Effects of dimethylarsenate coprecipitation with ferrihydrite on Fe(II)-induced mineral transformation and the release of dimethylarsenate

Yi Chen; Yueyang Quan; Yipu Liu; Meng Yuan; Jiaqi Wang; Chuan Chen; Chuanqin Huang; Xiaoyu Fang; Jing Zhang; Xionghan Feng; Wenfeng Tan; Jiangshan Li; Hui Yin

doi:10.1016/j.envpol.2024.125593

Effects of dimethylarsenate coprecipitation with ferrihydrite on Fe(II)-induced mineral transformation and the release of dimethylarsenate

Environ Pollut. 2024 Dec 27:367:125593. doi: 10.1016/j.envpol.2024.125593. Online ahead of print.

Authors

Yi Chen¹, Yueyang Quan¹, Yipu Liu¹, Meng Yuan¹, Jiaqi Wang¹, Chuan Chen², Chuanqin Huang³, Xiaoyu Fang¹, Jing Zhang⁴, Xionghan Feng¹, Wenfeng Tan¹, Jiangshan Li⁵, Hui Yin⁶

Affiliations

¹ Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture and Rural Affairs, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, College of Resources and Environment, Wuhan, 430070, China.
² Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
³ Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture and Rural Affairs, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, College of Resources and Environment, Wuhan, 430070, China. Electronic address: hcq@mail.hzau.edu.cn.
⁴ Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100039, China.
⁵ State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, 430071, China.
⁶ Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture and Rural Affairs, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, College of Resources and Environment, Wuhan, 430070, China. Electronic address: yinhui666@mail.hzau.edu.cn.

PMID: 39734042
DOI: 10.1016/j.envpol.2024.125593

Abstract

Organoarsenicals are toxic pollutants of global concern, and their environmental geochemical behavior might be greatly controlled by iron (Fe) (hydr)oxides through coprecipitation, which is rarely investigated. Here, the effects of the incorporation of dimethylarsenate (DMAs(V)), a typical organoarsenical, into the ferrihydrite (Fh) structure on the mineral physicochemical properties and Fe(II)-induced phase transformation of DMAs(V)-Fh coprecipitates with As/Fe molar ratios up to 0.0876 ± 0.0036 under anoxic conditions and the accompanying DMAs(V) release were investigated. The presence of DMAs(V) during Fh formation gradually decreases the mineral crystallinity. With increasing DMAs(V) content, the specific surface areas of the coprecipitates are decreased owing to particle aggregation, while the micropore sizes are negligible changed. Fourier transformed infrared (FTIR) and As K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy show that, part of DMAs(V) binds to Fh surfaces in the coprecipitates by forming bidentate binuclear inner-sphere complexes through As-O-Fe bonds. During the reaction of the coprecipitate with 1 mM Fe(II) for 336 h, DMAs(V) inhibits the Fh transformation to goethite. No goethite forms at pH 4; at pH 7 low content of DMAs(V) hinders the further conversion of lepidocrocite to goethite, while high content of DMAs(V) completely inhibits goethite formation. DMAs(V) in the coprecipitate is continuously released into the solution, with the released proportion being generally increased with the increase of DMAs(V) content, pH and Fe(II) addition, probably owing to the desorption of weak inner- and outer-sphere DMAs(V) complexes bound on the Fh surfaces upon the Fh aging and transformation to lepidocrocite and goethite. These results provide deep insights into the fate and mobility of organoarsenical pollutants mediated by Fe (hydr)oxides in natural environments, and help design effective and ecofriendly remediation strategies for As polluted soils and sediments.

Keywords: Coprecipitation; Desorption; Iron (hydr)oxides; Mineral transformation; Organoarsenicals.