Behavior of Water Permeation Through Liquid Surfactant Membrane on the Concentration Process of Metallic Ions

Abstract

In order to investigate the behavior of liquid surfactant membranes in a stirred tank, the membranes containing chelating reagents were used to concentrate copper(11). At the same time, the water permeation through the membranes, the breakdown of W/O emulsion drop and the entrainment of external aqueous solution into the emulsion were studied by using Ni (II) and Mn(II) as the tracers, which were not extracted by the chelating reagents. The following results were obtained:
(1) The efficiency of separation and the concentration of copper(II) ion were influenced by the water permeation through the membranes, the breakdown of the membranes and the entrainment of the external aqueous solution. However, it was found that the entrainment in the stirred tank was negligibly small.
( 2 ) The behavior of water permeation through the membranes was influenced by the species of chelating reagents used as the carrier. In the cases of benzoylacetone and (E)-2hydroxy-5-nonylbenzophenone oxime, water permeated through the membranes from the external aqueous phase into the internal phase, and the efficiency of the concentration of cupric ion was lowered. On the other hand, in the case of N-8-quinolyl-p-dodecylbenzenesulfonamide(henceforth DBSAQ), the direction of water permeation through the membranes changed during the experiment, that is, in the initial step, water permeated from the external to the internal phase, after that, water permeated from the internal into the external aqueous phase. This change was explained by the difference of permeation rate of hydrochloric acid through the membranes. Different from benzoylacetone and (E)-2-hydroxy-5-nonylbenzophenone oxime, DBSAQ reacts with hydrochloric acid to form the product which is soluble in the organic phase. As the results, DBSAQ plays the role of a carrier for hydrochloric acid.