Extraction of Cupric Ions with Ionic Liquids Containing Polypyridine‐type Small Molecules or Peripherally Pyridine‐modified Dendrimers

Abstract

The hydrophobic ionic liquid N-butyl-N-methylpyrrolidinium bis((trifluoromethyl)sulfonyl)amide (BMP-TFSA IL), which contains a series of flexible ionophores of polypyridine-type small molecules or two rigid ionophores of peripherally pyridine-modified PAMAM dendrimers, was used to extract cupric ions from aqueous solutions. The polypyridine-type ionophores show good selectivity toward cupric ions at pH 2. The selectivity is affected by the spacing between the two amino groups. However, the pyridine-modified dendrimers showed poor selectivity, although their extraction efficiency still depended on the pH of the aqueous solution. The ionic liquids that contained small molecular ionophores and their dendrimer analogs were reused after acid washing or electrochemical reduction. During acid washing, the nitrogen atoms of the ionophores were protonated to release the cupric ions into the aqueous phase, and the copper atoms were deposited onto the electrode surface during the electrochemical reduction accompanied by the regeneration of the ionophores.

A Review: Adsorption and Removal of Heavy Metals Based on Polyamide-amines Composites

“…In 2003, Rether and Schuster (2003) synthesized novel metal-chelating dendrimers from PAMAMs modified by benzoylthiourea, which can effectively remove heavy metal ions [Co(II), Pb(II), Hg(II), Ni(II), Cu(II), and Zn(II)]. Su et al (2012) prepared a series of PAMAMs dendrimer hydrophobic ionic liquid N-butyl-N-methylpyrrolidinium bis((trifluoromethyl) sulfonyl)-amide modified with polypyridine-type flexible small molecular ion-carriers or two rigid ionophores to extract Cu (II) ions from aqueous solution. However, the problem of poor selectivity of polypyridine-type modified PAMAMs remains to be solved.…”