Synthesis of g-C3N4/biochar materials for photocatalytic degradation of doxycycline in aqueous solution under visible light irradiation

This study used reed biomass and urea as raw materials to produce biochar and g-C3N4 by pyrolysis under N2 atmospheric conditions at 400oC and 520oC, respectively. The g-C3N4/biochar materials were prepared by dispersing different masses of g-C3N4 onto the biochar surface and characterized by XRD, SEM, BET, FT-IR and UV-Vis-DRS methods. The photocatalytic degradation on doxycycline (DC) was investigated from the factors of pH and concentration. The characterization showed that g-C3N4 was well incorporated on the surface of biochar and increased the specific surface area of the material. The presence of biochar narrowed the band gap and increased light absorption at a wider wavelength range of g-C3N4. The composite of g-C3N4/biochar ratio of 2/1 presented the best performance, which is 2.38 times faster than g-C3N4 degrading DC. Kinetic studies showed that DC degradation followed pseudo-first-order kinetics with a determined rate constant kapp = 4,82×10-2 min−1 at a concentration of 5.0 mg/L DC. The study shows that the g-C3N4/biochar material has great potential in the treatment of antibiotic contaminated wastewater.