The kinetics of non-isothermal dehydration of equilibrium swollen Ca-alginate hydrogel

Non-isothermal dehydration of Ca-alginate hydrogel was investigated for the first time. Thermogravimetric dehydration curves were recorded at heating rates from 5 to 20 K min −1 in the temperature range from 300 to 450 K. The dependence of apparent activation energy on the degree of dehydration was...

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Bibliographic Details
Published in:Journal of thermal analysis and calorimetry 2020-12, Vol.142 (5), p.2123-2129
Main Authors: Stankovic, Branislav, Jovanovic, Jelena, Adnadevic, Borivoj
Format: Article
Language:English
Subjects:
Activation energy
Alginates
Analysis
Analytical Chemistry
Chemistry
Chemistry and Materials Science
Dehydration
Heating rate
Hydrogels
Inorganic Chemistry
Measurement Science and Instrumentation
Parameters
Physical Chemistry
Polymer Sciences
Statistical models
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Summary:Non-isothermal dehydration of Ca-alginate hydrogel was investigated for the first time. Thermogravimetric dehydration curves were recorded at heating rates from 5 to 20 K min −1 in the temperature range from 300 to 450 K. The dependence of apparent activation energy on the degree of dehydration was determined by the Friedman’s differential isoconversion method. The experimental conversion curves of dehydration are fully fitted with the statistical model of hydrogel dehydration. The values of the parameters of the statistical model and their changes with the heating rate were determined. The rate constant as the function of temperature was calculated at all heating rates, and it was found that these dependencies obey the Arrhenius equation. From the values of rate constant, the changes in the kinetic parameters (activation energy and pre-exponential factor) of non-isothermal dehydration of Ca-alginate hydrogel with temperature and dehydration degree were calculated. The obtained results indicate the existence of two phase states of water absorbed on the hydrogel.
ISSN:1388-6150
1588-2926
DOI:10.1007/s10973-020-10020-6