title: Uranyl ion extraction with conventional PUREX/TRUEX ligands assessed by electroanalytical chemistry at micro liquid/liquid interfaces.
abstract: The facilitated ion transfer (FIT) of uranyl or dioxouranium (UO(2)(2+)) was studied electrochemically using a micro interface between two immiscible electrolytic solutions (micro-ITIES) in order to evaluate the complexation stoichiometry and complexation constants (β) of two widely used ligands in spent fuel reprocessing: tributylphosphate (TBP) and octyl(phenyl)-N,N-diisobutylcarbamoylmethyl-phosphine oxide (CMPO). For the first time, discrete interfacial complexation reaction steps of varying uranyl to the two ligands ratios were resolved using the micro-ITIES hosted at the tip of a 25 μm diameter glass capillary. Two stoichiometries for UO(2)NO(3)TBP(n)(+) were determined including n = 3 and 4 with β values of 3.2 × 10(11) and 3.9 × 10(13), respectively. Subsequently, three distinct complexation reactions of CMPO with UO(2)(2+) were discovered corresponding to UO(2)NO(3)CMPO(2)(+), UO(2)NO(3)CMPO(3)(+), and UO(2)CMPO(5)(2+) whose respective complexation constants were determined to be 8.0 × 10(11), 8.8 × 10(14), and 6.5 × 10(32). The participation of nitrate anions in these complexation reactions is also discussed.
authors.affiliation: Department of Chemistry, The University of Western Ontario, Chemistry Building, 1151 Richmond Street, London, Ontario, Canada N6A 5B7.
authors.forename: Tom J
authors.initials: TJ
authors.lastname: Stockmann
authors.forename: Zhifeng
authors.initials: Z
authors.lastname: Ding
mesh_terms: D002623:Chemistry Techniques, Analytical; D007477:Ions / Q000737:chemistry / Q000302:isolation & purification; D008024:Ligands; D009942:Organometallic Compounds / Q000737:chemistry / Q000302:isolation & purification; D010087:Oxides / Q000737:chemistry / Q000302:isolation & purification*; D014501:Uranium / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D007477:Ions; D008024:Ligands; D009942:Organometallic Compounds; D010087:Oxides; C510902:dioxouranium(VI); D014501:Uranium