUTHOR]

Pharmaceuticals are organic compounds used in medicines for alleviation of pain. Since 2017, there has been a steady increase on the availability of information on contamination of water resources caused by pharmaceuticals in some African countries. Thus far, most environmental monitoring studies of pharmaceuticals are conducted in South Africa while there is still no available data in majority of the African countries. Therefore, the knowledge on the presence of pharmaceuticals in African water resources is still lacking. In an attempt to provide more information in this aspect, this review article seeks to critically evaluate the progress made thus far by the African scientists in the environmental monitoring and assessment of pharmaceuticals. The most studied groups of pharmaceuticals in Africa are non-steroidal anti-inflammatory drugs, antibiotics, antiretroviral drugs and steroid hormones. Various remediation studies for selected pharmaceuticals in Africa are documented in literature. In the present review, the challenges facing the African researchers or countries on providing more scientific data on the occurrence of pharmaceuticals in water are discussed. Furthermore, the gaps and recommendations for future work are given. • Current status of pharmaceuticals in African water bodies is examined. • NSAIDs, ARVDs, antibiotics and steroid hormones are more prominent in African waters. • Coastal countries are more active in environmental monitoring of pharmaceuticals. • SPE coupled to LC systems is widely used in African countries. • Various adsorbents for removal of pharmaceuticals in contaminated water have been reported. [ABSTRACT FROM AUTHOR]

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, response surface methodology was applied to assess the influence of temperature (50–200 °C) and time (5–60 min) on the extractability pattern of macro-nutrient and micro-nutrient elements from the leaves of Moringa oleifera when processed by PHWE. The quantification of macro-nutrient elements such as Ca, K and Mg and micro-nutrient elements like Al, Co, Cr, Cu, Fe, Ni and Zn from the leaves was determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). Obtained results revealed that the extraction of macro-nutrient elements from the Moringa oleifera leaves was enhanced by increasing the extraction time more than the extraction temperature. On the contrary, the amounts of extractable micro-nutrient elements were increased by increasing the extraction temperature. Hence, the recovery for macro-nutrient elements ranged from 88 to 98% while for micro-nutrients it ranged from 21 to 46%. This implies that macro-nutrient elements are extracted with relatively high selectivity in relation to micro-nutrient elements in Moringa dried leaf powder using the PHWE technique. [ABSTRACT FROM AUTHOR]

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 mass spectrometry. The technique involves placing the polymer particles into a hydrophobic polypropylene membrane bag which is in contact with an aqueous donor phase. The technique was optimized for various parameters that include presence of an organic modifier in the donor phase, stirring rate and extraction time. The optimum conditions were 25% of dimethyl sulfoxide as an organic modifier and stirring at 1000 rpm for 120 min. The limits of detection using the technique were in the 0.01–0.45 ng mL −1 range. Linearity values determined in the 10–1 000 ng mL −1 calibration range were all above 0.9972. Extraction efficiencies of the sixt analytes calculated as averages for three spiking concentrations ranged from 62.8 to 96.8% (RSD = 3.1–12.3%). The optimized method was tested for the extraction of polycyclic aromatic hydrocarbons in wastewater samples in the presence of surrogate standards. The developed method showed great reproducibility with inter day repeatability values ranging from 0.6 to 24.9%. The analytes were quantified in the nanogram level showing that the developed technique is a viable alternative in the analysis of trace organic compounds in complex aqueous samples. [ABSTRACT FROM AUTHOR]

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(cyclohexanecarbonitrile) were used as template, functional monomer, cross-linker, porogen and initiator, respectively. Non-imprinted polymer (NIP) was synthesized similarly to the MIP but in the absence of ketoprofen. From molecular dynamics simulation, the nature of interactions that occurred between the template and the functional monomer were found to be based on hydrogen bonding. This was confirmed experimentally, where a high extraction efficiency of = 90% was obtained at acidic conditions (pH 5) due to the protonation of ketoprofen. A contact time of 45 min was sufficient for the maximum adsorption of ketoprofen from 10 mL spiked water using 8 mg of the adsorbent. MIP showed greater selectivity than NIP by achieving a relative selectivity coefficient of 7.7 towards ketoprofen in the presence of structurally related pharmaceuticals. Furthermore, the order of sorption onto the MIPs from water was ketoprofen > fenoprofen > gemfibrozil. From a modelling perspective, the Langmuir adsorption isotherm and pseudo-second-order kinetic model gave the best fit, with maximum adsorption capacity of 8.24 mg·g-1 and sorption rate constant of 0.25 mg·g-1·min-1 for MIP. This was translated to chemisorption of ketoprofen onto the homogeneous MIP binding sites. This work demonstrated the great potential of MIP in selective recognition of ketoprofen from wastewater relative to closely related compounds. [ABSTRACT FROM AUTHOR]

