【作者】 杨帆；

【导师】 邵路；

【作者基本信息】 哈尔滨工业大学 ， 化学工程与技术， 2021， 硕士

【摘要】 由于工业污染废水的排放和人口的持续增长,水资源污染和短缺的问题已引起世界各国的关注,近年来蓬勃发展的纳滤技术在处理废水和缓解全球水资源短缺方面发挥着关键作用,开发新型高性能复合纳滤膜、优化制膜方法、调节膜结构和性能以迎接“挑战”,已成为该领域重点关注的方向。本论文提出通过多酚仿生涂覆和异氰酸酯的界面交联耦合过程构筑耐酸型聚氨酯选择层复合纳滤膜的新方法,并系统地考察了复合膜的制备条件对分离性能和耐酸性能的影响规律并探讨了相关机理。以P84聚酰亚胺为基膜,采用多酚涂覆/异氰酸酯界面交联的方法构筑聚氨酯选择层复合纳滤膜。通过对合成制备过程的摸索、不同反应单体的选择、以及对不同反应条件的探究,优化了复合膜性能。利用0.2 g/L单宁酸的Tris溶液涂覆基膜1 h,采用溶剂交换的方法去除膜表面的水分,可减少副反应的发生,并减缓水分自然蒸发时拉普拉斯力对膜孔的破坏,随后将涂覆膜表面与浓度为0.5%（m/v）的甲苯二异氰酸酯交联1 min,优化条件下制备的纳滤复合膜对200ppm甲基蓝染料水溶液完全截留,渗透通量达到33.88 L h^-1 m^-2 bar^-1。通过傅里叶红外光谱（FTIR）、X射线光电子能谱（XPS）、扫描电子显微镜（SEM）、原子力显微镜（AFM）、水接触角等表征测试技术揭示了酚羟基与异氰酸酯基团通过亲核加成反应形成聚氨酯交联层的机理。由于复合纳滤膜稳定性和耐氯性能对其实际应用至关重要,因此本文进一步研究了聚氨酯选择层复合膜对不同染料的分离性能、耐酸碱稳定性、长期分离稳定性和耐氯性能。结果表明复合膜对不同染料均能保持较好的分离性能。结合强酸和强碱溶液处理后膜的分离性能和相关的FTIR、SEM、水接触角等表征结果得出结论,聚氨酯选择层复合膜由于氨基甲酸酯键中N原子的吸电子效应、单宁酸中大量苯环的共轭效应以及空间位阻具有优异的耐酸特性,能够在p H=1的硫酸溶液处理60 d后保持良好的分离效果,此外复合膜在连续50 h的分离过程中能维持稳定的性能。更多还原

【Abstract】 Due to the discharge of industrial wastewater and the continuous growth of sewage,the problem of water pollution and shortage has attracted the attention of countries all over the world.In recent years,the booming nanofiltration technology plays a key role in treating waste water and alleviating the global shortage of water resources.Therefore,the development of new high-performance composite nanofiltration membranes,optimization of membrane preparation methods,and adjustment of membrane structure and performance to meet the“challenge”have become the key to further research.In this paper,acid-resistant polyurethane selective layer composite nanofiltration membranes were constructed by biomimetic coating of polyphenols and interfacial cross-linking of isocyanate.The preparation conditions,separation performance and acid resistance of the composite membrane were systematically investigated.Polyurethane selective layer composite nanofiltration membrane was constructed by polyphenol coating/isocyanate interfacial cross-linking method on P84polyimide substrate.The performance of the composite membrane was optimized through the exploration of experimental methods,reaction monomers and reaction conditions.After coating the substrate with 0.2 g/L Tris solution of tannic acid for 1h,the remaining water on the membrane surface was removed by solvent exchange with n-hexane,which not only avoided the side reaction,but also mitigated the destruction of membrane pores due to the Laplace force when water evaporated naturally.Then,the optimized membrane prepared by cross-linking with 0.5%（m/v）isocyanate for 1 min,which performed completely rejection of 200 ppm MB solution and the permeation flux of 33.88 L h^-1 m^-2 bar^-1.In addition,we revealed the mechanism of preparing the composite nanofiltration membrane polyurethane selective layer by nucleophilic addition reaction between phenolic hydroxyl group and isocyanate group by FTIR,XPS,SEM,AFM,water contact angle and other characterization techniques.In addition to the separation performance,the stability and chlorine resistance of the composite membrane are also very important in practical application.Therefore,we explored the separation performance for different dyes,acid/alkali stability,long-term separation stability and chlorine resistance of polyurethane selective layer composite membrane to evaluate the practical application value.The results showed that the composite membrane performed universal separation effect for different dyes.Combined with the separation performance of the membrane after acid/base treatment and the relevant characterization results of FTIR,SEM and water contact angle,it is concluded that the polyurethane selective layer composite membrane has excellent acid resistance because of the electron absorption effect of N in carbamate bond,the conjugation effect and steric hindrance of a large number of benzene rings in tannic acid,and can maintain a good separation effect after being treated with sulfuric acid solution of p H=1 for 60 days.In addition,the composite membrane can maintain stable performance in the process of continuous separation for 50 h.更多还原