Acidity of humic acid related to its oxygen-containing functional groups

Authors

  • Tatjana Anđelković Department of Chemistry, Faculty of Science and Mathematics, University of Niš, Višegradska 33, 18000 Niš
  • Jelica Perović Department of Chemistry, Faculty of Science and Mathematics, University of Niš, Višegradska 33, 18000 Niš,
  • Srđan Blagojević Faculty of Agriculture, University of Belgrade, Nemanjina 6, 11081 Belgrade
  • Milovan Purenović Department of Chemistry, Faculty of Science and Mathematics, University of Niš, Višegradska 33, 18000 Niš
  • Ružica Nikolić Department of Chemistry, Faculty of Science and Mathematics, University of Niš, Višegradska 33, 18000 Niš
  • Aleksandar Bojić Department of Chemistry, Faculty of Science and Mathematics, University of Niš, Višegradska 33, 18000 Niš
  • Darko Anđelković Water Work Association "Naissus", Kneginje Ljubice 1/1, 18000 Niš

DOI:

https://doi.org/10.20450/mjcce.2006.297

Keywords:

humic acid, acid-base titration, Henderson-Hasselbalch equation, oxygen-containing functional group content

Abstract

Acidic properties of polyprotic acids, such as humic acid, can be described quantitatively with potentiometric titration interpreted with the modified Henderson-Hasselbalch equation. Oxygen-containing functional groups such as carboxylic, phenolic, and alcoholic groups are the most important groups that contribute to acidity of humic acid. Those groups in isolated soil humic acid are selectively blocked by methylation with CH3I/Ag2O in dimethylformamide. The obtained values for acidic group contents, the apparent and intrinsic dissociation constants for underivatized and derivatized HAs, provide direct evidence on the oxygen-containing functional groups contribution to HA acidity, especially the contribution of alcoholic hydroxyls, which is usually neglected and ascribed to phenolic groups content.

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Published

2006-12-14

How to Cite

Anđelković, T., Perović, J., Blagojević, S., Purenović, M., Nikolić, R., Bojić, A., & Anđelković, D. (2006). Acidity of humic acid related to its oxygen-containing functional groups. Macedonian Journal of Chemistry and Chemical Engineering, 25(2), 131–137. https://doi.org/10.20450/mjcce.2006.297

Issue

Vol. 25 No. 2 (2006)

Section

Organic Chemistry

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