Evaluation of FeO-MnO@RGO magnetic nanocomposite as an effective persulfate activator and metal adsorbent in aqueous solution.

A reduced graphene oxide (RGO) supported FeO-MnO nanocomposite (FeO-MnO@RGO) was successfully prepared for catalytic degradation of oxytetracycline (20 mg/L) by potassium persulfate (PS) and adsorption removal of mixture of Pb, Cu, and Cd ions (each 0.2 mM) in the synchronous scenario. The removal efficiencies of oxytetracycline, Pb, Cu, and Cd ions were observed as high as 100%, 99.9%, 99.8%, and 99.8%, respectively, under the conditions of [PS] = 4 mM, pH = 7.0, FeO-MnO@RGO dosage = 0.8 g/L, reaction time = 90 min. The ternary composite exhibited higher oxytetracycline degradation/mineralization efficiency, greater metal adsorption capacity (Cd 104.1 mg/g, Pb 206.8 mg/g, Cu 70.2 mg/g), and better PS utilization (62.6%) than its unary and binary counterparts including RGO, FeO, FeO@RGO, and FeO-MnO. More importantly, the ternary composite had good magnetic recoverability and excellent reusability. Notably, Fe, Mn, and RGO could play a synergistic role in the improvement of pollutant removal. Quenching results indicate that surface bounded SO was the major contributor to oxytetracycline decomposition, and the -OH groups on the composite surface shouldered a significant role in PS activation. The results indicate that the magnetic FeO-MnO@RGO nanocomposite has a good potential for removing organic-metal co-contaminants in waterbody.