The exchange of Na+ ions of vermiculite for Co2+ cations is measured by sorption-analytical and microcalorimetric methods. The previously revealed growth of the equilibrium constant with a rise in the degree of filling θ of vermiculite exchange sites with Co2+ cations is confirmed. This result is explained by the segregation of Co2+ and Na+ cations being exchanged in separate interlayer regions of vermiculite. The negative heats of exchange of Na+ cations for Co2+ cations are associated with the energy consumption for the rearrangement of the segregated interlayer regions in vermiculite. The positive entropy changes resulting from the exchange indicate the formation of a more disordered Co-Na-layered “cake” in comparison with the initial Na-form vermiculite. A decrease in the integral molal free-energy change ΔG m of the mixed form of the mineral is determined by the entropy factor. It is shown that, as θ increases, the ΔG m(θ) dependence passes from a positive to a negative range of values. This pattern of the curve may be interpreted as a gradual phase transition from the Na-form to the mixed Co-Na-segregated form. The first derivatives of the enthalpy and entropy changes with respect to the degree of filling θ exhibit distinct maxima at θ ∼ 0.20 as a result of the transition from the ideal mixing of Co2+ and Na+ cations being exchanged to their segregation.

The article gives a simplified model of water deironization on a filtering medium from natural clinoptilolite based on the results of pilot research and industrial tests. Advantages and disadvantages of the model were found. The possibilities of using this model have been shown in optimization of the water demanganization on natural modified clinoptilolite.

The sorption of cetylpyridinium on Na-vermiculite has been studied by the adsorption, calorimetry, and X-ray diffraction methods. The ion-exchange component of cetylpyridinium sorption on Na-vermiculite has been distinguished and analyzed. Variations in the integral heat of ion exchange of cetylpyridinium cations on Na-vermiculite have been determined as depending on the amount of absorbed cetylpyridinium by the calorimetry method. X-ray diffraction analysis of cetylpyridinium-Na-vermiculite organomineral complexes with different contents of exchange cations has been carried out in parallel. The formation of monolayer (interlayer spacing Δ d = 20.25 Å) and bilayer (Δ d = 37.27 Å) intercalation structures with a tilt angle of cetylpyridinium ions to the silicate basal surface of ≈57° has been revealed.

The exchange of Co2+ ions on Na-vermiculite has been comprehensively studied by the ionexchange, adsorption, and X-ray diffraction methods. It has been shown that vermiculite is distinguished by high selectivity to Co2+ cations and Kielland dependence log \(\tilde K_m (\theta )\) increasing with filling of ion-exchange sites with sorbed cations rather than a decreasing one that is observed for common systems. It has been established that the ion exchange is accompanied by segregation of Na+ and Co2+ cations in separate interlayer gaps of vermiculite with the final formation of a disordered layered “cake” composed of separate silicate layers and interlayer gaps enriched with Na+ and Co2+ ions.

The isotherms and differential heats of water vapor adsorption on kaolinite modified with poly(hexamethylene guanidine) hydrochloride are measured. Modification efficiency is, to a high extent, determined by the compliance (complementarity) between the structure of the modifying agent and the chemical nature of the kaolinite surface. It is shown that the individual stages of the interaction between water and the modified sorbent comprise sorption of four or five molecules on triads of amino groups of the modifying layer, conformational changes in the layer, the formation of additional adsorption sites, partial rupture of the modifying layer, and the dispersion of kaolinite particles induced by adsorbed water. Alternative opinions are presented on the reason for the appearance of the additional adsorption sites. It is proven that not only the adsorbate, but also the adsorbent, undergoes efficient changes during the adsorption.

A method and technology for the deposition of strongly bonded high-disperse manganese dioxide onto the external surface of clinoptilolite grains is developed. The optimal conditions for the application of thus prepared material for the purification of artesian water are determined. A two-stage process of water purification is proposed, which involves usual clinoptilolite filter at the first stage to remove the main amount of iron, and the filter with modified clinoptilolite on the second stage to remove the residual iron and bivalent manganese ions. The proposed technology of preparation and application of modified clinoptilolite is tested in industrial conditions.

The isotherms and differential heats of water vapor adsorption on Na- and Ca-saponite samples are measured. It is shown that the successive stages of hydration of the internal surface of this mineral appear as waves or inflections in the adsorption isotherms and maxima in the dependences of the differential heat on the adsorption value. The compositions of Na + and Ca 2+ aquacations in single- and double-layer saponite hydrates are determined. The heats of interaction between water molecules and interlayer Na + cations in single-layer saponite hydrates and between Na + cations and the ion exchanger matrix are estimated.

