Degradation of acetaldehyde by Ag/TiO2 photocatalyst coated on polyester air filter

Abstract

Acetaldehyde is a toxic mainstream in cigarette smoke. This study aims to apply Ag/TiO2 coated on a polyester air filter (PET) to degrade acetaldehyde. Ag/TiO2 was prepared by doping 10 mol% of silver (Ag) on TiO2 via impregnation method. The crystallinity and wavelength absorption of Ag/TiO2 particles were characterized by X-ray Diffraction (XRD) and UV-vis NIR spectrophotometer, respectively. Then, the Ag/TiO2 particles were mixed with two different binders such as Polyethylene glycols (PEG, Mw = 6,000 g/mol) and Polyacrylic acid (PAA) before coating on PET filter by dip-coating technique. The percentages of binder were varied from 0.3, 1, 3 and 5wt% by weight of photocatalyst particles. The photocatalytic activities of PET filters coated by Ag/TiO2 with different binders were examined by decolorization of 10−5 M methylene blue (MB) solution and degradation of acetaldehyde under visible light irradiation. The XRD results indicated that Ag/TiO2 had the combination of anatase phase, silver oxide (AgO) and metallic silver (Ago). After doping, the band gap energy of TiO2 was reduced from 3.28 eV to 3.22 eV (red-shift effect). The PET filters coated with 5% PEG-Ag/TiO2 and 3% PAA-Ag/TiO2 showed the MB decolorization efficiency of 88 % and 87%, respectively. The photocatalytic degradation of acetaldehyde was carried out by 3%PAA-Ag/TiO2. The degradation efficiency of acetaldehyde by 3%PAA-Ag/TiO2 filter was 96% within 96 h. The concentration of CO2 which was a product of photocatalysis increased simultaneously during the reaction. This was an evidence that acetaldehyde was degraded by the photocatalytic air filter.