Coupled model based on radiation transfer and reaction kinetics of gas–liquid–solid photocatalytic mini-fluidized bed

Abstract

Gas–liquid–solid mini-fluidized bed could be a potential high-efficient photocatalytic reactor in wastewater treatment. Such a photocatalytic reactor with bed diameter of 6mm was developed and photocatalytic degradation of methylene blue (MB) was investigated. Mass transfer coefficient of the three-phase mini-fluidized bed was 1.9 and 4.8 times greater than that of liquid–solid mini-fluidized bed and mini-bubble column, respectively. A coupled model based on radiation transfer and reaction kinetics was built. Polychromatic Xe lamp was discretized to obtain the absorbed photons during photocatalytic reaction. The non-uniform radiation field responsible for MB local volumetric degradation rate affected by the scattering and absorption of catalyst particles and micro-bubbles in mini-reactor was solved. Based on mechanism of photocatalytic degradation MB, the reaction kinetics obtained by steady-state hypothesis was coupled into the radiation transfer model. Dispersed mini-bubble flow was obtained by proper operation conditions corresponding to higher apparent quantum efficiency of 0.19%–0.44% also discussed.