【作者】 刘昀强；

【导师】 傅星；

【作者基本信息】 天津大学 ， 仪器科学与技术， 2015， 博士

【摘要】 超滤作为典型的膜分离技术在环保、医疗、食品、生物和污水处理等领域具有重要的应用价值,超滤膜是其中的关键器件。超滤膜的表面形貌和抗污性是直接影响分离效率和使用寿命的两个重要指标。本文针对实际应用需求,结合扫描探针显微镜(SPM)技术,在真空和大气环境下对超滤膜的表面形貌和抗污性的表征机理和方法进行了系统研究,提出了解决现有表征技术存在问题的多种思路和方法。这对于超滤膜的研制、生产和加工具有重要的指导意义。论文的主要工作和创新点包括:1.研究和探索了超滤膜表征理论和方法,提出了基于超高真空扫描隧道显微镜的超滤膜表面形貌表征方法和基于大气环境下原子力显微镜的超滤膜抗污性表征方法,并就实验结果对影响抗污性的多种因素进行了对比和分析。2.研究了适用于超滤膜特性表征的超高真空扫描隧道显微镜系统,设计了新型隧道电流提取电路和反馈控制电路,提高了隧道电流的采样准确度,设计了测头部分、样品加持装置和弹簧─阻尼隔振系统的机械结构,编写了实时数据采集和图像处理软件,最终实现了超滤膜形貌信息的拾取。实验研究了超高真空环境下超滤膜表面形貌的表征方法。3.提出了修饰不同蛋白的AFM探针弹性系数的可溯源标定方法,测量了蛋白和超滤膜之间的黏附力。评价了污染物与超滤膜之间粘附力的影响。实验研究了适用于超滤膜抗污性表征的二维力曲线测量方法。4.建立了探针谐振频率的变化量与所受作用力之间的数学模型,提出了超声原子力显微镜(UAFM)同时测量表面形貌和作用力的表征方法。提出了静电力显微镜(EFM)同时测量超滤膜的表面形貌、弹性模量和表面静电场分布的表征方法。这些方法为更好地研究抗污性多种因素之间的关系,以及对超滤膜的制备和应用提供了有价值的参考。5.提出了AFM与STM相结合同时测量样品形貌、弹性模量和样品表面电子态分布的表征方法。将新型隧道电流提取电路与AFM系统相结合,利用AFM二次抬举扫描模式实现了AFM扫描状态下隧道电流的采集,实验研究了导电样品表面形貌和电子态分布之间的关系。更多还原

【Abstract】 Ultrafiltration separation,as a typical technology of membrane separation, has wide applications in fields such as environmental protection, medical treatment, food industry, wastewater treatment, et al. Ultrafiltration membrane is the key device in ultrafiltration separation techniques. The characterization technologies for surface topography and antifouling property of ultrafiltration membrane are key factors of the separation efficiency and the service life. Based on the practical application requirements, the paper researches the theory and method of characterization technologies for surface topography and antifouling property using the scanning probe microscopy(SPM) in vacuum and atmospheric environment. Some novel ideas and methods are proposed to solve the problems in the traditional characterization technologies of ultrafiltration membrane. The above methods have important guiding significance for the research and production of ultrafiltration membranes. The main contents and innovations of the thesis are listed as follows.1. The theory and method of the characterization technologies of ultrafiltration membrane were researched. Based on the ultra high vacuum scanning tunneling microscopy(UHV-STM), characterization method of ultrafiltration membrane surface topography was proposed. Based on the atomic force microscope in atmospheric environment, characterization method of ultrafiltration membrane antifouling property was proposed. According to the experimental results, the factors influencing antifouling property were analyzed and contrasted.2. A system of UHV-STM was developed. The tunneling current extraction circuit and feedback circuit were designed with better sampling precision and better accuracy of the scanning image of the surface topography. The mechanical parts of the measuring head, the sample holder and the spring-damping isolation system were set up. The software consisting of real-time data acquisition and image processing was developed. The UHV-STM was used to characterize the surface topography of the ultrafiltration membranes. The method using UHV-STM to characterize the surface topography of the ultrafiltration membranes was validated by the experiments.3. As the spring constant calibration of the AFM cantilever probe was implemented with a precision balance calibration system, the AFM force curve method was used to measure the adhesion force between the protein-immobilized tip and the ultrafiltration membrane. The comparison of adhesion force measured with different probes and membranes was used to estimate the effects of adhesion as one of various impact factors of membrane antifouling property. Consequently, force volume mode of a novel commercial AFM was also used to realize the 2D in-plane scanning of the adhesion force information in the ultrafiltration membrane antifouling characterization.4. The theoretical model between the change of resonant frequency of AFM tip and the interaction force was established. The method based on ultrasonic AFM(UAFM) measurement system was proposed to measure the interaction force and get the surface topography of the ultrafiltration membranes at the same time. The method based on Electric force microscopy(EFM) was proposed to measure the interaction force, measure the elastic modulus and get the surface topography of the ultrafiltration membranes at the same time. These methods were valuable reference for the relationship research between several factors of antifouling property, and for the development and application of the ultrafiltration membranes.5. The characterization method based on the combination of AFM and STM was proposed to measure the Electronic distribution, measure the elastic modulus and get the surface topography of the sample at the same time. External power source and tunneling current exaction circuits was applied between the probe and the sample for upgrading and renovation of EFM mode in AFM. The novel scanning mode combining AFM and STM was applicable for the simultaneous imaging of surface topography, elastic modulus and surface electron state distribution measurement of the sample.更多还原