Eco-friendly and facile electrochemical synthesis of sub-micrometer lead powders in deep eutectic solvents using galena as a raw material

Abstract

The sub-micrometer lead powders were electrodeposited on a mild steel (MS) substrate in PbS-containing (10–50 mM) choline chloride–urea deep eutectic solvent (ChCl–urea DES) at 353 K and 2.5 V. The electrochemical behaviors of the Pb(II)/Pb on MS and glass carbon electrodes were determined by cyclic voltammetry and chronoamperometry measurement. It indicates that the reduction of Pb(II) is a quasi-reversible process. The increase in PbS concentration effectively promotes the EPb(II)/Pb shift in positive direction which can facilitate the reduction of Pb(II). The initial nucleation stage of metallic lead on MS electrode is a three-dimensional instantaneous nucleation for diffusion control and the diffusion coefficient of Pb(II) at 353 K is about 2.40 × 10−7 cm2/s. The three-dimensional sub-micrometer lead particles are agglomerated together and composed of many overlapped lead flakes about 150–200 nm. Moreover, the XRD results reveal that metallic lead can be deposited with a face-centered-cubic structure and the strongest peak intensity is (111) plane. This finding provides a theoretical guidance for the one-step preparation of sub-micrometer lead powders using galena concentrate as raw material by an eco-friendly and facile electrochemical approach in close neutral electrolyte, which can efficiently shorten the production flow and realize the integration of metallurgy and material processes.