Sorption of Cobalt and Methylene Blue Ions by Montmorillonite-Silica Nanocomposites
Background. Deterioration of ecological state of water resources due to increasing content of inorganic and organic toxicants causes the development of scientific research in the direction of sorption materials synthesis, that have improved sorption capacity and selectivity. One of the promising methods for sorbents’ synthesis is the modification of layered silicates, the use of which is restrained by difficulties in separation of latter from the liquid phase.
Objective. The aim of the paper is a synthesis of nanocomposites, based on montmorillonite and sodium silicate, study of structure formation features in such systems and sorption properties of the obtained granular materials in relation to heavy metals and organic dyes.
Methods. Research of structure formation features in the initial systems by the methods of rheometry and X-ray phase analysis. Condition investigation for the nanocomposites synthesis. Relationship establishment between composition in the initial systems and sorption properties.
Results. The structure formation features in the initial water–montmorillonite–silicate systems are studied, the effect of sodium silicate concentration on the rheological properties of the dispersions is established. The effect of the initial system composition on the porous structure of synthesized materials and their sorption properties to remove the cobalt (II) and methylene blue from aqueous solutions is shown.Conclusions. It was found that the limiting shear stress and plastic viscosity dependence of the montmorillonite–sodium silicate solution system has an extreme character (extremum at 0.1–1 % SiO2 content), which is associated with the transition of coagulation contacts into crystallization contacts due to siloxane bonds formation. It has been experimentally confirmed, that an increase in the content of montmorillonite in the obtained materials improves their sorption capacity (up to 450 μmol/g) to the cobalt (II) and methylene blue removal.
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