【作者】 朱云庆；

【导师】 全燮；

【作者基本信息】 大连理工大学 ， 环境工程， 2013， 博士

【摘要】 陶瓷膜分离技术在水处理过程中的应用得到了越来越多的重视,然而其功能单一、浓缩液二次污染以及膜污染等问题制约了陶瓷膜分离技术的广泛应用。催化臭氧氧化技术可以有效分解和矿化水体中的有机污染物,但其应用过程中却面临催化剂流失严重以及回收困难的问题。通过将臭氧催化剂负载于陶瓷膜上,制备臭氧催化膜,有望实现催化臭氧氧化和陶瓷膜分离的多功能作用,从而在提高污染物去除率、缓解浓缩液二次污染以及减轻膜污染的方面起到一定作用,同时解决催化臭氧氧化技术中催化剂流失和回收的问题。本论文将催化臭氧化技术与陶瓷膜分离技术进行耦合,开发了两种具有不同结构的催化陶瓷超滤膜,用于催化臭氧氧化-陶瓷膜分离耦合工艺,同时进行了相关的中试试验研究。主要研究内容如下：采用溶胶凝胶法制备了催化层、分离层一体的Ce-Ti复合催化超滤膜,通过调控Ce-Ti溶胶的配比、粘度以及涂覆次数实现Ce-Ti复合催化超滤膜的可控制备。对模拟微污染地表水的处理结果表明,Ce-Ti复合催化膜在有机物去除方面具有催化臭氧氧化和陶瓷膜分离的耦合协同效应,对于四环素和腐植酸浓度分别为5mg/L和10mg/L的模拟地表水,在臭氧剂量为2.5mg/L时,四环素和腐植酸的去除率分别可以达到80%和72%,比单独臭氧氧化过程和膜分离过程的简单加和分别提高了36%和17%,其主要机理在于Ce-Ti催化剂增强了反应过程中羟基自由基的产生,从而促进了水体中有机物的分解。采用真空浸渍法制备了介孔Ti-Mn催化剂修饰的多级孔结构催化膜。Ti-Mn催化层的孔结构、催化剂负载量以及比表面积分别通过造孔剂的添加量、溶胶粘度以及溶胶颗粒尺寸等因素进行调节。对多级孔结构催化膜的结构进行分析,结果表明多级孔结构催化陶瓷超滤膜的膜面孔结构是由Ti02纳米棒组装的骨架结构和Ti-Mn催化剂的二级介孔结构共同组成的,而且由于压力的驱动,Ti-Mn溶胶充分渗入了支撑层的内部孔道,从而使膜的支撑层也负载了Ti-Mn催化剂,提高了催化剂的负载量。对模拟染料废水的处理结果表明,以多级孔结构催化膜为分离单元的臭氧-膜耦合工艺对于废水的脱色和污染物去除均有良好的效果,在中性条件下,对于入水CODcr为195.3mg/L的模拟染料废水,其色度和CODcr的去除率分别达到100%和74.3%,同时在连续运行过程中,其通量比相同运行条件下未负载催化剂陶瓷膜的通量有明显提高,说明多级孔结构催化膜为分离单元的臭氧-膜耦合工艺具有一定的抗污染性能。通过对比分析可以看出在以多级孔结构催化膜为主体单元的臭氧-膜耦合工艺中,实现了催化臭氧氧化和陶瓷膜分离过程的有效耦合,在去除有机污染物、缓解膜污染等方面产生了良好的协同效果。同时,设计和制造了日处理量为50t的臭氧-膜耦合中试试验装置,并以Ce-Ti复合催化陶瓷超滤膜以及多孔Ti-Mn催化剂修饰的陶瓷微滤膜为主要单元,针对大连市凌水水库微污染地表水进行了的中试研究。结果表明,Ce-Ti复合催化膜与臭氧耦合工艺可以提高水体中UV254和CODMn的去除率,同时对于水体中的细菌有良好的杀灭效果,出水浊度也远低于饮用水标准；此外,膜面污染现象也有一定缓解,膜通量稳定,反洗效果良好。对于多孔Ti-Mn催化剂修饰的陶瓷微滤膜与臭氧耦合工艺,对比分析催化剂负载前后的实验结果,发现催化剂负载后,催化臭氧氧化作用明显增强,显著提高了水中UV254和CODMn的去除率,促进了有机污染物的分解,同时出水总菌数和浊度都得到了有效的控制；此外,运行过程的膜通量也有明显提高,并延长了膜的反洗间隔时间,起到了改善膜面污染的作用。综上所述,本研究中所制备的两种不同结构的催化陶瓷超滤膜具有良好的臭氧催化能力,应用于臭氧-膜耦合工艺不仅可以提高污染物的去除效率,同时起到消毒灭菌的效果,而且可以有效改善膜面污染,是具有良好应用前景的催化陶瓷膜产品。更多还原

