Si-N doped eucalyptus biochar supported TiO2-ZnO (Si-N@EBC/3TiZn) as novel solar light responsive photocatalyst for enhanced degradation of cationic dye in aqueous solution

Abstract

A novel Si-N@EBC/3TiZn composite was developed, analyzed and utilized as a photocatalyst for methylene blue (MB) degradation. The Si-N@EBC/3TiZn at various compositions of Si-N@EBC was investigated and exhibited excellent photoactivity for degradation reaction when the Si-N@EBC composition in the photocatalyst was 30%. Textural analysis showed that 30%Si–N@EBC/3TiZn was a mesoporous material with 80.3 m²/g specific surface area and 19.3 nm pore diameter, while optical analysis showed a remarkable reduction in the band gap of the sample, making it a solar light responsive photocatalyst. The percent MB removal from the photodegradation process was 98.61 $\pm$ 0.21% at optimal initial MB concentration of 24.7 mg/L, pH of 9.84, 30%Si–N@EBC/3TiZn dosage of 1.16 g/L and irradiation period of 51.7 min. The pseudo-first-order L-H model provided a good fit to the MB photocatalytic degradation data with high $R^2$ values. 30%Si–N@EBC/3TiZn was recycled eight times, with 90.78% degradation occurring at the 8th run.