A smart sorbent consisting of benzo[k]fluoranthene-imprinted and indeno[1 2 3-cd]pyrene-imprinted polymers mixed at 1:1 (w/w) was successfully screened from several cavity-tuning experiments and used in the isolation of polycyclic aromatic hydrocarbons from spiked solution. The polymer mixture showed high cross selectivity and affinity towards all the 16 US-EPA priority polycyclic aromatic hydrocarbons. The average extraction efficiency from a cyclohexane solution was 65 ± 13.3% (n = 16, SD). Batch adsorption and kinetic studies confirmed that the binding of polycyclic aromatic hydrocarbons onto the polymer particles resulted in formation of a monolayer and that the binding process was the rate limiting step. The imprinted polymer performance studies confirmed that the synthesized polymer had an imprinting efficiency of 103.9 ± 3.91% (n = 3, SD). A comparison of the theoretical number of cavities and the experimental binding capacity showed that the overall extent of occupation of the imprinted cavities in the presence of excess polycyclic aromatic hydrocarbons was 128 ± 6.45% (n = 3, SD). The loss of selectivity was estimated at 2.9% with every elution cycle indicating that the polymer can be re-used several times with limited loss of selectivity and sensitivity. The polymer combination has shown to be an effective adsorbent that can be used to isolate all the 16 US-EPA priority polycyclic aromatic hydrocarbons in solution. [ABSTRACT FROM AUTHOR]

A liquid phase microextraction based on hollow fibre followed by liquid chromatographic determination was developed for the extraction and quantitation of the hallucinogenic muscimol from urine samples. Method applicability on polar hallucinogens was also tested on two alkaloids, a psychedelic hallucinogen, tryptamine and a polar amino acid, tryptophan which exists in its charged state in the entire pH range. A multivariate design of experiments was used in which a half fractional factorial approach was applied to screen six factors (donor phase pH, acceptor phase HCl concentration, carrier composition, stirring rate, extraction time and salt content) for their extent of vitality in carrier mediated liquid microextractions. Four factors were deemed essential for the effective extraction of each analyte. The vital factors were further optimized for the extraction of single-spiked analyte solutions using a central composite design. When the simultaneous extraction of analytes was performed under universal factor conditions biased towards maximizing the enrichment of muscimol, a good composite desirability value of 0.687 was obtained. The method was finally applied on spiked urine samples with acceptable enrichments of 4.1, 19.7 and 24.1 obtained for muscimol, tryptophan and tryptamine respectively. Matrix-based calibration curves were used to address matrix effects. The r 2 values of the matrix-based linear regression prediction models ranged from 0.9933 to 0.9986. The linearity of the regression line of the matrix-based calibration curves for each analyte was directly linked to the analyte enrichment repeatability which ranged from an RSD value of 8.3–13.1%. Limits of detection for the developed method were 5.12, 3.10 and 0.21 ng mL −1 for muscimol, tryptophan and tryptamine respectively. The developed method has proven to offer a viable alternative for the quantitation of muscimol in human urine samples. [ABSTRACT FROM AUTHOR]

• A novel MASE-MIP based passive sampler was developed for five pharmaceuticals • An ionic liquid was utilized as a green receiver solution for the passive sampler • Matrix-matched sampling rates achieved ranged from 0.0007 - 0.0018 L d−1 • Only etilefrine (12.88 ng L−1) and methocarbamol (72.29 ng L−1) were quantified • Other drugs were not detected with detection limits from 2.45 - 3.26 ng L−1 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. Passive sampling was based on the diffusion of the target pharmaceuticals from surface water through a membrane bag which housed an ionic liquid as a green receiving solvent and a molecularly imprinted polymer. Effects of biofouling, deployment time and solvent type for the receiver phase were optimized for selective uptake of analytes in surface water. Notably, there was a decrease in the uptake of selected pharmaceuticals and consequently a decrease in their sampling rates in the presence of biofouling. The optimum matrix-matched sampling rates ranged from 0.0007 - 0.0018 L d−1 whilst the method detection and quantification limits ranged from 2.45 - 3.26 ng L−1 and 8.06 - 10.81 ng L−1, respectively. The optimized passive sampler was deployed in a dam situated in the heart of a typical highly populated township in the Gauteng Province of South Africa. Only etilefrine and methocarbamol were detected and quantified at maximum time weighted average concentrations of 12.88 and 72.29 ng L−1, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

