Effect Of Environmental Factors On The Transfer Behavior Of Nano-TiO₂ In Aquatic System

With the development of nano technology, nano-TiO₂ was widely used in the life, this leads to an increase in the water environment of nano-TiO₂. Nano-TiO₂ has been used widely in the field of cosmetics, environmental management and coating for its excellent optical absorption and photocatalytic characteristics. Series of biological effect will occur when nano-TiO₂ released into the aquatic system. Suspension, deposition and transfer behavior for nano-TiO₂ was investigated by changing p H values and adding electrolytes, humic acid and surfactants into suspension liquid. The potential energy equation of nano-TiO₂ particles in aquatic system were simulated by the DLVO theory. And the relative test results were verifed using the potential energy curve. The main results of this study were described as following.In this paper, our research is divided into two parts. The first part is mainly about the the single factor condition on the behavior of nano-TiO₂ in water environment including the regulation of p H, different kinds and concentrations of the surface active agent and electrolyte, and the different concentrations of humic acid（HA）. We found that the isoelectric point（IEP） of the P25 nano-TiO₂ was about 6.8. The particle surface was positively charged when the pH value was lower than IEP, the particle surfaces was negatively charged when the pH value was higher than IEP on the contrary. The more the p H value deviated from the IEP, the more stable of nano-TiO₂ in the aquatic system, and the transfer ability would be stronger.The stability and the transfer ability of nano-TiO₂ could be improved by the adsorption of surfactant cations and surfactant anions produced by the ionization of ionic surfactants sodium dodecyl benzene sulfonate（SDBS）, N-Hexadecyl trimethyl ammonium Chloride（CTAC） and humic acid（HA）.The second part is the two factor conditions on the behavior of nano-TiO₂ in water environmental, including the p H and the surface active agent. It was found that the change of the water environment factor, can change the interaction between nano-Ti O2 particles in the water and influence behavior of nano-TiO₂ particles.According to DLVO theory, simulated the total potential energy curves of nano-TiO₂ particles, and the results were in agreement with the experimental results.