[Studies on the dispersion and deposition behavior of nano-TiO2 in aquatic system].

The existing form and environmental behavior of nTiO2 in aquatic system are mainly affected by environmental factors. The dispension and deposition behavior of nTiO2 was investigated by changing pH values of the suspension liquid and adding electrolytes and surfactants using P25 nano-TiO2 as the research object. The results indicated that the pH value obviously affected the stability of nTiO2 by changing the charge distribution on the nTiO2 particles. TiO2 nanoparticles were highly aggregated to deposit when the pH value was close to the isoelectric point. The characteristic adsorption ion of AlCl3,CaCl2,NaCl and Na2SO4 after ionization on the surface of nTiO2 particles varied from each other. The adsorption of cations neutralized the negative charge on the surface of nTiO2 particles which led to the quick aggregation and deposition of nTiO2 particles. The adsorption of anions improved the stability of nTiO2 particles in water by increasing electrostatic repulsion between TiO2 particles. Surfactants would adsorb onto the surface of nTiO2 particles and enhance the stability of nTiO2 by changing the surface properties of the nanoparticles. The potential energy of nTiO2 particles were simulated by the DLVO theory. The simulative potential energy curve confirmed that the change of relevant water environment conditions led to the change of potential energy of nTiO2 particles,which determined the dispension and deposition behavior of nTiO2 particles.