A Study On Preparation Of TiO₂-ACF And Its Adsorption And Degradation Properties For Formaldehyde

The removal of formaldehyde pollution is a hot scientific topic, and indoor formaldehyde at low concentrations, is particularly intractable. TiO2 is an effective photocatalysis, and activated carbon fiber (ACF) has good absorption properties, thus TiO2 -ACF composite materials combining the advantages of both TiO2 and ACF have excellent properties for the removal of formaldehyde.TiO2 nano-material is prepared by sol-gel method and modified with Fe3+ which can enhance photocatalytic activity of TiO2. In order to get a highly activated photocatalyst, some preparation factors such as the the iron ion content, calcination temperature and calcination time effects, have been studied. The results show that there is relationship among the content of iron, calcination temperature and time. Through a set of orthogonal experiments, the relationship of the three factors during the preparation of TiO2 is explored, which shows that the iron content is the most important factor. Optimal parameters are the iron content of 1.5wt%, calcined at 450℃and calcined time for 3h.The process of coating TiO2 on activated carbon fiber is studied. The higher of the content of TiO2, the smaller of the specific surface area of TiO2-ACF.TiO2-ACF materials with TiO2 content of 26wt% have higher oxidation resistance and higher surface area, thus have the better removal ability of formaldehyde. The different light intensities and wavelengths, as well as different initial concentrations of formaldehyde are also studied. The results show that, the greater the light intensity, the shorter the wavelength, also the lower the initial concentration of formaldehyde, the better the treatment effect. TiO2-ACF is reusable. After reused four times, this material still process high formaldehyde degration rate reaching up to 80%.Finally, the apparent kinetic equation of degradation is proposed. The degradating reaction conforms to first order reaction when the initial concentration of HCHO is lower(1.3 mg/m3-7.68 mg/m3); on the contrary, the degradation reaction is zero order reaction when the initial concentration of HCHO is higher(23.34 mg/m3-34.12 mg/m3).