[Preparation of a novel modified hydrogel and study of its adsorption performance]

A novel copolymer hydrogel poly(Hydroxyethyl methacrylate/N-Vinylformamide) [p (HEA/NVF)] was prepared by 60Co-gamma induced copolymerization, using low-temperature radiation technique. Triethylenetetramine(TETA) was applied to modify the prepared hydrogel into an ammoniated hydrogel poly (Hydroxyethyl methacrylate/N-Vinylformamide) -TETA [p (H/V) -T]. The two hydrogels prepared were characterized by using FTIR spectrometry and the p (HEA/NVF) was scanned by SEM. Moreover, the p (H/V) -T hydrogels were analyzed by XPS before and after adsorption. The adsorption capacities of Pb2+, Cd2+ on p (HEA/NVF) and p (H/V)-T were investigated. And the effects of pH, time and initial metal ion concentration on the adsorption of Pb2+, Cd2+ by p (H/V)-T were examined in batch experiments. SEM photos showed that p (HEA/NVF) hydrogel is a macroporous polymer material. Compared to the p (HEA/NVF) hydrogel, the adsorption capacities of Pb2+, Cd2+ on p(H/V)-T increased by 700% and 600%, respectively. The adsorption behaviors for Pb2+ and Cd2+ confirmed that the adsorption on p(H/V)-T followed the pseudo-second-order rate equation and was fitted to both Langmuir and Freundlich adsorption model (R2 > 0.95). Besides, the adsorption capacities of p (H/V)-T increased with increasing pH values. The FTIR spectra verified that p (HEA/NVF) was indeed a copolymer of HEA and NVF monomers, and the multi-amine groups have been successfully grafted to the surface of the copolymer hydrogel. The XPS analysis concluded that the mechanism of Pb2+ and Cd2+ by p (HEA/MALA) could be the chelation between -NH2 and metal ions.