Comparison of Cyclic Irradiation Behavior of Tri-Butyl Phosphate / Tri-Iso-Amyl Phosphate-Dodecane System in Nitric Acid Medium

ABSTRACT The degradation behavior of gamma irradiated solution of 1.1 M tri-butyl phosphate (TBP) in n-dodecane (n-DD) and 1.1 M tri-iso-amyl phosphate (TiAP) in n-DD loaded with nitric acid and uranium were compared up to 5 cycles upon recycling of the degraded solvent after 80 kGy in each cycle. The solvent was recycled by stripping the loaded metal with dilute nitric acid followed by alkali wash using sodium carbonate after each cycle. Subsequently, the physico-chemical properties and the metal extraction – retention properties of the recycled solvent were measured. The recycled solvent was analyzed using gas chromatographic and FT-IR spectroscopic analysis. Among the physico-chemical properties the interfacial tension of the recycled solvent decreased drastically after three cycles of irradiation, but the variation in the measured phase separation time was not significant. But, the concentration of the extractant (TBP/TiAP) decreased significantly upon recycling. Though the formation of nitro compounds was obvious from FT-IR analysis, the metal retention by recycled organic phases were comparable after each cycle of irradiation. HIGHLIGHTS Cyclic irradiation behavior of TiAP/n-DD and TBP/n-DD was compared under acid loaded and uranium loaded condition. The number of cycles, the solvent can be reused upon recycling was evaluated. Cyclic irradiation under uranium loading condition leads to degradation of the extractant (TBP/TiAP) to a significant extent as evident from GC-analysis. Accumulation of unwashable degraded products takes place upon recycling based on FT-IR analysis. GRAPHICAL ABSTRACT