Salt Effect Model for Aqueous Solubility of TBP in a 5 to 100% TBP/n-Dodecane-Nitric Acid-Water Biphasic System at 298.2 K

The solubilities of nonelectrolytes in aqueous electrolyte solutions have traditionally been modeled by using the Setschenow equation for salt effect. The aqueous solubility of tri-n-butyl phosphate (TBP) during operating conditions of the Purex process is an important parameter for safety considerations. Use of the Setschenow equation for aqueous solubility of TBP under limited conditions has been reported in the literature. However, there is no general model available to account for the presence of the diluent and for the case of multicomponent electrolyte solutions in which only some electrolytes are solvated and extracted by TBP. An extended salt effect model is proposed for predicting the aqueous solubility of TBP in a 5 to 100% TBP/n-dodecane-nitric acid-water biphasic system at 298.2 K. The literature data on TBP solubility were correlated to aqueous acid concentration, diluent concentration in the solvents, and an interaction parameter for electrolytic solutes (extracted or not extracted by TBP)