Effect of pH on Stability Constants of Sr(II)-Humate Complexes
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The apparent stability constant, β, for the complexation of Sr(II) with humic acid (HA) was determined by a dialysis method in the pH range from 4 to 10 at the ionic strength of 0.1mol/dm<SUP>3</SUP> (NaClO<SUB>4</SUB>) at 298K under N2 atmosphere. It was found that log β increased with pH from 2.5 at pH 4.0 to 4.1 at pH 10.0. The log β tended to level off at higher pHs, indicating that saturation was being reached. Further, the apparent ligand to metal ratio was found to be 1.15±0.10. Dissociation of carboxylic and phenolic groups of HA with pH is probably the main factor that gives rise to the changes in stability constants.
- Journal of Nuclear Science and Technology
Journal of Nuclear Science and Technology 35(8), 579-583, 1998-08-25
Atomic Energy Society of Japan