Polystyrene-based magnetic hydrogels for elimination of some toxic metal cations from aqueous solutions

Three smart novel polystyrene-based hydrogel nanocomposites were introduced for recovery of some divalent heavy metals (Cu2+ ad Pb2+) from simulated solutions for industrial wastewater remediation. In this regard, magnetic nanoparticles were prepared then fabricated with polystyrene waste and a copolymer of acrylic acid and acrylamide in presence of an initiator/crosslinking system. The chemical amendment process was established by the IR spectroscopy and the prepared hydrogels were characterized by the AFM microscopy and XRD analysis. Moreover, the elimination efficacy of the prepared hydrogels was monitored for Cu2+ and Pb(2+)versus different temperatures and pH values in simulated solution. The data showed a direct relation between the contact time and the amount of the metal removed. Moreover, it was found that the removal efficiency decreases within the region between LCST of polyacrylamide and HCST of polystyrene. It was also proved that maximum metal removal was attained at neutral pH. The maximum removal was achieved by the hydrogel with minimum magnetite content with removal capacity of 128 mg/g of Cu2+ and 122 mg/g of Pb2+ in single removal experiments at optimum test conditions. In double removal experiments, the prepared hydrogels showed obvious selectivity towards Cu2+ ions. The reusability of the investigated hydrogels was examined at three swelling-deswelling cycles.