We have investigated the ion-exchange sorption of cations of alkaline metals on saponite at the constant and varied ionic force. We have determined a selectivity series of exchange centers of saponite with respect to these cations. It has been shown that the exchange centers on the saponite surface are unequal in terms of energy. When using the Langmuir equation two types of energy centers sharply different by energy; these centers were referred to specific sections of the saponite structure.

We have investigated adsorption isotherms of water vapors and heat of the wetting by water of a number of saponite samples with alkali, alkaline-earth and transition 3d-cations in the exchange complex. It has been shown that in a single-layer hydrates of a mineral of thickness Δ d = 2.8–3.2 Å the formation of flat di-, tri-, and tetra-aquacations of metals takes place. In two-layer hydrates doubly charged exchange cations, as a rule, are surrounded by the octahedral of water molecules. Thermal stability of interlayer hydrates are small: they are destroyed as a result of thermovacuum treatment at 140°C. A decrease of the water heat wetting of the samples with transition metal ions in the exchange complex after thermovacuum treatment at 300°C is related to the irreversible merging of a part of the saponite structural layers as a result of the formation in interlayer intervals of waterless oxides of transition metals. The paper noted the ways of using saponite as an active supplement to the coagulant for increasing the quality of natural water treatment.

Sorption-analytic studies of ion exchange equilibria combined with direct calorimetric measurements of the heats of ion exchange sorption of the Ca2+, Sr2+, and Ba2+ cations were performed over the whole range of solid phase fillings with sorbed cations on the Na forms of two mordenites prepared from natural specimens rich in Na+ and Ca2+ cations. Ion exchange constants were determined and the Gibbs energies and entropies of ion exchange were calculated. The thermodynamic characteristics obtained were analyzed taking into account the preferable localization of alkaline-earth metal ions on certain exchange centers in the structure of mordenite. The presence of natural mordenite memory effects with respect to extra-framework Ca2+ cations in the presence of which these zeolites were crystallized in nature was established.

It was shown, by ab initio calculations of the characteristics of hydrophilic centers formed on the surfaces of organosubstituted kaolinites with equivalent and superequivalent modifications, that superequivalent modifications of the mineral surface with octadecylammonium chloride, i.e. blocking the hydrophilic centers of the ionic-adsorbed cationic surface-active substance with the molecular adsorbed amine, led to the redistribution of the electron density close to these centers, in particular to the decrease in the effective charge at the hydrophilic centers. The calculated structures and energetics of nanostructures formed by the adsorption of water molecules at such hydrophilic centers showed that such redistribution decreases the energy of their interaction with water, which resulted from theoretical decrease in the energetic effects of hydration of the centers effectively agreed with the experimental values of the heats of adsorption. It was shown that for such adsorbtion systems the energetics were suitable for the formation in the region of the adsorption centers of cyclic structures of water.

The molecular statistical method for evaluating the distribution of active sites of various adsorbents relative to their energies has been improved. This method is used not only for the treatment of experimental data on the adsorption of hydrocarbons on various adsorbents, which is the usual procedure, but also data on the adsorption of polar water and methanol molecules on the active sites of adsorbent surfaces. Two types of active sites differing in energy have been shown to exist on the surface of graphitized carbon black, the complex shungite carbon/mineral adsorbent, and modified Silochrom. Chromatographic, calorimetric, and structural adsorption data were used to establish the relationship between the observed maxima of the energy distribution function of the adsorption sites with concrete adsorption sites or pores of the surface, on which the molecules are adsorbed.

We have found optimal conditions for obtaining an effective sorbent—catalyst based on natural clinoptololite with chemosorbed manganese dioxide for removing Mn2+ ions from water. Using a complex of sorption-analytical, structure-sorption, electron-microscopic methods we have studied the properties of the modifying δ-MnO2-film. The mechanism of its sorption-catalytic effect on Mn2+ has been discussed.

An 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 \(\bar Q_a \) = 70 kJ/mol, as estimated by calorimetry and gas chromatography, reflects the interaction of its molecules with vicinal hydroxyl groups of the silica component of shungite. Adsorption heats, \(\bar Q_a \) = 40–45 kJ/mol, is governed by the carbon moiety of the sorbent. Higher adsorption heats of benzene on shungite, as compared with those of hexane, are indicative of the interaction of its molecules with active sites of the carbon and silica moieties of the mineral. The type and number of these sites have been determined by potentiometry and conductometry. The obtained adsorption parameters of shungite with respect to anionic organic compounds enable us to recommend its application as a sorbing material for filtration.

