Task-specific thioglycolate ionic liquids for heavy metal extraction: Synthesis, extraction efficacies and recycling properties

Sonja Platzer; Mega Kar; Raphlin Leyma; Sonia Chib; Alexander Roller; Franz Jirsa; Regina Krachler; Douglas R MacFarlane; Wolfgang Kandioller; Bernhard K Keppler

doi:10.1016/j.jhazmat.2016.10.054

Task-specific thioglycolate ionic liquids for heavy metal extraction: Synthesis, extraction efficacies and recycling properties

J Hazard Mater. 2017 Feb 15;324(Pt B):241-249. doi: 10.1016/j.jhazmat.2016.10.054. Epub 2016 Oct 24.

Affiliations

¹ Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Waehringer Str. 42, 1090 Vienna, Austria.
² School of Chemistry, Monash University, Clayton, Victoria 3800, Australia.
³ Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Waehringer Str. 42, 1090 Vienna, Austria; Department of Zoology, University of Johannesburg, PO Box 524, Auckland Park, 2006 Johannesburg, South Africa.
⁴ Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Waehringer Str. 42, 1090 Vienna, Austria. Electronic address: wolfgang.kandioller@univie.ac.at.

PMID: 27856054
DOI: 10.1016/j.jhazmat.2016.10.054

Abstract

Eight novel task-specific ionic liquids (TSILs) based on the thioglycolate anion designed for heavy metal extraction have been prepared and characterized by ¹H and ¹³C NMR, UV-Vis, infrared, ESI-MS, conductivity, viscosity, density and thermal properties. Evaluation of their time-resolved extraction abilities towards cadmium(II) and copper(II) in aqueous solutions have been investigated where distribution ratios up to 1200 were observed. For elucidation of the IL extraction mode, crystals were grown where Cd(II) was converted with an excess of S-butyl thioglycolate. It was found by X-ray diffraction analysis that cadmium is coordinated by five oxygen and one sulfur donor atoms provided by two thioglycolate molecules and one water molecule. Leaching behavior of the hydrophobic ionic liquids into aqueous systems was studied by TOC (total dissolved organic carbon) measurements. Additionally, the immobilization on polypropylene was elucidated and revealed slower metal extraction rates and similar leaching behavior. Finally, recovery processes for cadmium and copper after extraction were performed and recyclability was successfully proven for both metals.

Keywords: Heavy metal extraction; Immobilization; Reusability; Task-specific ionic liquids; Thioglycolic acid.