摘要
抗污染膜的制备是解决膜污染问题的根本途径,是实现膜技术在其应用领域中长期、稳定运行的关键。本实验所进行的PVDF/PMMA/CA共混超滤膜的制备研究是在原有传统的相转化法的基础上引入化学反应,通过制膜液中的冰乙酸和凝胶浴中的碳酸钠反应生成二氧化碳气体的方法来达到调节膜孔径的均匀分布和提高膜的抗污染性能的目的。
本文首先采用L32(49)正交试验表,通过研究各因素对PVDF/CA共混微滤膜性能的影响程度,验证多元线性回归模型的可行性。其次以纯水通量、料液通量、截留率作为考察指标确定了影响PVDF/PMMA/CA共混超滤膜性能的主要因素,具体分为以下几步:(1)采用L18(2×37)正交试验表,通过极差分析法以及多元线性回归模型的分析,定量判断了各因素对膜性能的影响程度;(2)采用L27(310)正交试验表,考虑添加剂种类和添加剂含量的交互作用以及溶剂种类和添加剂种类的交互作用,通过正交试验完成实验数据的采集,并对其进行多元线性回归分析;(3)比较不同凝胶浴种类下制得膜的孔径分布和环境扫描电子显微镜照片;(4)使用研究级万能显微镜,分别观测最佳制膜液组成在不同凝胶浴种类下的成膜过程。
实验结果表明:(1)正交试验与多元线性回归模型相结合可以有效地优化制膜条件。(2)固含量、溶剂种类、添加剂种类、添加剂含量、凝胶浴种类是PVDF/PMMA/CA共混超滤膜性能的主要影响因子,其中固含量、添加剂种类是显著影响因子。以X1(固含量)、X2(溶剂种类)、X3(添加剂种类)、X4(添加剂含量)、X7(溶剂种类和添加剂种类的交互作用)五个影响因子为参变量,Y4(综合考虑纯水通量、料液通量和截留率三个指标)为因变量进行多元线性回归运算,得到回归方程:Y 4 = 4. 9211?1.8714X1?0.4618X2+0.7187X3?0.1527X4?0.2922X7。(3)最佳的超滤制膜液配方以及凝胶条件:固含量为16%、溶剂为DMF、添加剂PEG2000含量为2%、冰乙酸含量为10%、凝胶浴为碳酸钠水溶液、凝胶时间30分钟。在此优化条件下制备出孔径分布为0.07~0.10μm的PVDF/PMMA/CA共混超滤膜,其在0.1MPa室温条件下的纯水通量为197.26~265.24mL·cm-2·h-1,BSA料液通量为14.87~15.96mL·cm-2·h-1,对BSA的截留率为89.73~93.91%。(4)凝胶速度随时间的增长而下降。化学反应对凝胶速度影响较大,能显著增加膜的凝胶速度。
The preparation of high quality antifouling membrane is one of the most efficient methods to improvement antifouling characteristics of the membrane. PVDF/PMMA/CA blend UF membrane was prepared by chemical reaction way is based on the traditional phase-inversion method. The antifouling characteristics of the membrane is enhanced due to the uniformity of the membrane pore size, which is modulated by the carbon dioxide (CO2) gas, produced by a chemical reaction between glacial acetic acid (CH3COOH) in the casting solution and sodium carbonate (Na2CO3) as category of coagulation medium.
At first, an orthogonal table with nine factors and four levels L32 (49) was designed to confirm the feasibility of linear multi-regression model by study the influence degree of factors on characteristics of PVDF/CA blend microfiltration membrane. Secondly, the pure water flux, the feed solution flux of BSA and the observed retention of BSA had been used to estimate the characteristics of the PVDF/PMMA/CA blend UF membrane, the steps is as follows: (1) An orthogonal table with eight factors and three levels L18 (2×37) was designed and the influence degree of factors on characteristics of membrane had been determined by range analysis method and linear multi-regression model. (2) On this basis, the orthogonal table L27 (310) was designed to study both the interaction between additive content and additive species, additive species and solvent species. The linear multi-regression model was analyzed with the data collected by the orthogonal test. (3) The pore size distribution and SEM images of the membranes was compared, respectively. (4) By using optical microscope observed the process of membrane formation under optimum condition for preparing the PVDF/PMMA/CA blend UF membrane.
