Search

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper considers the problem of choosing the composition, structure, and size of spherical catalyst nanoparticles for carrying out plasmon-induced polymerization reactions. The concept of reducing the activation energy of the reaction in the presence of a catalyst and, accordingly, increasing the rate of a chemical reaction during heating due to the excitation of surface plasmon resonance is presented. Using the Drude model for the dielectric function, relationships were obtained for the frequency dependences of such characteristics as the real and imaginary parts of the polarizability, heating and the rate of chemical reactions when monometallic and bimetallic nanoparticles are used as catalysts, as well as the amplification of fields in their vicinity. The concepts developed in this work take into account the classical size dependence of the effective electron relaxation rate in monometallic and bimetallic nanoparticles under the assumption of diffuse scattering of electrons. Changes in the positions of the maxima of the imaginary part of the polarizability, heating, and reaction rate are analyzed with a change in the radii of monometallic and bimetallic nanoparticles. It is shown that the maxima of the dependences under study correspond to dipole surface plasmon resonances, and their number depends on the particle morphology. Changes in the amplification of electric fields in the vicinity of nanoparticles of different morphology have been studied. It has been found that the enhancement of the fields in all considered cases is maximum on the surface of the nanoparticle and decreases with distance from it. Practical recommendations are formulated regarding the size, composition and structure of nanoparticles for plasmon catalysis, which provide the highest rates of chemical reactions. Thus, all obtained frequency dependences have one maximum for monometallic and two maxima for bimetallic nanoparticles. [ABSTRACT FROM AUTHOR]

Fullerenes are interesting objects of research in view of their promising use as a nano-sized additive to coatings, films, adsorbents, as well as active components in medicine, pharmacy, cosmetology. This paper considers the possibility of modifying commercial adsorbents - silica gel and cation-exchanger based on activated carbon with available and inexpensive linear carbon radicals. Behentrimonium chloride (C22H45(CH3)3N +Cl- ) and cetyl alcohol (C16H33OН) were chosen as the latter. The obtained adsorbents were compared with a commercial sample of silica gel modified with a linear hydrocarbon radical –C18Н37. The adsorbents were described by the methods of IR spectroscopy, thermogravimetry, the main characteristics of the porous structure were determined by the method of low-temperature adsorption-desorption of nitrogen. Modification of adsorbents based on silica gel leads to a decrease in the specific surface area to 202.4 and 236.5 m² /g and the total pore volume to 0.32 and 0.39 cm³ /g, which is almost 2 half source material. Increasing the fraction of micropores contributes to better separation rates of large molecules. Treatment of cation-exchanger based on activated carbon by cation modifier leads to a significant decrease in the specific surface area, as well as to an increase in the size of pores with the predominant formation of mesopores. It is shown that the modification of silica gel is carried out both through silanol and siloxane groups, in contrast to the commercial sample of silica gel. The approximate number of modifier groups on the surface of the original SiO2 matrix was estimated, which is one modifier group ~ per 11 SiO2 molecules. To study the behavior of adsorption of C60, C70 fullerenes and their mixtures on adsorbents, column experiments were carried out with changes in the geometrical parameters of the column and the initial concentrations of the solutions. The results showed that the modified silica gels are potential adsorbents for the separation of a mixture of fullerenes with a ratio of 65/25. Silica gel modified with cetyl alcohol C16H33OH showed the best separation efficiency. By the help of an adsorbent, it is possible to separate C60 - 90.52 % from a less concentrated solution and 87.26 % from a more concentrated solution. To increase the purity of the product, it is necessary to pass the solution through the sorbent 2–3 times. The competitive capability of the proposed modified silica gels, together with economic efficiency, ease of modification, and the possibility of fullerene separation characterize the proposed adsorbents as potential materials for practical application. Due to the significantly lower cost and simpler manufacturing methods, the proposed adsorbents can be used for separation at a large scale. [ABSTRACT FROM AUTHOR]

The paper discusses the results of saponite research from the Tashkiv deposit of Ukraine. X-ray structural analysis proved the necessity of preliminary cleaning of saponites from mineral impurities. The study of the morphology, nanoprofile and topography of the surface of saponite by the methods of SEM-microscopy and Atomic Force Microscopy revealed that the mineral is represented by aggregates of nano- and microparticles of a pyramidal shape. Its characteristic feature is the heterogeneity of isomorphic substitutions of ions in the tetrahedral and octahedral sheets of the structural elementary package. According to X-ray fluorescence analysis, saponite contains a significant amount of Fe3+, which isomorphically replaces magnesium Mg2+ and, accordingly, is located mastly in the octahedral sheet of the structural package with a charge from +0.37 to +0.35. The number and mechanism of isomorphic substitutions determine the presence of a total negative charge of the crystal lattice (from –0.38 to –0.3), the value of which ensures intensive interaction with water molecules of the interpacket space with the formation of surface OH groups. Accordingly, both acidic and alkaline Lewis and Brønsted centers are present on the surface with a predominance of acidic ones, so the acidity function is 5.82, and the point of zero proton charge is pH = 5.5. During dispersion in water, a part of the alkaline centers of the side surface are transformed into Brønsted acid centers as a result of their protonation, which causes an increase in the pH of the dispersion medium to pH = 8–8.6. Accordingly, the isoionic state is reached at pH = 7.5. The difference in pH values characterizing the isoionic state of the surface and the point of zero net proton charge (PZNPC) indicates the presence of weak acid-alkaline centers on the surface. The study of the adsorption of acid-alkaline dyes showed the adsorption of alkaline (pK = 1/3) and acid (pK = 7/14) dyes on saponites. The latter is significantly reduced due to the preliminary hydration of the solid surface - mainly the lateral edges of the particles. Acidic dyes are not adsorbed from a dispersion medium with pH < 5.5 (PZNPC), and basic dyes are adsorbed at pH > 5,5( PZNPC). [ABSTRACT FROM AUTHOR]

