title: Fate of Arsenate adsorbed on Nano-TiO2 in the presence of sulfate reducing bacteria.
abstract: Arsenic removal using nanomaterials has attracted increasing attention worldwide, whereas the potential release of As from spent nanomaterials to groundwater in reducing environments is presently underappreciated. This research investigated the fate of As(V) adsorbed on nano-TiO2 in the presence of sulfate reducing bacteria (SRB) Desulfovibrio vulgaris strains DP4 and ATCC 7757. The incubation results demonstrated that As(V) was desorbed from nano TiO2, and subsequently reduced to As(III) in aqueous solution. The release of adsorbed As(V) was two to three times higher in biotic samples than that in abiotic controls. Reduction of As(V) to As(III) in biotic samples was coupled with the conversion of sulfate to sulfide, while no As(III) was observed in abiotic controls. STXM results provided the direct evidence of appreciable As(III) and As(V) on TiO2. XANES analysis indicated that As(V) was the predominant species for three As loads of 150, 300, and 5700 mg/g, whereas 15-28% As precipitated as orpiment for a high As load of 5700 mg/g. In spite of orpiment formation, As mobilized in higher amounts in the SRB presence than in abiotic controls, highlighting the key role of SRB in the fate of As in the presence of nanomaterials.
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Luo
authors.forename: Haixia
authors.initials: H
authors.lastname: Tian
authors.forename: Zhi
authors.initials: Z
authors.lastname: Guo
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Zhuang
authors.forename: Chuanyong
authors.initials: C
authors.lastname: Jing
mesh_terms: D000327:Adsorption; D001152:Arsenicals / Q000737:chemistry / Q000378:metabolism*; D016969:Desulfovibrio vulgaris / Q000378:metabolism*; D053768:Metal Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D013431:Sulfates / Q000378:metabolism; D013440:Sulfides / Q000378:metabolism; D014025:Titanium / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism*; D018508:Water Purification
chemical_list: D001152:Arsenicals; D013431:Sulfates; D013440:Sulfides; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D014025:Titanium