EFFECT OF CERTAIN ADMIXTURES ON COALESCENCE OF DROPS IN THE EXTRACTION SYSTEM TBP-HNO3 (HCL)

An attempt is made to characterize quantitatively the effect of the TB P hydrolysis products (butanol and dibutyl hydrogen phosphate) and sil ica admixtures on the drop coalescence in the two-phase system TBP-HNO 3 (or HCl). Lifetimes of a great number of particular drops on the pla nar phase boundary were measured, and the lifetime distribution was an alyzed. This allowed determination of the coalescence constant and als o (using physicochemical properties of the two-phase systems) estimati on of depth of the continuous phase layer between the drop and the pla nar phase boundary at the instant of the drop appearance on the surfac e, at the point when the coalescence becomes possible as a result of m echanical and thermal fluctuations, and at the point when the coalesce nce is decelerated by virtue of certain reasons. The coalescence rate at practically the same physical parameters of the systems is determin ed to a great extent by the nature of compounds occurring on the inter face. The structural-mechanical barriers due to the occurrence of sili ca in the surface layer of the aqueous solution containing 3 M HNO3 an d 0.03 M SiO2 are estimated at the planar phase boundary, In this case , the interface region is sharply different in physical properties fro m the bulk of the phases.