THE EXCHANGE OF OXYGEN-18 BETWEEN CELLULOSE, ADSORBED WATER, AND WATER VAPOR

1959 ◽  
Vol 37 (11) ◽  
pp. 1829-1833 ◽  
Author(s):  
A. R. G. Lang ◽  
S. G. Mason
Keyword(s):  
Water Vapor ◽  
Adsorption Isotherm ◽  
Adsorbed Water ◽  
Regenerated Cellulose ◽  
Vapor Pressures ◽  
Dilution Technique

The adsorption on regenerated cellulose of water at vapor pressures of 0 to 40 μ Hg has been measured by an oxygen-18 dilution technique. The results showed that cellulose may be dried to less than 0.04% moisture by evacuation at 70 °C. The adsorption isotherm was compared with that of Taylor for viscose rayon.It was also shown that oxygen-18 does not exchange between cellulose and water.

Isotopic Exchange Between Hydrogen and Water Vapor over Supported Metal Catalysts. Part I. Kinetics of the Exchange

1972 ◽  
Vol 50 (12) ◽  
pp. 1900-1906 ◽  
Author(s):  
J. H. Rolston ◽  
J. W. Goodale
Keyword(s):  
Water Vapor ◽  
Transfer Rate ◽  
Water Vapor Pressure ◽  
Adsorbed Water ◽  
Deuterium Atom ◽  
Supported Metal Catalysts ◽  
Vapor Pressures ◽  
Order Dependence ◽  
Rate Limiting ◽  
Kinetics Of

Some rate data for the transfer of a deuterium atom tracer between hydrogen and water vapor, catalyzed by platinum supported on γ-alumina, are reported. Above 100 °C the transfer rate measured at 1 atm total pressure is shown to be free of mass transfer effects, and obeys an initial first order dependence on water vapor for vapor pressures less than 10 Torr. A near zero order dependence is observed at higher water vapor pressures. At temperatures below 100 °C the transfer rate is essentially independent of water vapor pressure between 5 and 100 Torr suggesting that surface adsorbed water is involved in the rate limiting transfer step.

THE HEAT OF WETTING OF SILK FIBROIN BY WATER

1955 ◽  
Vol 33 (5) ◽  
pp. 904-912 ◽  
Author(s):  
H. Brian Dunford ◽  
John L. Morrison
Keyword(s):  
Water Vapor ◽  
Adsorption Isotherm ◽  
Thermodynamic Properties ◽  
Silk Fibroin ◽  
Adsorption Process ◽  
Film Formation ◽  
Adsorbed Water ◽  
Water Vapor Adsorption ◽  
Free Energies ◽  
Heat Of Wetting

The heats of wetting by water of silk fibroin initially containing various amounts of adsorbed and desorbed water have been measured. These measurements along with the water vapor adsorption isotherm of Hutton and Gartside have been used to calculate the integral and differential heats, free energies, and entropies of adsorption. In contrast with cellulose, silk containing desorbed water evolves less heat than that containing adsorbed water. This fact suggests that any contribution by a heat of swelling term is very small for silk fibroin, so that the calculated thermodynamic properties probably can be assigned almost entirely to the adsorption process. The changes in the heats and entropies of adsorption appear to parallel the sequence of changes in film formation as revealed by surface area calculations.

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.

THE LOW PRESSURE DEHYDRATION OF MAGNESIUM SULPHATE HEPTAHYDRATE AND COBALTOUS CHLORIDE HEXAHYDRATE

1956 ◽  
Vol 34 (5) ◽  
pp. 591-599 ◽  
Author(s):  
R. W. Ford ◽  
G. B. Frost
Keyword(s):  
Water Vapor ◽  
Vapor Pressure ◽  
Magnesium Sulphate ◽  
Copper Sulphate ◽  
Water Vapor Pressure ◽  
Adsorbed Water ◽  
Vapor Pressures ◽  
Cobaltous Chloride ◽  
Chloride Hexahydrate ◽  
Initial Drop

Rates of dehydration under vacuum, and at a series of controlled water vapor pressures, have been carried out for powdered samples of magnesium sulphate heptahydrate and of cobaltous chloride hexahydrate. It has been found for the magnesium salt that as the pressures are increased, the rate at first drops rapidly, this decrease being followed by a period of acceleration which is followed in turn by a decline. The curves are similar to those previously reported for copper sulphate pentahydrate, but the changes occur over a much wider range of water vapor pressures. In the dehydration of cobaltous chloride hexahydrate the initial drop in rate with increase in water vapor pressure is not observed. The results are interpreted in terms of the crystallization of intermediate products in the presence of adsorbed water.

