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Προσδιορισμός της προσροφητικής ικανότητας μπεντονιτών με τις μεθόδους της κεραμικής πλάκας και του κυανού του μεθυλενίου

Grypaiou-Iskenteridou Georgia

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Summary

The purpose of the present Thesis is the examination and study of the mineralogical composition through X-ray diffractometer (XRD) of 28 bentonite samples from different regions of which are Milos, India, South Africa and the USA. These samples were first subjected to drying and pulverization in powder form and then analyzed mineralogically through X-ray diffraction (XRD) as well as qualitative and quantitative determination of clay minerals. The quantitative analysis is carried out to obtain percentages of clay minerals in either the bulk rock or the clay fraction. Up to 16 different minerals were identified, of which the main component is smectite (montmorillonite) with a content of 95,9 % to 52,4 %. There are also minerals of the plagioclase group (albite), silica (quartz), potassium feldspar (sanidite, microcline), carbonate minerals (calcite), mica (muscovite, illite, biotite), clinoptinolite (zeolite), jarosite, gypsum, cristobalite, pyrite and halite.Furthermore, this Thesis presents the experimental results of the laboratory analyses, which aim to characterize the tested samples and to study their adsorptive capacity through the ceramic plate method, in order to determine the ability of bentonite samples to adsorb water, following the porous plate adsorption-absorption method (plate test). This method worked correctly and it was found that sodium samples display a very high water adsorption capacity compared to calcium bentonite samples. The Na-activated samples also showed high water adsorption capacity, while the samples heated at 550o C failed to adsorb water.Finally, the methylene blue method was applied to the same samples in which the determination and estimation of the cation exchange capacity of bentonite was examined. This was achieved by measuring the absorbance of methylene blue relative to dry bentonite (ml). Methylene blue absorption was observed for most samples except those heated at 550o C which failed to absorb more than 2 ml of methylene blue. A different behavior was observed by the USA Kinney sample which absorbed 31 ml of methylene blue while in the ceramic plate experiment it did not adsorb enough water, although it has smectite content of 95.9%.

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