【作者】 赵莎；

【导师】 柳丽芬；

【作者基本信息】 大连理工大学 ， 环境工程， 2010， 硕士

【摘要】 导电聚合物由于具有无毒无害、制备简便、高的导电性和环境稳定性等特点而受到广泛关注。但其自身也存在机械可加工性能差的缺点,所以近年来导电聚合物复合材料已成为研究热点,即在单体聚合的过程中将不同的阴离子基团掺杂进导电聚合物膜内,在保持其原有性能的基础上,得到具有掺杂阴离子特性的导电聚合物复合膜。蒽醌及其衍生物能极大地促进氧还原为过氧化氢(H2O2)的反应速率,然而,通常将其以自然吸附和共价键合修饰在电极表面,经长时间使用后容易脱落,造成修饰电极稳定性和电催化活性的降低。因此,如何提高蒽醌衍生物修饰电极的稳定性和保证修饰电极的电催化活性已成为当今研究的热点。此外,由于均相electro-Fenton水处理方法存在介质pH条件苛刻、大量的酸碱消耗、产生大量含铁污泥和铁催化剂络合失活、流失等主要缺点,限制了该技术的大规模实用化。因此,开发和构建非均相electro-Fenton体系并将其应用于污水处理领域,已成为环境电化学学科广泛关注的课题。本论文采用电化学原位聚合方法制备了蒽醌单磺酸(AQS)掺杂的导电聚吡咯(PPy)复合膜(AQS/PPy)。利用扫描电镜、傅里叶变换红外光谱技术详细研究了它们的结构、形貌及组成性能。结果表明,在吡咯(Py)单体电化学氧化聚合的过程中,AQS作为对阴离子可实现对导电PPy膜的掺杂,获得具有多孔结构的导电聚合物复合膜。在不同的pH溶液中,利用循环伏安法、计时安培/计时库仑技术考察了AQS/PPy复合膜的电化学性质。结果表明,在酸性水溶液中掺杂于PPy膜内的AQS只经历了一步两电子转移的还原过程。同时,导电聚合物复合膜具有优良的环境稳定性和电化学重现性。利用循环伏安法(CV)、计时安培/计时库仑、旋转圆盘电极(RDE)、旋转环盘电极(RRDE)、Tafel极化、电化学交流阻抗(EIS)等技术手段研究了AQS/PPy复合膜修饰光谱纯石墨(SPG)电极对溶解氧分子还原反应的电催化性能。结果表明,在酸性溶液介质中导电聚合物复合膜修饰电极均能高效地催化溶解氧的两电子还原反应生成过氧化氢(H2O2),掺杂于导电聚合膜内的蒽氢醌(H2AQS)对氧还原反应起主要的媒介电催化作用。在比H2AQS催化氧还原反应生成H2O2更负的电位区域内,导电PPy膜能进一步催化H2O2的两电子还原反应生成H2O。此外,本论文还以AQS/PPy复合膜修饰光谱纯石墨作为电解池的阴极,以γ-Al2O3载体负载铜氧化物(CuO)作为活化H2O2的催化剂,构建了非均相electro-Fenton-like氧化体系。采用恒电位运行方式分别从体系温度、催化剂投加量等方面考察了该体系对苋菜红偶氮染料氧化降解效果的影响。确定了体系运行的最优化条件。并对非均相催化剂的稳定性与再生性能进行了评价。更多还原

【Abstract】 Conducting polymers have been applied in many fields because of convenience of preparation, harmlessness, high conductivity and environmental stability. Recently, the conducting polymer composite materials have been paid much attention because of the poor mechanical properties of pure conductive polymers. On one hand, the conductive polymer composite materials hold their primary properties, and on the other hand their mechanical properties have been improved at a certain extent.Recently, the electrochemical reduction of oxygen has also been widely studied on anthraquinones and their various derivatives modified electrodes,, since the surface modification of electrodes with anthraquinones greatly increase the rate of oxygen reduction to hydrogen peroxide (H2O2). However, anthraquinones and their various derivatives which are grafted as spontaneously adsorbed or covalently bound monolayer on the electrode surface, tend to desorb from the surface during the long-term operation, leading to a loss of electrocatalytic ability and stability of the working electrodes. So, how to improve the stability and the electrocatalytic activity of the anthraquinones derivatives modified electrodes becomes a research hotspot. In addition, homogeneous electro-Fenton systems have some well-known drawbacks, e.g. a limited pH range, the production of iron-containing waste sludge which is difficult to dispose, and the catalyst deactivation by some iron complexing agents like phosphates anions, that is why the development of heterogenerous electro-Fenton systems that causes extensive attention in the subject of electrochemical, especially for wastewater treatment.In this work, the functionalized PPy film with anthraquinone-monosulphonate (AQS) incorporated as dopant was prepared by electrochemical anodic polymerization of pyrrole (Py) at a glassy carbon electrode from aqueous solution. The prepared AQS/PPy hybrid film was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopic (FTIR). The results showed that anion AQS can realize the doping in the process of Py monomer electrochemical oxidation polymerization, synthesizing the conductive polymer composite film with porous structure. The electrochemical behavior of AQS in PPy matrix was investigated in various pH solutions using cyclic voltammetry (CV) and chronoamperometry/chronocoulometry, a single two-electron reduction step was observed for the resulting composite film in donor’s media. AQS/PPy hybrid film exhibits good stability and electrochemical reproducibility.The electrocatalytic reduction of oxygen on the AQS/PPy composite film was also investigated in detail in various pH solutions using various electrochemical techniques such as CV, chronoamperometry/chronocoulometry, rotating disk electrode (RDE), rotating ring-disk electrode (RRDE), Tafel polarity and electrochemical impedance spectroscopy (EIS). It was found that the conductive polymer composite film exhibits obvious catalytic behavior on the electrochemical reduction of oxygen into hydrogen peroxide (H2O2). The doping AQS is an effective mediator for the reduction of oxygen and the H2AQS is responsible for the enhanced catalytic activity. The PPy film can further reduce H2O2 to H2O in the potential range more negative than the potential range where the two-electron reduction of oxygen proceeds efficiently on the AQS sites.In addition, heterogeneous electro-Fenton-like system has been constructed by the AQS/PPy composite membrane modified spectrum pure graphite and the catalyst CuO/γ-Al2O3. The azo dye decay were determined as a function of temperature, catalyst dosage. The system operation optimization conditions have been found. Further, the stability and regeneration of the heterogeneous catalysts were also investigated under the optimum reaction conditions.更多还原