Equilibrium sorption isotherms and thermodynamic properties of starch and gluten

Viollaz, Pascual E.; Rovedo, Clara O.

doi:10.1016/s0260-8774(99)00066-7

Cited by 77 publications

(49 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In general, water sorption isotherms for starch products are analysed according to the BET model or its modifications, for instance the GAB (Guggenheim-Anderson-de Boer) equation. The BET model was found to be adequate only in the lower relative pressure range (<0.4), yet the GAB model was not appropriate for the estimation of monolayer capacity (Timmermann et al, 2001;Viollaz and Rovedo, 1999).…”

Section: Resultsmentioning

confidence: 94%

Adsorptive Properties of Biobased Adsorbents

2005

View full text Add to dashboard Cite

Water and methanol vapor adsorption isotherms for native and modified potato starch were investigated. For obtaining the best fit for the experimental data several models based on the BET approach was evaluated. The hypothesis that water is adsorbed on the starch granules at the primary and secondary adsorption sites as well as a concept considering the adsorbent fractality were also tested. It was found, that the equilibrium adsorption points in the examined range of relative humidity (0.03-0.90) were most accurately predicted by using a three-parameter model, proposed by Kats and Kutarov (1998). For methanol a good representation of experimental data was obtained using model proposed by Talu and Meunier (1996).

show abstract

Section: Resultsmentioning

confidence: 94%

Adsorptive Properties of Biobased Adsorbents

2005

View full text Add to dashboard Cite

show abstract

“…The isotherm fits were considered valid when the correlation coefficient (R) was higher than 0.990 and the root mean square error (RMSE) was lower than 4 % [32][33][34].…”

Section: Methodsmentioning

confidence: 99%

Thermodynamic analysis of water vapour sorption behaviour of juvenile and mature wood of Abies alba Mill.

et al. 2015

View full text Add to dashboard Cite

The hygroscopicity and thermodynamic properties of juvenile and mature wood of Abies alba Mill. were studied through the 15, 35 and 50°C sorption isotherms. The Guggenheim, Anderson and de Boer-Dent model was used to fit the isotherms. The thermodynamic parameters were obtained from the sorption isotherms by applying the integration method of the Clausius-Clapeyron equation. The chemical composition of both types of wood (extractives, lignin and carbohydrate polymer-cellulose and hemicellulose-content) was determined, and infrared spectroscopy and X-ray diffractograms were used to identify any chemical modifications and changes in the crystal structure of the cell wall. The mature wood has more cellulose and hemicellulose content and less extractives content than the juvenile wood. The shorter crystallite length in the mature wood creates a higher amount of amorphous zones and, as a consequence, a higher number of access areas to the -OH groups. The combination of these phenomena explains the different hygroscopic behaviour between the juvenile and the mature wood, as the latter has higher moisture content in the three isotherms. As regards the thermodynamic properties, the amount of energy involved in the sorption process is greater in the mature wood than in the juvenile wood.

show abstract

“…This model is particularly appropriate for obtaining a good fit in studies which include high relative humidities of over 90%, in which adsorption through capillarity and the multilayer effect play a relevant role [38]. The fit for GAB model corresponds to the equation:…”

Section: Methodsmentioning

confidence: 99%

“…The fit, both in desorption and adsorption, was regarded as valid if the regression coefficient R was greater than 0.990 and the RMS was less than 4% [2,12,38]. A hysteresis coefficient was used for comparing the isotherms of the old and the recently cut wood, as the values of this coefficient make it possible to know how much more stable the wood is in relation to the changes of relative humidity which cause the wood to change from a state of adsorption to desorption and vice versa:…”

Section: Methodsmentioning

confidence: 99%

Comparison of the hygroscopic behaviour of 205-year-old and recently cut juvenile wood fromPinus sylvestrisL.

et al. 2006

View full text Add to dashboard Cite

-The hygroscopic response of the juvenile wood of Pinus sylvestris L. from recently cut trees from the Valsaín Forest in Segovia, Spain (new wood) was compared to that of the juvenile wood of the same species used in roof rafters installed at the end of the eighteenth century (old wood), which came from the same forest. The 35 ºC isotherms were plotted using the saturated salts method, and the mathematical fit used was the GAB model. The infrared spectrums and the X-ray diffractograms were used in order to study the possible chemical variations and crystallinity indices of the cell wall. The adsorption-desorption loop of the old wood is above the loop of the new wood, although the hysteresis coefficient is higher in the old wood. The peaks corresponding to the -OH groups are similar, although the degree of crystallinity is significantly lower in the old wood. While cellulose crystallinity differs between the old and new wood, and has a major influence on wood hygroscopicity, other modifications in the amorphous components of the cell wall may have contributed to the changes in hygroscopicity between the old and new wood. hygroscopicity / sorption isotherm / juvenile wood / Fourier transform infrared spectroscopy (FTIR) / X-ray diffraction (XRD)Résumé -Comparaison du comportement hygroscopique d'un bois juvénile de Pinus sylvestris L. âgé de 205 ans avec celui d'un bois juvénile récemment coupé. La réponse hygroscopique du bois juvénile de Pinus sylvestris L. provenant d'arbres récemment coupés de la forêt de Valsaín en Segovia, Espagne (bois récent) a été comparée à celle de bois juvénile de la même espèce utilisé comme bois de charpente à la fin du XIII e siècle (vieux bois), originaire de la même forêt. Les isothermes de sorption à 35 ºC ont été obtenus par la méthode des sels saturés, et l'ajustement mathématique utilisé était le modèle GAB. La spectrographie infrarouge et la diffractométrie par rayons X-ont été utilisées pour étudier d'éventuelles différences de composition chimique et d'indices de cristallinité de la paroi cellulaire. La boucle d'adsorption-désorption du vieux bois est au-dessus de celle du bois récent, tandis que le coefficient d'hystérésis est plus élevé dans le vieux bois. Les pics correspondant aux groupes -OH sont similaires, bien que le degré de cristallinité soit significativement plus bas dans le vieux bois. Bien que ces différences de cristallinité puissent expliquer pour une bonne part le contraste hygroscopique entre bois vieux et actuel, des modifications au niveau des composés amorphes de la paroi peuvent également être invoquées. hygroscopicité / isotherme de sorption / bois juvénile / spectroscopie infrarouge par transformée de Fourier / diffraction par rayons X

show abstract

Equilibrium sorption isotherms and thermodynamic properties of starch and gluten

Cited by 77 publications

References 3 publications

Adsorptive Properties of Biobased Adsorbents

Adsorptive Properties of Biobased Adsorbents

Thermodynamic analysis of water vapour sorption behaviour of juvenile and mature wood of Abies alba Mill.

Comparison of the hygroscopic behaviour of 205-year-old and recently cut juvenile wood fromPinus sylvestrisL.

Contact Info

Product

Resources

About