scholarly journals Direct calculation of the dimerization constant of water molecules for a dense water vapor

2015 ◽  
pp. 66-71
Author(s):  
L.A. Bulavin ◽  
◽  
P.V. Makhlaichuk ◽  
S.V. Khrapatiy ◽  
◽  
...  
Keyword(s):  
Water Vapor ◽  
Direct Calculation ◽  
Water Molecules ◽  
Dimerization Constant ◽  
Dense Water

scholarly journals The Impact of the Electric Field on Surface Condensation of Water Vapor: Insight from Molecular Dynamics Simulation

Nanomaterials ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 64 ◽  
Author(s):  
Qin Wang ◽  
Hui Xie ◽  
Zhiming Hu ◽  
Chao Liu
Keyword(s):  
Molecular Dynamics ◽  
Water Vapor ◽  
Electric Field ◽  
Intermolecular Forces ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Attraction Force ◽  
Condensation Rate ◽  
Shape Transformation ◽  
The Impact

In this study, molecular dynamics simulations were carried out to study the coupling effect of electric field strength and surface wettability on the condensation process of water vapor. Our results show that an electric field can rotate water molecules upward and restrict condensation. Formed clusters are stretched to become columns above the threshold strength of the field, causing the condensation rate to drop quickly. The enhancement of surface attraction force boosts the rearrangement of water molecules adjacent to the surface and exaggerates the threshold value for shape transformation. In addition, the contact area between clusters and the surface increases with increasing amounts of surface attraction force, which raises the condensation efficiency. Thus, the condensation rate of water vapor on a surface under an electric field is determined by competition between intermolecular forces from the electric field and the surface.

scholarly journals The Effect of Extraction Conditions on the Barrier and Mechanical Properties of Kefiran Films

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 602
Author(s):  
Carmen Rodica Pop ◽  
Teodora Emilia Coldea ◽  
Liana Claudia Salanţă ◽  
Alina Lăcrămioara Nistor ◽  
Andrei Borşa ◽  
...  
Keyword(s):  
Water Vapor ◽  
Conformational Changes ◽  
Water Vapor Permeability ◽  
Edible Films ◽  
Film Structure ◽  
Water Soluble ◽  
Vapor Permeability ◽  
Water Molecules ◽  
Compact Structure ◽  
Technology Applications

Kefiran is an exopolysaccharide classified as a heteropolysaccharide comprising glucose and galactose in equimolar quantities, and it is classified as a water-soluble glucogalactan. This work aimed to investigate the effect of different extraction conditions of kefiran on the structural and physical properties of the edible films obtained. Fourier-transform infrared spectroscopy and scanning electron microscopy were performed, together with a determinations of moisture content, solubility, water vapor permeability and degree of swelling. The kefiran films presented values of the water vapor permeability between 0.93 and 4.38 × 10−11 g/m.s.Pa. These results can be attributed to the development of a more compact structure, where glycerol had no power to increase the free volume and the water vapor diffusion through their structure. The possible conformational changes in the kefiran film structure, due to the interspersing of the plasticizers and water molecules that they absorb, could be the reason for producing flexible kefiran films in the case of using glycerol as a plasticizer at 7.5% w/w. Moreover, it was observed that the extraction conditions are a significant factor in the properties of these films and their food technology applications.

scholarly journals Ein Wasserstoffisotopieeffekt im CuSO4 * 5H2O

1969 ◽  
Vol 24 (10) ◽  
pp. 1502-1511
Author(s):  
Karl Heinzinger
Keyword(s):  
Water Vapor ◽  
Aqueous Solutions ◽  
Separation Factor ◽  
Room Temperature ◽  
Copper Ion ◽  
Hydrogen Isotopes ◽  
Bulk Water ◽  
Water Molecules ◽  
Hydration Water ◽  
Sulfate Solutions

