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Abayneh A. Ambushe
Research Centre for Synthesis and Catalysis, Department of Chemical Sciences, University of Johannesburg, Auckland Park, Johannesburg 2006, South Africa

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Journal article
Published: 19 August 2021 in Minerals
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The use of living plants to recover precious metals with potential catalytic activity is still at the infant stage. In this study, selective hydrogenation of furfural to furfuryl alcohol using novel bio-ore catalysts recovered from the end stage of phytomining process is demonstrated. The phytomining process was carried out in the green house by artificially contaminating cassava (Manihot esculenta) plant with 500 mg/L palladium (Pd) and platinum (Pt) solutions for a period of eight weeks. After harvesting, concentrations of metals as high as 78 ± 0.047 and 1276 ± 0.036 µg/g of Pd and Pt, respectively, were detected in the calcinated root of cassava. The produced bio-ore catalysts; @PdCassCat and @PtCassCat were fully characterized with the following techniques: transmission electron microscopy (TEM), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), powder X-ray diffraction (pXRD), N2-sorption, and UV-visible spectroscopy techniques and directly applied as catalysts for hydrogenation of furfural to furfuryl alcohol. The reaction was conducted under an optimized condition (furfural (10 mmol), triethylamine (Et3N) (10 mmol), formic acid (20 mmol), temperature (160 °C), catalyst amount (40 mg)) realizing a yield of 76.5% and 100% furfuryl alcohol using @PdCassCat and @PtCassCat, respectively. The catalytic activities of the @PdCassCat and @PtCassCat were excellent as well as recyclable up to four and five times, respectively.

ACS Style

Babatunde J. Akinbile; Leah C. Matsinha; Banothile C. E. Makhubela; Abayneh A. Ambushe. Towards Sustainability Pathway with Bio-Derived Platinum and Palladium Catalyst for Furfural Hydrogenation—A Novel Greener Approach in Catalysis. Minerals 2021, 11, 895 .

AMA Style

Babatunde J. Akinbile, Leah C. Matsinha, Banothile C. E. Makhubela, Abayneh A. Ambushe. Towards Sustainability Pathway with Bio-Derived Platinum and Palladium Catalyst for Furfural Hydrogenation—A Novel Greener Approach in Catalysis. Minerals. 2021; 11 (8):895.

Chicago/Turabian Style

Babatunde J. Akinbile; Leah C. Matsinha; Banothile C. E. Makhubela; Abayneh A. Ambushe. 2021. "Towards Sustainability Pathway with Bio-Derived Platinum and Palladium Catalyst for Furfural Hydrogenation—A Novel Greener Approach in Catalysis." Minerals 11, no. 8: 895.

Journal article
Published: 16 August 2021 in Minerals
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Adsorption has become an attractive method for the extraction and recovery of metals from wastewater effluents. This study involved the fabrication of mesoporous neat polyacrylonitrile (PAN) monoliths and composite polymer monoliths of PAN and poly-4-vinylpyridine (P4VP) as adsorbents for toxic elements (As(V), Cr(VI)) and the recovery of PGMs(Ru(III), Rh(III), Pd(II)) from simulated wastewater solutions. Fabrication of the mesoporous polymer monoliths was conducted using the non-solvent induced phase separation method (NIPS). The monoliths were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Brunauer–Emmett–Teller (BET). Adsorption studies were conducted using crushed monoliths saturated in 1 mg·L−1 simulated wastewater solutions. Spectroscopic analyses of the resulting filtrates were conducted using inductively coupled plasma-optical emission spectrometry (ICP-OES). In this study, the NIPS method was successfully optimized and mesoporous PAN, as well as composite polymer monoliths, were successfully fabricated. A concentration of 1 mg·L−1 of Ru(III) and Pd(II) was completely adsorbed by both monoliths. The mesoporous composite polymer monoliths exhibited the highest adsorption capacity for Rh(III), As(V), and Cr(VI). The mesoporous polymer monoliths showed great potential for use as wastewater cleaning aids as well as remediators of precious metals.

