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KLUČÁKOVÁ, M. KOLAJOVÁ, R.
Original Title
New Method for Determination of pKa of Humic Acid
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
5
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" }