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Eikelboom M, Wang Y, Portlock G, Gourain A, Gardner J, Bullen J, Lewtas P, Carriere M, Alvarez A, Kumar A, O'Prey S, Tölgyes T, Omanović D, Bhowmick S, Weiss D, Salaun P. Voltammetric determination of inorganic arsenic in mildly acidified (pH 4.7) groundwaters from Mexico and India. Anal Chim Acta 2023; 1276:341589. [PMID: 37573093 DOI: 10.1016/j.aca.2023.341589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 06/19/2023] [Accepted: 07/04/2023] [Indexed: 08/14/2023]
Abstract
Routine monitoring of inorganic arsenic in groundwater using sensitive, reliable, easy-to-use and affordable analytical methods is integral to identifying sources, and delivering appropriate remediation solutions, to the widespread global issue of arsenic pollution. Voltammetry has many advantages over other analytical techniques, but the low electroactivity of arsenic(V) requires the use of either reducing agents or relatively strong acidic conditions, which both complicate the analytical procedures, and require more complex material handling by skilled operators. Here, we present the voltammetric determination of total inorganic arsenic in conditions of near-neutral pH using a new commercially available 25 μm diameter gold microwire (called the Gold Wirebond), which is described here for the first time. The method is based on the addition of low concentrations of permanganate (10 μM MnO4-) which fulfils two roles: (1) to ensure that all inorganic arsenic is present as arsenate by chemically oxidising arsenite to arsenate and, (2) to provide a source of manganese allowing the sensitive detection of arsenate by anodic stripping voltammetry at a gold electrode. Tests were carried out in synthetic solutions of various pH (ranging from 4.7 to 9) in presence/absence of chloride. The best response was obtained in 0.25 M chloride-containing acetate buffer resulting in analytical parameters (limit of detection of 0.28 μg L-1 for 10 s deposition time, linear range up to 20 μg L-1 and a sensitivity of 63.5 nA ppb-1. s-1) better than those obtained in acidic conditions. We used this new method to measure arsenic concentrations in contrasting groundwaters: the reducing, arsenite-rich groundwaters of India (West Bengal and Bihar regions) and the oxidising, arsenate-rich groundwaters of Mexico (Guanajuato region). Very good agreement was obtained in all groundwaters with arsenic concentrations measured by inductively coupled plasma-mass spectrometry (slope = +1.029, R2 = 0.99). The voltammetric method is sensitive, faster than other voltammetric techniques for detection of arsenic (typically 10 min per sample including triplicate measurements and 2 standard additions), easier to implement than previous methods (no acidic conditions, no chemical reduction required, reproducible sensor, can be used by non-voltammetric experts) and could enable cheaper groundwater surveying campaigns with in-the-field analysis for quick data reporting, even in remote communities.
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Affiliation(s)
- Martijn Eikelboom
- School of Environmental Sciences, University of Liverpool, 4 Brownlow Street, L69 3GP, Liverpool, UK.
| | - Yaxuan Wang
- School of Environmental Sciences, University of Liverpool, 4 Brownlow Street, L69 3GP, Liverpool, UK
| | - Gemma Portlock
- School of Environmental Sciences, University of Liverpool, 4 Brownlow Street, L69 3GP, Liverpool, UK
| | - Arthur Gourain
- School of Environmental Sciences, University of Liverpool, 4 Brownlow Street, L69 3GP, Liverpool, UK
| | - Joseph Gardner
- School of Environmental Sciences, University of Liverpool, 4 Brownlow Street, L69 3GP, Liverpool, UK
| | - Jay Bullen
- Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Paul Lewtas
- School of Science, Edith Cowan University, 270 Joondalup Drive, Joondalup, Western Australia, 6027, Australia
| | - Matthieu Carriere
- Caminos de Agua, José María Correa 23A, Colonia Santa Cecilia, 37727, San Miguel de Allende, Gto, Mexico
| | - Alexandra Alvarez
- Caminos de Agua, José María Correa 23A, Colonia Santa Cecilia, 37727, San Miguel de Allende, Gto, Mexico
| | - Arun Kumar
- Mahavir Cancer Sansthan and Research Centre, Phulwarisharif, Patna, 801505, Bihar, India
| | | | | | - Dario Omanović
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička 54, 10000, Zagreb, Croatia
| | - Subhamoy Bhowmick
- Kolkata Zonal Center CSIR-National Environmental Engineering Research Institute (NEERI), Kolkata, West Bengal, 700107, India
| | - Dominik Weiss
- Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Pascal Salaun
- School of Environmental Sciences, University of Liverpool, 4 Brownlow Street, L69 3GP, Liverpool, UK.
