碳纳米管改性PEBA膜的制备及氮气脱湿性能
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摘要
为提高膜法氮气脱湿性能,以聚砜(PSF)超滤膜为多孔支撑层,以聚醚嵌段酰胺(PEBA)为活性分离层,以羧基化碳纳米管(MWCNTs-COOH)为添加剂,以正丁醇为溶剂,通过涂覆法制备PEBA/MWCNTs-COOH混合基质膜,并研究碳纳米管含量对膜表面亲水性和氮气脱湿性能的影响,以及不同操作条件对膜分离性能的影响.结果表明:碳纳米管对PEBA的化学结构无影响,添加少量碳纳米管会稍微降低混合基质膜的结晶度,进一步增加碳纳米管含量会导致微晶产生;随着羧基化碳纳米管含量增加,膜表面亲水性增加,膜的渗透性和选择性均有显著提高,当MWCNTs-COOH质量分数为0.04%时,水蒸汽的渗透速率为246 GPU(1 GPU=3.35×10~(-9) mol/(cm~2·s·kPa)),H_2O/N_2分离因子为315,比无添加膜分别提高了107%和54%;随着渗透侧压力减小,H_2O/N_2分离因子增加,随着原料温度升高,H_2O/N_2分离因子下降.
In order to improve the nitrogen dehumidification performance of membrane,the mixed matrix membranes(MMMs) PEBA/MWCNTs-COOH were fabricated via coating method with polysulfone(PSF) ultrafiltration membrane as the porous supporting layer, poly(ether-block-amide)(PEBA) as the material of active layer, the carboxylic multi-walled carbon nanotubes(MWCNTs-COOH) as the filler, n-butyl alcohol as the solvent, the effects of MWCNTs-COOH concentration in a membrane on the hydrophilicity and nitrogen dehumidification property of the MMMs and the impacts of operating conditions on the permeation performance of the MMMs were explored. The results indicated that the addition of MWCNTs-COOH had no effect on the chemical structure of PEBA, a small amount of carbon nanotubes decreased the crystallinity of the mixed matrix membrane slightly,and further increasing the content of the carbon nanotubes caused the formation of microcrystal. It was found that with an increase in the content of carbon nanotubes, the hydrophilicity of the membrane increased, and both the permeance and separation factor of H_2O/N_2 were significantly improved. When the mass fraction of MWCNTs-COOH was 0.04%, the water permeance reached 246 GPU(1 GPU = 3.35 × 10~(-9) mol/(cm~2·s·kPa))and the separation factor of H_2O/N_2 was 315, compared with those of the pure PEBA membrane, which were increased by107% and 54%, respectively; as the permeate pressure decreased, the separation factor of H_2O/N_2 increased,and as the raw material temperature increased, the separation factor of H_2O/N_2 decreased.
In order to improve the nitrogen dehumidification performance of membrane,the mixed matrix membranes(MMMs) PEBA/MWCNTs-COOH were fabricated via coating method with polysulfone(PSF) ultrafiltration membrane as the porous supporting layer, poly(ether-block-amide)(PEBA) as the material of active layer, the carboxylic multi-walled carbon nanotubes(MWCNTs-COOH) as the filler, n-butyl alcohol as the solvent, the effects of MWCNTs-COOH concentration in a membrane on the hydrophilicity and nitrogen dehumidification property of the MMMs and the impacts of operating conditions on the permeation performance of the MMMs were explored. The results indicated that the addition of MWCNTs-COOH had no effect on the chemical structure of PEBA, a small amount of carbon nanotubes decreased the crystallinity of the mixed matrix membrane slightly,and further increasing the content of the carbon nanotubes caused the formation of microcrystal. It was found that with an increase in the content of carbon nanotubes, the hydrophilicity of the membrane increased, and both the permeance and separation factor of H_2O/N_2 were significantly improved. When the mass fraction of MWCNTs-COOH was 0.04%, the water permeance reached 246 GPU(1 GPU = 3.35 × 10~(-9) mol/(cm~2·s·kPa))and the separation factor of H_2O/N_2 was 315, compared with those of the pure PEBA membrane, which were increased by107% and 54%, respectively; as the permeate pressure decreased, the separation factor of H_2O/N_2 increased,and as the raw material temperature increased, the separation factor of H_2O/N_2 decreased.
