title: [Chemical extraction of arsenic co-precipitated with amorphous Fe (OH)3 and Fe3O4].
abstract: The mobility and bioavailability of As combining with amorphous Fe oxides is vulnerable to the environment. In order to figure out the specific effects of ageing time, Fe/As molar ratio and extractant-to-solid ratio on As extraction procedure, we chose 1 mol x L(-1) hydrochloride acid and 0.2 mol x L(-1) ammonium oxalate/oxalic acid as extractants to extract synthetic Fe (OH)3-As and Fe3O4-As co-precipitates. The results showed that: (1) During the extraction of Fe(OH) 3-As and Fe3O4-As co-precipitates by 1 mol x L(-1) hydrochloride acid, extractant-to-solid ratio should be 50 and 200, respectively; while extracted by 0.2 mol x L(-1) ammonium oxalate/oxalic acid, the molar ratio of C2O4(2-) to Fe in Fe(OH)3 and Fe3O4 solid phases should be 4 and 2.5, (2) The extraction time conducted by hydrochloride acid and ammonium oxalate/oxalic acid should be within 2 hours. (3) The Fe-to-As molar ratio and ageing at room temperature had a little influence on the extraction of Fe(OH)3-As co-precipitation, but significantly influenced on Fe3O4-As co-precipitation. With increase of the Fe/As molar ratio and extension of the ageing time, the Fe3O4-As co-precipitate became more difficult to be dissolved. (4) It was worth noting that, As would be re-adsorpted by the insoluble solid phase during the extraction by hydrochloride acid and ammonium oxalate/oxalic acid. So the inaccurate measurement would emerge during the extraction of As combining with amorphous Fe oxides.
authors.affiliation: Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China. chenyiping020217@163.com
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Chen
authors.forename: Shao-Feng
authors.initials: SF
authors.lastname: Wang
authors.forename: Yong-Feng
authors.initials: YF
authors.lastname: Jia
mesh_terms: D001149:Arsenates / Q000737:chemistry / Q000302:isolation & purification; D001151:Arsenic / Q000737:chemistry / Q000302:isolation & purification*; D011232:Chemical Precipitation; D004785:Environmental Pollutants / Q000737:chemistry / Q000302:isolation & purification*; D005290:Ferric Compounds / Q000737:chemistry*; D006851:Hydrochloric Acid / Q000737:chemistry; D019815:Oxalic Acid / Q000737:chemistry
chemical_list: D001149:Arsenates; D004785:Environmental Pollutants; D005290:Ferric Compounds; C000499:ferric oxide; C021024:ferric hydroxide; D019815:Oxalic Acid; D001151:Arsenic; D006851:Hydrochloric Acid