The results showed that: (1) The combination of orthogonal table and linear multi-regression model is an efficient method to ascertain the optimum preparation conditions for the porous membrane-making process; (2) Solid content, solvent species, additive species, additive content, category of coagulation medium are influencing factors on the characteristics of the PVDF/PMMA/CA blend UF membrane, and among which solid content and additive species are remarkable influencing factors; The relationship is as follows: , where, Y4 is a function that simultaneity consider the influence of the pure water flux, feed solution flux and observed retention, X1 is solid content, X2 is solvent species, X3 is additive species, X4 is additive content, X7 is the interaction between additive content and additive species; (3) When solid content of PVDF/PMMA/CA is 16%, using DMF as solvent, PEG2000 with 2% as additive, content of glacial acetic acid (CH3COOH) is 10%, category of coagulation medium is aqueous solution of sodium carbonate (Na2CO3), gelation time is 30 minutes; (4) The gelation rate decreased as the gelation time increasing. Chemical reaction affect gelation rate intensively, can increase gelation rate obviously.
Under this optimization condition of the membrane preparation, the PVDF/PMMA/CA blend UF membranes with uniform membrane pore size distribution and high pure water flux could be prepared, which pore size distribution is 0.07 ~ 0.10μm; the pure water flux is 197.26 ~ 265.24 mL·cm-2·h-1; the protein flux is 14.87 ~ 15.96 mL·cm-2·h-1 and the observed retention is 89.73 ~ 93.91%. The three parameters above are all measured under the 0.1MPa pressure at room temperature.
引文
1时均,袁权,高从堦等.膜技术手册.化学工业出版社, 1998:361~388
2王湛,周翀.膜分离技术基础.第二版.化学工业出版社, 2006:9~10
3刘茉娥等.膜分离技术.化学工业出版社, 1999
4汪锰,王湛,李政雄.膜材料及其制备.化学工业出版社, 2003:4
5王志,甄寒菲,王世昌.膜过程中防治膜污染强化渗透通量技术进展.膜科学与技术. 1999, 19(1):1~11
6俞三传,高从堦.浸入沉淀相转化法制膜.膜科学与技术. 2000, 20(5):36~41
7陆晓峰,楼福乐.超滤膜与超滤装置的研制和发展.核物理动态. 1994, 11(4):73~75
8刘忠州.膜分离技术在环境中的应用.膜分离技术在环境中的应用研讨会论文集.井冈山, 1977
9 A. S. Michaels. Membrane Process and Their Application: Needs, Unsolved Problems and Challenges in 1990’s. Desalination. 1990, 77:5~34
10吕亚文.聚偏氟乙烯超滤膜改性及其抗污染性能的研究.北京工业大学. 2001:1~17
11 M. D. Duca, C. L. Plosceanu, T. Pop. Surface Modifications of Polyvinylidene Fluoride (PVDF) under Rf Ar plasma. Polymer Degradation and Stability. 1998, 61(1):65~72
12武冠英,孙本惠,郭林等.聚氯乙烯超滤膜的溶剂蒸发速度影响研究.应用化学. 1988, 5(5):48~52
13刑丹敏,武冠英,胡家俊等.改性聚氯乙烯超滤膜的研究(Ⅰ).膜科学与技术. 1996, 16(1):49~55
14赵春田,礼巍,张贤等.聚丙烯微孔膜表面的空气等离子体处理.功能高分子学报. 1996, 9(3):337~344
