Extraction of uranium from non-complexing medium in chloroform using polymethylene bis-(acylpyrazolols) as extractants

Abstract

The extraction of UO 2 2+ with the extractant α,ω-bis-(1′-phenyl-3′-methyl-5′-hydroxy-pyrazol-4′-oyl) alkane, ‘HL- n-LH’ with n, number of methylene CH 2 links, HL-4-LH (with a short polymethylene chain), has been described for a wide range of solution concentration at acid pH and compared to its extraction with HL-8-LH (with a long polymethylene chain). The efficient extraction of uranium (10 −3 M) from its aqueous acid solution was prevented by the appearance of a third phase and loss of uranium with the shorter chain length HL-4-LH. The results demonstrated a non quantitative distribution which is not found with HL-8-LH, in the same experimental conditions. The aim of this work is to make a contribution by trying to solve the third phase problem. The very low detection limits of energy dispersive X-ray fluorescence (EDXRF) allowed dilutions, by using the concentration range 4×10 −3–2×10 −2 M for HL-4-LH in CHCl 3 as organic phase and [UO 2 2+]=10 −4 M from perchlorate medium (Na, H) +C1O 4 − 1 M as aqueous phase and the titration of aqueous and organic extraction phases, for the systems UO 2 2+, (Na, H) +CIO 4 − 1 M, aqueous/HL-4-LH, diluent, was performed adequately. The extraction efficiency of uranium for HL-8-LH was better across the concentration range 0.5×10 −2–4×10 −2 M at low pH than for HL-4-LH. The extracted complexes were UO 2(L-4-LH) 2, [UO 2(L-4-L)] 2, UO 2(L-8-L), UO 2(L-8-LH) 2, [UO 2(L-8-L)] 2.