Gas-solid chromatographic properties of alkali-metal modified silica

Kopečni, M. M.; Miljonic, S. K.; Laub, R. J.

doi:10.1021/ac50057a009

Cited by 28 publications

(5 citation statements)

References 16 publications

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“…In literature there are similar results for silica (6), for microporous carbon (30), carbon fibers (4), graphitized carbon black, macroporous silicagel (9), zeolites (9,31), and Pt/Al 2 O 3 catalyst (32,33). …”

Section: Aşki̇n and İnelsupporting

confidence: 68%

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EVALUATION OF THE HEAT OF ADSORPTION OF SOME n-ALKANES ON ALUMINA AND ZEOLITE BY INVERSE GAS CHROMATOGRAPHY

Aşkın

Inel

2001

Separation Science and Technology

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The isosteric heat of adsorption of some n-alkanes (n-C 5 to n-C 8 ) on some adsorbents(activated alumina, natural zeolite(clinoptilolite) and 13X molecular sieve) were evaluated by inverse gas chromatography using the temperature dependence of adsorption.The isosteric heat of adsorption of the probes on alumina and clinoptilolite were determined in the finite concentration region, and those on 13X were determined in the infinite dilution region.It was found that the adsorption isotherms for alumina and clinoptilolite conform with the Langmuir equation, and the isosteric heats of adsorption increase linearly with increasing carbon number of the probes for alumina and 13X.

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Section: Aşki̇n and İnelsupporting

confidence: 68%

“…Many physicochemical properties such as activity coefficient (1), diffusion coefficient (2), Henry's constants (3), surface acidity (4), surface area (5), and adsorption enthalpy, entropy, and free energy (6,7) can be measured by GC.…”

Section: Introductionmentioning

confidence: 99%

EVALUATION OF THE HEAT OF ADSORPTION OF SOME n-ALKANES ON ALUMINA AND ZEOLITE BY INVERSE GAS CHROMATOGRAPHY

Aşkın

Inel

2001

Separation Science and Technology

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“…The method used for preparing the silylating samples was the same as that described earlier; the sample was refluxed in a Soxhlet by 30 vol% of dimethyldichlorosilane in toluene for 6 h. Then, the sample was removed from the Soxhlet, washed by deionized water, and dried at 120 ∘ C overnight. [12,13]. The modification of the surface properties of alumina with alkali metal chloride (NaCl) is described for parent and calcined samples dependent on a 10% salt loading.…”

Section: Preparation Of Aluminamentioning

confidence: 99%

Characterization of Modified and Polymer Coated Alumina Surfaces by Infrared Spectroscopy

Elnaggar¹

2013

Journal of Spectroscopy

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The prepared, modified, and coated alumina surfaces were characterized by infrared spectroscopy (FTIR) to investigate the surface properties of the individual and double modified samples. FTIR helps in reporting the changes occurred in hydroxyl groups as well as the structure changes as a result of thermal treating, hydrothermal treating, silylation treating, alkali metal treating, coating, and bonding with polymer. FTIR spectroscopy represents the strength and abundance of surface acidic OH which determine the adsorption properties of polar and nonpolar sorbents. Generally, all treated samples exhibit decrease of OH groups compared with those of parent ones producing alumina surfaces of different adsorptive powers.

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“…In this case, VNR can be written as a linear combination of the concurrent contributions of the adsorption equilibria on the bare surface of an Na2HPO4 monolayer and the thin crystalline layer of Na2HPO4 to solute retention, VNR KASMT (/f'Kc a'KA)XCO + (/3'Kc -a'KA)XC (4) where Kc is a distribution constant for the adsorption equilibrium of a solute on the surface of the thin crystalline layer of Na2HP04.…”

Section: Methodsmentioning

confidence: 99%

Characterization of Salt-Modified Silica Gel Coated with Disodium Hydrogenphosphate as an Adsorbent for Gas-Solid Chromatography

et al. 1995

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A simple, effective modification of the surface properties of an adsorbent for gas-solid chromatography (GSC) has been studied by coating the adsorbent surface with various inorganic salts.1-13 Although most authors have focused their interest on effect of the nature of the salt used as a modifier on the retention volume, they have rarely done so concerning influence of the amount of salt coated. In previous studies14,15 we elucidated dependence of the retention volume of a given solute on the amount of loaded salt (the salt-loading) on the basis of a mixed retention mechanism. Reasonable values could be calculated regarding the distribution constants of the adsorption equilibria on the subsurfaces formed on the surface of a salt-modified adsorbent. In the present study we examined the same approach as that used for characterization of a salt-modified silica-gel adsorbent coated with disodium hydrogen phosphate as a less reactive salt than the previously used potassium fluoride. ExperimentalSilica gel (Fujigel KC 5) was dried at 120° C for 15 h after sizing into a 60 -80 mesh fraction. Crystalline disodium hydrogenphosphate (Na2HPO4 12H20) was heated at 120° C for 5 h to be converted to an anhydrous salt prior to weighing. Na2HP04-coated silica-gel beads were prepared by depositing salt on silica gel by evaporating water, and packed into a stainless-steel column (100X0.3 cm i.d.) by tapping. The packed column was conditioned at 150°C for 15 h in a nitrogengas stream at a flow rate of 40 cm3 min' and at 120° C for 3 h in a helium-gas stream at the same flow rate as that before use. A Hitachi Model 263-30 gas chromatograph, equipped with a thermal-conductivity detector, was used along with a Hitachi Model D-2500 Chromatointegrator.Chromatographic measurements were made at 60 and 120° C using helium as the carrier gas at a flow rate of 40 cm3 mine. The reduced retention volume (VNR) and salt-loading (XC) were calculated by dividing the net retention volume of each solute by the weight of the salt-free silica gel packed into the column, and as a weight ratio (the anhydrous salt loaded/the saltfree silica gel), respectively. The specific surface area of salt-coated silica-gel beads (As; on the basis of unit weight of the salt-free silica gel) was measured by a BET method of nitrogen adsorption. Resultsand Discussion

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Gas-solid chromatographic properties of alkali-metal modified silica

Cited by 28 publications

References 16 publications

EVALUATION OF THE HEAT OF ADSORPTION OF SOME n-ALKANES ON ALUMINA AND ZEOLITE BY INVERSE GAS CHROMATOGRAPHY

EVALUATION OF THE HEAT OF ADSORPTION OF SOME n-ALKANES ON ALUMINA AND ZEOLITE BY INVERSE GAS CHROMATOGRAPHY

Characterization of Modified and Polymer Coated Alumina Surfaces by Infrared Spectroscopy

Characterization of Salt-Modified Silica Gel Coated with Disodium Hydrogenphosphate as an Adsorbent for Gas-Solid Chromatography

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