Pectin/poly(acrylamide-co-acrylamidoglycolic acid) pH sensitive semi-IPN hydrogels: selective removal of Cu2+ and Ni2+, modeling, and kinetic studies

In this study, we have developed pH sensitive potential semi-IPN hydrogels which are composed from pectin, acrylamide, acrylamidoglycolic acid using N,N'-methylene-bis-acrylamide as a cross-linker. The formation and morphology of semi-IPNs were confirmed by FTIR and SEM studies. Swelling and metal ion uptake studies of the semi-IPN hydrogels were performed for Cu2+ and Ni2+ ions. Competitive adsorption studies were also carried out for Cu2+, Co2+, and Ni2+. Further the kinetics data were fitted with pseudo-first and pseudo-second-order kinetic models to investigate the adsorption mechanism. The equilibrium data were interpreted by the Langmuir, Freundlich, and Temkin models. The maximum adsorption capacity of semi-IPN hydrogels calculated from the Langmuir model was found to be 203.7 and 121.7mgg(-1) for Cu2+ and Ni2+ ions, respectively. The adsorption process is described by a pseudo-second-order kinetic model.