Study On The Influencing Factors Of Photocatalytic Degradation Of Formaldehyde By P/TiO₂ In Self-Made Reactor

Nano-sized TiO₂ and phosphor-doped TiO₂ sols were prepared below 100°C using titanium tetrachloride as TiO₂ precursor. The microstructures and optical properties of the as-synthesized TiO₂ sols were characterized by XRD, TEM, UV-vis, and FT-IR spectra analysis. The ability of the product was determined by photocatalytic degradation of methyl orange in sunlight. A new type of intermittent photocatalytic gas reactor system was configured. It was comprised of three parts, a pollutive gas generator, a reactor, and a detector. The generated formaldehyde gas was photocatalytically degraded by P/TiO₂ nano-particles bonded to glass springs, activated carbon fibers (ACF), and the inner surface of the reactor, respectively. The main factors affecting the degradation rate of formaldehyde, e.g. UV light intensity, acidity of catalyst, humidity in reactor, and concentration of formaldehyde, were investigated.The results showed that the TiO₂ and P-doped TiO₂ sols have anatase crystal structures and the colloidal particles were highly mono-dispersed in the sols. The P/TiO₂ was proved to possess a better microstructures and higher photocatalytic activity than TiO₂ sols. The designed reactor system can be used to complete the controlling, detection, and analysis of the main controlling factors which effect the degradation rate of indoor formaldehyde and other volatile organic pollutants were photocatalytic degraded by TiO₂ without large and complex instruments and equipment involved.Photocatalytically degraded under two UV lamps lighting, the formaldehyde could get the maximum degradation rate as 89.42% in 120 minutes when the glass springs were deposited with 11-layer film TiO₂ sol in pH=5 and calcined under 160°C, and the humidity was 50%. The degradation rate of formaldehyde was promoted greatly because of the synergies of TiO₂ and activated carbon fiber. The formaldehyde gas could reach the maximum degradation rate as 96.78% in 120 minutes when ACF was soaked by TiO₂ sol in pH=5 and the humidity was 80%. The formaldehyde gas could reach a maximum degradation rate as 93.00% in 120 minutes when the inner surface of reactor carried TiO₂ sol in pH=7 and the humidity was 50%. To sum up, ACF was the best carrier to TiO₂, the second rank was the inner surface of the reactor, and the glass springs was the worst.