【作者】 程子洪；

【导师】 高占先； 马伟；

【作者基本信息】 大连理工大学 ， 有机化学， 2013， 博士

【摘要】 煤是我国的基础能源,在发电过程中产生大量的粉煤灰废弃物；现代煤化工生产过程也产生大量有毒有害废水。资源化处理作为废物处理的有效策略,可降低废物排放带来的污染,同时回收其中的资源。本文针对煤化工生产中产生的焦油深加工有机废水,建立电化学氧化耦合产氢新体系,处理废水同时回收氢气,研究有机物降解耦合产氢机制,以期强化有机物处理能力并降低成本；另一方面,创新性地提出煤发电厂产生的高铝粉煤灰和生物质等固体废弃物的资源化利用新途径,即通过吸附过渡金属离子后直接制备复合催化剂强化焦油深加工废水电化学氧化处理,实现低成本“以废治废”的目的。本论文主要研究的内容和结果如下：首先,通过新体系中进行苯酚电化学氧化降解耦合产氢的实验结果表明,新体系中收集氢气浓度大于98%,且苯酚类有机物存在会增大产氢量；苯酚降解满足一级动力学方程。3V电压时,苯酚降解、COD去除、产氢量、动力学、有机物降解电流效率(ICECOD)、能量效率以及有机物转化产氧(YH2)都可以分为三个阶段；结合LC-MS和UV对三个阶段进行了深入探讨。每个阶段COD去除动力学都可以用一级动力学方程描述,动力学常数随着时间的增加而增大,分别为1.86,4.11和7.77×10-3h-1。阳极区ICECOD在前两阶段先从0.326缓慢升高到0.357再快速升高到0.471,到第三阶段急剧下降到0.018。阴极区YH2在第一阶段从2.629L H2/g COD增大至3.168LH2/g COD,随之在第二阶段降低到2.416LH2/gCOD。增大电解电压可以提高苯酚降解和COD的去除速率,同时增大产氢量和产氢速率,但ICECOD、YH2以及氢气能量效率都随之下降。另一方而,利用准格尔地区的高铝粉煤灰和北方的松木粉吸附净化含有过渡金属的废水。表征结果表明高铝粉煤灰(FA-A)的主要成分为SiO2和Al2O3(>50%),具有很高的化学和热稳定性；松木粉生物质(SD-C)的主要成分为C、N、O,利于过渡金属离子的吸附。利用FA-A和SD-C吸附过渡金属镍离子的研究结果表明,FA-A和改性后的SD-C对镍离子的吸附量受pH的影响较小；吸附量随初始浓度的升高而升高,随投加量的增大而降低；FA-A和SD-C对镍离子的吸附分别符合Langmuir和Langmuir-Freundlich等温模型和二级吸附动力学；吸附过程的初期是由外部传质和内部扩散控制。第三,利用吸附过渡金属离子后的FA-A和SD-C直接制备催化剂及其在电化学氧化中应用研究结果表明,FA-A具有化学稳定性和铝含最高特性可作为载体,SD-C作为致止孔剂可以制备复合催化剂并增大催化剂的比表面积；复合催化剂的加入将COD去除率从30%提高到近60%；高浓度苯酚电催化氧化降解耦合产氢过程中,复合催化剂的加入将降解时间从504h缩短至144h, COD去除率接近100%,产氢速率提高了近10倍；与未添加复合催化剂结果相比,增大电压和添加复合催化剂都可强化有机物的去除和产氢,但从电流效率和能耗上考虑,加入催化剂进行电催化氧化更合适；复合催化剂条件下,苯酚的降解机理主要是氧化/催化降解,同时还有一定的吸附/电吸附作用。因此可以看出,FA-A和SD-C废弃物吸附过渡金属离子后可以直接制备催化剂应用到有机物电化学氧化降解过程中,实现以废治废、固体废弃物资源化利用。最后,根据苯酚的降解历程,从能耗、效率和经济性角度确定利用电化学将有机物进行开环氧化,并与生化和深度处理组合处理焦油深加工废水；将复合催化剂电化学氧化处理应用到实际焦油深加工废水处理工艺中,作为预处理过程可以有效地降低废水中的有机物,出水COD浓度降低至1000mg/L,提高废水的可生化性,工艺最终出水回用到生产中,实现废水废弃物的资源化再利用；对电催化氧化工序的技术经济性进行了分析,并探讨了不同中间产物COD和化学潜能。更多还原

