Effect of iron oxide reductive dissolution on the transformation and immobilization of arsenic in soils: New insights from X-ray photoelectron and X-ray absorption spectroscopy

• Published in: Journal of hazardous materials Vol. 279; pp. 212 - 219
• Main Authors: Fan, Jian-Xin, Wang, Yu-Jun, Liu, Cun, Wang, Li-Hua, Yang, Ke, Zhou, Dong-Mei, Li, Wei, Sparks, Donald L.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 30.08.2014; Elsevier
• Subjects: Adsorption; Applied sciences; Arsenic - chemistry; As(III); As(V); Chemical engineering; Continental surface waters; Dissolution; Exact sciences and technology; Ferric Compounds - chemistry; Immobilization; Iron oxides; Natural water pollution; Oxidation-Reduction; Photoelectron Spectroscopy; Pollution; Reductive dissolution; Soil Pollutants - chemistry; Soils; Solubility; Sorption; Speciation; Synchrotrons; Transformations; Water treatment and pollution; X-Ray Absorption Spectroscopy; X-rays; XAS; As(V); XAS; Iron oxides; Reductive dissolution; As(III); XANES spectrometry; Arsenic; X ray fluorescence; Immobilization; Batchwise; Wetland; Coprecipitation; Speciation; Cartography; Arsenates; Pollutant behavior; Iron II; Dissolution; Arsenites; Sorption; Iron III; X ray absorption spectrometry; Adsorption; Surface water; X ray absorption
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2014.06.079

•Immobility and transformation of As on different Eh soils were investigated.•μ-XRF, XANES, and XPS were used to gain As distribution and speciation in soil.•Sorption capacity of As on anaerobic soil was much higher than that on oxic soil.•Fe oxides reductive dissolution is a key factor for As sorption and transformation. The geochemical behavior and speciation of arsenic (As) in paddy soils is strongly controlled by soil redox conditions and the sequestration by soil iron oxyhydroxides. Hence, the effects of iron oxide reductive dissolution on the adsorption, transformation and precipitation of As(III) and As(V) in soils were investigated using batch experiments and synchrotron based techniques to gain a deeper understanding at both macroscopic and microscopic scales. The results of batch sorption experiments revealed that the sorption capacity of As(V) on anoxic soil was much higher than that on control soil. Synchrotron based X-ray fluorescence (μ-XRF) mapping studies indicated that As was heterogeneously distributed and was mainly associated with iron in the soil. X-ray absorption near edge structure (XANES), micro-X-ray absorption near edge structure (μ-XANES) and X-ray photoelectron spectroscopy (XPS) analyses revealed that the primary speciation of As in the soil is As(V). These results further suggested that, when As(V) was introduced into the anoxic soil, the rapid coprecipitation of As(V) with ferric/ferrous ion prevented its reduction to As(III), and was the main mechanism controlling the immobilization of As. This research could improve the current understanding of soil As chemistry in paddy and wetland soils.