Sorption Kinetics of High Pressure Gases in Polymeric Tubing Materials

2006 ◽  
Author(s):  
P. Jaeger ◽  
S. Buchner ◽  
R. Eggers
Keyword(s):  
Diffusion Coefficients ◽  
Gas Permeability ◽  
Gravimetric Method ◽  
Sorption Kinetics ◽  
Operating Pressure ◽  
Gas Solubility ◽  
Atmospheric Conditions ◽  
High Solubility ◽  
Industrial Practice ◽  
Kinetics Of

A gravimetric method was applied to determine the sorption kinetics of gases into polymers. Diffusivity as well as sorption capacity are determined directly. Data of gas permeability that are required for calculating leakage rates in polymeric flexile gas and oil ducts may be retrieved by multiplying the obtained diffusion coefficients and the gas solubility. In general carbon dioxide enters polymers to the highest extent. In industrial practice, the high solubility of CO2 e.g. may lead to explosive decompression of sealings once the operating pressure is reduced to atmospheric conditions. Diffusion coefficients are presented in the range of 75 to 130°C at 2 to 30 MPa.

Alteration of the unsteady sorption behaviour of maple (Acer pseudoplatanus L.) and spruce (Picea abies (L.) Karst.) due to thermal modification

Holzforschung ◽  
2010 ◽  
Vol 64 (2) ◽  
Author(s):  
Alexander Pfriem ◽  
Mario Zauer ◽  
André Wagenführ
Keyword(s):  
Picea Abies ◽  
Water Vapour ◽  
Diffusion Coefficients ◽  
Gravimetric Method ◽  
Sorption Process ◽  
Thermal Modification ◽  
Acer Pseudoplatanus ◽  
Sorption Behaviour ◽  
Transport Behaviour ◽  
Kinetics Of

Abstract The aim of the present investigation was to evaluate the influence of a thermal modification on the kinetics of the water vapour sorption of maple (Acer pseudoplatanus L.) and spruce [Picea abies (L.) Karst.] based on the assumption that the Fickian equation can be applied in this regard in the first approximation. The unsteady-state sorption process between two equilibria of humidity was modelled as a diffusion process. The rate of sorption was recorded by the gravimetric method, and then the diffusion coefficient was determined through inverse parameter identification. The thermal modification leads to an alteration of the unsteady sorption behaviour of both wood species. Transport of water vapour decreases with increasing degree of modification. Depending on wood moisture, the trends of diffusion coefficients include all three levels of modification. Furthermore, the diffusion coefficients decrease when the thickness of specimens decreases. The calculated diffusion coefficients showed a length dependency both for unmodified and thermally modified spruce and maple. Accordingly, the results clearly show that these woods have a non-Fickian moisture transport behaviour. The results are nevertheless useful for comparative purposes.

Sorption kinetics of cesium on hydrous titanium dioxide

2003 ◽  
Vol 91 (10) ◽  
Author(s):  
Y. Altaş ◽  
H. Tel ◽  
G. Yaprak
Keyword(s):  
Titanium Dioxide ◽  
Ion Exchange ◽  
Exchange Rates ◽  
Diffusion Coefficients ◽  
Isotopic Exchange ◽  
Sorption Kinetics ◽  
Cesium Ions ◽  
Ion Exchange Reaction ◽  
Titanium Dioxides ◽  
Kinetics Of

SummaryTwo types of hydrous titanium dioxide possessing different surface properties were prepared and characterized to study the sorption kinetics of cesium. The effect of pH on the adsorption capacity were determined in both type sorbents and the maximum adsorption percentage of cesium were observed at pH 12. To elucidate the kinetics of ion-exchange reaction on hydrous titanium dioxide, the isotopic exchange rates of cesium ions between hydrous titanium dioxides and aqueous solutions were measured radiochemically and compared with each other. The diffusion coefficients of Cs

Modeling of sorption kinetics of U(VI) micro-quantities nanostructured materials with anatase mesoporous structures

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Veniamin Zheleznov ◽  
Aleksey Golikov ◽  
Tatiana Sokolnitskaya ◽  
Sergey Ivannikov
Keyword(s):  
Nanostructured Materials ◽  
Sorption Kinetics ◽  
Uranyl Ion ◽  
Competitive Sorption ◽  
Hydroxyl Groups ◽  
Complex Ions ◽  
The Stability ◽  
Kinetics Of ◽  
Mesoporous Structures ◽  
Ionic Forms

Abstract The sorption kinetics of uranyl ions micro-quantities from fluoride solutions by nanostructured materials with anatase mesoporous structures has been studied. Using the model of competitive sorption of ions and positively charged complexes of uranyl ion on deprotonated hydroxyl groups of an anatase, kinetic curves of changes in the ratio of ionic forms of uranium in solution were calculated. Modeling was carried out under the assumption of a two-stage mechanism of uranium complex ions sorption. The modeling considered the influence of the uranyl ion carbonate complexes formation. The shift in equilibrium among ionic forms of uranyl correlates with the stability of the complexes in solution.

In vivo assessment of human vaginal oxygen and carbon dioxide levels during and post menses

2005 ◽  
Vol 99 (4) ◽  
pp. 1582-1591 ◽  
Author(s):  
Donna R. Hill ◽  
Marianne E. Brunner ◽  
Deborah C. Schmitz ◽  
Catherine C. Davis ◽  
Janine A. Flood ◽  
...  
Keyword(s):  
Animal Studies ◽  
Pathogenic Bacteria ◽  
Sensor Technology ◽  
Atmospheric Conditions ◽  
Bacterial Virulence Factor ◽  
Carbon Dioxide Levels ◽  
Kinetics Of ◽  
Insertion Process

Previous in vitro and in vivo animal studies showed that O2and CO2concentrations can affect virulence of pathogenic bacteria such as Staphylococcus aureus. The objective of this work was to measure O2and CO2levels in the vaginal environment during tampon wear using newly available sensor technology. Measurements by two vaginal sensors showed a decrease in vaginal O2levels after tampon insertion. These decreases were independent of the type of tampons used and the time of measurement (mid-cycle or during menstruation). These results are not in agreement with a previous study that concluded that oxygenation of the vaginal environment during tampon use occurred via delivery of a bolus of O2during the insertion process. Our measurements of gas levels in menses showed the presence of both O2and CO2in menses. The tampons inserted into the vagina contained O2and CO2levels consistent with atmospheric conditions. Over time during tampon use, levels of O2in the tampon decreased and levels of CO2increased. Tampon absorbent capacity, menses loading, and wear time influenced the kinetics of these changes. Colonization with S. aureus had no effect on the gas profiles during menstruation. Taken collectively, these findings have important implications on the current understanding of gaseous changes in the vaginal environment during menstruation and the potential role(s) they may play in affecting bacterial virulence factor production.

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