Preparation of Pectin-Acrylamide-(Vinyl phosphonic acid) hydrogel and its selective adsorption of metal ions

Selective metal adsorption is a prominent and novel field in adsorption science where functional hydrogels are playing vital roles. The current study is mainly focused on the synthesis of Pectin-Acrylamide-Vinyl phosphonic acid hydrogels (Pectin-AAm-VPA) and the selective adsorption of metal ions from the solution of multielement. The hydrogels were prepared by applying gamma radiation of different doses ranging from 5 to 50 kGy where 20 kGy was optimized based on the gel content and the equilibrium swelling analysis. The functional groups of the hydrogel were identified by FTIR spectroscopic analysis. Thermal properties-glass transition and melting temperature of the gel were investigated by DSC thermogram. It was an amazing finding that the hydrogels show selective adsorption toward Al, Fe, Ga, In, Mo, and Bi metal ions from the solution containing 27 metal ions. The surface of the gels before and after metal adsorption was inspected using SEM supported by EDS and confirmed the selective adsorption. Metal ions were desorbed successfully in 5% nitric acid. Finally, it can be stated that the Pectin-AAm-VPA hydrogels can effectively be used for selective adsorption of Al, Fe, Ga, In, Mo, and Bi metal ions from the multielement solutions.