The COMPARISON OF SORPTION PROPERTIES OF SILICON-CARBON ADSORBENTS SYNTHESIZED BY VARIOUS METHODS

Abstract

Siliconoxycarbon adsorbent was synthesized by mechanochemical activation of activated carbon BAU and by sol-gel technology by deposition of sodium metasilicate on the surface of coal, followed by drying and calcination of the samples and tetraethoxysilane to remove the solvent. To study the morphology of adsorbent particles, the method of scanning electron microscopy was used, according to which the nature of the interaction of activated carbon with sodium metasilicate and tetraethoxysilane was judged. Mechanochemically modified activated carbon is a fine powder: both large crystal-like particles and small shapeless ones are visible. During the joint mechanical treatment of activated carbon and white soot, agglomerates of amorphous white soot are noted, which are layered on activated carbon particles. The adsorbent obtained by the sol-gel method has large clusters of amorphous silicon dioxide covering the coal particles, almost completely "hiding" them. The results of studies of silicon oxycarbon adsorbents by infrared spectroscopy indicate the appearance of absorption bands characteristic of vibrations of Si-O-C bonds. For the sol-gel method, the absorption bands are more diffuse. Using the resulting composite as an adsorbent, studies were carried out on the efficiency of extraction of the thiazine dye methylene blue from aqueous solutions and defluorination of extractive phosphoric acid. For the mathematical description of the adsorption process, traditional models of adsorption kinetics (pseudo-first and pseudo-second orders) were applied. It has been established that the presence of silicon-containing compounds reduces the defluorination temperature by increasing the proportion of SiF4 in gaseous products. This allows you to increase productivity and reduce energy costs for defluorination.