Studies on the acidification of carbonate waste stream for separation of di-butyl phosphate and recovery of metal

The aqueous waste generated during the treatment of Purex lean organic phase with alkaline carbonate solution contains washable degradation products and actinides in the form of carbonate complex. Management of such aqueous waste demands quantitative removal of the main degradation product, dibutyl phosphate (HDBP) and actinides from aqueous solution. In this context, batch studies have been carried out on the separation of HDBP from aqueous solution using n-dodecane (n-DD). For this purpose, the extraction behaviour of HDBP in n-DD was studied after acidification of alkaline carbonate solution with nitric acid. The studies with simulated waste containing HDBP and U(VI) nitrate showed the loss of U(VI) as precipitate during acidification as the uranium-DBP was poorly soluble in aqueous phase. However, the loss of U(VI) decreased with increase of aqueous phase acidity showing that the adjusted acidity of the carbonate waste plays an important role in the recovery of actinides.