【作者】 卜龙利；

【导师】 全燮；

【作者基本信息】 大连理工大学 ， 环境工程， 2006， 博士

【摘要】 本论文采用一种新的工艺:微波辅助催化湿式氧化,在微波辐照和常压条件下,以活性炭或炭载金属为催化剂,空气为氧源,固定床反应器中动态连续地处理废水中的优先控制污染物对硝基酚（PNP）和五氯酚（PCP）;通过处理不同行业的实际高浓度有机废水来考察这种新工艺的实用可行性。 主要开展了以下几方面的工作: 首先为了消除活性炭或炭载金属催化剂吸附作用对目标物降解效果的影响,测定了PNP和PCP的吸附等温线,确定出实验过程中催化剂上目标物的预吸附量。 在活性炭固定床微波辅助催化湿式氧化实验中,考察了浓度从200～11000mg·L^-1的PNP溶液的处理情况,结果表明90%以上的PNP被降解;而且随着初始浓度的升高,反应出水浓度却保持不变,溶液中的PNP几乎被完全去除和矿化。通过考察微波功率、空气量、活性炭用量和进水流量等不同参数的影响作用得出反应最佳实验条件;最佳实验条件下长时间的连续运行发现,高温可使活性炭的微孔减少,从而使目标物的去除效率下降。邻硝基酚、苯酚、硝基苯、氢醌、苯醌和3-[对硝基酚基]-丙酸是PNP降解的主要中间产物,高温热解和氧化分解作用并存于PNP的降解过程中。电加热实验不能降解溶液中的PNP,炭化硅固定床对PNP的去除效果明显不如活性炭,活性炭的吸波性和吸附性在PNP的降解过程中起着重要作用。 应用微波能制备了炭载金属催化剂,表征发现,微波法制备的催化剂表面上金属颗粒分布均匀,其形貌尺寸和晶粒尺寸均小于传统浸渍法制备的金属颗粒形貌尺寸和晶粒尺寸。微波法制备炭载金属催化剂过程中不需要H₂还原,活性炭参与了金属的还原反应。 炭载金属催化剂微波辅助催化湿式氧化工艺可高效地降解和矿化溶液中的PNP和PCP。与活性炭相比,炭载金属催化剂表现出更高的去除效率和更好的实验稳定性。对PNP来说,金属的负载并没有改变PNP的降解反应历程,而只是加速了反应的进行;在PCP降解反应中,检测到脱氯和脱羟基的中间产物,高温热解和氧化反应同样并存更多还原

【Abstract】 A novel process, named microwave assisted catalytic wet air oxidation, is adopted for the treatment of p-nitrophenol （PNP） and pentachlorophenol （PCP） solutions through a granular activated carbon （GAC） or carbon-supported metal catalyst fixed bed under microwave irradiation and ambient pressure. The process is operated in continuous flow mode, and air is applied for oxygen supply. In order to investigate the possibility of its practical application, the process is applied to treat different industrial organic effluents with high concentration of pollutants.The following works are carried out in this dissertation:In order to eliminate the effect of GAC or carbon-supported metal catalysts adsorption on the degradation of target compound, the pre-adsorbed amounts of PNP and PCP onto catalysts are determined on the basis of their adsorption isotherms respectively.PNP solutions, its concentration from 200 mg·L^-1 to 11000 mg·L^-1, are treated by microwave assisted catalytic wet air oxidation using GAC as catalyst. The results show that PNP removal efficiencies are higher than 90%, and the concentration of the outflows keep constant with increasing initial solution concentration, PNP from aqueous solution are almost completely degraded and minerialized. Microwave power, air flow, GAC dose, and influent flow are proved to be major factors, and the influence of them on PNP degradation is investigated in order to obtain optimal experimental parameters. Under optimal conditions, the micropore amounts of GAC can be reduced for a long time irradiation, which result in the decrease of PNP degraded efficacy. o-Nitrophenol, phenol, nitrobenzene, hydroquinone, benzoquinone and 3-[p-nitrophenoxy] propionic acid are main course products for PNP degradation, pyrolysis and oxidation reaction coexist in the degradation pathways of PNP by microwave assisted catalytic wet air oxidation. PNP from aqueous solution can not be degraded in electrical heating experiment, and the removal effect of PNP treated by silicon carbide is apparently lower than GAC. The absorbing-microwave property and strong adsorption ability of GAC play important roles in the course of PNP degradation.Carbon-supported metal catalysts are prepared by using microwave energy, metallic particles disperse uniformly on the surface of GAC carrier, and its sizes of scanning electron microscopy and X-ray diffraction are smaller than those fabricated by conventional impregnation method. It needn’t hydrogen reduction in the process of catalyst preparation by microwave method, and GAC reacts to metallic oxide as reductant.PNP and PCP from aqueous solution can be degraded and mineralized effectively by microwave through a carbon-supported metal catalyst fixed bed. Compared with GAC, carbon-supported metal catalyst has a higher removal efficiency and better stability in the treatment of PNP solution. Metal loaded onto the catalyst don’t change the degradation pathways of PNP, and only accelerate PNP’s degradation reaction. Dechlorinated and dehydroxy course products are formed in the course of PCP degradation, pyrolysis and oxidation also coexist in PCP’s degrading course. Oxidation and sintered phenomena occur on the surface of copper and manganese particles, and the metallic leach happens in the course of reaction. Noble metal, such as platinum, has a good stability and no metallic dissolution in experiment.Biodegradability of the outflow, treated by GAC or carbon-supported metal catalyst, is improved apparently by microwave assisted catalytic wet air oxidation process.Pesticide wastewater, its initial CODo- concentration 7027 mg-L"1, and petrochemical aldehydic wastewater with initial CODo 33494 mg-L"1 are treated on the lab-scale setup by microwave assisted catalytic wet air oxidation. The results show that CODq- removal efficiency reachs 90% for pesticide wastewater, and CODa and TOC removal efficiencies are 94% and 99% for aldehydic wastewater respectively. Dye wastewater, pesticide wastewater, medical wastewater and simulating high concentration organic wastewater are treated on the pilot-scale apparatus, its design, manufacture and installation are completed by ourselves, and the high color removal and degrading efficiencies are obtained, and the biodegradabilities of real organic wastewaters are also improved.Based on energy balance calculation, microwave assisted catalytic wet air oxidation process adapts to treat high concentration organic wastewater. Increasing efficiencies of microwave energy utilization and heat exchanger can reduce the economical cost evidently, and increase the possibility of its practical application.更多还原