Ion-Selective Imprinted Beads for Aluminum Removal from Aqueous Solutions

The aim of this study is to prepare ion-imprinted polymers that can be used for the selective removal of aluminum ions [Al3+] from aqueous solutions. N-Methacryloyl-l-glutamic acid (MAGA) was chosen as the complexing monomer. In the first step, Al3+ was complexed with MAGA and Al3+-imprinted poly(hydroxyethyl methacrylate-N-methacryloyl-l-glutamic acid) (MIP) beads were synthesized by suspension polymerization. After that, the template ions (i.e., Al3+) were removed using 0.1 M EDTA solution. The specific surface area of the MIP beads was found to be 55.6 m2/g with a size range of 63−140 μm in diameter, and the swelling ratio was 102%. According to the elemental analysis results, the MIP beads contained 640 μmol of MAGA/g of polymer. The maximum adsorption capacity was 122.9 μmol of Al3+/g of beads. The applicability of two kinetic models including pseudo-first-order and pseudo-second-order models was estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium capacity, and correlation coefficients. Results suggest that chemisorption processes could be the rate-limiting step in the adsorption process. The relative selectivity coefficients of MIP beads for Al3+/Ni2+, Al3+/Cu2+, and Al3+/Fe3+ were respectively 1427, 14.8, and 6.2 times greater than that of the nonimprinted matrix. The MIP beads could be used many times without significantly decreasing in their adsorption capacities.