Guan Xiao-Hong, Wang Jianmin, Chusuei Charles C
School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin, PR China.
J Hazard Mater. 2008 Aug 15;156(1-3):178-85. doi: 10.1016/j.jhazmat.2007.12.012. Epub 2007 Dec 14.
Removal of arsenate from water using granular ferric hydroxide (GFH) was investigated under different pH and As(V) loading conditions, using batch equilibrium adsorption, FTIR, and EXAFS methods. The arsenate adsorption envelopes on GFH exhibited broad adsorption maxima when the initial As(V) concentration was less than 500 mg/L at sorbent concentration of 10 g/L. As the initial As(V) concentration increased to 500, 1000 or 2000 mg/L for the same sorbent concentration, distinct adsorption maxima appeared and shifted to lower pH. Acidimetric-alkalimetric titration and arsenic adsorption isotherm data indicated that the surface of GFH is high heterogeneous. FTIR spectra revealed that complexes of two different structures, bidentate and monodentate, were formed upon the adsorption of arsenate on GFH, and bidentate complexes were only observed at pH values greater than 6. The EXAFS analyses confirmed that arsenate form bidentate binuclear complexes with GFH at pH 7.4 as evidenced by an average Fe-As(V) bond distance of 3.32 A.
采用批量平衡吸附、傅里叶变换红外光谱（FTIR）和扩展X射线吸收精细结构（EXAFS）方法，研究了在不同pH值和砷（V）负载条件下，使用氢氧化铁颗粒（GFH）从水中去除砷酸盐的情况。当吸附剂浓度为10 g/L且初始砷（V）浓度小于500 mg/L时，GFH上的砷酸盐吸附包络呈现出较宽的吸附最大值。对于相同的吸附剂浓度，当初始砷（V）浓度增加到500、1000或2000 mg/L时，出现了明显的吸附最大值并向较低的pH值移动。酸碱滴定和砷吸附等温线数据表明，GFH表面具有高度的不均匀性。傅里叶变换红外光谱显示，砷酸盐吸附在GFH上时形成了两种不同结构的配合物，即双齿和单齿配合物，且仅在pH值大于6时观察到双齿配合物。扩展X射线吸收精细结构分析证实，在pH 7.4时，砷酸盐与GFH形成双齿双核配合物，平均铁-砷（V）键距为3.32 Å。
