Nanometer Tio <sub> 2 </ Sub> But Aerosol Wet Capture Technology And Performance Investigation

In this thesis, a water based wet sampler was designed and employed to sample nano-TiO2 aerosol according to the principle of wet sampling. Sampler was optimized and updated through the performance test and the Fluent software simulation. And the effects of different collection parameters were studied. Meanwhile, the morphology of nano-TiO2 product and collection suspension was tested, to ensure the chemical and physical characteristic of nano-TiO2 aerosol was not changed by wet sampling. Detailed experimental data and powerful theoretical evidence were obtained for the research and development of wet sampler.Firstly, secondary distilled water was determined to be the best collection fluid by testing the contact angle of nano-TiO2 with variety of solvent. The curve of adsorption and mass concentration of standard samples was made out by using UV spectrophotometer. In additional, the calculation formula of the wet sampler was deduced.Secondly, adopting the principle of wet sampling method, such as negative pressure suction, mist turbulent impinging and liquid sealed face to design a novel nano-TiO2 aerosol wet sampler. The study was found that the fluid inlet with straight angle, diversion net and spray system were helpful to improve the sampling performance. In addition, Fluent software simulation showed that liquid do clockwise eddy movement in fluid reservoir, and the intensity increased with the increase of jet velocity; the collision strength of spray droplets in spray tower increased with the decreasing of diameter and the increasing of height. Simultaneously, the result indicated that the best structure of spray tower was at the height of 150mm and the inner diameter of 60mm; and the optimum parameters were that sampling time was 2h, aerosol flow was 5.5L/min and spray flow was 40ml/min; and the collection efficiency was stabilized around 92%.Finally, the morphology characteristics of nano-TiO2 and collection suspension were acquired through TEM, SEM and laser particle size analyzer. Comparing these results, it was found that the morphology characteristics were not changed, and indicating that this sampler could collect nano-TiO2 aerosol particles effectively and stably. Meanwhile, an interesting thing was found that the reunion of nano-TiO2 was weakened because of the wet sampling and mixing effect.