Effect of structure of N,N dialkyl amides on the extraction of U(VI) and Th(IV): a thermodynamic study

The temperature effect on the extraction behaviour of U(VI) and Th(IV) from 3 M HNO3 employing 1 M solutions of N,N diallkyl amides with varying alkyl substituents on the C-alpha atom viz. di(2-ethylhexyl)acetamide (D2EHAA), di(2-ethylhexyl)propionamide (D2EHPRA), di(2-ethylhexyl)isobutyramide (D2EH IBA) and di(2-ethylhexyl)pivalamide (D2EHPVA) in n-dodecane has been invest igated. These studies indicate that the extraction reactions of U(VI) and T h(IV) are enthalpy stabilised while the entropy factor counteracts the extr action. An attempt has been made to correlate the thermodynamic parameters with the structure of the extractant molecules.