An important environmental problem is the removal of contaminants and the purification of domestic and industrial water from pollutants of various nature. There is a separate issue of cleaning the effluents of pharmaceutical enterprises. Various chemical and physical methods are used to solve these problems, such as settling, coagulation, filtration, and sorption techniques. Adsorption with using efficient and reusable adsorbents is the most effective and cheap. In recent years special attention has been paid to the use of sorption materials based on hydrolysis lignin, which has a high sorption activity in relation to ions of some heavy metals, dyes, organic compounds and pharmaceuticals. The use of lignin as an adsorbent simultaneously solves two problems: the disposal of paper production waste and the purification of sewage from various types of pollutants. The aim of this work was to study the sorption properties of hydroylysis lignin in aqueous solution in relation to some medical substances of different chemical nature, existing in solution in cationic, anionic or neutral forms. The point of zero charge of hydrolysis lignin was determined, which is equal to рНPZC = 4.95. The adsorption of rivanol, proflavin, doxorubicin, levofloxacin, furacilin, and salicylic acid by hydrolysis lignin was studied as dependence on the pH of the solutions and the concentration of adsorbates. It was found that adsorption largely depends on the structure of the pharmaceuticals and the pH values of the solutions. It is shown that the studied medical compounds, which exist in the solution in the form of cations, are adsorbed the best (rivanol, proflavin, doxorubicin). Adsorption of these substances occurs mainly due to electrostatic interaction with negatively charged surface groups. Adsorption of anionic form (salicylic acid) is the smallest and is observed only at quite low pH values. Levofloxacin is adsorbed mainly in the form of zwitter ions, and furacilin is in neutral form. The adsorption of these both compounds occupies an intermediate value of adsorption amount. The obtained adsorption isotherms are well lined up in Langmuir coordinates. Quantitative parameters of adsorption values - of maximum adsorption and equilibrium constants were calculated. Quite high values of these parameters indicate that hydrolysis lignin can be used as an adsorbent for the removal of these pharmaceuticals. [ABSTRACT FROM AUTHOR]

The paper describes the method of obtaining the SiC/porous-Si/Si heterostructure and the study of its structural and morphological properties. The method of obtaining heterostructures consisted of several stages: electrochemical etching of single-crystal silicon p-Si (111), annealing of porous Si in a CO atmosphere. The fabricated structures were characterized using scanning electron microscopy, X-ray spectral microanalysis, X-ray phase analysis, highresolution diffractometry, X-ray reflectometry, and photoluminescence. The method of high-resolution diffractometry made it possible to assess the state of the SiC/Si(001) system. On the 2Theta-omega diffractograms, in addition to the (111) reflection of the Si substrate in the region of 2 Theta = 35.67, the (111) reflection of the cubic SiC film is observed. This means that the formed SiC film is textured in the (111) growth direction of the silicon substrate. The classical technique of X-ray phase analysis showed the presence of a hexagonal phase in the SiC film. The concentration ratio of cubic to hexagonal phase is 80 % cubic and 20 % hexagonal. The RMS deformation of the lattice (ε) in such a structure is ε = 1∙10–2. The photoluminescence spectra of the SiC films of the experimental samples in most cases consist of narrow and broad bands and extend from the near ultraviolet to the entire visible spectrum. At the same time, in the range of wavelengths corresponding to the energy forbidden zones of hexagonal polytypes and cubic polytypes, a noticeable glow was observed in most of the samples. In some samples, luminescence in the area of hexagonal phases was predominant. In the photoluminescence spectra both at T = 77 K and at T = 300 K, a narrow line at a wavelength of ~ 371 nm is observed. [ABSTRACT FROM AUTHOR]

The paper considers the problem of light absorption by a nanocomposite with randomly oriented metal spheroidal particles-inclusions, provided that the volume content of such inclusions is small. Expressions for the frequency dependences of the effective dielectric function and the absorption coefficient of the metal-dielectric nanocomposite are obtained within the effective medium model taking into account the axial symmetry of spheroidal inclusions. The effective relaxation rate of electrons is introduced using the kinetic approach. Numerical calculations are performed for the cases when inclusion particles have the form of prolate and oblate nanospheroids. The results of the calculations indicate the presence of two maxima of the absorption coefficient, which correspond to longitudinal and transverse surface plasmon resonance. The change in the position and magnitude of the maxima of the frequency dependences of the effective dielectric function and the absorption coefficient with varying the size and shape of the spheroidal particles-inclusions is analyzed. It is shown that the greater the difference in the lengths of the semi-axes of the spheroids, the greater the distance between the maxima of the effective dielectric function and the absorption coefficient, and the shape of the curves depends on the eccentricity of spheroidal inclusions. It has been found that the position of the maxima is significantly influenced by the choice of the material of the inclusion particles and the matrix medium, while the height of the maxima is largely influenced by the shape of the nanoparticles, as well as their volume content in the composite medium. It is proved that, dependent on the material of nanoparticles-inclusions, both maxima of the absorption coefficient can be found in the visible part of the spectrum (for Au inclusions) or in the ultraviolet (for Al inclusions). It is also possible that one maximum lies in the visible part of the spectrum, and the other in the ultraviolet, which is the case for inclusions of Pd, Pt, Cu, Ag. [ABSTRACT FROM AUTHOR]

