The Application Of Photocatalystic Bactericidal Technology Of Nano-TiO₂ In Water And The Investigation Of The Bactericidal Mechanism

Titanium dioxide nano-crystal photocatalystic technique is one of the new technologies to control environment pollution. It can effectively degrade the organic pollutants into small inorganic molecules. Several researches in medically field have been investigated and indicated this technique not only can kill bacteria but also can removal endotoxin when bacteria died.A study was conducted to investigate the method of making nano-TiO2 photocatalystic agent and discusses the mechanism of photo-induced bactericidal activity against bacteria in water with this agent, with the aim to control the quality of aquaculture water.The experimental results of the immobilized nano-TiO2 experiment in glass layer indicated that the sol-gel method was a good method for immobilizing nano-TiO2 photocatalystic agent. The proportion of TiO2 sol and treatment temperatures must be limited in preparation process. The bacteria killed experiments show that the agent can inhibit bacteria effectively. The activity of killing specific bacteria by nano-TiO2 was depended on the sizes of TiO2 particles. In the process of killing Pseudomonas aeruginosa, the film with TiO2 showed high activity when the thickness of TiO2 layer was 8.18 nm (See B treatment group). However, the inhibitory activity against Bacillus subtilis by nano-TiO2 reached high when the thickness of TiO2 layer was 12.51nm (See B treatment group). The photo-sterilization activity of B treatment group is higher activity than other treatments.The photo-induced bactericidal mechanism was discussed. The electron-holepair of nano-TiO2 was stimulated by ultraviolet light. It can act with DO (dissolve oxygen) and H2O, then produce hydroxyl radical ( OH) which can inactivate microorganisms by decomposing their phospholipid and protein.