Nano γ-Fe₂O₃/bentonite magnetic composites: Synthesis, characterization and application as adsorbents

Nano γ-Fe₂O₃modified bentonite magnetic composites (γ-Fe₂O₃/Bent) were synthesized via an annealing approach of the ferric oleate and bentonite compounds. The γ-Fe₂O₃nanoparticles with narrow size distribution and an average diameter of 32 nm were equably dispersed on the surface and between layers of the bentonite nanosheets, which mainly owed to the complete mixture of ferric oleate and hydrophobic modified bentonite. The γ-Fe₂O₃/Bent composites exhibited typical ferromagnetic characteristics with the saturation magnetization of 22.31 emu/g and coercivity of 209 Oe. Adsorption performance measurement indicated that the γ-Fe₂O₃/Bent composites are a kind of excellent adsorbent with fast adsorption rate, high adsorption capacity, 99.99% removal rate and easily magnetic separation process for the removal of cationic dye methylene blue (MB). Adsorption kinetics and isotherms were studied to describe the adsorption process, and the electrostatic adsorption mechanism was confirmed by zeta potential measurement.