In this paper, changes in the porous structure of carbon material are investigated during chemical activation of apricot pit at different temperatures. The main purpose of the research has been to study the features of the internal micro- and mesostructure of the carbon surface, as well as to find patterns in the size distribution of pores dependent on the carbonization temperature of plant raw materials and subsequent chemical activation. The object of the study is porous carbon material, obtained from dried apricot fruit pits, pre-crushing, and cleaned from the core. This raw material has been carbonized at 300–900 °C with an interval of 100 °C and subjected to chemical activation by potassium hydroxide in the weight ratio XК, where ХК= m(KOH)/m(C). Thereby, a series of samples C3÷C9 has been obtained. The porous structure characteristics (specific surface area and total pore volume) of porous carbon material have been determined based on the analysis of nitrogen adsorption / desorption isotherms. It has been found that these materials have a frame structure with a large number of micropores. The analysis of literature data has revealed that the experimental curves belong to the isotherms that are characteristic of multilayer adsorption in micro- and mesopores of materials of organic origin. The hysteresis loop observed on these isotherms is related to the sorption processes in narrow pores. It has been found that carbonization of raw materials and chemical activation contribute to the cleaning of the frame structure, and there are acceptable modes of heat treatment of raw materials of plant origin, which determine the optimal pore size distribution and have a specific surface area S = (1042–1313) m² /g. With the help of scanning electron microscopy, the peculiarities of the formation of impurities on the surface of the original samples have been studied and their nature has been elucidated. It has been found that the largest total pore area has a sample carbonized at 600 ºC, and the largest pore volume Vtotal = 0.68 cm³ /g for sample C3 is associated with a significant number of mesopores in the porous structure. As the carbonation temperature increases to 800-900 °C, narrow micropores degenerate and the carbon matrix transforms, resulting in a decrease in both the total pore area and the total porous volume. In this paper, changes in the porous structure of carbon material are investigated during chemical activation of apricot pit at different temperatures. The main purpose of the research has been to study the features of the internal micro- and mesostructure of the carbon surface, as well as to find patterns in the size distribution of pores dependent on the carbonization temperature of plant raw materials and subsequent chemical activation. The object of the study is porous carbon material, obtained from dried apricot fruit pits, pre-crushing, and cleaned from the core. This raw material has been carbonized at 300–900 °C with an interval of 100 °C and subjected to chemical activation by potassium hydroxide in the weight ratio XК, where ХК= m(KOH)/m(C). Thereby, a series of samples C3÷C9 has been obtained. The porous structure characteristics (specific surface area and total pore volume) of porous carbon material have been determined based on the analysis of nitrogen adsorption / desorption isotherms. It has been found that these materials have a frame structure with a large number of micropores. The analysis of literature data has revealed that the experimental curves belong to the isotherms that are characteristic of multilayer adsorption in micro- and mesopores of materials of organic origin. The hysteresis loop observed on these isotherms is related to the sorption processes in narrow pores. It has been found that carbonization of raw materials and chemical activation contribute to the cleaning of the frame structure, and there are acceptable modes of heat treatment of raw materials of plant origin, which determine the optimal pore size distribution and have a specific surface area S = (1042–1313) m² /g. With the help of scanning electron microscopy, the peculiarities of the formation of impurities on the surface of the original samples have been studied and their nature has been elucidated. It has been found that the largest total pore area has a sample carbonized at 600 ºC, and the largest pore volume Vtotal = 0.68 cm³ /g for sample C3 is associated with a significant number of mesopores in the porous structure. As the carbonation temperature increases to 800-900 °C, narrow micropores degenerate and the carbon matrix transforms, resulting in a decrease in both the total pore area and the total porous volume. [ABSTRACT FROM AUTHOR]

This paper presents a theory that allows one to calculate the energy absorbed by spheroidal metal nanoparticles when irradiated by ultrashort laser pulses of different duration in the region of surface plasmon resonance. Simple analytical expressions are obtained to calculate the absorption energy dependent on the frequency of carrier laser wave, on the pulse duration, and on the ratio between the axes of the ellipsoids. It is shown that at the frequency of the carrier (laser) wave, which coincides with that of the surface plasmon, the maximum absorption is observed for spherical nanoparticles. As the carrier frequency deviates from the surface plasmon one, two maxima appear in the absorption spectrum, dependent on the ratio of spheroidal axes: one corresponds to the elongated particles and the other to the flattened ones. [ABSTRACT FROM AUTHOR]

Oil and oil products enters surface waters as a result of man-made disasters, caused, in particular, by military operations. In order to prevent ecological catastrophe, it is necessary to remove hydrocarbons from water surface. The paper is devoted to the development of materials for the extraction of non-polar liquids from aqueous media. Magnetic sorbents based on non-carbonized biopolymers (both plant cellulose and keratin) are proposed. Biopolymer matrices of different morphology on the level of fiber bundles were used for the composite preparation. Dependent on origin, the matrices are characterized by different morphologies at the level of fiber bundles: they are straight (cellulose obtained from wood and corn cobs), helical (cellulose of tea leaves or scaly (keratin from animal wool). Magnetite particles were inserted into biopolymer matrices after the removal of non-cellulose and non-keratin inclusions from them. The samples were investigated with SEM and FTIR techniques, magnetite was identified with XRD analysis. The most homogeneous distribution of magnetic particles, a size of which is less than 1 μm, was found for the matrix obtained from corn cobs. This composite contained the least amount of iron (0.24 mass. %), namely this sample demonstrates the best flotation. The sorbent based on cellulose from tea leaves contained 71% of iron: the particles sink almost completely. The capacity towards non-polar liquids was estimated as follows (g g–1): 1.6–8.6 (vegetable oil), 10.5–16.4 (crude oil), 9.8–14.5 (kerosene). After the removal of crude oil from water surface, no film of this liquid was visually observed. The value of chemical oxygen demand was ≈ 0.2 mgO2 dm–3, this is less than the demand for drinking water. Moreover, the sorbent can be easy removed from water surface with magnet. As found, the sorbents can be used for removal of toxic metal ions from water. As found, magnetic particles improves sorption of Pb2+ ions but decrease Cd2+ sorption. Thus, the sorbents with small content of inorganic modifier can be used for the removal of oil and oil products from water surface. The sorbents, which demonstrate bad flotation, can be used for the recovery of inorganic ions. The advantages of biopolymer-based sorbents over known material is a simple preparation procedure that involves cheap and available feedstock. Moreover, the sorbents can be easy separated from aqueous phase with magnet. [ABSTRACT FROM AUTHOR]

