Evidences on As(III) and As(V) interaction with iron(III) oxides: Hematite and goethite

Arsenic, which is ubiquitous in nature, was found associated with iron oxides in soils and sediments. Our interest was to utilize the same mechanism for the sorptive removal of arsenic from groundwater. The iron(III) oxides: hematite, goethite, were synthesized, characterized and sorption studies of...

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Bibliographic Details
Published in:Journal of environmental science and health. Part A, Toxic/hazardous substances & environmental engineering Toxic/hazardous substances & environmental engineering, 2021-07, Vol.56 (9), p.1007-1018
Main Authors: Ajith, Nicy, Satpati, A. K., Debnath, A. K., Swain, K. K.
Format: Article
Language:English
Subjects:
arsenate
Arsenic
arsenite
Electrochemistry
Goethite
Groundwater
Hematite
Iron oxides
Mechanism of sorption
Oxidation
Oxides
Photoelectron spectroscopy
Photoelectrons
Pollutant removal
Redox reactions
Sediments
Sorbents
Sorption
Species
X ray photoelectron spectroscopy
XPS
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Summary:Arsenic, which is ubiquitous in nature, was found associated with iron oxides in soils and sediments. Our interest was to utilize the same mechanism for the sorptive removal of arsenic from groundwater. The iron(III) oxides: hematite, goethite, were synthesized, characterized and sorption studies of arsenic [As(III) and As(V)] were carried out in batch mode. For studying the evidence of the interaction between arsenic and iron oxide during the process of sorption, a new electrochemical method was developed. Differential pulse voltammetry (DPV) study indicated that the sorbed arsenic species is redox active on the surface of the sorbent. X-ray photoelectron spectroscopy (XPS) measurement was performed for confirmation of the changes occurring to the oxidation states of iron as well as arsenic after the sorption. XPS studies confirmed that the behavior of arsenic species on hematite/goethite was similar and occurs via a partial redox reaction. During sorption of As(III), a partial oxidation occurs resulting in As(V) species, simultaneously the Fe(III) present in the iron oxide gets reduced to Fe(II). However, during the sorption of As(V), there occurs a Fe(II) oxidation followed by As(V) reduction. Based on the results, a mechanistic scheme for sorption of arsenic on iron(III) oxides as sorbents was proposed.
ISSN:1093-4529
1532-4117
DOI:10.1080/10934529.2021.1959173