Research On Organic Polluts Removal Using Quick-separated Photocatalytic Reactor

The organic contaminates have become the focal point of worldwide attention. Kinds of watertreatment technique appeared against organic contaminate. The technology of photocatalytic oxidation is a kind of green technique against environmental pollution, especially to a trace of organic contaminates in drinking water, being characteristic of removing and mineralizing pollution completely and bring no second pollution, so it enjoys the reputation of "Sunday punch". Besides, it can degrade harmful organic contaminates of large molecule with high concentration into minor numerator organic compounds which is easy to degrade and innocent to people. Therefor it can be the pretreatment of high concentration wastewater which is difficult to degrade.The problem of separate photocatalyst from reaction liquid in suspended photocatalytic oxidation reactor was the obstacle for research man. A quick-separated photocatalytic oxidation reactor integrated reaction with separatation was designed, which successfully separated photocatalyst from reaction liquid. And the effect of removing organic contaminates and its influencing factors were studie. The results of our research show in the below:1 Photocatalysts were successfully separated after reaction in quick-separated photocatalytic oxidation reactor, the the water effluent was clear, and the water turbidity was less than 0.4 Ntu.2 Quick-separated photocatalytic oxidation reactor can remove the organic contaminates effectively. When adding 1g/L photocatalyst of type-I ,the removal of 3hCOD_Mn,3hTOC and 3hUV₂₅₄ in the running water were 17.3%, 29.9% and 67.4% respectively. Under the same reaction conditions, the removal rate of 3h phenol and 3hTOC were 93.8% and 47.3% when degrading the phenol solution in which the initial concentration of phenol solution was 4.34mg/L. When adding 0.1g/L photocatalyst of type- I ,the removal of Atrazine, BPA, Trichloromethane and Hexachlorobenzene with 220μg/L around were respectively 94.9%,98.7%,84.4% and 74.7% in 1 hour. 3 The kinetic equation of photocatalytic degradation of Phenol, Atrazine, BPA, Trichloromethane and Hexachlorobenzene were obtained by Langmuir-Hinshelwood.model. The experimental results show that the photocatalytic reaction is a first order reaction.4 Enough reaction time was an important facter for removing was an important factor in photocatalytic oxidation process.The longer time prolonged; the more organic compounds were removed. However, the rate of mineralization was less than the rate of oxidization.5 Different photocatalyst have different effect on photocatilytic effect. In our study, type-I and type-V TiO₂ performed best in water treatment.6 Proper quatity of photocatalysts was needed in the process. The optinal amount of photocatalyst was 1 g/L around when running water was disposed by UV/TiO₂.7 The irradiance affects the process of oxidizing organic contaminates, the organic degradation rate and degradation efficiency were decreasing with ultraviolet light number reducing, and the arrangement of lights also affects the process.8 The more the initial concentration of orgnic compounds became, the lower the degradation rate is getting, and the worse dislodging efficiency is becoming. The microcontant of organic contaminates and metal ion and negative ion impact the process of disposing main organic pollutants, disadvantage against the advantage.9 Reaction liquid was mixed well by forcing recycled water, and photocatalysts were distributing uniformly. When circulation rate of flow was changed in a range, photocatalytic effect was invariant.10 Adding H₂O₂ or O₃ can improve the rate and efficiency of photocatalytic oxidation greatly. The coordinate effect was beter when simultaneously adding H₂O₂ and O₃ into UV/TiO₂ than adding either H₂O₂ or O₃ in it. System of UV/ H₂O₂/O₃/TiO₂ can shorten the time of reaction to achieve the same effect.In our study, According to the value of reaction rate k, the order of different systems from high to low were:UV/H₂O₂/O₃/TiO₂ >UV/O₃/TiO₂ >UV/H₂O₂/TiO₂ > UV/O₃ > UV/H₂O₂ > UV/TiO₂.