Abstract
Montmorillonite has high cation exchange capacity and can be used as a sorbent for the removal of metal cations. But anions adsorption on the surface of the mineral is limited. Targeted regulation of hydrophobic and hydrophilic surface properties using sorbents provides an opportunity to increase its absorption properties in relation to anions. The results show that the degree of Cr(VI) extraction by the sorbents obtained at montmorillonite modification increases with increase of CEC/S. Organoclays that modified at CEC/s 1 showed higher adsorption capacity in relation to Cr(VI), but a part of HDTMA isn’t related to the mineral surface and involved in the removal of Cr(VI) from solution with precipitation in the form of alkyl ammonium chromate. HDTMA in free form is harmful to the environment, so CEC/S for these sorbents must not exceed 1. Adsorption of Cr(VI) compounds essentially depends on pH of a solution. The highest values are obtained at pH from 1 to 6. Adsorption properties of organoclays are decreased at pH 6 to 8. Removal of Cr(VI) is not significant in the alkaline environment. These studies will form the basis for the study of structural and mechanical properties of organoclays to use their suspensions for removal of anions of heavy metals and radionuclides using the latest environmental technologies directly from the soil layers.
Highlights
Chromium in aquatic systems may be mainly in the form of Cr (III) and Cr (VI) [1]
Their removing from aquatic environments is complicated by the fact that chromates are soluble at all pH values, and they are not absorbed by the minerals of aquifers due to a negative
Interlayer cations of clay minerals are displaced by quaternary ammonium cations that can displace Na+ ions from the ion-exchange positions in montmorillonite, increase of the number of hydrocarbon atoms in nonpolar aliphatic group contributes to a more efficient displacement of interlayer cations
Summary
Chromium in aquatic systems may be mainly in the form of Cr (III) and Cr (VI) [1]. Compounds of Cr (VI). Their removing from aquatic environments is complicated by the fact that chromates are soluble at all pH values, and they are not absorbed by the minerals of aquifers due to a negative. Membrane filtration, ion exchange chromatography, dialysis/electrodialysis, reverse osmosis and adsorption are usually used for removal of Cr(VI) from aquatic environment. These methods have many disadvantages, such as incomplete removal of metal, high cost of the reagents, a necessity for large amounts of energy, creation of the toxic sludge and other wastes that require further purification. The relevance of the article is due to the need to improve modern highly efficient sorbents and technology solutions for their application for the removal of heavy metals and radionuclides from aquatic environments
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