Pervaporation of water/ethanol mixtures through microporous silica membranes

Abstract Several microporous silica membranes prepared by sol–gel processing were studied for separation of water–ethanol mixtures by pervaporation (PV). The permeate flux and separation factor of the prepared silica membranes decreased gradually at the beginning of the pervaporation-based separation of the water–ethanol mixture (ethanol concentration: 94 wt%); after 6–10 h, the PV performance characteristics reached a steady state. The water flux of the silica membranes ranged from 0.3 to 0.8 kg/(m 2  h), while the separation factor ranged from 10 to 500. Repeated PV experiments revealed that water and ethanol flux were high during the initial stages of the experiments and then declined; this pattern was observed more clearly at higher temperatures. A possible explanation for this phenomenon is that gradual physical and physicochemical adsorption subsequently plugged the membrane pores and prevented permeation. The relationship between PV performance and temperature was examined in the context of the adsorption–diffusion model for determination of the appropriate PV temperature.

[1]  M. V. Leeuwen.  Derivation of Stockmayer potential parameters for polar fluids , 1994 .

[2]  J. E. Elshof,et al.  Separation mechanism in dehydration of water/organic binary liquids by pervaporation through microporous silica , 2005 .

[3]  J. Caro,et al.  MFI membranes of different Si/Al ratios for pervaporation and steam permeation ☆ , 2000 .

[4]  M. Menéndez,et al.  A semi-continuous method for the synthesis of NaA zeolite membranes on tubular supports , 2004 .

[5]  Xianshe Feng,et al.  Estimation of activation energy for permeation in pervaporation processes , 1996 .

[6]  H. Kita,et al.  Synthesis of a zeolite NaA membrane for pervaporation of water/organic liquid mixtures , 1995 .

[7]  Donald W Breck,et al.  Zeolite Molecular Sieves: Structure, Chemistry, and Use , 1974 .

[8]  J. Falconer,et al.  Fundamentals and applications of pervaporation through zeolite membranes , 2004 .

[9]  Midori Watanabe,et al.  Hydrogen recovery from a H2-H2O-HBr mixture utilizing silica-based membranes at elevated temperatures. 1. Preparation of H2O- and H2-selective membranes , 1998 .

[10]  H. Kita,et al.  Zeolite NaA Membrane: Preparation, Single-Gas Permeation, and Pervaporation and Vapor Permeation of Water/Organic Liquid Mixtures , 2001 .

[11]  Jianhua Yang,et al.  Porous Silica-Zirconia (50%) Membranes for Pervaporation of iso-Propyl Alcohol (IPA)/Water Mixtures , 2002 .

[12]  J. E. Elshof,et al.  Transport mechanisms of water and organic solvents through microporous silica in the pervaporation of binary liquids , 2003 .

[13]  I. Ortiz,et al.  Comparison of SiO2-ZrO2-50% and commercial SiO2 membranes on the pervaporative dehydration of organic solvents , 2006 .

[14]  Jtf Jos Keurentjes,et al.  Hollow fibre microporous silica membranes for gas separation and pervaporation: synthesis, performance and stability , 2005 .

[15]  T. Tsuru.  Nano/subnano-tuning of porous ceramic membranes for molecular separation , 2008 .

[16]  J. Falconer,et al.  Pervaporation of Water/THF Mixtures Using Zeolite Membranes , 2001 .

[17]  G. Fischer,et al.  Preparation of zeolite membranes on the inner surface of ceramic tubes and capillaries , 2003 .

[18]  Dibakar Bhattacharyya,et al.  Pervaporation of alcohol–water and dimethylformamide–water mixtures using hydrophilic zeolite NaA membranes: mechanisms and experimental results , 2000 .

[19]  H. Verweij,et al.  High-selectivity, high-flux silica membranes for gas separation , 1998, Science.

[20]  Jianhua Yang,et al.  Pervaporation characteristics of aqueous-organic solutions with microporous SiO2-ZrO2 membranes : Experimental study on separation mechanism , 2006 .

[21]  T. Tsuru,et al.  Characterization of Co‐Doped Silica for Improved Hydrothermal Stability and Application to Hydrogen Separation Membranes at High Temperatures , 2008 .

[22]  J. Degrève,et al.  Transport of pure components in pervaporation through a microporous silica membrane. , 2005, The journal of physical chemistry. B.

[23]  E. Kikuchi,et al.  Preparation of mordenite membranes on α-alumina tubular supports for pervaporation of water–isopropyl alcohol mixtures , 2000 .

[24]  Michael Tsapatsis,et al.  Structure and aging characteristics of H2-permselective SiO2-Vycor membranes , 1994 .

[25]  M. Asaeda,et al.  Separation of inorganic/organic gas mixtures by porous silica membranes , 2001 .