Study On Dispersionandthe Surface Modification Of Nanometer Titanium Dioxide

According to the properties of small particle size, large specific surface area, photo-catalyticactivity, strong UV absorption,Nano-titanium dioxide is widely used in sewage treatment, airpurification, anti-bacterial toxin, cosmetics, additives, self-cleaning, anti-fog and anti-dew, etc.Nano-titanium dioxide is currently the most popular photo-catalytic material. But the smallparticle size, large specific surface area, high surface energy make nano-titanium dioxide in anon-thermodynamic stable state and it is very easy to reunite and greatly influence its application.So it is necessary to carry out surface modification of nano-titanium dioxide. This paper studiedthe effect of surface modification of nano-titanium dioxide with the different dispersing agentsand silane coupling agent. The optimum process conditions of modified nano-titanium dioxidewas characterized by gravity sedimentation, particle size test, Zeta potential and the photo-degradation rate of MB.The first part of this paper, we explored the effect on the dispersion and stability ofnano-titanium dioxide in aqueous medium with different dispersing agents, characterized bygravity sedimentation and particle size test. The experimental results showed that the best pHvalue and content of sodium hexametaphosphate, ethylene glycol amine, polyethylene glycol400is respectively6,10,2, and0.02-0.08g,0.05g,0.02-0.06g.The second part of this paper investigated the influence of surface modification onnano-titanium dioxide with gamma urea propyl triethoxy silane coupling agent. The differentreaction conditions such as pH, the content of silane coupling agent, reaction temperature andreaction time, were studies to determine the optimal technological conditions. The results was that pH value4, the content of silane coupling agent0.5%, reaction temperature60℃, reaction time1h.The average size of nano-titanium dioxide in liquid dispersion was about76nm and the rateof photo catalytic degradation of MB solution was97%.The third part discussed the effect of surface modification on nano-titanium dioxide withsurface active agent PEG400and gamma urea propyl triethoxy silane. PH value, silane couplingagent dosage, reaction temperature and reaction time were studied. The results showed that theaddition of surface active agent PEG400could optimize the conditions of surface modification ofnano-titanium dioxide with gamma urea propyl triethoxy silane. It’s pH value4, the content ofcoupling agent0.5%, the reaction temperature at room temperature and the reaction time1h. Theaverage size of nano-titanium dioxide in liquid dispersion was about65nm and the rate of photocatalytic degradation of MB solution was98%.