Ultrafiltration by a compacted clay membrane-II. Sodium ion exclusion at various ionic strengths

Geochimica et Cosmochimica Acta
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Abstract

Several recent laboratory studies and field investigations have indicated that shales and compacted clay minerals behave as semipermeable membranes. One of the properties of semipermeable membranes is to retard or prevent the passage of charged ionic species through the membrane pores while allowing relatively free movement of uncharged species. This phenomenon is termed salt filtering, reverse osmosis, or ultrafiltration.

This paper shows how one can proceed from the ion exchange capacity of clay minerals and, by means of Donnan membrane equilibrium concept and the Teorell-Meyer-Siever theory, develop a theory to explain why and to what extent ultrafiltration occurs when solutions of known concentration are forced to flow through a clay membrane. Reasonable agreement between theory and laboratory results were found. The concentration of the ultrafiltrate was always greater than predicted because of uncertainty in values of some parameters in the equations.

Ultrafiltration phenomena may be responsible for the formation of some subsurface brines and mineral deposits. The effect should also be taken into consideration in any proposal for subsurface waste emplacement in an environment containing large quantities of clay minerals.

Publication type Article
Publication Subtype Journal Article
Title Ultrafiltration by a compacted clay membrane-II. Sodium ion exclusion at various ionic strengths
Series title Geochimica et Cosmochimica Acta
DOI 10.1016/0016-7037(73)90106-3
Volume 37
Issue 10
Year Published 1973
Language English
Publisher Elsevier
Description 17 p.
First page 2311
Last page 2327
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