Abstract
The ability of a clay mineral surface to function as an acid is not represented by bulk pH measurements. A method using u.v. analysis and organic indicators has been developed to monitor surface acidity. The u.v. organic indicator method enables sensitive in situ quantification of surface-induced protonation in wet or dry clay systems. The clay preparation procedure used yields reproducible acidic behavior.
Résumé
L’aptitude de la surface d’une argile à fonctionner comme un acide n’est pas représentée par des mesures de pH effectuées sur la masse du produit. Une méthode utilisant l’analyse u.v. et des indicateurs organiques a été développée pour évaluer l’acidité de surface. La méthode u.v.-indicateur organique permet une quantification sensible in situ de la protonation induite par la surface dans les systèmes argile humide ou sèche. Le procédé utilisé pour la préparation de l’argile permet d’obtenir un comportement acide reproductible.
Kurzreferat
Die Fähigkeit einer Tonmineraloberfläche als Säure zu wirken, wird durch eine pH-Messung an der Gesamtprobe nicht widergegeben. Es wurde eine Methode entwickelt, um unter Verwendung der u.v.-Analyse und organischer Indikatoren die Oberflächenacidität zu bestimmen. Die u.v.-Indikator- methode ermöglicht empfindliche in situ Bestimmung oberflächeninduzierter Protonierung in nassen oder trockenen Tonsystemen. Das zur Präparafion der Tone benutzte Verfahren liefert reproduzierbare Aciditätseigenschaften.
Резюме
Способность поверхности глинистого минерала функционировать в качестве кислоты не выражается измерением рН в общей массе. Для проверки кислотности поверхности разработали метод анализа ультрафиолетовым спектром и органическими индикаторами. Метод ультрафиолетового органического индикатора дает возможность квантифицировать на месте протонацию, вызванную на поверхности влажной или сухой глины. Процедура приготовления глины дала возможность воспроизведения кислотного поведения поверхности.
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Bailey, G.W., Karickhoff, S.W. An Ultraviolet Spectroscopic Method for Monitoring Surface Acidity of Clay Minerals under Varying Water Content. Clays Clay Miner. 21, 471–477 (1973). https://doi.org/10.1346/CCMN.1973.0210607
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DOI: https://doi.org/10.1346/CCMN.1973.0210607