Importance of the accuracy of experimental data in the nonlinear chromatographic determination of adsorption energy distributions
- Univ. of Tennessee, Knoxville, TN (United States) Oak Ridge National Lab., TN (United States)
Adsorption energy distributions (AEDs) are calculated from the classical, fundamental integral equation of adsorption using adsorption isotherms and the expectation-maximization method of parameter estimation. The adsorption isotherms are calculated from nonlinear elution profiles obtained from gas chromatographic data using the characteristic points method of finite concentration chromatography. Porous layer open tubular capillary columns are used to support the adsorbent. The performance of these columns is compared to that of packed columns in terms of their ability to supply accurate isotherm data and AEDs. The effect of the finite column efficiency and the limited loading factor on the accuracy of the estimated energy distributions is presented. This accuracy decreases with decreasing efficiency, and approximately 5000 theoretical plates are needed when the loading factor, L[sub f], equals 0.56 for sampling of a unimodal Gaussian distribution. Increasing L[sub f] further increases the contribution of finite efficiency to the AED and causes a divergence at the low-energy endpoint if too high. This occurs as the retention time approaches the holdup time. Data are presented for diethyl ether adsorption on porous silica and its C-18-bonded derivative. 36 refs., 8 figs., 2 tabs.
- DOE Contract Number:
- FG05-88ER13859
- OSTI ID:
- 7080606
- Journal Information:
- Langmuir; (United States), Vol. 10:11; ISSN 0743-7463
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
ETHYL ETHER
ADSORPTION
CALCULATION METHODS
CAPILLARIES
COMPILED DATA
ENERGY SPECTRA
GAS CHROMATOGRAPHY
ISOTHERMS
SILICA
BLOOD VESSELS
BODY
CARDIOVASCULAR SYSTEM
CHALCOGENIDES
CHROMATOGRAPHY
DATA
ETHERS
INFORMATION
MINERALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
SEPARATION PROCESSES
SILICON COMPOUNDS
SILICON OXIDES
SORPTION
SPECTRA
400105* - Separation Procedures
400201 - Chemical & Physicochemical Properties
990200 - Mathematics & Computers