Influencing Factors Of Formaldehyde Photocatalytic Degradation By P-TiO₂ Loaded On Papers

the World Health Organization (WHO), and also a recognized source of allergy and potentially one of the strong mutagen. Formaldehyde was a high toxic substance, which was listed in the second place in our state toxic chemicals priority to control. In this paper, the TiO₂ sol and the P-TiO₂ sol were prepared at low temperatures when TiCl4 was as the main raw material, and the products were characterized by methods of XRD, TEM, UV-vis and FT-IR, respectively. The degradation rate of methyl red solution was also tested; low concentrations of indoor air pollution-formaldehyde gas was degradated by the TiO₂ sol and P-TiO₂ sol loaded on the kraft paper, cigarette paper and coated paper; various reaction factors influencing the degradation rate of formaldehyde gas were studied by tentative experiments, orthogonal experiments and single factor experiments respectively, and its reuse rate was also explored on this basis.The results showed that the crystal structures of nano-P-TiO₂ and nano-TiO₂ prepared by sol-gel method were anatase phase and a good dispersion; the test experiment results of methyl red solution indicated that P-TiO₂ sol compared with nano-TiO₂ sol demonstrated more obvious advantages in microstructure and photocatalytic properties; preliminary degradation results of formaldehyde gas revealed that P-TiO₂ photocatalyst loaded on the kraft paper was prior to TiO₂ photocatalyst in photocatalytic degradation of formaldehyde gas under the same conditions, and the degradation rate increased nearly 20 percentage points relatively; the tentative experimental results proclaimed that the following factors such as the initial concentration of formaldehyde, the humidity of ambient conditions, pH value, reaction time and the impact of metal ions added had played a key role in the degradation experiments of formaldehyde gas, which were also served as comprehensive factors surveyed in orthogonal experiments properly; the single fartor experimental results indicated that the best pH of TiO₂ sol was about 5.50, and the best humidity of the reactor was close to 55%, and the best initial concentration of formaldehyde gas was about 3.00 mg/m³; the verification test results of orthogonal experimental indicated that the degradation rate of formaldehyde gas could reach 97.39%, whose concentration decresed from 3.08 mg/m³ to 0.0803mg/m³ when pH value of the sol loaded on kraft papers was about 5.50, the humidity was about 55% in the reactor, the initial concentration of formaldehyde gas was 3.08mg/m³, the added volume of Cu²⁺ ions was 6.00mL, and reacted for 120min under UV irradiation; the reuse experiment results displayed that the degradation rate of formaldehyde gas was 48.08% when the photocatalyst loaded on papers was used once time, and the degradation rate is 21.52% when was used twice, and the degradation rate of the three times was 3.69%.