Open AccessMoisture Sorption Isotherms And Thermodynamic Properties Of Urtica Dioica Leaves
Author(s) -
Abdelkader Lamharrar,
Ali Idlimam,
M. Kouhila,
Lamya Lahnine,
Hind Mouhanni
Publication year - 2016
Publication title -
european scientific journal
Language(s) - English
Resource type - Journals
eISSN - 1857-7881
pISSN - 1857-7431
DOI - 10.19044/esj.2016.v12n24p376
Subject(s) - sorption , urtica dioica , urticaceae , water activity , desorption , moisture , adsorption , gravimetric analysis , chemistry , enthalpy , thermodynamics , water content , environmental chemistry , botany , organic chemistry , geology , physics , biology , geotechnical engineering
Urtica dioica is a Moroccon endemic plant of used for its virtues in traditional medicine. Thus, it is necessary to study the effect of preservation processes on the storage conditions of the plant. The static gravimetric method was used to determine sorption isotherms of Urtica dioica leaves at three temperatures (40, 50 and 60 °C) and in the range of water activity ( w a ) ranging from 0.0572 to 0.898. Six mathematical models were used to fit the experimental data. The Enderby and Peleg models were found to be the most suitable for describing the sorption curves. The optimal water activity for conservation of Urtica dioica leaves was determined. Isosteric heats of desorption and adsorption were calculated by applying the Clausius- Clapeyron equation to the sorption isotherms at different temperatures; it decreased with increasing moisture content. A linear relation exists between the enthalpy and entropy of the sorption reaction.