The Preparation And Characterization Of Kaolinite Substrate Photocatalytic Nanometer TiO₂

Among semiconductor photocatalytic materials which have been deeply studied in recent years, titanium dioxide has been widely used because of many advantages, such as better chemical stability, higher photocatalytic effectiency, cheapness and intoxicity. It can be used to treat polluted water by photocatalytic degradation, purify dirty air, kill bacteria and so on.. Nanometer titanium dioxide has higher photocatalytic efficiency, while usual suspension photocatalysis oxidation has some disadvantages, such as inclination to agglomerate, difficulty to reuse and easiness to cause the second pollution, which seriously limited the application of titanium dioxide. The syntheses of the immobilized photocatalyst that both can enhance its photocatalytic activity and can be reused several times has attracted much attention. By now, many supporters have been studied including ceram, glass, quarts, strainless steel, activated carbon, optical fibre, etc. There are abundant non-metallic mineral resources in China, so combining the photocatalytic technology with mineral will be a promising method.Titanium dioxide photocatalyst supported on kaolinite was prepared by sol-gel method. Hydrolysis temperature, hydrolysis time, drying temperature, calcinations temperature, ore pulp density and other factors, which effect the photocatalytic activity of TiO2/kaolinite were studied in this paper. The optimal reaction condition can be decided that: hydrolysis for 4h at 37℃, drying for 1 h at 80℃, calcinations for 3 hours at 550℃.Modern testing methods to study nanometer titanium dioxide on the surface of kaolinite were also employed in this study. It can be seen that titanium dioxide appeared in different crystal forms at different temperature of calcinations by using of XRD. TEM photos of TiO2/kaolinite can prove that the titanium dioxide, 5~10nm particles, had been loaded on the surface of kaolinite successfully and homogeneously. It can be seen that the titanium dioxide connected with Kaolinite by Ti-O-Si band by IR, and the atoms on the surface of TiO2/kaolinite can be detected by XPS. Adding the help of Laman spectrum, it can be concluded that the titanium dioxide was successfully loaded on the surface of kaolinite in the form of rutile.To evaluate the photocatalytic activity of TiO2/kaolinite, which were used to degradate the analogue dye wastewater(acid-red) and actual dye wastewater(azo ).From the results of the experiments, it can be known that TiO2/kaolinite compound photocatalytic prepared by sol-gel method had high photocatalytic activity not only to analogue dye wastewater but also to actual dye wastewater.TiO2/kaolinite compound photocatalytic with uniform particles and high chemical activity was prepared at relatively low temperature (hydrolysis 4h at 37 drying lh at 80 ) in sol-gel method. Under UV light, photocatalytic decolor rate of analogue dye wastewater (20mg/L) is 82.44%, and the rate of actual dye wastewater(azo). is 91.67% , This study set the stage of theory and practice for further research of TiO2/kaolinite compound photocatalytic.