The creation of new nanomaterials for absorbtion of electromagnetic radiation microwave range is an important direction in consequence of electromagnetic pollution of the environment. The aim of the paper was to develop and synthesize the polymer-filled systems based on the polychlorotrifluoroethylene and tin dioxide modified by nickel ferrite in order to study their electrophysical properties as potential materials absorbing electromagnetic radiation. NiFe2O4/SnO2 nanocomposites with a volume content of nickel ferrite on the surface of tin dioxide from 0.62 to 0.8 were synthesized by co-precipitation. Size of SnO2 and NiFe2O4 nanoparticles was determined by a transmission electron microscope and its about 30–50 nm and 15–30 nm, respectively. For the NiFe2O4/SnO2 nanocomposites the values of complex permittivity and complex permeability in the microwave range, values of conductivity at low frequencies were investigated. Maximum values of complex permittivity and complex permeability were found for NiFe2O4/SnO2 nanocomposites at the volume content of nickel ferrite 0.62. An increase was observed in the complex permittivity for the NiFe2O4/SnO2–polychlorotrifluoroethylene system, 2–3 times greater than the values related to the NiFe2O4/SnO2 nanocomposites. The electrical conductivity at low frequencies (100 Hz) of polymer composites increases by an order of magnitude with a decrease of the concentration of nickel ferrite on the surface of tin dioxide. It was found that the calculated absorption coefficient of an electromagnetic wave in the frequency range 1–41 GHz for NiFe2O4/SnO2 nanocomposites is about 2 times greater than that for nickel ferrite. It is shown that the creation of nanocomposites based on a conductive component modified by a magnetic component is more efficient for the processes of absorption of electromagnetic waves in the microwave range at optimal ratios of the values of the permittivity and permeability than pure ferrite. [ABSTRACT FROM AUTHOR]

In this paper it is discussed the colloidal-chemical method of synthesis of dispersed composite bentonite-ferromagnetic powders that are stable to oxidation. It is shown that for this purpose it is advisable to use acid-activated bentonite clay with a high content of clay mineral - montmorillonite. Modified bentonite is a slightly amorphized silica product that serves as a porous matrix for crystallization of goethite α-FeOOH. The formation of goethite occurs at the centers of crystallization - particles of ferrihydrite stabilized by activated bentonite (Fh) during precipitation with an ammonia solution from a ferrum(ІІІ) hydroxide FeO(OH)·nH2O colloidal solution. In the resulting composite, goethite particles are cemented in the aluminosilicate framework of activated dispersed clay as a result of the interpenetration of the structures of the double layered hydroxide and activated bentonite. Further recrystallization of goethite with the formation of mainly magnetite and possibly maghemite in the structure of activated bentonite is provided by thermal firing of composite goethite powder with the addition of metallic iron powder. The methods of IR spectroscopy, X-ray structural analysis, electron microscopy and the study of magnetic properties showed that the obtained composite powder is environmentally friendly and exhibits the properties of a soft magnetic material. Such powders are promising for use as sorbents for environmental cleaning, as well as for biomedical purposes due to their low toxicity and high value of saturation magnetization. [ABSTRACT FROM AUTHOR]

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper considers an approach to the processing of waste of agro-industrial raw materials due to chemical activation. To obtain a sorption material, waste was used, which is the shell of Juglansregia walnuts. The aim of the work was to develop adsorbents from walnut shells with a large proportion of mesopores, to determine the parameters of the porous structure and to study their adsorption capability to absorb egg albumin as a marker of medium molecular toxins of a protein nature. Activated carbon samples with a high mesopore content (550 m²/g) were obtained by combined activation of the feedstock. The sorption of one of the obtained samples and, for comparison, the medical product SORBEX was studied by the spectrophotometric method, and its effectiveness was proved in the absorption of egg albumin from aqueous solutions. The significant capability of the obtained sample to sorb protein (35–38 mg/g) was shown, it has been assumed that in the process of sorption, macromolecules are concentrated near the inlets into the pores of the adsorbent. It can be stated that the adsorption of albumin increases in proportion to the increase in the specific surface area of the mesopore. Using the obtained sorption isotherms, the parameters of adsorption processes were calculated. Adsorption isotherms were calculated using the Langmuir and Freundlich equations. It is shown that the maximum adsorption values calculated using the Langmuir equation are in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

A brief literature review proves that nanosized fluorescent carbon materials are widely used. In particular, they are promising in biomedicine (due to biocompatibility – for example, for biovisualization); optoelectronics; as chemical fluorescent sensors for measuring the concentration of metals, pH, anions, organic substances and biomolecules; as markers for fingerprinting. This paper investigates carbon materials obtained by oxidation of activated carbon, which are similar in their optical characteristics to carbon nanotubes. The aim of this work was the synthesis of nanocarbon material from available chemical raw materials. As a prototype, the synthesis is based on the method of obtaining carbon weakly acid cation-exchange resin. The nanocarbon material is easily dispersed in water, forming stable colloidal solutions that exhibit luminescence in the blue-green region of the visible spectrum. According to the results of thermogravimetric analysis, the thermal destruction of surface functional groups was found. The nature of the functional groups on the surface of the carbon nanomaterial was based on the obtained data of infrared spectra. The purity of the samples was monitored by X-ray diffraction analysis of the powder. For the pure sample, only the amorphous carbon spectrum was observed, and for the crude, NaCl reflexes were observed. In the region of MALDI positive ions, clusters of molecular mass have been obtained, which may belong to fullerene-like carbon structures. We believe that the high signal intensity at m/z 44 indicates a significant number of carboxyl groups. For aqueous solutions, the luminescence spectrum was measured, on which blue-green fluorescence was observed. Excitation by radiation with a wavelength was chosen based on the results of preliminary measurements of the dependence of the emission intensity on the length of the excitatory radiation. The fluorescence spectrum shows a wide maximum at 450 nm, which is slightly shifted to the longwavelength region after centrifugation of the sample and precipitation of large fractions. The method of dynamic light scattering shows that particles with a wide range of sizes are present in the solution, the maximum distribution occurs in relatively large units. [ABSTRACT FROM AUTHOR]