Direct calorimetric measurements were used to determine the heats of exchange of the Mn2+, Co2+, Cu2+, and Ni2+ cations on the Na form of clinoptilolite over the entire range of solid phase fillings with sorbed cations. In parallel, ion exchange isotherms for the systems were measured by the sorption-analytic method. The integral free energies and entropies of ion exchange were calculated. It was shown that the solution phase of the clinoptilolite-electrolyte solution two-phase system contributed significantly to the total thermodynamic characteristics of ion exchange. The differentiation of the dependence of the integral enthalpy on the degree of filling was performed to show that the clinoptilolite structure contained at least two types of exchange sites having different interaction energies with transition metal ions.

A concurrent absorption analytical study of the ion exchange equilibria and direct microcalorimetric measurement of the heat of ion exchange absorption of K + and Ca 2+ cations for the sodium forms of two mordenites (NaM) obtained from naturally occurring samples rich in Na + and Ca 2+ cations has been carried out for the first time. The free energies and entropies of exchange have been calculated. It was shown that the free energy of exchange in the K + -NaM system is determined by the enthalpy, whereas in the Ca 2+ -NaM system it is determined by the entropy of solvation. The measured thermodynamic characteristics of exchange were analyzed taking into account the preferred localization of sorption for the cations in the structure. A memory effect in natural mordenites has been established for extra-skeletal K + and Ca 2+ cations, in the presence of which these zeolites crystallized in nature.

Water adsorption on initial and modified Silochrom samples was studied by the adsorption calorimetry. Integral heats of immersional wetting by water were measured simultaneously. It was shown that hydroxyl groups both free and sterically screened by a modifier remain on the modified Silochrom surface. Concentrations of these groups and OH groups chemically interacted with the modifier were estimated. The heat of reaction of water molecules with a free surface OH groups of modified sorbents was determined (≈60 kJ/mol). It was found that the modifying layers of the sorbents are getting loose under the effect of adsorbed water, and water molecules gain access to the sterically screened OH groups; the heat of water interaction with these groups is 54–55 kJ/mol. The energy is consumed for getting the modifying layers loose and the rupture of point contacts between Aerosil particles of the secondary structure of both initial and modified Silochrom that significantly affects the heat of immersion, the differential heat of adsorption, the form of the heat release curve, and the dependence of the differential heat on the adsorption value.

The adsorption–calorimetric method is used to study the adsorption values and adsorption heats of benzene at the modified kaolinite and silica samples. The entropy diagrams of the benzene adsorbed at these samples are calculated. The results are compared with the entropy losses calculated from the ideal models of localised and non-localised adsorption. It is shown that the nature of the inorganic matrix, the modifier type and the modification degree determine the character of the benzene sorption on the studied sorbents, which can be described either by the supermobile model, non-localised model or non-localised model with partial loss of rotational degrees of freedom. For an infrequent case of supermobile adsorption of benzene at the modified silica, the frequencies of the vibrations of the molecule perpendicular to the surface are calculated.

Values and heats of benzene adsorption on modified kaolinite and silica samples are measured by adsorption calorimetry. Entropy diagrams are calculated for benzene adsorbed on these samples. Obtained results are compared to entropy losses theoretically calculated for benzene molecules using the models of ideal localized and nonlocalized adsorption. It is demonstrated that, depending on the type of an inorganic matrix, the nature of a modifier, and the degree of modification, the adsorption of benzene molecules on studied sorbents is described by the models of a supermobile nonlocalized adsorption or a nonlocalized adsorption accompanied by the loss of some rotational degrees of freedom. For a rare case of the supermobile adsorption of benzene on the modified silica, the vibration frequency of its molecules with respect to the surface is calculated.

The adsorption of methanol on initial silica and modified silica samples containing large mesopores is studied by the adsorption–calorimetric method. The grafted tridecylfluoroalkyl groups have a tilted orientation on the silica and physically screen the part of the surface OH groups that have not been involved in the reaction with a modifier. Adsorbed methanol makes the modifying layer looser, thus facilitating the accessibility of methanol molecules to these hydrophilic adsorption sites. Concentrations of OH groups involved in the chemical interaction with molecules of the modifier, OH groups physically screened by its organofluoric radicals, and OH groups located on the surface areas free of the modifier are quantitatively estimated. An additional silanization of the modified silica leads to coverage of silica surface areas that are free of organofluoric modifier with trimethylsilyl radicals. The heat of interaction between the methanol molecules and silica surface hydroxyl groups is determined; it is equal to 60 kJ/mol. The structure of the modifying organofluoric layer and changes in this structure that resulted from additional silanization of the surface and from the methanol adsorption are discussed.