Surface Modification of Graphene Oxide with Crosslinked Polymethacrylamide via RAFT Polymerization Strategy: Effective Removal of Heavy Metals from Aqueous Solutions

One of the efficient methods for enhancement of the heavy metal adsorption of nano graphene oxide (GO) is the surface modification through functional polymer. In this study, cross-linked polymethacrylamide (CPMAM) as hydrogel network was synthesized via reversible addition-fragmentation chain transfer (RAFT) technique to graft on the surface of GO activated phenylalanine (GO-Ph). The proposed mechanism for the grafting and chemically crosslinking reactions was proved with various techniques. The modified GO was employed as an excellent adsorbent for the removing of Cd(II) ions from aqueous solutions. The results indicated that ion adsorption basically relies on adsorbing time, solution pH, temperature, and initial Cd(II) concentration. In the optimized condition adsorption capacity was calculated to be 41.14 mg/g. Moreover, the adsorption kinetics and isotherm analysis demonstrated that the adsorption model was fitted with the pseudo-second-order and Freundlich isotherm models, respectively. The thermodynamic study showed that the ion adsorption process was endothermic and spontaneous. Based on the obtained results, the surface-modified GO with CPMAM has the potential to be used in sensitive environment that needs to completely remove Cd(II) ions.