EDTA插层水滑石的合成及其对Cd^(2+)的去除性能研究

Synthesis of EDTA intercalated hydrotalcite and application in removal of Cd^(2+)

利用EDTA对重金属离子的螯合作用,将其作为有机阴离子插入到镁铝水滑石的层间,采用共沉淀法制备了复合层状材料EDTA.Mg-Al LDH。通过正交实验确定了NaOH投加量为理论计算值的1.2倍时,合成物的层间阴离子以EDTA4-形式稳定存在。EDTA.Mg-Al LDH处理56 mg/LCd2+溶液的最佳处理条件为:水滑石质量浓度5.0 g/L,反应时间60 min,去除率可达98.20%。并与以无机阴离子Cl-作为插入离子制备的Cl.Mg-Al LDH对56 mg/L的Cd2+溶液的去除率进行了比较,由于层间阴离子EDTA4-对重金属强烈的螯合能力,EDTA.Mg-Al LDH对水中Cd2+的去除效率大大高于Cl.Mg-Al LDH。

The layered composite materials,EDTA· Mg-Al LDH, are prepared with coupling Mg-A1 layered double hydroxide with EDTA anion by co-precipitation. EDTA. Mg-Al LDH can adsorb heavy metal ions. The orthogonal test indicates that the interlayer anion of the compound is stable as EDTA4- when the ratio of the actual amount of NaOH in the EDTA solution to the stoichiometric quantity is 1.2 times as much. The optimal removal effect of Cd2 ＋ with an initial concentration of 56 mg/L by EDTA- Mg-A1 LDH is obtained when the hydrotalcite concentration is 5.0 g/L, and the reaction time is 60 min, the removal efficiency can reach 98.20%. The capacity of Cl· Mg-Al LDH, in which the interlayer anion is Cl- , is also examined. The results show that the removal efficiency of Cd2＋ by EDTA-Mg-Al LDH is significantly higher than Cl-Mg-Al LDH because of the strong chelation of EDTA4-.