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A Direct Procedure for Determining the number of Plates in Tactoids of Smectites: The Na/Ca-Montmorillonite Case

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Clays and Clay Minerals

Abstract

The dispersion of clays is of great importance in determining various soil properties such as hydraulic conductivity. A procedure which involves fixing followed by embedding of clay particles in an epoxy resin is described. This procedure enables the observation of cross sections of clay tactoids under a transmittance electron microscope, and the determination of the number of plates per tactoid. The use of the procedure for the determination of the relation between the exchangeable sodium percentage (ESP) and tactoid size in suspensions of a Na/Ca bentonite system is presented. It was demonstrated that even at ESP 5 significant dispersion already occurs, the average number of plates per tactoid being 6.6 as compared to 16.1 at ESP 0.

Резюме

Дисперсия глин имеет огромное значение при определении различных свойств почвы, таких как гидравлическая проводимость. Описывается процедура, которая включает фиксирование и внесение глинистых частиц в эпоксидную смолу. Эта процедура позволяет наблюдать профиль глинистых тактоидов под просвечивающим электронным микроскопом и определять число пластин на тектоид. Описывается испльзование процедуры для определения отношения между обменным количеством натрия /ОКН/ и размером тектоида в суспензиях бентонитовой системы Na/Ca. Было показано, что даже при OКН=5 уже наблюдается значительная дисперсия, среднее число пластин на тактоид достигает 6,6 по сравнению с 16,1 при ОКН=0.

Kurzreferat

Die Dispersion von Tonerden ist von großer Wichtigkeit bei der Bestimmung verschiedener Eigenschaften wie z.B. hydraulische Leitfähigkeit. Eine Prozedur, welche Befestigung und nachfolgendes Einbetten von Ton partikeln in ein Epoxyharz umfasst, wird beschrieben. Dieses Verfahren macht die Observierung von Querschnitten von Tontaktoiden unter einem Trans parenzelektronenmikroskop und die Bestimmung der Anzahl von Tafeln per Taktoid möglich. Der Gebrauch dieser Prozedur für die Bestimmung des Verhältnisses zwischen dem austauschbaren-Natrium-Prozentsatz (ESP) und der Taktoid größe in Suspensionen eines Na/Ca Bentoniten wird presentiert.Es wurde demonstriert, daß sogar bei einem ESP- Wert von 5, schon Dispersion stattfindet. Die durchschnittliche Anzahl von Tafeln per Taktoid ist 6,6 verglichen mit 16,1 für einen ESP Wert von 0.

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Authors and Affiliations

  1. Institute of Soils and Water, Agricultural Research Organization The Volcani Center, POB 6, Bet Dagan, Israel

    I. Shomer & U. Mingelgrin

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  1. I. Shomer
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  2. U. Mingelgrin
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Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. 1977 Series. No. 199-E.

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Shomer, I., Mingelgrin, U. A Direct Procedure for Determining the number of Plates in Tactoids of Smectites: The Na/Ca-Montmorillonite Case. Clays Clay Miner. 26, 135–138 (1978). https://doi.org/10.1346/CCMN.1978.0260208

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  • DOI: https://doi.org/10.1346/CCMN.1978.0260208

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