Determination of acidic functional groups in low-rank coals: comparison of ion-exchange and non-aqueous titration methods

Maher, Thomas P.; Schäfer, H.

doi:10.1016/0016-2361(76)90010-7

Cited by 29 publications

(3 citation statements)

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“…Maher and Schafer (35) found that the carboxyl contents determined with non-aqueous titration were always higher than those found by exchange with barium acetate. They infer from these results that some of the phenols may be titrating with the carboxyl groups due to the effect of the basic solvent ethylenediamine.…”

Section: Non-aqueous Titration Techniquesmentioning

confidence: 90%

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Inorganic constituents in American lignites

Morgan

Jenkins

Walker

1981

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Both the discrete mineral phases and the ion-exchangeable inorganic components of lignites from Texas, North Dakota and Montana have been studied. The ion-exchangeable cations and the carboxyl groups with which they are associated were characterized by ion exchange methods utilizing ammonium acetate and barium acetate, respectively. Na, K, Mg, Ca, Sr, ahd Ba were found to be present in all three coals. It was found that Ca and Mg were the most abundant cations and that 40-60% of the carboxyl groups in the raw coals were exchanged with cations. Also, significant variations in the relative and absolute concentrations of all the cations were observed. The discrete mineral phases in these lignites were studied by semiquantitative x-ray diffraction and infrared spectroscopy. The importance of the cations in •this analysis was shown when the mineralogical analyses of the low temperature ~sh of the coals with the cations removed and the raw coals were compared. Results show that up to 50% of the low temperature ash of these raw coals can be attributed to the existence of metal cations and that fixation of sulfur, carbon, and oxygen to form sulfates and carbonates is the major reason for this contribution.

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Section: Non-aqueous Titration Techniquesmentioning

confidence: 90%

“…al. (8,34,35) investigated the use of this m&thod in the determination of 'arboxyl groups in coal. One of the principle advantages for its use on coal is that ethylenediamine causes swelling.…”

Section: Non-aqueous Titration Techniquesmentioning

confidence: 99%

Inorganic constituents in American lignites

Morgan

Jenkins

Walker

1981

Fuel

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“…As evidenced by both quantum chemical calculations and a variety of characterization means, this adsorption-enhancing effect is attributed to the hydrogen bond interactions between hydrogen atoms on the carbon surface and CO 2 molecules, which is greatly enhanced by the presence of O atoms on the carbon surface. As we know, most oxygen-containing functional groups such as phenolic hydroxyl groups, carboxyl groups, lactone groups, and aldehyde groups show acid tendency [ 29 ]. According to the acid-base interacting mechanism currently accepted in this field, the presence of such acidic groups would show a negative effect on CO 2 adsorption.…”

Section: Introductionmentioning

confidence: 99%

Oxygen-containing functional group-facilitated CO2 capture by carbide-derived carbons

et al. 2014

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A series of carbide-derived carbons (CDCs) with different surface oxygen contents were prepared from TiC powder by chlorination and followed by HNO3 oxidation. The CDCs were characterized systematically by a variety of means such as Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ultimate analysis, energy dispersive spectroscopy, N2 adsorption, and transmission electron microscopy. CO2 adsorption measurements showed that the oxidation process led to an increase in CO2 adsorption capacity of the porous carbons. Structural characterizations indicated that the adsorbability of the CDCs is not directly associated with its microporosity and specific surface area. As evidenced by elemental analysis, X-ray photoelectron spectroscopy, and energy dispersive spectroscopy, the adsorbability of the CDCs has a linear correlation with their surface oxygen content. The adsorption mechanism was studied using quantum chemical calculation. It is found that the introduction of O atoms into the carbon surface facilitates the hydrogen bonding interactions between the carbon surface and CO2 molecules. This new finding demonstrated that not only the basic N-containing groups but also the acidic O-containing groups can enhance the CO2 adsorbability of porous carbon, thus providing a new approach to design porous materials with superior CO2 adsorption capacity.

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