Investigation into Photocatalytic Degradation of Gaseous Benzene in a Circulated Photocatalytic Reactor (CPCR)

Abstract

Due to the fact that suspended TiO 2 powder enjoys free contact with gaseous pollutant molecules in photocatalytic reactors, it can generally achieve better efficiency than immobilized TiO 2 catalysts. However, difficulties with the separation of this catalyst powder from treated pollutants and its re-use often limit its application. Therefore, a circulated photocatalytic reactor (CPCR) was designed to enhance the performance of the photocatalytic degradation of gaseous benzene. TiO 2 film photocatalysts were prepared by the sol-gel method at low temperatures and coated onto the inner wall of this reactor by a bonding agent composed of poly-(2, 2-dimethyl)-acrylic ethylene ester emulsion in which TiO 2 powder was characterized by FTIR, TEM and SEM. In particular, the influences of initial concentration and gas flow rate of benzene on the degradation conversion, D p , apparent reaction rate constants, k r , initial degradation rate, r, and the deactivation and regeneration of catalyst in the CPCR, were investigated. The results indicated that the degradation conversion, apparent reaction rate constants and initial degradation rate were closely correlated to the initial concentration of benzene. To elucidate the factors governing the observations, the adsorption characteristics and kinetics of the photocatalytic degradation of benzene were analyzed using the Langmuir adsorption isotherm and Langmuir-Hinshelwood kinetic model. It was found that the reaction kinetics were best described by a fixed pseudo-first-order kinetic equation of photocatalytic degradation of gaseous benzene in the CPCR.

Adsorption and Photocatalytic Degradation Kinetics of Gaseous Cyclohexane in an Annular Fluidized Bed Photocatalytic Reactor

“…The decomposition of trace contaminants from polluted air using a photocatalytic reactor system has been investigated extensively in the last three decades. − It has been demonstrated that photocatalytic oxidation is a complete and efficient remediation technology in a broad range of pollutants under certain operating conditions at ambient temperature and pressure without any chemical additives. Furthermore, the nanosemiconductor TiO 2 , employed extensively as a photocatalyst, is inexpensive, safe, and very stable with a high photocatalytic activity.…”

Photocatalytic Degradation of a Gaseous Benzene‐Toluene Mixture in a Circulated Photocatalytic Reactor

“…Since the photocatalytic degradation of gaseous benzene in the CPCR has already been investigated [7], the nano-TiO 2 film photocatalyst supported on the inner wall of the quartz glass tube in the CPCR was expected to perform well in the photodegradation of the benzene-toluene mixture. One can derive two conclusions from Fig.…”

“…Many researchers reported that the adsorption of gas follows the Langmuir isotherm [7,15,16] isotherms for the gaseous mixture of benzene and toluene on the catalyst film for 1 h in darkness conditions, under circulation conditions for the mixture concentrations of benzene and toluene at 0.12 and 0.60 mmol L -1 with different proportions in the CPCR, respectively, have been studied.…”

“…A nano-TiO 2 catalyst was prepared by sol-gel method at low temperature using titanium butoxide (Ti(OC 4 H 9 ) 4 (AR, China) as a precursor [7]. In a typical synthesis, 10 mL of titanium butoxide was dissolved in 50 mL of anhydrous ethanol, and pH was adjusted to 2.5 using HNO 3 and recorded by a pHS-3B meter (Shanghai Tianpu Analysis Equipment Co., Ltd., China).…”

“…In recent years, there has been considerable interest in semiconductor photocatalysts for water and air purification and depollution, self-cleaning, and self-disinfecting applications. In particular, the photocatalytic oxidation of benzene [1][2][3][4][5][6][7] and toluene [8][9][10][11][12] in UV-irradiated TiO 2 have been reported by various authors. Kinetics analysis on photocatalytic degradation of gaseous benzene has been reported by Doucet et al [2], Zhong et al [13], and Wang et al [14], respectively.…”