Selective separation of n-butanol from aqueous solutions by pervaporation using silicone rubber-coated silicalite membranes

Authors

  • Toru Ikegami,

    Corresponding author
    1. National Institute of Advanced Industrial Science and Technology (AIST), Central 5-2, 1-1 Higashi 1, Tsukuba, Ibaraki 305-8565, Japan
    • National Institute of Advanced Industrial Science and Technology (AIST), Central 5-2, 1-1 Higashi 1, Tsukuba, Ibaraki 305-8565, Japan.
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  • Hideyuki Negishi,

    1. National Institute of Advanced Industrial Science and Technology (AIST), Central 5-2, 1-1 Higashi 1, Tsukuba, Ibaraki 305-8565, Japan
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  • Keiji Sakaki

    1. National Institute of Advanced Industrial Science and Technology (AIST), Central 5-2, 1-1 Higashi 1, Tsukuba, Ibaraki 305-8565, Japan
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Abstract

BACKGROUND: To use butanol as a liquid fuel and feedstock, it is necessary to establish processes for refining low-concentration butanol solutions. Pervaporation (PV) employing hydrophobic silicalite membranes for selective recovery of butanol is a promising approach. In this study, the adsorption behavior of components present in clostridia fermentation broths on membrane material (silicalite powder) was investigated. The potential of PV using silicone rubber-coated silicalite membranes for the selective separation of butanol from model acetone–butanol–ethanol (ABE) solutions was investigated.

RESULTS: The equilibrium adsorbed amounts of ABE per gram of silicalite from aqueous solutions of binary mixtures at 30 °C increased as follows: ethanol (95 mg) < acetone (100 mg) < n-butanol (120 mg). The amount of butanol adsorbed is decreased by the adsorption of acetone and butyric acid. In the separation of ternary butanol/water/acetone mixtures, the enrichment factor for acetone decreased, compared with that in binary acetone/water mixtures. In the separation of a model acetone–butanol–ethanol (ABE) fermentation broth containing butyric acid by PV using a silicone rubber-coated silicalite membrane, the permeate butanol concentration was comparable with that obtained in the separation of a model ABE broth without butyric acid. The total flux decreased with decreasing feed solution pH.

CONCLUSION: A silicone rubber-coated silicalite membrane exhibited highly selective PV performance in the separation of a model ABE solution. It is very important to demonstrate the effectiveness of PV in the separation of actual clostridia fermentation broths, and to identify the factors affecting PV performance. Copyright © 2011 Society of Chemical Industry

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