ACS Style

Keziah E. Liebenberg; Abayneh A. Ambushe; Orpah Zinyemba. Adsorption of Selected Heavy and Precious Metals from Simulated Wastewater Using Fabricated Polyacrylonitrile (PAN) and Poly(4-Vinylpyridine) (P4VP) Monoliths. Minerals 2021, 11, 884 .

AMA Style

Keziah E. Liebenberg, Abayneh A. Ambushe, Orpah Zinyemba. Adsorption of Selected Heavy and Precious Metals from Simulated Wastewater Using Fabricated Polyacrylonitrile (PAN) and Poly(4-Vinylpyridine) (P4VP) Monoliths. Minerals. 2021; 11 (8):884.

Chicago/Turabian Style

Keziah E. Liebenberg; Abayneh A. Ambushe; Orpah Zinyemba. 2021. "Adsorption of Selected Heavy and Precious Metals from Simulated Wastewater Using Fabricated Polyacrylonitrile (PAN) and Poly(4-Vinylpyridine) (P4VP) Monoliths." Minerals 11, no. 8: 884.

Journal article
Published: 12 August 2021 in Minerals
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In this study, the sequential extraction method was applied to extract selected potentially toxic elements (PTEs) (Cd, Cr, Cu, Fe, Ni, Pb and Zn) in river sediments collected from the Blood River situated in Seshego area, Limpopo Province, South Africa. The study aimed to assess a possible trend of mobilisation of these elements from sediment to water. The accuracy of the sequential extraction method was confirmed by analysing sediment-certified reference material, and quantitative percentage recoveries ranging from 86 to 119%, 81 to 111% and 77 to 119% were achieved for exchangeable, reducible and oxidisable fractions, respectively. The potential risk of the PTEs in sediments was evaluated. The calculated values of contamination factor (CF) as well as risk assessment code (RAC) for Cd, Cu, Ni and Pb revealed the mobility of these elements. The PTEs in river sediments are at a high toxicity-risk level and could therefore cause a threat to organisms dwelling in sediments and humans via consumption of crops irrigated with the polluted river water.

ACS Style

Dithobolong L. Matabane; Taddese W. Godeto; Richard M. Mampa; Abayneh A. Ambushe. Sequential Extraction and Risk Assessment of Potentially Toxic Elements in River Sediments. Minerals 2021, 11, 874 .

AMA Style

Dithobolong L. Matabane, Taddese W. Godeto, Richard M. Mampa, Abayneh A. Ambushe. Sequential Extraction and Risk Assessment of Potentially Toxic Elements in River Sediments. Minerals. 2021; 11 (8):874.

Chicago/Turabian Style

Dithobolong L. Matabane; Taddese W. Godeto; Richard M. Mampa; Abayneh A. Ambushe. 2021. "Sequential Extraction and Risk Assessment of Potentially Toxic Elements in River Sediments." Minerals 11, no. 8: 874.

Journal article
Published: 19 July 2021 in Journal of Environmental Science and Health, Part A
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The presence of coal-based power plants and coal mine in the Waterberg area subjects the Mokolo River to potentially toxic elements (PTEs) such as mercury (Hg). Mercury is an extremely toxic element. Thus, monitoring and chemical speciation of Hg in water bodies; particularly in sediments is a vital tool for assessing water quality. The objective of this study was to investigate the levels of Hg(II) and methyl Hg (MeHg(I)) in sediment samples collected from Mokolo River in different seasons, as well as examining factors such as pH, temperature and organic matter content, which could affect Hg methylation rates. An ultrasonic based method was used for the extraction of Hg species in sediments. This was followed by the chromatographic separation and detection of Hg(II) and MeHg(I) by the on-line coupling of high-performance liquid chromatography (HPLC) to inductively coupled plasma-mass spectrometry (ICP-MS). A solution containing HCl and 2-mercaptoethanol was employed for the extraction of Hg species in sediments. Separation of the two species of Hg was achieved using isocratic elution mode with a mobile phase containing L-cysteine, 2-mercaptoethanol, ammonium acetate and methanol. The accuracy of the method was checked and yielded a percentage recovery of 86%. The Hg(II) concentrations ranged from 38.4 to 89.05 ng g−1 and 34.8 to 57.3 ng g−1 in low and high flow seasons, respectively. The concentrations of MeHg(I) ranged from 0.702 to 4.5 ng g−1 and 0.5 to 2.5 ng g−1 in the low and high flow seasons, respectively. Factors such as pH and temperature were found to influence the methylation rates, however correlation couldn’t be established to organic matter content due to similar amount of organic matter in all the samples.

