scholarly journals Modelling the Water Sorption Isotherms of Warionia Saharae and determination of sorption heats and drying kinetics

2018 ◽  
Author(s):  
Fedol Amel ◽  
A. Cheriti
Keyword(s):  
Moisture Content ◽  
Water Content ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Storage Conditions ◽  
Drying Kinetics ◽  
Equilibrium Water Content ◽  
Clapeyron Equation

The hygroscopic equilibrium of Warionia saharae was studied, which allowed getting an idea of ​​the equilibrium water content relative to a given humidity. The results of this study made it possible to have the sorption curves. The results of this study made it possible to obtain the sorption curves necessary for know the storage conditions of the plant and the study of its drying kinetics. The static gravimetric method was used to determine sorption isotherms of Warionia saharae leaves at 30and 40 ◦C and in the range of water activity varying from 0.063 to 0.898.  The Gab, Peleg models was found to be the most suitable for describing the sorption curves. The isosteric heat calculated by applying the Clausius–Clapeyron equation .The desorption isosteric heat was higher than the isosteric heat of adsorption and both decreased continuously with increasing of the equilibrium moisture content. The experimental results obtained allowed us to determine the temporal evolution of the drying kinetics as a function of the moisture content. The curve of the evolution of the water content as a function of time shows the absence of the phases product temperature and constant drying rate Keywords: Sorption isotherm, isosteric heats, modelling, kinetics, Warionia saharae.  

scholarly journals Solar convective drying kinetics and sorption isotherms of Citrus aurantium flowers

2018 ◽  
Author(s):  
Naji Abdenouri ◽  
Hicham El Ferouali ◽  
Ahmed Zoukit ◽  
Said Doubabi
Keyword(s):  
Moisture Content ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Storage Conditions ◽  
Drying Kinetics ◽  
Convective Drying ◽  
Citrus Aurantium ◽  
Peleg Model ◽  
Drying Kinetic ◽  
Drying Curves

Citrus aurantium flowers are high value aromatic and medicinal plants. The storage conditions and quality of dried Citrus aurantium flowers depends on their hygroscopic stability. The equilibrium moisture content was determined at temperatures (from 30 to 60 °C), and the sorption phenomenon is well described by Peleg model. The optimal water activity for the storage of the product was estimated at awop=0.373. Afterwards, the net isosteric heat was evaluated in the range of 88 kJ.mol−1 for small values of the moisture content (Xeq=0.14kg water/kg d.b), and it decreased along with the increase of Xeq. The experimental drying curves showed only a falling rate period. Finally, Midilli-Kucuk model was found to be the more suitable to describe the drying kinetic of Citrus aurantium flowers. Keywords: Drying kinetics; Solar energy; Modeling; Citrus aurantium; Sorption isotherms; Conservation process

Thermodynamic properties of water sorption isotherms of grape seed

2014 ◽  
Vol 28 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Kamran Maleki Majd ◽  
Seyed H. Karparvarfard ◽  
Asgar Farahnaky ◽  
Sara Ansari
Keyword(s):  
Experimental Data ◽  
Water Activity ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Isosteric Heat ◽  
Grape Seed ◽  
Clapeyron Equation ◽  
Moisture Sorption Isotherm ◽  
Best Fit

Abstract In this study the moisture sorption isotherm of grape seed was determined by using a static gravimetric method at 35-65°C and 0.108-0.821 water activity range. The sorption isotherms were found to be typical sigmoid shape of most food materials. Five models including the Brunauer-Emmett-Teller (2-parameter), Guggenheim, Anderson and De Boer (3-parameter), Oswin (2-parameter), Ferro-Fontan (3-parameter) and Peleg (4-parameter) models were considered to fit the experimental data. The Ferro- Fontan and Peleg equations (at three temperatures 35, 45, 65°C) having R2 greater than 0.97 and lower values of standard error of estimate and deviation modulus gave the best fit of the experimental data throughout the entire range of water activity. The net isosteric heat of sorption, calculated by Calusius-Clapeyron equation on experimental data, was found to be a polynomial and exponential function of equilibrium moisture content within the temperature range investigated.

scholarly journals Moisture Sorption Isotherms And Thermodynamic Properties Of Urtica Dioica Leaves

2016 ◽  
Vol 12 (24) ◽  
pp. 376 ◽  
Author(s):  
Abdelkader Lamharrar ◽  
Ali Idlimam ◽  
Mohammed Kouhila ◽  
Lamya Lahnine ◽  
Hind Mouhanni
Keyword(s):  
Water Activity ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Storage Conditions ◽  
Urtica Dioica ◽  
Endemic Plant ◽  
Clapeyron Equation ◽  
Moisture Sorption Isotherms ◽  
Different Temperatures

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.

scholarly journals Determination of desorption isotherms, latent heat and isosteric heat of pequi diaspore

