Bulk activity measurements of organic compounds in aqueous electrolyte solutions and their implication in electrosorption studies

Journal Article · Fri Jan 01 04:00:00 EST 1993 · Langmuir; (United States)

DOI:https://doi.org/10.1021/la00025a059· OSTI ID:6784302

Baikerikar, K G; Hansen, R S ^[1]

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1. Iowa State Univ., Ames (United States)

Bulk activity measurements of the slightly soluble aliphatic alcohols 1-butanol, 2-butanol, 1-pentanol, 3-methyl-1-butanol, and 1-hexanol in various aqueous electrolyte solutions were made using the gas chromatographic method of Mohilner et al. a[sub A], x[sub A], m[sub A], and f[sub A] are the alcohol activity, mole fraction, molality, and activity coefficient with f[sub A] defined by a[sub A] = f[sub A]x[sub A] and standard state defined by a[sub A] = 1 when x[sub A] = 1. Representation of data by lnf[sub A] = ln f[degrees][sub A]-k[prime][sub A]m[sub A] + k[double prime][sub A]m[sub A][sup 2], with k[prime][sub A] and k[double prime][sub A] adjustable parameters expected to depend on both alcohol and electrolyte, was investigated. Plots of lnf[sub A] vs m[sub A] were found to be linear within experimental error up to saturation value of m[sub A] in all cases investigated; i.e., the k[double prime][sub A]m[sub A][sup 2] contributed negligibly in all cases and concentrations investigated and could be omitted. Semiquantitative models, based on the principle of independent surface action (for water-alcohol interactions) and dependence of electrolyte activities on dielectric constant, were developed and found to provide reasonable qualitative and semiquantitative interpretation of parameter trends and basis for semiquantitative estimation of parameters for other similar systems. In electrosorption studies involving measurement of the dependence of interfacial tension on organic solute concentration at fixed polarization with respect to a fixed reference electrode (e.g., a saturated calomel electrode), the activity coefficients of both alcohol and electrolyte will change as the organic solute concentration changes. Bases for calculating these changes and their effect on the estimation of organic solute surface excess are given and discussed. 23 refs., 3 figs., 1 tab.

• OSTI ID: 6784302
• Journal Information: Langmuir; (United States), Journal Name: Langmuir; (United States) Vol. 9:1; ISSN LANGD5; ISSN 0743-7463
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALCOHOLS
AQUEOUS SOLUTIONS
BUTANOLS
CHROMATOGRAPHY
DIELECTRIC PROPERTIES
DISPERSIONS
ELECTRICAL PROPERTIES
ELECTROLYTES
GAS CHROMATOGRAPHY
HEXANOLS
HYDROXY COMPOUNDS
MIXTURES
ORGANIC COMPOUNDS
PENTANOLS
PHYSICAL PROPERTIES
SEPARATION PROCESSES
SOLUTIONS
SORPTIVE PROPERTIES
SURFACE PROPERTIES
THERMODYNAMIC ACTIVITY