【作者】 徐悦华；

【导师】 古国榜；

【作者基本信息】 华南理工大学 ， 环境工程， 2001， 博士

【摘要】 有机磷农药废水浓度高,毒性大,所含有毒物质抑制细菌繁殖,使生物处理效果受到影响,而光催化法能有效地将有机污染物降解为无机离子,无二次污染,为有机磷农药废水处理提供了一条新的、有潜力的途径。 甲胺磷在TiO₂表面预先吸附对甲胺磷光催化降解影响很大;根据实验结果,得出TiO₂吸附甲胺磷的Langmuir吸附等温方程C_e/q_e=0.1095 C_e+0.06347;红外光谱分析表明,甲胺磷在TiO₂表面吸附时通过磷酰基P=O中的氧与TiO₂中的钛形成配位键:根据实验结果,提出了光催化降解过程。 研究了甲胺磷光催化降解影响因素,TiO₂的最佳用量;酸性及碱性介质均有利于甲胺磷的降解:随着甲胺磷起始浓度的减小、光强的增大、通入空气量的增大,甲胺磷降解率均增大。加入少量的电子接受体H₂O₂或Fe³⁺均能大幅度地提高降解率。 推导出用有机物降解最终产物表示反应速率的公式;甲胺磷起始浓度在7.06～70.56mg.L^-1范围内时,其光催化降解为零级反应。用气质联用仪检测到CH₃-SO₂-SCH₃及CH₃S-SCH₃中间产物:用离子色谱法检测到SO₄^2-、NH₄⁺、NO₃^-,其中甲胺磷中的氮首先光催化生成NH₄⁺,再进一步氧化为NO₃^-,据此,提出了甲胺磷光催化降解的可能途径。探讨了用太阳光作光源,太阳光光强为18.2W.m^-2时,反应速率常数为0.02132mg.L^-1.min^-1。光催化降解甲胺磷和水胺硫磷结果表明,硫代磷酰胺类的甲胺磷较硫逐磷酸酯类的水胺硫磷容易降解。 TiO₂加入Fe（OH）₃胶体中制得复合Fe₂O₃/TiO₂,DRS研究表明TiO₂与Fe₂O₃复合以后,光的吸收性能提高了,且激发波长红移。XRD分析表明铁进入TiO₂晶格取代Ti,XPS分析也说明形成了Ti-O-Fe,故本研究提出TiO₂与Fe₂O₃复合的同时也进行了掺杂。光照Fe₂O₃/TiO₂时,光生电子从TiO₂表面向Fe₂O₃转移,同时晶格中缺陷作为电子的陷阱,使TiO₂表面电子—空穴对有效分离,从而提高了TiO₂的活性。存在Ti³⁺表面态使活性降低,Fe₂O₃/TiO₂光催化活性并不与表面羟基含量成正比。粒径及比表面积并不是影响Fe₂O₃/TiO₂活性的主要因素,光生电子—空穴对得到有效分离才是主要原因。更多还原

【Abstract】 The organophosphorous pesticides wastewater is thick and poisonous. The toxicants inhibit the reproduction of bacterium, so the pollutant degradation by microbe is poor. The organic pollutants can be effectively degraded into inorganic ions by photocatalysis, and there is no secondary’ pollution. The photocatalysis is a potential treatment for organophosphorous pesticides wastewater.The photocatalytic degradation of methamidophos is influenced greatly by the adsorption of methamidophos on the TiO₂ surface. The Langmuir adsorption isotherm equation of methamidophos on the TiO₂ surface C_e/q_e = 0.1095 C_e +0.06347 is put forward on the basis of the experimental results. A phosphoryl oxygen-titanium bond is formed via O of P=O with TiO₂ when methamidophos is adsorbed on the TiO₂ surface. According to the experimental results, the process of photocatalytic degradation is proposed.The influence factors on the photocatalytic degradation of methamidophos are investigated, such as the optimum amount of TiO₂. The degradation of methamidophos is more efficient in acidic medium and basic medium. The degradation efficiency of methamidophos increases with a decrease of the initial concentration of methamidophos or an increase of the light intensity and airflow. The degradation efficiency of methamidophos increases greatly when the electron acceptor H₂O₂ or Fe³⁺ is added.The kinetic equation, which is expressed by the products of organic pollutant degradation, is given. The photocatalytic degradation is a zero order reaction when the initial concentration of methamidophos is in the range of 7.06-70.56 mg.L^-1 . CH₃-SO₂-SCH₃ and CH₃S-SCH₃ are detected by GC-MS during the photocatalytic degradation of methamidophos. SO₄²- NH₄⁺ NO₃^- ion are determined by ion-chromatography. N in methamidophos is photocatalyzed into NH₄⁺ , and then NH₄⁺ is oxidized into NO₃^- . The proposed pathway of photocatalytic degradation of methamidophos is put forward on the basis of experimental results. The reaction rate constant of zero order of methamidophos is 0.02132 mg.L^-1 .min^-1 when the sunlight intensity is 18.2W.m^-2 . It is showed that the photocatalytic degradation of methamidophos is easier than that of isocarbophos by the experimental results.Fe2O3/ TiO2 is prepared by adding TiO2 in Fe（OH）3 colloid. DRS shows that the absorption property of light is improved and the red shift of excitation wavelength occurs after TiO2 is coupled with Fe2O3. According to XRD results, iron enters the TiO2 lattice;The Ti-O-Fe is confirmed by XPS, so ion doping is existing when TiO2 is coupled with Fe2O3. When the light illuminates Fe2O3/ TiO2, the electron moves from TiO2 to Fe2O3. At the same time, the defect in the crystal lattice acts as the trap, so the electron-hole pair on the TiO2 surface is separated effectively and the activity of Fe2O3/ TiO2 increases. Ti3+ surface state decreases the activity of Fe2O3/ TiO2, and the photocatalytic activity of Fe2O3/ TiO2 isn’t proportional to the amount of surface hydroxyl radical. The particle size and specific surface area aren’t the main influence factors on the activity of Fe2O3/ TiO2, and the effective separation of electron-hole pair is the main reason.Nano-sized TiO2 with good dispersion, high purity and high activity in the aqueous solution is prepared by the improved hydrolysis. The optimum preparation conditions are investigated. The degradation efficiency of photocatalytic degradation of methamidophos for 1 h is 61.3% by prepared TiO2, and 35.9% by TiO2 made in Japan. The characterization of nano-sized TiO2 is studied using TEM, XRD, TG, DTA, BET, IR and XPS, indicating that the photocatalytic activity of the photocatalyst must be evaluated by crystallite patterns, crystallinity, crystal size, specific surface area, surface state and surface hydroxyl radical. The single parameter is not proportional to the photocatalytic activity. The main reasons influencing the photocatalytic activity are the crystallite patterns and crystallinity.更多还原