Comprehensive Thermodynamic Model Applicable to Highly Acidic to Basic Conditions for Isosaccharinate Reactions with Ca(II) and Np(IV)

Thermodynamics of Np(IV) complexes with gluconic acid under alkaline conditions: sorption studies

“…In analogy with ISA [4,10], and consistently with other tetravalent actinides such as Th(IV) [7], Np(IV)-GLU complexation in the absence of Ca can be described by the general reaction:…”

Thermodynamic Model for ThO2(am) Solubility in Isosaccharinate Solutions

“…The base line thermodynamic data for Th and other species, some of the associated ion-interaction parameters, and the computerized SIT fitting code (NONLINT-SIT) used in these interpretations are described in [9] and/or [1]. for lactonization constant that we determined based on the intrinsic protonation constant value [15] and the fits to the solubility data of Ca(ISA) 2 (cr)) [10], the only other value reported for this reaction is log 10 K 0 = 0.84 ± 0.04 by [14]. The differences in these values result from the differences in the value of protonation constants used in these calculations.…”

“…The authors interpreted their results using only Th(ISA) n 4-n species. Because the study was conducted at just one hydrogen ion concentration, it would be impossible to determine whether their experimental data could also have been interpreted equally well using mixed hydroxy-ISA complexes of thorium, especially considering that 1) thorium like other tetravalent actinides strongly hydrolyzes [9] even under fairly acidic conditions and 2) mixed hydroxy complexes containing ISA and other strongly complexing ligands (such as EDTA) have been reported for other tetravalent actinides [e.g., Np(IV) and Pu(IV)] [10,11]. In addition, it is possible that the nature and type of dominant complexes are different not only at the H + concentrations other than the one investigated in their study but also at those used in their study.…”

Evaluation of equilibrium constants for deprotonation and lactonisation of α-D-isosaccharinic acid

“…1 Each of these forms produces a related cyclic molecule, a lactone (ISL) in which the isosaccharinic acid loses a water molecule. HISA is a cellulose degradation product [1][2][3][4] and is known to form strong complexes with many elements (e.g., Th, U, Np, Pu, and Am) of interest in nuclear wastes (e.g., [3,[5][6][7][8][9]). Significant quantities of HISA may be produced by degradation of cellulose in low level nuclear waste (LLW) repositories [1] so HISA-mediated mobilisation of radionuclides from LLW is of potential environmental concern.…”

“…A large number of investigators using several different experimental techniques [potentiometric, 13 C nuclear magnetic resonance (NMR), and electrophoresis] have reported values for acidity (Equation (1)) [7,[13][14][15][16][17][18] and lactonisation (transformation of α-Disosaccharinic acid to α-D-isosaccharinate-1,4-lactone) (Equation (2)) [5,13,19] constants. The reported log 10 K • values for acidity constants (Equation (1)) for α-Disosaccharinic acid vary from −3.27 to −4.04 (Tables 1 and 2).…”