In Africa, ochre is ubiquitous in archaeological sites after 100 ka and likely served a symbolic role in the lives of prehistoric people. Archaeological excavation of the c. 100–72 ka Middle Stone Age (MSA) levels at Blombos Cave (BBC) located in the southern Cape, South Africa, have yielded significant amounts of ochre as artefacts or residues. Although recent archaeological evidence from BBC and elsewhere has provided remarkable insights into the ways that ochre was used, for example its use as a pigmented ‘paint’, the significance of ochre can be further understood by studying its procurement pattern. To this end, the geochemical characterisation of recovered ochre can tell us about the temporal and spatial variation present at a site. The analysis of BBC ochre was accomplished using FTIR, ED XRF, ICP OES and XRD with the aim of determining the mineral and elemental composition variability of ochre across layers and thereby gauging whether there were preferred or different ochre procurement patterns or sources over time. For example, it was found that ochre residues from the c. 100 ka CP layer had kaolinite and quartz as the principal minerals, while ochre residues from the c. 97 ka CJ layer consisted mainly of calcite and quartz. Thus, mineral composition can indicate procurement of different sources of ochre during the various stages of the cave occupation. Elemental analysis of ochre residues from the c. 77–72 ka Still Bay, CJ and CP layers also revealed differences in minor and trace elements. These findings seem to indicate some differences in the ochre from these levels and can also be taken as an indication of different ochre sourcing. [ABSTRACT FROM AUTHOR]

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 surface water samples followed by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-qTOF/MS) determination. A central composite design was applied to optimize the influence of the sample salt content, the stirring rate, the stirring time and the amount of MIP on the extraction of an anticonvulsant (carbamazepine), a cardiac stimulant (etilefrine), a muscle relaxant (methocarbamol), an antiretroviral (nevirapine) and an antidepressant (venlafaxine) from surface water. Optimization of the analytical method was performed by spiking water with a mixture of all five pharmaceuticals at 500 ng mL−1. Optimum extraction conditions for a sample volume of 18 mL were found to be 5 g of salt content, a stirring rate of 400 rpm, an extraction time of 60 min and 50 mg of MIP. The MASE-MIP-LC-qTOF/MS method gave detection and quantification limits ranging from 0.09 to 0.20 ng mL−1 and 0.31–0.69 ng mL−1, respectively. The spiked river water samples yielded recoveries ranging from 38 to 91% for the selected model compounds belonging to the five classes of pharmaceuticals. Upon the application of the developed analytical method in water analysis, all selected pharmaceuticals were detected in South African river water with nevirapine and venlafaxine being more prominent attaining the maximum concentrations of 1.64 and 2.48 ng mL−1, respectively. [Display omitted] • A MASE-MIP technique was developed for monitoring pharmaceuticals in water samples. • Optimization of the analytical method was done using a central composite design. • Good experimental and statistical method performances were observed. • Method was applied in extraction of 5 pharmaceutical classes in river water. • Nevirapine (1.64 ng mL−1) and venlafaxine (2.48 ng mL−1) were more prominent. [ABSTRACT FROM AUTHOR]

Abstract: A selective extraction technique based on the combination of liquid membrane (microporous membrane liquid–liquid extraction) and molecularly imprinted polymers (MIP) was applied to triazines herbicides in food samples. Simazine, atrazine and propazine were extracted from aqueous food samples through the hydrophobic porous membrane that was impregnated with toluene, which also formed part of the acceptor phase. In the acceptor phase, the compounds were re-extracted onto MIP particles. The extraction technique was optimised for the amount of molecularly imprinted polymers particles in the organic acceptor phase, extraction time, and type of organic acceptor solvent and desorption solvent. An extraction time of 90min and 50mg of MIP were found to be optimum parameters. Toluene as the acceptor phase was found to give higher triazines binding onto MIP particles compared to hexane and combinations of diethyl ether and hexane. 90% methanol in water was found to be the best desorption solvent compared to acetonitrile, methanol and water. The selectivity of the technique was demonstrated by extracting spiked lettuce and apple extracts where clean chromatograms were obtained compared to liquid membrane extraction alone or to the microporous membrane liquid–liquid extraction – non-imprinted polymer combination. The MIP showed a certain degree of group specificity and the extraction efficiency in lettuce extract was 79% (0.72) for simazine, 98% (1.55) for atrazine and 86% (3.08) for propazine. [Copyright &y& Elsevier]

