Gradient Corporation, 20, University Road, Cambridge, MA 02138, USA.
Water Res. 2010 Feb;44(3):965-73. doi: 10.1016/j.watres.2009.10.047. Epub 2009 Nov 29.
Single solute As (III) and As (V) sorption on nano-sized amorphous and crystalline TiO(2) was investigated to determine: size and crystallinity effects on arsenic sorption capacities, possible As (III) oxidation, and the nature of surface complexes. Amorphous and crystalline nanoparticles were prepared using sol-gel synthesis techniques. For amorphous TiO(2), solute pH in the range of 4-9 had a profound impact on only As (V) sorption. As (III) and As (V) sorption isotherms indicated that sorption capacities of the different TiO(2) polymorphs were dependent on the sorption site density, surface area (particle size) and crystalline structure. When normalized to surface area, As (III) surface coverage on the TiO(2) surface remained almost constant for particles between 5 and 20 nm. However, As (V) surface coverage increased with the degree of crystallinity. X-ray absorption spectroscopic analysis provided evidence of partial As (III) oxidation on amorphous TiO(2) rather than crystalline TiO(2). The data also indicated that As (III) and As (V) form binuclear bidentate inner-sphere complexes with amorphous TiO(2) at neutral pH.
研究了单溶质三价砷（As(III)）和五价砷（As(V)）在纳米级无定形和结晶 TiO(2)上的吸附，以确定：大小和结晶度对砷吸附容量的影响、可能的 As(III)氧化以及表面络合物的性质。采用溶胶-凝胶合成技术制备了无定形和结晶纳米颗粒。对于无定形 TiO(2)，在 4-9 的范围内，溶液 pH 对仅 As(V)的吸附有深远的影响。As(III)和 As(V)吸附等温线表明，不同 TiO(2)多晶型体的吸附容量取决于吸附位密度、表面积（粒径）和晶体结构。当归一到表面积时，TiO(2)表面上的 As(III)表面覆盖率对于粒径在 5 至 20nm 之间的颗粒几乎保持不变。然而，As(V)表面覆盖率随结晶度的增加而增加。X 射线吸收光谱分析提供了证据表明，在无定形 TiO(2)上发生了部分 As(III)氧化，而不是在结晶 TiO(2)上。数据还表明，在中性 pH 下，As(III)和 As(V)与无定形 TiO(2)形成双核双齿内球络合物。
