title: Enhanced reductive extraction of arsenic from contaminated soils by a combination of dithionite and oxalate.
abstract: Iron oxide minerals are the most important sinks of arsenic in arsenic contaminated soils. Therefore, the effective extraction of arsenic bound to the iron oxides is essential to increase the efficiency of arsenic removal from soils. In this study, the reductive extraction of arsenic from contaminated soils was studied with a combination of dithionite and oxalate in order to remediate arsenic-contaminated soils via the reductive dissolution of arsenic associated iron oxides. The addition of oxalate greatly enhanced the reductive arsenic extraction by forming strong complexes with iron, which could prevent the precipitation of a new iron oxide phase and also enhance the iron oxide dissolution via a non-reductive dissolution pathway. Iron in soils can either be extracted as a soluble Fe(C2O4)2(2-) or remain in the soil as a solid Fe(C2O4) precipitation depending on the oxalate to iron molar ratio. Arsenic extraction was hindered by an excess of dithionite, and the optimum dithionite concentration was affected by the arsenic concentrations and the speciations present in the soils. Relatively high arsenic extraction could be obtained by a combination of dithionite and oxalate at a wide range of pH conditions.
authors.affiliation: Department of Bioactive Material Sciences, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju, Jeollabukdo 561-675, Republic of Korea.
authors.forename: Eun Jung
authors.initials: EJ
authors.lastname: Kim
authors.affiliation: Department of Bioactive Material Sciences, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju, Jeollabukdo 561-675, Republic of Korea; Department of Environmental Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju, Jeollabukdo 561-675, Republic of Korea. Electronic address: kbaek@jbnu.ac.kr.
authors.forename: Kitae
authors.initials: K
authors.lastname: Baek
mesh_terms: D001151:Arsenic / Q000737:chemistry*; D004227:Dithionite / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D004787:Environmental Pollution; D005290:Ferric Compounds / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008906:Mining; D010070:Oxalates / Q000737:chemistry*; D056910:Republic of Korea; D012987:Soil; D012989:Soil Pollutants / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D005290:Ferric Compounds; D010070:Oxalates; D012987:Soil; D012989:Soil Pollutants; D004227:Dithionite; C000499:ferric oxide; D001151:Arsenic
keywords: Arsenic; Dithionite; Oxalate; Reductive extraction; Soil