Abstract There are two kinds of water in CuSO4·5H2O differing by their binding in the crystal. The oxygen of four water molecules is bonded to the copper ion, that of the fifth molecule is hydrogen bonded. It is shown that the D/H ratios of these two kinds of water differ by 5.7%, the light isotope being enriched in the water molecules coordinated with the copper ion. The results show that there is no exchange of the hydrogen isotopes during the time needed for dehydration at room temperature which takes several days. The assumption has been confirmed that the water coordinated with the copper ion leaves the crystal first on dehydration at temperatures below 50 °C. Additional measurements of the separation factor for the hydrogen isotopes between water vapor and copper sulfate solutions allow conclusions on the fractionation of the hydrogen isotopes between bulk water and hydration water in aqueous solutions.

The hydrogen bonding structure of adsorbed water on silver iodide and Feldspar minerals

2020 ◽  
Author(s):  
Markus Ammann ◽  
Huanyu Yang ◽  
Luca Artiglia ◽  
Anthony Boucly
Keyword(s):  
Hydrogen Bonding ◽  
Water Vapor ◽  
Silver Iodide ◽  
Adsorbed Water ◽  
Photoelectron Spectra ◽  
Water Molecules ◽  
Xps Spectra ◽  
X Ray ◽  
Bonding Structure ◽  
Electron Yield

<p>The hydrogen bonding structure of adsorbed water on a solid substrate may control deposition nucleation, which is a pathway of heterogeneous ice nucleation. Hydrogen bonding of water molecules is also controlling the interface between the solid and liquid water relevant for other heterogeneous freezing modes. The hydrogen bonding structure may be affected by short and long-range interactions between the substrate and the water molecules nearby. Electron yield near edge X-ray absorption fine structure (NEXAFS) spectroscopy at the oxygen K-edge is used to experimentally explore the difference between the hydrogen bonding structure of interfacial H<sub>2</sub>O molecules under different conditions of temperature and water vapor pressure. Experiments reported in this work were performed at the in-situ electron spectroscopy endstation at the ISS beamline at the Swiss Light Source (PSI, SLS). We report electron yield oxygen K-edge NEXAFS spectra and X-ray photoelectron spectra from silver iodide (AgI) particles and milled feldspar samples exposed to water vapor at high relative humidity, but subsaturated with respect to ice. AgI serves as a well-studied reference case; and it contains no oxygen in its lattice, which simplifies the analysis of NEXAFS spectra at the O K-edge. The feldspar samples include a potassium containing microcline and a sodium-rich albite. The analysis of the NEXAFS spectra indicate rather tetrahedrally coordinated adsorbed water molecules on AgI particles. On the feldspars, the mobility of ions, as directly observed by the XPS spectra appears to have a strong impact on the hydrogen bonding structure, as apparent from substantial differences between samples previously immersed in pure water or as prepared. To sum up, we attempt to understand the behavior of the hydrogen bonding structure, which provides rich information about the arrangement of water molecules in the vicinity of a solid surface, that is linked to the ability of the solid to induce ice formation.</p>

Simultaneous diode laser based in situ quantification of oxygen, carbon monoxide, water vapor, and liquid water in a dense water mist environment

2007 ◽  
Vol 31 (1) ◽  
pp. 799-806 ◽  
Author(s):  
Andrew R. Awtry ◽  
Brian T. Fisher ◽  
Robert A. Moffatt ◽  
Volker Ebert ◽  
James W. Fleming
Keyword(s):  
Carbon Monoxide ◽  
Water Vapor ◽  
Diode Laser ◽  
Liquid Water ◽  
Water Mist ◽  
Dense Water

scholarly journals Study of Hydrophilic Properties of Polysaccharides

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Michael Ioelovich
Keyword(s):  
Water Vapor ◽  
Structural Characteristics ◽  
Sorption Isotherms ◽  
Water Vapor Sorption ◽  
Water Molecules ◽  
Vapor Sorption ◽  
Direct Proportion ◽  
Polar Groups ◽  
Sorption Of Water Vapor ◽  
Chitin And Chitosan

