Extraction of Pt(IV), Pt(II), and Pd(II) from Acidic Chloride Media Using Imidazolium-Based Task-Specific Polymeric Ionic Liquid

Abstract

As an excellent separation material to recover platinum group metals (PGMs), imidazolium-based taskspecific polymeric ionic liquid (CP-AMIN) was successfully synthesized and characterized by SEM and FT-IR. The effects of temperature, pH, reaction time, CP-AMIN amount, and concentration of chloride ion were discussed during the process of extraction of Pt(IV), Pt(II), and Pd(II) from acidic chloride media. It shows high extraction efficiency under various conditions, suggesting CP-AMIN has strong adaptability of environment. CP-AMIN also presents excellent selectivity for PGMs in the solutions with coexisting metal ions (Ni 2+ , Mn 2+ , Cu 2+ , Cd 2+ , Co 2+ , and Cr 3+ ), and it indicates the CP-AMIN process efficient task specificity. Notably, the acidic thiourea can desorb PGMs from CP-AMIN almost completely. After seven cycles of adsorption−desorption experiments, the extraction efficiencies still maintain above 85%. This suggests that CP-AMIN also exhibits excellent recyclability. Meanwhile, due to its being easy to handle, safe, and environmentally friendly, the task-specific polymeric ionic liquid promises great potential to recover PGMs from aqueous phase.

A Comparison of Cobalt and Platinum Extraction in Hydrophobic and Hydrophilic Ionic Liquids: Implication for Proton Exchange Membrane Fuel Cell Recycling

“…In the case of SX using [C 14 pyr]­[NTf 2 ], Pt­(IV) is selectively extracted to the IL phase, leaving Co­(II) in the aqueous solution. Pt­(IV) can be subsequently recovered from the IL phase by stripping using an acidified thiourea or thiosulfate solution, , or through its reductive precipitation by hydrazine addition as was previously detailed for IL-based SX.…”

“…The 44,45 or through its reductive precipitation by hydrazine addition 46 as was previously detailed for IL-based SX.…”

“…generally using a stripping step in order to remove the metal ions extracted towards the IL. [44][45][46][47][48] The main recycling concern raised in this work is therefore related to the reusability of the AcABS. Only one instance of such a study for AcABS was reported very recently by our group.…”

Liquid‐ and Solid‐based Separations Employing Ionic Liquids for the Recovery of Platinum Group Metals Typically Encountered in Catalytic Converters: A Review

“…Unfortunately, the authors have not addressed possible leakage of the IL from the polystyrene beads. [215] The authors of the present review recently presented an efficient scheme for the separation of Pt and Pd from Rh and accompanying elements leached from a spent car catalyst with the aid of a phosphonium-based polymerized IL covalently bound on silica surface. Initial experiments on PGM model solutions indicated that parameters such as dilution level, acidity of solution, and IL loading on silica have no effect on the retention of Pt and Pd on the sorbent material, which is quantitative.…”

“…The recyclability potential of the CP‐AMIN was demonstrated with seven absorption‐desorption cycles in which no decline in its sorption capacity was observed. Unfortunately, the authors have not addressed possible leakage of the IL from the polystyrene beads [215] …”