Encyclopedia of Membranes

2016 Edition
| Editors: Enrico Drioli, Lidietta Giorno

Liquid Entry Pressure (LEP or LEPW)

Reference work entry
DOI: https://doi.org/10.1007/978-3-662-44324-8_1295

In membrane distillation it is of paramount importance that liquid does not fill the membrane pores, in order to keep membrane efficiency to the highest possible value. To this end hydrophobic membranes are normally used. The hydrophobicity can be quantified through the so-called liquid entry pressure (LEP) parameter, defined as the pressure difference at which liquid penetrates into the membranes pores.

The pressure required to force water through the structure is inversely proportional to the opening size and dependent on the polymeric properties of the membrane. A theoretical expression, based on Young-Laplace equation, enables the estimation of LEP (see, e.g., El Bourawi et al. 2006):
$$ \Delta P=\frac{2\gamma cos\theta}{r} $$
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  1. El Bourawi S, Ding Z, Ma R, Khayet M (2006) A framework for better understanding membrane distillation separation processes. J Membr Sci 285:4–29CrossRefGoogle Scholar
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  3. Smolders K, Franken ACM (1989) Terminology for membrane distillation. Desalination 72:249–262CrossRefGoogle Scholar

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© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  1. 1.University of GenovaGenovaItaly