In this research, the structural characteristics, specific surface area, sorption of water vapor, and wetting enthalpy of various polysaccharides (cellulose, hemicelluloses, starch, pectin, chitin, and chitosan) have been studied. It was confirmed that crystallites are inaccessible for water, and therefore water molecules can interact only with polar groups in noncrystalline (amorphous) domains of biopolymers. The isotherms of water vapor sorption for various polysaccharides had sigmoid shapes, which can be explained by the absorption of water molecules in heterogeneous amorphous domains having clusters with different packing densities. The method of contributions of polar groups to sorption of water molecules was used, which allowed to derivate a simple calculating equation to describe the shape of sorption isotherms. The wetting of biopolymers with water was accompanied by a high exothermic thermal effect, in direct proportion to the amorphicity degree. The sorption values and wetting enthalpies of amorphous domains of biopolymers were calculated, which allowed to find the hydrophilicity index and compare the hydrophilicity of the various polysaccharides.

Adsorption Isotherm and Kinetics of Water Vapor Adsorption Using Novel Super-Porous Hydrogel Composites

2020 ◽  
Author(s):  
Hemant Mittal ◽  
Ali Al-Alili ◽  
Saeed M. Alhassan
Keyword(s):  
Water Vapor ◽  
Adsorption Isotherm ◽  
Adsorption Capacity ◽  
Polymer Matrix ◽  
Adsorbed Water ◽  
Water Vapor Adsorption ◽  
Water Molecules ◽  
Vapor Adsorption ◽  
Highly Effective ◽  
Desiccant Material

Abstract Deliquescent salts have high water vapor adsorption capacity, but they dissolve in water by forming crystalline hydrates. That restricts their use in different water vapor adsorption applications. However, this limitation can be overcome by incorporating deliquescent salts within a polymer matrix which will keep the salt solution in place. Furthermore, if the polymer matrix used is also capable of adsorbing water vapor, it will further improve the overall performance of desiccant system. Therefore, in this work, we are proposing the synthesis and use of a highly effective new solid polymer desiccant material, i.e. superporous hydrogel (SPHs) of poly(sodium acrylate-co-acrylic acid (P(SA-co-AA)), and subsequently its composite with deliquescent salt, i.e. calcium chloride (CaCl2), to adsorb water vapors from humid air without the dissolution of the salt in the adsorbed water. Parental PAA-SPHs matrix alone exhibited an adsorption capacity of 1.02 gw/gads which increased to 3.35 gw/gads after incorporating CaCl2 salt in the polymer matrix. Both materials exhibited type-III adsorption isotherm and the experimental isotherm data fitted to the Guggenheim, Anderson and Boer (GAB) isotherm model. However, the adsorption kinetics followed linear driving force model which suggested that this extremely high adsorption capacity was due to the diffusion of water molecules into the interconnected pores of SPHs via capillary channels followed by the attachment of adsorbed water molecules to the CaCl2 salt present in the polymer matrix. Furthermore, the adsorbents were used successively for six cycles of adsorption with a very little loss in adsorption capacity. Therefore, the proposed polymer desiccant material overcomes the problem of dissolution of deliquescent salts and opens the doors for a new class of highly effective solid desiccant material.

Molecular Origin of Fast Evaporation at the Solid–water–vapor Line in a Sessile Droplet

Nanoscale ◽  
2022 ◽  
Author(s):  
Yongfeng Huang ◽  
Cui Zhang ◽  
Sheng Meng
Keyword(s):  
Water Vapor ◽  
Contact Line ◽  
Water Molecules ◽  
Sessile Droplet ◽  
Vapor Line ◽  
Molecular Origin ◽  
Solid Water

By analyzing the behaviors of water molecules at the solid–water–vapor contact line, we explore the molecular origins of large evaporation rates at the contact line and find new ways to...

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