Intensification reactive recovery of tetravalent platinum from spent catalyst via synergism of TBP/Cyanex 302 system

Synergistic reactive extraction of platinum (IV) from aqueous solution was conducted using an organic phase consisting of tributylphosphate (TBP) and bis (2,4,4-trimethylpentyl monothiophosphinic acid (Cyanex 302) in kerosene. Influence of different type of single extractants, mixtures and their composition towards synergistic effect were investigated. Recovery of platinum (IV) from loaded platinum-organic phase was conducted using an acidic thiourea solution. Results show that the extraction efficiency of platinum using 0.10 M Cyanex 302 and 0.10 M TBP were 10 and 0.5 % in 1 hour, respectively. About 80% of platinum (IV) was extracted using 0.05 M Cyanex 302 + 0.05 M TBP with highest distribution ratio (D = 4.08) and synergist factor (Rf =2.22). Both TBP and Cyanex 302 acted as a base and synergist extractant, respectively. Through synergism system, the concentration of the both extractants (0.10 M) was reduced by 50% (0.05 M). Such findings contribute towards intensification of this reactive extraction since comparing to the single system, the synergistic and productive extraction with minimal use of extractants was obtained via abovementioned mixture system. Meanwhile, almost 98% of platinum (IV) was successfully recovered using 3.0 M thiourea in 3.0 M hydrochloric acid (HCl) in two stages of stripping process.

Automated summary

Synergistic reactive extraction of platinum (IV) was conducted using TBP and Cyanex 302, with the highest extraction efficiency achieved when using a mixture of 0.05 M Cyanex 302 + 0.05 M TBP. Through the synergism system, the concentration of extractants can be reduced by 50% while maintaining a productive extraction process. Additionally, platinum (IV) can be successfully recovered using thiourea in hydrochloric acid.