Macromolecular structure of coals. IV. Equilibrium swelling studies of coal networks subjected to various treatments

Lucht, Lucy M.; Peppas, Nicholas A.

doi:10.1002/app.1987.070330812

Cited by 10 publications

(5 citation statements)

References 1 publication

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“…Now it is widely accepted that coal consists of two major structural elements, aromatic clusters (mono-or fused aromatic rings with peripheral groups) (molecular state) and intercluster bridges (cross-link of alkyl and ethers groups with aromatic clusters) (macromolecular state). The molecular/ macromolecular model of coal was used to explain the dynamic of oxidation, swelling of coal in pyridine, molecular mobility, and extraction (Lucht et al, 1987;Lucht & Peppas, 2003;Takanohashi & Lino, 1994).…”

Section: Coal Structurementioning

confidence: 99%

Understanding the Chemical Properties of Macerals and Minerals in Coal and its Potential Application for Occupational Lung Disease Prevention

Huang

Finkelman

2008

Journal of Toxicology and Environmental Health, Part B

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Recent increases in oil price further strengthen the argument that coal and coal products will play an increasingly important role in fulfilling the energy needs of our society. Coal is an aggregate of heterogeneous substances composed of organic (macerals) and inorganic (minerals) materials. The objective of this review was to assess whether some chemical parameters in coal play a role in producing environmental health problems. Basic properties of coal--such as chemical forms of the organic materials, structure, compositions of minerals--vary from one coal mine region to another as well as from coals of different ranks. Most importantly, changes in chemical properties of coals due to exposure to air and humidity after mining--a dynamic process--significantly affect toxicity attributed to coal and environmental fate. Although coal is an extremely complex and heterogeneous material, the fundamental properties of coal responsible for environmental and adverse health problems are probably related to the same inducing components of coal. For instance, oxidation of pyrite (FeS2) in the coal forms iron sulfate and sulfuric acid, which produces occupational lung diseases (e.g., pneumoconiosis) and other environmental problems (e.g., acid mine drainage and acid rain). Calcite (CaCO3) contained in certain coals alters the end products of pyrite oxidation, which may make these coals less toxic to human inhalation and less hazardous to environmental pollution. Finally, knowledge gained on understanding of the chemical properties of coals is illustrated to apply for prediction of toxicity due to coal possibly before large-scale mining and prevention of occupational lung disease during mining.

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Section: Coal Structurementioning

confidence: 99%

Understanding the Chemical Properties of Macerals and Minerals in Coal and its Potential Application for Occupational Lung Disease Prevention

Huang

Finkelman

2008

Journal of Toxicology and Environmental Health, Part B

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“…These are covalent bonds, ionic linkages, hydrogen bonds, van der Waals forces, and π−π interactions. Of the five associative interactions hydrogen bonds, one of noncovalent associative interactions, are believed to play a key role to keep the macromolecular structure of low rank coals, − and hence utilization of the low rank coals is significantly affected by the hydrogen bonding. Since a large amount of water is retained in the lower rank coal due to the hydrogen bonds, drying is one of drawbacks for the utilization of the coal.…”

Section: Introductionmentioning

confidence: 99%

Estimation of Hydrogen Bond Distribution in Coal through the Analysis of OH Stretching Bands in Diffuse Reflectance Infrared Spectrum Measured by in-Situ Technique

