Aserials of cross-linked sodium acrylate and acrylamide copolymer /graphene oxide (P(AANa-co-AM)/GO) hydrogelswith different mass ratio of AA (acrylic acid) to AM and differentcontent of MBA (N,N-methylenebisacrylamide) were prepared via dispersivepolymerization, the prepared hydrogels were well characterized by XRD, FT-IR,TGA, SEM, and BET. Their performances including tensile strength, swellingratio and removal efficiency for Pb2+ and Cd2+ were alsomeasured. The addition of GO (1.0 wt%) for the copolymer hydrogel improved significantlythe tensile strength and removal efficiency of Pb2+ and Cd2+.The P(AANa-co-AM)/GO hydrogel with AA/AM=1 and 0.8 wt% of MBA has the highest removal efficiency for Pb2+and Cd2+ and a suitable swelling ratio, which was selected as theadsorbent for systematic adsorption of Pb2+ and Cd2+ fromaqueous solutions. The adsorption capacityand removal efficiency of Pb2+and Cd2+ were highly dependent on pH, initial heavy metal ion concentrations and adsorbent dosage and the presence of 0.01~0.05 M Mg2+or Ca2+ has obvious effect on the adsorption of Cd2+. Theadsorption kinetics and adsorption isotherms ofPb2+ and Cd2+ followed pseudo-first order model and theLangmuir isotherm model, respectively. Themaximum adsorption capacities of Pb2+ and Cd2+ werecalculated to be 452.25 and 196.38 mg/g at 298 K, respectively.The XPS analysis revealed that the adsorption mechanism of Pb2+ andCd2+ on P(AANa-co-AM)/GO hydrogel wasascribed to the chelation of –COO- with Pb2+
and the ion-exchange of –COO-Na+ with Cd2+,respectively. The results of adsorption-desorption cyclesuggested P(AANa-co-AM)/GO hydrogel possessed good reusability, and the fixed-bedcolumn adsorption-desorption operation for simulated Pb2+ wastewater
demonstrated that P(AANa-co-AM)/GO hydrogel can removeeffectively heavy metal wastewater and realize easily in-situ regenerationin fixed-bed column, which suggested that P(AANa-co-AM)/GO hydrogel can beconsidered as a promising adsorbent for removing heavy metal ions frompractical wastewater.
