Development of metal separation technique using microcapsules

本项目实现了对Cu（II）、Pb（II）和Ag（I）具有选择性萃取能力的金属萃取微胶囊的制备。主要研究结果如下：1.在w/o乳液体系中，通过缩聚反应，制备了含有水溶性大分子金属配体海藻酸或聚乙烯亚胺的微胶囊。两种微胶囊对各种金属离子均表现出有效的萃取能力，聚乙烯亚胺微胶囊的萃取能力高于其他微胶囊。2.考察了微胶囊对Cu（II）、Co（II）、Ni（II）、Cd（II）、Fe（III）、Pb（II）和Ag（I）的最佳萃取条件。结果表明，Pb（II）以PbCl_4 ~+的形式被萃取<2->，Ag（I）在萃取过程中被还原。3.用荧光显微镜和扫描电子显微镜测定了微胶囊的粒径和膜厚度。XPS表面分析表明微胶囊膜表面存在功能性配体基团，并解释了萃取实验中金属在微胶囊膜上的富集现象。4.微胶囊对微量金属的吸收。在这项研究中制备的微胶囊具有更大的容量比传统的螯合树脂的金属吸收。

This project attained the preparation of metal extractable microcapsules with selective extractability for Cu (II), Pb (II) and Ag (I). The principal results obtained were summarized as follows,1.By polycondensation reactions in w/o emulsion systems, microcapsules containing water-soluble macromolecular metal ligand, alginic acid or polyethylene imine, were prepared. Both microcapsules exhibited effective extractability for various metal ions, higher in polyethylene imine microcapsules than the other.2.Optimal conditions for the uptake of Cu (II), Co (II), Ni (II), Cd (II), Fe (III), Pb (II) and Ag (I) were examined. The results suggested that Pb (II) was extracted as PbCl_4^<2-> and that Ag (I) was reduced during the extraction.3.Size and membrane thickness of the microcapsules were determined by means of a fluorescence microscope and a scanning electron microscope. Surface analysis by XPS revealed the existence of functional ligand groups at the surface of microcapsule membrane and explained the metal accumulation at the membrane which was observed in extraction experiments.4.Metal Uptake from a dilute aqueous solution into a trace amount of microcapsules was attained. The microcapsules prepared in this study had a larger capacity for metal uptake than a conventional chelate resin.