MECHANISM OF EXTRACTANT LOSS IN SOLVENT-EXTRACTION PROCESS .1. TRANSFER OF SAPONIFIED D2EHPA FROM ORGANIC-PHASE TO AQUEOUS-PHASE AND ITS AGGREGATION BEHAVIOR

The phenomenon of the loss of saponified D2EHPA (di(2-ethylhexyl) phos phoric acid, HA) from organic phase to aqueous phase and its aggregati on behaviour were studied with FT-IR and DLS (dynamic light scattering ) techniques based on the fact that saponified extractant can form rev ersed micelles or w/o microemulsions in n-heptane, a non-polar diluent . The results indicate that ''normal micelles'' or o/w microemulsions are formed from acidic extractant and its sodium salt in aqueous phase , and the micelle or microemulsion drop has a non-polar core which on solubilize n-heptane, so the equilibrated aqueous phase containing ext ractant is a complex fluid rather than a ''real solution''. Therefore, the aqueous aggregate formation leads to the extractant loss in solve nt extraction process. Strong electrolytes can prevent or lessen the e xtractant loss. The results of this paper provide a theoretical possib ility for solving the problem of extractant and solvent loss in liquid -liquid extraction industry.