parisa azmoon

and 3 more

A novel double Z-scheme ternary heterostructure photocatalyst of MIL-101(Cr)/Fe3O4-SiO2/nanorod-graphitic carbon nitride (MIL-Cr/F@S/nr-GCN) was fabricated via the hydrothermal method. Physicochemical properties of photocatalysts were measured by XRD, FTIR, FESEM, EDX, TEM, BET, PL, and UV-vis DRS analysis. The adsorption and photodegradation of oilfield-produced water (O-PW) pollutants were investigated by synthesized photocatalysts. The ternary heterostructure composite containing 20 wt% of nr-GCN showed remarkable photocatalytic performance than nr-GCN and MIL-Cr/F@S binary composite. The maximum chemical oxygen demond (COD) removal efficiency of synthetic oilfield-produced water obtained 97.4% under visible-light illumination at optimum conditions (pH 4, illumination time 90 min, photocatalyst dosage 0.6 g/L, and pollutant initial concentration 754 mg/L). Also, total petroleum hydrocarbons (TPHs) were removed 98% at these conditions. The kinetic and isotherm adsorption study revealed that the O-PW adsorption process obeyed the pseudo-second-order kinetic and Freundlich isotherm models. The degradations rate of O-PW by ternary composite is 2.8 times, and 2 times higher than the nr-GCN, and MIL-Cr/F@S, respectively. The high specific surface area (653 m2/g), appropriate bandgap energy (1.6 eV), and the good charge carrier separation based on the double Z-scheme caused the enhancement of photocatalytic activity. The ternary photocatalysts exhibited high reusability after 5 cycles without leaching Cr ions into the treated water. The results confirmed that the new ternary heterostructure is a green and robust photocatalyst in treatment of oilfield-produced water.