基于点击化学的聚丙烯腈膜功能化改性及性能研究

发布时间：2018-02-21 06:13

本文关键词： 聚丙烯腈点击化学烷基化反应超滤膜膜蒸馏　出处：《天津工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：聚丙烯腈(PAN)具有良好的耐溶剂性、化学稳定性和热稳定性,可以通过非溶剂诱导相转化方法进行加工成膜,且成膜性好,因此是一种常用的膜材料。但PAN膜的亲疏水适中,这使其在水处理的膜过滤和膜接触器中应用都存在较为严重的膜污染和膜浸润现象,从而限制了膜分离效率和膜的使用寿命。对PAN膜进行改性,以强化其亲水和疏水性能,使其能更好地满足不同形式的膜法水处理应用需求,是PAN膜需要重点突破的方向。点击化学方法操作简单、条件温和且转化率高,广泛应用于高分子合成及有机膜化学改性。针对水处理膜过滤过程中超滤膜通量低、抗污染性差的问题,本文通过点击化学实现环加成反应合成含1,2,3,4-四氮唑的亲水性聚丙烯腈共聚物(TZ-PAN),并以TZ-PAN与碘甲烷进行烷基化反应得到MTZ-PAN共聚物。通过控制反应时间(5min-120min)可以调控TZ-PAN和MTZ-PAN功能化程度(DF)为5%-16%。以相转化法制备TZ-PAN和MTZ-PAN平板膜,膜测试结果显示,随着1,2,3,4-四氮唑基团含量的增加TZ-PAN超滤膜接触角由63°降低到52°,水通量由111OL/(m2·h·bar)提高到715L/m2·h·bar),并对蛋白质溶液所造成的膜污染表现出更高的水利清洗可逆性,水通量恢复率为90%。烷基化处理后,超滤膜的机械性能极大增强,对于功能化程度为16%的MTZ-PAN膜,其断链伸长率增加至21%,但接触角升高到71°,水通量降低到242L/(m2·h·bar),BSA截留率仍保持在80%。通过点击化学和烷基化反应可以有效地调控PAN膜的亲水性,从而改善PAN超滤膜的纯水通量和抗污染性能。为进一步验证烷基链长度对PAN平板膜性能的影响,将癸烷和十六烷基分别通过烷基化反应引入到TZ-PAN共聚物中,DF为10%和20%。相转化制备TZ-PAN-癸烷和TZ-PAN-十六烷微孔膜在烷基链作用下具有较强的疏水性,且随着脂肪链长度和功能化程度的增加,制得的平板膜接触角逐步升高。当DF为20%时,TZ-PAN-癸烷膜的接触角为101°,TZ-PAN-十六烷膜的接触角为104°。将疏水改性PAN膜应用于直接接触膜蒸馏系统,对35g/LNaCl溶液进行脱盐处理,实验结果表明,随着料液温度的增加(50-80℃)TZ-PAN-十六烷疏水膜的膜蒸馏通量由3kg/(m2·h)提升至12kg/(m2·h),但分离因子仍小于1。相同功能化程度下,TZ-PAN-癸烷的膜蒸馏效果与TZ-PAN-十六烷相差不大。通过引入烷基链(癸烷和十六烷)可以有效提高PAN平板膜的疏水性,从而改善PAN膜的膜蒸馏的运行效果。
[Abstract]:Polyacrylonitrile (pan) has good solvent resistance, chemical stability and thermal stability. It can be processed by non-solvent induced phase transformation method and has good film-forming property, so it is a commonly used membrane material, but the hydrophobic property of PAN membrane is moderate. As a result, the membrane fouling and membrane soaking in water treatment membrane filtration and membrane contactor are very serious, which limits the membrane separation efficiency and membrane service life. The PAN membrane is modified to enhance its hydrophilicity and hydrophobicity. It is a key breakthrough direction for PAN membrane to meet the application requirements of different forms of membrane water treatment. The click-chemical method is easy to operate, mild conditions and high conversion rate. It is widely used in polymer synthesis and organic membrane chemical modification. In the process of water treatment membrane filtration, the flux of ultrafiltration membrane is low and the resistance to pollution is poor. In this paper, the hydrophilic polyacrylonitrile copolymers (TZ-PANN) containing 1o 2N 3N 4- tetrazole were synthesized by click-chemical cycloaddition reaction. The MTZ-PAN copolymers were prepared by alkylation of TZ-PAN with methyl iodide. By controlling the reaction time of 5 min-120 mins, the TZ-PAN and TZ-PAN copolymers could be controlled. The degree of MTZ-PAN functionalization was 5- 16.The TZ-PAN and MTZ-PAN flat films were prepared by phase inversion method. The results of membrane test showed that the contact angle of TZ-PAN ultrafiltration membrane decreased from 63 掳to 52 掳, and the water flux increased from 111 OLP / m 2 路h 路h 路barr to 715L / m 2 路h 路barg with the increase of the content of 1 ~ 2 ~ 2 ~ 3 ~ 3 ~ 3 ~ (-) -tetrazolium. The membrane fouling caused by protein solution showed a higher reversibility to water conservancy cleaning, and the water flux increased from 111OLR / m ~ 2 路h 路barp to 715L / m ~ 2 路h 路barge. The recovery rate of water flux is 90. After alkylation, the mechanical properties of ultrafiltration membrane are greatly enhanced. For MTZ-PAN membrane with functionalized degree of 16%, The elongation at break chain increased to 21, but the contact angle increased to 71 掳, and the water flux decreased to 242 L / m 2 路h 路h 路barbaron. The retention rate of BSA remained at 80%. The hydrophilicity of PAN membrane could be effectively regulated by click-chemical and alkylation reactions. In order to improve the pure water flux and antifouling performance of PAN ultrafiltration membrane, the effect of alkyl chain length on the performance of PAN flat membrane was further verified. Decane and cetyl were introduced into TZ-PAN copolymers by alkylation reaction. The phase conversion of TZ-PAN- decane and TZ-PAN- cetane microporous membranes had strong hydrophobicity under the action of alkyl chain. With the increase of the length of fat chain and the degree of functionalization, the contact angle of TZ-PAN- decane membrane increased gradually. When DF was 20, the contact angle of TZ-PAN- decane membrane was 101 掳and the contact angle of TZ-PAN- cetane membrane was 104 掳. Hydrophobic modified PAN membrane was applied to direct contact membrane distillation system. The desalination of 35g / L NaCl solution shows that, The membrane distillation flux of TZ-PAN- cetane hydrophobic membrane increased from 3 kg / m ~ 2 路h to 12 kg / m ~ 2 路h ~ (-1) with the increase of feed temperature, but the separation factor was still less than 1. The effect of membrane distillation of TZ-PAN- decane was similar to that of TZ-PAN- hexadecane at the same degree of functionalization. The effect of membrane distillation was similar to that of TZ-PAN- hexadecane by introducing TZ-PAN- hexadecane. Alkyl chain (decane and cetane) can effectively improve the hydrophobicity of PAN flat membrane. Thus, the operation effect of membrane distillation of PAN membrane was improved.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ051.893

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