Effect of chemical modification on the structural characteristics and adsorption properties of bentonite from the Navbahor deposit

The results of a study of montmorillonite-containing bentonite clays from the Navbahor deposit (Navoi region, Uzbekistan) of two types: alkaline (B1) and alkaline earth (B2).X-ray diffraction analysis, electron microscopy, thermal analysis (TGA/DTGA/DSC), and spectral methods were used to clarify the phase composition and thermal behavior; differences in the position and shape of endothermic effects and in the stages of mass loss are demonstrated.Composite forms (FB1, FB2, KB1, KB2) were obtained based on ionic modification with Fe 3+ -Mg 2+ -Mn 2+ and Ca 2+ -Zn 2+ -Mn 2+ salt systems; the synthesis procedure included pH adjustment (9-11), aging, washing until the absence of Cl⁻, drying, and heat treatment at 300°C, which reduces swelling and facilitates the separation of the solid phase.According to X-ray diffraction data, changes in the interlayer distance of montmorillonite and signs of the formation of oxide phases were noted; according to low-temperature nitrogen adsorption, an increase in the specific surface area was recorded (the maximum value for KB1 was 146.1 m 2 /g).Adsorption tests for Cu 2+ and PO 4 3-(CO = 200 mg/l, pH 6.9) demonstrate acceleration of kinetics and increase in sorption capacity of modified samples compared to the original ones (OB1, OB2), with the highest activity characteristic of FB1.The obtained data confirm the potential of modified bentonites as accessible sorbents for the removal of inorganic pollutants from aquatic environments

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