Surface Thermodynamics for Hydrocarbons on Wyodak Coals

and, Amy S. Glass; Stevenson, Damon S.

doi:10.1021/ef950224g

Cited by 3 publications

(13 citation statements)

References 41 publications

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“…A considerable amount of work has been done on the solvent swelling of coals, which has given rise to similar hypotheses of solvent-induced conformational flexibility in these macromolecular networks (Brenner 1984;Larsen and Mohammadi 1990;Glass and Stevenson 1996;Glass and Wenger 1998). The fewer reports on the solvent swelling behaviour of peats and soil organic matter have generally yielded similar support to the hypothesis of conformational flexibility (Chen and Schnitzer 1989;Lyon and Rhodes 1993;Lyon 1995).…”

Section: Evidence In Support Of Structural Flexibility In Complex Orgmentioning

confidence: 96%

Flexible conformation in organic matter coatings: An hypothesis about soil water repellency

Roy¹,

McGill²

2000

Can. J. Soil. Sci.

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Flexible conformation in organic matter coatings: An hypothesis about soil water repellency. Can. J. Soil Sci. 80: 143-152. Some soils develop severe water repellency several years or decades following oil contamination. We previously reported that soil water repellency is completely eliminated by extraction with amphiphilic solvents, but barely reduced by extraction with nonpolar solvents. We report here on solvent-induced reversible soil water repellency. Our results indicate that: (i) water repellency is completely eliminated following extraction with amphiphilic solvent, but partially restored following subsequent exposure to nonpolar, non-H-bonding solvent; (ii) extraction with nonpolar, non-H-bonding solvent generates water repellency in readily wettable control wettable soils, but not in pristine wettable soils, and (iii) repeated sequential extractions alternating between amphiphilic and nonpolar, non-H-bonding solvent increase extractable material and reduce the magnitude of solvent-induced soil water repellency with time.We attribute reversible soil water repellency to solvent-induced changes in the conformation of causative agents of soil water repellency. Recent literature reports on the structural flexibility of "insoluble" organic macromolecules are discussed for supporting evidence. We propose that exposure to nonpolar, non-H-bonding solvents induces stretching of surface-exposed, nonpolar moieties (i.e. alkyl chains), whereas exposure to polar, H-bonding solvents induces their coiling. These solvent-induced conformational changes are retained upon solvent removal. Our results indicate that the wettability of oil-contaminated soils depends on both the interfacial conformation and the fractional coverage of their surface-exposed nonpolar moieties. Certains sols acquièrent une grave imperméabilisation à l'eau plusieurs années, voire des décennies, après une contamination par le pétrole. Dans une précédente communication, nous signalions que l'imperméabilité à l'eau est complètement éliminée par extraction au moyen de solvants amphiphiles, mais qu'elle est à peine diminuée en présence de solvants non polaires. Nous traitons ici de l'imperméabilité réversible induite par des solvants. Il ressort de nos observations que i) ce type d'imperméabilité est éliminé complètement après extraction au moyen de solvants amphiphiles, mais qu'il est rétabli partiellement après exposition subséquente à un solvant non polaire sans liaison hydrogène, ii) l'extraction par un solvant de ce type provoque l'imperméabilité dans les sols contaminés témoins à mouillage facile, mais pas dans les sols mouillables non contaminés et iii) ces extractions séquentielles répétées, utilisant en alternance un solvant amphilile et un solvant sans liaison hydrogène non polaire produisent davantage de matériel extractible et réduisent à terme l'importance de l'hydrophobicité du sol due au solvant. Cette réversibilité de l'hydrophobicité du sol est attribuée au changement solvanto-induit de conformation des agents causaux de l'hydrophobic...

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Section: Evidence In Support Of Structural Flexibility In Complex Orgmentioning

confidence: 96%

Flexible conformation in organic matter coatings: An hypothesis about soil water repellency

Roy¹,

McGill²

2000

Can. J. Soil. Sci.

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“… a Adsorbate electronic volume polarizabilities calculated from α‘ 0 = {(3 M /ρ N )[( n 2 − 1)/( n 2 + 2)]}/4π, where M is the adsorbate molecular weight, ρ is the density, N is Avogadro's number, and n is the refractive index using densities and refractive indices from ref . b Datum for HF−HCl demineralized Wyodak coal heated at 225 °C …”

Section: Resultsmentioning

confidence: 99%

“…Figures and are plots of isosteric adsorption enthalpy vs adsorbate electronic volume polarizability for n -alkanes, 1-alkenes, benzene, and polar adsorbates on CAW and on CAW + Alk Wyodak coals, respectively …”

Section: Resultsmentioning

confidence: 99%

“…Since how well a molecule's electron cloud can be distorted (i.e., its polarizability) is a property of the entire molecule, the nonspecific dispersion interaction is a “whole-molecule” property. Nonspecific dispersion forces at coal surfaces are probed by nonpolar adsorbates such as saturated hydrocarbon ( n -alkane) adsorbates since then only the nonspecific force is measured. , For a given class of adsorbate molecule, the nonspecific dispersion force at a surface is proportional to any property which characterizes the overall electron distribution of the adsorbate molecule, e.g., molecular size or adsorbate polarizability . The polarizability is determined from the molecule's refractive index ( n ) or permittivity (ε)…”

