Study On Photocatalytic Material Nanometer TiO₂ Prepared By Melt-phase Separation Process

Nanometer TiO₂ is regarded as many better capabilities such as photocatalytic,anti-ultraviolet radiation, self-cleanness, anti-chemical and photocorrosion, which is applied widely in environment pollutant degradation, bactericida, preventing ultraviolet radiation cosmetic. Loaded nanometer TiO₂, compared with singleness power TiO₂, is separated more easily from the liquid and can be reclaimed and reused, so it is valueble in practical application.The sample is prepared that based on Na2O-B2O3-SiO₂ glass system and added fixed TiO₂, which was melted at high temperature, and consequently heat-treated at various temperatures to make glass phase separation as well as crystal TiO₂, finally through the process of acid treating to dissolve enrich alkali, which a photocatalytic nanometer TiO₂ which is loaded firm on porous glass can be obtained. This is called melt-phase separation process. The process that is low-cost of meterail and simple process has broad practical prospect.DTA, XRD, SEM, TEM, EDS is used to research the characteristic of Na2O-B2O3-SiO₂-TiO₂ glass phase-seperation regularity and TiO₂ crystallation action in this system, the relationship between glass phase seperation and TiO₂ crystallation, the effect of adding TiO₂ on phase-seperation of Na2O-B2O3-SiO₂-TiO₂ system, etc.The results have shown: In Na2O-B2O3-SiO₂-TiO₂ glass system, glass phase-separation degree enhances with raising of Na-B content in the composition. Glass phase-separation size becomes bigger while heat-treatment temperature is raised and time is prolonged. It does not change the phase-separation regularity of Na2O-B2O3-SiO₂ glass system but promot glass phase-separation with added TiO₂. Crystallization activation energy of TiO₂ increases with raising the Si-content of compositions. As heat-treatment below 600℃, growth activation energy of TiO₂ is low and the growth speed of TiO₂ grains is faster, but this energy become high as exceed 600℃and the growth speed is slower. Therefore, glass phase-separation promots TiO₂ crystallization, and the size of TiO₂ grains is affected by the phase-separation structure. That is, the bigger glass phase-separation size is, the bigger TiO₂ grains size is. On condition that it ensures to form continual Si-O framework, through choosing compositions that can produce glass phase-seperation and proper heat-treatment system, and consequencely chemical treatment process, anatase TiO₂ crystallization that loaded on porous glass and the size is about 20-50nm can be obtained.Using methyl orange as a degradation material, photocatalytic capability of the TiO₂ is tested by UV /VIS spectrophotometry. The results have shown that the photocatalytic ratio is affected by TiO₂ grains size and porous-glass structure, and the photocatalytic capability is different with different ions and concentrations.