Dissociation ability of humic acids: Spectroscopic determination of pKa and comparison with multi-step mechanism.

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216305%3A26310%2F14%3APU108195" target="_blank" >RIV/00216305:26310/14:PU108195 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1016/j.reactfunctpolym.2014.02.005" target="_blank" >http://dx.doi.org/10.1016/j.reactfunctpolym.2014.02.005</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.reactfunctpolym.2014.02.005" target="_blank" >10.1016/j.reactfunctpolym.2014.02.005</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Dissociation ability of humic acids: Spectroscopic determination of pKa and comparison with multi-step mechanism.

Popis výsledku v původním jazyce

Humic acids are operationally defined as the fraction of humic substances which is not soluble under acidic conditions. This, does not mean, however, that their solid particles easily dissolve in water. Experimental results suggest that the dissolving of solid humic acids in an aqueous environment is more complex than the conventional solubility behaviour of sparingly soluble solids. The multi-step mechanism of their interaction with water includes partial equilibrium dissolution as well as direct equilibrium dissociation from the solid state. In this work, the pKa value of the dissolved humic acid fraction was determined on the basis of changes in the shape and intensity of their UV/VIS spectra measured in media with various values of pH. The shape of the spectra depends on the pH value, because acidic and alkaline media, in which these compounds are dissolved, shift their dissociation equilibrium towards non-dissociated molecules or to completely dissociated species. The aim of this work was to characterize the dissociation behaviour of selected humic samples by means of dissociation constants using this method. It was shown that the obtained values of pKa characterize the real dissociation behaviour of humic acids in an aqueous environment and can be used as the mean or effective value of pKa corresponding with the multi-step mechanism of dissociation of humic acids.

Název v anglickém jazyce

Dissociation ability of humic acids: Spectroscopic determination of pKa and comparison with multi-step mechanism.

Popis výsledku anglicky

Humic acids are operationally defined as the fraction of humic substances which is not soluble under acidic conditions. This, does not mean, however, that their solid particles easily dissolve in water. Experimental results suggest that the dissolving of solid humic acids in an aqueous environment is more complex than the conventional solubility behaviour of sparingly soluble solids. The multi-step mechanism of their interaction with water includes partial equilibrium dissolution as well as direct equilibrium dissociation from the solid state. In this work, the pKa value of the dissolved humic acid fraction was determined on the basis of changes in the shape and intensity of their UV/VIS spectra measured in media with various values of pH. The shape of the spectra depends on the pH value, because acidic and alkaline media, in which these compounds are dissolved, shift their dissociation equilibrium towards non-dissociated molecules or to completely dissociated species. The aim of this work was to characterize the dissociation behaviour of selected humic samples by means of dissociation constants using this method. It was shown that the obtained values of pKa characterize the real dissociation behaviour of humic acids in an aqueous environment and can be used as the mean or effective value of pKa corresponding with the multi-step mechanism of dissociation of humic acids.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10403 - Physical chemistry

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2014

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

REACTIVE & FUNCTIONAL POLYMERS

ISSN

1381-5148

e-ISSN

1873-166X

Svazek periodika

78

Číslo periodika v rámci svazku

1

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

6

Strana od-do

1-6

Kód UT WoS článku

000335274400001

EID výsledku v databázi Scopus

2-s2.0-84896287981