Yan Dan, Li Hui-Ji, Cai Hou-Qin, Wang Mei, Wang Chun-Chang, Yi Hai-Bo, Min Xiao-Bo
State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, People's Republic of China.
State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, People's Republic of China.
Chemosphere. 2018 Mar;194:117-124. doi: 10.1016/j.chemosphere.2017.11.150. Epub 2017 Dec 1.
The mechanism of As(V) removal from the drinking water and industrial effluents by iron materials remains unclear at the molecular level. In this work, the association of Fe-based materials with As(V) species was explored using density functional theory and ab initio calculations. Solvent separated ion pair structures of [FeHAsO] species may be dominant in an acidic solution of FeAs complex. The association trend of HAsO species by Fe is found to be quite weak in the aqueous solution, which may be attributed to the strong hydration of Fe and [FeHAsO] species. However, the association of HAsO species by colloidal clusters is quite strong, due to the weakened hydration of Fe(III) in colloidal structures. The hydrophobicity of Fe-based materials may be one of the key factors for their As(V) removal efficiency in an aqueous phase. When the number of OH coordinated with Fe(III) increases, the association trend of As(V) by colloidal ferric hydroxides weakens accordingly. This study provides insights into understanding the coprecipitation and adsorption mechanisms of arsenate removal and revealing the high efficiency of arsenate removal by colloidal ferric hydroxides or iron salts under moderate pH conditions.
铁材料从饮用水和工业废水中去除五价砷（As(V)）的机制在分子水平上仍不明确。在这项工作中，利用密度泛函理论和从头算计算探索了铁基材料与As(V)物种的缔合情况。[FeHAsO]物种的溶剂分离离子对结构可能在FeAs络合物的酸性溶液中占主导地位。研究发现，在水溶液中，Fe与HAsO物种的缔合趋势相当弱，这可能归因于Fe和[FeHAsO]物种的强水合作用。然而，由于胶体结构中Fe(III)的水合作用减弱，胶体簇与HAsO物种的缔合很强。铁基材料的疏水性可能是其在水相中去除As(V)效率的关键因素之一。当与Fe(III)配位的OH数量增加时，胶体氢氧化铁对As(V)的缔合趋势相应减弱。这项研究为理解砷酸盐去除的共沉淀和吸附机制以及揭示在中等pH条件下胶体氢氧化铁或铁盐去除砷酸盐的高效率提供了见解。
