Physical and Chemical Foundations of the Technology for Obtaining Sorbents from Coals by Activation with Potassium Hydroxide
G. R. MONGUSH1, M. P. BARANOVA2,3, T. V. SAPELKINA1
1Tuvinian Institute for Exploration of Natural Resources, Siberian Branch of the Russian Academy of Sciences, Kyzyl, Russia
2Siberian Federal University, Krasnoyarsk, Russia
3Krasnoyarsk Agrarian University, Krasnoyarsk, Russia
Keywords: coal, carbonization, sorbents, specific surface area, pore volume, potassium hydroxide
Pages: 513-521
Abstract
Carbon sorbents were obtained at different ratios of coal/alkali from coals of the Kaa-Khem, the Mezhegey and the Elegest deposits. It is established that the necessary mass ratio of coal/alkali for these coal samples at the activation stage is 1 : 3 or 1 : 4. The excess alkali concentration worsens textural characteristics. It is shown by means of IR spectroscopy and thermogravimetry that alkaline treatment causes chemical changes in the molecular structure: the content of oxygen-containing fragments increases, the amount of carbon in aromatic structures decreases, which causes a decrease in caking capacity. The revealed features include a significant decrease in the final temperature and narrowing of the interval of the main decomposition of the coal organic mass, changes in the mass loss curves within the temperature range of 500-750 °C, corresponding to the zone of decomposition of the aromatic structures in coal. Physicochemical regularities of material formation and optimal conditions providing the production of sorbents with high texture characteristics from sintering coals were determined. On the basis of the studies of adsorption characteristics of the samples (for iodine and methylene blue), it is concluded that it is reasonable to use the obtained carbon sorbents for the purification of industrial wastewater from organic pollutants (phenol, pyridine, etc.).
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