Selective Transport of Bismuth from Heavy Metal Solution by Ionic Liquid-Based Polymer Inclusion Membrane IL-PIM

Abstract

Bismuth is an important critical metal which is under risk of supply. It is mainly found andextracted at trace amounts in copper, lead, tin and gold mining by-product. In this work, we present the resultsof the selective transport of trace bismuth Bi(III) from a solution of heavy metals by an Ionic liquids-basedPolymer Inclusion Membranes (PIM), using the task-specific ionic liquid: trihexyl(tetradecyl) phosphoniumsalicylate (THTDPS), as extractant and ion carrier. The TS-IL was first synthesized by exchanging the inorganicanion of trihexyl(tetradecyl) phosphonium chloride Cyphos IL 101 with the organic anion of sodium salycilate.Important parameters influencing extraction and transport have been examined and optimized. The studied PIMis composed of 50% CTA, and 50% THTDPS without any additional chemical (modifier or plasticizer).The performance and stability of the PIM was carried out in depth. The selective transport of Bi(III) froma solution containing the heavy metals: Pb(II), Cu(II), Cd(III), Ni(II) was carried out. The feed phase iscomposed of trace concentration of the metal ions (10 mg.L-1) in 1M HCl. The optimal receiving phaseconditions were studied and the best composition is EDTA 0.05M at pH 5. The PIM exhibits a good selectivitytowards Bi(III), and the transport rates are reported to be 74.8 ± 9% for Bi(III), against 62.23%, 14.8 ± 9%, 3.15± 3.15%, and 2.5 ± 2.5% for Cd(II), Pb(II), Cu(II), and Ni(II), respectively. The study of the stability shows thatthe PIM can be used up to 5 cycles of extraction-back extraction without significant decrease in the efficiency.