ACS Style

Dipuo P. Kgabi; Abayneh A. Ambushe. Speciation and bioavailability of mercury in sediments from Mokolo River, Limpopo Province, South Africa. Journal of Environmental Science and Health, Part A 2021, 1 -11.

AMA Style

Dipuo P. Kgabi, Abayneh A. Ambushe. Speciation and bioavailability of mercury in sediments from Mokolo River, Limpopo Province, South Africa. Journal of Environmental Science and Health, Part A. 2021; ():1-11.

Chicago/Turabian Style

Dipuo P. Kgabi; Abayneh A. Ambushe. 2021. "Speciation and bioavailability of mercury in sediments from Mokolo River, Limpopo Province, South Africa." Journal of Environmental Science and Health, Part A , no. : 1-11.

Review
Published: 13 May 2021 in International Journal of Environmental Analytical Chemistry
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Precious metals accumulated to high concentration spread across tailing dumps, mineralised soil and at many metal-processing facilities across the African continent. Currently, about 71% of the world’s deposits of platinum group metals (PGMs) are found in South Africa. The country produces about 60% of the world’s output of three of these precious metals namely; platinum, palladium and rhodium. Traditional mining technology is grossly insufficient to quantitatively recover all metals economically. Therefore, low concentrations of these valuable metals are often wasted away as leftovers – posing environmental menace to the general ecosystem via dissolved ‘associated-toxic metal leaching’ and run-offs. In the past few decades, the concept of phytomining to recover low concentration precious metals from mine tailings, has been investigated by various researchers inMexico, New Zeeland, Caledonia, Canada, United Kingdom and Australia. This review presents a synopsis of the reported precious metal phytomining studies developed on the laboratory scale, and/or in greenhouse or pilot scale as well as in the field, in the last two and half decades. A summary of work done so far as relating to the techno-economic assessment of precious metal phytomining is also presented. We have also taken the opportunity to specifically discuss the applications of the phytoextracted plant-based metal in catalysis and related fields – an area with great potential to support the catalyst market and its adjacent chemicals and pharmaceutical industries but has been less explored for its possible coupling with phytomining activities so as to augment the economic prospects of this mining method.

ACS Style

Babatunde J. Akinbile; Banothile C. E. Makhubela; Abayneh A. Ambushe. Phytomining of valuable metals: status and prospective-a review. International Journal of Environmental Analytical Chemistry 2021, 1 -21.

AMA Style

Babatunde J. Akinbile, Banothile C. E. Makhubela, Abayneh A. Ambushe. Phytomining of valuable metals: status and prospective-a review. International Journal of Environmental Analytical Chemistry. 2021; ():1-21.

Chicago/Turabian Style

Babatunde J. Akinbile; Banothile C. E. Makhubela; Abayneh A. Ambushe. 2021. "Phytomining of valuable metals: status and prospective-a review." International Journal of Environmental Analytical Chemistry , no. : 1-21.

