Liquid‐phase capillary condensation and adsorption isothern

Miyahara, Minoru; Kato, Masahito; Okazaki, Morio

doi:10.1002/aic.690400913

Cited by 13 publications

(5 citation statements)

References 10 publications

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“…In the context of this paper the important concept is that of capillary condensation, or “capillary phase separation”, of the preferentially wetting phase of a binary mixture prior to two-phase coexistence in bulk. This pore-induced formation of a phase which is not stable in bulk is closely analogous to the formation of a stable liquid phase from undersaturated vapors and can be explained in similar terms (e.g., refs and ). Although we are primarily interested in condensation from mixed vapor s it should be noted that there are very close similarities between the two phenomena.…”

Section: Introductionmentioning

confidence: 69%

Capillary Condensation from Vapors of n-Hexane/Perfluoro-n-hexane Mixtures

Kohonen

Christenson

2002

J. Phys. Chem. B

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We have used a modified surface force apparatus to study capillary condensation of near-saturated vapors of n-hexane/perfluoro-n-hexane mixtures in a model pore formed by the gap between two mica surfaces. The measured compositions and mean meniscus radii of curvature of the capillary condensates are in broad agreement with the predictions of the binary Kelvin equations. Our results also show that n-hexane is preferentially adsorbed at the mica/liquid interface of the condensed mixtures, with the extent of adsorption depending on the position in the liquid-liquid phase diagram of the mixture. In addition, liquid-liquidphase separation was observed in condensates formed from vapors of bulk perfluoro-n-hexane-rich mixtures at, or very close to phase-coexistence. This results in the formation of novel two-phase or "double" condensates, consisting of an inner condensate of a n-hexane-rich phase within an outer condensate of perfluoro-n-hexanerich phase. Capillary condensation from vapors coexisting with phase-separated bulk mixtures gives rise to condensates of the n-hexane-rich phase. Finally, we have observed that the composition of a mixed condensate can show a significant time-dependence in the initial stages of condensation.

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Section: Introductionmentioning

confidence: 69%

Capillary Condensation from Vapors of n-Hexane/Perfluoro-n-hexane Mixtures

Kohonen

Christenson

2002

J. Phys. Chem. B

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“…The irreversibility of adsorption onto soils and humic acids has been attributed by several authors to micropore deformation at high concentration levels due to penetration of adsorbate molecules and entrapment when the solution concentration is abruptly decreased during desorption − . Hysteresis due to a capillary phase separation mechanism , may also occur in humic acid mesopores.…”

Section: Resultsmentioning

confidence: 99%

Adsorption−Desorption Behavior of Thiram onto Humic Acid

Filipe

Vidal

Duarte

et al. 2009

J. Agric. Food Chem.

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The adsorption/desorption behavior of pure thiram (Thi-P) and formulated thiram (Thi-F) onto commercial humic acids (HA) was studied using a batch equilibration procedure. Results of adsorption kinetic experiments showed that thiram adsorption is a fast process since 85% of the equilibrium concentration is reached within two hours. Experimental K(D) values between 0.110 to 0.210 L g(-1) were obtained for the adsorption of both Thi-P and Thi-F onto HA, suggesting that thiram is strongly sorbed by humic acids. In general, for both Thi-P and Thi-F, the lower the initial thiram concentration, the stronger is its adsorption (higher K(D) and percentage adsorption values). The adsorption isotherms were found to match the BET model. The results show that thiram adsorption onto condensed humic acids cannot be explained only in terms of specific interactions, such as those identified in studies of adsorption of thiram with humic acids in solution. The comparison of sorption and desorption results allowed the observation of hysteresis phenomena. Desorption K(D) values were consistently higher than those for adsorption at the same equilibrium concentration. Hysteresis was lower for the formulated thiram suggesting that adsorption is more reversible in the presence of the formulation components turning the pesticide more susceptible to be leached.

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“…Depending on the influence of the attractive potential energy of the pore walls, fluids in slit nanopores showed CPS at a concentration lower than the concentration predicted by Patrick and Miyahara et al (Patrick and Eberman 1925;Patrick and Jones 1925;Miyahara et al 1994Miyahara et al , 1997aMiyahara et al , 1997b). …”

Section: Introductionmentioning

confidence: 71%

“…This concept had been largely unnoticed until Miyahara et al experimentally studied it and proposed a similar concept model (Miyahara et al 1994(Miyahara et al , 1997a.…”

Section: Introductionmentioning

confidence: 99%

“…C denotes the concentration in the bulk phase; subscript s, the saturation; γ , the normal interfacial tension of two liquid phases; v B , the volume per molecule of the adsorbed liquid; W , the pore width; and t, the thickness of the liquid film adsorbed on the pore surface; this equation was introduced by Miyahara et al (Miyahara et al 1994(Miyahara et al , 1997a. In principle, the critical concentration of the CPS must be determined by only the pore size.…”

Section: Introductionmentioning

confidence: 99%

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Liquid-liquid phase separation of binary Lennard-Jones fluid in slit nanopores

Kanda

Makino

2008

Adsorption

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The capillary phase separation of a binary mixture of two truncated and shifted Lennard-Jones (LJ) Ar liquids in slit-shaped oxygen nanopores is examined. Thewere used to distinguish the two Ar liquids. The cut off distance for Ar was 3.5σ . We employed a molecular dynamics (MD) technique in which a pore space was connected with a bulk solution to easily determine the equilibrium bulk concentration. Liquid phase isotherms were obtained for pores with widths ranging from 5.5σ to 9.5σ, and the relation between the pore width and the phase separation concentration was determined. Each simulation was run until the bulk concentration attained equilibrium (1-2 μs). The MD results show that the Patrick model overestimates the bulk concentration for a given pore size. We proposed a modified Patrick model in which the pore wall potential is considered. In our model, the Gibbs-Tolman-Koenig-Buff effect is not considered for the interfacial tension since two surfaces of tension exist on both sides of the equimolar dividing surface of the two-Ar liquid phase. The two surfaces of tension neutralized Gibbs-Tolman-Koenig-Buff effect each other. The present simple model successfully describes the relation to prove its reliability.

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Liquid‐phase capillary condensation and adsorption isothern

Cited by 13 publications

References 10 publications

Capillary Condensation from Vapors of n-Hexane/Perfluoro-n-hexane Mixtures

Capillary Condensation from Vapors of n-Hexane/Perfluoro-n-hexane Mixtures

Adsorption−Desorption Behavior of Thiram onto Humic Acid

Liquid-liquid phase separation of binary Lennard-Jones fluid in slit nanopores

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