Ion-Imprinted Composite Hydrogels with Excellent Mechanical Strength for Selective and Fast Removal of Cu2+

In the present study, Cu2+-imprinted composite hydrogel (Cu2+-ICH) has been prepared by in situ free-radical polymerization. The investigation of mechanical property indicated that the compression strength of the Cu2+-ICH was significantly enhanced by the introduction of silica nanoparticles. The ability of the Cu2+-ICH to adsorb and remove Cu2+ from aqueous solutions was assessed using batch adsorption technique. The adsorption amount was pH dependent, and the maximum adsorption capacity was observed at pH 5.0. The adsorption process could be well described by the Langmuir isotherm. The adsorption equilibrium was achieved within 20 min, and the kinetics of adsorption followed a pseudo-second-order rate equation. The selectivity coefficient of Cu2+-ICH for Cu2+ was S times greater than that of the nonimprinted composite hydrogels (NICH), indicating that the Cu2+-ICH had strong ability to selectively adsorb Cu2+ from several heavy metal ions present in aqueous solutions. Regeneration studies suggested that metal rebinding capacity of the Cu2+-ICH did not change significantly through repeated applications compared with the first run. This suggests that the Cu2+-ICH is a promising sorbent material for the selective removal of Cu2+ from aqueous solutions.