Role of water molecules in sodium bis(2-ethylhexyl) phosphate reversed micelles in n-heptane

Abstract

Abstract Recently molecular modeling was employed on the metal-extracted aggregates that form during the liquid/liquid extraction of transition metals. During the extraction process, the aqueous phase pH is adjusted with sodium hydroxide. In additional to the formation of the transition metal-extractant reversed micelles, sodium-bis(2-ethylhexyl) phosphate (NaDEHP) reversed micelles can also form. According to the classical model of reversed micelles, water molecules act as promoters for the formation of reversed micelles. Water molecules act as “gluing” agents for micellization in apolar media. Here we report a unique finding about the role of water molecules in reversed micellar aggregates using molecular modeling. The molecular modeling of the reversed micellar system of NaDEHP in n-heptane clearly shows that water molecules can act as an “antimicellization” agent. Water molecules have no gluing effect on the formation of NaDEHP reversed micelles. In fact, large NaDEHP reversed micelles are formed in “dry” conditions.