title: Abiotic reductive extraction of arsenic from contaminated soils enhanced by complexation: arsenic extraction by reducing agents and combination of reducing and chelating agents.
abstract: Abiotic reductive extraction of arsenic from contaminated soils was studied with various reducing agents and combinations of reducing and chelating agents in order to remediate arsenic-contaminated soils. Oxalate and ascorbic acid were effective to extract arsenic from soil in which arsenic was associated with amorphous iron oxides, but they were not effective to extract arsenic from soils in which arsenic was bound to crystalline oxides or those in which arsenic was mainly present as a scorodite phase. An X-ray photoelectron spectroscopy study showed that iron oxides present in soils were transformed to Fe(II,III) or Fe(II) oxide forms such as magnetite (Fe3O4, Fe(II)Fe2(III)O4) by reduction with dithionite. Thus, arsenic extraction by dithionite was not effective due to the re-adsorption of arsenic to the newly formed iron oxide phase. Combination of chelating agents with reducing agents greatly improved arsenic extraction from soil samples. About 90% of the total arsenic could be extracted from all soil samples by using a combination of dithionite and EDTA. Chelating agents form strong complexation with iron, which can prevent precipitation of a new iron oxide phase and also enhance iron oxide dissolution via a non-reductive dissolution pathway.
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 Environmental Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju, Jeollabukdo 561-675, Republic of Korea.
authors.forename: Jae-Cheol
authors.initials: JC
authors.lastname: Lee
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: D000327:Adsorption; D001151:Arsenic / Q000737:chemistry*; D001205:Ascorbic Acid / Q000737:chemistry; D002614:Chelating Agents / Q000737:chemistry*; D004227:Dithionite / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry; D010070:Oxalates / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D019163:Reducing Agents / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry*
chemical_list: D002614:Chelating Agents; D005290:Ferric Compounds; D010070:Oxalates; D010087:Oxides; D019163:Reducing Agents; D012987:Soil; D012989:Soil Pollutants; D004227:Dithionite; C000499:ferric oxide; D001151:Arsenic; D001205:Ascorbic Acid
keywords: Arsenic; Chelating agent; Reducing agent; Reductive extraction; Soil