光催化改性PVDF分离膜制膜设备设计及分离膜性能研究

发布时间：2018-03-03 21:06

本文选题：PVDF分离膜　切入点：平板刮膜机　出处：《华南理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：聚偏氟乙烯(PVDF)是半结晶性聚合物,具有良好的耐腐蚀性、化学稳定性和优异的成膜性能,广泛应用于膜分离技术领域,但PVDF分离膜易被滤液中有机物污染等缺点制约了它更多领域的应用。PVDF分离膜的性能和刮膜设备及铸膜液配方息息相关,因此通过改进制膜设备、完善铸膜液配方以及膜光催化改性来使PVDF分离膜性能更加优异具有重要的意义。本课题首先完成了实验室用平板刮膜机的设计,利用该设备制备出PVDF分离膜和Ti O2-PVDF杂化分离膜,并对优化出的杂化PVDF膜进行光催化改性。主要研究内容如下:首先,针对实验室用中小型平板刮膜机制膜精度不高和制膜效率较低的不足,通过精确调节旋钮来调节分离膜的厚度,同时采用凝胶水浴箱和导辊来辅助完成连续刮膜过程,进一步利用电机和在线测速调节装置来保证刮膜线速度的恒定,保证分离膜制品的精度。利用自行设计的刮膜机制备PVDF分离膜,探究了PVDF固含量和聚乙二醇-6000(PEG-6000)固含量对分离膜性能的影响;研究了不同Ti O2固含量对分离膜性能的影响,优化出Ti O2-PVDF杂化分离膜;自行制备了Ti O2溶胶,并对比了直接添加Ti O2、添加Ti O2/分散剂和添加Ti O2溶胶对分离膜性能的影响;最后对最优杂化膜进行光催化改性,探究了不同光照强度、不同光照时间、待滤液PH值和待滤液浓度对光催化改性分离膜自清洁性能的影响。研究结果表明:1)自行研制的科研用平板刮膜机膜厚可控精度高,膜厚可调节精度为1um,最大刮膜速度为2.0 m/min,凝胶水浴时间可控;2)当PVDF的固含量为22wt.%,PEG-6000固含量为12.5wt.%时,纯PVDF拥有较好的综合性能,其中纯水通量为1270L/(m2?h?bar),截留率为68%。3)当Ti O2固含量为0.5wt.%时,铸膜液成膜性能良好,改性分离膜较纯PVDF分离膜在热稳定性、亲水性等方面的均有一定程度的提升。通过制备Ti O2溶胶可以在一定程度上改善Ti O2在铸膜液中的分散性,添加溶胶态Ti O2的分离膜表面Ti元素重量百分比为4.66%,为三种改性分离膜里面最高。4)通过光催化紫外辐照实验,Ti O2光催化改性分离膜相较纯PVDF分离膜呈现出一定的自清洁特性。在1m W/cm2的紫外辐照下,16h时三种改性分离膜的通量恢复均比纯PVDF高19%以上;1m W/cm2的光照强度为此种Ti O2改性分离膜的最佳自清洁光照强度;待滤液PH=7时,Ti O2光催化改性分离膜的光催化改性效能最优;当腐殖酸浓度为0.5mg/L时,分离膜的通量衰减最小,自清洁效果最佳。
[Abstract]:Polyvinylidene fluoride PVDF (PVDF) is a semi-crystalline polymer with good corrosion resistance, chemical stability and excellent film-forming properties. It is widely used in membrane separation technology. However, the disadvantages of PVDF separation membrane being easily polluted by organic matter in filtrate restrict its application in many fields. The performance of membrane separation membrane is closely related to the scraping equipment and the formulation of cast membrane solution, so the membrane preparation equipment is improved. It is of great significance to improve the formulation of cast membrane liquid and the modification of membrane photocatalysis to improve the performance of PVDF separation membrane. Firstly, the design of lab flat scraping machine was completed, and the PVDF separation membrane and TIO _ 2-PVDF hybrid separation membrane were prepared by this equipment. The main research contents are as follows: first of all, aiming at the shortcomings of low precision and low efficiency of membrane preparation, the mechanism membrane of small and medium scale flat scraping used in laboratory is not high, and the photocatalytic modification of the optimized hybrid PVDF membrane is carried out. The thickness of the separation membrane is adjusted by adjusting the knob accurately, and the continuous scraping process is completed with the help of gel bath box and guide roll. Furthermore, the constant wiping speed is ensured by using the motor and the on-line speed adjusting device. The effect of solid content of PVDF and PEG-6000) on the performance of separation membrane was studied, and the effect of solid content of TIO _ 2 on the performance of membrane was studied. TIO _ 2-PVDF hybrid separation membrane was optimized, TIO _ 2 sol was prepared, and the effects of direct addition of TIO _ 2, TIO _ 2 / dispersant and TIO _ 2 sol on the performance of separation membrane were compared. The effects of different light intensity, different illumination time, PH value and concentration of filtrate on the self-cleaning performance of photocatalytic modified membrane were investigated. When the solid content of PVDF is 22 wt. and PEG-6000 solid content is 12.5 wt.%, the pure PVDF has better comprehensive properties, in which the pure water flux is 1270 L / m ~ 2? H? When the solid content of TIO _ 2 is 0.5 wt.%, the film formation performance of the cast liquid is good, and the thermal stability of the modified membrane is better than that of the pure PVDF separation membrane. The hydrophilicity of TIO _ 2 sol can be improved to some extent by the preparation of TIO _ 2 sol, and the dispersion of TIO _ 2 in casting solution can be improved to some extent. The weight percentage of Ti on the surface of the membrane was 4.66, which was the highest in the three kinds of modified membranes. The photocatalytic ultraviolet irradiation experiment showed that the phase of TIO _ 2 photocatalytic separation membrane was higher than that of pure PVDF membrane. The self-cleaning characteristics: the flux recovery of the three modified membranes under UV irradiation of 1m W / cm ~ 2 for 16 h is more than 19% m W / cm ~ 2 higher than that of pure PVDF, which is the best self-cleaning illumination intensity of the modified membranes. When the concentration of humic acid was 0.5 mg / L, the flux of separation membrane was the least, and the self-cleaning effect was the best.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.893

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