A Study On Degradation Effect Of Photocatalysis Oxidation For VOCs From Tannery Wastewater

Heterogeneous photocatalysis oxidation technology is a new technique, with theadvantages of low cost and prompt effect. Compared to the traditional techniques, theprinciple of using heterogeneous photocatalysis in wastewater purification is that,with the catalysis of ultraviolet （UV） lamp for absorbing UV light, the photocatalysisproduces a free electron and hole, then generates a very strong oxidation hydroxylfree radicals, which can efficiently oxidize and dissolution toxic organic or inorganiccompounds to produce harmless compounds, such as CO₂and H₂O. Thephotocatalysis is becoming a more important area in wastewater purification for suchadvantages. Thus studying the principle of photocatalysis and exploring new catalysisis important in environment protection. These studies will bring much more value notonly for economic reason but also for the advancement of human society.In this study we used the tannery wastewater as the main pulltion source fortreatment. In order to reduce the release of toxic gas to atmosphere, we usedsuspension type of catalysis to actively decompose VOCs in the tannery wastewater.At the same time, we discussed how the complex catalysis taked in effect, usingbuilding models. The results showed that different catalytic materials have diffident abilities to decompose the Vocs （WO3> TiO2）. Furthermore, the complex catalysis ismuch better than single catalysis. Nano structure of catalysis influenced theirphotocatalysis oxidation activity.In addition, I also studied the photocatalysis activity under different lamps. It isfounded that when the wavelength of lamp was longer than that of UV light（253.7nm）, the degradation effect of compounds in tannery wastewater was muchbetter than that under sunlight. This suggested us that the UV will be more useful intannery wastewater treatment.In general, the experiment proved that the photocatalysis could yield highefficiency in tannery wastewater purifying. The principle of photocatalysis inwastewater degradation is that the catalysis produces serial free radicals under theaction of ultraviolet. This action has close correlation with the the structure ofcatalysis, and the mechanism is concerned with nucleophilic attack of free electron.