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5. Obtaining adsorption-desorption isotherms
5.1 Sample preparation
Prior to any adsorption, the surface of the samples studied must be cleaned of any species retained by physical adsorption.
This degassing operation must be carried out very carefully if reproducible results are to be obtained.
In theory, it would be sufficient to create a high vacuum above the sample; in practice, heating the sample is required to accelerate desorption. However, it is important to choose a temperature that will not degrade the sample (as in the case of organic solids) or alter its surface properties.
Sample processing conditions can be optimized by prior thermal analysis, in particular by thermogravimetry
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Obtaining adsorption-desorption isotherms
Assessment of specific areas
Bibliography
- (1) - THOMMES (M.), KANEKO (K.), NEIMARK (A.V.), OLIVIER (J.P.), RODRIGUEZ-REINOSO (F.), ROUQUEROL (J.S.W.), SING (K.S.W.) - Physisorption of gases, with special reference to the evaluation of surface area and pore size distribution (IUPAC Technical Report) . - Pure and Appl. Chem., 87(9-10), p. 1051-1069...
Software tools
Excel sheet for BET and "t" calculations ("physi view calc") http://www.micromeritics.com/Library/Freeware-Software.aspx
Events
On a national scale: Annual days of the French Adsorption Association, usually in January-February. http://www.adsorption.fr/spip.php?rubrique1
On an international scale: Fundamentals of Adsorption (FOA), organized by the International Adsorption Society and rotating between Europe, America and Asia, every three years...
Standards and norms
- Détermination de l'aire massique (surface spécifique) des poudres par adsorption de gaz. Méthode BET : mesure volumétrique par adsorption d'azote à basse température, p. 175-186 - NF. X 11-621 - 11-75
- Determination of the specific surface area of solids by gas adsorption – BET method - ISO 9277 - 2010
- Standard test method for advanced ceramic specific surface area by physical adsorption - ASTM C1274-12...
Regulations, safety
Use of liquid nitrogen http://bip.cnrs-mrs.fr/acmo/node8.html
Handling nanomaterials and nanoparticles http://www.inrs.fr/risques/nanomateriaux/prevention-risques.html
Gas handling...
Equipment sold
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Choosing a device
A list of commercial adsorption manometers for use with nitrogen at its normal liquefaction temperature is given in the following tables. Some of these only give access to the specific surface area (tables 1 and
Associations (non-exhaustive list)
Association Française d'Adsorption (AFA) French-speaking association whose aim is to promote the advancement of experimental, numerical and theoretical methods in the fields of adsorption from liquid or gaseous phases, on solid surfaces or in porous materials, and which organizes annual conferences often accompanied by a "School" day.
Training courses and seminars (non-exhaustive list)
CNRS-Formation Entreprises, 2 ½-day course entitled "Gas adsorption and applications: materials characterization and gas separation or storage" organized at the MADIREL laboratory http://cnrsformation.cnrs.fr
Laboratories (non-exhaustive list)
MADIREL Laboratory, Aix-Marseille University, CNRS, UMR 7246, St Jérôme Campus
Laboratories affiliated to the Association Française d'Adsorption, a list of which, with a link to its own web page, can be found at http://www.adsorption.fr/spip.php?rubrique2
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