Photocatalytic Removal of Cr(VI) in Water by Collagen-based Biochar/g-C₃N₄/WO₃ Composite

The g-C₃N₄/C/WO₃ photocatalyst was prepared by mixing the graphitic carbon nitride (g-C₃N₄) and C/WO₃ that was pyrolyzed by using the tungsten ions tanned discarded collagen fiber in tanning filed following mineral tanning mechanism. Furthermore, the morphology, structure, and properties of g-C₃N₄/C/WO₃ photocatalyst were characterized by scanning electron microscopy, X-ray diffraction, fluorescence spectroscopy and so on. The results showed that the specific surface area of g-C₃N₄/C/WO₃ reached 244.62 m²/g, which was much higher than that of pure g-C₃N₄ (9.95 m²/g), meanwhile the photocatalytic performance of g-C₃N₄/C/WO₃ was significantly improved. The experiments of Cr(VI) removal showed that the removal rate of Cr(VI) by g-C₃N₄/C/WO₃ was as high as 99.99% under the condition that the amount of catalyst was 0.1 g, the pH of the solution was 2, and the initial concentration of Cr(VI) was 50 mg/L, which was almost not affected by the coexisting substances in water. Additionally, the cycling performance of g-C₃N₄/C/WO₃ was relatively stable after three cycles.