• HF-LPME was developed for pre-concentration of antiretroviral drugs. • Antiretroviral drugs were detected in water and aquatic plants. • Efavirenz had the highest concentration of 37.6 μg L−1 in wastewater effluent. • Translocation occurred from roots of water hyacinth plant to aerial tissues. This work describes a simple and sensitive method for the simultaneous isolation, enrichment, identification and quantitation of selected antiretroviral drugs; emtricitabine, tenofovir disoproxil and efavirenz in aqueous samples and plants. The analytical method was based on microwave extraction and hollow fibre liquid phase microextraction technique coupled with ultra-high pressure liquid chromatography-high resolution mass spectrometry. A multivariate approach via a half-fractional factorial design was used focusing on six factors; donor phase pH, acceptor phase HCl concentration, extraction time, stirring rate, supported liquid membrane carrier composition and salt content. The optimal enrichment factors for emtricitabine, tenofovir disoproxil and efavirenz from aqueous phase were 78, 111 and 24, respectively. The analytical method yielded recoveries in the range of 86 to 111%, and quantitation limits for emtricitabine, tenofovir disoproxil and efavirenz in wastewater were 0.033, 0.10 and 0.53 μg L−1, respectively. The drugs were detected in most samples with concentrations up to 37.6 μg L−1 recorded for efavirenz in wastewater effluent. Roots of the water hyacinth plant had higher concentrations of the investigated drugs ranging from 7.4 to 29.6 μg kg−1. Overall, hollow fibre liquid phase microextraction proved to be an ideal tool for isolating and pre-concentrating the selected antiretroviral drugs from environmental samples. [ABSTRACT FROM AUTHOR]

Diospyros batokana (Ebenaceae) is a valuable medicinal plant that grows in the wild in Zambia. The aqua crude plant extract is valuable in treating oxidative stress and microbes-related diseases. In this study, bioactive metabolites from the leaf of the plant were tentatively identified using ultra-high-pressure liquid chromatography tandem high-resolution mass spectrometry (UHPLC-HRMS). Raw LCMS data were processed using MZmine3.6. Pyrenophorol, N-[1-(diethylamino)-3-morpholin-4-ylpropan-2-yl]-2,2-diphenylacetamide, losartan, and isoarthonin, (2E,4E)-N-[2-(4-hydroxyphenyl)ethyl]dodeca-2,4-dienamide were among the many metabolites identified from the plant studied using LCMS-MZmine 3.6. Furthermore, in silico anti-inflammatory molecular docking was applied to the five (5) metabolites with the aim of predicting the ability of the metabolites to inhibit the COX-2 enzyme. The docking simulation for the five metabolites was executed using the Auto-dock tools. The lowest binding energy of the complexes was visualized using Discovery Studio, 2021 Client l molecular viewer. Pyrenophorol, (N-[1-(diethylamino)-3-morpholin-4-ylpropan-2-yl] -2,2-diphenylacetamide) and losartan were found to provide the lowest binding energy to COX-2 compared to the standard anti-inflammatory drug, diclofenac. Furthermore, binding affinities, inhibition constants, and ligand efficiencies demonstrated that pyrenophorol, N-[1-(diethylamino)-3-morpholin-4-ylpropan-2-yl]-2,2-diphenylacetamide, losartan, isoarthonin and (2E,4E)-N-[2-(4-hydroxyphenyl)ethyl]dodeca-2,4-dienamide could be useful as anti-inflammatory drug candidates supporting the traditional uses of D. batokana . However, the bioavailability radar and physicochemical properties only predict losartan, pyrenophorol, and (2E,4E)-N-[2-(4-hydroxyphenyl)ethyl]dodeca-2,4-dienamide to be bioavailable and suitable drug candidates. In silico and ADMET analysis, shows that the five metabolites could be used as anti-inflammatory drugs comparable to the standard drugs, diclofenac and ibuprofen. However, in vitro and in vivo studies are needed to further support our findings., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Author(s).)

