Selective separation of Pt(IV) and Ru(III) from the simulated leach liquor of spent electrocatalyst in fuel cells using ionic liquid

초록

Recycling of Platinum (Pt) from the spent electrocatalyst in fuel cells is recently an important alternative to develop a sustainable metallurgy. Although it is an effective process, the separation of Pt from other metals was not intentionally investigated due to the simple compositions of the leach liquor. Therefore, the selective extraction of Pt(IV) and Ru(III) from the impurities Fe (III), Ni(II), and Co(II) in a simulated leaching solution from the electrocatalyst by using Aliquat-336 was studied. The effect on Pt(IV) extraction were investigated by varying other metal and extractant concentrations, and the significant co-extraction of Fe(III) and Ru(III) with Pt(IV) were observed. Fe(III) was completely removed using D2EHPA 0.5 M to prevent the co-extraction. Pt(IV) and Ru(III) can be selectively extracted by two-stage extraction using Aliquat-336 0.5 g/L, and respectively stripped using solution of HCl 1.0 M/ thiourea 0.003 M and HNO<inf>3</inf> 3.0 M. The remaining Ru(III) in the raffinate was separated from Ni(II) and Co(II) by using Aliquat-336 7.0 g/L and stripped by HNO<inf>3</inf> solution. A multi-stage of extraction and stripping process was proposed to completely separate Pt(IV) and Ru(III) from Fe (III), Ni(II), and Co(II), which was advantageous for further purification to their final products with high purities. © 2025 The Korean Society of Industrial and Engineering Chemistry

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