Efficient removal of cadmium and lead ions from water by hydrogels modified with cystine

A hydrogel based on poly(N-isopropylacrylamide) (NIPA) crosslinked with the diacryloyl derivative of cystine (BISS) was synthesized using the free radical polymerization. The NIPA-BISS hydrogel rich in cystine appeared to be a competitive sorbent and has been applied to efficiently remove heavy metal pollutants, mainly cadmium and lead ions, from water. Sorption capacity, kinetics of sorption, swelling behavior and effect of pH on sorption were investigated. Scanning electron microscopy and FTIR analysis were employed to monitor the changes that took place in the NIPA-BISS hydrogels after the adsorption of Cd(II) and Pb(II).