Effect of the nature of organophosphorous acid moiety on co-extraction of U(VI) and mineral acid from aqueous solutions using D2EHPA, PC88A and Cyanex 272

• Distribution coefficients of U(VI) and HNO3 increase with –OR moieties in ligands.
• The extraction of U(VI) by D2EHPA follows in the order HNO3 > HCl > H2SO4.
• The ratio of the rate of U(VI) and HNO3 extraction is D2EHPA > PC88A > Cyanex 272.

The effect of organophosphorous moieties of three acid ligands, D2EHPA, PC88A and Cyanex 272, dissolved in light liquid paraffin, on extraction of U(VI) and mineral acid was studied using the Bulk-Liquid Membrane (BLM) technique. A kinetic model was developed to predict the concentration of acid and U(VI) in the feed, organic and the strip phases during extraction. Acid extraction by complexing ligands was found to be significant. The extraction of U(VI) by these three acidic ligands in different mineral acids followed the order HNO3 > HCl > H2SO4. The distribution coefficient for acid and U(VI) extraction increased with increase in ‘–OR’ moieties in the acid ligands i.e. in the order D2EHPA > PC88A > Cyanex 272. The suitability of a ligand for liquid emulsion membrane (LEM) application depends upon the ratio of rates of extraction of U(VI) and acid (HNO3). The study showed that the ratios are in the order D2EHPA > PC88A > Cyanex 272.