Soluble surface films of short-chain monocarboxylic acids on organic and aqueous substrates

Wright, E. H. M.; Akhtar, B. A.

doi:10.1039/j29700000151

Cited by 17 publications

(4 citation statements)

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“…The surface excesses were derived from measurements of surface tension reported in the literature for the alcohols, ,− carboxylic acids, ,, and carboxylates. , The uncertainty of the surface excess was estimated from the standard deviation of values derived from different studies. More details about the derivation of the surface excesses are given in the Supporting Information.…”

Section: Experimental Sectionmentioning

confidence: 99%

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Chemical Composition and Properties of the Liquid–Vapor Interface of Aqueous C1 to C4 Monofunctional Acid and Alcohol Solutions

et al. 2016

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The liquid-vapor interface is playing an important role in aerosol and cloud chemistry in cloud droplet activation by aerosol particles and potentially also in ice nucleation. We have employed the surface sensitive and chemically selective X-ray photoelectron spectroscopy (XPS) technique to examine the liquid-vapor interface for mixtures of water and small alcohols or small carboxylic acids (C1 to C4), abundant chemicals in the atmosphere in concentration ranges relevant for cloud chemistry or aerosol particles at the point of activation into a cloud droplet. A linear correlation was found between the headgroup carbon 1s core-level signal intensity and the surface excess derived from literature surface tension data with the offset being explained by the bulk contribution to the photoemission signal. The relative interfacial enhancement of the carboxylic acids over the carboxylates at the same bulk concentration was found to be highest (nearly 20) for propionic acid/propionate and still about 5 for formic acid/formate, also in fair agreement with surface tension measurements. This provides direct spectroscopic evidence for high carboxylic acid concentrations at aqueous solution-air interfaces that may be responsible for acid catalyzed chemistry under moderately acidic conditions with respect to their bulk aqueous phase acidity constant. By assessing the ratio of aliphatic to headgroup C 1s signal intensities XPS also provides information about the orientation of the molecules. The results indicate an increasing orientation of alcohols and neutral acids toward the surface normal as a function of chain length, along with increasing importance of lateral hydrophobic interactions at higher surface coverage. In turn, the carboxylate ions exhibit stronger orientation toward the surface normal than the corresponding neutral acids, likely caused by the stronger hydration of the charged headgroup.

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Section: Experimental Sectionmentioning

confidence: 99%

“…Derivation of Surface Excess. The surface excesses were derived from measurements of surface tension reported in the literature for the alcohols, 29,36−40 carboxylic acids, 29,41,42 and carboxylates. 43,44 The uncertainty of the surface excess was estimated from the standard deviation of values derived from different studies.…”

Section: ■ Introductionmentioning

confidence: 99%

Chemical Composition and Properties of the Liquid–Vapor Interface of Aqueous C1 to C4 Monofunctional Acid and Alcohol Solutions

et al. 2016

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“…Vapour-liquid equilibria of the butanoic acid + water binary mixture. The symbols represent the experimental data, and the continuous and the dashed curves the description SAFT-γ Mie approach with the four and five unlike induced association site schemes (described in the text), respectively: (a) isobaric temperature-mole fraction (T-x) phase diagram at pressures of P = 101.3 kPa (crosses), P = 79.99 kPa (diamonds), P = 53.33 kPa (triangles), P = 26.66 kPa (circles), and P = 13.33 kPa (squares) [21]; (b) isothermal pressuremole fraction (P-x) phase diagram at a temperature of T = 303.15 K [143]. Other than the vapour-liquid equilibrium at 13.33 and 101.3 kPa, the SAFT-γ Mie calculations are predictions.…”

Section: Resultsmentioning

confidence: 99%

“…The experimental vapour-liquid equilibrium data of the butanoic acid + water system [21,143] are compared with the description obtained with the SAFT-γ Mie approach in Figure 11. As can be seen from Figure 11, it is apparent that the SAFT-γ Mie provides a very good description of the fluid-phase equilibria of the butanoic acid + water mixture; the model incorporating an unlike induced association interaction mediated by five sites in the acid group if found to be in better agreement with experiment than the corresponding model incorporating four sites for the unlike association.…”

Section: Alkylcarboxylic Acid + Water Binary Mixturesmentioning

confidence: 99%

The development of unlike induced association-site models to study the phase behaviour of aqueous mixtures comprising acetone, alkanes and alkyl carboxylic acids with the SAFT-γ Mie group contribution methodology

Papaioannou

Dufal

Sadeqzadeh

et al. 2016

Fluid Phase Equilibria

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Providing accurate predictions of the thermodynamic properties of highly polar and hydrogen bonding compounds and their mixtures is challenging from a theoretical perspective. The combination of an equation of state (EoS) based on the statistical associating fluid theory (SAFT) with a group contribution (GC) methodology offers both accuracy and predictive capability for the thermodynamic properties of mixtures. In our current work, the SAFT-γ Mie equation of state is used to capture the underlying complexity of systems in which specific interactions (e.g., hydrogen bonding, dipolar interactions, chemical association) play an important role, by incorporating highly versatile association-site schemes to model mixtures in which unlike induced association interactions occur; this is done by assigning to the functional groups a number of association sites that are inactive in the pure fluid, but become active in certain mixtures. We refer to this type of association mechanism as "unlike induced" association and to the sites involved in this interaction as "unlike induced" association sites. The concept of unlike induced association sites is applied here to develop reliable SAFT-γ Mie group contribution models to describe the properties of acetone, alkyl carboxylic acids, and their mixtures with water and n-alkanes. The parameter table of available SAFT-γ Mie models is expanded to incorporate the corresponding group interaction parameters for acetone, which is treated as a molecular group, the carboxyl group COOH, and their unlike interaction group parameters with water, and the methyl CH 3 , methanediyl CH 2 , and methanetriyl CH alkyl groups. In particular, one unlike induced site is used with the acetone model to mediate hydrogen-bonding of the acetone oxygen in mixtures containing hydrogen-bond donors, and two pairs of unlike induced sites are included on the COOH group to mediate hydrogen-bond formation in mixtures of carboxylic acids and hydrogen-bond donors. The models developed allow for the successful description of the complex fluid-phase behaviour of the relevant binary and ternary mixtures, including accurate predictions of systems which have not been used to determine the model parameters.

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ChemInform Abstract: LOESLICHE OBERFLAECHENFILME VON KURZKETTIGEN MONOCARBONSAEUREN AUF ORGANISCHEN UND WAESSRIGEN SUBSTRATEN

Wright¹,

Akhtar²

1970

Chemischer Informationsdienst. Organische Chemie

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Soluble surface films of short-chain monocarboxylic acids on organic and aqueous substrates

Cited by 17 publications

References 0 publications

Chemical Composition and Properties of the Liquid–Vapor Interface of Aqueous C1 to C4 Monofunctional Acid and Alcohol Solutions

Chemical Composition and Properties of the Liquid–Vapor Interface of Aqueous C1 to C4 Monofunctional Acid and Alcohol Solutions

The development of unlike induced association-site models to study the phase behaviour of aqueous mixtures comprising acetone, alkanes and alkyl carboxylic acids with the SAFT-γ Mie group contribution methodology

ChemInform Abstract: LOESLICHE OBERFLAECHENFILME VON KURZKETTIGEN MONOCARBONSAEUREN AUF ORGANISCHEN UND WAESSRIGEN SUBSTRATEN

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