| In this thesis, the preparation of the nanocrystalline TiO2 by Ti(O-Bu)4 hydrolyzing was investigated, and TiO2 particles of samples were characterized using TEM, FT-IR and XRD. The obtained particles were globular in shape and its grain size was about 20nm. The photocatalysis activity of the nanocrystalline TiO2 was evaluated by measuring the degradation rate of methyl parathion. The highest rate of the degradation of methyl paration was 62.3%.The surface of the nanocrystalline TiO2 particles was modified with Ag+ ions, clodecyl natrium sulfocalt, stearic acid and silicon oil. The nanocrystalline TiO2 particles modified with stearic acid had higher ability for adsorpting non-polar organic gases in comparing with the original TiO2. The adsorption of methyl parathion on the surface of nanocrystalline TiO2 modified with stearic acid was also studied. The result showed that the amount of the adsorption of methyl parathion on the surface of nanocrystalline TiO2 modified with stearic acid was 1.4 X 10-3mol/g. The adsorption constant is 5.5 X 105 (mol/L)-1.The FT-IR spectra showed that a covalent bond formed between the surface hydroxylic groups and organic long-chain molecules such as stearic acid. Through this kind of chemical reaction, the hydrophilic property of nanocrystalline TiO2 changed into lipophilic property after the nanocrystalline TiO2 particles were modified with stearic acid.. Three methods for the preparation of nanosized TiO2-pesticide complex were investigated. Experimental results showed that the nanosized TiO2-pesticide complex prepared in-situ has highest photodegradation rate. Pesticide residual time in the body of plant was significantly reduced and its biological toxicity increased.
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