scholarly journals Behavioural Change according to the Si/Al Ratio of Successive Na-Mordenites Observed through Their Dielectric Relaxation during Water Vapour Adsorption Process

2016 ◽  
Vol 2016 ◽  
pp. 1-10
Author(s):  
Sekou Diaby
Keyword(s):  
Dielectric Relaxation ◽  
Water Vapour ◽  
Adsorption Process ◽  
Behavioural Change ◽  
Exchangeable Cation ◽  
Relaxation Measurement ◽  
Simple Method ◽  
Adsorbed Molecules ◽  
Vapour Adsorption ◽  
Water Vapour Adsorption

The experimental study of water vapour adsorption phenomenon on a zeolite, by dielectric relaxation measurement, makes it possible to determine the variations in the exchangeable cation hopping activation energy, on the surface of the solid, in relation to the number of adsorbed molecules. The present work shows that it is possible to explain the change observed in the energy, by means of simple assumptions based, on the one hand, on the models used in order to simulate the adsorption process and, on the other hand, on the distribution of the molecules adsorbed near the exchangeable cations. Thus, the phenomenological interpretation suggested here, about the change in the exchangeable cation hopping energy, obtained by dielectric relaxation measurement, makes us with a mind to conceive a simple method for explaining the results leading to new information on the organization of the first adsorbed molecules on the surface of the studied zeolite. Then, it can be verified that these conclusions confirm the assumptions already developed for interpreting the inferences from previous experiments carried out by means of other techniques.

scholarly journals Kinetic model of water vapour adsorption by gluten-free starch

2015 ◽  
Vol 29 (1) ◽  
pp. 115-119
Author(s):  
Aneta Ocieczek ◽  
Robert Kostek ◽  
Millena Ruszkowska
Keyword(s):  
Water Content ◽  
Water Vapour ◽  
Adsorption Process ◽  
Starch Granules ◽  
Gluten Free ◽  
First Order ◽  
Vapour Adsorption ◽  
Water Vapour Adsorption ◽  
Kinetics Of ◽  
Over Time

Abstract This study evaluated the kinetics of water vapour adsorption on the surface of starch molecules derived from wheat. The aim of the study was to determine an equation that would allow estimation of water content in tested material in any timepoint of the adsorption process aimed at settling a balance with the environment. An adsorption isotherm of water vapour on starch granules was drawn. The parameters of the Guggenheim, Anderson, and De Boer equation were determined by characterizing the tested product and adsorption process. The equation of kinetics of water vapour adsorption on the surface of starch was determined based on the Guggenheim, Anderson, and De Boer model describing the state of equilibrium and on the model of a first-order linear inert element describing the changes in water content over time.

Differential heat of water adsorption for montmorillonite, kaolinite and allophane

Clay Minerals ◽  
1989 ◽  
Vol 24 (3) ◽  
pp. 505-512 ◽  
Author(s):  
S. Iwata ◽  
F. Izumi ◽  
A. Tsukamoto
Keyword(s):  
Water Vapour ◽  
Water Adsorption ◽  
Adsorption Process ◽  
Dominant Role ◽  
Equilibrium Constants ◽  
Adsorbed Water ◽  
Differential Heat ◽  
Clay Surface ◽  
Vapour Adsorption ◽  
Water Vapour Adsorption

AbstractDifferential heat of water vapour adsorption for Cs+-saturated montmorillonite, kaolinite and allophane was measured over a low relative humidity range from 10−4 to 10−1. Two interactions (clay surface atom-water and counterion-water) are mainly involved in the water vapour adsorption process. To assess the affinity of water to the clay surface, the amounts of adsorbed water and the differential heat due to Cs+ were estimated from equilibrium constants in the gas phase reactions. It is tentatively concluded that (i) a dominant role of water adsorption due to the Cs+-water interaction in the adsorption process is evident only for montmorillonite; (ii) the affinity of water to the clay surface is strongest for allophane and weakest for montmorillonite.

scholarly journals Changes in the size of the apparent surface area and adsorption energy of the rye roots by low pH and the presence of aluminium ions induced

2016 ◽  
Vol 30 (3) ◽  
pp. 375-381 ◽  
Author(s):  
Alicja Szatanik-Kloc
Keyword(s):  
Surface Area ◽  
Water Vapour ◽  
Adsorption Energy ◽  
High Energy ◽  
Root Surface ◽  
Low Ph ◽  
Vapour Adsorption ◽  
Average Water ◽  
Water Vapour Adsorption ◽  
Adsorption Desorption

Abstract The plant reactions on Al-stress include i.a. change of the surface area of the roots, which in the physicochemistry of plants characterizes the transport of water and ions through the root. The object of this study is the specific surface area of the roots of plants which are tolerant to aluminium, such as rye. Plants of rye were grown in a nutrient solution for 14 days at pH 4.5 in the presence of Al3+ ions of concentration 10, 20, and 40 mg dm−3. The control plants were grown continuously at pH 7 or pH 4.5 without Al3+. The apparent surface area and adsorption energy of the plants roots were determined from water vapour adsorption – desorption data. The apparent surface area of roots growing in the aluminium was (with respect to control) statistically significantly lower. There were no statistically significant differences in the apparent surface area of the roots which grew in pH 7, pH 4.5 without Al3+. The average water vapour adsorption energy of the root surface, under stress conditions decreased. In the roots grown in the presence of Al+3, there was a slight decrease in high energy adsorption centres and an increase in the amount of low-energy centres.

Synthetic allophane from highconcentration solutions: nanoengineering of the porous solid

Clay Minerals ◽  
2002 ◽  
Vol 37 (3) ◽  
pp. 451-456 ◽  
Author(s):  
F. Ohashi ◽  
S.-I . Wada ◽  
M. Suzuki ◽  
M. Maeda ◽  
S. Tomura
Keyword(s):  
Water Vapour ◽  
Particle Diameter ◽  
Amorphous Structure ◽  
Water Vapour Pressure ◽  
Transmission Electron ◽  
Bet Specific Surface Area ◽  
Relative Water ◽  
Vapour Adsorption ◽  
Water Vapour Adsorption ◽  
Adsorption Desorption

AbstractThe amorphous aluminosilicate allophane was synthesized by rapid mixing of inorganic solutions with high initial concentrations (10 – 100 mmol/l) followed by hydrothermal treatment. X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed homogeneous products having a hollow spherical amorphous structure with a particle diameter of 3 – 5 nm. The amorphous products had a high BET specific surface area (490 – 552 m2/g) in comparison with natural allophane and had a narrow pore-size distribution (2 – 5 nm in diameter). The results of water vapour adsorption isotherm studies showed a gradual increase over the range of relative water vapour pressure of 0.6 – 0.9 and reached a maximum of ∼85 wt.%. The synthetic allophane shows promise as an adsorbent material because of its high adsorption-desorption capacity and its unique structure.

Water vapour adsorption on coal

Fuel ◽  
2011 ◽  
Vol 90 (5) ◽  
pp. 1892-1899 ◽  
Author(s):  
Martina Švábová ◽  
Zuzana Weishauptová ◽  
Oldřich Přibyl
Keyword(s):  
Water Vapour ◽  
Vapour Adsorption ◽  
Water Vapour Adsorption
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