Journal of Chemical and Engineering Data, Vol.55, No.2, 605-608, 2010
Removal of Metal Ions from Aqueous Solutions by Extraction with Ionic Liquids
This work analyzed the extraction of Zn(2+), Cd(2+), and Fe(3+) from aqueous hydrochloride solutions using ionic liquids in the absence of chelating agents. For this purpose, ionic liquids based on 1-(n-alkyl)-3-methylimidazolium and tetraalkylammonium cations and several anions (hexafluorophosphate, bis[(trifluoromethyl)sulfonyl]imide, tetrafluoroborate, and chloride) were tested. It was found that the ionic liquid methyltrioctylammonium, chloride, [MTOA(+)][Cl(-)], allowed almost complete removal (extraction percentage > 94) of Zn(2+), Cd(2+), and Fe(3+) from the aqueous Solutions. Furthermore, efficient selective separation of Zn(2+)/Fe(3+) and Cd(2+)/Fe(3+) was achieved using 1-methyl-3-octylimidazolium tetrafluoroborate, [omim(+)][BF(4)(-)], since high extraction percentages were reached for Zn(2+) and Cd(2+) (extraction percentage > 90) while this parameter was very low for Fe(3+). These results indicate that the use of ionic liquids as an alternative to traditional extraction agents in liquid/liquid extraction of heavy metal ions is very promising.