Removal of volatile organic compounds (VOCs) by photocatalytic reaction in fluidized bed reacotrs

Abstract

The photocatalytic degradation characteristics of trichloroethylene (TCE), acetone, and toluene have been determined in an annular flow type, an annulus fluidized bed, a circulating fluidized bed photoreactors. The effects of trichloroethylene (TCE) gas flow rate, relative humidity, $TiO_2$ film thickness, and UV light intensity on photodegradation of TCE have been determined in an annular flow type photoreactor. Phosgene and dichloroacetyl chloride formation could be controlled as a function of TCE gas flow rate and photodegradation of TCE decreased with increasing relative humidity. The optimum thickness of $TiO_2$ film was found to be approximately 5 ㎛ and the photocatalytic reaction rate of TCE increased with square root of UV light intensity. The decomposition of TCE by photocatalysis increases with decreasing initial TCE concentration and increasing gas-residence time. The effects of superficial gas velocity $(U_g)$, wavelength and intensity of ultraviolet (UV) light, oxygen and $H_{2}O$ concentration on the photocatalytic degradation of TCE (Trichloroethylene) over $TiO_2/SiO_2$ catalyst have been determined in an annulus fluidized bed photoreactor. The key factor in determining the performance of the annulus fluidized bed photoreactor is found to be an optimum superficial gas velocity $(U_g)$ that provides the optimum UV light transmit through the proper size of bubbles in the photoreactor. The degradation efficiency of TCE increases with light intensity but decreases with wavelength of the UV light and $H_2O$ concentration in the fluidized bed of $TiO_2/silica-gel$ photocatalyst. The optimum concentration of $O_2$ for TCE degradation is found to be approximately 10%. In addition, the effects of the initial TCE concentration, phase holdup ratio of gas and solid phases $(＼epsilon_g /＼epsilon_s)$, CuO loading on the photodegradation of TCE have been determined in an annulus fluidized bed photoreactor. The TCE photodegradation decreased...