2016 ◽  
Vol 20 (5) ◽  
pp. 493-498 ◽  
Author(s):  
Kelly A. de Sousa ◽  
Osvaldo Resende ◽  
Bruno de S. Carvalho
Keyword(s):  
Moisture Content ◽  
Latent Heat ◽  
Equilibrium Moisture Content ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Static Method ◽  
The One ◽  
Content Range ◽  
Water Sorption Isotherms

ABSTRACT The objective was to determine water sorption isotherms of diaspores of pequi fruits in order to obtain information on the amount of water that this product desorbs at the temperatures of 10, 20, 30 and 40 °C and water activities from 0.20 to 0.89, adjusting different mathematical models to experimental data, and to determine its latent heat and isosteric heat. The equilibrium moisture content was obtained through the indirect static method, using the device Hygropalm Model Aw 1. The Modified Henderson model was the one that best fitted the data and was selected to predict the equilibrium moisture content of pequi diaspore. It was observed that the higher the temperature for the same equilibrium moisture content (% d.b.), the higher the water activity values. As temperature values increased, there was a reduction in the vaporization latent heat of the product. Isosteric heat values of diaspores of pequi fruits in the moisture content range of 4.02 to 16.63 (% d.b.) varied from 2,776.49 to 2,558.39 kJ kg-1.

Analysis of Moisture Desorption Isotherms of Eggplant (Solanum melongena)

2010 ◽  
Vol 16 (5) ◽  
pp. 417-425 ◽  
Author(s):  
R. Moreira ◽  
F. Chenlo ◽  
M.D. Torres ◽  
N. Vallejo
Keyword(s):  
Moisture Content ◽  
Solanum Melongena ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Integral Enthalpy ◽  
Differential Enthalpy ◽  
Different Temperatures ◽  
Enthalpy And Entropy ◽  
Monolayer Moisture

Sorption isotherms of eggplant were determined employing, as experimental technique, a static gravimetric method, using saturated salt solutions to achieve the equilibrium. The experiments were carried out at different temperatures (20, 35, 50 and 65 °C). The sorption isotherms can be classified, according to Brunauer’s classification, as type II or III depending on temperature. Equilibrium moisture content data were correlated by two models usually applied to foodstuffs (Brunauer-Emmet-Teller (BET) and Halsey). BET model was employed to determine monolayer moisture content (0.121 kg/kg d.b.). Halsey model was selected by the goodness of fitting. Experimental data were analyzed by a thermodynamic approach to obtain some properties as net isosteric heat, equilibrium heat and differential and net integral entropy. The differential enthalpy and entropy decreased with increasing moisture content and satisfied the compensation theory. The net integral enthalpy and entropy showed maximum values (~31 kJ/mol and ~88 J/mol.K) at 0.093 (kg/kg d.b.) of moisture content.

scholarly journals Modelling of the sorption isotherms and determination of the isosteric heat of split pistachios, pistachio kernels and shells

2018 ◽  
Vol 36 (No. 3) ◽  
pp. 268-275 ◽  
Author(s):  
Sedighe Soleimanifard ◽  
Naser Hamdami
Keyword(s):  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Mean Square ◽  
Clapeyron Equation ◽  
Data Description ◽  
Maximum Value ◽  
Chi Squared ◽  
Gab Model ◽  
Thermodynamic Equations

We aimed to measure the equilibrium moisture content of the Ohadi variety of pistachio shells, pistachio kernels and split pistachios using gravimetric methods at 25, 40, 55, and 70°C and saturated salt solutions with water activities ranging from 0.08 to 0.97. Then, 11 mathematical models were used to select the best model for data description. The GAB model, which had the maximum value for the correlation coefficient (R<sup>2</sup>) and minimum values for the chi-squared test (χ<sup>2</sup>) and root mean square error (RMSE), was identified as the best model for split pistachios and pistachio kernels. The Caurie model, meanwhile, was identified as the best model for pistachio shells. In this test, there was no significant hysteresis between the desorption and adsorption curves. Furthermore, the isosteric heat of adsorption and desorption were also determined using thermodynamic equations (e.g., the Clausius-Clapeyron equation).

scholarly journals Hygroscopicity of baru (Dipteryx alata Vogel) fruit

2017 ◽  
Vol 21 (4) ◽  
pp. 279-284 ◽  
Author(s):  
Daniel E. C. de Oliveira ◽  
Osvaldo Resende ◽  
Lílian M. Costa ◽  
Weder N. Ferreira Júnior ◽  
Silva Igor O. F.
Keyword(s):  
Moisture Content ◽  
Water Content ◽  
Equilibrium Moisture Content ◽  
Gravimetric Method ◽  
Isosteric Heat ◽  
Water Desorption ◽  
Safe Storage ◽  
Moisture Contents ◽  
Desorption Isotherms ◽  
Dipteryx Alata

ABSTRACT With the knowledge on the hygroscopic equilibrium of the baru (Dipteryx alata Vogel) fruit, the product can be adequately handled to maintain the moisture content at the levels recommended for safe storage. Thus, this paper aimed to determine the water desorption isotherms of baru fruits at temperatures of 20, 25, 30 and 35 °C, and water activity between 0.14 and 0.80, and obtain the values of isosteric heat of desorption as a function of the equilibrium moisture content of the product. The equilibrium moisture content was obtained using the static-gravimetric method. Modified Halsey was the best model recommended to represent the hygroscopicity of baru fruits. The recommended moisture contents for safe storage of baru fruits are not more than 19.9, 19.3, 18.6 and 18.0 (%, d.b.) for the respective temperatures of 20, 25, 30 and 35 °C. The integral isosteric heat of desorption increases as the water content decreases, leading to an increment in the energy required to remove water from the product.

