Visible-light activation of persulfate by nano-Fe/TiO2 photocatalyst towards efficient degradation of acid orange dye

Titanium oxide (TiO2) semiconducting materials attracted great interest in photocatalytic degradation of organic pollutants in the treatment of textile wastewater in recent days. The present study focuses on a sol-gel method for synthesizing nano-Fe doped TiO2 photocatalyst, and employs the advanced oxidation technique termed photocatalytic activation of persulfate to degrade azo dye. The degradation performance of targeted degradant acid orange dye (AO7) was analyzed regarding the impacts of PDS concentration, solution pH, and catalyst dose. Results showed that under visible light irradiation, the removal rate of AO7 can reach a peak of 98.40 % within 40 min at an optimal initial concentration of 0.05 g center dot L-1, a pH of 5, a PDS concentration of 4 mM, and a catalyst dosage of 0.4 g center dot L-1, accompanied by a reaction rate constant of 0.1152 min- 1. Moreover, the higher photocatalytic activity of nano-Fe/TiO2 in comparison to pure TiO2 is attributed to a higher specific surface area, smaller crystalline size, reduced band gap (2.54 eV), and increased efficiency for the electron-hole generation according to SEM, XRD, FTIR, XPS and DRS characterization measurements. The nano-Fe/TiO2 photocatalytic efficiency persisted robustly after 4 runs and also had a high activity in degrading Tetracycline. The photocatalytic mechanism revealed that the persulfate radical (center dot SO4 -) and the hole (h+) followed by superoxide radicals (center dot O2- ) played a crucial role in providing a better photocatalytic activity under visible light irradiation. The outcomes demonstrate future possibilities of applying nano-Fe/TiO2 photocatalyst in the treatment of organic pollutants wastewater under visible light.