Study On The Photocatalytic Degradation Of The Typical Odor Compounds In Raw Water

In this paper, the photocatalytic degradation of the typical odor compounds in raw water which wereβ-cyclocitral,β-Ionone, a-cedrol was studied, and the hypothesis of Langmuir-Hinshelwood (L-H) dymamic model was tested and verified for their degradation. Based on that, several factors were changed to study their effects on the rate constant of the photocatalytic degradation, including the property and concentration of photocatalyst, the initial concentration of the odor compounds, and the power of the light source. As a comparison, titanium dioxide nanotube (TNT) was synthesized, and Fe, W was doped with different quantities to it. Characterization of the synthesized catalysts including X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and BET were performed to understand their properties, and the rate constant of the photocatalytic degradation was measured to investigate their photocatalytic performance. Flavor Profile Analysis (FPA) was done to evaluate the photocatalysts'effects on the removal of the odorants.The results exhibited that the photocatalytic degradation ofβ-cyclocitral,β-Ionone, a-cedrol were in accordance with the first-order model, and their rate constants increased with the concentration of the photocatalyst, the initial concentration of the odor compounds and the power of the light source on the whole. But the efficiency of the light source and the stabilization of the photocatalyst descended when the concentration of the photocatalyst grew above a certain value, and the photocatalyst adsorbed too much intermediate products when the initial concentration of the odor compounds was too high. In that case, the degradation would slow down.The results of the characterization, photocatalytic degradation and FPA showed that W-TNT (3at.%) performed best by comparison, and O.I. of the raw water reduced to an ideal grade after degradation and few new odors appeared. The odor removal effect depended on the composition of the photocatalyst used more, rather than higher BET surface that contributed little.At last, the mechanism of the photocatalytic degradation of P-cyclocitral,β-Ionone, a-cedrol were inferred after the determination of the intermediates. And the determination of the intermediates supported the theory that-OH and other free radicals took a role in the catalytic oxidation of organics.