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) phosphoric acid, HA) from organic phase to aqueous phase and its aggregation behaviour were studied with FT-IR and DLS (dynamic light scattering) techniques based on the fact that saponified extractant can form reversed 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 extractant is a complex fluid rather than a ''real solution''. Therefore, the aqueous aggregate formation leads to the extractant loss in solvent extraction process. Strong electrolytes can prevent or lessen the extractant loss. The results of this paper provide a theoretical possibility for solving the problem of extractant and solvent loss in liquid-liquid extraction industry.Chemistry, MultidisciplinarySCI(E)4111281-12873