When metal nanoparticles (MNPs) are illuminated with a monochromatic laser wave, the frequency of which is far from the plasmon frequency (the frequency of plasmon resonances), under certain conditions (depending on the frequency of the wave, its polarization, the size and shape of the MNPs), absorption of light by MNPs can be dominated by magnetic absorption (absorption caused by the magnetic component of the electromagnetic field of the light (laser) wave). This work is focused on studying the features of absorption caused by the influence of the magnetic component of laser radiation. This issue is rather poorly studied for MNPs of non-spherical shape. Therefore, how the shape of the particle manifests itself in its absorption of laser radiation (laser pulses) is one of the goals of our research. In this work, we will study the features of magnetic absorption of light (laser radiation) depending on the shape of the particles. In this paper, we will investigate the influence of spheroidal MNPs on this process. Calculations will be carried out using the kinetic equation method, because we will consider the case when the size of the MNP is smaller than the length of free path of the electron in the MNP. Note that the kinetic approach makes it possible to obtain correct results for the case when the size of the particle is greater than the length of the free path. For non-spherical MNPs, we have developed a theory that makes it possible to calculate the energy of magnetic absorption by a particle when it is irradiated with laser pulses. The dependence of magnetic absorption on the ratio of the radii of curvature of spheroidal MNPs and the vector of the magnetic field of an electromagnetic (laser) wave was constructed and theoretically investigated. An interesting result is the absorption of energy by a spheroidal MNP as its disco similarity increases. We now use to estimate the relative contributions of electric We and magnetic Wm absorption to the total absorption. For example, let us take a gold MNP’s, then ωp ≈ 5·1015 s –1, ν ≈ 1013 s –1, R = 3·10–6 sm, ω ≈ 2·1014 s –1 (carbon dioxide laser), ε' ≈ –600, ε' ≈ 30 we received the next ratio We/Wm ≈ 2. We can see that for the given set of parameters magnetic absorption is twice as large as electric. Obviously, for different parameters of the particle and a different frequency range electric absorption can be either larger or smaller than magnetic absorption. Hence, when studying the dependence of optical absorption by MNP’s on particle form, we must allow for both electric and magnetic absorption. For an asymmetric MNP’s (for example ellipsoidal particles), apart from everything else, the ratio of the electric and magnetic contributions to absorption (as fixed frequency) is strongly dependent on the degree of particle asymmetric and wave polarization. [ABSTRACT FROM AUTHOR]

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As an alternative to means for lowering total cholesterol and low-density lipoprotein (LDL) cholesterol, the paper considers the possibility of using carbon adsorbents. From a medical point of view, the removal of cholesterol with enterosorbents is extremely effective. By binding cholesterol, sorbents reduce the risk of cardiovascular disease. The paper searches for new raw material sources and attempts to create enterosorbents with a high capability to adsorb cholesterol. The aim of the work was to develop adsorbents from spent coffee residue with a large proportion of mesopores, to determine the parameters of the porous structure and to study their adsorption capacity against cholesterol. Samples of activated carbon with a large proportion of mesopores (399 and 465 m2 /g) were obtained by the traditional method of carbonization-activation of spent coffee grounds and pre-treated hexane to remove fatty acids. The sorption of cholesterol from alcohol solutions has been studied by spectrophotometric method and its effectiveness for the prevention and treatment of atherosclerosis was proved. It has been shown that a sample of activated carbon from spent coffee residue pre-treated with hexane (maximum value reaches 7.5 mg/g) has the best sorption capacity. The intermediate position is occupied by the sample obtained without pre-treatment with solvent (maximum value reaches 6.3 mg/g). Natural Brand carbon has the weakest sorption characteristics (maximum capacity reaches 5.3 mg/g). It can be stated that the adsorption of cholesterol increases with the growth of the specific surface area of mesopores. The parameters of adsorption processes were calculated using the obtained sorption isotherms. Adsorption isotherms were calculated using the Langmuir and Freundlich equations. It is shown that the values of the maximum adsorption calculated by the Langmuir equation have a good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Zinc oxide nanostructures (NS) were grown on thin discontinuous films of noble metals of silver and gold in order to study their structure, optical properties as well as photocatalytic and antiviral activity. The paper presents the results of X-ray diffraction study, scanning electron microscopy study, photoluminescence and Raman measurements. X-ray diffraction experiments demonstrate similar patterns for all grown ZnO nanostructures. The SEM images of ZnO NS grown on Ag/Si and Au/Si wafers demonstrate more dense surface microstructure compared to ZnO NS grown on bare Si wafers. The most intensive ultraviolet and deep level emissions are observed for ZnO NS grown on Ag/Si wafers. Increase in thicknesses of Ag island film from 5 nm to 10 nm gives significant increase in intensity of ultraviolet and deep level emissions. Photocatalysis of grown ZnO nanostructures was studied by methyl orange dye degradation. Superior photocatalytic results are demonstrated by ZnO nanostructures grown on Ag/Si wafers, for which constants of dye degradation were twice higher than for ZnO nanostructures grown on Si and Au/Si substrates. The photocatalytic results correlates with photoluminescence spectra: more intensive photoluminescence in ultraviolet and visible ranges of optical spectrum leads to better photocatalytic performance. The cytotoxic effect of ZnO nanostructures was studied without photoactivation by the help of cell cultures MDCK and Hep-2 while the virucidal effect of ZnO nanostructures was studied by the help of Influenza A virus (H1N1) (strain FM / 1/47) and human adenovirus serotype 2 (HAdV2). ZnO nanostructures in a 1:10 dilution were not toxic to Hep-2 and MDCK cells. Most of the tested ZnO nanostructures exhibited no virucidal activity against human adenovirus serotype 2 (HAdV2) and influenza A virus (H1N1) (strain FM / 1/47) in the absence of photoexcitation. [ABSTRACT FROM AUTHOR]

