【作者】 段建田；

【导师】 魏世强；

【作者基本信息】 西南大学 ， 环境工程， 2008， 硕士

【摘要】 随着润滑油的广泛使用和对环境的日益关注，人们越来越重视润滑油对环境的污染问题。光催化氧化技术是近年来兴起的一种污染治理技术，能将难降解有机污染物氧化、分解，在常温常压下反应，操作简易，能耗低，所使用的催化剂TiO₂无毒无害，稳定性高，成本低，可回收利用，这门技术已引起越来越多的科研工作者的关注。本文以锐钛型纳米TiO₂为光催化剂，用1000W高压汞灯为紫外光源光降解双季戊四醇庚酸六酯（di-PEHECA）、三甲醇丙烷庚酸三酯多元醇酯类润滑油。实验设计研究了不同纳米TiO₂量、H₂O₂浓度、光降解反应时间、pH值和有机溶剂对双季戊四醇庚酸六酯（di-PEHECA）、二甲醇丙烷庚酸三酯光降解效率的影响，并研究了各因数影响下，两类润滑油的光降解动力学规律。主要研究结果如下：双季戊四醇庚酸六酯（di-PEHECA）和三甲醇丙烷庚酸三酯光降解研究结果表明：用异辛烷作有机溶剂，双季戊四醇庚酸六酯、三甲醇丙烷庚酸三酯的紫外光谱峰形最好，可作为紫外分析测试的最佳溶剂。锐钛型纳米TiO₂对di-PEHECA和三甲醇丙烷庚酸三酯光催化降解效果显著。在di-PEHECA浓度为50．2mg·mL^-1、紫外光照时间为20min的反应条件下，对照的光降解率为36．1％，而纳米TiO₂用量为1．26g·L^-1时光降解率为93．07％，较对照提高了约61％。在三甲醇丙烷庚酸三酯浓度为51．3mg·mL^-1、紫外光照时间为20min反应条件下，对照的光降解率为48．9％，而当纳米TiO₂用量为1．24g·L^-1时，光降解率为95．8％，较对照提高约48％。酸度对两类润滑油的催化降解具有明显影响，作用大小和方向与体系pH值具有密切关系。在di-PEHECA浓度为50．2mg·mL^-1、紫外光照时间为20min，di-PEHECA在强酸性和中性条件下光降解效果好，其降解率为93．0％～98．0％；当pH值为3．5左右时，降解率为97．93％；pH值为7．0时，光降解率为96．67％。而在弱酸性和弱碱性条件下降解效果较差，降解率仅为85％～89％。在三甲醇丙烷庚酸三酯浓度为51．3mg·mL^-1、紫外光照时间为30min反应条件下，在酸性范围内光降解率较低，光降解率只有60%～70%。而在pH为7．5～8．0时，光降解效果最好，可以达到95．8％左右。因此，三甲醇丙烷庚酸三酯光降解最适宜的pH范围为中性至弱碱性。H₂O₂能促进di-PEHECA和三甲醇丙烷庚酸三酯光降解。加入一定浓度的H₂O₂两类润滑油的光降解率均高于对照。对于di-PEHECA，当H₂O₂浓度低于2mol·L^-1时，对di-PEHECA光降解效率有一定程度增加，而H₂O₂在2mol·L^-1～3mol·L^-1浓度范围则有一个突变，光降解率急剧上升，光降解的效率达到95．92％，和对照比较，其光降解率提高约23％。与对照相比，H₂O₂对三甲醇丙烷庚酸三酯光降解率影响幅度不大，当H₂O₂浓度为3mol·L^-1降解率为92．07％，达到最高，其光降解率提高约9％。试验浓度为51．3mg·mL^-1三甲醇丙烷庚酸三酯和di-PEHECA浓度为50．2mg·mL^-1随光降解时间的变化规律研究结果表明：三甲醇丙烷庚酸三酯和di-PEHECA均随光降解时间的增加，降解率不断增加。在前20min内，光降解效果显著，光降解率随时间几乎呈直线上升，光降解20min时di-PEHECA和三甲醇丙烷庚酸三酯光降解率分别是75．26％和91．97％。光降解20min后，光降解率随时间的延长而增加；对于di-PEHECA光降解率增加幅度较大，而对于三甲醇丙烷庚酸三酯的光降解率增加幅度不大。当光降解时间为50min时，di-PEHECA和三甲醇丙烷庚酸三酯的光降解率分别高达90％和99％。有机溶剂对di-PEHECA和三甲醇丙烷庚酸三酯光降解效果影响显著。对di-PEHECA，四种有机溶剂的光降解效果次序为：异辛烷>丙酮>无水乙醇>二氯甲烷；而对三甲醇丙烷庚酸三酯，五种有机溶剂的光降解效果次序为：醇水溶液>甲醇>异辛烷>二甲苯>丙酮。因而，di-PEHECA光降解的最佳溶剂为异辛烷，三甲醇丙烷庚酸三酯光降解的最佳溶剂为醇水溶液。纳米TiO₂量、pH值、H₂O₂浓度对双季戊四醇庚酸六酯（di-PEHECA）光降解动力学变化影响的实验结果表明：采用指数回归拟合得到不同纳米TiO₂用量的动力学方程，其决定系数R²大于0．96。不同纳米TiO₂量对di-PEHECA光降解动力学过程遵循一级反应动力学规律。双季戊四醇庚酸六酯（di-PEHECA）在酸性（pH=5．10）、中性（pH=7．02）和碱性（pH=9．02）条件下，光降解动力学符合一级反应动力学规律，拟合决定系数R²大于0．975。pH对di-PEHECA的光降解动力学有明显的影响。双季戊四醇庚酸六酯在中性条件下的光降解速度最快。不同H₂O₂浓度对di-PEHECA光降解动力学也有明显的影响，当H₂O₂浓度增加到1．96～2．6mol·L^-1时，其半衰期与对照相比，缩短了5～6倍。这表明H₂O₂能加速di-PEHECA光降解。纳米TiO₂量、pH值、H₂O₂浓度和不同的有机溶剂对三甲醇丙烷庚酸三酯光降解动力学影响的实验结果表明：不同纳米Ti_O2用量对三甲醇丙烷庚酸三酯光降解符合一级动力学反应。纳米TiO₂用量从0．76g·L^-1增加到2．99g·L^-1，半衰期由128．4min缩短到10．4min，半衰期缩短12．8倍。不同H₂O₂浓度对三甲醇丙烷庚酸三酯的光降解动力学有明显的影响。与对照相比，H₂O₂浓度在0．65～1．96mol·L^-1范围，对三甲醇丙烷庚酸三酯的光降解有促进作用，速率常数均大于对照，半衰期比对照短。在酸性（pH=5．02）条件下，三甲醇丙烷庚酸三酯的光降解速率常数小，在中性（pH=7．06）和碱性（pH＝9．02）条件下，三甲醇丙烷庚酸三酯的光降解速率常数较大，在中性和碱性条件下的半衰期比酸性缩短2倍。四种有机溶剂对三甲醇丙烷庚酸三酯光降解动力学影响明显程度次序：丙酮>异辛烷>无水乙醇>甲醇。这表明丙酮有机溶剂更有利于三甲醇丙烷庚酸三酯的光降解。更多还原

【Abstract】 With the widespread use of lubricants and society is paying daily attention to environment, people take more and more concern about the environmental pollution of the lubricating oil. Photocatalytic oxidation is a pollution control technology arising in recent years.it can oxidize and decompose the recalcitrant organic pollutants, reaction at normal temperatures and pressures, it’s easy to operate and low energy consumption. The TiO₂ catalyst is nontoxic and innoxious, it presents great stability and recoverable. more and more