Study On The Preparation And Properties Of Modified TiO₂ Photocatalytic Antibacterial Material

Antimicrobial materials have been extensively used in daily life with people take healthy living and environment seriously. Composite materials with high efficiency antimicrobial and photocatalytic activity have been became researched widely. The TiO₂ and ZnO are semiconductors which can been seen as photocatalyst catalyst, and chitosan is regarded as natural antibacterial. As they all have antimicrobial and purgative activity. It is significant to prepared an environmentally friendly photocatalytic and antibacterial material by the modification TiO₂.In this paper, the nano-TiO₂ photocatalyst with semiconductor ZnO heterogeneous compound and modified with chitosan was synthesized by homogeneous precipitation method and the changing pH of the solution. And the experimental conditions of the material preparation, the photocatalytic degradation of the composite materials on methyl orange and the antibacterial property of the composite materials on coli were discussed. The samples were characterized by XRD, FI-IR, UV-Vis and other analytical methods.XRD showed that semiconductor composite photocatalyst contains the TiO₂ phase and ZnTiO₃, TiO₂ was anatase while the calcining temperature was controled between 450℃and 750℃. TiO₂ combined with ZnO and transformed into ZnTiO₃ with the increase of calcining temperature. It is showed that the band gap of the modified nano-TiO₂ was decreased and the absorption spectrum had shifted to visible area slightly. Chitosan-titania composite material contains the basic structure of chitosan and the TiO₂ exists as anatase while it was calcined under 450℃. It was showed that some peaks of the material moved to lower wave area,which due to the strong hydrogen bonds produced between-OH of TiO₂ and the chitosan molecules.The photocatalytic experiment was performed taking methyl orange dye as photocatalytic degradation objects. We discussed the influence to catalytic properties which comes from the conditions of preparation, light source and the initial concentration of MO and so on. It is showed thatthe experimental conditions of the semiconductor composite photocatalyst were suitablely controled as follows:the titanium salt concentration was 0.15mol·L-1, the total molar ratio between titanium salt and urea was 1:10, and the temperature of water bath was 80℃. The preferable experimental conditions of Chitosan-Titania were that w (CS):w (TiO₂)=1:8, and pH =7. The photocatalytic property of modified TiO₂ was improved under visible light. The photocatalytic degradation of methyl orange with the composite conformed to a kinetic equation according to kinetic analysis. And the reaction rate was decreased while the initial concentration of methyl orange was increased.The antimicrobial performance of the composite was discussed by taking Escherichia Coliform(E.coli) as antimicrobial target with qualitative and quantitative methods. It was discussed the influence on antibactrial activity which come from the experimental conditions, light source, the dosage of samples and so on. The modified TiO₂ composite photocatalyst presented superior antibacterial activity to pure TiO₂ and chitosan. The antibacterial performance of the material was higtly improved. The illumination presented a light influence on the antibacterial activity while it presented certain antimicrobial effects even under dark condition. It was showed that the composite presents obvious antibacterial activity which the bacteriostatic rate can reach 99.57%. The bacteriostatic rate of the composite was enhanced with the desage of the composite increased. The antibacterial rate was more than 99% when the dosage was 3mg/ml.The surface property and the photocatalytic activity of TiO₂ were improved by compound TiO₂ with semiconductor and chitosan.It attributes to the synergism between them by comprehensive analysis of antibiosis and photocatalysis.