Removal of platinum (IV) from hydrochloric acid medium with OMImT: Theoretical and experimental evidences for a neutral complexing mechanism

Abstract As Disperser solvents are commonly toxic and volatile organic solvents in industry, disperser-free strategy enjoys the advantages of environmental benignity and cost control. In this work, 1-octyl-3-methylimidazole-2-thione (OMImT), a neutral sulfur-bearing extractant with low melting point and negligible vapor pressure, was synthesized and first utilized for the removal of Pt(IV) from hydrochloric acid medium by disperser-free precipitation owing to its excellent hydrophobicity and low viscosity. Estimation for the removal performance of Pt(IV) by disperser-free precipitation, in comparison with that by liquid-liquid extraction (LLE) with disperser cyclohexane, was conducted on the effects of the dosage of OMImT and vibration time. Subsequently, variable influence factors on the removal of Pt(IV) (e.g. phase ratio, HCl concentration, H+ concentration and Cl− concentration) were also explored. Afterwards, the removal mechanism of Pt(IV) with OMImT was first proposed and evidenced to be a special neutral complexing mechanism via a combination of quantum-chemical calculations and experimental measurements. At last, kinetic data were analyzed by kinetics fitting methods. In brief, OMImT is a highly effective, environmentally benign and cost efficient candidate for the Pt(IV) removal.