researchers given great attention of this technology.This paper is according to anatase nano TiO₂ as photocatalyst to photodegrade dipentaerythritol hexa-caproate and trimethylolpropane tri-heptylate under the UV source of 1000W high-pressure mercury lamp. Study on photocatalytic degradation of the different dosage of titanium dioxide, concentration of H₂O₂ and different reaction time,different PH, different organic solvents, and analysis of reaction kinetics. The research results as follows:The results show that: Using iso-octane as organic solvents, dipentaerythritol six heptanoic acid ester （di-PEHECA）, trimethylolpropane tri-heptylate has the best peak shape after Photolysis, as the best solvent of UV-analysis test. Compared with the comparison, the significant was effects of anatase nano TiO₂ for dipentaerythritol hexa-caproate and trimethylolpropane tri-heptylate, With di-PEHECA concentration was 50.2 mg·mL^-1, ultraviolet radiation time was 20 min, when Nano TiO₂ dosage was 1.26g·L^-1 ,the degradation rate was 93.07%, the rate of photodegradation increase about 61%. and the trimethylolpropane tri-heptylate concentration was 51.3 mg·mL^-1.ultraviolet time was 20 min when the dosage of Nano TiO₂ was 1.24g·L^-1, photodegradation rate was 95.8%, the rate of photodegradation increase about 48%. The degradation of two types of lubricants catalytic has obvious implications for Acidity, It is closely related to pH.In di-PEHECA concentration of 50.2 mg·mL^-1 condition, ultraviolet radiation time was 20 min, The best effect of di-PEHECA in acid and neutral conditions, the degradation rate was 93.0%～98.0%; when the pH is 3.5, the degradation rate was 97.93%; when the pH is 7.0, the degradation rate was 96.67%. The drop of less effective was the conditions of weak acid and alkaline, the degradation rate was 85%～89%. When the trimethylolpropane tri-heptylate concentration was 51.3 mg·mL^-1 ultraviolet time was 20 min, The degradation rate was lower than acid conditions, the degradation rate was 60%～70%,when the pH is 7.5⁸.0, The best degradation is 95.8%, the most suitable pH of trimethylolpropane tri-heptylate is neutral and weak alkaline. H₂O₂ can promote photodegradation of di-PEHECA and trimethylolpropane tri-heptylate.Compared with the comparison,The rate was higher than the comparison of adding a certain concentration of H₂O₂ for di-PEHECA, When the concentration of H₂O₂ is less than 2 mo·L^-1, The efficiency of photodegradation increase to a certain extent, When the concentration of H₂O₂ is 2mol·L^-1～3 mol·L^-1, The efficiency of photodegradation sharp rise .reached 95.92%. Compared with the comparison, The rate of photodegradation increase about 23%, The degradation rate increased. less on H₂O₂ of trimethylolpropane tri-heptylate, When concentration of H₂O₂ is 3 mol·L^-1,the degradation rate was 92.07 %, the rate of photodegradation increase about 9%.When trimethylolpropane tri-heptylate concentration was 51.3mg·mL^-1, di-PEHECA concentration was 50.2 mg·mL^-1, With the light of the changes of time,the result show that: the rate of degradation increasing with the light of the increased time,Within the first 20 min, the effects