Construction of Z-scheme FeTiO3/g-C3N4 heterojunction system: Characterization and statistical optimization of photocatalytic behavior under visible light irradiation

Construction of low-cost and green photocatalysts is an emerging subject in wastewater treatment processes. In the present study, FeTiO3/g-C3N4 (FTO/CN) photocatalytic system was constructed via ultrasonication followed by thermal mixing method. The synthesized FTO/CN hybrids with different CN ratios were characterized by SEM-EDX, TEM, XRD, XPS, XRF, UV–vis DRS, PL techniques. The photodegradation efficiencies of the hybrid materials were systematically examined towards decolorization of tartrazine dye under visible light irradiation. Using the FTO/CN hybrid catalyst, the photocatalytic efficiency of the pristine FeTiO3 greatly enhanced from 39.8% to 90.5%, which was attributed to appropriate band alignment and heterojunction transfer mechanism to hinder the recombination rate of photo-excited charge carriers. The effects of initial pollutant concentration (10–30 mg/L), catalyst dosage (0.1–0.5 g/L) and peroxymonosulfate (PMS) concentration (1–3 mM), as independent variables on the degradation efficiency were investigated by response surface methodology with Box-Behnken design model. Under optimized conditions (R2 = 0.99, R2adj = 0.98), the highest removal efficiency (100 %) was obtained with 0.5 g/L catalyst, 10 mg/L initial dye concentration and 3 mM PMS. The photodegradation efficiency of the hybrid system was investigated towards other pollutants (Sunset yellow, orange II, tetracycline and ciprofloxacin) and recyclability of the catalyst was also explored. The obtained results demonstrated that the hybridization of FeTiO3 particles with g-C3N4 sheets greatly enhanced the photocatalytic properties of FeTiO3 under different conditions.