Study On Immobilization Of Nano Semi-Conductor Photocatalyst And Design Of Photocatalytic Reactor

The recycling and immobilization of nano semiconductor photocatalyst and design of photocatalytic reactor are two technical problems needed to be solved in the practical study of nano semiconductor photocatalyst. In this work, two tentative ideas are brought up as to the immobilization of nano titanium dioxide photocatalyst, and then immobilized components are prepared, and on the basis of that, photocatalytic reators are designed and frabricated.According to the tentative idea of immobilizing photocatalyst with coating, nano titanium dioxide photocatalytic coating is prepared with acryl-modified silicone as an adhesive and isocyanate as the cross-linking agent. The coating was prepared under optimized condition when the mass fraction of adhesive was 42%, the mass fraction of cross-linking agent was 7%, and mass fraction of P25 TiO₂ was 5%. Glass plate is used as the subtrate, and the prepared coating is immobilized on it, and thus forming the photocatalytic component. Finally, shallow pond photoreactor is designed and built. In the self-made photoreactor, the immobilized TiO₂ has an excellent photocatalytic performance for penicillin-making wastewater, which was near the suspended nano TiO₂.According to the tentative idea of immobilizing photocatalyst with fine sand, supported nano TiO₂ photocatalyst is synthesized with sol-gel method, with tetrebutyltitanate and ethyl alcohol as the reactants, and 40-80 mesh fine sand as the carrier, and the three-phase internal circulating photoreactor is designed and built, with the structureal parameters and operating optimized. In the experiment setting, penicillin-making wastewater is treated with the prepared supported nano TiO₂ as the photocatalyst. The results show that when the liquid flow rate and the air flow rate reach 300L/h and 40L/h respectively, the mass transfer resistance can be ignored, besides when dosage of the supported photocatalyst is around 8g/L, the reactor can degrade the wastewater effectively, with the degration rate up to 46%.