Studies in the extraction of tri-n-butyl phosphate from aqueous solutions

Abstract

30%TBP in dodecane is used for recovering plutonium and uranium from spent nuclear fuel in PUREX process. Mutual solubility of aqueous and the solvent phase will lead to a certain finite amount of TBP in the aqueous phase. This dissolved TBP at elevated temperatures can lead to exothermic reactions of explosive violence. Thus, removal of this dissolved TBP is important for safe disposal of the aqueous waste. The work done aims to study the removal of dissolved organic from aqueous nitric acid based solutions using solvent extraction technique on a batch and continuous manner. The analysis method for estimation of TBP present in both the phases has been developed. The concentration of TBP present in the organic phase has been newlinedetermined on GC while that in the aqueous phase has been determined on HPLC. newlineThe method development and validation has been done for direct assay of TBP present in nitric acid solutions by comparing the results obtained on GC and HPLC. Calibration of TBP in water upto 5ppm has been successfully done on HPLC. Kinetic study performed indicated that approximately 62 % of dissolved TBP was extracted from 0.3 M HNO3 as the feed using 3% TBP in NPH as the solvent with O/A ratio of 1:1 in only 5 mins at 35°C. The physical properties like density, viscosity, interfacial tension and solubility have been measured for TBP-nitric acid-dodecane system using pycnometer, viscometer, pendant drop method and High Performance Liquid Chromatography (HPLC) respectively. The equilibrium data has been successfully generated for TBP-NPH-nitric acid system for three different oncentrations of nitric acid ranging from (0.3-3M). The distribution ratio values of TBP have been found to be dependent on the concentration of TBP, nitric acid and NPH in the system.