Recovery of Pd(II) from Hydrochloric Acid Medium by Solvent Extraction-Direct Electrodeposition Using
Min Shao1, Shunling Li1, Ci Jin1
1Key Laboratory of Medicinal Chemistry for Natural Resource (Yunnan University), Ministry Education, School of Chemical Science and Technology, Yunnan University, Kunming, Yunnan Province 650091, China.
Abstract:
Mixed [C8bet]Br/[C4mim][NTf2] ionic liquids were used as a new extraction system to extract Pd(II) from multimetal-ion solutions. The separation factors K Pd/M (M: Cu, Fe, Ni, Zn, Co) are greater than 103. Thiourea was found to be an effective stripping agent. After three cycles, the recovery efficiency was higher than 91.0%. Direct electrodeposition of palladium from the mixed ionic liquid phase was also studied. The Pd(II) complex in [C8bet]Br/[C4mim][NTf2] system was studied by cyclic voltammetry at 348 K. The results indicate the existence of three types of Pd(II) complex in the [C8bet]Br/[C4mim][NTf2] system, leading to three reductive waves. The reduction of Pd(II) to Pd(0) in this system is irreversible. A uniform black coating was obtained by constant-potential deposition at -1.7 V on a nickel foil, confirmed to be palladium metal by energy-dispersive spectrometry, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy analyses. After three cycles of continuous extraction-electrodeposition, over 90.0% of palladium was recovered.
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