【作者】 颜昌利；

【导师】 司士辉；

【作者基本信息】 中南大学 ， 分析化学， 2004， 硕士

【摘要】 本研究以钛酸丁酯为原料，采用水解法制备纳米TiO₂。在钛酸丁酯／乙醇为1：5，钛酸丁酯浓度为0.25mol／L，搅拌时间为1h的条件下，水解完后放置1d，65℃在干燥箱中烘干，700℃煅烧1h，制得直径约为20nm的纳米TiO₂。采用TEM、XRD、IR等手段对不同煅烧温度制备的纳米TiO₂进行表征，结果表明800℃以下的不同温度煅烧后的TiO₂分散都很好，颗粒较小，粒度分布较均匀，其光催化活性高。当煅烧温度低于700℃时，TiO₂粉末的晶粒与颗粒增长缓慢。当煅烧温度高于800℃时，TiO₂晶粒迅速增大，且是纯金红石型，晶粒大则比表面积小，导致被降解有机物农药在TiO₂表面吸附量减少，其活性降低。以甲基对硫磷为对象研究用钛酸丁酯水解法制备的纳米TiO₂的光催化活性，研究表明1×10^-4mol／L的甲基对硫磷在加入0.2g所制得的纳米TiO₂后，光催化降解1h的降解率为62.3％。 采用压电石英微天平（QCM）现场技术研究极性和非极性有机物在纳米TiO₂和改性后的纳米TiO₂上的吸附行为。实验研究表明：Ag⁺、硅油、硬脂酸、表面活性剂都能提高纳米TiO₂对非极性有机物的吸附，其中硬脂酸和硅油的增强效果最为明显。对农药甲基对硫磷在改性前后的纳米TiO₂上的吸附研究表明，表面亲脂处理后的纳米TiO₂对非极性农药的吸附有明显提高。甲基对硫磷分子在亲脂处理后的纳米TiO₂上的吸附符合Langmuir吸附，最大吸附量Γ_∞为1.4×10^-3mol／g，吸附常数k为5.5×10⁵（mol／L）^-1。研究结果表明亲脂性农药可与脂化后的纳米TiO₂形成稳定的复合体，对于进一步研制复合型可光降解的纳米农药具有重要的指导意义。 采用三种方案制备环境友好型纳米农药，并对其光催化降解率进行研究。研究表明硬脂酸能通过类似于酸和醇生成酯的反应与纳米TiO₂生成稳定的聚合物，将纳米TiO₂表面由亲水性变为亲油性。但硬脂酸改性的纳米TiO₂农药制剂的光催化降解率低于原位直接法制备的纳米TiO₂农药制剂，而在农药中直接加入纳米TiO₂制备的纳米TiO₂农药制剂的光催化活性最低。田间试验结果表明纳米TiO₂的引入不但不会降低农药的毒力反而能提高其生物毒力。更多还原

【Abstract】 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.更多还原