Biosorptive recovery of platinum from platinum group metal refining wastewaters by immobilised Saccharomyces cerevisiae

摘要

The process of platinum group metal (PGM) refining can be up to 99.99% efficient at best, andnalthough it may seem small, the amount of valuable metal lost to waste streams is appreciablenenough to warrant recovery. The method currently used to remove entrained metal ions fromnrefinery wastewaters, chemical precipitation, is not effective for selective recovery of PGMs. Thenyeast Saccharomyces cerevisiae has been found capable of sorbing numerous precious and basenmetals, and is a cheap and abundant source of biomass. In this investigation, S. cerevisiae wasnimmobilised using polyethyleneimine and glutaraldehyde to produce a suitable sorbent, capable ofnhigh platinum uptake (150–170 mg/g) at low pH (o2). The sorption mechanism was found to be anchemical reaction, which made effective desorption impossible. When applied to PGM refinerynwastewater, two key wastewater characteristics limited the success of the sorption process; highninorganic ion content and complex speciation of the platinum ions. The results proved the conceptnprinciple of platinum recovery by immobilised yeast biosorption and indicated that a more detailednunderstanding of the platinum speciation within the wastewater is required before biosorption cannbe applied. Overall, the sorption of platinum by the S. cerevisiae sorbent was demonstrated to benhighly effective in principle, but the complexity of the wastewater requires that pretreatmentnsteps be taken before the successful application of this process to industrial wastewater.