【摘要】 通过室内试验,研究了铝代水铁矿对As（Ⅴ）和Cd（Ⅱ）的协同作用过程及机制.结果表明,溶液体系p H值和重金属加入顺序明显影响铝代水铁矿对砷和镉的协同吸附与共沉淀.在近中性砷镉共存体系下吸附72h（p H为6. 0～6. 5）,含20%铝的铝代水铁矿（AF20）对砷和镉的吸附容量达到了60. 9 mg·g^-1和17. 1 mg·g^-1,去除率分别为96. 0%和73. 0%,砷和镉协同吸附到AF20颗粒内部孔隙,AF20对砷和镉的协同吸附效应明显;在砷溶液中加入镉体系下吸附72 h（p H为6. 1～6. 5）,AF20对砷和镉的吸附容量分别为58. 1 mg·g^-1和12. 4 mg·g^-1,去除率分别为96. 0%和48. 3%,砷的吸附限制了镉的固定;在镉溶液中加入砷体系下吸附72 h（p H为9. 5～9. 8）,AF20对砷和镉固定量分别为20. 9 mg·g^-1和24. 4 mg·g^-1,去除率分别为38. 8%和98. 9%,AF20对砷和镉的共沉淀效应明显,生成的砷镉难溶物通过堵塞孔道使镉呈稀疏条带状分布,同时阻碍砷的进一步吸附.上述结果表明,铝代水铁矿可协同吸附、共沉淀污染环境介质中的砷和镉.更多还原

【Abstract】 The synergistic process and mechanism of aluminum（ Al）-substituted ferrihydrites on arsenic [As（ Ⅴ） ] and cadmium[Cd（ Ⅱ） ]were studied under laboratory conditions. The results showed that synergistic adsorption and coprecipitation of As and Cd by Al-substituted ferrihydrites was clearly affected by both the p H of solution and the order in which heavy metals were added. The solution in which As co-existed with Cd for 72 hours,at a p H of 6. 0 to 6. 5,the As and Cd adsorption capacity of Al-substituted ferrihydrites containing 20% Al（ AF20） reached 60. 9 mg·g^-1 and 17. 1 mg·g^-1,respectively. The removal rates of As and Cd were96. 0% and 73. 0%,respectively. Arsenic and Cd were synergistically adsorbed into the internal pores of AF20 particles,and the synergistic adsorption effect of AF20 on As and Cd was clear. Adding Cd to the solution containing As,for 72 hours,and with a p H of6. 1 to 6. 5,the As and Cd adsorption capacity of AF20 was 58. 1 mg·g^-1 and 12. 4 mg·g^-1,respectively. The removal rates of As and Cd were 96. 0% and 48. 3%,respectively. Adsorption of As limited the fixation of Cd by AF20. When adding As to the solution containing Cd,for 72 hours,with a p H of 9. 5 to 9. 8,fixed amounts of As and Cd on AF20 were 20. 9 mg·g^-1 and 24. 4 mg·g^-1,respectively. The removal rates of As and Cd were 38. 8% and 98. 9%,respectively. The coprecipitation of As and Cd by AF20 was clear. The resulting insoluble As and Cd compounds distributed the Cd distribution in a sparse strip and impeded the further adsorption of As. The results show that Al-substituted ferrihydrites can synergistically adsorb and coprecipitate As and Cd in contaminated environmental media.更多还原