Development of metal separation technique using microcapsules

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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.