The hydrogen salicylate ion as ligand. Complex formation equilibria with dioxouranium (VI), neodymium (III) and lead (II)

The complexation equilibria of the hydrogen salicylate ion, HL(-), have been studied, at 25 degrees C, by potentiometric measurements with a glass electrode in 1 M NaClO4 for uranyl and Nd(III) ions and in 3 M NaClO4 for Pb(II) ion. The ligand concentration (CL) was varied between 10(-3) and 0.05 M. In the system with U(VI) the concentrations ranged between: 10(-3) < or = U(VI)] < or = 0.01 M, 0.5 < or = CL /U(VI)] < or = 10 and 10(-2) < or = H+] < or = 10(-5) M; for neodymium system: 2 x 10(-3) < or = Nd(III)] < or = 0.01, 1 < or = CL /Nd(III)] < or = 10 and 10(-2) < or = H+] < or = 10(-7) M; for lead system: 10(-3) < or = Pb(II) < or = 3 x 10(-3), 1 < or = CL /Pb(II)] < or = 2 and 10(-5) < or = H+] < or = 10(-7.3) M. The experimental data have been explained with the formation of UO2HL+, UO2L, UO2(OH)L(-), (UO2)2(OH)L2(-) UO2(HL)L(-), NdHL(2+), NdL(+), Nd(OH)L, PbHL(+), PbL and PbL2(2-). Equilibrium constants are given for the investigated ionic media and at infinite dilution.