Cupric Ion Complexation by Fulvic Acid Extracted from Sewage Sludge-Soil Mixtures1
- Garrison Sposito,
- Kenneth M. Holtzclaw and
- C. S. LeVesque-Madore2
The complexes formed between Cu2+ and fulvic acid extracted from sewage sludge were investigated by potentiometric titration of K/H fulvate with Cu(ClO4)3 at pH 5 and 25°C, in an ionic medium of 0.1M KClO4. Formation functions, giving the number of moles of Cu2+ bound per mole of K/H fulvate, were calculated from the titration data and plotted against the molar concentration of Cu2+, with the concentration of K/H fulvate being a fixed parameter for each plot. These functions were analyzed by the Scatchard plot method and were interpreted as evidence of: (i) a relatively strong 1:1 complex (log cK = 3.9) that is formed between Cu2+ and the most acidic functional groups in fulvic acid and (ii) a weaker set of complexes (log eK = 2) that is formed between Cu2+ and the more weakly acidic functional groups acting as both unidentate and bidentate ligands.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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