Area Occupied by a Water Molecule Adsorbed on Silica at 298 K: Zeta Adsorption Isotherm Approach

Narayanaswamy, Nagarajan; Ward, C. A.

doi:10.1021/acs.jpcc.9b11976

Cited by 7 publications

(29 citation statements)

References 65 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The best results were found using the lower values for ω 0 so that this parameter was fixed at 2.0 × 10 5 m 2 /mol. It can be mentioned here that this value is very close to the molar area of a layer of adsorbed water molecules on mica surfaces (≈1.8 × 10 5 m 2 /mol or ≈0.30 nm 2 /molecule) [64];…”

supporting

confidence: 71%

β-Lactoglobulin Adsorption Layers at the Water/Air Surface: 5. Adsorption Isotherm and Equation of State Revisited, Impact of pH

Gochev

Kovalchuk

Aksenenko

et al. 2021

Colloids and Interfaces

View full text Add to dashboard Cite

The theoretical description of the adsorption of proteins at liquid/fluid interfaces suffers from the inapplicability of classical formalisms, which soundly calls for the development of more complicated adsorption models. A Frumkin-type thermodynamic 2-d solution model that accounts for nonidealities of interface enthalpy and entropy was proposed about two decades ago and has been continuously developed in the course of comparisons with experimental data. In a previous paper we investigated the adsorption of the globular protein β-lactoglobulin at the water/air interface and used such a model to analyze the experimental isotherms of the surface pressure, Π(c), and the frequency-, f-, dependent surface dilational viscoelasticity modulus, E(c)f, in a wide range of protein concentrations, c, and at pH 7. However, the best fit between theory and experiment proposed in that paper appeared incompatible with new data on the surface excess, Γ, obtained from direct measurements with neutron reflectometry. Therefore, in this work, the same model is simultaneously applied to a larger set of experimental dependences, e.g., Π(c), Γ(c), E(Π)f, etc., with E-values measured strictly in the linear viscoelasticity regime. Despite this ambitious complication, a best global fit was elaborated using a single set of parameter values, which well describes all experimental dependencies, thus corroborating the validity of the chosen thermodynamic model. Furthermore, we applied the model in the same manner to experimental results obtained at pH 3 and pH 5 in order to explain the well-pronounced effect of pH on the interfacial behavior of β-lactoglobulin. The results revealed that the propensity of β-lactoglobulin globules to unfold upon adsorption and stretch at the interface decreases in the order pH 3 > pH 7 > pH 5, i.e., with decreasing protein net charge. Finally, we discuss advantages and limitations in the current state of the model.

show abstract

supporting

confidence: 71%

β-Lactoglobulin Adsorption Layers at the Water/Air Surface: 5. Adsorption Isotherm and Equation of State Revisited, Impact of pH

Gochev

Kovalchuk

Aksenenko

et al. 2021

Colloids and Interfaces

View full text Add to dashboard Cite

show abstract

“…At some sites, there would be ζ th molecules adsorbed, but at these sites as well, there would be one adsorbed vapor molecule from each of the adsorbed components at the M g adsorption sites. The area of the substrate, A s , would then be given by 18,20,24 A N M T T ( ) ( ) By using eq 16 with eq 27, one finds that the number of adsorption sites per unit area, M, is inversely proportional to the occupied area σ A…”

Section: Expressions For the Zeta Adsorption Isotherm Functionmentioning

confidence: 99%

“…Then, the latent heat of the adsorbate, Λ A SV , as a function of x V is determined from adsorbate heating 18,20 and is given by i k j j j j j j y…”

Section: Zeta Adsorption Isotherm Analysis Of Experimental Adsorption...mentioning

confidence: 99%

“…This was interpreted to indicate the presence of phase instabilities. 18,20 The data in the micropore range, x V < x μ3…”

