| In this paper, photocatalytic oxidation process for water purification was studied both in theory and practical application. Several aspects were included: studies of the physical and chemical characteristics of TiO2 and its recycle, kinetic studies of the decomposition of organic compounds over TiO2 photocatalyst, optimal conditions of a photocatalytic system, explorations of a new photocatalytic reactor, and several wastewater treatments using photocatalytic oxidation process, etc..For the first time, the adsorptive amounts of organic compounds on TiO2 in UV-irradiation process and the adsorption expression between TiO2 and residual organic compounds were obtained by a modified menstruation. Took phenol as an example, the adsorption expression was q=(1.1274C0 -0.4965)C. It was proved that the specific adsorption of compounds on TiO2 during the irradiation period was different from the one during the dark period. The prime reason for deactivation of TiOi in process was particle aggregation. Ultrasonic dispersion as an on-site regeneration way for photocatalyst was put forward. The results showed that photoactivity of TiO2 could be changeless after being used whether 20 times repeatedly or 260h continuously.Each influencing factor of the reaction rate was investigated, and the quantitative relations between reaction rate and each parameter were obtained. It was discovered that not all the decomposition rate of organic compounds would decrease with increasing initial concentration. TiOi optimum would change under different organic compound contents. Deficiencies in L-H kinetic model were pointed out and a corrected model was brought forward, the results showed that the latter could describe reaction process better with maximal error less than 8%.The effects of active carbon, ultrasonic and electric field on the slurry phocatalytic system were explored and the results showed that efficiency of combined systems was higher than a single slurry system. The decomposition rate of organic compounds in each combined system was 20% more than that in a single system. Furthermore, correlative mechanisms were analyzed and discussed.PAC and PFS could be used as two coagulating agents for separating catalyst from a sluiry system and the separating ratio would be more than 90%. But the separated catalyst is 30% less than the unused one in photocatalytic activity. Contrast to coagulation, microfiltration could be a better choice. After microfiltration, not only catalyst could be separated completely, but also its photocatalytic activity could be kept.Using ultrofiltration technique to separate photocatalyst from a slurry system was put forward and Photocatalytic UF Membrane Reactor (PUFMR) as a new photocatalytic system was explored. Diluted domestic wastewater was used as influent with COD and TKN concentration of 38.7-67.4 and 4.3-11.9mg/L respectively. The results showed that in the effluent, when FIRT varied from 2h to 8h, COD concentration was around 10mg/L, while TKN and bacteria could not be detected. Based on hydrodynamics, the mathematic models ofPUFMR in two fluid statuses are deduced. The results proved that CFSTR model could predict the results better.Ceramic membrane with photocatalytic activity and photocatalytic lamp had been prepared. The experiment was done using lignin solution and tap water respectively. The results showed that when lignin concentration was 2g/L, flux under illumination was 20% more than the one under no illumination; while when the lignin concentration increased to 5g/L, flux under the two states was almost the same. It was concluded that flux increase under illumination depended on the amount of photon, which could arrive at membrane surface. After being treated with photocatalytic lamp, the removal of volatile phenol, CHCls ,CCl4, bacteria,DOC, residual chlorine and Cr6+ in tap water had a satisfying ending respectively.Photocatalytic oxidation process could be used to treat TNT wastewater and bathing wastewater. In this process, TNT and other compounds could be mineral...
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