The extraction behaviour of nitric acid, uranium(VI), and plutonium (IV) has been investigated using N,N-dihexyloctanamide (DHOA) in n-dodecane. Results indicate that, similar to TBP, the amide extracts HNO" U(VI), and Pu(IV) as HNO,.DHOA, U02(NO,),.2DHOA and Pu(NO,),.2DHOA, respectively, from moderately acidic solutions (35 M HNO,). On the other hand at higher acidities (8.5 M HNO,), similar to tertiary amines, anionic species, U02(NO,),-and PU(NO,),Z-are extracted as [U0 2(NO,r,] [HDHOA+] and [Pu(NO,)l-] [HDHOA+]z, respectively, by ion-pair formation. The basicity of the amide (K H = 0.188), indicated by the equilibrium constant for the uptake of nitric acid is marginally larger than that of TBP (0.160). The third phase formation in H 20-HNO,-0.5 M DHOA-n-dodecane system occurs when nitric acid concentration in the aqueous phase approaches a value of 9 M. The equilibrium constant values (log Kcx) for the formation of U0 2

No abstract

No abstract

No abstract

Distribution data for U(VI) and Pu(IV) from 3.5 M nitric acid medium with 0.5 M N,N-dihexyl derivatives of hexanamide (DHHA), octanamide (DHOA) and decanamide (DHDA) in n-dodecane have been obtained in the temperature ränge 20-50 °C. From these data, the enthalpy, entropy and free energy changes associated with their extraction reactions were evaluated by the temperature coefficient method. Results indicate that the extraction reactions of U(VI) and Pu(IV) with all the three amides are predominantly enthalpy stabilised.