Journal article
Published: 16 March 2021 in Physics and Chemistry of the Earth, Parts A/B/C
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The aim of this study was to conduct multi-elemental speciation of As(III), dimethylarsinic acid (DMA), monomethylarsenic acid (MMA), As(V) and Cr(VI) in water samples using high performance liquid chromatography coupled to inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) in a single analytical run. Chromatographic parameters, spectral interference identification, and elimination and the performance characteristics of the method were successfully optimized for quantification of As(III), DMA, MMA, As(V), Cr(VI) and Cr(III) in water samples. The percentage errors of 6.93–43.2% for identified potential interferences were eliminated by applying the inter-element mathematical correction method. The limit of detection (LOD) and limit of quantification (LOQ) of As species and Cr(VI) were varied from 0.040-0.298 μg L−1 and 0.133–2.98 μg L−1, respectively. The LOD and LOQ of total As, Cr and Pb determined using ICP-MS were ranged from 0.013-0.203 μg L−1 and 0.045–0.675 μg L−1, respectively. The accuracy of the method was confirmed by achieving the percentage recovery of 83.4% for As species, 90.2% for Cr(VI) and 110–118% for total concentrations of As, Cr and Pb using standard reference material for trace elements in water (SRM 1643f). Furthermore, the accuracy of the speciation analysis method was checked using the spiking and recovery studies and yielded percentage recoveries in the range of 78.3–95.4% for the analyte species. The quantities of species determined in water samples were in the range of 0.314–0.402 μg L−1 for As(III), 0.168–0.533 μg L−1 for DMA, 0.226–0.312 μg L−1 for MMA, 0.191–0.459 μg L−1 for As(V), 0.500–3.28 μg L−1 for Cr(VI) and 0.390–12.6 μg L−1 for Cr(III) in high-flow seasonal state of the river. In the low-flow seasonal state, concentrations varied from 0.314-0.391 μg L−1 for As(III), 0.05) at a 95% confidence level except for DMA. The nonpoint sources pollution such as atmospheric deposition of dust released from coal mining, power stations, sewage effluents discharge and agricultural activities are presumably the sources of potentially toxic elements in the Mokolo River.

ACS Style

Mokgehle R. Letsoalo; Messai A. Mamo; Abayneh A. Ambushe. Simultaneous quantitative speciation of selected toxic elements in water using high performance liquid chromatography coupled to inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). Physics and Chemistry of the Earth, Parts A/B/C 2021, 103011 .

AMA Style

Mokgehle R. Letsoalo, Messai A. Mamo, Abayneh A. Ambushe. Simultaneous quantitative speciation of selected toxic elements in water using high performance liquid chromatography coupled to inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). Physics and Chemistry of the Earth, Parts A/B/C. 2021; ():103011.

Chicago/Turabian Style

Mokgehle R. Letsoalo; Messai A. Mamo; Abayneh A. Ambushe. 2021. "Simultaneous quantitative speciation of selected toxic elements in water using high performance liquid chromatography coupled to inductively coupled plasma-mass spectrometry (HPLC-ICP-MS)." Physics and Chemistry of the Earth, Parts A/B/C , no. : 103011.

Article
Published: 18 June 2020 in Biological Trace Element Research
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Rooibos tea, scientific name Aspalathus linearis, is a popular tea grown in South Africa and consumed worldwide for its unique taste and presumed health benefits. There is a growing interest in using rooibos tea as a supplement for the deficiency of metallic nutrients in South Africa. In this study, the total concentrations of manganese (Mn) and zinc (Zn) in acid-digested tea leaves and the corresponding tea infusions were determined by inductively coupled plasma-mass spectrometry (ICP-MS) to estimate the contribution of rooibos tea consumption to the recommended daily allowance (RDA) of Mn and Zn in consumers. The accuracy of microwave-assisted acid digestion and tea infusion methods were checked by analyzing INCT-TL-1 tea leaves certified reference material (CRM) and samples spiked with standards, respectively. Both methods yielded quantitative percentage recoveries for Mn and Zn. Rooibos tea leaves and the corresponding infusions are composed of higher levels of Mn than Zn where 40.9 to 85.7 μg Mn/g and 4.15 to 12.2 μg Zn/g were found in digested tea leaves and 11.8 to 30.2 μg Mn/g and 1.51 to 4.59 μg Zn/g in tea infusions. These results indicate the contribution of about 1.0 to 3.2% Mn and 0.03 to 0.08% Zn in males approximately ≥ 9 years of age and 1.3 to 3.8% Mn and 0.04 to 0.11% Zn in females of the same age group as males of the RDA from drinking a cup of tea obtained by infusing a 2-g bag of rooibos tea.

