Ion exchange purification of a silver nitrate electrolyte

Abstract

A novel ion exchange process was studied to remove high concentration of Cu impurity from AgNO3 electrolyte was studied. A suitable ion exchange resin was screened using laboratory scale experiments with a synthetic nitrate electrolyte solution of the following composition: 80.5–90.3 g/L Ag and 37.9–44.3 g/L Cu. Based on simulations with a developed mechanistic ion exchange model, a process scheme was constructed for the best resin, 2-(aminomethyl)pyridine functional chelating CuWRAM. The process was shown to be capable of producing 0.46 BV/h of a purified electrolyte solution containing >70 g/L Ag and <10 g/L Cu. Based on the simulations, roughly 10% of the Ag would be lost to eluate, but because the model overestimates Ag adsorption, the actual percentage is assumed to be lower as based on breakthrough experiments as the model overestimates the Ag adsorption.