Fate of oxalic-acid-intervened arsenic during Fe(II)-induced transformation of As(V)-bearing jarosite

Xiaohu Jin; Xiaofei Li; Chuling Guo; Mengge Jiang; Qian Yao; Guining Lu; Zhi Dang

doi:10.1016/j.scitotenv.2020.137311

Fate of oxalic-acid-intervened arsenic during Fe(II)-induced transformation of As(V)-bearing jarosite

Sci Total Environ. 2020 Jun 1:719:137311. doi: 10.1016/j.scitotenv.2020.137311. Epub 2020 Feb 13.

Authors

Xiaohu Jin¹, Xiaofei Li¹, Chuling Guo², Mengge Jiang¹, Qian Yao¹, Guining Lu¹, Zhi Dang³

Affiliations

¹ School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, PR China.
² School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, PR China. Electronic address: clguo@scut.edu.cn.
³ School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, PR China. Electronic address: chzdang@scut.edu.cn.

PMID: 32120095
DOI: 10.1016/j.scitotenv.2020.137311

Abstract

Jarosite is a metastable Fe(III)-oxyhydroxysulfate mineral that can act as an excellent scavenger for arsenic (As) in acid sulfate soils (ASSs) and in areas polluted by acid mine drainage (AMD). The Fe(II)-induced transformation of jarosite can influence the As mobility in reducing soil and sediment systems. Although organic acids are prevalent in these environments, their influence on the behavior of As during the Fe(II)-induced transformation of jarosite is yet to be fully understood. In this study, we investigated the effects of oxalic acid on the partitioning of As into dissolved, adsorbed, poorly crystalline, and residual phases during the Fe(II)-induced transformation of As(V)-bearing jarosite at pH 5.5 and 1 mM Fe(II) concentration. The results demonstrated that jarosite frequently transformed to lepidocrocite in treatments without oxalic acid or with low oxalic acid (0.1 mM), and As was typically redistributed in the surface-bound exchangeable and residual phases. While a high concentration of oxalic acid (1 mM) retarded the transformation of jarosite and produced goethite as the primary end product, it also changed the Fe(II)-induced transformation pathway and drove most As into the residual phase (approximately 92%). The results indicated that oxalic acid exerts a significant influence on the partitioning and speciation of As during the above-mentioned transformation. X-ray photo electron spectroscopy analysis of the reaction products also revealed that As(V) may be still the dominant redox species. Overall, this study provides critical information for understanding the fate of As during the transformation of secondary minerals under complex influencing factors, thereby assisting in more accurately predicting the geochemical cycling of As in natural systems.

Keywords: Arsenic; Fe(II)-induced transformation; Jarosite; Oxalic acid; Secondary minerals.