Gas separation membrane systems have received a lot of attention from both industry and academia. This is due to the fact that there is belief that membrane ...
Available online at www.sciencedirect.com
Procedia Engineering 44 (2012) 791 – 792
Euromembrane Conference 2012 [P1.051] Polysulfone and polyimide hollow fiber gas separation membrane preparation and module manufacturing M. Etxeberria*, P. Corengia, S. Miguel, J. Zúñiga, E. Fernández-Gesalaga, P. Jiménez Tecnalia, Spain Gas separation membrane systems have received a lot of attention from both industry and academia. This is due to the fact that there is belief that membrane separation processes may offer more capital and energy efficiency when compared to the conventional separation processes in some applications. Development of ultrathin-skinned asymmetric membranes from highly selective polymers has been a challenge in gas separation processes. Although thousand of polymers exhibit permselective properties for gas mixtures, only a few glassy polymers are useful in making asymmetric gas separation membranes, particularly, polysulfone (PSf), polyethersulfone (PESf), polyetherimide (PEI) and polyimide (PI) [1]. Hollow fiber membrane modules are the most used module configuration in gas separation industry because of their unique characteristics of self-support, high membrane packing density and high membrane surface to volume ratio [2]. This work presents the Tecnalia’s research results on preparing gas separation hollow fiber membranes by the use of phase inversion method. Polysulfone (Udel P-3500 LCD MB7) and polyimide (Extem Resin XH1015) hollow fiber membranes have been prepared by dry-wet spinning technique using a home made hollow fiber spinning apparatus. Optimum polymer concentration of spinning solution for fiber preparation was determined by solution viscosity measurements. Various concentrations of polymer and nmethylpyrrolidone polymer solutions have been prepared and viscosity of each solution was measured by a viscometer. Polymer concentration was chosen taking into account that dope solution for hollow fiber preparation should exhibit significant chain entanglement [3]. Once optimum dope polymer concentration was chosen, hollow fiber membranes have been prepared varying some relevant spinning parameters as the spin-stretch ratio, the air-gap, the ratio of dope flow rate to bore fluid flow rate and bore fluid composition. The influence of spinning parameters on obtained hollow fiber structure and morphology has been studied by Scanning Electron Microscopy (SEM).
Fpoliymer/Fdope = 2
Fpoliymer/Fdope = 1
Fpoliymer/Fdope = 0.5
Figure 1. SEM images of polyimide hollow fiber membranes obtained at different ratio of dope flow rate to bore fluid flow rate Obtained hollow fibers were assembled into a lab hollow fiber module with the aim of studying their permeation properties. Permeability of H2, O2, CO2, CH4 and N2, and ideal selectivity of different pair of gases are being determined by the measurement of gas fluxes through the 1877-7058 © 2012 Published by Elsevier Ltd. Open access under CC BY-NC-ND license. doi:10.1016/j.proeng.2012.08.573
792
M. Etxeberria et al. / Procedia Engineering 44 (2012) 791 – 792
membranes due to the existence of a differential pressure between feed and permeate side of the membrane. *
Gas permeability (Pi) and ideal selectivity (α i/j) will be calculated by the following equations. At steady state, the permeability coefficient of a pure gas i through a membrane of thickness l is defined as:
Pi Ni Ni D *i / j ( p1i flux p 2 iof) / component l 'pi / l i, p1i and p2i Pare high pressure stream and low where Ni is normalized j Pi
pressure stream partial pressures of the component i, respectively. Δpi is the difference between p1i and p2i, and l is the thickness of the membrane.
References [1] Dongliang Wang, W.K. Teo, K. Li, Preparation and characterization of high-flux polysulfone hollow fibre gas separation membranes, J. Membrane Sci., 204 (2002) 247-256. [2] Dongfei Li, Rong Wang, Tai-Shung Chung, Fabrication of lab-scale hollow fiber membrane modules with high packing density, Separation and Purification Technology 40 (2004) 15–30 [3] Norman N. Li, Anthony G. Fane, W.s. Winston Ho, Takeshi Matsuura, Advanced membrane technology and Applications, Wiley Keywords: polysulfone, polyimide, hollow fiber, membrane modules
