scholarly journals Non-Linear Enthalpy-Entropy Correlation for Nitrogen Adsorption in Zeolites

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 2978 ◽  
Author(s):  
Montserrat Delgado ◽  
Carlos Arean
Keyword(s):  
Infrared Spectroscopy ◽  
Linear Correlation ◽  
Variable Temperature ◽  
Nitrogen Adsorption ◽  
Porous Solids ◽  
Separation And Purification ◽  
N2 Adsorption ◽  
Adsorption Enthalpy ◽  
Non Linear

The thermodynamics of dinitrogen adsorption in faujasite-type zeolites, Na-Y, Ca-Y and Sr-Y, were investigated by means of variable-temperature infrared spectroscopy, a technique that affords determination of the standard adsorption enthalpy (ΔH0) and entropy (ΔS0) from an analysis of the IR spectra recorded over a range of temperatures. The results obtained, taken together with previously reported values for N2 adsorption on protonic zeolites, revealed a non-linear correlation between ΔH0 and ΔS0. Implications of such a correlation for gas separation and purification by adsorption in porous solids are highlighted.

scholarly journals Structure and Stability of Gas Adsorption Complexes in Periodic Porous Solids as Studied by VTIR Spectroscopy: An Overview

2020 ◽  
Vol 10 (23) ◽  
pp. 8589
Author(s):  
Montserrat R. Delgado
Keyword(s):  
Gas Adsorption ◽  
Variable Temperature ◽  
Spectroscopic Technique ◽  
Porous Solids ◽  
Large Temperature ◽  
Adsorption Complexes ◽  
The Stability ◽  
Standard Enthalpy Change

Variable-temperature infrared (VTIR) spectroscopy is an instrumental technique that enables structural characterization of gas-solid adsorption complexes by analysis of meaningful vibrational modes, and simultaneous determination of the standard enthalpy change (ΔH0) involved in the gas adsorption process, which allows one to quantify the stability of the corresponding complex. This is achieved by a van’t Hoff analysis of a set of IR spectra recorded over a sufficiently large temperature range. Herein, the use of this versatile spectroscopic technique is demonstrated by reviewing its application to the study of carbon monoxide, carbon dioxide and dinitrogen adsorption on several (alkaline) zeolites, which can be regarded as the archetype of periodic porous solids.

Quantitative determination of polymer and mineral content in paper coatings by infrared spectroscopy. Improvements by non-linear treatments

1996 ◽  
Vol 335 (1-2) ◽  
pp. 79-85 ◽  
Author(s):  
N. Dupuy ◽  
C. Ruckebusch ◽  
L. Duponchel ◽  
P. Beurdeley-Saudou ◽  
B. Amram ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Quantitative Determination ◽  
Mineral Content ◽  
Paper Coatings ◽  
Non Linear

scholarly journals Effect of sample dilution on estimated values of antioxidant capacity by photochemiluminiscence method

2012 ◽  
Vol 60 (8) ◽  
pp. 67-72 ◽  
Author(s):  
Pavel Híc ◽  
Josef Balík
Keyword(s):  
Antioxidant Capacity ◽  
Linear Correlation ◽  
Amount Of Substance ◽  
Dependent Change ◽  
Molar Amount ◽  
Non Linear ◽  
Sample Dilution ◽  
Lipid Soluble Antioxidant

This paper describes principles of a proper dilution of samples used for the determination of antioxidant capacity by means of a photochemiluminiscence method using the instrument Photochem (Analytik Jena AG). The authors used the method ACL (Lipid-soluble Antioxidant Capacity), which is one of two methods enabling to measure in this instrument. It was demonstrated that values measured by the photochemiluminiscence method ACL were influenced by the degree of sample dilution. When studying effects of dilution of samples of wine and rutin, it was demonstrated that there is a non-linear correlation between the degree of dilution and measured values of antioxidant capacity. At low molar amount of substance (i.e. at 0.5 and 1.0 nmol), the measured value of rutin inhibition was higher than the same that molar amount of trolox. At higher molar amounts (i.e. 3; 4 and 5 nmol), the inhibition value of trolox was higher. This dependent change can be explained by means of a different effectiveness of antioxidants and a different stability of their products with radicals.

Determination of Concrete Cube Strength from Used Samples / Určení Krychelné Pevnosti Betonu U Použitých Zkušebních Trámců

2012 ◽  
Vol 12 (2) ◽  
pp. 186-194 ◽  
Author(s):  
Oldřich Sucharda ◽  
David Mikolášek ◽  
Jiří Brožovský
Keyword(s):  
Compressive Strength ◽  
Concrete Beams ◽  
Linear Analysis ◽  
Bending Tests ◽  
Cube Strength ◽  
Non Linear ◽  
Compressive Strength Of Concrete ◽  
Concrete Cube

Abstract This paper deals with the determination of compressive strength of concrete. Cubes, cylinders and re-used test beams were tested. The concrete beams were first subjected to three-point or fourpoint bending tests and then used for determination of the compressive strength of concrete. Some concrete beams were reinforced, while others had no reinforcement. Accuracy of the experiments and calculations was verified in a non-linear analysis.

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