Synthesis Of TiO₂/bentonite Compound Photocatalytic Material By Microwave Irradiation And Study Of Its Photocatalytic Activity

The TiO2 /bentonite compound photocatalytic materials have been proved to be one of the most interesting semiconductor materials at home and abroad. They are widely used in the fields such as photocatalytic oxidation, catalysis, catalytic supports, selective sorbent, molecular screen, electrochemistry and optical element for their good properties of large BET surface area, porosity and large surface activity. In this paper, we used Liaoning's modified bentonite with sodium compounds as carrier to prepare TiO2 /bentonite compound photocatalytic material by microwave irradiation methods. With the help of experimental techniques, such as X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectra, specific surface areas determination, we studied systematically the compound photocatalyst, the characteristics of photocatalysis for treating Rhodamine B and the possibilities of their regeneration. The main contents and results of this paper are included as following:Firstly, this paper investigates the influential factors of preparation of TiO2 /bentonite compound photocatalytic material by microwave irradiation. The optimal conditions of preparation of microwave synthesis are 230 w for microwave heating power, 5 min for microwave heating time, 500℃ for calcining temperature, 2.5 h for calcining time. The results of orthogonal experiment verify the accuracy of single factor experiment, and conclude the influential sequence of influential preparation factors for photocatalyst: microwave heating power > microwave heating time > calcining temperature. X-ray diffraction tells us that the characteristic peak of TiO2/bentonite compound photocatalytic material on 001 surface disappears, which is calcined 500℃, and anatase diffraction peak appear at d = 3. 4984A, whose crystallization degree is fine. By Fourier transform infrared spectra, we find out that Titanium ion component takes place thechemical bond with the bentonite crystalline structure of the carrier really. Specific surface area analysis founds that the specific surface area of TiO2 /bentonite compound photocatalytic material is much larger than bentonite and sodium modified bentonite.Secondly, we systematically study the influential factors, by TiO2 /bentonite compound photocatalytic material degrading simulation dyestuffs Rhodamine B of waste water. The optimal conditions of catalysis degrading are 16 g/1 for dosage of TiO2 /bentonite photocatalytic material, 20 mg/L for initial concentration of solution of Rhodamine B, natural pH value of initial solution pH, 20 L/min for air flux, 1 h for reaction time, 0.2 mmoL/L for oxidant's (H2O2) consumption. Moreover, the waste water containing dye and Cr6+ were treated respectively by T1O2 /bentonite compound photocatalytic materials. The results indicate that the removing rate of CODcr from dye waste water and Cr6+ from electroplating waster water is increased significantly relative to the starting materials, and the removing rate is larger than activated carbon.Finally, through the calcining experiment, we explore the recycled conditions of T1O2 /bentonite compound photocatalytic material. The optical conditions of regenertation are 300 for calcining temperature, 1 h for calcining time. In addition , the decoloring rate of catalysis degrading Rhodamine B is 90.56% and the losing rate is 2%, after regenerated 2 times; X-ray diffraction tells us that the characteristic diffraction peak of anatase of the recycled material does not have too great change, when calcining temperature changes from 300 to 800, which Indicates that this material has very good repeated recycled performance.