水铁矿及其腐殖酸复合体对Sb(Ⅴ)的吸附行为研究

Study on adsorption behavior of Sb(Ⅴ) by ferrihydrite and its humic acid complex

在实验室条件下制备了水铁矿和水铁矿与腐殖酸复合物,通过X射线衍射、傅里叶红外光谱、Zeta电位及比表面积的测定对其基本性质进行了表征,并采用静态批处理吸附试验研究了水铁矿及其腐殖酸复合物对Sb(Ⅴ)的吸附行为特征,探讨了吸附时间、初始pH值、初始浓度、不同干扰离子(PO4^3-、CO3^2-、NO3^-和Cl^-)对水铁矿及其复合物吸附Sb(Ⅴ)的影响.结果表明:腐殖酸与水铁矿结合后未改变水铁矿的晶型结构,但降低了水铁矿的零电点与比表面积.水铁矿及其复合物对Sb(Ⅴ)的吸附过程符合Langmuir和伪二级动力学模型,腐殖酸的加入抑制了水铁矿对Sb(Ⅴ)的吸附.随着pH的上升,水铁矿与复合物的去质子化能力增强,对Sb(Ⅴ)的吸附量减小;溶液中共存离子PO4^3-、CO3^2-对水铁矿及其腐殖酸复合物吸附Sb(Ⅴ)有较强的抑制作用.

The ferrihydrite and its complex with humic acid were synthesized under laboratory conditions. The basic properties of the sample were characterized, including X-ray diffraction, Fourier infrared spectrum, Zeta potential and specific surface area. Adsorption of antimony(Ⅴ) on ferrihydrite and its humic acid complex was studied by batch experiments under static state,,and effects of adsorption time, pH, initial antimony concentration and interfering ions(PO4^3-、CO3^2-、NO3^- and Cl^-) on antimony adsorption were discussed. Results show that the combination of humic acid and ferrihydrite does not change the crystalline structure of ferrihydrite, but reduces the point of zero charge and specific surface area of ferrihydrite. It is shown that the adsorption of antimony on ferrihydrite and its humic acid complex was fitted well with pseudo-second order kinetics and Langmuir isotherm model. It is shown that the presence of humic acid inhibits the adsorption of Sb(Ⅴ) by ferrihydrite. With the increase of pH, the deprotonation ability of ferrihydrite and its humic acid complex is enhanced, and the adsorption amount of Sb(Ⅴ) decreased. The co-existence of PO4^3-、CO3^2- obviously inhibits antimony adsorption on ferrihydrite and its humic acid complex.