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Roh T, Knappett PSK, Han D, Ludewig G, Kelly KM, Wang K, Weyer PJ. Characterization of Arsenic and Atrazine Contaminations in Drinking Water in Iowa: A Public Health Concern. Int J Environ Res Public Health 2023; 20:5397. [PMID: 37048011 PMCID: PMC10094102 DOI: 10.3390/ijerph20075397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 03/29/2023] [Accepted: 04/03/2023] [Indexed: 06/19/2023]
Abstract
Arsenic and atrazine are two water contaminants of high public health concern in Iowa. The occurrence of arsenic and atrazine in drinking water from Iowa's private wells and public water systems was investigated over several decades. In this study, the percentages of detection and violation of regulations were compared over region, season, and water source, and factors affecting the detection and concentration of arsenic and atrazine were analyzed using a mixed-effects model. Atrazine contamination in drinking water was found to vary by region, depending on agricultural usage patterns and hydrogeological features. The annual median atrazine levels of all public water systems were below the drinking water standard of 3 ppb in 2001-2014. Around 40% of public water systems contained arsenic at levels > 1 ppb in 2014, with 13.8% containing arsenic at levels of 5-10 ppb and 2.6% exceeding 10 ppb. This unexpected result highlights the ongoing public health threat posed by arsenic in drinking water in Iowa, emphasizing the need for continued monitoring and mitigation efforts to reduce exposure and associated health risks. Additionally, an atrazine metabolite, desethylatrazine, should be monitored to obtain a complete account of atrazine exposure and possible health effects.
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Affiliation(s)
- Taehyun Roh
- Department of Epidemiology and Biostatistics, Texas A&M University, College Station, TX 77843, USA
| | - Peter S. K. Knappett
- Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA
| | - Daikwon Han
- Department of Epidemiology and Biostatistics, Texas A&M University, College Station, TX 77843, USA
| | - Gabriele Ludewig
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, IA 52242, USA
- Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA 52242, USA
| | - Kevin M. Kelly
- Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA 52242, USA
| | - Kai Wang
- Department of Biostatistics, University of Iowa, Iowa City, IA 52242, USA
| | - Peter J. Weyer
- Center for Health Effects of Environmental Contamination, University of Iowa, Iowa City, IA 52242, USA
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Bullen JC, Heiba HF, Kafizas A, Weiss DJ. Parasitic Light Absorption, Rate Laws and Heterojunctions in the Photocatalytic Oxidation of Arsenic(III) Using Composite TiO 2 /Fe 2 O 3. Chemistry 2022; 28:e202104181. [PMID: 35114042 PMCID: PMC9306794 DOI: 10.1002/chem.202104181] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Indexed: 11/08/2022]
Abstract
Composite photocatalyst‐adsorbents such as TiO2/Fe2O3 are promising materials for the one‐step treatment of arsenite contaminated water. However, no previous study has investigated how coupling TiO2 with Fe2O3 influences the photocatalytic oxidation of arsenic(III). Herein, we develop new hybrid experiment/modelling approaches to study light absorption, charge carrier behaviour and changes in the rate law of the TiO2/Fe2O3 system, using UV‐Vis spectroscopy, transient absorption spectroscopy (TAS), and kinetic analysis. Whilst coupling TiO2 with Fe2O3 improves total arsenic removal by adsorption, oxidation rates significantly decrease (up to a factor of 60), primarily due to the parasitic absorption of light by Fe2O3 (88 % of photons at 368 nm) and secondly due to changes in the rate law from disguised zero‐order kinetics to first‐order kinetics. Charge transfer across this TiO2‐Fe2O3 heterojunction is not observed. Our study demonstrates the first application of a multi‐adsorbate surface complexation model (SCM) towards describing As(III) oxidation kinetics which, unlike Langmuir‐Hinshelwood kinetics, includes the competitive adsorption of As(V). We further highlight the importance of parasitic light absorption and catalyst fouling when designing heterogeneous photocatalysts for As(III) remediation.
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Affiliation(s)
- Jay C Bullen
- Department of Earth Science and Engineering, Faculty of Engineering Imperial College London, London, SW7 2BX, UK.,Department of Chemistry, White City Campus Imperial College London, London, W12 OBZ, UK.,London Centre for Nanotechnology, London, SW7 2AZ, UK
| | - Hany F Heiba
- Department of Earth Science and Engineering, Faculty of Engineering Imperial College London, London, SW7 2BX, UK.,Department of Chemistry, White City Campus Imperial College London, London, W12 OBZ, UK.,London Centre for Nanotechnology, London, SW7 2AZ, UK.,Marine Chemistry Department, Environmental Division National Institute of Oceanography and Fisheries, NIOF), Egypt
| | - Andreas Kafizas
- Department of Chemistry, White City Campus Imperial College London, London, W12 OBZ, UK.,The Grantham Institute, Faculty of Natural Sciences Imperial College London, London, SW7 2AZ, UK
| | - Dominik J Weiss
- Department of Earth Science and Engineering, Faculty of Engineering Imperial College London, London, SW7 2BX, UK.,Civil and Environmental Engineering, E-Quad, Princeton University, Princeton, USA
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