研究了吸附材料石英砂负载β-FeOOH(ACS)对Cr(Ⅵ)的吸附机理.结果表明,Cr(Ⅵ)在ACS表面的吸附率随ACS表面Zeta电位的降低而显著降低,说明Cr(Ⅵ)的吸附以静电作用为主.石英砂负载β-FeOOH后表面Zeta电位由负变正,说明β-FeOOH在石英砂表面的负载改变了石英砂表面的电荷性质,也表明ACS能对Cr(Ⅵ)产生静电吸附.ACS吸附除Cr(Ⅵ)的能量色散X射线光谱(EDS)和X射线光电子能谱(XPS)测定结果表明,ACS吸附Cr(Ⅵ)的过程发生了一定的离子交换作用,且吸附反应伴随着部分氧化还原反应的进行,氧提供电子,铁、铬接受电子,氧、铁分别起Lewis碱和Lewis酸的作用.
Adsorption mechanism of Cr(Ⅵ) over β-FeOOH-coated sand (ACS) was investigated in this study. The Cr(Ⅵ) adsorption on ACS decreased dramatically with decreasing ACS surface zeta potential, which indicated that the main mechanism of Cr(Ⅵ) adsorption on ACS was electrostatic interaction. With β-FeOOH coating, zeta potential of quartz sand became positive from original negative state, and this suggested that the coating of β- FeOOH could alter the surface charge properties of quartz sand, leading to change of electrostatic adsorption capability. In addition, analyses of energy dispersive X-ray spectrum (EDS) and X-ray photoelectron spectroscopy (XPS) indicated that, in the process of Cr( Ⅵ ) adsorption over ACS, certain ion exchange process and partial oxidation-reduction reactions occurred. In these reactions, 0 served as the electron donor, whereas Fe and Cr were electron acceptors. 0 and Fe functioned as Lewis alkali and Lewis acid, respectively.