ACS Style

Nombuzo Mabuza; Henok H. Kinfe; Taddese W. Godeto; Abayneh A. Ambushe. Estimated Contributions of Rooibos Tea to the Daily Manganese and Zinc Intakes Determined in Tea Leaves and Tea Infusions by Inductively Coupled Plasma-Mass Spectrometry. Biological Trace Element Research 2020, 199, 1145 -1152.

AMA Style

Nombuzo Mabuza, Henok H. Kinfe, Taddese W. Godeto, Abayneh A. Ambushe. Estimated Contributions of Rooibos Tea to the Daily Manganese and Zinc Intakes Determined in Tea Leaves and Tea Infusions by Inductively Coupled Plasma-Mass Spectrometry. Biological Trace Element Research. 2020; 199 (3):1145-1152.

Chicago/Turabian Style

Nombuzo Mabuza; Henok H. Kinfe; Taddese W. Godeto; Abayneh A. Ambushe. 2020. "Estimated Contributions of Rooibos Tea to the Daily Manganese and Zinc Intakes Determined in Tea Leaves and Tea Infusions by Inductively Coupled Plasma-Mass Spectrometry." Biological Trace Element Research 199, no. 3: 1145-1152.

Article
Published: 17 June 2020 in International Journal of Environmental Analytical Chemistry
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Chromium (Cr) can be either essential or carcinogenic depending on the chemical form. The aim of this study was to speciate Cr in water samples, collected from Blood and Mokolo Rivers, Limpopo Province. Water samples were collected from ten sampling sites from each river. The accuracy of the method was evaluated by employing standard reference material of trace elements in water (SRM 1643 f) before sample analysis. Total Cr and Cr(VI) in water samples were quantified using graphite furnace-atomic absorption spectrometry (GF-AAS). The concentrations of Cr in water samples collected from Blood and Mokolo Rivers were found in the range of 1.56 μg/L to 6.11 μg/L and 1.34 µg/L to 3.53 µg/L, respectively. A solid phase extraction (SPE) method based on chromabond NH2 column was used to determine Cr(VI) in water. In order to achieve separation of Cr(VI), the sample was pre-concentrated and passed through a conditioned chromabond NH2 column at a flow rate of 3 mL/min. Hexavalent Cr was selectively adsorbed onto the column and the contents were dried under vacuum. The retained Cr(VI) was subsequently eluted with two column volumes of 2 M HNO3 and diluted to a final volume of 10.0 mL. The limit of detection (LOD) was 0.105 µg/L and the percentage relative standard deviations were less than 10%. The validation of the procedure was performed by spiking standard solutions containing Cr(III) and Cr(VI) and the percentage recoveries were higher than 88%. The concentrations of Cr(VI) in Blood and Mokolo Rivers ranged from 0.13 µg/L to 1.99 µg/L and 0.13 µg/L to 0.55 µg/L, respectively. In Blood and Mokolo Rivers, although the concentrations of Cr(VI) are low, their values suggest a link with the industrial and agricultural activities in the area.

ACS Style

Conny P. Mokgohloa; Mary S. Thomas; Ntebogeng S. Mokgalaka; Abayneh A. Ambushe. Speciation of inorganic chromium in river water by graphite furnace-atomic absorption spectrometry after chromabond NH2 column based solid phase extraction. International Journal of Environmental Analytical Chemistry 2020, 1 -16.

AMA Style

Conny P. Mokgohloa, Mary S. Thomas, Ntebogeng S. Mokgalaka, Abayneh A. Ambushe. Speciation of inorganic chromium in river water by graphite furnace-atomic absorption spectrometry after chromabond NH2 column based solid phase extraction. International Journal of Environmental Analytical Chemistry. 2020; ():1-16.