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on the first principles, we have shown that the decisive role in energy transfer from the fluorophore molecule to the carbon substrate (graphene) is played by the Förster-type inductive-resonance energy transfer mechanism. The Förster energy transfer rate can be calculated analytically via Fermi’s golden rule with the momentum-dependent initial final states of the graphene substrates and the HOMO (the highest occupied molecular orbital) and LUMO (the lowest unoccupied molecular orbital) states of the dye molecule. Combining first-principle calculations characterizing the hybrid carbon nanomaterials with tight-binding-based consideration of graphene wave functions allows us to obtain an analytical expression for the Förster energy transfer rate. We constructed graphical dependences of the Förster energy transfer rate at the distance R between substrate (graphene) and dye molecule for several materials. The results obtained can be applied to various hybrids based on carbon nanostructures and in general to the description of energy transfer processes in molecular functionalized nanostructures, once the molecular dipole moment and the substrate - molecule separation are known. [ABSTRACT FROM AUTHOR]

Production of valuable industrial materials from lignins as byproducts of different origin is of importance to solve the utilization problem for large amounts of these byproducts. One of the corresponding pathways is the production of water-soluble lignins, for which, interactions with water and aqueous solutions play an important role in practical application efficiency of these materials. One could assume that interactions of lignins with bound water and solutions depend strongly on the dispersion media and the presence of various (e.g., polar and ion-generating) solutes in water. The interfacial and temperature behaviors of water (solutions) bound to lignin particles in wetted powders could be effectively studied using low-temperature ¹H NMR spectroscopy applied to static samples that allows one to separate mobile and immobile phases vs. temperature below freezing point (Tf,b) of bulk liquid. At T < Tf,b several effects could be observed in wetted lignin powders such as confined space effects (CSE) in pores or voids between or inside crosslinked macromolecules, cryoscopic effects (CE) in bound solutions, partial freezing of liquids with cryoconcentration and differentiation of solutions, clusterization of bound liquids, etc. To elucidate some of these effects, wetted water-soluble lignin powders at a constant degree of hydration (h = 0.3 g/g) were studied in such dispersion media as air and chloroform-d alone or in a mixture with deuterated trifluoroacetic acid using the lowtemperature ¹H NMR spectroscopy method. Additionally, hydrated lignin molecules of different sizes were studied using quantum chemistry methods. Obtained results show that both CSE and CE affect the temperature behavior of bound water and related solutions. However, there is no their strong synergetic impact because the stronger bound the water (solution) the lower the activity of water as a solvent; i.e., CSE could partially inhibit CE. The obtained results are of interest in order to better understand different aspects of applications of water-soluble lignins under various conditions [ABSTRACT FROM AUTHOR]

The paper presents results of a theoretical study of the way a small gold nanoshell affects the efficiency of photosynthesis in the peripheral light-harvesting complex LH2 from photosynthetic bacteria. The total effect of the nanoshell is the interplay of the enhancement of the light absorption due to the strong coupling of excitons on the LH2 ring with the surface plasmon modes and the additional quenching of the excitations introduced by the proximity of the metal. The range of parameters for which a gold nanoshell enhances the total efficiency of the light harvestings has been determined. [ABSTRACT FROM AUTHOR]

The properties of heteropoly acids and of their complexes with cationic surfactants at the trace level have been studied by ESR spectroscopy, UV-VIS spectrophotometry, NMR and FTIR spectroscopy, by the method of chemiluminescence analysis applied in aqueous solutions and on the cellulose surface. For elucidation of the mechanism of chemiluminescence reactions of heteropoly acids with luminol kinetic methods, diffuse reflectance spectroscopy and liquid chromatography have been applied. For the first time one-electron reduction of heteropoly acids by luminol was confirmed by registration of diffuse reflectance spectra of reduced heteropoly acids on cellulose surface. It has been suggested that the mechanism of heteropoly acids immobilization on cellulose includes combination of Coulomb and hydrophobic interactions. A scheme of heteropoly acids immobilization on the surface was proposed based on ion exchange processes on cellulose or diethylaminoethyl cellulose surface. It has been shown that ionic associates heteropoly acid – cationic surfactant react with an alkaline solution of luminol with light emission similarly to heteropoly acids themselves. For the first time, heterogeneous chemiluminescence, namely, the chemiluminescence of heteropoly acids immobilized on cellulose, with luminol, has been used for examining the composition of ionic associates heteropoly acid - cationic surfactant. By using Bjerrum’s method it has been found that in strongly acidic media (at pH 1.0) vanadomolybdophosphoric acid forms with cationic surfactant, namely, with dodecylpyridinium bromide, not tetra-substituted but triply substituted ionic associate. This result can be explained by the fact that the fourth proton in H4PVMo11O40 is weakly dissociated; it is more strongly bound to heteropoly anion and is localized on the oxygen atom of the Mo–O–Mo angular bond. Ionic associates of heteropoly acids were used as analytical forms for highly sensitive chemiluminescence determination of P, As, Si, Ge in waters of different types. Detection limits for P, As, Si, Ge are 0.02–0.07 µg/L. Due to the high sensitivity of the method, phosphorus was successfully determined in surface water and ultrapure water, arsenic – in river and mineral water, silicon – in ultrapure water and vapor condensate of electric power stations, germanium – in water of electronic industry. [ABSTRACT FROM AUTHOR]

