Effect of rGO loading on Fe₃O₄: A visible light assisted catalyst material for carbamazepine degradation

Carbamazepine (CBZ), an anticonvulsant drug, is one of the most recalcitrant pharmaceuticals detected in wastewater. For the photocatalytic degradation of CBZ, visible light assisted heterogeneous Fenton-like hybrid composites were synthesized via a co-precipitation method by anchoring magnetite (Fe₃O₄) with reduced graphene oxide (rGO). The rGO loading not only reduced the aggregation of Fe₃O₄ nanoparticles, but also increased the adsorption capacity of the hybrid composites. The mass ratio of rGO in the composites substantially affected CBZ photocatalytic degradation and a 10 wt% rGO loading (rGF10) provided nearly complete CBZ degradation within 3 h. Moreover, the addition of rGO reduced the charge recombination of the bare Fe₃O₄ nanoparticles and provided more accessible reactive sites, enhancing the degradation capacity. The visible light excited Fe₃O₄ nanoparticles yielded reactive species such as hydroxyl radicals (·OH), holes (h⁺), and superoxide radicals (O₂·^-) during the photodegradation process that were evaluated by using specific scavengers during the degradation experiment. The hybrid catalyst was effective under wide pH ranges (from 3 to 9) and showed faster degradation rates in the acidic condition. The composites were magnetically separable, easily regenerated, and exhibited considerably high photocatalytic activity up to five cycles.