Thermoresponsive Ion-Imprinted Hydrogels with Interpenetrating Network Structure for Removal of Heavy Metal Ions

Abstract

A novel thermoresponsive Cu(II) ion-imprinted hydrogel [Cu(II)-IIH] with interpenetrating network structure has been prepared to remove Cu(II) ions with high selectivity. The Cu(II)-IIH was prepared by free radical/cationic hybrid photopolymerization of N-isopropylacrylamide (NIPAM) and triethylene glycol divinyl ether (DVE-3) using Cu(II) ion as template. The Cu(II)-IIH was used to remove heavy metal ions from aqueous solution at 20 and 40oC. The Cu(II)-IIH selectively bound the template ion above a lower critical solution temperature (LCST) of poly(N-isopropylacrylamide) (PNIPAM). The memory was fixed by shrinking above the LCST, and was deleted by swelling below the LCST. Selective adsorption study indicated that ion imprinting resulted in stronger affinity of the Cu(II)-IIH toward Cu(II) ions than other competitor metal ions compared with the non-imprinted hydrogel (NIH).