One-Step Electrochemical Preparation of Lead Powders and Sulfur Nanoparticles from Solid Lead Sulfide in Deep Eutectic Solvents without SO2 Gas

Abstract

One-step electrochemical preparation of lead powders and sulfur nanoparticles without SO2 gas is investigated for the first time from solid lead sulfide (PbS) in choline chloride-ethylene glycol deep eutectic solvent (ChCl-EG DES) at 353 K. Cyclic voltammetry of the PbS powders on powder cavity microelectrode indicates that solid PbS can be directly reduced to metallic lead at −0.22 V (vs. Ag). Constant voltage electrolysis is carried out from 2.3 V to 2.7 V cell voltage in graphite crucible filled with PbS powders which is used as cathode. Experimental results show that metallic lead and elemental sulfur are obtained instead of SO2 gas at the cathode and anode, respectively. The morphologies of lead powders change from irregular nanoparticles to needle-like or octahedral particles with the increase of applied cell voltage. Amorphous and irregularly globular sulfur nanoparticles with diameters of 30–65 nm are also obtained. These findings promise a green and simple route for clean extraction of metals from their metal sulfide sources in DESs at near room temperature with distinctive merits of no SO2 emissions and good operation environment.