Sol-gel synthesis of B-TiO2(20%)/HZSM-5 composite photocatalyst for azophloxine degradation

Photocatalyst in the supported form is more meaningful in large scale wastewater treatment than using powder material. HZSM-5 zeolite was used to support boron-doped anatase TiO2 in a sol-gel route in this work. The supported B-TiO2(20%)/HZSM-5 composite photocatalyst has strong activity on azophloxine degradation. The crystallite size of anatase TiO2 slightly increased from 6.1 to 8.4 nm when calcination temperature rose from 350 to 450 degrees C. The bandgap energies were around 3.3 eV for the composites calcined between 350 and 600 degrees C. The adsorption-desorption isotherm of the composites was the type IV isotherm for mesoporous material. The porous structure in the supported B-TiO2 layer was responsible for the variations of both BET surface area and pore volume in the composite. The maximum photocatalytic activity was obtained on the sample calcined at 450 degrees C. After 30 min of irradiation, 61.8% of the initial azophloxine molecules were degraded on the material. The first order reaction rate constant was 0.06168 min(-1). Photocatalytic degradation efficiency was enhanced with increasing B-TiO2 concentration when the B-TiO2 dosage was below 400 mg/L. [GRAPHICS] .