Concentrating And Separating Of Al(iii), Ga(iii) And In(iii) By Their Sorption On Amorphous Silicas
CONCENTRATING AND SEPARATING OF AL(III), GA(III) AND IN(III) BY THEIR SORPTION ON AMORPHOUS SILICAS
A. N. Chebotaryov, E. M. Rakhlitskaya, A. N. Zakhariya
I.I. Mechnikov Odessa State University, Department of Analytical Chemistry, Odessa, Ukraine
For the purpose of the selective separation of Al(III), Ga(III) and In(III) microquantities, physico-chemical regularities of the adsorption extraction and separating of the analogue-elements, using amorphous silicas, in particular A-300 aerosil and K-7-30, its analogue modified by dimethylchlorosilane, were studied within a wide range of pH value. As shown by the example of A-300, the degree of adsorption extraction depends on acid-base characteristics of the heterogeneous sorbate-sorbent system. The same type of the curves in S vs. pH plot obtained for Al, Ga and In is evidence of the similarity in the sorption behavior of A-300 aerosil with respect to these metals.
The study of the dependence of the degree of Al, Ga and In extraction by modified K-7-30 aerosil on pH of the medium has shown that the absence of their sorption in acid medium and the gradual increase in the extraction percentage with the growth of pH value is characteristic of all these metals. The beginning of In, Ga and Al sorption corresponds to pH 2, 3 and 5 while the maximal extraction – to pH 5, 7 and 8, respectively. These regularities can be interpreted on the basis of the non-uniform sorbate model proceeding from the state of sorbent surface groups and the degree of hydrolysis of the studied metal ions in the process of the medium acidity changing.
The influence of ethanol on the sorption interaction process has been confirmed.
On the basis of the isotherms obtained, the mechanism of adsorption of these metals on amorphous silicas has been suggested. The data of the study were applied for the determination of the optimal conditions for Al, Ga and In concentrating and separating.
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