CONTINUOUS MEMBRANE DIALYSIS USING ION-EXCHANGE RESIN SUSPENSION FOR EXTRACTING METAL-IONS

A continuous membrane dialysis process using ion-exchange resin suspension has been developed for extracting metals from industrial waste streams. The basic idea is to use a chelating ion-exchange resin in conjunction with a semipermeable membrane. The membrane is capable of retaining the resin and its metal complex while allowing the free metal ion to permeate freely. The process consists of a chelating unit and a stripping unit. In the chelating unit, the resin reacts with certain metal ions and forms a metal complex. In the stripping unit, metal ions are released and the resin is regenerated at a lower pH. The resin suspension is continuously circulated between the chelating and stripping units. Experimental studies have been conducted on the removal of copper ion. The results show that the extraction of metals can be significantly enhanced in comparison with a nonchelating system. In addition to experimental studies, a mathematical model for the process has been proposed and verified on the basis of system identification of the overall physicochemical parameters by fitting the experimental data. The basic process has also been optimized by using the validated model to explore the optimal (minimum operating cost with a specified feed stream and output) process structure and operating conditions.