EXTRACTION OF NEPTUNIUM FROM TRIBUTYL-PHOSPHATE SOLUTIONS IN THE PRESENCE OF DIBUTYL HYDROGEN PHOSPHATE

The distribution of neptunium during its reextraction from an organic solution with composition 30% tributyl phosphate (TBP)-diluent (n-paraffin or CCl4) was studied. It was shown that regardless of the type of diluent the presence of dibutyl hydrogen phosphate (DBHP) in the organic phase leads to a decrease of the reextraction efficiency as a result of retention of neptunium in the organic phase in the form of a dibutyl phosphate complex. Saturation of the organic phase by uranium(greater-than-or-equal-to 5 g/liter) increases the efficiency of the reextraction process because of the competing ability of uranyl nitrate to form a dibutyl phosphate complex. The efficiency of a series of reextracting solutions for extraction of neptunium from an organic phase containing DBHP was verified. It was shown that alkali-metal peroxide and carbonate solutions are highly efficient.