EURO-ECO 2010 Hanover 2 - 3 Dezember 2010	Environmental, Engineering - Economic and Legal Aspects for Sustainable Living
	European Academy of Natural Sciences, Hanover European Scientific Society, Hanover University of Bremen, Bremen

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In the literature the data on change of colloidal-chemical characteristics of clay minerals both at thermal treatment and sorption of dyes from water solution with various concentration, practically lack. In the present work an effect of thermal treatment and change of pH medium at different concentrations of methylene blue (MB) on colloidal-chemical properties of Dash-Salakhly (DB) and its some monocation substituted forms has been studied. In the work on a case of DB bentonite and its some monocation substituted forms there were summarized the experimental results on a change of colloidal-chemical characteristics in the indicated specimens occurred at thermal treatment till 600°C. The results of the effect of colloidal-chemical properties obtained at sorption of MB from water solutions on the sorbents under study are cited. Sorption of MB on DB and its investigated monocation substituted forms have been studied in static conditions by the method of verbal concentrations. In the method of the verbal concentrations the definite hinge of bentonite samples (0,5 g) calculating on absolutely dry substance, was placed into the retort with volume (V=50 ml) of MB solution of various concentration correspondingly. the results of experimental studies show that thermally treated at 200°C DB and its Na, K, Ba, Al and Fe(III) forms manifest the maximum sorption capacity on MB in comparison with the specimens, thermally treated at temperatures of 105 and 400°C .

The increased adsorption capacity by MB at the temperature 200°C of the modified samples, for Al-DB – 102,3 mg/g, for Fe(III)-DB – 104,8 mg/g is connected with that with increase of the charge and ion radius of exchange cations dispersity and hydratation of the modified monocation forms decreases and the forces of electrostatic attraction between two- and free charge exchange cations and a molecule of one charge cation active dye increases. But the original bentonite in the consequence of polycation and great hydration properties of exchange cations is less accessible to substitution for MB cations and possesses low adsorption capacity.

At increasing temperature of activity (400°C) there is formed the tough crystalline structure and mechanical durability of the samples as a result of what the samples loose their ability of swelling. And it makes difficult penetration of molecules of MB into interplane space of the sorbents and leads to decrease of adsorption capacity on dye.

Na- and K-forms of bentonite behave other wise on MB by their sorption relations. With the increase of temperature till 400°C their adsorption activity on MB increases and then falls what is connected with decrease of their colloidal fractions. As the experimental results show the lesser colloidal fractions and deposit volume in bentonite dispersions the greater is adsorption activity on MB. It is established that at increase of treatment temperature of bentonite samples lessening colloidal fractions takes place. Thus, for instance, the contentent of colloidal fraction of original bentonite with an increase of treatment temperature decreases considerably less in comparison with its monocation forms what is related not to nature and charge of exchange cations, but also to polycation property of original bentonite. Diminition of the content of colloidal fractions of bentonite specimens at transit from a low temperature (105°C) to the highest ones (200, 400 and 600°C) may be explained by a change of partically crystalline structure and mechanical durability. It is established that an effect of sorption purification of sewage from cation dyes also depends on the conditions of formation of the dyes. In addition, their chemical nature influences essentially on a value of sorption of the dyes as well.