scholarly journals Determination of Heats of Adsorption of Triphenylchloromethane from Its Hexane Solution onto Dehydrated Silica–Alumina Surface

1979 ◽  
Vol 52 (8) ◽  
pp. 2195-2198 ◽  
Author(s):  
Hitofumi Taniguchi ◽  
Tatsuo Masuda ◽  
Kazuo Tsutsumi ◽  
Hiroshi Takahashi
Keyword(s):  
Alumina Surface ◽  
Heats Of Adsorption ◽  
Silica Alumina ◽  
Hexane Solution

Improved Codistillation Method for Determination of Carbon Tetrachloride, Ethylene Dichloride, and Ethylene Dibromide in Grain and Grain-Based Products

1985 ◽  
Vol 68 (4) ◽  
pp. 759-762
Author(s):  
Jonathan W Devries ◽  
Paul A Larson ◽  
Raymond H Bowers ◽  
Joyce A Keating ◽  
James M Broge ◽  
...  
Keyword(s):  
Carbon Tetrachloride ◽  
Internal Standard ◽  
Ethylene Dichloride ◽  
Standard Mixture ◽  
Ethylene Dibromide ◽  
Acetone Water ◽  
Relative Standard ◽  
The Common ◽  
Hexane Solution

Abstract A method is described for the determination of the common fumigants carbon tetrachloride (CC14), ethylene dichloride (EDC), and ethylene dibromide (EDB) in grain and grain-based products. A properly prepared sample is mixed with water and hexane, an internal standard mixture of 1,2-dichloropropane (DCP) and 1,2-dibromopropane (DBP) is added, and the fumigants are codistilled with the hexane into an appropriate receiver. After the hexane solution is dried over sodium sulfate, the quantities of fumigants present are quantitated on a gas chromatograph (GC) equipped with an electron capture detector (ECD). For the matrices investigated, the relative standard deviation of the method was 6.0,9.7, and 23.1% for CC14, EDC, and EDB, respectively. Recoveries of added fumigants were 107, 95, and 101%, respectively. Comparison with an acetone-water soak extraction method gave a correlation of 0.967 between methods for EDB with odds of a difference between methods of 35%.

Heterogeneous Interactions of Methylamines on porous Adsorbents Part II. Interactions on Silica–Alumina and Silica Gel Surfaces of Di- and Tri-methylamine in the Region of their Boiling Points

1972 ◽  
Vol 50 (15) ◽  
pp. 2451-2456 ◽  
Author(s):  
W. G. Cook ◽  
R. A. Ross
Keyword(s):  
Silica Gel ◽  
Surface Coverage ◽  
Adsorbed Layer ◽  
Silica Gels ◽  
Heats Of Adsorption ◽  
Boiling Points ◽  
Silica Alumina ◽  
Desorption Isotherms ◽  
Adsorption Desorption ◽  
Heterogeneous Interactions

The adsorption of di- and tri-methylamine has been studied at 280 and 276°K, respectively, on a range of silica gels and on silica–alumina. Adsorption–desorption isotherms and isothermal calorimetric heats of adsorption were measured. Heats of adsorption for di-methylamine on silica gel varied from 29.0 kcal/mol at θ = 0.05 to 12.0 kcal/mol at monolayer completion, while for silica–alumina the heats fell from 31.4 to 9.0 kcal/mol between these same values of surface coverage. For tri-methylamine on silica gel, heats fell from 21.0, θ = 0.05, to 10.3 kcal/mol, θ = 1.00, while heats of 21.4 and 9.9 kcal/mol, respectively, were found at these same surface coverages on silica–alumina. The values of the heats of adsorption are discussed in terms of interactions in the adsorbed layer which are believed to be influenced by the pore sizes in the adsorbent and by the basicity of the amine molecules.

Determination of the Orientation of Adsorbed Pyridine and γ-MPS on Alumina Surface by Photoacoustic FT-IR Spectroscopy

1986 ◽  
Vol 40 (6) ◽  
pp. 851-856 ◽  
Author(s):  
Marek W. Urban ◽  
Jack L. Koenig
Keyword(s):  
Surface Coverage ◽  
Hydroxyl Groups ◽  
Alumina Surface ◽  
Surface Hydroxyl ◽  
Adsorbed Pyridine ◽  
Ft Ir ◽  
Infrared Photoacoustic Spectroscopy ◽  
Pyridinium Ion ◽  
Ft Ir Spectroscopy

Fourier transform infrared photoacoustic spectroscopy has been applied to determine the structure and orientation of pyridine and γ-Metacryl-oxypropyltriethoxysilane (γ-MPS) on γ-Al2O3 surface. Adsorption of pyridine on activated γ-Al2O3 leads to formation of a pyridinium ion (pyN+-H) and pyridine N-oxide. The orientation of pyridinium ion on the alumina surface is random, whereas the pyridine N-oxide is parallel with respect to the surface. The adsorption of oligomers of γ-MPS gives parallel layers on the alumina surface. At low γ-MPS surface coverage, the carbonyl groups interact with the surface hydroxyl groups. Increasing surface coverage leads to an excess of the free C=O species.

The calorimetric determination of the heats of adsorption of oxygen on evaporated metal films

1960 ◽  
Vol 256 (1284) ◽  
pp. 81-105 ◽  
Keyword(s):  
Empirical Relation ◽  
Adsorbed Layer ◽  
Oxygen Adsorption ◽  
Heat Of Adsorption ◽  
Oxide Formation ◽  
Heats Of Adsorption ◽  
Surface Areas ◽  
Before And After ◽  
Surface Metal

A Beeck-type calorimeter has been used to measure the integral heat of adsorption of oxygen on evaporated films of titanium, chromium, manganese, iron, cobalt, nickel, niobium, molybdenum, rhodium, palladium, tantalum, tungsten, platinum and aluminium. The variation of the heat with the extent of the adsorption has also been determined, except with palladium, platinum and aluminium, for which the amounts of oxygen adsorption were too small to allow this to be done. The heats of adsorption reported are based on a careful determination of the heat capacity of the calorimeter and the overall error is not more than ± 5 kcal/mole. Some investigations of calorimetric behaviour have been made. The surface areas of the films have been measured before and after an adsorption by the B.E.T. method; krypton isotherms at — 196 °C were used for this purpose. From these data, it has been possible to estimate the number of atoms of oxygen adsorbed per surface metal atom. In most cases, this quantity, together with the heat of adsorption, can be related to the oxygen/metal ratios and the heats of formation of certain oxides; this observation is remarkable in view of the limited extent of the adsorption. In the cases of rhodium, palladium and platinum the adsorption stops short of a monolayer and is probably true chemisorption rather than oxide formation. For those metals on which oxide formation occurs, the decrease in heat of adsorption with increasing coverage has been interpreted, in general, in terms of an increase in the oxidation number of surface metal ions by electron transfer within the adsorbed layer. Some theoretical correlations between the heat of adsorption and the atomic and the bulk properties of the species concerned have been examined and found of little value; an empirical relation with the metallic radius is given.

Sign in / Sign up

Export Citation Format

Share Document