Fabrication and characterization of magnetic graphene oxide-g-poly(acrylamide)/gelatin hydrogel nanocomposites for effective adsorption of copper ions from aqueous solutions

Abstract

In this work, a magnetic nanocomposite adsorbent was synthesized by crosslinking graft copolymerization of gelatin and acrylamide onto graphene oxide nanosheets in the presence of Fe3O4 nanoparticles. The structure of nanocomposites was characterized by using FTIR, SEM, TEM, XRD, VSM and point of zero charge (pHpzc). The prepared nanocomposites were employed as bioadsorbents for adsorption of copper ions. The effects of adsorption parameters under different conditions were studied in detail through batch experiments. The maximum ion adsorption capacity of 259 g. g−1 was achieved under the optimum conditions that found to be: pH=8.0, copper concentration=80 mg L-1, adsorbent dosage=0.5 mg mg. L−1, contact time=2 hours, and temperature=60 °C. The kinetics and isotherms of adsorption fitted well at various ion concentrations (40, 80 and 160 mg L−1) using second-order and Langmuir models with the R2=0.9991 and 0.9928, respectively. Moreover, the thermodynamic parameters shown that the adsorption process was spontaneous and endothermic. In addition, the adsorbents depicted excellent regeneration ability after six adsorption-desorption cycles and maintained 89 % of its initial adsorption capacity. In conclusion, the obtained results confirmed that the prepared environmentally friendly nanocomposites with high adsorption capacities could be effective adsorbents for the elimination of different ions from wastewaters.