覆铁石英砂对As的固化机理及影响因素

摘要

A batch of experimental research was conducted to analyze the curing mechanism and influencing factors of arsenic(As)from aqueous solutions by iron-oxide coated sand(IOCS)in this paper.The results showed that:the removal efficiency of IOCS on As increased with the rise of Fe concentration on the surface of IOCS,adsorption and solid-liquid distribution coefficients increased with the increase of reaction time.The pseudo-second-order model can better describe the adsorption behavior of As on the surface of the IOCS.The isothermal adsorption test results showed that the fitting effects of Freundlich model were better and the index 1/n decreased with the increasing with the Fe concentration on the surface of IOCS, which indicated that IOCS treated with high concentration of iron salt had stronger constraint for arsenic.In addition, different concentration of IOCS on the adsorption capacity of As(Ⅲ)and As(Ⅴ)increased with the rise of reaction temperature and, while the temperature had a more significant effect on As(Ⅲ)than on As(Ⅴ).The IOCS treated with different iron salt under different pH values had significantly better capacity of adsorption removal of As(Ⅲ), As(Ⅴ)than the untreated sandy media,but both showed the tendency that the adsorption capacity decreased with the increase of pH.%开展了覆铁石英砂(iron-oxide coated sand,IOCS)对水体中不同价态As的固化机理和影响因素的实验研究.结果表明:IOCS对As的吸附去除效率随IOCS表面Fe浓度的升高而增大,吸附量和固液分配系数均随反应时间的增加而增加,准二级反应模型能更好地描述As在IOCS表面的吸附行为.等温吸附实验结果表明:Freundlich的拟合效果较好,指数1/n随着IOCS表面铁浓度的增大而减小,说明经高浓度铁盐处理过的IOCS对于As具有更强的约束能力.此外,不同浓度的IOCS对As(Ⅲ)、As(Ⅴ)的吸附容量均随着反应温度的升高而升高,但温度对As(Ⅲ)的吸附效果的影响相对于As(Ⅴ)更显著.经各浓度铁盐处理过后的IOCS在不同pH值条件下吸附去除As(Ⅲ)、As(Ⅴ)的效果明显好于未经处理的砂质介质,但都呈现吸附量随pH的升高而下降的变化趋势.