ИСТИНА

There are plenty of organic pollutants that are dangerous for aqueous and aerial environment. The traditional method of separation is mechanical filtration. Due to their porosity and tunable physicochemical characteristics carbon nanomaterials with various types of structure have several advantages as filtrating materials [1]. The possibility of introducing heteroatoms in graphene layers can improve the selectivity of adsorption of desirable pollutants [2]. The aim of this work was to detrmine the heat of sorption of acetone, etylacetate and toluene on carbon nanomaterials surface as well as nitrogen-doped ones. Two types of carbon structures were selected: carbon nanotubes (CNT) and carbon nanoflakes (CNF). Carbon nanomaterials were obtained by pyrolysis of benzene (pristine CNT and CNF) and acetonitrile (N- CNT and N- CNF). Adsorption properties of nitrogen-doped carbon nanostructured powders as well as pellets, obtained by spark plasma sintering method, respective to ethanol, acetonitrile, heptane, benzene, water and 1-methylimidazole were studied by DVS Advantage instrument (SMS, UK).Experimental heats of sorption of all the solvents on carbon nanomaterials’ surfaces were calculated according to: ∆H_s=-R ln⁡(p_2/p_1 )/(1/T_2 -1/T_1 ) , after measurements at 20 и 30 С. Organic vapour sorption measurements are compared to liquid nitrogen sorption data. Thermal analysis was performed to determine amorphous carbon and noncombustible residue content. Composition and chemical state of N atoms of CNTs and CNF surface was identified by XPS method. The specific surface area calculated from organic vapour sorption appears to be in agreement with that calculated from liquid nitrogen adsorption measurements for all tested materials. The values of the heat of acetone adsorption were found to be -34,1, -33,5, -35,8 kJ/mol on CNT, N-CNT, N-CNF respectively although on pristine CNF - -38,4 kJ/mol. It was found that heat of adsorption values are affected by effective molecular areas of adsorbate, their dipole moments as well as carbon nanomaterials morfology. CNF have the largest surface area and are presumably the best adsorbents for polar substances. CNTs are the most suitable for toluene adsorption among all studied materials