Superabsorbent polymer hydrogels with good thermal and mechanical properties for removal of selected heavy metal ions

This article reports an efficient removal of selected heavy metal ions using a low-cost superabsorbent polymer hydrogel (SPH) composed of acrylic acid and acrylamide in different compositions which were prepared by single step free radical polymerization technique using ammonium persulphate and N, N-methylene bis-acrylamide as an initiator and cross-linker respectively. The morphological, thermal and mechanical properties were assessed for superabsorbent polymer hydrogels. The effect of pH and monomer content on the swelling behaviour of SPH was studied in detail and a maximum swelling capacity of 1841% was found for composition having maximum acrylic acid (AA) content. All the samples were highly effective in the removal of Cd2+, Ni2+, Cu2+ and Co2+ from aqueous medium at pH range of 2-10 following pseudo second order kinetics and Freundlisch adsorption model. Also, the removal capacity was greater at pH 7 and materials showed high selectivity towards Co2+ and Cu2+ in competitive removal process. The high removal ability >75% for each metal ion, make these materials as an efficient, easily obtainable, and environmental friendly product. (C) 2018 Elsevier Ltd. All rights reserved.