引文
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[21]CAR A,STROPNIK C,YAVE W,et al.PEG modified poly(amide-b-ethylene oxide)membranes for CO2separation[J].Journal of Membrane Science,2008,307(1):88-95.
[22]CHOI J H,JEGAL J,KIM W N.Fabrication and characterization of multi-walled carbon nanotubes/polymer blend membranes[J].Journal of Membrane Science,2006,284(1):406-415.
[23]MAJEED S,FIERRO D,BUHR K,et al.Multi-walled carbon nanotubes(MWCNTs)mixed polyacrylonitrile(PAN)ultrafiltration membranes[J].Journal of Membrane Science,2012,403:101-109.
[24]SCHULT K A,PAUL D R.Water sorption and transport in a series of polysulfones[J].Journal of Polymer Science Part B:Polymer Physics,1996,34(16):2805-2817.
[25]邱实.基于碳纳米管的有机/无机杂化膜的制备及性能研究[D].杭州:浙江大学,2011.QIU S.Preparation and properties of organic/inorganic hybrid membranes based on carbon nanotubes[D].Hangzhou:Zhejiang University,2011(in Chinese).
[26]KIM S,PECHAR T W,MARAND E.Poly(imide siloxane)and carbon nanotube mixed matrix membranes for gas separation[J].Desalination,2006,192(1/2/3):330-339.
[27]DU J R,SHI X,FENG X,et al.Membrane gas dehydration in a pressure-electric coupled field[J].Journal of Membrane Science,2015,493:444-451.
[2]苗成朋.不对称静电场耦合膜法气体脱湿过程[D].天津:天津工业大学,2016.MIAO C P.Membrane gas dehydration in a asymmetric electrostatic coupled field[D].Tianjin:Tianjin Polytechnic University,2016(in Chinese).
[3]程庆来.聚乙烯醇-氧化硅杂化膜的制备及其丙烯脱湿性能的研究[D].天津:天津大学,2010.CHENG Q L.Preparation and propylene dehydration of polyvinyl alcohol-silica hybrid membrane[D].Tianjin:Tianjin University,2010(in Chinese).
[4]POTRECK J,NIJMEIJER K,KOSINSKI T,et al.Mixed water vapor/gas transport through the rubbery polymer PEBAX?1074[J].Journal of Membrane Science,2009,338(1):11-16.
[5]AZIZI N,MOHAMMADI T,BEHBAHANI R M.Comparison of permeability performance of PEBAX-1074/TiO2,PEBAX-1074/SiO2and PEBAX-1074/Al2O3nanocomposite membranes for CO2/CH4separation[J].Chemical Engineering Research and Design,2017,117:177-189.
[6]FENG S,REN J,LI Z,et al.Poly(amide-12-b-ethylene oxide)/glycerol triacetate blend membranes for CO2separation[J].International Journal of Greenhouse Gas Control,2013,19:41-48.
[7]WANG S,LIU Y,HUANG S,et al.Pebax-PEG-MWCNThybrid membranes with enhanced CO2capture properties[J].Journal of Membrane Science,2014,460:62-70.
[8]BHADRA M,ROY S,MITRA S.Flux enhancement in direct contact membrane distillation by implementing carbon nanotube immobilized PTFE membrane[J].Separation and Purification Technology,2016,161:136-143.
[9]LEE J,YE Y,WARD A J,et al.High flux and high selectivity carbon nanotube composite membranes for natural organic matter removal[J].Separation and Purification Technology,2016,163:109-119.
[10]史菁元.功能化碳纳米管/聚砜复合膜的制备与性能研究[D].天津:天津工业大学,2016.SHI J Y.Preparation and properties of functionalized carbon nanotubes/polysulfone composite membranes[D].Tianjin:Tianjin Polytechnic University,2016(in Chinese).
[11]SOLEYMANIPOUR S F,DEHAGHANI A H S,PIROUZFARV,et al.The morphology and gas separation performance of membranes comprising multiwalled carbon nanotubes/polysulfone Kapton[J].Journal of Applied Polymer Science,2016,133(34):(43839)1-8.
