scholarly journals Direct Evidence for Curvature-Dependent Surface Tension in Capillary Condensation: Kelvin Equation at Molecular Scale

2018 ◽  
Vol 8 (4) ◽  
Author(s):  
Seongsoo Kim ◽  
Dohyun Kim ◽  
Jongwoo Kim ◽  
Sangmin An ◽  
Wonho Jhe
Keyword(s):  
Surface Tension ◽  
Direct Evidence ◽  
Capillary Condensation ◽  
Kelvin Equation ◽  
Molecular Scale

scholarly journals Revisiting Kelvin equation and Peng–Robinson equation of state for accurate modeling of hydrocarbon phase behavior in nano capillaries

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ilyas Al-Kindi ◽  
Tayfun Babadagli
Keyword(s):  
Experimental Data ◽  
Surface Tension ◽  
Equation Of State ◽  
Phase Behavior ◽  
Pore Radius ◽  
Microfluidic Chips ◽  
Tight Sandstone ◽  
Kelvin Equation ◽  
Rock Samples ◽  
Robinson Equation

AbstractThe thermodynamics of fluids in confined (capillary) media is different from the bulk conditions due to the effects of the surface tension, wettability, and pore radius as described by the classical Kelvin equation. This study provides experimental data showing the deviation of propane vapour pressures in capillary media from the bulk conditions. Comparisons were also made with the vapour pressures calculated by the Peng–Robinson equation-of-state (PR-EOS). While the propane vapour pressures measured using synthetic capillary medium models (Hele–Shaw cells and microfluidic chips) were comparable with those measured at bulk conditions, the measured vapour pressures in the rock samples (sandstone, limestone, tight sandstone, and shale) were 15% (on average) less than those modelled by PR-EOS.

scholarly journals The sorption of vapours by ferric oxide gel. I.―Aliphatic alcohols

1934 ◽  
Vol 147 (860) ◽  
pp. 128-140 ◽  
Keyword(s):  
Ethyl Alcohol ◽  
Ferric Oxide ◽  
Adsorption Process ◽  
Capillary Condensation ◽  
Adsorbed Layer ◽  
Adsorbed Molecule ◽  
Complete Agreement ◽  
Condensation Process ◽  
Kelvin Equation ◽  
The Difference

In this paper isothermals of a series of alcohols on ferric oxide gel at 25°C are described. The sorption of methyl, ethyl, n. and iso-propyl, and n. butyl alcohols has been investigated in order to determine how the nature of the isothermal alters with the size of the adsorbed molecule. Isothermals of benzene and ethyl alcohol on ferric oxide gel have been described previously, and an examination of these data leads to the conclusion that the hysteresis phenomena are associated with a capillary condensation process which follows a true adsorption process on the surface of the pores. The application of the Kelvin equation to the calculation of the capillary radii at corresponding volumes gives the values 16 and 18 A respectively, from the benzene and alcohol isothermals. The lack of complete agreement may, of course, be due to the fact that the limit of validity of the equation has been reached, but there remains a possibility that the difference actually arises from the variation in the thickness of the adsorbed layer with the size of the adsorbed molecules. A similar conclusion was arrived at from an examination of the isothermals of methyl and ethyl alcohol on a specimen of silica gel which exhibits hysteresis, and the present series has therefore been determined in order to provide more extensive data for testing the validity of the Kelvin equation.

scholarly journals Reminiscent capillarity in subnanopores

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Irena Deroche ◽  
T. Jean Daou ◽  
Cyril Picard ◽  
Benoit Coasne
Keyword(s):  
Surface Tension ◽  
Porous Materials ◽  
Adsorption Energy ◽  
Phenomenological Model ◽  
Chemical Potential ◽  
Nanoporous Materials ◽  
Simulation Data ◽  
Pore Sizes ◽  
Fluid Surface ◽  
Molecular Scale

Abstract Fluids in large and small pores display different behaviors with a crossover described through the concept of critical capillarity. Here we report experimental and simulation data for various siliceous zeolites and adsorbates that show unexpected reminiscent capillarity for such nanoporous materials. For pore sizes D exceeding the fluid molecule size, the filling pressures p are found to follow a generic behavior kBT ln p ∼ γ/ρD where γ and ρ are the fluid surface tension and density. This result is rationalized by showing that the filling chemical potential for such ultra-small pores is the sum of an adsorption energy and a capillary energy that remains meaningful even for severe confinements. A phenomenological model, based on Derjaguin’s formalism to bridge macroscopic and molecular theories for condensation in porous materials, is developed to account for the behavior of fluids confined down to the molecular scale from simple parameters.