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to the variety of their forms and properties, silver nanoparticles (AgNPs) are promising for obtaining nanomaterials with various functional applications. Today, regardless of the method of obtaining AgNPs, there is a problem of stabilizing their surface to prevent aggregation, which significantly reduces their activity and prevents uniform distribution during the preparation of nanomaterials. The aim of this work was the synthesis of silver nanoparticles using an oligomeric ionic liquid (OIL) and the study of their structure and antimicrobial properties. In this work, for the first time, an anionic OIL with a hyperbranched structure developed by us was used as a surface stabilizer in the synthesis of AgNPs. The synthesis of AgNPs was carried out by the reduction of Ag ions in the composition of AgNO3 with trisodium citrate in the presence of this OIL. Using the methods ofUV-vis and FTIR spectroscopy, X-ray analysis, electron microscopy and the disc-diffusion method, the peculiarities of the structural organization of AgNPs and their antimicrobial properties were studied. UV-visible spectroscopy data indicate the formation of silver nanoparticles and their spherical or quasi-spherical shape. It was found that there are adsorbed ionic and carbonyl groups on the surface of the formed AgNPs, and the formation of host-guest complexes between OIL and silver ions was revealed using FTIR. The formation of AgNPs and complexes between OIL and silver ions is also confirmed by X-ray diffraction. According to electron microscopy, the size of the synthesized nanoparticles varies from 5 to 16 nm, with an average value of 10.2 nm. This average value is very close to the value of 9.3 nm obtained from the results of X-ray analysis. The synthesized silver nanoparticles showed a very high antimicrobial activity against C. albicans fungi, while the width of the inhibition zone (d) was 34 mm. Also, the AgNPs powder shows very high activity against gram-positive bacteria S. aureus (d = 30 mm) and gram-negative bacteria E. coli (d = 12 mm). The approach developed by us to the synthesis of AgNPs in the presence of OIL as a surface stabilizer with certain functionalization of the latter opens up new opportunities in the synthesis of AgNPs and the preparation of highly dispersed related systems, including functionalized nanocomposite polymer materials with antimicrobial properties. [ABSTRACT FROM AUTHOR]

The contact wetting is one of the effective methods of studying the adsorption capacity of sorbents. The purpose of the work was to compare the experimentally obtained data on the adsorption capacity of shungite, obtained by the sessile drop method, and the results of modeling the behavior of liquid droplets on heterogeneous surfaces using the Boltzmann lattice method, and to show the suitability of the simplified version of the LBM method that we applied within the framework of a two-dimensional model for modeling complex cases of contact interaction between liquids and sorbent, when it cannot be carried out by the method of contact wetting. The adsorption properties of shungite with regard to the extraction of various impurities from water-alcohol solutions and the capability of the sorbent to recover were investigated by the method of contact wetting and analyzed by involving the data obtained by the methods of nitrogen adsorption, thermogravimetry and IR spectroscopy. It is shown that the adsorption properties of shungite are due to the presence on its surface of hydroxyl functional groups attached to carbon atoms in phenol or enol form, which give the surface hydrophilic characteristics. These groups play a key role in the adsorption of components from the liquid (aqueous) phase due to the formation of a hydrogen bond during the sorption of components from the liquid phase, and are restored after heating in the temperature range of 80–180 °C with the formation of carbon-containing gases and water. It has been found that silanol groups present in shungite do not participate in sorption. Compared to the original shungite sample, the sample after five cycles of adsorption is characterized by a noticeable effect of mass loss (1.8 %) in the temperature range of 80–180 °С. At the same time, the loss of mass is not significant at temperatures below 100°С. This suggests that the sorbed substances are in the pores and not on the surface of shungite, and they begin to be removed only after heating above 100°C. The LBM method was used to study fast-moving processes at the meso-level. A comparative analysis of the experimental data obtained by the method of contact wetting with the results of simulation by the Boltzmann lattice method within the framework of the two-dimensional model was carried out. 2D modeling by the LBM method turned out to be an effective means of studying capillary condensation in mesopores, anticipatory wetting of the solid phase, liquid penetration into a porous medium with different topologies, and the formation of anisotropic droplets and anisotropic bridges. The role of mesopores in the sorption process was analyzed by modeling the behavior of liquid droplets on heterogeneous surfaces and using data on the course of adsorption and capillary processes on the surface of a solid phase with different levels of porosity, roughness, and functional composition. [ABSTRACT FROM AUTHOR]

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purifying aqueous solutions from radioactive contamination is an extremely relevant scientific topic today. Many organic and inorganic adsorbents can be recommended for the adsorption of heavy metal ions and radionuclides from aqueous solutions, or as carriers for storage and disposal of radioactive waste. Since radionuclides are sources of ionizing radiation, the radiation resistance of the adsorbent is an important characteristic. These studies aim to investigate the titanium silicate behavior and its adsorption properties' changes or their invariability in the field of intense β-radiation. Experimental techniques describe the synthesis of titanium silicate adsorbent by sol-gel method and the study of its adsorption capacity toward Ba2+ cations. The adsorption of Ba2+ cations was investigated under batch conditions with neutral pH of the solution. Initial and residual concentrations of Ba2+ cations were controlled by direct complexometric titration with Na-EDTA with Eriochrom Black T as an indicator. The study of the radiation resistance of the adsorbent to high-energy β-radiation was performed using a 90Sr-90Y β- - source “Sirius” installed in the Microtron Laboratory of the Uzhhorod National University. The distance from the source to the adsorbent samples was 20 cm. The flux of electrons at this distance was 108 el/cm2 ‧per second. The maximum energy of beta particles was 0.456 MeV for 90Sr and 2.28 MeV for 90Y. The maximum duration of exposure was 21 days, which corresponds to 1310 Gy. Raman spectroscopy of irradiated and nonirradiated samples of TiSi was performed using a Raman spectrometer XploRA PLUS installed in the Center for Collective Use of Scientific Equipment “Laboratory of Experimental and Applied Physics” of Uzhhorod National University. Results consist of kinetic of Ba2+ adsorption by titanium silicate and irradiated titanium silicate; isotherm of Ba2+ adsorption and Raman spectrum of nonirradiated, irradiated titanium silicate (TiSi) and TiSi after Ba2+ adsorption. Results showed that the value of the maximal adsorption was 140.5±9.2 mg/g (6.55 %) under a confidence level of 95 %. The adsorption values of barium ions by irradiated and non-irradiated titanium silicate coincide. This indicates that the adsorption properties of this adsorbent do not change under the influence of such a radiation dose. The Raman spectra of irradiated and non-irradiated titanium silicate coincide, while they do not identify free radicals, or ionic formations, which would indicate a change in the properties of the adsorbent under the influence of beta radiation. It can be argued that this adsorbent is radiation-resistant to beta-radioactivity, with a radiation dose of 1310 Gy. The main conclusion of the present work is that the studied sample of titanium silicate is radiation-resistant. It can withstand a radiation dose of 1310 Gy without changing its adsorption properties. Titanium silicate can be used for the adsorption of strontium radionuclides, it can be a carrier for the disposal of radioactive waste. [ABSTRACT FROM AUTHOR]

