Abstract: The kinetic process in a tubular continuous-flow photo-reactor equiped with titanium dioxide immobilized on glass fiber-net has been studied by using methyl orange as a model reactant.The process has been described carefully,and modeled by using dynamic partial differential equation.Since the solution of the equation was complicated,the numerical solution has been undertaken by using a fourth-order Runge-Kutta scheme.The results show that the mathematical simulated values are consistent with the experimental data.Under the condition of different treated reactant amount the actual reaction rate constant k is approximately identical,but the apparent reaction rate constant kapp decreases with increasing treatment of reactant amount.The initial concentration has a great influence upon the rate constant.Below 15 μmol•L－1 of the initial concentration the rate constant tends to be a constant.In the range of 15～150 μmol•L－1,the influence of the initial concentration on the reaction rate constant can be expressed as:lnk=－0.48lnc0＋1.42.The dependence of reaction rate constant on UV irradiation intensity is k∝I 0.5.The pH of initial solution is an important factor in the photocatalysis reaction.

Key words: Immobilized bed, Photocatalysis, Kinetics, Mathematical simulation