Globally, per- and polyfluoroalkyl substances (PFAS)-related research on paper products has focused on food packaging with less consideration on the presence of PFAS at different stages of the paper recycling chain. This study analysed the prevalence of PFAS in paper grades used for the manufacture of recycled paperboard. The presence of PFAS was attributed to the use of PFAS-containing additives, consumer usage, exposure to packed goods as well as contamination during mingling, sorting, collection, and recovery of paper recycling material. Q Orbitrap mass spectrometry was used to analyse the paper samples after accelerated solvent extraction and solid phase extraction. The distribution and possible propagation of 22 PFAS were determined in pre-consumer, retail and post-consumer paper products. Post-consumer samples had the highest combined average concentration (ΣPFAS) at 213 ng/g, while the ΣPFAS in retail (159 ng/g) and pre-consumer samples (121 ng/g) was detected at lower concentrations. This study showed that waste collection and recycling protocols may influence PFAS propagation and that measures must be developed to minimise and possibly eliminate exposure opportunities., (© 2024. The Author(s).)

This study responds to stringent environmental regulations and increasing focus on resource conservation by exploring economically viable refining technologies through recycling. With the rising costs of filtrate disposal, there is a significant emphasis on removing and recycling valuable constituents, particularly nickel and copper (Ni and Cu). Herein, we employ analytical techniques with the aim of investigating an alternative method for recovering Ni and other valuable metals from a nickel sulfide-fire assay filtrate using S -curve precipitation under optimal conditions. The waste from the fire assay procedure contains substantial amounts of Ni and other critical metals, with concentrations of 62.7 g/L of Ni and 3.87 g/L of Cu. Prior to precipitation, traditional solvent extraction was used for Cu extraction, selectively removed before separating primary impurities such as iron (Fe). A pivotal aspect of this research involves applying S -curve precipitation with precise parameters at different pH levels. Analytical techniques reveal a minor depletion occurs as Ni is separated from Fe at a pH of 2.5, resulting in the formation of a refined Ni stream that is then refined into a mixed hydroxide Ni(OH) 2 product. The efficiency of 5,8-diethyl-7-hydroxydodecan-6-oxime (LIX 63-70) in extracting value-added metals from fire assay waste is exceptionally high, integrating recycling and repurposing of value-added base metals to promote a circular economy., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Microplastics (MPs) have emerged as a global environmental concern due to their persistent nature. In South Africa, microplastic research has primarily focused on marine systems. However, recent years have seen a shift in focus to studying MPs in South African freshwaters. In this study, MPs with a minimum size of 0.055 mm in surface water of the Vaal River, South Africa, were reported. MPs were 100% prevalent, with a mean numerical abundance of 0.68 ± 0.64 particles/m 3 . Small-sized MPs of < 1 mm accounted for the largest proportion. MPs were chemically identified as high-density polyethylene, low-density polyethylene, and polypropylene according to their Raman spectra. The prevalence of fragments (41.6%) and fibers (38.5%) over pellets (8.1%) indicates that microplastics are from secondary sources. The prevalence of polyethylene and polypropylene is consistent with microplastics being from secondary sources. These polymers are commonly used in single-use plastics, packing bags, textiles, and containers. These characteristics are of great concern due to their implications on the bioavailability and toxicological impacts of MPs. Consequently, these properties may pose more hazards to aquatic biota inhabiting the Vaal River., (© 2024. The Author(s).)

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 pollutants (POPs) is scanty. The sampling was designed to simulate POP bioaccumulation in benthic and aquatic dwelling organisms as well as ambient air for estimation of ecological risk. The objective was to survey the spatiotemporal distribution and fate of bioavailable priority persistent organic compounds in the Hartbeespoort Dam in summer, autumn and winter seasons and to validate the utility of a comprehensive two-dimensional gas chromatography-time of flight mass spectrometry (GCxGC-TOF) method for PCDD/F, PCB, and PBB analysis. The highest detection rates for bioavailable priority POPs were for PCB 77 and PCB 126 which were detected in 15 and 16 of the 22 samples, though the majority of the detections were < LOQ for PCB 77. Overall, PCB 126, PBB 10 and PBB 49 recorded the highest quantified bioavailable concentrations per site in SPMDs deployed in the Hartbeespoort Dam. The SPMDs deployed in air at the Magalies River site in winter recorded the highest toxic equivalency quotient (TEQ) of 29.77 pg TEQ SPMD -1 . The highest TEQs recorded for SPMDs deployed in the sediment phase were 10.2, 3.3, and 3.2 pg TEQ SPMD -1 , recorded at the Harbour site in summer, Dam wall in summer and Harbour in winter respectively. In water, SPMDs deployed at the Crocodile River site recorded the highest TEQ of 0.81 pg TEQ SPMD -1 in summer. TEQ data shows that air carries significant bioavailable dl-toxicity compared to the water phase, and sediment generally carries the highest dl-toxicity. Detection rates for bioavailable PBBs were generally very low, with < 3 detections being quantified above the LOQ for the majority of the sites. Statistical analysis of TEQs computed at all sites, using AVOVA shows that the dispersion of TEQs in the Hartbeespoort Dam is largely homogenous as the differences between the TEQs were insignificant (p > 0.05)., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

