Preparation And Application Of (Zn～(2+), Yb～(3+)) Co-Doped TiO₂ Nanosized Composite Coatings

To enhance the dispersion ability of nanoparticles in water coats, bactericidal performance and photocatalytic oxidation of formaldehyde in gas-phase, this dissertation exploites an environmental function coatings, which is security, high efficiency, economy and green and provides essential technical support for industrial production of the environmental function coatings.A two-step process crafts is adopted to prepare a noval environmental function coatings by applying (Zn²⁺, Yb³⁺) co-doped TiO₂ nanoparticles into polystyrene-acrylic acid coating latex so as to enhance the dispersion stability of titania nanoparticles and improve weather resisting property of coatings. The optimal conditions found are as follows: grinding dispersion for 0.5 h; organic dispersant agent 3275 of 1% (wt, 3275/H₂O) at pH 8.0; nanoparticles of 1% (or 2% chosen according to actual requirements for weather resisting property of the coatings). Analysis of TEM shows that the radius of the particles in membrane is 30nm with good dispersion ability. Resistance to water, resistance to alkali and resistance to washing of modified TiO₂ composite nano-coatings all reach national first quality standard. The amount of nanoparticles should be 1～2% when the requirement for resistance to ageing is low in order to strengthen the environmental function.The results of degrading formaldehyde by nano-sized composite coatings demonstrates that (Zn²⁺, Yb³⁺) co-doped TiO₂ nanocoatings can treat formaldehyde in air effectively. Different wavelengths of ultraviolet (254nm or 365nm) were not observed to affect formaldehyde degradation significantly. When the initial concentration of formaldehyde in air is 178.26 mg/m³, photo-degradation rate of formaldehyde on the coating surface reaches 95.8% after 156 h of photocatalytic reaction. When the relative humidity in air is 64%RH, photo-degradation rate of formaldehyde on the coating surface is higher. The photocatalytic degradation of formaldehyde in gas-phase on the coating surface was approximately consistent with the first-order kinetics.The results of bactericidal performance of the nanoparticles on Escherichia coliform, Staphylococcus aureaus Bacillus subtilis and Pseudomonas aeruginosa...