Semiconductor photocatalytic oxidation of h-acid aqueous solution

The photocatalytic oxidation of H-acid has been performed in aqueous solution by irradiating with a 30 watts low-pressure mercury lamp and using semiconductors TiO2, ZnO, CdS, Fe2O3 as catalysts. The results indicate that TiO2and CdS have higher catalytic efficiency thanZnO and Fe2O3. H-acid can be degraded more than 90% during a period of5 hours irradiation when TiO2 is used as catalyst. The kinetic experiments allow to express the rate of photocatalytic oxidation by Langmuir-Hinshelwood kinetics model where the constants K and k are 12.3 L/mmol and 25.2 x 10−6 mol/h respectively. The reaction time for removal of 90% H-acid can be shortened when 10 mg/L Fe3+ or Ag+ is added to H-acid solution. The effects of amount of catalyst, pH and the initial concentration of H-acid in the solution on the photocatalytic oxidation of H-acid were also investigated.