Copper recovery via polyelectrolyte enhanced ultrafiltration followed by dithionite based chemical reduction: Effects of solution pH and polyelectrolyte type

Chemical reduction achieved the complete copper recovery for solution containing PSS. The copper recovery efficiencies were more than 95% for PAA solution with pH values ranging from 3 to 9 at reaction time of one hour. For PEI, the recovery efficiencies ranged from 20 to 96% and were pH dependent. Aggregated and settled readily copper particles were produced by chemical reduction in PSS solution. XRD analysis identified cuprous oxide in all of the samples. Dependent of pH and polyelectrolytes, additional peaks matching those of elemental copper were identified. TGA analysis showed that solids produced from PSS and PAA systems contained no polyelectrolytes while solid collected from PEI system contained 32% of polyelectrolyte.