Optimization of the concentration field in a suspended photocatalytic reactor with the periodically changing solar irradiation

Feasibility of the solar photocatalysis has been validated theoretically and experimentally. Main concerns on the solar photocatalysis in the solutions are: the mass transfer limitation between the photocatalyst and the solution, and the concentration or radiation distribution in the photoreactors. Most researches concentrated their research on one aspect. There is limited research considering variable catalysis concentrations together with the changing solar radiation. However, outdoor solar photocatalysis devices, i.e. for hydrogen production or waste water degradation, would practically face this phenomenon. In the present study, the photon absorption in a suspended photocatalytic reactor was simulated by adopting Monte Carlo method and the six-flux radiation absorption-scattering model. Different photocatalyst concentrations were taken into account. Simulation results indicated that the photon absorption had a close relationship with the concentration distribution of the photocatalysts, and that there is an optimal concentration gradient in the photoreactor leading to the maximum photon absorption. Accordingly, the concentration field is optimized according to the changing solar irradiation. The present work is expected to be of effective value for obtaining the optimal operating parameters for industrial solar photocatalytic applications.