writer：Shengfu He, Fan Zhang*, Shenzhen Cheng, Wei Wang
keywords：P(AANa-co-AM)/GO; hybrid hydrogel; Pb2+; Cd2+; Adsorption
source：期刊
specific source：ACS Sustainable Chemistry & Engineering
Issue time：2016年

 A serials of cross-linked sodium acrylate and acrylamide copolymer /graphene oxide (P(AANa-co-AM)/GO) hydrogels with different mass ratio of AA (acrylic acid) to AM and different content of MBA (N,N-methylenebisacrylamide) were prepared via dispersive polymerization, the prepared hydrogels were well characterized by XRD, FT-IR,TGA, SEM, and BET. Their performances including tensile strength, swelling ratio and removal efficiency for Pb2+ and Cd2+ were also measured. The addition of GO (1.0 wt%) for the copolymer hydrogel improved significantly the 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 the adsorbent for systematic adsorption of Pb2+ and Cd2+ from aqueous solutions. The adsorption capacity and 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+. The adsorption kinetics and adsorption isotherms of Pb2+ and Cd2+ followed pseudo-first order model and the Langmuir isotherm model, respectively. The maximum adsorption capacities of Pb2+ and Cd2+ were calculated to be 452.25 and 196.38 mg/g at 298 K, respectively.The XPS analysis revealed that the adsorption mechanism of Pb2+ and Cd2+ on P(AANa-co-AM)/GO hydrogel was ascribed to the chelation of –COO- with Pb2+

and the ion-exchange of –COO-Na+ with Cd2+, respectively. The results of adsorption-desorption cycle suggested P(AANa-co-AM)/GO hydrogel possessed good reusability, and the fixed-bed column adsorption-desorption operation for simulated Pb2+ wastewater

demonstrated that P(AANa-co-AM)/GO hydrogel can remove effectively heavy metal wastewater and realize easily in-situ regeneration in fixed-bed column, which suggested that P(AANa-co-AM)/GO hydrogel can be considered as a promising adsorbent for removing heavy metal ions from practical wastewater.