Photocatalytic destruction of air pollutants with vacuum ultraviolet (VUV) irradiation

Photocatalysis with vacuum ultraviolet (VUV) irradiation (VUV–PCO) was utilized to destroy air pollutants. Escherichia coli (E. coli) and toluene were chosen as the target pollutants. Two parallel reactions with 254 nm UV irradiation (254 nm-PCO) and without TiO2 (i.e. VUV photolysis) were also conducted for comparison. Results indicate that VUV–PCO process has a higher efficiency in destroying toluene and inactivating E. coli. In addition, the stability of PCO activity is increased while the byproducts yield is lowered during toluene destruction in the VUV–PCO process. Toluene removal efficiency (TRE) in the VUV–PCO process was more than 5 times higher than that in the 254 nm-PCO process. VUV–PCO overcomes some drawbacks of conventional photocatalysis, such as low efficiency and easy photocatalyst deactivation. The destroying mechanism of air pollutants in the VUV–PCO process is greatly different from that of the 254 nm-PCO process. The excellent performance of VUV–PCO system may be attributed to the more reaction processes (such as VUV photolysis and catalytic ozonation) and more reactive species (such as active oxygen and hydroxyl radicals) formed to destroy the pollutants.