Molecular modeling of sorption phenomena in environmental engineering

Persistent Link:
http://hdl.handle.net/10150/280483
Title:
Molecular modeling of sorption phenomena in environmental engineering
Author:
Luo, Jing
Issue Date:
2003
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:
This research investigated the adsorption mechanisms of hydrophobic chlorinated contaminants in mineral micropores and on iron metal surfaces. Activated adsorption and desorption of trichloroethylene (TCE) in mineral micropores was studied using experimental and molecular modeling techniques. Adsorption of TCE on a silica gel adsorbent was measured using a frontal analysis chromatography technique at atmospheric and elevated fluid pressures. The results showed that the increase in pressure was able to rapidly induce the formation of a desorption resistant fraction. Grand Canonical Monte Carlo (GCMC) modeling was used to elucidate the nature of water and TCE behavior within silica micropores. TCE adsorption was energetically most favorable in pores that were minimally large enough to accommodate one TCE molecule. A molecular level study of the interactions between hydrophobic chlorinated contaminants and sediments was performed. GCMC simulations were preformed to investigate water and TCE adsorption in slit micropores confined by charged and uncharged silica surfaces. Gas-phase single-sorbate simulations with water or TCE were performed as well as mixture simulations of bulk water containing TCE at 1% of its saturation concentration. Aqueous-phase TCE at a concentration equal to 1% of its saturation concentration was able to completely displace adsorbed water in uncharged pores. In highly hydrophilic pores, TCE at this concentration was able to displace up to 50% of the adsorbed water. Metallic iron filings are becoming increasingly utilized as reactive agents for reductive dechlorination of solvents in contaminated groundwaters. This research also used molecular modeling to study chemical adsorption of TCE and PCE to iron surfaces. Quantum mechanical calculations were performed to determine the thermodynamic favorability and resulting structures for chemical adsorption of TCE and PCE to iron surfaces. Molecular mechanics modeling was used to study the effects of atomic hydrogen on the thermodynamic favorability for chemically adsorbed TCE and PCE. Because TCE and PCE react with iron surfaces, their adsorption to iron cannot be investigated experimentally. This makes molecular modeling approaches a useful complement to experimental investigations of chemical reaction phenomena.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Engineering, Chemical.; Engineering, Civil.; Engineering, Environmental.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Chemical and Environmental Engineering
Degree Grantor:
University of Arizona
Advisor:
Farrell, James

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleMolecular modeling of sorption phenomena in environmental engineeringen_US
dc.creatorLuo, Jingen_US
dc.contributor.authorLuo, Jingen_US
dc.date.issued2003en_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.abstractThis research investigated the adsorption mechanisms of hydrophobic chlorinated contaminants in mineral micropores and on iron metal surfaces. Activated adsorption and desorption of trichloroethylene (TCE) in mineral micropores was studied using experimental and molecular modeling techniques. Adsorption of TCE on a silica gel adsorbent was measured using a frontal analysis chromatography technique at atmospheric and elevated fluid pressures. The results showed that the increase in pressure was able to rapidly induce the formation of a desorption resistant fraction. Grand Canonical Monte Carlo (GCMC) modeling was used to elucidate the nature of water and TCE behavior within silica micropores. TCE adsorption was energetically most favorable in pores that were minimally large enough to accommodate one TCE molecule. A molecular level study of the interactions between hydrophobic chlorinated contaminants and sediments was performed. GCMC simulations were preformed to investigate water and TCE adsorption in slit micropores confined by charged and uncharged silica surfaces. Gas-phase single-sorbate simulations with water or TCE were performed as well as mixture simulations of bulk water containing TCE at 1% of its saturation concentration. Aqueous-phase TCE at a concentration equal to 1% of its saturation concentration was able to completely displace adsorbed water in uncharged pores. In highly hydrophilic pores, TCE at this concentration was able to displace up to 50% of the adsorbed water. Metallic iron filings are becoming increasingly utilized as reactive agents for reductive dechlorination of solvents in contaminated groundwaters. This research also used molecular modeling to study chemical adsorption of TCE and PCE to iron surfaces. Quantum mechanical calculations were performed to determine the thermodynamic favorability and resulting structures for chemical adsorption of TCE and PCE to iron surfaces. Molecular mechanics modeling was used to study the effects of atomic hydrogen on the thermodynamic favorability for chemically adsorbed TCE and PCE. Because TCE and PCE react with iron surfaces, their adsorption to iron cannot be investigated experimentally. This makes molecular modeling approaches a useful complement to experimental investigations of chemical reaction phenomena.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectEngineering, Chemical.en_US
dc.subjectEngineering, Civil.en_US
dc.subjectEngineering, Environmental.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineChemical and Environmental Engineeringen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorFarrell, Jamesen_US
dc.identifier.proquest3119963en_US
dc.identifier.bibrecord.b45636916en_US
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