Recovery of Platinum Group Metals from Acidic Solutions Using Dithio and Benzimidazolylthio Functionalized Resins

Adsorbents derived from Merrifield’s resin and a reaction with three functionalizing ligands namely 1,2-ethanedithiol (M-EDT), 1,2-benzenedithiol (M-BDT), and 2-benzimidazolylmethylthio acetic acid (M-BITAA), respectively, were synthesized for the recovery and separation of PGMs from simulated solutions. M-EDT, M-BDT and M-BITAA resins were characterized by FTIR, UV-Vis, TGA, CHNS and SEM techniques which confirmed significant structural modifications in these resins. Batch adsorption study revealed that M-BITAA exhibited the highest capacity for Pd(II) with about 26 mg.g-1 while M-EDT and M-BDT resins were both below 10 mg.g-1. The adsorbents obeyed the Langmuir isotherm in 0.8 M HCl solution. Batch adsorption further showed, in a competitive study, that M-BITAA was not selective for Pd(II) but an attractive sorbent for other PGMs such as Pt(IV) which may be advantageous for solutions containing these PGMs.