A novel sequential pretreatment coupled with statistically optimized bioleaching for highly effective biorecovery of platinum group metals from spent catalyst waste

The biorecovery of platinum group metals (PGM) from spent catalyst waste is gaining widespread interest as an alternative to conventional recovery processes. A challenging aspect of the biorecovery of PGM from spent automotive catalyst (SAC) is the low biomobilization of PGM due to the complex nature of SAC. This work discusses statistical optimization of the bioleaching parameters using a central composite design for the biorecovery of PGM from SAC. A novel approach is presented where PGM from sequentially pretreated SAC is optimally recovered using heat oxidation, sonication, and reduction prior to bioleaching. An engineered strain of Chromobacterium violaceum was able to leach Pt (76 %), Pd (81 %), and Rh (100 %) from SAC at a pulp density of 0.5 % w/v following three days of spent medium leaching. Under the same conditions, pretreatment of SAC using formic before leaching enhanced the leaching efficiency to Pt (91 %), Pd (95 %), and Rh (100 %) following two days of spent medium leaching. Overall, this study demonstrates the effectiveness of sequential pretreatment before bioleaching and statistical optimization of bioleaching for enhanced biorecovery of PGM.

Automated summary

This study demonstrates the effectiveness of sequential pretreatment and bioleaching for enhanced biorecovery of platinum group metals (PGM) from spent automotive catalyst (SAC). The optimization of pretreatment and bioleaching parameters significantly improves the recovery efficiency of PGM.