Humic acid(HA)is a common membrane fouling substance and precursor of disinfection by-products in water.Carbon nanotubes(CNTs),polydopamine(PDA)and graphene oxide(GO)were used to prepare the double-layer GO/PDA/CNT low-pressure membrane by vacuum filtration.The presence of PDA on the surface of GO membrane was confirmed by ATR-FTIR analysis,and the stability of the double-layer membrane was verified by ultrasonic fragmentation.The permeability of the GO/PDA/CNT membrane was 1 238 L/(m2·h·MPa),which was higher than that of the GO membrane with 279 L/(m2 ·h·MPa).The humic acid removal rate of GO/PDA/CNT membrane was 88.5％,higher than that of GO membrane(85.8％)and CNT membrane(38.9％).After filtration,the specific flux of GO membrane and CNT membrane decreased to 0.314 and 0.697,respectively.The specific flux of GO/PDA/CNT membrane decreased the least(0.753).Increasing the stirring rate improved the removal of HA and reduced membrane fouling.High stirring rate aggravated the membrane fouling.Under acidic condition the HA removal rate of GO/PDA/CNT membrane was the highest(94.5％)and the membrane fouling was the most serious.The preparation of GO/PDA/CNT double-layer membrane will improve membrane filtration efficiency and enhance the removal of humic substances,as well as reduce the generation of disinfection by-products.
因具有影响因素少、成膜可控性强、膜孔径分布窄等优点,热致相分离(TIPS)法已成为制备聚合物多孔膜的重要方法之一.本文从相图出发,总结了近年来TIPS法制备醋酸纤维素、聚砜、聚苯乙烯、聚甲基丙烯酸甲酯、聚乙烯醇缩丁醛和聚醚砜等非晶态聚合物多孔膜的研究成果,并重点分析了稀释剂、凝固浴种类、凝固浴温度以及收丝速率等重要热力学和动力学因素对相分离过程及制得的非晶态聚合物多孔膜结构和性能的影响.最后,对TIPS法制备非晶态聚合物多孔膜目前面临的挑战和发展方向进行了讨论和展望.
以低分子量聚氧化乙烯醛(PEO-CHO)为改性剂,通过缩醛化反应制备出新型聚氧化乙烯-聚乙烯醇(PEO-PVA)膜,研究了 PEO-CHO添加量对膜理化结构和CO2/N2分离性能的影响.结果表明,PEO-CHO的端醛基可与PVA分子链上的羟基发生缩醛化反应,形成交联和接枝共存结构,从而有效抑制PVA结晶,提高PVA膜的气体渗透系数;当PEO-CHO添加质量分数为90％时,PEO-PVA膜的结晶度仅为1.34％,CO2渗透系数达到15.7 Barrer.此外,PEO-CHO含有的醚氧重复单元可以提高膜的CO2亲和力,PEO-PVA膜的CO2/N2理想选择性保持在56.
介绍了热致相分离法和熔融拉伸法制备聚丙烯中空纤维膜的研究进展.首先重点归纳了热致相分离法中稀释剂、冷却速率、成核剂等因素和熔融-拉伸法中退火温度、熔融拉伸比等制膜工艺条件对聚丙烯中空纤维膜结构与性能的影响;然后对聚丙烯中空纤维膜在体外膜肺氧合、膜蒸馏、膜吸收、膜萃取等领域的应用进行介绍;最后对目前聚丙烯中空纤维膜在制备和应用领域所遇到的挑战及前景进行讨论和展望.
膜曝气生物膜反应器(MABR)膜的传氧性能对MABR工艺的设计具有重要意义,本文通过小试对MABR膜传氧速率的影响因素进行了研究.结果表明,在相同运行条件下MABR膜元件采用并联方式较串联方式更有利于提升MABR膜的传氧性能,平均膜传氧速率随着供气流量的提高先增大后趋于稳定,随着供气压力的升高略有增加,随着反应液温度升高变化不明显,随着测试液中溶解氧浓度的升高而降低;停止供气后,MABR仍具有一定的传氧能力.本研究采用膜组件并联方式连接,在供气压力2 kPa,供气气量100 mL/min条件下,平均膜传氧速率达到12.7 g O2/(m2·d).
