S. V. Bondarenko

Interaction of Water and Methanol Molecules with the Surface of Carbonaceous Materials According to Gas Chromatographic Data

We have used gas chromatography to study the interaction of water and methanol molecules with active hydrophilic centers on the surface of thermally expanded graphite and graphitized thermal carbon black. We have determined the concentration of carboxyl and phenol hydroxyl groups on the surface of the sorbents and the heats of adsorption for adsorption of the studied substances on these groups. We have shown that water molecules are adsorbed as clusters on the hydrophilic centers of the studied sorbents at very low relative pressures, with n = 2 molecules in the cluster.

Absorption of organic anions from aqueous solutions by layer silicates substituted with a cationic electrolyte

The paper has conducted adsorption and spectral research of interaction of organic dyes of anionic nature with the substituted cationic polyelectrolyte (hydrochloride polyhexamethylene guanidine) layer silicates (kaolinite and hydromica). It has been proved that modifying results in an increased adsorption capacity of minerals to organic anions owing to the formation of the sorbent surface of the sorbate/modifier ionic associates. Selectivity of the sorbents being investigated to anionic compounds increases with an increase of hydrophobicity of the latter.

Adsorption of organic anions from aqueous solutions by layered silicates modified with cationic surfactant

The interaction of anionic organic dyes with layered silicates (kaolinite and hydromica) both natural and modified with a cationic surfactant (cetylpyridinium bromide) is studied by adsorption and spectral methods. The adsorption of organic anions by modified silicates is proved to proceed via the formation of ionic associates of these adsorbates with the modifier. It is found that the interaction of large organic anions with the modifier results in the desorption of the latter, followed by its secondary adsorption in the form of ionic associates with the adsorbates. The selectivity of layered silicates modified with the cationic surfactant to organic anionic dyes is determined by the stability of the formed dye/modifier ionic associates and their affinity to the surface. These factors depend on the sizes of the hydrocarbon moieties of both components of the associates. Therefore, the selection of a suitable modifier allows one to control the selectivity of modified minerals to different organic anions. Using long-chain organic cations as modifiers, organic anions of any sizes can be extracted from aqueous solutions.

Interaction between crystal violet and natural and organic cation-modified layered silicates

Adsorption and spectral methods are employed for complex studying the interaction of organic cations of crystal violet with layered silicates, kaolinite and hydromica, both natural and modified with a cationic surfactant, cetylpyridinium bromide, and a cationic polyelectrolyte, poly(hexamethyleneguanidine hydrochloride). It is shown that, on the surface of silicates modified with long-chain cationic surfactants, the examined sorbate is sorbed via the hydrophobic interaction of its aggregates with the modified surface. In the case of minerals modified with relatively hydrophilic poly(hexamethyleneguanidine hydrochloride), crystal violet cations are sorbed through the ion-exchange mechanism by displacing the functional groups of the modifier from the surface.

Production and structural-sorption properties of alumosilicates with a hard structural cell modified with polyelectrolyte

We have developed a method of modifying layer silicates with cationic polyelectrolyte-hydrochloride polyhexamethyl guanidine. Using samples of layer silicates with a hard structured cell (kaolinite and hydromica) we realized the proposed method of modification. It was shown that at a sharp decrease of hydrophilicity modification, for all intents and purposes, does not lead to additional aggregation of the particles in drying the materials, which manifests itself in retaining their main structural-sorption characteristics by the data of adsorption of nitrogen and n-hexane compared with initial samples. This creates conditions for effective use of thus prepared sorbents in purifying aqueous media of pollutants.

Structure-sorption properties of natural layer silicates and layer silicates modified by cationic SAS with a rigid structural cell

We have obtained sorbents modified by the cationic SAS based on hydromica and kaolinite—layer silicates with a rigid structural cell. We have studied structure—sorption properties of initial and developed materials. It has been shown that modification results in a sharp decrease of hydrophilicity of minerals, enhancement of their affinity to the molecules of anionic and nonionogenic SAS. We have noted a substantial increase of sorption capacity of modified minerals with respect to nonionogenic SAS, which is explained by the formation on the surface of the sorbent of bulk associates from the molecules of cationic and nonionogenic SAS.

The structure of modifying layers and identification of residual hydrophilic groups on modified silica surface by the adsorption and chromatographic measurements

Amorphous silica Silochrom-80 is modified in a liquid phase in two stages with poly(ethylhydrosiloxane) and hexamethyldisilazane. Adsorption studies suggest that the modified silicas have a porous structure. Hexamethyldisilazane is found to have an active role in the modification of the secondary porous structure of the samples. The thickness of modifying layers on the surface of the samples is calculated. Residual hydrophilic sites are identified on the modified silica surface, and their concentration is determined using chromatography data and the parameters of the Langmuir equation. It is shown that the two-stage modification of silica with the selected reagents makes it possible to entirely deactivate the most active vicinal hydroxyl groups on the sorbent surface and, to a substantial extent, its isolated hydroxyl groups.

The study of the structural, sorption, and electrochemical properties of a natural composite shungite

AbstractAn integrated study of the structural, sorption, and electrochemical properties of a natural mineral shungite has been carried out. The composite nature of the mineral has been shown to predetermine its basic physicochemical characteristics. The isosteric heat of water adsorption

Hydrophilic sites on silica surface modified in gaseous and liquid phases

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