||Effects of humic substances on metal speciation /
Perdue, E. Michael
||Georgia Inst. of Tech., Atlanta. School of Geophysical Sciences.;Environmental Research Lab., Athens, GA. Office of Research and Development.
|| U.S. Environmental Protection Agency, Office of Research and Development, Environmental Research Laboratory,
Humic acids ;
Aquatic biology ;
Water treatment ;
Complex ions ;
Water pollution ;
Chemical reactions ;
Heavy metals ;
||Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy.
||17 pages ; 28 cm
The heterogeneity of ligands in a humic substance not only complicates the mathematical description of equilibrium data but also makes the complexation capacity of humic substances almost impossible to determine accurately. Complexation capacities (meq/g) of humic substances are widely reported to vary with pH, ionic strength, concentration of the humic substances used in the measurement, and nature of the metal being studied. By analogy with the behavior of a simple ligand (citrate), the chapter demonstrates that the reported effect of humic-substance concentration on complexation capacity is probably an artifact and that other experimental parameters affect conditional concentration quotients for metal complexation reactions. These effects create the illusion that complexation capacity is a function of pH, ionic strength, and nature of the added metal ion.
"EPA/600/D-89/048." "Reprint article published in Chapter 19 in Aquatic Humic Substances: Influence on Fate and Treatment of Pollutants. I.H. Suffett and P. Mac Carthy (eds). American Chemical Society, Washington DC. Advances in Chemistry Series No. 219, 1989, pp. 281-295." Microfiche.