Sorption of copper ions from water by bentonite clays
V.A. Somin, L.V. Kurtukova, L.F. Komarova
Section: Ecologization of industry
The traditional method of removing metal compounds from water is sorption, based on the use of various materials of both natural and artificial origin, which must be available, have high mechanical strength, the ability to regenerate multiple times, and resistance to aggressive environments. An important role in choosing a sorbent is played by selectivity and the value of the maximum sorption, the determination of which is carried out experimentally. Sorbents of natural origin include bentonite clays, which were studied by the authors in these studies. The results of studies on the sorption of copper ions on bentonite clays of the Desyaty Khutor deposit (Khakassia) grades 5.1 and 6.9 are presented. Native bentonite of both grades was washed with distilled water to remove large impurities, after which the suspension was settled and separated by density into a lower and upper layer. The layers were separated, then they were activated with a 5% solution of sodium bicarbonate. After that, the obtained activated bentonites of each grade were dried to a constant weight at a temperature of 105 оС. It was revealed that the bentonite layers exhibit different copper sorption abilities and are characterized by different nature of the processes occurring on them. The studies were carried out on model copper sulfate solutions. It was revealed that soda activation increases the sorption capacity of native bentonite grade 5.1 by 1.6 times (from 50 to 80 mg/g) for the upper layer and by 1.1 times for the lower layer. The sorption process is satisfactorily described by the Langmuir and Freundlich models for both native and modified bentonites, the Dubinin-Radushkevich model adequately describes sorption only on modified materials. Sorption of copper ions on the native sorbent and the activated lower layer is characterized as physical, while the chemisorption process occurs on the activated upper layer. The sorption capacity of bentonite activated by sodium hydroxide (upper layer) is 81–84 mg/g, which allows it to be used in the purification of copper-containing wastewater and thereby reduce the negative impact on surface water bodies.
Keywords: sorption, copper ions, bentonite clays, water treatment, pollution, heavy metals
Article published in number 4 for 2025 DOI: 10.25750/1995-4301-2025-4-130-139
ISSN 1995-4301
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