Experimental Determination and Modeling of Desorption Isotherms of the Tomato "Lycopersicum esculentum"

2021 ◽  
pp. 24-31
Author(s):  
Roland Lankouande ◽  
G. Gilbert Nana ◽  
Souleymane Ouedraogo ◽  
Kalifa Palm ◽  
Frédéric Ouattara ◽  
...  
Keyword(s):  
Experimental Determination ◽  
Experimental Studies ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Storage Conditions ◽  
Market Place ◽  
Desorption Isotherms ◽  
Final Water Content ◽  
The Stability

The aim of this work is to make a contribution to the drying of tomatoes. The purpose of this contribution is the experimental determination of the desorption isotherms of a variety of tomato (one of the most widespread on the Burkinabe market place) using the static gravimetric method at temperatures of 25°C, 40°C and 50°C. It is more specifically a question of validating a theoretical model based on these experimental studies. Sorption isotherms allow us to have information to establish the stability of food products and their storage conditions. These isotherms are curves which give valuable information on the hygroscopic balance of a product because they allow to know its range of stability after drying by determining the final water content.

Moisture Sorption Isotherms of Osmotically Dehydrated Sweet Pepper

2007 ◽  
Vol 3 (5) ◽  
Author(s):  
Jatindra Kumar Sahu ◽  
Ajita Tiwari
Keyword(s):  
Moisture Content ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Isosteric Heat ◽  
Sweet Pepper ◽  
Coefficient Of Determination ◽  
Clapeyron Equation ◽  
Moisture Sorption Isotherm ◽  
Moisture Sorption Isotherms ◽  
Monolayer Moisture

Moisture sorption isotherms of osmotically dehydrated sweet peppers were determined at 15oC, 30oC and 40oC using static desiccator techniques. In the study, seven levels of water activity in range of 0.08 to 0.91 were used by the use of saturated salt solutions. The isotherms were found to be sigmoid type and of BET classification II. Out of seven sorption models i.e. BET, modified BET, Hasley, Caurie, GAB, Oswin and Smith, fitted to the experimental data, Oswin model was found to be the best for accurate prediction of moisture sorption isotherm with highest value of coefficient of determination (R2) and lowest values of standard error (SE) and relative deviation parentage (Rd). The value of monolayer moisture content of the osmotically dehydrated sweet pepper was found to be 3.037%, 3.934% and 4.432% (db) at 15oC, 30oC and 40oC respectively. The values of net isosteric heat of sorption as calculated by Clausius–Clapeyron equation showed a regular fall with increase in moisture content.

scholarly journals Experimental Determination and Modeling of the Moisture-Sorption Isotherms and Isosteric Heat of Tobacco Leaves

2021 ◽  
Vol 20 (5) ◽  
pp. 269-277
Author(s):  
Foullanine Meriama ◽  
Bennaceur Said ◽  
Loumani Akil ◽  
Mediani Ahmed ◽  
Moungar Houcine ◽  
...  
Keyword(s):  
Nicotiana Tabacum ◽  
Experimental Determination ◽  
Water Content ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Isosteric Heat ◽  
Nicotiana Tabacum L ◽  
Desorption Isotherms ◽  
Adsorption Desorption

During a forced convection sun drying and storage operation, the equilibrium water content of a product to be dried is critical. These figures are frequently derived using isothermal sorption curves. The calculation of isotherms is a necessary step in determining the distribution and intensity of water connections in products. for that this paper concentrates on the experimental determination of the adsorption-desorption isotherms for various temperatures (40, 50, and 60℃) of the Nicotiana Tabacum L plants. From which we had established the relationship between the water activity and the water content in the product. However, the aforementioned determination was carried out by the static gravimetric method. Eight saturated salt solutions have been utilized in applications such as (KOH, KCl, MgCl2, MgNO3, K2CO3, BaCl2, K2SO4, and NaCl). Hygroscopic equilibrium was completed after 13 days for temperature 40℃, 11 days for 50℃, and 9 days for 60℃. The overall experimental sorption curves are summarized by six models (HENDERSON, modified HALSEY, OSWIN, GAB, modified BET, and PELEG). The sorption isotherms built using the Clausius–Clapeyron equation were used to determine the net isosteric temperatures of desorption and adsorption of Nicotiana Tabacum L. The results for the adsorption-desorption isotherms found are type III according to IUAPC. Following the smoothing of the experimental results by different used models, it was found that the models of GAB and Peleg allow having the lowest mean relative errors and correlation coefficient.

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