15 J. A. Harris, J. C. Arthur. Radiation-Initiated Graft Copolymerization of Binary Monomer Mixtures Containing Acrylonitrile with Cotton Cellulose. Journal of Application Polymer Science. 1970, 14:3113~3123
16 B. D. Ratner, P. K. Weathersby, A. S. Hoffman. Radiation-Grafted Hydrogels for Biomaterial Application as Studied by the EACA Technique. Journal of Application Polymer Science. 1978, 22:643~664
17 M. Ulbricht, H. Matuschewski, A. Oechel, et al. Photo-Induced Graft Polymerization Surface Modification for the Preparation of Hydrophilic andLow-Protein-Adsorbing Ultrafiltration Membrane. Journal of Membrane Science. 1996, 115(1):31~47
18 V. Thom, K. Jankvoa, M. Ulbricht, et al. Synthesis of Photoreactiveα-4-Azidobenzoyl-ω-Methoxy-Poly(ethylene glycol)s and their En-on Photo-Grafting onto Polysulfone Ultrafiltration Membrane. Macromol. chem. Phys. 1998, 199:2723~2729
19陆晓峰,汪赓华,梁国明等.聚偏氟乙烯超滤膜的辐照接枝改性研究.膜科学与技术. 1998, 18(6):54~57
20 G. Capannelli, A. Bottino, V. Gekas, et al. Protein Fouling Behavior of Ultrafiltration Membranes Prepared with Varying Degrees of Hydrophilicity. Process Bichemistry. 1990, 25(6):221~224
21 Shoichet, S. R. Winn, S. Athavale, et al. Poly(ethylene oxide)-Grafted Thermoplastic Membranes for Use as Cellular Hybrid Bio-Artifical Organdy in the Central Nervous System. Biotechnology and Bioengineering. 1994,43:563~572
22邵平海,孙国庆.聚偏氟乙烯微滤膜亲水化处理.水处理技术. 1995, 21(1):26~29
23吕晓龙,赵卫光,胡成松等.聚偏氟乙烯中空纤维表面化学改性.天津纺织工学院学报. 1999, 18(4):8~11
24陆晓峰,陈仕意,李存珍.表面活性剂对超滤膜表面改性的研究.膜科学与技术. 1997, 17(4):36~41
25王国全,王秀芬.聚合物改性.中国轻工业出版社, 2000
26 N. Moussaif, R. Jerome. Modification of the Polycarbonate /Poly(vinylidene fluoride) Interface by Poly(methyl methacrylate) Effect on the Interfacial Adhesion and Iinterfacial Tension. Mzcromol. Symp.. 1999,139:125~135
27 N. Moussaif, R. Jerome. Compatibilization of Immiscible Polymer Blends (PV/PVDF) by the Addition of a Third Polymer(PMMA): Analysis of Phase Morphology and Mechanical Properties. Polymer. 1999, 40(14):3919~3932
28 S. T. Gashi, N. M. Daci, T. J. Selimi, et al. Preparation and Properties of Cellulose Acetate-Coal Heterogeneous Reverse Osmosis Membranes. Environ. Prot. Eng.. 2002, 26(4):29~37
29尹秀丽,邓桦,杨溥臣. PVDF/PS共混超滤膜的研究.水处理技术. 1997, 23(2):131~134
30程洪斌,尹秀丽.聚偏氟乙烯/聚丙烯腈共混膜的研究.天津纺织工学院学报. 1998, 17(1):54~60
31俞三传,高从堦.聚砜-聚醚砜共混膜相容性及凝胶特性研究.膜科学与技术. 1999, 19(5):23~26
32周金盛,陈观文. CA/CTA共混不对称纳滤膜分离特性的研究.膜科学与技术. 1999, 19(1):34~39
33于志辉,钱英,付丽等.聚偏氟乙烯/聚丙烯腈共混超滤膜的研究.膜科学与技术. 2000, 20(5):10~20
34郝继华,王世昌.聚合物-溶剂-非溶剂三元相图的计算.高等学校化学学报. 1995, 16(12):1831~1836
35钟银屏,赵长生,欧阳庆等.聚醚砜四元制膜液体系的相图计算.膜科学与技术. 1997, 17(1):63~68
36王连军,李恕广,江成璋. PES制膜体系亚层形成机理的研究.膜科学与技术. 2001, 21(1):4~9
