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Kinetic and Thermodynamic Requirements To Extend Solvent Compatibility in Thermal-Assisted Extraction of Inert Platinum Group Metals

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journal contribution
posted on 09.05.2019, 00:00 by Zhiwei Zheng, Tsuyoshi Arai, Koichiro Takao
The extraction behavior of inert platinum group metals (PGMs) like Ru­(III) and Rh­(III) has been investigated in a HNO3(aq)/1-octanol system with a pyridinediamide. As a result, low efficiency of Ru­(III) extraction arose from its slow kinetics at 298 K, while the situation was not improved very much even at 356 K. Addition of a hydrophobic anion like Tf2N increased Ru­(III) extraction up to 95% within 3 h at 356 K, where a synergistic effect would be present. Extraction of a more inert PGM like Rh­(III) was also enhanced up to 90% within 2 h at 356 K in the presence of Tf2N. We have successfully demonstrated the rapid and efficient extraction of inert PGMs from HNO3(aq) to 1-octanol, which is one of the ordinary organic solvents.