Chicago/Turabian Style

Conny P. Mokgohloa; Mary S. Thomas; Ntebogeng S. Mokgalaka; Abayneh A. Ambushe. 2020. "Speciation of inorganic chromium in river water by graphite furnace-atomic absorption spectrometry after chromabond NH2 column based solid phase extraction." International Journal of Environmental Analytical Chemistry , no. : 1-16.

Articles
Published: 16 September 2019 in Journal of Environmental Science and Health, Part A
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The presence of polycyclic aromatic hydrocarbons (PAHs) in the environment is of major concern since some of these compounds are highly persistent, toxic (causing cancer) and wide spread pollutants. The objective of this study was to evaluate the levels of PAHs in sediment samples collected from Blood and Mokolo Rivers in Limpopo Province, South Africa. The PAHs in sediments were extracted using optimized microwave-assisted extraction (MAE) method. The quantification of sixteen (16) PAHs in sediments was done by gas chromatography-flame ionization detector (GC-FID). The levels of PAHs recorded in sediment samples from Blood River ranged between 0.015 and 3.25 mg kg−1. The concentrations of PAHs obtained in sediments from Mokolo River (0.047 to 52.7 mg kg−1) were higher than those recorded in sediments from Blood River. The PAHs ratios indicated that both pyrogenic and petrogenic could be the sources of these compounds in both rivers. Toxic equivalency factors (TEFs) and benzo(a)pyrene equivalent (BaPE) were used to estimate the potential human health risk of PAHs in quantitative terms. The assessment of ecotoxicological risk indicated that the sediment samples collected from Mokolo River are at high toxicity risk while sediments from Blood River are at low sediment toxicity risk.

ACS Style

Tumelo M. Mogashane; Munyaradzi Mujuru; Robert I. McCrindle; Abayneh A. Ambushe. Quantification, source apportionment and risk assessment of polycyclic aromatic hydrocarbons in sediments from Mokolo and Blood Rivers in Limpopo Province, South Africa. Journal of Environmental Science and Health, Part A 2019, 55, 71 -81.

AMA Style

Tumelo M. Mogashane, Munyaradzi Mujuru, Robert I. McCrindle, Abayneh A. Ambushe. Quantification, source apportionment and risk assessment of polycyclic aromatic hydrocarbons in sediments from Mokolo and Blood Rivers in Limpopo Province, South Africa. Journal of Environmental Science and Health, Part A. 2019; 55 (1):71-81.

Chicago/Turabian Style

Tumelo M. Mogashane; Munyaradzi Mujuru; Robert I. McCrindle; Abayneh A. Ambushe. 2019. "Quantification, source apportionment and risk assessment of polycyclic aromatic hydrocarbons in sediments from Mokolo and Blood Rivers in Limpopo Province, South Africa." Journal of Environmental Science and Health, Part A 55, no. 1: 71-81.

Articles
Published: 03 May 2019 in Journal of Environmental Science and Health, Part A
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The multi-walled carbon nanotubes-branched polyethyleneimine (MWCNTs-BPEI) adsorbent composite material was employed to separate and pre-concentrate As(V) in water samples. The characterization of MWCNTs-BPEI by X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy showed successful modification of the composite. The MWCNTs-BPEI composite exhibited selective retention of As(V) in the presence of As(III) in water samples of pH 7 using 40 mg of composite as adsorbent. The pre-concentrated As(V) was quantified using inductively coupled plasma-mass spectrometry (ICP-MS). A limit of detection (LOD) of 0.0537 µg L−1 and limit of quantification (LOQ) of 0.179 µg L−1 were achieved along with pre-concentration factor of 23.3. A percentage recovery of 81.0% confirm the accuracy of the method. The As(V) concentrations in water were in the range of 0.0612–3.65 µg L−1. The As(V) concentrations determined using solid-phase extraction (SPE) procedure were in good agreement with the concentrations obtained using high performance liquid chromatography hyphenated to inductively coupled mass-mass spectrometry (HPLC hyphenated to ICP-MS).

