Synthesis And Visible Light Photocatalytic Activity Of TiO₂-Carbon Black

Heterogeneous semiconductor photocatalysis is a popular technical that has great potentialto solve pollution and utilize solar energy. Among various oxide semiconductors, titaniumdioxide （TiO₂） has been the most popular photocatalyst due to high photo-oxidation power,excellent stability, non-toxicity, and low material cost. The applications of TiO₂photocatalysisoxidation technology have extensive application prospects in the development of new energyand environmental protection area. While the current TiO₂photocatalyst have a series ofproblems for the industrial applications of TiO₂photocatalyst, such as, low photocatalyticactivity, low utilization ratio of visible light, hard to loading and recycling etc.Based on our previous research work, combining with literature review, using titaniumpowder as a metal source, micron carbon black and nano carbon black as the reactive carbonsource, the intermediate product TiC-carbon black were successfully synthesized in a KCl-LiClmolten salt reaction medium in this thesis. Then, the TiO₂-carbon black were prepared byoxidizing the intermediate product TiC-carbon black in a flowing air atmosphere. The crystalstructure, phase composition, surface morphologies and optical absorption behavior of theTiO₂-carbon black catalysts were characterized by XRD, SEM, TEM, UV-Vis and Ramanspectroscopy. The effects of reaction temperature, the molar ratio of carbon black to titaniumpowder in a molten salt medium as well as oxidation temperature of TiC coated carbon black onthe crystal structure and properties of the prepared TiO₂-carbon black photocatalyst was alsoinvestigated. The photocatalytic activities of TiO₂-carbon black catalysts were investigated withthe methylene blue water solution as a target pollutant. The main conclusions are as follows:1. Using micron carbon black as the reactive carbon source and the molar ratio betweencarbon and titanium2/1（C/Ti=2/1）, TiC-micron carbon black composites synthesized at750oCfor3hours in molten salt reaction not only maintain the basic particle morphology of microncarbon black, but also the homogeneous and dense TiC coatings composed of particles wereformed on the surface of the micron carbon black. Meanwhile, using nano carbon black as thereactive carbon source and the molar ratio between carbon and titanium1.25/1, TiC-namocarbon black composites synthesized at750oC for3hours in molten salt reaction also canmaintain the basic small particle morphology of nano carbon black and have no residual metaltitanium.2. The oxidation temperature has a great influence on the structure and component of theTiO₂-carbon black. In this paper, the TiO₂-carbon black was abtained by oxidising theintermediate product TiC-carbon black and the TiC-carbon black formed by the compoundprocess were composed of titanium and rutile, but mainly was the titanium phase. And the experiment results show that the higher the oxidizing temperature, the bigger of the drivingforces of TiC change to TiO₂, and the more beneficial to the growth of crastal grain, but at thesame time the particles will more easily to bond together.3. Methylene blue was used as a model compound to investigate the photocatalyticperformance of the TiO₂-carbon black composites in this paper. The results show that theremoval rate of methylene blue of synthesized TiO₂-micron carbon black can is more than64%in6hours under visible light. Meanwhile, the removal rate and degradtaion rate of methyleneblue of synthesized TiO₂-nano carbon black in6hours are65%and41%in6hours undervisible light.