Simultaneous separation of noble metals osmium and iridium in simulated leaching of spent catalysts using nano-alumina microcolumn

• A simple method for simultaneous separation of Os and Ir was developed.
• Os and Ir can be effectively separated and recovered using nano-Al2O3 microcolumn.
• High recovery efficiencies of Os and Ir were obtained in batch and column system.
• Nano-Al2O3 showed high-stability in recycling use and anti-interference ability.
• The method was satisfactorily employed to recovery Os and Ir from SLSSC samples.

Nano-Al2O3 was employed as the micro-column packing material for simultaneous separation/preconcentration of osmium(Os) and iridium(Ir) species. It was found that both of Os and Ir species could be adsorbed quantitatively on nano-Al2O3 within a pH range of 4.0–8.0, however, only Ir(IV) could be quantitatively retained on the micro-column within a pH range of 8.0–10.0, Os(IV) were passed through the micro-column without the retention. Based on this fact, a new method of micro-column separation/preconcentration was developed for simultaneous separation of Os and Ir species. The extraction recoveries for the mentioned noble metals were more than 95%. Nano-Al2O3 micro-column was reused for four times without obvious significant loss of its adsorption activity for Os and Ir species. In order to validate the developed method, recovery of Os(IV) and Ir(IV) from simulated leaching solution of spent catalysts (SLSSC) was achieved successfully. The negligible uptake of Cu(II), Zn(II), Co(II), Ni(II), Cd(II), Pb(II), and Fe(III) in SLSSC was due to the high selectivity and extractability of nano-Al2O3 for osmium and iridium.

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