Effect of di-butyl phosphate on the distribution behavior of uranyl ions in PUREX solvent

Abstract

ABSTRACT Di-butyl phosphoric acid (HDBP) is one of the major hydrolytic and radiolytic degradation product of tri-n-butyl phosphate (TBP) employed for the extraction of U(VI) and Pu (IV) from the spent nuclear fuel dissolver solution. The presence of HDBP in the solvent phase limits the recovery of actinides during stripping. In view of this, the extraction and stripping behavior of uranyl nitrate in 1.1 M TBP in n-dodecane (n-DD) was studied in presence of di-butyl phosphate (HDBP). The distribution ratio (D) of uranium (VI) in HDBP/n-DD was negligible and the D value increased gradually with an increase in HDBP content in the organic phase. An alternate method was developed for estimation of HDBP in TBP/n-DD system based on uranium metal retention in organic phase. Based on the results it was found that 1 M HDBP in 1.1 M TBP/n-DD retained about 0.63 M of uranium (VI) in the organic phase during stripping. The results were further validated using irradiated solvent. FT-IR spectroscopic investigation also revealed the retention of U(VI) in 1.1 M TBP/n-DD containing HDBP even after several stripping with 0.01 M HNO3.