【作者】 温青；

【导师】 张宝宏；

【作者基本信息】 哈尔滨工程大学 ， 材料学， 2008， 博士

【摘要】 作为绿色工艺的电化学废水处理技术在有机废水的处理方面具有独特的优势,因而近年来备受国内外研究者的青睐。在电化学反应体系中,电极处于“心脏”地位,是实现电化学反应及提高电流效率,降低能耗的关键因素,因此,寻找和研制催化活性高的电极材料,具有很强的实际意义。PbO₂/Ti和气体扩散电极以其优异的电化学性能,在污水处理、电分析等领域的应用和研究日益广泛。本文中主要开展了新型Fe掺杂PbO₂/Ti阳极（Fe-PbO₂/Ti）和3种气体扩散电极的制备及其应用于污水处理的实验研究。采用电沉积法制备了Fe-PbO₂/Ti电极,并采用SEM、XRD、XPS对电极进行表征。以对硝基苯酚（p-NP）、十二烷基苯磺酸钠为去除目标,研究了Fe-PbO₂/Ti阳极电催化氧化难生化有机污染物的特性。结果表明,该电极对p-NP的降解效果>十二烷基苯磺酸钠。同时,考察了电流密度、有机物初始浓度、pH值对有机物去除率和降解动力学的影响,并建立了相关的电催化反应动力学模型,结果表明,有机物的去除符合表观一级反应动力学。采用循环伏安法、交流阻抗法、并结合高效液相色谱和气相色谱/质谱等分析手段对p-NP的降解机理、历程作了深入研究。结果表明,羟基自由基对有机污染物的降解起着重要作用,有机物的电催化反应属于电化学燃烧过程;p-NP的降解反应可能同时涉及扩散和吸附两种过程;p-NP在高于Fe-PbO₂/Ti电极析氧电位下,电催化氧化降解途径是直接氧化与间接氧化的共同作用;改性后的新型Fe-PbO₂/Ti阳极的抗污染能力较强,对p-NP的降解显示了良好的电催化活性和稳定性,p-NP电催化氧化反应速率常数比未掺杂PbO₂/Ti电极增加24%。以Fe-PbO₂/Ti为阳极,活性炭气体扩散电极为阴极,构建了新型电催化反应体系,研究了阴阳两极联合降解p-NP的效果,考察了电流密度、初始浓度、pH值、曝气量对p-NP去除率的影响。结果表明,在阳极电流密度24mA/cm²、曝气量20mL/s的条件下,处理浓度为100mg/L的p-NP废水,电解55min后去除率达100%,且双极氧化的槽电压可降低0.5V。该体系能耗低、效率高,对pH的适用范围广,有良好的环保应用前景。以自制的多壁碳纳米管（MWNT）气体扩散电极为阴极,石墨为阳极,构成电化学体系现场产生H₂O₂。采用星点设计-效应曲面优化法建立了各参数对于H₂O₂产生量的拟合模型。结果表明:MWNT气体扩散电极对催化氧还原产生H₂O₂的能力较强,在电流密度10mA/cm²、曝气量1.3L/min,60minH₂O₂产生量为707mg/L,是活性碳气体扩散电极H₂O₂产生量的2.2倍。实验还提出了一种以MWNT气体扩散电极为阴极,Fe板和Fe-Pb_O2/Ti电极为双阳极的新型电催化-电Fenton复合电化学污水处理体系,该体系具有很高的处理效率和较大的应用价值。实验构建了两种直接空气阴极单室生物燃料电池（ACMFC）进行同步废水处理和生物发电。ACMFC2具有内阻小、输出功率高,充放电性能及稳定性好等优点,其内阻为3.89Ω,最大输出功率密度774.8mW/m²。放电曲线、循环伏安测试表明,ACMFC2首次放电比容量和比能量分别为308mAh/gCOD和149mWh/gCOD。ACMFC2内阻组成分析表明,欧姆内阻为0.95Ω,非欧姆内阻在活化极化区和欧姆极化区占总内阻的比例分别为92.6%和75.58%。另外实验还以KMnO₄为阴极电子受体,构建了一种双室生物燃料电池,考察了KMnO₄浓度、pH值对MFC发电性能的影响。结果表明,KMnO₄浓度为500 mg/L时,MFC的最大开路电压可达1.68V,COD去除率为87.1%,库仑效率为45.2%。阴极液的pH值对电池的发电性能有显著影响,酸性溶液条件下有利于改善电池的性能。更多还原

