Environmental contextPlatinum complexes are widely used to treat cancer; however, these compounds are also rapidly excreted in the urine of patients and can therefore enter waterways, presenting a toxic hazard to the environment. The biopolymer chitosan was found to be an effective and fast adsorbent for capturing multiple platinum complexes currently applied in medicine. This new approach using biomaterials is proposed to treat such drug residues while at the same time recovering the valuable metal from urine.
AbstractThe majority of platinum used in antineoplastic drugs is rapidly excreted through the urine. These residual platinum compounds are highly toxic, and may eventually reach the aquatic environment if not remediated. Furthermore, platinum is a precious metal that is also relatively scarce, and it is therefore also economically worthwhile to capture and recycle it. We propose that biomass-derived adsorbents would be effective for recovering platinum from diluted streams, including synthetic human urine. Compared with ultrapure water, the salts and small biomolecules present in urine pose additional competition for active binding on the biosorbents’ surface. Chitosan, biochar, wood ash and granular activated carbon were found to effectively adsorb between 0.23 and 0.97mgg−1 inorganic PtIV when a minimal adsorbent dose of 10gL−1 was applied. The fastest adsorption rate was observed using chitosan (k2=728gmg−1min−1), followed by wood ash (k2=49.4gmg−1min−1) and biochar (k2=6.18gmg−1min−1). Substantial differences in platinum recovery were observed among inorganic PtIV, cisplatin, carboplatin and oxaliplatin, which indicates that the adsorbate speciation is highly important for establishing a hydrometallurgical purification technique.