37 S. Yang, Z. Z. Liu. Preparation and Characterization of Polyacrylonitrile Ultrafiltration Membranes. Journal of Membrane Science. 2003, 222(1-2):87~98
38 S. Yang, Z. Z. Liu, H. Z. Chen. A Gas–Liquid Cchemical Reaction Treatment and Phase Inversion Technique for Tormation of High Permeability PAN UF Membranes. Journal of Membrane Science. 2005, 246(1):7~12
39 S. M. Wang, Z. Wang, Y. Zhang, et al. Experimental Study of the Control of Pore Sizes of Porous Membranes Applying Chemicals Methods. Desalination. 2005,177(1):7~13
40 G. Capannelli, F. Vigo, S. Munari. Ultrafiltration Membranes: Characterization Methods. Journal of Membrane Science, 1983, 15(3): 289
41 M. Marcel. Basic Principles of Membrane Technology. Tsinghua University Press, 1999
42 A. J. Reyvers, C. A. Smolders. Formation of Membranes by Means of Immersion Precipitation: PartⅡ. The Mechanism of Formation of Membranes Prepared from the System Cellulose Acetate-Acetone-Water. Journal of Membrane Science. 1987, 34(1):67~86
43 H. J. Kim, R. K. Tyagi, A.E. Fouda, et al. The Kinetic Study for Asymmetric Membrane Formation Via Phase Inversion Process. Journal of Application Polymer Science. 1996, 62(4):621~629
44 H. Strathmann, K. Kock, P. Amor. The Formation Mmechanism of Asymmetric Membranes. Desalination, 1975,16:179~183
45吴金坤. PVDF的特性及其生产现状.化工新型材料. 1998, 26(12):10~13
46王庐岩.聚偏氟乙烯共混相容性及成膜机理研究.北京工业大学.2002, 5:11
47高以垣,叶凌碧.膜分离技术基础.科学出版社, 1989:2
48吴培熙,张留城.聚合物共混改性.中国轻工业出版社. 2000
49贠延滨,李继定,陈翠仙.聚乙二醇600和草酸对中空纤维超滤膜结构和性能的影响.水处理技术. 2006, 32(2):34~37
50贠延滨,李继定,陈翠仙. PVPK30和Tween80对中空纤维超滤膜结构和性能的影响.水处理技术. 2006, 32(1):14~17
51北京大学数学力学系数学专业概率统计组.正交设计.人民教育出版社,1976:101~147
52环国兰,张宇峰,杜启云,吴云.正交试验优化复合纳滤膜复合条件.膜科学与技术. 2004, 24(5): 77~79
53李振华,王金水,赵谋明,王玲玲,王艳.乙二醇对小麦面筋蛋白成膜特性的影响.食品工业科技. 2006, 27(4):152~155
54王一平,朱丽,张金利,胡彤宇,李韦华.仿生制备SiO2分离膜的实验.化学工程. 2005, 33(1):56~60
55苗所贵,王保国.“充填型”复合膜脱除水中微量有机氯化物的研究.高校化学工程学报. 2005, 19(3):297~302
56吴翠玲,李新平,秦胜利,王建勇. NMMO工艺纤维素膜成膜性能的研究.纤维素科学与技术. 2005, 13(3):29~34
57张阳,王湛,纪树兰,姚士仲,秦振平,彭跃莲.聚砜基膜成膜条件与富氧膜性能之间的关系.化学研究与应用. 2006, 18(6):653才658
58丁永建,叶柏生,刘时银.祁连山区流域径流影响因子分析.地理学报. 1999, 54(5):431~437
59 A. Bottino. The Formation of Micropoprous Polyvinylidene Difluoride Membrane by Phase Separation. Journal of Membrane Science. 1991, 57(1):1~3
60刘双进.污水处理新技术.海洋出版社, 1985
61沈飞,陆晓峰,卞晓锴,施柳青.聚乙烯醇缩丁醛超滤膜的制备.膜科学与技术. 2005,12(6):59~63
62 M. Wang, L. G. Wu, C. J. Gao. The Influence of Phase Inversion Process Modified by Chemical Reaction on Membrane Properties and Morphology. Journal of Membrane Science. 2006, 270(1-2):154~161
63 K. C. Ingham. Ultrafiltration Membrane and Application. Cooprt A R. New York: Plenum, 1980:141
64孙本惠.用相转化法制备非对称膜的凝胶动力学研究.水处理技术. 1993, 19(6):308~312