The aim of presented work was to synthesize geopolymers based on the metakaolin and to determine their adsorption capability in the process of cesium and strontium ions removal from the aqueous solutions. New approaches were proposed for obtaining the two samples of geopolymers in techologically suitable forms. Morphology of materials was investigated by means of X-ray fluorescence analysis (XRF), low-temperature nitrogen adsorption/desorption and scanning electron microscopic studies (SEM). As it follow from the data of XRF analysis, SiO2 and Al2O3 oxides found to be the major components in all samples investigated (~ 54–84 wt. %). As was determined by SEM studies, geopolymers consisted from nanosized particles, amorphous geopolymers binder and unreacted kaolin. It has been found that all samples involve the mesopores with approx. 1–40 nm radii. The greatest specific surface area calculated by the Brunauer-Emmet-Teller (BET) method had the sample obtained in the forms of spherical rods (SBET = 88 m² /g) that about 10 times greater than for initial kaolin taken for synthesis. The ion exchange capacities of materials in the process of Cu2+, Cs+ and Sr2+ removal from water solution were determined and it was found that these properties depends on the method of materials obtaining. Data showed that the geopolymers were more effective for removal the desired ions than initial kaolin. The greatest adsorption capacity towards cesium ions was received on the samples obtained in forms of pyramids and was reached 1.75 mmol/g. Experimental data were fitted into the Langmuir models and the main Langmuir constants were calculated. When analysing the data of investigation with comparing the literature data it was noted that geopolymers obtained can be used in adsorption technology for purification of water from radionuclides as technologically suitable sorbents. [ABSTRACT FROM AUTHOR]

Samples of MnOx-Na2WO4/SiO2 based on a mesoporous silica matrix were synthesized using manganese acetate, sodium tungstate, tetraethoxysilane (TEOS) as precursors and cetyltrimethylammonium bromide (CTAB), citric acid and triethanolamine as pore generating agent and characterized by scanning electron microscopy with energy dispersive elemental analysis (SEM/EDS), X-ray diffractometry (XRD), electron magnetic resonance (EMR), N2 adsorption-desorption measurements and tested as a catalyst for the reaction of oxidative condensation of methane (OCM). It is shown that the MnNaW/SiO2 catalyst consists of Mn2O3, MnO2, Na2WO4 and SiO2 phases. The EMR and SEM/EDS data indicate a noticeable effect of the reaction conditions on the surface structure and the distribution of catalytically active components in the catalyst structure. Significant changes in the values of the specific surface area and pore volume of the samples with increasing temperature and duration of the reaction were found (the values of the specific surface area and pore volume, respectively, 116.8 m² /g and 0.590 cm³ /g - up to and 46.1 m2 /g and 0.232 cm³ /g after 15 hours of catalyst operation in the OCM reaction at 800 °C). It has been shown that under the conditions of the OCM reaction, the elemental composition of the surface of the MnOx-Na2WO4/SiO2 catalyst changes, and the degree of change depends on the duration of the OCM reaction. Under the influence of the reaction mixture CH4/O2, the content of Mn and W decreases in the first two hours, and the trend towards a decrease in their amount on the catalyst surface with an increase in the duration of the OCM reaction is generally preserved. A detailed X-ray phase analysis also indicates a change in the phase composition of this catalyst under the influence of the CH4/O2 reaction mixture. It is assumed that under the reaction conditions (700–800 °C) the MnOx-Na2WO4/SiO2 catalyst is silicon dioxide particles basely with the cristabolite structure, the surface of which is coated with molten sodium tungstate containing nanosized particles of MnOx structures activated by sodium ions and WOx. [ABSTRACT FROM AUTHOR]

The use of wound dressings is gaining more and more popularity, especially in the field of tactical and military medicine. Developing wound dressings capable of facilitating wound treatment and reducing healing time is one of the challenges of modern science. So, sodium alginate (Alg) is a good candidate for the development of wound dressings due to its bio- and hemocompatibility and biodegradability. However, Alg has its shortcomings, which can be dispatched by modification. The purpose of this work was to investigate the effect of Alg modification on the kinetics of ethonium release from crosslinked with Ca2+ ions samples. For this purpose, a method of Alg modifying with octane-1-amine was developed without the use of organic solvents and with the use of 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDCl) as an initiator. The optimal parameters of alginate modification process were defined as 60 °С temperature and 24 hours duration. Physicochemical methods confirmed the success of the modification. Films based on the alginate modified with octane-1-amine (AlgM) were obtained using a calcium chloride solution as a crosslinker. The kinetics of swelling was studied and we found that the degree of swelling of the sample based on AlgM after 10 minutes is twice as large (α = 0.71) as for Alg (α = 0.37), which indicates a faster release of drugs. It has been found that the kinetics of release of ethonium depends not only on the kinetics of swelling but also on the chemical nature of the drug. The ethonium was immobilised in alginate films as a model of bactericidal drug. The kinetics of ethonium release was studied at different pH values corresponding to the pH of healthy skin (5.5), open wounds (7.2) and inflamed wounds (8.2). It was found that the release of ethonium from the sample based on AlgM is more pH-sensitive and prolonged, compared to the sample based on Alg. This effect is explained by the appearance of an additional mechanism of retention of ethonium by AlgM due to hydrophobic-hydrophobic interactions in the films. The prolonged release properties observed in the drug-loaded samples make them promising candidates for the development of targeted drug delivery systems and wound dressings, which are particularly relevant for the treatment of chronic and burn wounds. Future research will focus on optimizing the crosslinking method and exploring potential applications of modified alginate-based materials in biomedical sciences. [ABSTRACT FROM AUTHOR]