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 thirteen pharmaceutical compounds of different therapeutic classes in water samples using solid-phase extraction and HPLC-DAD was developed. Different parameters affecting extraction were optimised and obtained as hydrophilic-lipophilic balance (HLB) extraction cartridge, water sample pH of 5, elution solvent of 2% formic acid in water with methanol (20:80%, v/v), a sample volume of 150 mL and addition of 0.5% w/v EDTA in the sample. The limits of detection and quantification of the optimised method were in the range of 0.1-0.8 µg/L and 0.2-2.6 µg/L, respectively. The relative recovery in the spiked environmental water sample was in the range of 70-117% except for amoxicillin and acetylsalicylic acid in influent wastewater. The precision for all ranged from 0.3 to 11%. The proposed method was successfully tested for the detection and quantification of different environmental water samples collected from Addis Ababa, Ethiopia. Trimethoprim, caffeine and albendazole concentrations of 7.8 (1.1), 3.2 (0.4) and 2.1 (0.1) µg/L were quantified in hospital wastewater, respectively. The concentration of norfloxacin was found to be below the limit of quantification in the same water. Trimethoprim and ciprofloxacin were also found in the sewage treatment plant influent sample at a concentration of 0.5 (0.02) and 0.3 (0.01) µg/L, respectively.

A study of the distribution of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) utilising 16 priority PAHs, benzo(e)pyrene, perylene, 19 alkylated PAHs and 31 ortho substituted PCBs in South Africa is presented. It was aimed to (a) deduce characteristic contamination patterns for both PCBs and PAHs and (b) provide the first comprehensive dataset for establishment of source characterisation of PCBs and PAHs. This is in line with new South African legislation on mandatory monitoring of PCB and PAH emissions. Bar charts, principal component analysis (PCA) and biplots were utilised to identify signature contamination patterns and distribution of PCBs and PAHs within the Jukskei and Klip Rivers. Sediments from the Jukskei and Klip River catchments both showed distinct contamination signatures for hexa to nonachlorinated PCBs, characteristic of contamination by Aroclor 1254 and 1260 technical mixtures. PCB signature patterns in order of abundance were 138 > 180 > 206 > 153 > 187 > 149 and 138 > 153 > 180 > 149 > 187 > 110 > 170 for the Jukskei and Klip River sediments, respectively. The upstream Alberton point had the highest Σ31 PCB and Σ (parent+alkyl) PAH concentrations in the Klip River of 61 and 6000 μg kg -1 dry weight (dw), respectively. In the Jukskei River, the upstream Marlboro point had the highest Σ31 PCB concentration of 19 μg kg -1 dw and the N14 site recorded the highest Σ (parent+alkyl) PAH concentration of 2750 μg kg -1 dw. PAH concentrations in both the Jukskei and Klip Rivers were significantly higher than the PCB concentrations. Fluoranthene, phenanthrene and pyrene were found in the highest concentrations in both the Jukskei and Klip River sediments. Both the Jukskei and Klip River sediments showed trends of a mixed pyrogenic-petrogenic PAH source contamination.

