title: Remediation of arsenic contaminated soil by coupling oxalate washing with subsequent ZVI/Air treatment.
abstract: The application of a novel coupled process with oxalate washing and subsequent zero-valent iron (ZVI)/Air treatment for remediation of arsenic contaminated soil was investigated in the present study. Oxalate is biodegradable and widely present in the environment. With addition of 0.1 mol L(-1) oxalate under circumneutral condition, 83.7% and 52.6% of arsenic could be removed from a spiked kaolin and an actual contaminated soil respectively. Much more oxalate adsorption on the actual soil was attributed to the higher soil organic matter and clay content. Interestingly, oxalate retained in the washing effluent could act as an organic ligand to promote the oxidation efficiency of ZVI/Air at near neutral pH. Compared with the absence of oxalate, much more As(III) was oxidized. Arsenic was effectively adsorbed on iron (hydr)oxides as the consumption of oxalate and the increase of pH value. For the actual soil washing effluent, about 94.9% of total arsenic was removed after 120 min's treatment without pH adjustment. It has been demonstrated that As(V) was the dominant arsenic speciation adsorbed on iron (hydr)oxides. This study provides a promising alternative for remediation of arsenic contaminated soil in view of its low cost and environmental benign.
authors.affiliation: Faculty of Resources and Environmental Science, Hubei University, Wuhan 430062, PR China.
authors.forename: Menghua
authors.initials: M
authors.lastname: Cao
authors.affiliation: Environmental Science Research Institution, College of Environment Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, PR China.
authors.forename: Yuanyao
authors.initials: Y
authors.lastname: Ye
authors.affiliation: Environmental Science Research Institution, College of Environment Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, PR China. Electronic address: chenjing@mail.hust.edu.cn.
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.affiliation: Environmental Science Research Institution, College of Environment Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, PR China. Electronic address: hust-esri2009@hotmail.com.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Lu
mesh_terms: D000327:Adsorption; D001151:Arsenic / Q000032:analysis* / Q000737:chemistry; D052918:Environmental Restoration and Remediation / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D010070:Oxalates / Q000737:chemistry*; D010084:Oxidation-Reduction; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry
chemical_list: D010070:Oxalates; D012987:Soil; D012989:Soil Pollutants; D007501:Iron; D001151:Arsenic
keywords: Adsorption; Arsenic; Oxalate; Oxidation; Soil washing; Zero-valent iron