【Abstract】 Coal is the basic energy resource of our country. A large amount of fly ash is produced in coal to electricity process. In addition, lots of poisonous and harmful wastewaters were generated in coal chemical production processes. As an effective means to dispose the wastes, resourceful treatment could not only reduce the pollution mentioned above, but also recycle the resources contained in these wastes. Focused on the organic wastewater produced in tar deep processing at coal chemical industry, a novel electrochemical oxidation system was investigated to degrade the wastewater and produce hydrogen gas. On the other hand, fly ash and biomass were continuously used to prepare composite catalyst following with the adsorption of transition metal ions. The composite catalyst was applied to enhance the degradation of organics in tar deep processing wastewater electrochemical oxidation treatment. This new approach could be an effective exploration of fly ash and biomass utilization and achieve the purpose of "disposal of wastes by wastes". The achieved results show below:1. Results obtained from hydrogen gas production coupled with phenol degradation in the new system show that the concentration of collected hydrogen is greater than98%, the presence of phenol type organics could strengthen hydrogen production, and the first order kinetics equation could well describe the COD removal. Three stages were observed of phenol degradation, COD removal, hydrogen production, kinetic, Instantaneous Current Efficiency (ICECOD), Hydrogen Yield to COD (YH2). and energy efficiency during concentrated phenol electrochemical oxidation at3V applied voltage, and first order model could well describe each stage rather than the whole process, and the kinetics constant were1.86,4.11and7.77×10-3h-1, respectively. ICECOD of the anode reactions slowly rose from0.326to0.357and then rapidly increases to0.471in the first two stages, while sharply decreased to0.018in the third stage. YH2of the cathode reactions increased from2.629LH2/g COD to3.168L H2/g COD in the first stage, and then reduced to2.416L H2/g COD in the second stage. In addition, the removal rates of phenol degradation, COD removal and hydrogen gas production were improved by increasing the applied voltage, while the ICECOD, and hydrogen energy efficiency reduced compared with3V applied voltage.2. The characterization results of high aluminum fly ash (FA-A) show that FA-A is mainly composed of SiO2and Al2O3(>50%), which has higher chemical and thermal stability, and the C, N, O contained in straw dust (SD-C) are beneficial for transition metal ions adsorption. Results obtained from nickel ions adsorption by FA-A and SD-C show that the adsorption capacity increased with the rise of initial concentration, and decreased with adsorbent dosage, while the pH of the solution had little influence on nickel adsorption by FA-A and SD-C. The maximum adsorption capacity obtained from the Langmuir isotherm model is10.49mg/g and9.109mg/g, respectively. The adsorption process is a physical adsorption, which is controlled by external mass transfer and intra particle diffusion process.3. The research results obtained from the preparation of catalyst by FA-A and SD-C after transition metal ions adsorption and the application in electrochemical oxidation process show that FA-A could be the host due to its chemical stability and high aluminum content, and SD-C formed good pore structure of the composite catalyst surface. On the other hand, the COD removal increased from30%to nearly60%when composite catalyst added, which is higher than that of approximately50%with FA-A based catalyst. Compared with nickel and copper doped composite catalyst, iron doped composite catalyst had better removal efficiency of organics. Furthermore, the degradation time cut504h to144h, COD removal is approximately100%, and hydrogen production rate increased nearly10times in concentrated phenol electrochemical oxidation process with the application of the composite catalyst. The organics removal and hydrogen production could be strengthened by increasing the applied voltage and using the composite catalyst, but it could be more suitable with the composite catalyst considering the current efficiency and energy consumption. Besides, the mechanism of phenol electrochemical oxidation degradation is mainly oxidation/catalytic oxidation, while adsorption/electric-adsorption and electric flocculation occurred to the degree. Therefore, it is feasible that the direct preparation of composite catalyst by the FA-A and SD-C after the adsorption of transition metal ions and its application in organics electrochemical oxidation process.4. From the perspective of energy consumption, efficiency and economy and the degradation route of phenol, it is determined that organics were degraded to ring-open stage by catalytic electrochemical oxidation, and combined with biochemical and advanced processing in tar deep processing wastewater treatment. The catalytic electrochemical pretreatment could effectively reduce the organics and COD in the wastewater, and improve biodegradability of the wastewater. The final effluent could be reused. The cost and technical economy accounting were analized finally.更多还原