【作者】 张玮；

【导师】 刘淼；

【作者基本信息】 吉林大学 ， 环境科学， 2019， 硕士

【摘要】 苯酚是重要的化工原料,应用领域正在不断扩大。苯酚具有很高的生物毒性和致癌性,对含酚废水的处理方式在不断优化和开发。目前,电催化氧化技术以其操作简易、自动化可行、环境兼容性好的优点广泛应用。钛基二氧化铅电极适用范围广,发展前景较好。本文依据近年来国内外学者对电极制备方法的改进和掺杂改性研究,对钛基二氧化铅电极的改性制备及对苯酚的电化学氧化降解进行了探索研究,以期延长使用寿命和优化电极的催化性能。本文利用强酸对碳纳米管进行共价改性,通过涂覆法与萘酚修饰到钛基上,使用直流电电沉积,制备出具有β-PbO2活性涂层的改性电极。制备工艺分析结果表明,各组成层厚度质量控制较好,并确定涂覆5层聚酯膜的电极性能最佳。FTIR光谱分析表明,经过混酸处理后,羧基、羟基等含氧官能团有效地引入到碳纳米管管壁的表面。利用光学显微镜和扫描电子显微镜对改性前后的多壁碳纳米管和二氧化铅电极进行表面形貌分析。结果表明,改性电极表面致密平整,机械强度、反应面积增大。尺寸分布统计结果显示电极表层孔隙尺寸达到纳米级。电沉积结束时,改性电极电压为1.6 V,常规电极为2.4 V,电极的导电性能明显增强。加速电极寿命试验显示,改性电极寿命为73.1 h,是常规电极的1.98倍。通过电解-还原循环测试,重复使用20次电极性能无明显下降,表明电极拥有良好的稳定性和重复使用性。以自制的改性Ti/PbO₂电极为阳极,石墨板为阴极,对模拟苯酚废水进行降解研究。实验考察了电流强度、电解质浓度、pH、极板间距、电解时间、搅拌速率、温度等因素对改性电极电催化氧化苯酚去除效果的影响,并进行了动力学分析和能耗分析。结果显示改性电极的电化学降解效果较好,苯酚去除率达到99%以上。苯酚去除率随着电流强度、电解质浓度、反应时间、搅拌速率、温度这些因素值的升高而升高,在所考察的范围内,电流强度和时间其正效应起主导作用;pH和极板间距对苯酚的去除率影响显著,但均有一最佳值。动力学分析结果显示,苯酚的电化学降解过程在不同反应阶段反应级数不同,总体上符合准一级动力学,在此基础上讨论了苯酚间接氧化的两种路径,此外,费用分析结果表明电极具有较好的实际应用经济性。更多还原

【Abstract】 Phenol is an important raw material for chemical synthesis,which are finding there an advanced field of application.Phenol has high bio-toxicity and carcinogenicity,and the treatment of phenol wastewater is continuously optimized and developed.Electrocatalytic oxidation technology is widely used due to its advantages of simple operation,automation and environmental compatibility.Titanium-based lead dioxide（Ti/PbO₂）electrodes are widely used in various industrial production.This thesis is based on the research achievements of domestic and foreign scholars on the improvement of preparation methods and doping modification,dealing with the modification,preparation and application on electrochemical oxidation of Phenol to improve the service life and catalytic performanceIn this paper,carbon nanotubes were covalently modified with strong acid,modified by Nafion on titanium substrate by coating method,and direct current electrodeposition was used to modify electrode withβ-PbO₂ active coating.The preparation process analysis showed that the thickness quality of each component layer was well controlled,and it was determined that the performance of the electrode coated with 5 layers of polyester film was the best.FTIR spectroscopy analysis showed that oxygen-containing functional group such as carboxyl or hydroxyl groups were effectively introduced into the surface of the carbon nanotube tube walls after the mixed acid treatment.Surface morphology analysis of multi-walled carbon nanotubes and lead dioxide electrodes pre-and post modification were analyzed by OM,SEM.The results showed that The surface of the modified electrode is compact and smooth,with increased mechanical strength and reaction area.The statistical results of the size distribution showed that the surface pore size was nanometer.At the end of electrodeposition,the modified electrode voltage was 1.6 V,and the conventional electrode was 2.4 V.The conductivity of the electrode was significantly enhanced.Accelerated electrode life test showed that the life of the modified electrode was 73.1 h,which was 1.98 times that of the conventional electrode.Through the electro-reduction cycle test,there was no significant decrease in the performance of the electrode after repeated use for 20 times,indicating that the electrode has good stability and reusability.The self-made modified Ti/PbO₂ electrode was used as the anode and the graphite plate was used as the cathode to study the degradation of simulated phenol wastewater.In the experiment,the effects of current intensity,electrolyte concentration,pH,plate spacing,electrolysis time,stirring rate and temperature on the electrocatalytic oxidation of phenol by modified electrode were investigated.The kinetic analysis and energy consumption analysis were carried out.It was found that the electrochemical degradation of the modified electrode was better。The removal rate of phenol was over 99%.The phenol removal rate increases with the increase of current intensity,electrolyte concentration,reaction time,stirring rate and temperature.In the range investigated,the positive effect of current intensity and time plays a leading role;There was a significant effect of pH and the spacing plateon on the removal rate of phenol,but both have an optimum value.The results of kinetic analysis showed that the electrochemical degradation process of phenol was different in different reaction stages and generally followed the pseudo-first order kinetics.Two paths of indirect oxidation of phenol were discussed.In addition,the cost analysis results showed that the electrode has good practical economics.更多还原