The Study On Mathematical Model Of Photocatalytic Reactor

Photocatalytic Oxidation Technology is a new Advanced Oxidation Technology for water treatment,it just rises in recent 30 years.Through this method it can degrade the organic matter into small molecules just like H₂O and CO₂ by light generated strong oxidizer.This method can be widely used in the water treatment field and it also has a good performance for degrading the refractory organics.Unfortunately there is no report about this technology's successful applications in industrial field.For the reason that the design of photocatalytic oxidation reactor is different from the traditional chemical reactor,it must establish the contact between photochemical behaviors and radiation distributions in the reactor.However,it is hard to complete description the radiation transmission process,because there are many factors effect the radiation's transmission. So far there is no simple and effective model for guiding the reactor's design.A new mathematical model for photocatalytic reactor is established by modifying the two-flux model.We use reactive brilliant red K-2BP as imitation contamination,from the experimental data we find the parameters for the dynamical equation,and then we solve the mathematical model by using Crank-Nicholson difference method and invoking a maltlab program.According to the numerical results we find the radiation intensity distributions and the reactant concentration in the reactor.Then we discuss different concentration of catalyst,light intensity,liquid flow and change the reactor's design parameters that how to effect the radiation intensity distributions and the reactant concentration in the reactor.At last we table some proposals that how to control the corresponding parameters to get the optimal degradation effects.The primary outcomes we acquire as follows:(1) Increase the initial concentration of reactive red K-2BP,the degradation rate increase slowly.When the concentration exceed 80mg.L^-1,the degradation rate start descending,the main reason is the active positions on the suface of catalyzer are taken up by contamination.The increased concentration of the solution make the descending to radiation intensity that also has a effect to the phenomena.(2) Under the different initial concetration conditions,the relationship between ln(c₀/c_t,) and t is firt-degree reaction.When the initial concentration is beyond 100mg.L^-1,the value of k become 10 times smaller.Although increase the intial concentration would result to the descending degradation rate,but relationship between In(c₀/c_t,) and t is still firt-degree reaction.(3) The langmuir-Hinshelwood kinetic model can be used to describe the K-2BP's degradation process in the photocatalytic reactor.The reaction rate constant k＝8.62mg.L^-1.min^-1,the adsorption constant K＝2.53 x 10^-2L.mg^-1.(4) A new mathematical model for photocatalytic reactor is established by modifying the two-flux model,the mass transfer equation and kinetic equation.(5) The excessive or insufficient quantity of catalyzer all will effect the degradation rate;The wavelength has a important effect to degradation rate,the relationship between the higher power and degradation rate is not linearity;To choose appropriate flow rate that should consider the originate fluidization rate to ensure the system entirely fluidization and enough reaction time.(6) From compare the exPerimental data with the simulated data,the results indicate the mathematical model has a good pricision.