Adsorption of volatile hydrophobic organic compounds at the vapor/water interface

Persistent Link:
http://hdl.handle.net/10150/191248
Title:
Adsorption of volatile hydrophobic organic compounds at the vapor/water interface
Author:
Bruant, Robert Gilbert.
Issue Date:
2000
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Aqueous solution surface tension as a function of vapor-phase solute pressure isotheims were measured at atmospheric pressure for single and binary component benzene, methyl-substituted benzene (i.e., methylbenzene, 1,2-dimethylbenzene, 1,3- dimethylbenzene, 1,4-dimethylbenzene, 1,3,5-trimethylbenzene), and trichloroethene adsorption. Solute-induced surface tension variations were quantified using a dynamic adsorption protocol in conjunction with Axisymmetric Drop Shape Analysis-Profile (ADSA-P) applied to pendant drop tensiometry. For single component adsorption, isotherms were measured at temperatures of 285.2K, 291.2 K, 297.2 K, 298.2 K, 303.2 K, and 315.2 K, for vapor-phase solute pressures ranging from zero to near/at saturated vapor pressure. For binary solute experiments, three intermediate constant vapor-phase mole ratio isotherms were developed for each solute pair (i.e., benzene and each of the five methyl-substituted benzenes) at temperatures of 285.2 K, 291.2 K, 298.2 K. Results for single component adsorption studies indicate that for a given vapor-phase solute pressure, interface-phase solute activity increases with molecular size (mass) among the benzene homologues. Similarly, compounds are more strongly adsorbed at the vapor/water interface as the system temperature decreases. Ideal standard free energy, enthalpy, and entropy changes of adsorption, calculated from limiting isotherm data, suggest specific solute-water interactions and a perturbation of the interface-phase water structure on adsorption. Further analysis of binary solute isotherms indicates that interface-mixing is well described by a two-dimensional application of Raoult's law, implying ideal interface-phase solute-solute interactions. Consideration of the twodimensional second virial coefficients suggests that interface-phase solute molecules engage in attractive interactions, with greater interactions for larger molecular sizes.
Type:
Dissertation-Reproduction (electronic); text
Keywords:
Hydrology.; Organic compounds -- Absorption and adsorption.; Surface tension.; Interfaces (Physical sciences)
Degree Name:
Ph. D.
Degree Level:
doctoral
Degree Program:
Hydrology and Water Resources; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Conklin, Martha H.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleAdsorption of volatile hydrophobic organic compounds at the vapor/water interfaceen_US
dc.creatorBruant, Robert Gilbert.en_US
dc.contributor.authorBruant, Robert Gilbert.en_US
dc.date.issued2000en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractAqueous solution surface tension as a function of vapor-phase solute pressure isotheims were measured at atmospheric pressure for single and binary component benzene, methyl-substituted benzene (i.e., methylbenzene, 1,2-dimethylbenzene, 1,3- dimethylbenzene, 1,4-dimethylbenzene, 1,3,5-trimethylbenzene), and trichloroethene adsorption. Solute-induced surface tension variations were quantified using a dynamic adsorption protocol in conjunction with Axisymmetric Drop Shape Analysis-Profile (ADSA-P) applied to pendant drop tensiometry. For single component adsorption, isotherms were measured at temperatures of 285.2K, 291.2 K, 297.2 K, 298.2 K, 303.2 K, and 315.2 K, for vapor-phase solute pressures ranging from zero to near/at saturated vapor pressure. For binary solute experiments, three intermediate constant vapor-phase mole ratio isotherms were developed for each solute pair (i.e., benzene and each of the five methyl-substituted benzenes) at temperatures of 285.2 K, 291.2 K, 298.2 K. Results for single component adsorption studies indicate that for a given vapor-phase solute pressure, interface-phase solute activity increases with molecular size (mass) among the benzene homologues. Similarly, compounds are more strongly adsorbed at the vapor/water interface as the system temperature decreases. Ideal standard free energy, enthalpy, and entropy changes of adsorption, calculated from limiting isotherm data, suggest specific solute-water interactions and a perturbation of the interface-phase water structure on adsorption. Further analysis of binary solute isotherms indicates that interface-mixing is well described by a two-dimensional application of Raoult's law, implying ideal interface-phase solute-solute interactions. Consideration of the twodimensional second virial coefficients suggests that interface-phase solute molecules engage in attractive interactions, with greater interactions for larger molecular sizes.en_US
dc.description.notehydrology collectionen_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.typetexten_US
dc.subjectHydrology.en_US
dc.subjectOrganic compounds -- Absorption and adsorption.en_US
dc.subjectSurface tension.en_US
dc.subjectInterfaces (Physical sciences)en_US
thesis.degree.namePh. D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineHydrology and Water Resourcesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairConklin, Martha H.en_US
dc.contributor.committeememberYeh, Tian-Chyi J.en_US
dc.contributor.committeememberRaghavan, Srinien_US
dc.contributor.committeememberFarrell, Jamesen_US
dc.contributor.committeememberEla, Wendell P.en_US
dc.identifier.oclc216935052en_US
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