Analysis of the surface heterogeneity of unmodified and modified silica by capillary inverse gas-solid chromatography at finite dilution
- Univ. of Tennessee, Knoxville, TN (United States) Oak Ridge National Lab., TN (United States)
The adsorption energy distributions (AEDs) of several molecular probes on two silica samples were determined from their chromatographic retention data. Adsorption data were obtained using the elution-by-characteristic points (ECP) method of capillary inverse gas chromatography at finite dilution. The diffuse rear profiles of the bands obtained with samples of different sizes overlay consistently. The numerical expectation-maximization (EM) method has been applied to the calculation of the AEDs from the unfitted experimental adsorption isotherms, using the Langmuir model for the local adsorption isotherm. Two silica samples, both unmodified and reacted with trimethylchlorosilane, were used. Results were obtained with methanol, diethyl ether, 1-chlorobutane, dichloromethane, and toluene. Their AEDs exhibit two high-energy peaks, around 45-60 and 50-70 kJ/mol, respectively. The differences observed for the specific capacities of adsorption and for the energy distributions of the unmodified and modified silicas are correlated with the chemical structure of the probe and the adsorbent surface. 17 refs., 10 figs., 4 tabs.
- DOE Contract Number:
- FG05-88ER13859
- OSTI ID:
- 7020123
- Journal Information:
- Langmuir; (United States), Vol. 10:5; ISSN 0743-7463
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
SILICA
SURFACE PROPERTIES
ADSORPTION
CHROMATOGRAPHY
COMPILED DATA
DILUTION
ETHYL ETHER
MATHEMATICAL MODELS
METHANOL
METHYLENE CHLORIDE
ORGANIC CHLORINE COMPOUNDS
SILANES
TOLUENE
ALCOHOLS
ALKYLATED AROMATICS
AROMATICS
CHALCOGENIDES
DATA
ETHERS
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
MINERALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANIC SILICON COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
SEPARATION PROCESSES
SILICON COMPOUNDS
SILICON OXIDES
SORPTION
360606* - Other Materials- Physical Properties- (1992-)
400105 - Separation Procedures
400201 - Chemical & Physicochemical Properties
990200 - Mathematics & Computers