Section: Theoretical Sectionmentioning

confidence: 99%

“…The data for polar adsorbates with this coal provide information about the nature of its nonspecific as well as its specific surface forces. Previous data that were presented for nonpolar (alkane and alkene) adsorbates provided information for its nonspecific and ionic forces . The data for polar molecules provide information which is important for a low-rank subbituminous coal such as Wyodak which possesses a relatively high percentage of polar functional groups (8% carbonyl, 8% phenolic) .…”

Section: Introductionmentioning

confidence: 99%

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Surface Thermodynamics for Polar Adsorbates on Wyodak Coals

Glass

Wenger

1998

Energy Fuels

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Adsorption enthalpies have been measured for polar molecules interacting with Wyodak coal. All of the polar adsorbates studied, including organic bases and 1-propanol, interact more strongly than predicted based on a model that includes van der Waals forces only. After the van der Waals component is subtracted from the total adsorption heat, the specific adsorption heat for each polar molecule on Wyodak coal is ∼1-4 kcal/mol more exothermic than its value on Illinois No. 6 coal. On alkylated Wyodak coal, the adsorption heats for organic bases are ∼1-3 kcal/mol as well. The adsorption heats for organic bases on alkylated Wyodak coal decrease in exothermicity by g5.0 kcal/mol, an amount that is similar to the specific hydrogen-bond interaction for each base with Illinois No. 6 coal. In contrast, 1-propanol's adsorption heat decreases by only ∼2 kcal/mol after alkylating the coal and 1-propanol's specific adsorption heat on alkylated Wyodak coal (6.8 kcal/mol) is the same as its specific adsorption heat on Illinois No. 6 coal. These results demonstrate that in addition to the van der Waals force, polar molecules experience two other forces on Wyodak coal, a ∼1-3 kcal/mol nonspecific dipole-induced dipole force and a g5.0 kcal/mol specific hydrogen-bond force. Organic bases lose their hydrogen-bond force but retain their nonspecific dipole-induced dipole force while 1-propanol loses its dipole-induced dipole force but retains its specific hydrogen-bond force after alkylating Wyodak coal. This interpretation of the data sugests that different modes exist on Wyodak coal for hydrogen bonding to 1-propanol than for hydrogen bonding to organic bases.

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Sequestration of Carbon Dioxide in Coal with Enhanced Coalbed Methane RecoveryA Review

et al. 2005

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This article reviews the storage of captured CO2 in coal seams. Other geologic formations, such as depleted petroleum reservoirs, deep saline aquifers and others have received considerable attention as sites for sequestering CO2. This review focuses on geologic sequestration of CO2 in unmineable coalbeds as the geologic host. Key issues for geologic sequestration include potential storage capacity, the storage integrity of the geologic host, and the chemical and physical processes initiated by the deep underground injection of CO2. The review topics include (i) the estimated CO2 storage capacity of coal, along with the estimated amount and composition of coalbed gas; (ii) an evaluation of the coal seam properties relevant to CO2 sequestration, such as density, surface area, porosity, diffusion, permeability, transport, rank, adsorption/desorption, shrinkage/swelling, and thermochemical reactions; and (iii) a treatment of how coalbed methane (CBM) recovery and CO2-enhanced coalbed methane (ECBM) recovery are performed (in addition, the use of adsorption/desorption isotherms, injection well characterization, and gas injection are described, as well as reservoir screening criteria and field tests operating in the United States and abroad); (iv) leak detection using direct measurements, chemical tracers, and seismic monitoring; (v) economic considerations using CO2 injection, flue gas injection, and predictive tools for CO2 capture/sequestration decisions; (vi) environmental safety and health (ES&H) aspects of CO2-enhanced coalbed methane/sequestration, hydrodynamic flow through the coal seam, accurate gas inventory, ES&H aspects of produced water and practices relative to ECBM recovery/sequestration; (vii) an initial set of working hypotheses concerning the chemical, physical, and thermodynamic events initiated when CO2 is injected into a coalbed; and (viii) a discussion of gaps in our knowledge base that will require further research and development. Further development is clearly required to improve the technology and economics while decreasing the risks and hazards of sequestration technology. These concerns include leakage to the surface, induced seismic activity, and long-term monitoring to verify the storage integrity. However, these concerns should not overshadow the major advances of an emerging greenhouse gas control technology that are reviewed in this paper.

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Surface Thermodynamics for Hydrocarbons on Wyodak Coals

Cited by 3 publications

References 41 publications

Flexible conformation in organic matter coatings: An hypothesis about soil water repellency

Flexible conformation in organic matter coatings: An hypothesis about soil water repellency

Surface Thermodynamics for Polar Adsorbates on Wyodak Coals

Sequestration of Carbon Dioxide in Coal with Enhanced Coalbed Methane RecoveryA Review

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