Effective surface areas of coals measured by dye adsorption
The primary interest has been to examine adsorption behavior especially at short contact times, ten minutes to an hour, to determine whether such measurements might give useful data on effective surface areas - i.e., the surface that would be accessible to reagents within times comparable to those typical of most coal processing. Accordingly, most of the emphasis is on the effect of time on adsorption, rather than on traditional adsorption isotherms. Although most literature on cationic dye adsorption (mostly on carbons) uses methylene blue, it happened that the authors originally used safranin O instead because this dye was reported to be useful in distinguishing oxidized coals from fresh coals. Many of their experiments were repeated using methylene blue (in water), with very similar results. It was noted early that swelling of coals in water was common, especially for more oxidized or lower rank coals, and adsorption experiments were also done in another solvent, namely methanol. This produced quite striking differences for some coals. Coal surfaces that are readily accessible to adsorption by safranin are found to correlate well with N/sub 2/ surface areas, with adsorption of 1.0 mg safranin per gram of coal corresponding to essentially a surface area of 1.0 m/sup 2//g. Highly oxidized coals were found to swell considerably in water, with correspondingly increased adsorption. Areas of such coals can be estimated by adsorption of safranin from methanol solutions.
- Research Organization:
- American Cyanamid Co., Stamford, CT (USA)
- OSTI ID:
- 5933232
- Report Number(s):
- CONF-8809271-
- Journal Information:
- Prepr. Pap., Am. Chem. Soc., Div. Fuel Chem.; (United States), Vol. 33:4; Conference: Surface chemistry of coal, Los Angeles, CA, USA, 25-30 Sep 1988
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BITUMINOUS COAL
SURFACE AREA
ADSORPTION
ADSORPTION ISOTHERMS
ASH CONTENT
CHEMICAL PROPERTIES
DYES
MEASURING METHODS
METHANOL
NITROGEN
OXIDATION
SWELLING
WATER
ALCOHOLS
BLACK COAL
CARBONACEOUS MATERIALS
CHEMICAL REACTIONS
COAL
ELEMENTS
ENERGY SOURCES
FOSSIL FUELS
FUELS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
ISOTHERMS
MATERIALS
NONMETALS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
SORPTION
SURFACE PROPERTIES
010600* - Coal
Lignite
& Peat- Properties & Composition