Photocatalytic oxidation of benzene, toluene, ethylbenzene and xylenes (BTEX) by titanium dioxide (TiO₂) cementitious materials for air pollution control

Abstract

Cementitious materials with active photocatalytic agents have been applied on external surfaces of buildings for self cleaning and self-disinfecting purposes. Recently, active photocatalytic agents such as TiO2 have been used in road pavement concrete as an innovative technology for the control of roadside air pollution. There is currently not much information available on the implementation of TiO2 active pavements for the removal of hydrocarbon pollution. In this study, degradation of benzene, toluene, ethylbenzene and xylene (BTEX) in air by TiO2 active concrete slabs were investigated in a laboratory-scale reactor. Environmental variables studied included relative humidity (RH), air flow rate, aging and UV intensity. BTEX concentrations in inlet and outlet air samples were analyzed using a gas chromatograph with photoionization detector. The optimal RH for BTEX mass removal was approximately 50% with decreasing mass removal for lower or higher RH. Percent removals of BTEX were found to decrease with higher flow rate but mass removed increased with air flow rate. Similarly, an increase in UV intensity from 5 to 12 W/m2 resulted in an increase in mass removal. Overall, it appeared that TiO2 active materials may be used as a passive technology in mitigating air pollution from motor vehicles.