[Photocatalytic degradation of low level formaldehyde on TiO2 porous film].

Photocatalytic degradation of low level formaldehyde in the gas phase was studied in a intermittent recirculation photocatalytic reaction system with TiO2 porous film photocatalyst coated on stainless steel mesh. The effects of carrier of the photocatalyst, coating cycle of the photocatalyst, the initial concentration of formaldehyde and the illumination source were investigated respectively. The study of the aging stability of the photocatalyst was carried out as well. Results show that the degradation efficiency of formaldehyde increased with the increase of mesh number. The degradation efficiency also increased with the increase of carrier number, but the influence of carrier number on the degradation efficiexcy was gradually weakened with increasing carrier number. The activity of the photocatalyst firstly increased and then decreased when coating cycle increased from 1 cycle to 6 cycles. When initial concentration was in the range of 1.34 - 10.72 mg/m3, the change of formaldehyde concentration markedly increased with the increase of initial concentration, but the degradation efficiency increased and subsequently decreased with increasing initial concentration. The degradation efficiency with germicidal light was approximately 19.0% higher than that with black light holding same power, and the enhancement in light intensity could approximately increase the degradation efficiency by 20.5%. Finally, the experiment on the longevity of the photocatalyst indicated that the photocatalyst had the good photocatalytic activity after being used for 4 cycles.