<abstract xmlns="http://www.w3.org/1999/xhtml"> Complex formation between uranyl ion, UO22+, and a hydrophilic anionic form of SO3-Ph-BTP4- ligand, L4-, in water was studied by liquid-liquid extraction experiments performed over a range of the ligand and HNO3 concentrations in the aqueous phase, at a constant concentration of nitrate anions at 25°C . The competition for UO22+ ions between the lipophilic TODGA extractant and the hydrophilic L4- ligand leads to the decrease in the uranyl distribution ratios, D, with an increasing L4- concentration. The model of the solvent extraction process used accounts - apart from uranyl complexation by TODGA and SO3-Ph-BTP4- - also for uranyl complexation by nitrates and for the decrease in the concentration of the free L4- ligand in the aqueous phase, due to its protonation, bonding in the uranyl complex and the distribution between the two liquid phases. The unusually strong dependence of the D values on the acidity, found in the experiment, could hardly be explained as due to L4- protonation merely. Three hypotheses were experimentally tested, striving to interpret the data in terms of additional extraction to the organic phase of ion associates of protonated TODGA cation with either partly protonated anionic L4- ligands or anionic UO22+ complexes with NO3 - or L4-. None of them has been confirmed. The analysis of the results, based on the formal correction of free ligand concentrations, points to the formation of 1 : 1 and 1 : 2 uranyl - SO3-Ph-BTP complexes in the aqueous phase. The conditional formation constant of the 1:1 complex has been determined, logßL,1 = 2.95 ± 0.15. </abstract>

Complex formation between uranyl ion, UO22+, and a hydrophilic anionic form of SO3-Ph-BTP4- ligand, L4-, in water was studied by liquid-liquid extraction experiments performed over a range of the ligand and HNO3 concentrations in the aqueous phase, at a constant concentration of nitrate anions at 25°C . The competition for UO22+ ions between the lipophilic TODGA extractant and the hydrophilic L4- ligand leads to the decrease in the uranyl distribution ratios, D, with an increasing L4- concentration. The model of the solvent extraction process used accounts - apart from uranyl complexation by TODGA and SO3-Ph-BTP4- - also for uranyl complexation by nitrates and for the decrease in the concentration of the free L4- ligand in the aqueous phase, due to its protonation, bonding in the uranyl complex and the distribution between the two liquid phases. The unusually strong dependence of the D values on the acidity, found in the experiment, could hardly be explained as due to L4- protonation merely. Three hypotheses were experimentally tested, striving to interpret the data in terms of additional extraction to the organic phase of ion associates of protonated TODGA cation with either partly protonated anionic L4- ligands or anionic UO22+ complexes with NO3 - or L4-. None of them has been confirmed. The analysis of the results, based on the formal correction of free ligand concentrations, points to the formation of 1 : 1 and 1 : 2 uranyl - SO3-Ph-BTP complexes in the aqueous phase. The conditional formation constant of the 1:1 complex has been determined, logßL,1 = 2.95 ± 0.15.

Determination of formation constants of uranyl(VI) complexes with a hydrophilic SO3-Ph-BTP ligand, using liquid-liquid extraction

Centre for Radiochemistry and Nuclear Chemistry, Institute of Nuclear Chemistry and Technology, 16 Dorodna Str., 03-195 Warsaw, Poland, and RadioChemistry & Processes Department, Nuclear Energy Division, CEA, F-30207 Bagnols sur Cèze, France

Centre for Radiochemistry and Nuclear Chemistry, Institute of Nuclear Chemistry and Technology, 16 Dorodna Str., 03-195 Warsaw, Poland

RadioChemistry & Processes Department, Nuclear Energy Division, CEA, F-30207 Bagnols sur Cèze, France RadioChemistry & Processes Department, Nuclear Energy Division, CEA, F-30207 Bagnols sur Cèze, France

RadioChemistry & Processes Department, Nuclear Energy Division, CEA, F-30207 Bagnols sur Cèze, France

Nukleonika

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Determination of formation constants of uranyl(VI) complexes with a hydrophilic SO-Ph-BTP ligand, using liquid-liquid extraction

Complex formation between uranyl ion, UO22+, and a hydrophilic anionic form of SO3-Ph-BTP4- ligand, L4-, in water was studied by liquid-liquid extraction...

Determination of formation constants of uranyl(VI) complexes with a hydrophilic SO₃-Ph-BTP ligand, using liquid-liquid extraction

Publié en ligne: 30 déc. 2015

Pages: 821 - 827

Reçu: 03 juil. 2015

Accepté: 15 sept. 2015

DOI: https://doi.org/10.1515/nuka-2015-0150

Mots clés
uranyl ion, hydrophilic poly-N-dentate ligands, complexes, solvent extraction, stripping, formation constant

© by Lukasz Steczek

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Determination of formation constants of uranyl(VI) complexes with a hydrophilic SO3-Ph-BTP ligand, using liquid-liquid extraction

Publié en ligne: 30 déc. 2015

Pages: 821 - 827

Reçu: 03 juil. 2015

Accepté: 15 sept. 2015

DOI: https://doi.org/10.1515/nuka-2015-0150

Mots clésuranyl ion, hydrophilic poly-N-dentate ligands, complexes, solvent extraction, stripping, formation constant

© by Lukasz Steczek

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Determination of formation constants of uranyl(VI) complexes with a hydrophilic SO₃-Ph-BTP ligand, using liquid-liquid extraction

Mots clés
uranyl ion, hydrophilic poly-N-dentate ligands, complexes, solvent extraction, stripping, formation constant