Studying the structure and properties of sorption materials made on the basis of modified bentonite

The results of comparing the structure and chemical composition of two modifications of bentonite (modified with carbon nanotubes, granulated and fired at a temperature of 550 °C and granulated, fired at a temperature of 550 °C and hydrophobized) are given in the article. In the work, bentonite with a granule size of 0.1 ... 1.0 mm was used. The results of scanning electron microscopy of the surface of bentonite granules of both studied modifications were studied before and after the adsorption of Fe2+ and Cu2+ ions. After passing model solutions of CuSO4.5H2O and FeSO4.7H2O through the sorbents at a significant magnification, it was observed that the surface of the granules is partially covered with foreign inclusions (inclusions), which are visible at a significant magnification and look quite contrasting with respect to the surface of the sorbent granules. The chemical composition of the samples of the studied sorption materials was obtained using an energy-dispersive spectrometer built into a scanning electron microscope. A comparative analysis of the chemical composition of the surfaces of particles of both modifications of bentonite showed that before passing through them model solutions, bentonite with carbon nanotubes contains a larger amount of carbon, and hydrophobized bentonite contains a larger amount of oxygen. In both samples, silicon is the predominant element in the structure, aluminum, carbon, and oxygen make up a smaller proportion, and even less is calcium. A small proportion are metals - magnesium, sodium, calcium, iron, potassium. An analysis of the chemical composition of the surfaces of bentonite samples of both modifications subjected to sorption showed the presence on the surface of the sorbents of a significant amount of chemical elements: iron and copper, which confirms the adsorption capacity of these materials. Laboratory studies have established the basic mechanical and physical properties of bentonites of both modifications. The experimentally established highest adsorption values of heavy metal ions Fe2+ and Cu2+ on granular bentonite, fired at a temperature of 550 °C and hydrophobized, characterized by a sufficiently high specific surface area, make it possible to recommend this modification of bentonite as an effective sorption material for water purification from Fe2+ and Cu2+ ions.