The Study On Preparation Of Nanosized TiO₂ Immobilized To Diatomite Particles And Degradation Process Of Formaldehyde

The nano-sized titanium dioxide immobilized onto diatomite was obtained through changing the TiOSO4 concentration, the quantity proportion between diatomite and TiO₂, the concentration of urea, pH, reaction temperature and time, calcining temperature by the mixed homogeneous deposition method using the carrier of diatomite,the raw material of TiOSO4 and the precipitator of urea The obtained photocatalyst were characterized by SEM and XRD and it was concluded that the best preparing conditions were as flowing: the incipient concentration of TiOSO4 was 0.01mol/L, the quantity ratio between diatomite and TiO₂ was 2:1, the concentration of urea was 0.1mol/L, the pH of reaction system was 1.5, the reaction temperature was 75℃, the reaction time was 60 min and the calcining temperature was 700℃. Under the best preparation conditions, the max loading rate of nano-sized titanium dioxide was 75%, and the average diameter of loaded particle was 150nm. We also probed to the binding mechanism of titanic dioxide particulate and the diatomite carrier.The experiment of degrading formaldehyde was did using the sample that was made out under the best preparation conditions.The residual quantity of formaldehyde was mensurated by the gas chromatograph through changing the raw concentration of formaldehyde injected into the reactor, the reaction temperature of reaction system, the light intensity and the relative humidity of atmosphere in the reactor on principle of the practical environment conditions. It came to the conclude as follows: the sample we made could oxidate completely the high concentration of formaldehyde under uninterrupted illumination and 5 gram of our sample could decrease 99 pensent of the formaldehyde with raw concentration of 6.0×10-3mg/L in 150 hours; the higher temperature, the rapider rate of degrading the same quantity of formaldehyde, as witch it cost 50 hours for 5 gram of sample oxidating formaldehyde with raw concentration of 2.0×10-3mg/L completely under 15℃, but cost 12 hours under 45℃; the stronger light intensity, the rapider rate of degrading the formaldehyde, as witch it cost 14 hours for 5 gram of sample oxidating formaldehyde with raw concentration of 2.0×10-3mg/L completely under the light intensity of 8100Lm/m2, but it nearly could not degrade the formaldehyde under 0 Lm/m2; the more relative humidity, the faster our sample degrading the formaldehyde, as witch 5 gram of our sample oxidated formaldehyde with raw concentration of 2.0×10-3mg/L to 3.72×10-5mg/L in 14 hours under the relative humidity of 50%, but to 1.0×10-5mg/L under the relative humidity of 80%.