US EPA

1433079 

Journal Article 

Dioxouranium(VI)-carboxylate complexes. Interaction of UO22+ with 1,2,3,4,5,6-benzenehexacarboxylate (mellitate) in 0 <= I(NaClaq)<= 1.0mol center dot L-1 

Crea, F; De Robertis, A; De Stefano, C; Sammartano, S 

2007 

Yes 

Journal of Solution Chemistry
ISSN: 0095-9782
EISSN: 1572-8927 

36 

4 

479-496 

10.1007/s10953-007-9124-7 

WOS:000246150200005 

The formation constants of dioxouranium(VI)-1,2,3,4,5,6 benzenehexacarboxy- late [mellitate(6-)] complexes were determined in NaCl aqueous solutions at
0.1 <= I <= 1.0 mol center dot L-1 and t = 25 degrees C by ISE-[H+] glass-electrode
potentiometry. The speciation model obtained at each ionic strength includes the following
species: ML4-, MLH3-, MLH2-/(2), MLH ((3)) over bar, M2L2-, MLOH5- and ML(OH)(6-)/(2) (M = UO2+/
(2) and L6- = mellitate). The ionic strength dependence of the protonation constants of mellitate
and of the metal-ligand complexes was investigated using the SIT (Specific Ion Interaction
Theory) approach. Formation constants at infinite dilution are [for the generic equilibrium pUO
(2+)/(2) + q(L6-) + rH(+) = (UO2+/(2)) (p)(L)(q)Hr((2p-6q+r)); beta(pqr)]: log(10)beta(110) =
10.155, log(10)beta(111) = 16.084, log(10) beta(112) = 20.749, log(10)beta(113) = 24.038, log
(10)beta(210) = 17.936, log(10)beta(11-1) = 2.327 and log(10) beta(11-2) = -6.804. Simple linear
relationships between the formation constants and the stoichiometric coefficients of reactants
are reported. The sequestering capacity of mellitate towards UO2+/(2) supercript stop was
quantified using a sigmoid Boltzman-type equation. 

dioxouranium(VI); 1,2,3,4,5,6-benzenehexacarboxylic acid; speciation; complex formation constants; SIT; sequestration