Description of the Extraction of Trivalent REE and TPE Nitrates with Tributyl Phosphate and Its Solutions in Paraffins in the Presence of Nitric Acid and Salting-out Agents Using a Unified Model

Abstract

The extraction of trivalent REE and TPE nitrates with tributyl phosphate and its solutions in paraffins at room temperature in the presence of HNO₃ is described mathematically using a unified model involving parallel occurrence of several equilibrium reactions, suggested previously for modeling the extraction equilibria with REE and TPE in neutral systems and with hexavalent actinide nitrates in acid systems. The previously suggested set of equations was supplemented by the equation of the formation of a complex acid in the organic phase via addition of the HNO³ molecule to the element trisolvate.