Kinetics of stripping of VO–D2EHPA complex from toluene phase by aqueous sulphate–acetate solution. Comparison of Lewis and Hahn cells

Abstract

The kinetics of stripping or backward extraction of VO 2+ from VOA 2 complex existing in di-2-ethylhexylphosphoric acid–toluene phase to the aqueous phase by acidic solutions containing 0.50 M sulphate and 0.25 M acetate has been measured by Lewis and Hahn cell techniques using the pseudo mass transfer coefficient ( q) and the flux ( F) methods, respectively. In the case of the Lewis cell technique, the stripping mass transfer coefficient ( k b) obtained from the ( q) method of data treatment has been converted to the ( k b) values obtainable from the ( F) method of data treatment, and this value has been justified experimentally. In addition, for the Hahn cell, the reverse conversion has been done and justified. The ( k b) value obtained from the Lewis cell measurements is about 50 times higher than the Hahn cell ( k b) value. The reason for this variation has been discussed. The low activation energy suggests that the diffusion of the species VOA + to the aqueous film of the interface is the rate controlling. For both cells, the ratio of ( k f) to ( k b) equals to ( K ex) of 10 −1.9 obtained from the distribution study.