et al. 2001

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A new method was presented to estimate the strength distribution of hydrogen bonds in coal. The hydrogen bonds include the coal intramolecule hydrogen bonds and coal-water hydrogen bonds formed by hydroxyls in coal. The method analyzes the FTIR spectrum ranging from 2400 to 3700 cm -1 obtained using the in-situ diffuse reflectance IR Fourier transform (DRIFT) technique with neat, undiluted, coal samples. The FTIR spectra during the heat-up of eight coals (seven Argonne premium coals and an Australian brown coal), an ion-exchange resin, and a lignin were measured every 20 °C from room temperature to 300 °C. Each spectrum was divided into six hydrogen-bonded absorption bands by a curve-resolving method, then the amount of hydroxyls contributing to each hydrogen bond was estimated by Beer's law by using different absorptivity for each band. The strength of each hydrogen bond was estimated using a relation presented by Drago et al. that is known as one of the "linear enthalpy-spectroscopic shift relations". Using this analysis method, changes in hydrogen bond distributions (HBD) with increasing temperature were successfully estimated for all the samples examined. By utilizing the HBD the changes in enthalpies associated with the desorption of adsorbed water, the glass transition, and the decomposition of COOH groups were well estimated. Only FTIR spectra measurements were found to be enough to obtain such enthalpies. This greatly simplified the calculation procedure and increased the accuracy of the enthalpies. The validity of the proposed in situ FTIR measurement method and the analysis method for obtaining HBD was well clarified.

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“…By contrast, humic substances (fulvic acid, humic acid, and humin, often bound to remnant biomolecules) (27,28), unstructured kerogens (29,30), and low rank coals (29,31,32) are macromolecular solids with flexible pores. Their macromolecules contain highly functionalized aliphatic, alicyclic, aromatic, and heteroaromatic backbones crosslinked by metal ions or covalent bonds.…”

Section: Introductionmentioning

confidence: 99%

“…While coals are highly cross-linked, NMR studies show they contain an abundance of mobile nuclei (33). Natural macromolecular solids are capable of absorbing small molecules into their matrix and swelling as a result (31,32,34,35).…”

Section: Introductionmentioning

confidence: 99%

Detailed Sorption Isotherms of Polar and Apolar Compounds in a High-Organic Soil

Xia

Pignatello

2000

Environ. Sci. Technol.

168

130

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Sorption isotherms of 13 apolar liquids and solids and polar solids-six in unprecedented detail-are used to evaluate a polymer-based model for natural organic matter. While all isotherms are nonlinear, the "running" Freundlich exponent n varies markedly with concentration. The isotherms show linear-scale inflection consistent with the presence of flexible (deformable) porosity as predicted by the glassy polymer-based Extended Dual-Mode Model (EDMM). The EDMM assumes dissolution and hole-filling domains in the organic solid, with provision for sorbate-caused plasticization of the solid and "melting" of the holes. Features of the EDMM are illustrated for chlorinated benzenes in poly(vinyl chloride). The solutes fall into categories of "hard" (aliphatics and 2,4-dichlorophenol) and "soft" (chlorinated benzenes, 2-chloronitrobenzene) according to their ability to plasticize organic matter. Comparison of domain coefficients at infinite dilution reveals that organic solutes have a modestly greater affinity for holes than dissolution sites (by 0.1-0.6 log unit), as expected by the polymer model. Sorption of CHCl3 shows time-dependent hysteresis diminished at high concentrations by the plasticizing effect. Sorption of CHCl3 also shows a type of hysteresis for glassy solids known as the "conditioning effect" in which high loading of sorbate increases hole population upon its removal and thus leads to enhanced uptake and nonlinearity when a second sorption is performed. A Polanyi-based, fixed-pore filling model applied to the adsorption component of the isotherms gave widely variant volumetric pore capacity, contrary to its own stipulations, and could not explain the hysteresis.

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Macromolecular structure of coals. IV. Equilibrium swelling studies of coal networks subjected to various treatments

Cited by 10 publications

References 1 publication

Understanding the Chemical Properties of Macerals and Minerals in Coal and its Potential Application for Occupational Lung Disease Prevention

Understanding the Chemical Properties of Macerals and Minerals in Coal and its Potential Application for Occupational Lung Disease Prevention

Estimation of Hydrogen Bond Distribution in Coal through the Analysis of OH Stretching Bands in Diffuse Reflectance Infrared Spectrum Measured by in-Situ Technique

Detailed Sorption Isotherms of Polar and Apolar Compounds in a High-Organic Soil

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