[12]El B N,RAMADAN A R,ESAWI A M K,et al.Novel carbon nanotube-cellulose acetate nanocomposite membranes for water filtration applications[J].Desalination,2014,344:79-85.
[13]GREKHOV A M,EREMIN Y S,BAKHTIN D,et al.Effect of agglomeration of carbon nanotubes on gas permeability of PVTMS/CNT mixed matrix membranes[J].Journal of Physics:Conference Series,2016,751:1-9.
[14]CONG H,ZHANG J,RADOSZ M,et al.Carbon nanotube composite membranes of brominated poly(2,6-diphenyl-1,4-phenylene oxide)for gas separation[J].Journal of Membrane Science,2007,294(1):178-185.
[15]AZIZI N,MOHAMMADI T,BEHBAHAMI R M.Synthesis of a PEBAX-1074/ZnO nanocomposite membrane with improved CO2separation performance[J].Journal of Energy Chemistry,2017,26(3):454-465.
[16]郭瑞乾,张萌,罗居杰,等.酸化多壁碳纳米管/含氟聚砜复合膜的制备及其对CO2/CH4分离性能研究[J].化工新型材料,2017,45(1):79-82.GUO R Q,ZHANG M,LUO J J,et al.Preparation of acidified multi-walled carbon nanotube/fluorine-containing polysulfone composite membrane and its separation performance for CO2/CH4[J].Chemical New Materials,2017,45(1):79-82(in Chinese).
[17]SRIDHAR S,AMINABHAVI T M,MAYOR S J,et al.Permeation of carbon dioxide and methane gases through novel silver-incorporated thin film composite pebax membranes[J].Industrial&Engineering Chemistry Research,2007,46(24):8144-8151.
[18]邱永涛,任吉中,赵丹,等.Pebax/[Bmim][PF6]共混膜的制备及性能研究[J].膜科学与技术,2016,36(5):9-15.QIU Y T,REN J Z,ZHAO D,et al.Preparation and properties of Pebax/[Bmim][PF6]blend membranes[J].Membrane Science and Technology,2016,36(5):9-15(in Chinese).
[19]BONDAR V I,FREEMAN B D,PINNAU I.Gas sorption and characterization of poly(ether-b-amide)segmented block copolymers[J].Journal of Polymer Science Part B:Polymer Physics,1999,37(17):2463-2475.
[20]ZHAO D,REN J,WANG Y,et al.High CO2separation performance of Pebax R/CNTs/GTA mixed matrix membranes[J].Journal of Membrane Science,2017,521:104-113.
[21]CAR A,STROPNIK C,YAVE W,et al.PEG modified poly(amide-b-ethylene oxide)membranes for CO2separation[J].Journal of Membrane Science,2008,307(1):88-95.
[22]CHOI J H,JEGAL J,KIM W N.Fabrication and characterization of multi-walled carbon nanotubes/polymer blend membranes[J].Journal of Membrane Science,2006,284(1):406-415.
[23]MAJEED S,FIERRO D,BUHR K,et al.Multi-walled carbon nanotubes(MWCNTs)mixed polyacrylonitrile(PAN)ultrafiltration membranes[J].Journal of Membrane Science,2012,403:101-109.
[24]SCHULT K A,PAUL D R.Water sorption and transport in a series of polysulfones[J].Journal of Polymer Science Part B:Polymer Physics,1996,34(16):2805-2817.
[25]邱实.基于碳纳米管的有机/无机杂化膜的制备及性能研究[D].杭州:浙江大学,2011.QIU S.Preparation and properties of organic/inorganic hybrid membranes based on carbon nanotubes[D].Hangzhou:Zhejiang University,2011(in Chinese).
[26]KIM S,PECHAR T W,MARAND E.Poly(imide siloxane)and carbon nanotube mixed matrix membranes for gas separation[J].Desalination,2006,192(1/2/3):330-339.
[27]DU J R,SHI X,FENG X,et al.Membrane gas dehydration in a pressure-electric coupled field[J].Journal of Membrane Science,2015,493:444-451.