of photodegradation is significant, With the rate of time-almost a straight line up,The time of 20 min, the degradation rate of di-PEHECA was 75.26%, the degradation rate of trimethylolpropane tri-heptylate was 91.97%. After 20 minutes of photodegradation, the rate of degradation increase in the extension of time, increasing greater extent of degradation rates for di-PEHECA,When the time of photodegradation is reaching 50 min, The photolysis rates were parting as high as 90% and 99% of di-PEHECA and trimethylolpropane tri-heptylate. The effect of degradation on organic solvents for di-PEHECA and trimethylolpropane tri-heptylate was sigmficantly.The photodegradation on the di-PEHECA order of four organic solvents is: isooctane>acetone>ethanol>dichloromethane, and photolysis results of the order of the trimethylolpropane tri-heptylate: alcohol solution>methanol>isooctane>xylene>acetone. Thus, the best photodegradation solvents of di-PEHECA is isooctane, the best photodegradation solvents of trimethylolpropane tri-heptylate is the alcohol solution.The dynamics of the experimental results of Nano-TiO₂ dosage, pH value, H₂O₂ concentration of di-PEHECA show that:Adopting exponential draft gained dynamic equation of different dosage of Nano-TiO₂,The decision coefficient,R²>0.96, The dosage of nanometer TiO₂ for di-PEHECA follow a one-order dynamics rules.lt is kept to one-order dynamics rules on Acid（pH=5.10） neutral（pH=7.02） alkaline（pH=9.02）. The decision coefficienti is more than 0.975. The photodegradation of the di-PEHECA has obvious influence for pH, The degradation was the best in neutral conditions. The photodegradation of the di-PEHECA has obvious influence for H₂O₂ concentration,When the H₂O₂ concentration add to 1.96～2.61mol·L^-1, Compared with the comparison,the half life shorten 5～6 times, This shows that H₂O₂ accelerates photodegradation of the di-PEHECA.The dynamics of the experimental results of Nano-TiO₂ dosagean, pH value,differt organic solvent and H₂O₂ concentration of the trimethylolpropane tri-heptylate show that: The dosage of nanometer TiO₂ for rimethylolpropane tri-heptylate follow a one-order dynamics rules,When the dosage of nanometer TiO₂ is from 0.76g·L^-1 add to 2.99g·L^-1,The half life is from 128.4min drop to 10.4min, The half life is shorten 12.8 times.The photodegradation of the trimethylolpropane tri-heptylate has obvious influence for H₂O-2 concentration. Compared with the comparison, the concentration H₂O₂ is in the range of 0.65～1.96mol·L^-1,It promoted photodegradation of trimethylolpropane tri-heptylate,The speed constant were greater than the comparison, The half life is lower the comparison.In the acid（pH=5.10） condition, The speed constant is lower, .In the neutral （pH=7.06） condition and alkaline（pH=9.02） condition, The speed constant is more. The half-life is abbreviater twice in the neutralcondition and alkalinecondition than in the acid condition/The order of influence of dynamics on trimethylolpropane tri-heptylate for four organic solvent was Acetone> isooctane> ethanol> methanol. This shows that the acetone more favorable photodegradation of trimethylolpropane tri-heptylate.更多还原