ACS Style

Mokgehle R. Letsoalo; Taddese W. Godeto; Takalani Magadzu; Abayneh A. Ambushe. Selective speciation of inorganic arsenic in water using nanocomposite based solid-phase extraction followed by inductively coupled plasma-mass spectrometry detection. Journal of Environmental Science and Health, Part A 2019, 54, 924 -932.

AMA Style

Mokgehle R. Letsoalo, Taddese W. Godeto, Takalani Magadzu, Abayneh A. Ambushe. Selective speciation of inorganic arsenic in water using nanocomposite based solid-phase extraction followed by inductively coupled plasma-mass spectrometry detection. Journal of Environmental Science and Health, Part A. 2019; 54 (9):924-932.

Chicago/Turabian Style

Mokgehle R. Letsoalo; Taddese W. Godeto; Takalani Magadzu; Abayneh A. Ambushe. 2019. "Selective speciation of inorganic arsenic in water using nanocomposite based solid-phase extraction followed by inductively coupled plasma-mass spectrometry detection." Journal of Environmental Science and Health, Part A 54, no. 9: 924-932.

Environmental analysis
Published: 07 May 2018 in Analytical Letters
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The Mokolo River is disposed to environmental contaminants such as arsenic (As) due to its proximity to several anthropogenic activities. Speciation of As in water and sediment samples from Mokolo River is crucial to evaluate the level and distribution of As in the river and underlying sediment since toxicity depends on its chemical forms. In this study, As species in water and sediment were determined by developing a new method for sediment extraction. Effective microwave-assisted extraction of As species in sediment samples was achieved using 0.3 M (NH4)2HPO4 and 50 mM EDTA, which showed no species interconversion during extraction. The chromatographic separation and detection of As(III), dimethylarsinic acid (DMA), monomethylarsonic acid, and As(V) in water and sediment samples were achieved by coupling to high-performance liquid chromatography to inductively coupled plasma mass spectrometry. Baseline separation of four As species was achieved in 12 min using gradient elution with 10 and 60 mM NH4NO3 at pH 8.7 as the mobile phase. The analytical figures of merit and validation of analytical procedures were assessed and adequate performance and percentage recoveries ranging from 81.1 to 102% for water samples and 73.0–92.0% for sediments were achieved. The As species concentration in water and sediment samples was found to be in the range of 0.304–4.99 µg L−1 and 74.0–92.0 ng g−1, respectively. DMA was not detected in both water and sediment samples.

ACS Style

Mokgehle R. Letsoalo; Taddese W. Godeto; Takalani Magadzu; Abayneh A. Ambushe. Quantitative Speciation of Arsenic in Water and Sediment Samples from the Mokolo River in Limpopo Province, South Africa. Analytical Letters 2018, 51, 2763 -2777.

AMA Style

Mokgehle R. Letsoalo, Taddese W. Godeto, Takalani Magadzu, Abayneh A. Ambushe. Quantitative Speciation of Arsenic in Water and Sediment Samples from the Mokolo River in Limpopo Province, South Africa. Analytical Letters. 2018; 51 (17):2763-2777.

Chicago/Turabian Style

Mokgehle R. Letsoalo; Taddese W. Godeto; Takalani Magadzu; Abayneh A. Ambushe. 2018. "Quantitative Speciation of Arsenic in Water and Sediment Samples from the Mokolo River in Limpopo Province, South Africa." Analytical Letters 51, no. 17: 2763-2777.

Journal article
Published: 30 April 2018 in Journal of Environmental Science and Health, Part A
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Environmental monitoring of the levels of potentially toxic metals is of importance because of possible adverse effects on living species. This study was conducted to assess the levels of Cd, Cr, Cu, Hg, Mn, Pb, U and V in water, sediment and peat samples collected from the region of Wonderfonteinspruit. Water samples were simply filtered and acidified with HNO3 prior to analysis. Sediment and peat were oven-dried, ground, sieved and mineralised using a microwave digestion system. Concentrations of the selected elements in all samples were determined by inductively coupled plasma-mass spectrometry. A Zeeman mercury analyser was also used for quantification of Hg in the same sediment and peat samples. The method validation was carried out using SRM 1643e water and BCR 320R sediment certified reference materials. The results showed no significant difference at 95% level of confidence between the certified and measured values after using the Student's t-test. The levels of Cd, Cr, Cu, Pb, V and U found in rivers and dams were lower than the tentative South African water quality range guideline for domestic and irrigation purposes. However, water from dams and certain rivers was unsuitable for irrigation and domestic use.

