零价铁(ZVI)去除水中的As(Ⅲ)

Removal of arsenite from aqueous environment by zero-valent iron(ZVI)

采用市售还原铁粉（零价铁,ZVI）及其与石英砂的复合物为吸附剂,对水中As（Ⅲ）的吸附分别做了分批试验和连续性试验。分批试验结果表明,ZVI吸附水中As（Ⅲ）的去除效果受p H主导,其最佳p H范围4-9,ZVI主要通过其表面吸附及其腐蚀产物对As（Ⅲ）的吸附共沉淀作用达到对As（Ⅲ）的去除,同时,在ZVI腐蚀的过程中还伴有在ZVI表面As（Ⅲ）的氧化、还原作用,As（Ⅲ）的氧化受ZVI腐蚀过程的影响,其氧化过程主要发生在Fe2＋氧化为Fe^3＋的阶段;连续性试验利用ZVI与石英砂复合物对模拟含砷废水进行吸附研究,从吸附柱进水至吸附饱和共20 d时间,经计算,ZVI对As（Ⅲ）的吸附容量为89.90 mg·g^-1,ZVI腐蚀产物在石英砂表面的晶态类型对As（Ⅲ）的吸附容量有影响,无定形态的ZVI腐蚀产物对As（Ⅲ）的吸附容量最大,质量分数和原子分数分别可达到6.73%和2.15%。

The batch and column experiments on removal of As（Ⅲ） from aqueous environment by zero-valent iron（ZVI） and quartz sand mixed with ZVI were studied. The batch test results showed that removal efficiency of As（Ⅲ） by ZVI was dependent on p H value and the optimum range of p H was 4—9. As（Ⅲ） was mainly removed though adsorption and co-precipitation by the surface of ZVI and its corrosion products. Meanwhile, simultaneous oxidation and reduction of As（Ⅲ） on the surface of ZVI occurred during the corrosion process of ZVI. As（Ⅲ） was oxidized in oxidation of Fe^2＋ to Fe^3＋. Quartz sand mixed with ZVI was used for the adsorption of As（Ⅲ） from simulated arsenic-containing wastewater in the column experiment. After 20 d of continuous adsorption of As（Ⅲ）, the column was saturated. The calculated adsorption capacity of As（Ⅲ） by ZVI was 89.90 mg·g^-1 and the adsorption capacity of As（Ⅲ） was affected by the crystalline types of ZVI corrosion products on the surface of quartz sand. In this study, amorphous corrosion products of ZVI had the largest adsorption capacity, and mass fraction and atom fraction reached 6.73 and 2.15 respectively.