液膜提取回收土壤淋洗液中镉的研究

Study on Extraction and Recovery of Cadmium from Soil Leachate by Liquid Membrane

针对土壤淋洗液中重金属传统萃取及液膜提取方法效率低的问题,提出组合液膜来提高提取率。该研究采用2己基乙基膦酸单2己基乙基脂(P507)为络合剂的组合液膜提取技术对土壤淋洗液中Cd进行提取。通过考察水相Cd浓度、p H值、络合剂浓度以及接收相组成对Cd提取率的影响。研究结果表明,络合剂与Cd形成络合物在液膜系统中传输,最佳提取条件为:p H值5.0、络合剂浓度5.5%~7.0%、接收相酸浓度为4.0 mol/L、接收相络合剂与接收相体积比30%、水相Cd浓度越低提取率越高。Cd起始浓度为5.0×10^(-3)mol/L时,最佳提取条件下提取率可达92%。

Aiming at tackling the drawback of low extraction efficiency of the traditional heavy metal extraction and liquid film extraction methods concerning soil leached solution, the paper introduced a new combination liquid membrane, which related to the extraction of cadmium（Cd） in soil leachate by composite liquid membrane with 2 hexyl ethyl phosphonate（P507） as a complexing agent. Factors affecting Cd extraction rate were investigated, which included Cd concentration of aqueous phase, p H value of aqueous phase, concentration of complexing agent and the receiving phase composition. The results showed that there existed a sort of transmission regarding the complexing agent and the complex formed with Cd in the liquid membrane system, and the optimum extraction conditions were p H 5.0, concentrations of complexing agent ranging5.5%-7%, concentration of the receiving phase 4.0 mol/L and volume ratio of the complexing agent of receiving phase and receiving phase 30%. It was shown that the lower the concentration of water phase Cd, the higher the extraction rate. Under the optimized conditions, as the initial concentration of aqueous phase was 5.0×10^（-3）mol/L, the extraction rate could reach 92%.