The present paper reports a detailed study that is based on the monitoring of naproxen, ibuprofen, and diclofenac in Mbokodweni River and wastewater treatment plants (WWTPs) located around the city of Durban in KwaZulu-Natal Province of South Africa. Target compounds were extracted from water samples using a multi-template molecularly imprinted solid-phase extraction prior to separation and quantification on a high-performance liquid chromatography equipped with photo diode array detector. The analytical method yielded the detection limits of 0.15, 1.00, and 0.63 μg/L for naproxen, ibuprofen, and diclofenac, respectively. Solid-phase extraction method was evaluated for its performance using deionized water samples that were spiked with 5 and 50 μg/L of target compounds. Recoveries were greater than 80% for all target compounds with RSD values in the range of 4.1 to 10%. Target compounds were detected in most wastewater and river water samples with ibuprofen being the most frequently detected pharmaceutical. Maximum concentrations detected in river water for naproxen, ibuprofen, and diclofenac were 6.84, 19.2, and 9.69 μg/L, respectively. The concentrations of target compounds found in effluent and river water samples compared well with some studies. The analytical method employed in this work is fast, selective, sensitive, and affordable; therefore, it can be used routinely to evaluate the occurrence of acidic pharmaceuticals in South African water resources.

This study describes the application of multi-template molecularly imprinted polymer (MIP) as selective sorbent in the solid-phase extraction (SPE) of naproxen, ibuprofen and diclofenac from wastewater and river water. MIP was synthesized at 70°C by employing naproxen, ibuprofen and diclofenac as multi-templates, ethylene glycol dimethacrylate, 2-vinyl pyridine and toluene as cross-linker, functional monomer and porogen, respectively. Wastewater and river water samples (pH 2.5) were percolated through SPE cartridge packed with 50mg of the MIP. The cartridge was washed with 2mL of methanol-water 10:90% (v:v) prior to elution with 2mL of acetic acid-acetonitrile 20:80% (v:v). Quantification of eluted compounds was performed with high performance liquid chromatography equipped with photo diode array detection. The detection limits were 0.15, 1.00 and 0.63μgL(-1) for naproxen, ibuprofen and diclofenac, respectively. Recoveries for naproxen, ibuprofen and diclofenac in deionized water spiked at 5 and 50μgL(-1) were greater than 80%. Ibuprofen was the most frequently detected compound with maximum concentrations of 221, 67.9 and 11.4μgL(-1) in wastewater influent, effluent and river water, respectively., (Copyright © 2016 Elsevier B.V. All rights reserved.)

In this study, the semipermeable membrane device (SPMD) passive samplers were used to determine freely dissolved concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in selected water bodies situated in and around Johannesburg City, South Africa. The devices were deployed for 14 days at each sampling site in spring and summer of 2011. Time weighted average (TWA) concentrations of the water-borne contaminants were calculated from the amounts of analytes accumulated in the passive samplers. In the area of interest, concentrations of analytes in water ranged from 33.5 to 126.8 ng l(-1) for PAHs, from 20.9 to 120.9 pg l(-1) for PCBs and from 0.2 to 36.9 ng l(-1) for OCPs. Chlorinated pesticides were mainly composed of hexachlorocyclohexanes (HCHs) (0.15-36.9 ng l(-1)) and dichlorodiphenyltrichloromethane (DDT) with its metabolites (0.03-0.55 ng l(-1)). By applying diagnostic ratios of certain PAHs, identification of possible sources of the contaminants in the various sampling sites was performed. These ratios were generally inclined towards pyrogenic sources of pollution by PAHs in all study sites except in the Centurion River (CR), Centurion Lake (CL) and Airport River (AUP) that indicated petrogenic origins. This study highlights further need to map up the temporal and spatial variations of these POPs using passive samplers.

A new type of ion imprinted polymer (IIP) embedded with γ-methacryloxypropyltrimethoxysilane (γ-MPS) coated magnetic particles for selective extraction of uranyl ions was synthesized by bulk polymerization. The performance of the magnetic sorbent on the extraction of U(VI) was evaluated by various parameters which included the influence of pH, amount of the magnetic polymers, contact time and initial U(VI) concentration. The adsorption capacity of the magnetic polymers was found to be 1.1 and 0.95mgg(-1) for the IIP and its control ion non-imprinted polymer (NIP), respectively. The optimum amount of the sorbent was 50mg for an initial concentration of 2.5mgL(-1). The prepared magnetic imprinted sorbent displayed an uptake with a time of 45min considered optimum. The magnetic polymer displayed good selectivity and exhibited good reusability. Studies from binary mixtures of metal ions in aqueous solutions showed that the magnetic adsorbent selectivity following the order: U(VI)>Ni(II)>Pb(II). Experimental results illustrated the potential application of magnetic ion imprinted polymer sorbents for selective removal of U(VI) from contaminated water., (Copyright © 2013 Elsevier B.V. All rights reserved.)