Formation of Formaldehyde and Other Byproducts by TiO2 Photocatalyst Materials

Photocatalysts promised to control pollution in an environmentally benign manner, inexpensively, and with a low or cheap energy input. However, the limited chemical activity of photocatalysts has prevented their widespread use. This limitation two important consequences; addition removal efficiency for pollution, may also generate unwanted byproducts due incomplete reaction. study focuses on formed photocatalytic degradation dimethyl sulfide (DMS) titanium dioxide (TiO2), using continuous flow reactor detection via proton transfer reaction mass spectrometry. TiO2, activated carbon (AC), TiO2/AC (1:1) (1:5) were tested either laser-driven light source LED lamps at 365 nm. The samples characterized N2-BET surface area pore size distributions, Scanning Electron Microscopy, X-ray Diffraction, Photoelectron Spectroscopy, which confirmed that TiO2 was successfully coated without unexpected phases. showed different mechanisms DMS. maximum yield formaldehyde, 11.4%, observed DMS reacting composite operating 31.7% 50 ?C. In formaldehdye, significant products included acetone disulfide. all, accounted over half material removed from airstream. composites have lower than but higher byproducts. Experiments conducted 20 ?C 70 as temperature increases, decreases production increases even more. is attributed both decreased high temperatures increased recombination reactive species, residence time volatile compounds hot surface. shows potentially dangerous are by reactors because under conditions generally employed.