New molecular scale insights into the α-transition of Nafion® thin films from variable temperature ATR-FTIR spectroscopy

2016 ◽  
Vol 18 (37) ◽  
pp. 26144-26150 ◽  
Author(s):  
V. Ozhukil Kollath ◽  
K. Karan
Keyword(s):  
Thin Films ◽  
Transition Temperature ◽  
Ir Spectroscopy ◽  
Ftir Spectroscopy ◽  
Long Range ◽  
Direct Evidence ◽  
Variable Temperature ◽  
Range Order ◽  
Long Range Order ◽  
Molecular Scale

IR spectroscopy based direct evidence of long range order–disorder in the Nafion backbone correlated with the α-transition temperature.

Adhesion of solids and the effect of surface films

1950 ◽  
Vol 202 (1069) ◽  
pp. 224-243 ◽  
Keyword(s):  
Surface Tension ◽  
Direct Evidence ◽  
Adsorbed Water ◽  
Solid Surfaces ◽  
Surface Films ◽  
Intimate Contact ◽  
Elastic Stresses ◽  
Lubricant Films ◽  
Surface Tension Forces ◽  
Effect Of Surface

Earlier experiments have shown that the friction between metals is due to the shearing of junctions formed by adhesion or welding at the points of intimate contact. This suggests that when the load is removed the junctions should remain and an appreciable normal force should be needed to separate the surfaces. Experiments show that with clean hard surfaces in dry air the adhesion is negligibly small. In moist air appreciable adhesion may be observed, and it is shown that this is due to the surface tension of a thin film of adsorbed water. The surface-tension forces due to thin films of liquid trapped between solid surfaces may be very large. Under certain conditions the viscosity of the liquid may also be important. The absence of adhesion between clean hard surfaces is not due to the non-formation of metallic junctions. Experiments show that it is due to the released elastic stresses which break the junctions one by one as the load is removed. With very soft metals, such as lead or indium, where the effect of released elastic stresses is very much less important, marked adhesion is observed in air, if the surfaces are freed of grosser contaminants. This adhesion provides direct evidence for the formation of metallic junctions by a process of cold welding or pressure welding at the points of Contact. If the surfaces are covered with oxide films of appreciable thickness, the amount of metallic interaction is diminished with a corresponding reduction in the adhesion. Lubricant films have a similar effect, and in general those materials which are most effective in reducing the adhesion are also most effective, as boundary lubricants, in reducing the friction.

Capillary Condensation Adhesion Phenomena and Analysis of the Micromechanical Gyroscope

2013 ◽  
Vol 562-565 ◽  
pp. 251-254
Author(s):  
Yun Li He ◽  
Hai Peng Liu ◽  
Shi Qiao Gao ◽  
Cai Feng Wang
Keyword(s):  
Liquid Bridge ◽  
Capillary Condensation ◽  
Micro Structure ◽  
Macroscopic System ◽  
Kelvin Equation ◽  
Capillary Adhesion ◽  
Micromechanical Gyroscope ◽  
Capillary Phenomenon

In MEMS, the size of micro-structure is usually in the micron and even nanoscale. It's easier to form capillary phenomenon than the macroscopic system. In view of this phenomenon, this article is based on the micro-mechanical gyroscope as the research object, to analyze the occurrence of capillary condensation of adhesion phenomenon. Firstly, we derive the Kelvin equation for capillary condensation, and then combination of the Kelvin equation introduce the capillary condensation of the adhesion phenomenon; Secondly, it analyzes the dynamics characteristics of its structure existing the liquid bridge, and analyzes the causes of the liquid bridge; Finally, it analyzes the capillary adhesion phenomena on the performance of the micro-mechanical gyroscope,as well as how to avoid the generation of capillary condensation adhesion.

Probing Surface Roughness and Porosity through Adsorption of Wetting Layers

1994 ◽  
Vol 366 ◽  
Author(s):  
J. Krim ◽  
V. Panella
Keyword(s):  
Surface Tension ◽  
Adsorption Isotherms ◽  
Capillary Condensation ◽  
Scanning Tunneling ◽  
Fractal Nature ◽  
Tunneling Microscopy ◽  
Gold Surfaces ◽  
X Ray ◽  
Adsorption Data ◽  
The Impact

ABSTRACTWe have employed a quartz microbalance technique to record adsorption isotherms on silver and gold surfaces whose roughness has also been characterized by x-ray reflectivity or scanning tunneling microscopy. We observe strikingly different behavior for two different liquid adsorbates (oxygen and nitrogen), and attribute this to a difference in their surface tension. Our results demonstrate the impact that capillary condensation phenomena can have on the interpretation of adsorption data, particularly with regards to the fractal nature of the substrate. Valuable information on surface morphology can nonetheless be obtained from adsorption isotherms, if combined with alternate experimental techniques.

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