Javad Saien - Department of Applied Chemistry, Bu-Ali Sina University, Hamedan ۶۵۱۷۴, Iran
Sayed Ali Ojaghi - Department of Applied Chemistry, Bu-Ali Sina University, Hamedan ۶۵۱۷۴, Iran

The influence of aqueous phase pH on the rate of liquid-liquid extraction was investigated using a two impinging-jets contacting device with a high velocity of jet flows. The recommended chemical system of toluene–acetone-water was employed. Applying pH values from its natural value of 5.6 to the maximum of 8, a range in which most industrial waters are lain, for the jets colliding force within 70.3 - 214.6 mN, leads a reduction in extraction efficiency and overall volumetric mass transfer coefficient up to about 18.9% and 35.2% respectively. A significant high variation is observed when the aqueous phase pH exceeds the water neutral value toward alkali conditions. These variations can be attributed to the adsorption of hydroxyl ions and causing a lower tension at the interface of phases. A comparison between the results in this work and those for drop dispersion extraction indicates a high sensitivity in this method. On the other hand, increasing jets force improves the performance of the contacting device however, simultaneously; the retarding effect of adsorbed hydroxyl ions would be intensified.

Aqueous phase pH, impinging jets, liquid-liquid separation, mass transfer coefficient,extraction efficiency