Development of Process for Silver Recovery from Photographic Wastes.

摘要

The purpose of this work was development of a silver recovery process based upon Donnan dialysis, a continuous ion exchange system in which separation of ionic species is achieved by transport across an ion exchange membrane. The role of intrinsic membrane parameters on the transport of ions in Donnan dialysis appears more complex than originally postulated. The available data indicate that there are optimal values for ion exchange capacity and membrane hydrophilicity. If ion exchange capcity or hydrophilicity are too low, no ion transport occurs. Increasing ion exchange capacity appears to increase the ion transport rates, but the attendant increase in membrane hydrophilicity leads to a loss of ion permselectivity. It thus appears that a balance in ion exchange capacity and hydrophilicity must be achieved to provide an acceptable membrane. While these conclusions should be considered tentative, it appears that this is the best explanation of the results obtained in this study based upon the available data. It is recommended that further membrane study be conducted prior to any work toward developing a prototype Donnan dialysis system for silver recovery.