Radiation chemistry of the branched-chain monoamide di-2-ethylhexyl-isobutyramide

ABSTRACT

The radiolytic degradation of di-2-ethylhexyl-isobutyramide (DEHiBA) was examined by subjecting the compound to gamma irradiation, measuring the remaining concentration of the intact compound, identifying the degradation products, and measuring uranium distribution ratios. The combined effects of radiation dose, contact with aqueous solutions of HNO₃, and aeration were also examined. The DEHiBA displayed significant stability at doses up to 1000 kGy, undergoing a slow exponential concentration decrease that was accompanied by the appearance of multiple degradation products. The most abundant compounds that were formed by radiolysis resulted from cleavage of the C_carbonyl–N and C_ethylhexyl–N bonds, generating di-ethylhexylamine and mono-ethylhexyl-isobutyramide. Acid contact did alter the radiolytic pathways, with acid favoring cleavage of the C_carbonyl-N bond, while a more diverse array of compounds was formed in the absence of acid. Pulsed radiolysis experiments were also conducted, in which picosecond bursts of energetic electrons were used to irradiate solutions of dodecane containing DEHiBA; formation of the dodecane radical cation was implicated, which serially reacted with DEHiBA to form a radical or radical cation species intermediate in the formation of the observed products. The slow degradation kinetics suggests that DEHiBA possesses good potential for selective extraction of uranium in fuel cycle extraction operations.

KEYWORDS:

• Solvent extraction
• radiolysis
• monoamide
• degradation
• DEHiBA
• Uranium

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