The effect of various factors on micro-analysis by circular thin-layer chromatography

Summary The effect of various factors such as thickness of layer, acidity, activation of layer, amount of sample spotted, time interval for the flow of solvent, saturation of developing chamber, etc. have been studied using circular TLC apparatus and suitable conditions for micro-analysis by circular thin-layer chromatography are recorded. Comparative study with linear TLC is made to evaluate advantages of circular TLC in microanalysis.

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Zusammenfassung Der Einfluß der Schichtdicke, der Acidität, der Aktivierung des Schichtmaterials, der aufgetragenen Probenmenge, der Dauer des Lösungsmittelflusses, der Sättigung der Kammeratmosphäre usw. auf die Dünnschicht Ringchromatographie wurde geprüft und geeignete Arbeitsbedingungen ausgearbeitet. Im Vergleich zur linearen DC wurden die Vorteile hervorgehoben.

     

Analysis of ores by simple grinding and circular thin-layer chromatography and the nichrome wire ring chamber

Summary A method for the preparation of ore solutions by grinding the ore with distilled water is developed for the analysis of minerals and ores in the field by the circular thin-layer Chromatographic technique.

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Zusammenfassung Die Herstellung von Erzlösungen durch Mahlen des Erzes mit dest. Wasser zur Feldanalyse von Mineralen und Erzen durch Ring-Dünnschichtchromatographie wird empfohlen.

     

Sorption of cobalt on bentonite

Sorption of Co on bentonite has been studied by using a batch technique. Distribution coefficients (K _d ) were determined for the bentonite-cobalt solution system as a function of contact time, pH, sorbent and sorbate concentration and temperature. Sorption data have been interpreted in terms of Freundlich, Langmuir and Dubinin-Radushkevich equations. Thermodynamic parameters for the sorption system have been determined at three different temperatures. The positive value of the heat of sorption, H ⁰=22.08 kJ/mol at 298 K shows that the sorption of cobalt on bentonite is endothermic, where as the negative value of the free energy of sorption, G ⁰=–10.75 kJ/mol at 298 K shows the spontaneity of the process. G ⁰ becomes more negative with an increase in temperature which shows that the sorption process is more favourable at higher temperatures. The mean free energyE7.7 kJ/mol for sorption of cobalt on bentonite shows that ion-exchange is the predominant mode of sorption in the concentration range of the metal studied i.e. 0.01 to 0.3 mol/dm³. The presence of some complementary cations depress the sorption of cobalt on bentonite in the order of K⁺>Ca²⁺>Mg²⁺>Na⁺. Some organic complexing agents and natural ligands also affect the sorption of cobalt. The desorption studies with ground water at low cobalt loadings on bentonite show that about 97% metal is irreversibly sorbed.