Publication detail

New Method for Determination of pKa of Humic Acid

KLUČÁKOVÁ, M. KOLAJOVÁ, R.

Original Title

Type

conference paper

Language

English

Original Abstract

New method of the determination of pKa is presented. The UV/VIS spectra of organic compounds with acidic groups depend on the pH of solution, because acidic and alkaline mediums, in which these compound are dissolved, shift the dissociation equilibrium of organic compounds towards nondissociated (macro)molecules or completely dissociated particles. This spectroscopic method is based on the shift of shape and intensity of absorbance spectra at the changes of pH of solution. The aim of this work is to characterize and to determine dissociation constants of lignitic humic acids in water by this methods and comparison of obtained results with those of classical one. It was found out that after the modification it was possible to use the spectrophotometry method for the determination of pKa of these substances, while the use of method was verified within the three different samples of humic acids. The optimal ratio humic acids/water and the extent of wavelength for measuring UV/VIS spectra were determined. It was proved that the values of pKa determinated by these methods better describe the real dissociation behaviour of humic acids in water than traditional Henderson-Hasselbach method. The UV/VIS spectra gained in combination with the results of pH measuring and the conductivity next showed the differences in the behaviour of differently prepared samples of humic acids.

Keywords

Humic acids, pKa, dissociation, total acidity

Authors

KLUČÁKOVÁ, M.; KOLAJOVÁ, R.

RIV year

2011

Released

1. 6. 2011

Publisher

VŠB-TU Ostrava

Location

Ostrava

ISBN

978-80-248-2387-4

Book

Proc. 15th Internationl Conference on Environment and Mineral Processing. Part I -III

Pages from

225

Pages to

229

Pages count

BibTex

@inproceedings{BUT72376,
  author="Martina {Klučáková} and Romana {Kratochvílová}",
  title="New Method for Determination of pKa of Humic Acid",
  booktitle="Proc. 15th Internationl Conference on Environment and Mineral Processing. Part I -III",
  year="2011",
  pages="225--229",
  publisher="VŠB-TU Ostrava",
  address="Ostrava",
  isbn="978-80-248-2387-4"
}