Extraction of UO 22+ by two hindered (GO) (ClCH 2)PO(OH) extractants, in benzene and n-heptane diluents, from aqueous chloride and nitrate phases

Abstract

The extraction of U(VI) from an aqueous mineral acid phase by a hindered (GO)(ClCH 2)PO(OH) extractant in a carrier diluent was studied as a function of the hydrogen ion concentration in the aqueous phase, steric hindrance within the extractant molecule, nature of the carrier diluent and composition of the aqueous phase. The two extractants were 2,6-iso-propyl phenyl chloromethyl phosphonic acid, [2,6-( i-C 3H 7) 2C 6H 3O] (ClCH 2)PO(OH), symbolized as H(2,6-Pφ)[( CIM) P] and 2,6-sec-butyl phenyl chloromethyl phosphonic acid, [2,6-( s-C 4H 9) 2C 6H 3O] (ClCH 2)PO(OH), symbolized as H(2,6-sBφ)[( ClM) P]. The carrier diluents were benzene and n-heptane. The aqueous phases were 1.00 F(HCl + NaCl) and 1.00 F(HNO 3 + NaNO 3). The extractant and hydrogen ion dependencies were found to be 2.0-power, respectively. Comparison of extraction of U(VI) in terms of the various parameters show the following ratios of K s values: H(2,6- iPφ) [(ClM)P]/H(2,6-sBφ)[(ClM)P], 2.5; in n-heptane/in benzene, 10; and from NO 3 −/from Cl −, 1.5. The K s is defined by the expression K= K sF 2 [H] +] 2 where K is the distribution ratio, F is the concentration of extractant in the organic phase, [H +] is the concentration of H + in the aqueous phase and K s is a constant characteristic of the system.