Aldmour, ST, Burke, IT, Bray, AW orcid.org/0000-0001-5399-6647 et al. (6 more authors) (2019) Abiotic reduction of Cr(VI) by humic acids derived from peat and lignite: kinetics and removal mechanism. Environmental Science and Pollution Research, 26 (5). pp. 4717-4729. ISSN 0944-1344
Abstract
Hexavalent chromium contamination of groundwater is a worldwide problem caused by anthropogenic and natural processes. We report the rate of Cr(VI) removal by two humic acids (extracted from Miocene age lignite and younger peat soil) in aqueous suspensions across a pH range likely to be encountered in terrestrial environments. Cr(VI) was reduced to Cr(III) in a first order reaction with respect Cr(VI) concentration, but exhibited a partial order (~0.5) with respect to [H+]. This reaction was more rapid with the peat humic acid, where Cr(VI) reduction was observed at all pH values investigated (3.7 ≤ pH ≤ 10.5). 13C NMR and pyrolysis GC-MS spectroscopy indicate that the reaction results in loss of substituted phenolic moieties and hydroxyl groups from the humic acids. X-ray absorption spectroscopy indicated that at all pH values the resulting Cr(III) was associated with the partially degraded humic acid in an inner sphere adsorption complex. The reaction mechanism is likely to be controlled by ester formation between Cr(VI) and phenolic/hydroxyl moieties, as this initial step is rapid in acidic systems but far less favorable in alkaline conditions. Our findings highlight the potential of humic acid to reduce and remove Cr(VI) from solution in a range of environmental conditions.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. |
Keywords: | Humic substances; Humic acids; Chromium; Contaminated Land; Groundwater |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemical & Process Engineering (Leeds) The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Civil Engineering (Leeds) The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Earth Surface Science Institute (ESSI) (Leeds) The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Soft Matter Physics (Leeds) |
Funding Information: | Funder Grant number NERC NE/L01405X/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 03 Dec 2018 11:02 |
Last Modified: | 28 Feb 2019 10:00 |
Status: | Published |
Publisher: | Springer Berlin Heidelberg |
Identification Number: | 10.1007/s11356-018-3902-1 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:139450 |
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