Thickness of the Still Air Layer Adhering to Perforated Plastic Plates and Fabric

1988 ◽  
Vol 58 (2) ◽  
pp. 86-90 ◽  
Author(s):  
Kozo Tsubouchi
Keyword(s):  
Water Vapor ◽  
Humidity Sensor ◽  
Unit Area ◽  
Water Vapor Pressure ◽  
Sample Surface ◽  
Hole Diameter ◽  
Vapor Pressures ◽  
Wide Range ◽  
Vapor Pressure Gradient ◽  
Surface Construction

The thickness of the still air layer adhering to perforated plastic plates and a fabric was investigated in terms of the water vapor pressure gradient in the zone of diffusion above the samples. The water vapor pressures above the samples were determined from measurements using a temperature and relative humidity sensor. To analyze the thickness of the still air layer for a wide range of evaporation rates, the hole diameter and the number of holes per unit area were changed and the measurements were under different temperature and humidity/gradient conditions. The thickness of the still air layer corresponded to a distance of 10 mm from the sample surface and was not related to the surface construction and materials.

scholarly journals Methods for Determining Mold Development and Condensation on the Surface of Building Barriers

Buildings ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 4 ◽  
Author(s):  
Aleksander Starakiewicz ◽  
Przemysław Miąsik ◽  
Joanna Krasoń ◽  
Lech Lichołai
Keyword(s):  
Water Vapor ◽  
Vapor Condensation ◽  
Mold Growth ◽  
Vapor Pressures ◽  
Climate Conditions ◽  
Outdoor Climate ◽  
Surface Condensation ◽  
Water Vapor Condensation ◽  
Calculation Results ◽  
Temperature Factors

The article presents four equivalent methods for checking mold growth on the surface of building barriers and checking water vapor condensation on their surface. Each method applies to two parallel phenomena that may occur on a building barrier. The first method is to calculate and compare temperature factors. In the second method, the characteristic humidity in the room is calculated and compared. The third method is to calculate and compare the characteristic temperatures in the room. The fourth method is based on the calculation and comparison of characteristic water vapor pressures. Three boundary conditions are presented for each method and phenomenon: when a given phenomenon can occur, when it begins or ends, and when it does not occur. The presented methods systematize the approach to the problem of mold development and surface condensation. The presented calculation results relate to the selected building barrier functioning in specific indoor and outdoor climate conditions. The calculation results confirm the compliance of the presented methods in identifying the phenomenon of mold growth or condensation on the surface of the barrier. A graphical interpretation of the results for each method with periods of occurrence or absence of a given phenomenon is also presented.

Preparation of matched reagents for use with the Scholander gas analyzer

1977 ◽  
Vol 43 (1) ◽  
pp. 164-166
Author(s):  
R. G. Collins ◽  
V. W. Musasche ◽  
E. T. Howley
Keyword(s):  
Water Vapor ◽  
Vapor Pressure ◽  
Volume Change ◽  
Quantitative Method ◽  
Gas Analysis ◽  
Vapor Pressures ◽  
Gas Analyzer ◽  
Atmospheric Air ◽  
Fixed Acid

Scholander's method of gas analysis requires that the solutions for CO2 absorber, O2 absorber, and acid-rinse be matched in terms of water vapor tension throughout the analysis. Any difference in vapor pressure between either or both of the absorbing solutions and the indicator drop (composed of acid-rinse) will produce a measurable volume change which cannot be attributed to the presence of absorbable gases. This paper describes a practical and quantitative method for preparing reagents whose vapor pressures are matched. A fixed acid-rinse formulation was used throughout. A CO2 absorber prepared from 1.35 N KOH and an O2 absorber prepared from 0.76 N KOH were both matched in terms of vapor pressure with Scholander's acid-rinse solution. Analysis of atmospheric air provided a check on the accuracy of the technique. The values obtained were O2 20.94%, CO2 0.03%, and N2 (balance) 79.04%.

scholarly journals Experimental Investigations on Some Synthetic Leucite Rocks under Water Vapor Pressures

1976 ◽  
Vol 52 (9) ◽  
pp. 469-472 ◽  
Author(s):  
Alok K. GUPTA ◽  
Kenzo YAGI ◽  
Yu HARIYA ◽  
Kosuke ONUMA
Keyword(s):  
Water Vapor ◽  
Experimental Investigations ◽  
Vapor Pressures

THERMODYNAMIC CHARACTERIZATION OF WATER ADSORBED ON PEAT

1977 ◽  
Vol 57 (4) ◽  
pp. 497-501 ◽  
Author(s):  
B. D. KAY ◽  
J. B. GOIT
Keyword(s):  
Heat Content ◽  
Adsorbed Water ◽  
Heat Of Fusion ◽  
Vapor Pressures ◽  
Thermodynamic Characterization ◽  
Dry Conditions ◽  
Adsorption Of Water ◽  
Adsorption On Heterogeneous Surfaces ◽  
Water Contents

A preliminary thermodynamic characterization of water adsorbed on peat of sphagnum origin has been completed. The characterization has indicated that this organic material has a reactivity with respect to water which is similar to that of a montmorillonite clay. Under the relatively dry conditions of this study, less water was adsorbed by samples with a very low rubbed fibre content. The relative partial molar heat content of the adsorbed water approached the latent heat of fusion at water contents of about 16%. Additional measurements are required in the range of relative vapor pressures of 0.0–0.5 in order to determine if Halsey’s theory for adsorption on heterogeneous surfaces is applicable to the adsorption of water on peat.

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