Molecular Insights into Ternary Surface Complexation of Arsenite and Cadmium on TiO2
Molecular Insights into Ternary Surface Complexation of Arsenite and Cadmium on TiO2
复制标题
亚砷酸盐和镉在 TiO2 上三元表面络合的分子见解。
DOI：
10.1021/es5062903
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发表时间：
2015-05-19
影响因子：
11.4
通讯作者：
Jing, Chuanyong
中科院分区：
文献类型：
--
作者：
Hu, Shan;Yan, Li;Jing, Chuanyong
从分子水平上的砷[As（III）]和镉（Cd）共吸附在二氧化钛的机制的见解，可以进一步了解他们在工业废水中的协同去除。我们的研究动机是探索中性电荷的As（III）和阳离子Cd（2+）的纳米TiO 2使用多种互补技术的界面相互作用。吸附边、吸附电位和表面络合模型的结果表明，As（III）和Cd（2+）的共存增强了它们在TiO 2上的协同吸附，从而导致形成三元表面络合物。这种三元表面复合物，反过来，抑制金属释放到水相中，因此，促进了重金属的固定化。我们的原位流动池衰减全反射傅里叶变换红外（ATR-FTIR）光谱和扩展X射线吸收精细结构（EXAFS）光谱的证据表明，无论接触的顺序，As（III）优先吸附在二氧化钛，而不是镉。与我们的光谱分析一致，量子化学计算也表明，Cd-As（III）-TiO 2三元表面络合物应该形成与吸附的As（III）作为桥接分子。在高As（III）浓度下，Cd-As（III）-TiO 2复合物的形成负责Cd的去除。同时去除机制将进一步加深我们对工业废水中多种污染物去除的理解。
Insights from molecular-level mechanisms of arsenite [As(III)] and cadmium (Cd) co-adsorption on TiO2 can further our understanding of their synergistic removal in industrial wastewaters. The motivation for our study is to explore the interfacial interactions of neutrally charged As(III) and cationic Cd(2+) on nanocrystalline TiO2 using multiple complementary techniques. The results of adsorption edge, ζ potential, and surface complexation modeling suggest that coexistence of As(III) and Cd(2+) enhanced their synergistic adsorption on TiO2 and, consequently, resulted in the formation of a ternary surface complex. This ternary surface complex, in turn, inhibited the metal release into the aqueous phase and, therefore, facilitated the immobilization of the heavy metals. Our in situ flow-cell attentuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy evidence showed that, regardless of the order of contact, As(III) was preferentially adsorbed on TiO2 rather than Cd. In agreement with our spectroscopic analysis, quantum chemistry calculations also illustrated that the Cd-As(III)-TiO2 ternary surface complex should be formed with the adsorbed As(III) as the bridging molecule. At high As(III) concentrations, the formation of the Cd-As(III)-TiO2 complex is responsible for the Cd removal. The simultaneous removal mechanisms will further our understanding of the removal of multiple pollutants in industrial wastewaters.