Photocatalytic degradation of rhodamine B and real textile wastewater using Fe-doped TiO2 anchored on reduced graphene oxide (Fe-TiO2/rGO): Characterization and feasibility, mechanism and pathway studies

In this work, a simple sol-gel method was used to fabricate a ternary nanocomposite of Fe-doped TiO2 decorated on reduced graphene oxide (Fe-doped TiO2/rGO). XRD, Raman shift, FT-IR, BET, DRS, EIS, TEM, FESEM, EDX and EDS techniques were applied for characterization of the structural, optical, and surface morphological properties of the synthesized catalysts. The DRS results of the photocatalysts showed a narrowing band gap by the introduction of Fe ions to the titania framework. The photocatalytic performance of the prepared samples was determined through the decontamination of rhodamine B under solar illumination. The optimum content of iron and graphene oxide and the effect of operational factors including pH, catalyst dosage and the initial concentration of rhodamine B were studied. The findings revealed that a 0.6 g Fe-doped TiO2/ rGO nanocomposite containing 3% Fe and 5% rGO, with an initial pH of 6 and rhodamine B concentration of 20 mg/L could achieve a removal of 91% after 120 min under solar illumination. TOC analyses were conducted to explore the rhodamine B mineralization rate; the data showed complete mineralization after 300 min. The effect of coexisting ions was examined and the results indicated that the degradation efficiency was significantly decreased by the addition of chloride and sulfate anions, although it slightly decreased in the presence of nitrate and phosphate anions. Furthermore, the addition of H2O2 as an enhancer was investigated and the data demonstrated that the addition of 8 mM H2O2 enhanced the photocatalytic efficacy to complete degradation. Finally, in the treatment of real textile wastewater, the concentrations of TOC and COD decreased from 930 mg/L and 1550 mg/L to 310 mg/L and 634 mg/L, respectively, after 390 min under similar operational conditions.