Effect of oxidation degree on the synthesis and adsorption property of magnetite/graphene nanocomposites

A facile approach is demonstrated to synthesize a series of magnetite/graphene nanocomposites by solvothermal method, which can be easily collected after removal of pollutants without secondary pollution of graphene powders. Raman and FT-IR analyses show that the reduction of the mixing vapor of ammonia and hydrazine at different reaction periods generates the discrepancy of oxidation degree for reduced graphene oxide (rGO), which can be kept after the solvothermal synthesis of Fe ₃ O ₄ /rGO nanocomposites. Batch adsorption experiments indicate that the nanocomposite with maximum oxidation degree of rGO presents the largest magnetization of 35.4 emu g ^-1 and adsorption capacity of 59.2 mg g ^-1 for Cu ²⁺ , while the one with minimum oxidation degree exhibits the strongest adsorption of 39.0 mg g ^-1 for methylene blue accompanied with appropriate magnetization of 9.0 emu g ^-1 , and only 23% of initial capacity was lost after seven recycling use. The adsorption kinetics of the both composites follows the pseudo-second-order model, suggestive of physical and chemical interactions between the pollutants and adsorbent. The results suggest that the oxidation degree of the rGO substrate can apparently influence both the structure and the adsorbing behavior of Fe ₃ O ₄ /rGO nanocomposites, which allows the control over the adsorbent performance according to the pollutant of interest.