ACS Style

Ntumba C. Nsaka; Robert I. McCrindle; Abayneh A. Ambushe. Levels of potentially toxic metals in water, sediment and peat from Wonderfonteinspruit, North West Province, South Africa. Journal of Environmental Science and Health, Part A 2018, 53, 907 -914.

AMA Style

Ntumba C. Nsaka, Robert I. McCrindle, Abayneh A. Ambushe. Levels of potentially toxic metals in water, sediment and peat from Wonderfonteinspruit, North West Province, South Africa. Journal of Environmental Science and Health, Part A. 2018; 53 (10):907-914.

Chicago/Turabian Style

Ntumba C. Nsaka; Robert I. McCrindle; Abayneh A. Ambushe. 2018. "Levels of potentially toxic metals in water, sediment and peat from Wonderfonteinspruit, North West Province, South Africa." Journal of Environmental Science and Health, Part A 53, no. 10: 907-914.

Original articles
Published: 01 December 2014 in Journal of Environmental Science and Health, Part A
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Microwave-assisted acid digestion and modified aqua regia (HNO3:HCl:HF:H3BO3) leaching techniques were used for the determination of 15 potentially toxic elements (V, Cr, Fe, Mn, Co, Ni, Cu, Zn, As, Se, Ag, Cd, Sn, Hg and Pb) in sediment samples from Lake Awassa and Lake Ziway, Ethiopia. The digests were subsequently analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-optical emission spectrometry (ICP-OES). Mercury was directly determined in the solid samples using an elemental mercury analyzer. The precision and accuracy of the digestion procedures were verified using certified reference materials. The experimental results were in good agreement with the certified values (P < 0.05) and the recoveries were quantitative (>90%). The average relative standard deviations were below 10%. There is significant correlation between the two lakes at the 0.01 level (2-tailed). Using the sediment quality guidelines, both lakes are heavily polluted with Zn and some of the sites are heavily polluted with Cu, Ni and Pb. Based on effect range low (ERL) - effect range medium (ERM), in both lakes for Ag were greater than the ERM, indicating that the areas could be toxic to aquatic organisms, while for Cr, Cu, As and Hg the values were less than ERL.

ACS Style

Kebede Nigussie Mekonnen; Abayneh A. Ambushe; Bhagwan S. Chandravanshi; Mesfin Redi-Abshiro; Robert I. McCrindle. Occurrence, distribution, and ecological risk assessment of potentially toxic elements in surface sediments of Lake Awassa and Lake Ziway, Ethiopia. Journal of Environmental Science and Health, Part A 2014, 50, 90 -99.

AMA Style

Kebede Nigussie Mekonnen, Abayneh A. Ambushe, Bhagwan S. Chandravanshi, Mesfin Redi-Abshiro, Robert I. McCrindle. Occurrence, distribution, and ecological risk assessment of potentially toxic elements in surface sediments of Lake Awassa and Lake Ziway, Ethiopia. Journal of Environmental Science and Health, Part A. 2014; 50 (1):90-99.

Chicago/Turabian Style

Kebede Nigussie Mekonnen; Abayneh A. Ambushe; Bhagwan S. Chandravanshi; Mesfin Redi-Abshiro; Robert I. McCrindle. 2014. "Occurrence, distribution, and ecological risk assessment of potentially toxic elements in surface sediments of Lake Awassa and Lake Ziway, Ethiopia." Journal of Environmental Science and Health, Part A 50, no. 1: 90-99.