ROTATING MEMBRANE CELL TECHNIQUE FOR THE STUDY OF LIQUID LIQUID EXTRACTION KINETICS/

The rotating membrane cell technique is described. The method has been tested on two types of systems: acetic acetic acid extracted by isopl opyl myristate, and Nickel and Zinc ions by di(2-ethylhexyl)phosphoric acid (D2EHPA). The technique consists of a membrane, containing one o f the phases, that is glued on the base of a cylinder and that is rota ted at a definite speed. The main features of the technique are: simpl icity of the set-up; good control of the transport in both phases; tra nsfer occurring in a transient regime, limited by the kinetics of the chemical reactions at the beginning of the transfer process. Moreover, the technique offers the possibility of stirring only one of the two phases. An approximate mathematical solution is given for the case of an interfacial transfer reaction. The results for acetic acid are in a ccordance with such a mechanism. In contrast, the results for the meta l cat;ions cannot be interpreted in the same way. The data may suggest the influence of a, transfer of D2EHPA to the aqueous bulk. The techn ique seems to constitute a simple tool for the identification of purel y interfacial reactions.