The Study On Preparation, Characterisation And Properties Of TiO₂-Diatomite Nanocomposite

Nano-TiO2 has the specialities of high activity, chemical stability, anti-chemical and anti-photochemical erosion, no toxin in photocatalytic field, So it has the greatly potential worth in sewage disposal, air cleaning, and so on. Nevertheless nano-TiO2's bandwidth is 3.2eV, so it can only absorb the UV light that has the wavelength shorter than 388nm, which has a low utilizing ratio to sun light. The respond range of sun light can be widened by nano-TiO2 modified, for example, metal and non-metal doping, light sensitization with organic dye, etc.And it can prohibit the compoundation of electron an cavity started by the light, so it can enhance the photocatalytic efficiency. Other the wise nano-TiO2 has the big disadvantage that it will reunite easily, reclaim hard for its small particle. In order to overcome the problem, nano-TiO2 was often put on the carrier now, which can reduce the cost also.So it is tend to industrialization and practical application.Therefore, the mix-crystal nano-TiO2 which has the similarity function to metal oxidation coupling that can improve the photocatalytic effect for enhancing the spectrum responding range was prepared by two step hydrolyzation at constant pressure. Nano-TiO2/diatomite composite was prepared by two methods, emulsion dipping and directly depositing. It can resolve the disadvantage of surface effect for the surface decreasing after compounding, and also can be reclaimed for the repeating utilizing. Structure characterization showed that the TiO2 was composed of anatase and rutile which has the ratio:A:R=2.7:1,and the grain diameter was 12nm, TiO2 dispersed on the surface of diatomite and around the hole, so diatomite prevented the growing up of TiO2, and it compensated the adsorption decrease for its many hole structure. EDS showed that the TiO2 can't be put onto the diatomite sufficiently by emulsion dipping method, and it tends to form over-packed structure for the TiO2 mainly depositing on the surface of the diatomite, whose photocatalytic capability is under the composite by directly depositing method. IR spectrum showed that there has some Ti-O-Si chemical bond which increase the composite's stability, and is favor for the separating of electron-cavity produced by light, so it enhanced the photocatalytic efficiency.The experiment that nano-TiO2/diatomite composite photocatalyticly degrade the scarlet 3R was studied with the sun light, compared the adsorption and degradation effect with the water quantum in the composite preparation, the ratio of TiO2 and diatomite, the pH of dye solution, dye concentration, and the re-utilize time after time. Make the conclusion that the catalyzer photocatalyticly degrade the scarlet 3R was take place at the surface of catalyzer, which was firstly adsorbed and secondly degraded. Put forward that the photocatalyzing reaction accorded with zero-order equation in dynamics.