scholarly journals Inverse gas chromatography of chromia. Part I. Zero surface coverage

2001 ◽  
Vol 66 (4) ◽  
pp. 259-271 ◽  
Author(s):  
A.E. Onjia ◽  
S.K. Milonjic ◽  
Lj.V. Rajakovic
Keyword(s):  
Gas Chromatography ◽  
Surface Energy ◽  
Inverse Gas Chromatography ◽  
Surface Coverage ◽  
Crystalline Form ◽  
Free Energies ◽  
Solid Samples ◽  
Acid Base ◽  
Basic Character ◽  
Vapour Mixture

The surface properties of the solid obtained from colloidal chromiawere investigated by inverse gas chromatography (IGC), at zero surface coverage conditions. The solid samples I dried at 423 K and II heated at 1073 K in the amorphous and crystalline form, respectively, were studied in the temperature range 383-423 K. The dispersive components of the surface free energies, enthalpies, entropies, and the acid/base constants for the solidswere calculated from the IGCmeasurements and compared with the data for a commercially available chromia (III). Significantly lower enthalpies and entropies were obtained for cyclohexane on solid II and chloroform, highly polar organic, on solid I. The dispersive contributions to the surface energy of solid II and III were similar, but much greater in the case of solid I. All the sorbents had a basic character, with the KD/KA ratio decreasing in the order I > II > III. The retention and resolution in the separation of a vapour mixture of C5-C8 n-alkanes on the three substrates were different.Arapid separationwas observed on solid II and an enhanced retention on solid I. Generally, the heated chromia (II) exhibited diminished adsorption capacity, and enhanced homogeneity of the surface.

scholarly journals Surface characterization of polymers by inverse gas chromatography

2007 ◽  
Vol 72 (4) ◽  
pp. 403-406 ◽  
Author(s):  
Aleksandra Nastasovic ◽  
Antonije Onjia
Keyword(s):  
Glycidyl Methacrylate ◽  
Surface Characterization ◽  
Infinite Dilution ◽  
Inverse Gas Chromatography ◽  
Surface Coverage ◽  
Isosteric Heat ◽  
Free Energies ◽  
Acid Base ◽  
Adsorption Energy Distribution

An inverse gas chromatographic (IGC) study of the sorption properties of macroporous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate), PGME, and PGME modified with ethylene diamine, PGME-en, was presented. At infinite dilution, the thermodynamic parameters of adsorption, the dispersive components of the surface free energies, the acid/base constants and the interaction parameters for the initial and modified copolymer samples were investigated. The adsorption isotherms determined by IGC under conditions of finite surface coverage were used to estimate the surface area, the isosteric heat of adsorption and the adsorption energy distribution on the surface of the initial and modified copolymer samples. .

scholarly journals Application of inverse gas chromatography for polymer characterization

2007 ◽  
Vol 61 (6) ◽  
pp. 342-349
Author(s):  
Aleksandra Nastasovic ◽  
Antonije Onjia ◽  
Slobodan Milonjic ◽  
Slobodan Jovanovic
Keyword(s):  
Gas Chromatography ◽  
Ethylene Glycol ◽  
Glycidyl Methacrylate ◽  
Infinite Dilution ◽  
Inverse Gas Chromatography ◽  
Glycol Dimethacrylate ◽  
Free Energies ◽  
Acid Base ◽  
Polymer Characterization ◽  
Suspension Copolymerization

The possibility of polymer characterization by inverse gas chromatography (IGC) was illustrated with the study of sorption properties of macroporous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate), PGME, synthesized by suspension copolymerization, and copolymer modified with ethylene diamine, PGME-en. The data collected from IGC experiments at infinite dilution are used for the calculation of the thermodynamic parameters of adsorption, dispersive components of the surface free energies, and the acid/base constants. .

Inverse gas chromatography for natural fibre characterisation: dispersive and acid-base distribution profiles of the surface energy

Cellulose ◽  
2017 ◽  
Vol 24 (11) ◽  
pp. 4691-4700 ◽  
Author(s):  
A. Legras ◽  
A. Kondor ◽  
M. Alcock ◽  
M. T. Heitzmann ◽  
R. W. Truss
Keyword(s):  
Gas Chromatography ◽  
Surface Energy ◽  
Inverse Gas Chromatography ◽  
Natural Fibre ◽  
Acid Base

Evaluation of the dispersive component of the surface energy of active carbons as determined by inverse gas chromatography at zero surface coverage

2008 ◽  
Vol 1214 (1-2) ◽  
pp. 121-127 ◽  
Author(s):  
M. Pérez-Mendoza ◽  
M.C. Almazán-Almazán ◽  
L. Méndez-Liñán ◽  
M. Domingo-García ◽  
F.J. López-Garzón
Keyword(s):  
Gas Chromatography ◽  
Surface Energy ◽  
Inverse Gas Chromatography ◽  
Surface Coverage ◽  
Active Carbons ◽  
Dispersive Component

scholarly journals New approach to determine the surface and interface thermodynamic properties of H-β-zeolite/rhodium catalysts by inverse gas chromatography at infinite dilution

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tayssir Hamieh ◽  
Ali Ali Ahmad ◽  
Thibault Roques-Carmes ◽  
Joumana Toufaily
Keyword(s):  
Gas Chromatography ◽  
Linear Regression ◽  
Surface Energy ◽  
Infinite Dilution ◽  
Inverse Gas Chromatography ◽  
Acid Base ◽  
Dispersive Component ◽  
Β Zeolite ◽  
Gamma S

AbstractThe thermodynamic surface properties and Lewis acid–base constants of H-β-zeolite supported rhodium catalysts were determined by using the inverse gas chromatography technique at infinite dilution. The effect of the temperature and the rhodium percentage supported by zeolite on the acid base properties in Lewis terms of the various catalysts were studied. The dispersive component of the surface energy of Rh/H-β-zeolite was calculated by using both the Dorris and Gray method and the straight-line method. We highlighted the role of the surface areas of n-alkanes on the determination of the surface energy of catalysts. To this aim various molecular models of n-alkanes were tested, namely Kiselev, cylindrical, Van der Waals, Redlich–Kwong, geometric and spherical models. An important deviation in the values of the dispersive component of the surface energy $${\gamma }_{s}^{d}$$ γ s d determined by the classical and new methods was emphasized. A non-linear dependency of $${\gamma }_{s}^{d}$$ γ s d with the specific surface area of catalysts was highlighted showing a local maximum at 1%Rh. The study of RTlnVn and the specific free energy ∆Gsp(T) of n-alkanes and polar solvents adsorbed on the various catalysts revealed the important change in the acid properties of catalysts with both the temperature and the rhodium percentage. The results proved strong amphoteric behavior of all catalysts of the rhodium supported by H-β-zeolite that actively react with the amphoteric solvents (methanol, acetone, tri-CE and tetra-CE), acid (chloroform) and base (ether) molecules. It was shown that the Guttmann method generally used to determine the acid base constants KA and KD revealed some irregularities with a linear regression coefficient not very satisfactory. The accurate determination of the acid–base constants KA, KD and K of the various catalysts was obtained by applying Hamieh’s model (linear regression coefficients approaching r2 ≈ 1.000). It was proved that all acid base constants determined by this model strongly depends on the rhodium percentage and the specific surface area of the catalysts.

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