Finishing Of Cotton Fabrics With Aqueous Nano-TiO₂ Dispersion And Decomposition Of Gaseous Ammonia Under UV And Visible Light Irradiation

Nano-TiO₂ has plenty of excellent properties and has been used widely in the field of industry and other special areas. But nano-TiO₂ also has many shortages, for example the stablity of water dispersion is poor, which limit the application of nano-TiO₂ in textile industry. So it's necessary to develop a new method for the dispersion of nano-TiO₂ in water solutions.In recent years, the new application of nano-TiO₂ is being developed continually. Study on nano-TiO₂ composite agents has become hotspots of research. Now it's well known that nano composite agents can be more useful than conventional chemical agents. In this paper, nano-particles were added onto fabrics to prepare the nano-TiO₂ composite fabrics, which have the ability of photodegradation of various pollutions. Firstly the technology of dispersion of nano-particles was studied, and the optimal species and quantity of dispersion agent were determined. Nano-particles were dispersed in water solution, and then add the poly-glycol dispersion agent and stable agent, the solution dispersed ultrasonic for some time at room temperature, so nano-TiO2 composite agent was prepared. The agent was examined with the apparatus as spectrophotometer, granularity meter, STM(scanning tunnel microscope)and TEM(tunnel electron microscope). The results shew that the dispersibility of nano-particles became excellent after treated with 0.25% poly-glycol dispersion agent, the average dimension of treated nano-particles in dispersion is about 25nm, and no big agglomerated particles occur in agent.Nano composite fabrics were prepared with two methods, which were padding or coating nano TiO₂ composite agents onto fabrics. The status of nano-particles on the surface of nano-fabrics was determined with SEM(scanning electron microscope) and XRD(X-ray Diffraction), the result displayed that the dimension of nano-particles on the fabric is within the range of nanometer , and no big agglomerated particles occur. The whiteness and strength of fabrics change slightly when the concentration of nano TiO₂ composite agent is low, however, the change is evident as the concentration of agent enlarged. The effluence of nano-TiO₂ composite agent to the color of fabrics dyed with various dyes is visible, obviously at the maximum absorbence wavelength the K/S value reduces largely after the fabrics treated with nano-TiO₂ agents, and theextent of effluence is various as the type of dye.Photocatalytic degradation of ammonia with nano composite fabric under the illumination of ultraviolet was influenced by many factors, such as the type of chemical auxiliary added into nano T1O2 composite agent, flux of air, concentration of ammonia in the air and relative humidity of air. The photocatalytic degradation rate of ammonia enlarges as the hydrophile of chemical auxiliary increasing, and the degradation rate is high when flux of air, concentration of ammonia in the air and relative humidity of air are moderate.Nano TiC>2 composite agent also can be sensitized by some dyes, then which was used to prepare nano composite fabrics which can photocatalytic degrade ammonia under visible light. Photocatalytic degradation of ammonia with nano composite fabrics dye sensitized is feasible, but degradation rate of ammonia is low relatively.