Graphene oxide-wrapped magnetite nanoclusters: A recyclable functional hybrid for fast and highly efficient removal of organic dyes from wastewater

Abstract

We report the facile and cost-effective fabrication of a novel functional hybrid composed of graphene oxide (GO)-wrapped magnetite (Fe3O4) nanoclusters (Fe3O4@GO) by electrostatically driven co-assembly. In comparison with previously reported Fe3O4-GO composites that were prepared through one-pot, in situ deposition of smaller-sized Fe3O4 nanoparticles, the Fe3O4@GO hybrid composite reported in the present study are obtained by weak electrostatic interaction between negatively charged GO nanosheets and positively charged Fe3O4 nanoclusters (size ∼500 nm). The as-prepared Fe3O4@GO hybrid has a core-shell structure where thin and flexible GO shells efficiently infold the Fe3O4 nanocluster core. The adsorptive characteristics of Fe3O4@GO hybrid was evaluated using two model cationic dyes; methylene blue (MB) and rhodamine B (RhB) and one model anionic dye; methyl orange (MO). The adsorption of dyes onto Fe3O4@GO hybrid composite was investigated as a function of solution pH, adsorbent dosage, ionic strength, contact time and temperature. The adsorption kinetics, isotherms, thermodynamics, stability, and reusability of the adsorbent were also studied in detail. The results showed that the adsorption kinetics and the equilibrium adsorptions are well-fitted with pseudo-second order kinetic model and Langmuir isotherm model, respectively. The maximum adsorption capacities for MB, RhB and MO are 131.10, 34.50 and 39.95 mg/g respectively at 303 K. The Fe3O4@GO adsorbent exhibited rapid magnetic separation, easy regeneration, excellent stability, and good sustainability in removal efficiency even after continued recycling. The results demonstrated that Fe3O4@GO composite possesses great potential as an efficient and recyclable adsorbent for the removal of both cationic and anionic dye pollutants in environmental remediation.