【Abstract】 Ceramic membrane has attracted plenty of attention for application in watertreatment since its producing cost was greatly reduced in the past decades. But there were still many problems that hindered the further development and application of ceramic membranes, among which post-treatment of retentate and membrane fouling were the most important problems which were mainly ascribed to the incapability of membrane separation process in degradation of organic pollutants. Catalytic ozonation was effective in degradation and mineralization of organic pollutants, but the problems in catalyst running-off and recycling have hindered the wide application of this technology. However, the combination of catalytic ozonation with ceramic membrane separation probably resulted in synergetic effects on enhancing the removal of organic pollutants and reducing the membrane fouling, and simultaneously, avoiding the catalyst running-off.In this work, two kinds of catalytic ceramic membranes were developed and used as key devices in the combined membrane-ozone system. And the main results were as below:Ce-Ti composite ceramic membrane was fabricated with sol-gel method. In the preparation process, the membrane thickness was controlled by adjusting the viscosity of the Ce-Ti mixed sol. The obtained Ce-Ti composite membrane was a typical asymmetric structured membrane, and the Ce-Ti composite layer was not only a separation layer, but also a catalytic layer. Treatment of tetracycline contaminated surface water showed the combined membrane-ozone system with Ce-Ti composite membrane as a key device displayed synergetic effect in the removal of tetracycline and HA. In the continuous mold reaction, when the initial concentration of tetracycline and HA were5mg/L and10mg/L, and the ozone dose was2.5mg/L, the removal rate of tetracycline and HA were about80%and72%, respectively, which were36%and17%higher than the sum of removal rate in single ozonation and membrane separation. The catalytic ozonation process occurred on the surface of Ce-Ti catalytic layer was proved to be the most important reason. The generation of hydroxyl redicals by decomposition of ozone on the surface of Ce-Ti composite catalyst dramatically increased the decomposition of organic pollutants.For further improving the catalytic capability of ceramic membrane and increasing the catalyst loading capacity and effective surface area, hierarchical porous catalytic ceramic membrane (HPCM) was designed and fabricated. The membrane layer was composed by TiO2nanorods assembled macroorous bone structure and mesoporous Ti-Mn catalytic substructure. The membranes were prepared by vaccum dip-coating method with TiC>2nanorods assembled ceramic membrane as supports. The pore structure and catalyst loading capacity were controlled by the viscosity and the particale size of the sol. The results of treatment of Red-3BS contained simulated dye water showed that the usage of HPCM in the combined ozone-membrane system could significantly increase the color and CODcr removal. For the influent with CODcr of195.3mg/L, the removal of color and CODcr were100%and74.3%, respectively, and the permeate flux was higher than that of support membrane at the same condition. The ozonation and catalytic ozonation were found to be the most important reasons for the increase in membrane-fouling reduction and pollutants degradation. Besides, the specific structure of hierarchical porous catalytic membrane also played important role in the combined ozonation-membrane filtration system.On the basis of Ce-Ti composite ultrafiltration membrane and porous Ti-Mn catalyst modified microfiltration membrane, the pilot-scale experiments were designed and performed with micropolluted surface water in Lingshui resevior as a target. The results shown that with Ce-Ti composite ultrafiltration membrane, the membrane fouling was substantially reduced, and the removal of UV254and CODMn were also increased to about80%. For porous Ti-Mn catalyst modified microfiltration membrane in the combined ozonation-membrane filtration system, the membrane fouling was reduced and the back-washing time interval was increased from4h for support to8h for catalytic membrane. Besides, the removal of UV254and CODMn was also increased.In summary, the two types of ceramic membrane with catalytic ozonation capability developed in this work were effective in the process of combined ozone and membrane and resulted in enhancement of the removal rate of organic pollutants and reduction of membrane fouling. We foresee that the process integrated ultrafiltartion and catalytic ozonation using the as-prepared novel membranes with catalytic capability as a key device may open an innovative way for enhanced water purification.更多还原