Application of Ion Exchangers to Recovery of Metals from Semiconductor Wastes

This paper describes the equilibrium behaviour of a wastewater resembling that produced during semiconductor and printed circuit board manufacture when contacted with a chelating ion exchange resin (Chelex-100; Bio-Rad Laboratories). Distribution coefficients (solid phase metal concentrations/soluble metal concentration) were calculated, and it was determined that the order of affinity was Cu > Pb > Ni > Cr(III). Comparison of the distribution coefficient values obtained in these multicomponent studies with those obtained in prior single component investigutions revealed gross discrepancies. Correction of the current and single component data for soluble phase complexation using an equilibrium computer model reduced the deviations. Computed selectivity coefficients based on culculuted free ionic metal concentrutions showed substantial variation with solid phase composition, indicating that significant solid phase non -idealities existed in this system. Regeneration experiments on spent resin indicated that simple acid regeneration could recover more than 90 percent of the exchanged copper. Based on this study it would uppeur thut treatment of mixed metal wustes generated in printed circuit hoard and electropluting operation by ion exchange is a technically feasible process for removal and recovery of metals, especially copper.