Section: Zeta Adsorption Isotherm Analysis Of Experimental Adsorption...mentioning

confidence: 99%

“…When this assumption is imposed on calculations, it leads to a relation between the area of the adsorbed Ar atom, σ A (Ar, T), and an adsorbed N 2 molecule, σ A (N 2 , T). 20 When σ A (N 2 , T) is assigned a value of 0.162 nm 2 , as is often assumed, 21,22 the ZAI relation indicates that σ A (Ar, T) adsorbed on silica at 87 K is 0.182 ± 1% nm 2 . Others have used the same assumption, but they based their approach on the BET isotherm 10,23 and found that the result was unsatisfactory.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Specific Surface Area of Nanopowders from Argon Adsorption at 77 and 87 K: Zeta Adsorption Isotherm Approach

Narayanaswamy

Ward

2021

J. Phys. Chem. C

Self Cite

View full text Add to dashboard Cite

The surface characterization of nanopowders is widely attempted by both N2 and Ar vapor adsorption methods. They are used as complementary probe molecules because of their similarities and certain differences. However, the respective reported analyses, using the Brunauer–Emmett–Teller method, suffer from inconsistencies between the determined values of the specific surface areas, A s. We examine this issue by using the zeta adsorption isotherm approach on the reported data for both vapors on two different samples from the same batch of a nanopowder material. By assuming the equivalence of the A s determined by both of the vapors, we obtain the average occupied area of an adsorbed argon atom, σA(Ar), on silica and carbon black at the solid- and liquid-state temperatures of 77 and 87 K, respectively. We then examine the determined value of σA(Ar) by obtaining A s for other samples of the same material with varying specific areas. By transforming the adsorption data from mass-specific to area-specific, the respective thermodynamic isotherms, n SV, of Ar vapor adsorbing on silica and carbon black are obtained. The determined n SV are then used with the Gibbs adsorption equation to determine the solid surface energy, γS0, and solid–vapor interface energy, γSV, for both substrates. The obtained γSV(x V) on both substrates is used to interpret the phase transition state of the Ar adsorbate at 77 K. The determined thermodynamic isotherms for Ar and N2 vapors are further used in a comparative study to show that the Ar vapor adsorption is negligibly affected by the change in silanol concentration on the silica surface in contrast with N2 vapor adsorption.

show abstract

Surface Exospheric Interactions

et al. 2023

View full text Add to dashboard Cite

Gas-surface interactions at the Moon, Mercury and other massive planetary bodies constitute, alongside production and escape, an essential element of the physics of their gravitationally bound exospheres. From condensation and accumulation of exospheric species onto the surface in response to diurnal and seasonal changes of surface temperature, to thermal accommodation, diffusion and ultimate escape of these species from the regolith back into space, surface-interactions have a drastic impact on exospheric composition, structure and dynamics. The study of this interaction at planetary bodies combines exospheric modeling and observations with a consideration of fundamental physics and laboratory experimentation in surface science. With a growing body of earth-based and spacecraft observational data, and a renewed focus on lunar missions and exploration, the connection between the exospheres and surfaces of planetary bodies is an area of active and growing research, with advances being made on problems such as topographical and epiregolith thermal effects on volatile cold trapping, among others. In this paper we review current understanding, latest developments, outstanding issues and future directions on the topic of exosphere-surface interactions at the Moon, Mercury and elsewhere.

show abstract

Area Occupied by a Water Molecule Adsorbed on Silica at 298 K: Zeta Adsorption Isotherm Approach

Cited by 7 publications

References 65 publications

β-Lactoglobulin Adsorption Layers at the Water/Air Surface: 5. Adsorption Isotherm and Equation of State Revisited, Impact of pH

β-Lactoglobulin Adsorption Layers at the Water/Air Surface: 5. Adsorption Isotherm and Equation of State Revisited, Impact of pH

Specific Surface Area of Nanopowders from Argon Adsorption at 77 and 87 K: Zeta Adsorption Isotherm Approach

Surface Exospheric Interactions

Contact Info

Product

Resources

About