【Abstract】 The electrochemical technology has attracted a great deal of attention recently, mainly because of its special advantage. The electrodes which are the heart in electrochemical reaction system are the important effect on increasing the removal rate of pollutions and reducing energy consumption. So the study of making electrodes with high electrocatalic ability has great practical significance.PbO₂/Ti and gas diffusion electrode are perspective materials due to their excellent electrochemical performances. Potential application such as wastewater treatment, electroanalysis, have been proposed and are being actively pursued now. The preparation of the novel Fe-doped PbO₂/Ti, three gas diffusion electrodes and their applications to wastewater treatment had been investigated.Fe doped PbO₂/Ti electrode was produced by electro-deposition and the electrode was studied by SEM, EDX, XRD. The characteristics of degradating organic pollutants were studied by electro-catalytic oxidation of Fe-PbO₂ /Ti, taking paranitrophenol and sodium dodecyl benzene sulfonate as model pollutants. The results show that the degradation efficiencies of paranitrophenol was bigger than sodium dodecyl benzene sulfonate’s. Various influence factors such as the initial concentration, current density and pH were examined. Furthermore, the degradation kinetic models were discussed. The results show that the first order reaction model can be used for the fitness of the organic pollutants removal.The electrochemical oxidation mechanism and degradation process of paranitrophenol on Fe-PbO₂/Ti electrode were studied in detail adopting the techniques of cyclic voltammetry, AC Impedance, combined with efficient liquid chromatographic technique and GC/MS. It was found that·OH was very important for degradating organic pollutant and electro-catalytic reaction of organic pollutant was electrochemical burning process. Above the oxygen evolution potential of Fe-PbO₂/Ti anode, the ways of paranitrophenol electrochemical oxidation included indirect electrochemical oxidation and direct electrochemical oxidation together. The results show that the novel Fe-PbO₂/Ti anode had perfect electro-catalytic activity and stability, and the electro-catalytic degraded rateconstant of p-NP increased 24%.The synergetic degradation of paranitrophenol in water by anodic/cathodic electro-catalysis was studied in a new electrocatalytic reaction system using gas diffusion electrode as cathode and Fe-PbO₂/Ti as anode. The influences of initial paranitrophenol concentration, current density, pH and aeration rate on the removal efficiency were investigateded. The degradation kinetics was discussed. The results show that when current density was 24mA/cm², aeration rate was 20mL/s, the removed rate of paranitrophenol with 100 mg/L concentration reached 100% after electrolesis of 55 min, and the cell voltage could decrease 0.5V. This system had low energy consumption, high efficiency and large application range for pH . This novel system had a great application priority.A system to produce H₂O₂ was built with graphite as anode and a gas diffusion electrode made in carbon nanotubes as cathode. The regression analysis was employed to set up a model for H₂O₂ production by the central composite designed experiment. When current density was 10mA/cm², 1.3 L/ min of air flow , the concentration of H₂O₂ could reach 707 mg/ L after an hour.A novel electro-catalysis and electro-Fenton electrochemical reaction system using carbon nanotubes gas diffusion electrode as cathode and Fe-PbO₂/Ti, Fe as double anodes was studied. This system had high efficiency and great potential for future environmental application.Two direct-air cathode single-chamber microbial fuel cells were constructed by using air electrode as cathode, foamed metal as anode and glucose as the anode fed. ACMFC2 had low internal resistance, high power density and nice discharge /charge ability. The internal resistance of ACMFC2 was 3.89Ω, the maximum power density could reach 774.8mW/m². The discharge curve and CV tests revealed that the first discharge capacity and energy was 308mAh/gCOD and 149mWh/gCOD. The ohmic resistance of ACMFC2 was 0.95Ω. When the ACMFC2 was in the activation overpotential area and the ohmic overpotential area, non-ohmic resistance accounted for 92.6% and 75.58% in the internal resistance. A new two-chamber microbial fuel cell was constructed by using potassium permanganate as cathodic electron acceptors.The influences of permanganate concentration and pH on the power generation performances of MFC were researched. The results show that the maximum open circuit voltage could reach 1.68V when permanganate concentration was 500mg/L and pH=2.0. Meanwhile, COD removal efficiency and coulombic efficiency were 87.1% and 45.2%. pH of catholyte was found to affect performance of MFC, which was meliorated when the catholyte is acidity.更多还原