Organomineral composite materials for drying of gaseous streams

Specific features of the synthesis of the organomineral binding agent, polyvinyl alcohol—silica sol, with high sorption activity were studied. The adsorption properties of the new material towards water were examined under equilibrium and dynamic conditions. The kinetics of water adsorption and granules based on the new material were investigated. The possibility of using the organomineral binder in technology of the preparation of granulated and block adsorbents designed for drying of gaseous streams was evaluated.     

Guanidine-Containing Organomineral Complexes as Biocide Additives to Polymeric Composites

Obtaining and using polymeric composite materials with biocide properties is of considerable practical interest both for making construction materials stable against biological corrosion and for improving the sanitary-epidemiological situation. The method suggested for obtaining biocide polymeric composites is based on using new guanine-containing polymers immobilized on montmorillonite as biocide additives. Macromolecular compounds based on guanidine polymers are characterized by high biocide efficiency and low toxicity, and their use as organomineral complexes with montmorillonite can rule out washing-out of the additive from the composite and improve the distribution of the additive in the composite. Methods are suggested for obtaining organomineral complexes in a wide range of compositions. It is shown that composites based on polyethylene and the additives have high biocide efficiency toward micromycetes and gram-positive and gram-negative bacteria.     

Investigation of Pathogenic Mineralization on Human Heart Valves. 1. Chemical and Phase Composition

The chemical and phase composition of pathogenic minerals formed on human heart valves (cardiolytes) has been studied.It is shown that cardiolytes are organomineral aggregates, whose mineral component is represented by nonstoichiometric carbonate-containing hydroxyl apatites with a variable Ca/P atomic ratio.     

Bentonite-based phosphoric acid organomineral cationite

The conditions under which bentonite-based phosphoric acid organomineral cationite is obtained were assessed and its acid-base and physicochemical properties were studied.     

Polymer composites based on polythiourethane and fluorinated organomontmorillonite

Russian Journal of Applied Chemistry - The effect exerted on the mechanical properties and thermal oxidative stability of polythiourethane elastomers by new organomineral complexes based on...     

Technology for producing adsorbents from petroleum residues

Advantage of use residue from thermal cracking and products of its condensation as components of the mixture for manufacturing mechanically rigid (93%) granulated and ground carbon sorbents with extended volume of micropores (up to 0.27 cm³/cm³), showing enhanced sorption activity (E is up to 25.6 kJ mol^?1) and high ability of separation various gas mixtures is demonstrated. As a carrier for medicine preparations these adsorbents show higher performance as compared with industrial samples. Solutions of the cracking residue can be used for impregnation of worked out zeolites for petroleum technology and for production of organomineral adsorbents with high adsorption capacity on extraction mercury from sewages.     

An Organomineral Composite Sorbent for Selective Recovery of Cu(II) from Aqueous Solutions

The phase composition, microstructure, and volume distribution of the dispersed lead sulfide phase in the matrix of the synthesized organomineral composite sorbent KU-2×8?PbS were studied. The cation exchanger granules are coated with a virtually continuous layer of lead sulfide up to 1.8–2.5 μm thick. In the volume of cation exchanger granules, the PbS phase forms discrete spherical particles with the mean diameter of 90–100 nm. Experiments on competing sorption of Cu(II) and Zn(II) from nitrate solutions revealed high selectivity of the sorbent to copper. Zinc concentrations of up to 0.004 mM do not noticeably affect the copper sorption, ensuring the possibility of separating the metals in the sorption step.     

Trends in Sorption Recovery of Platinum Metals: A Critical Survey

The major trends in research into the sorption recovery and separation of platinum metals are critically surveyed. The advantages and disadvantages are described for ion-exchange and complexing sorbents based on organic polymers, chemically modified silicas, sorbents with applied macrocyclic compounds, hybrid organomineral sorbents with supported polymers, molecular imprinted sorbents, solid-phase extractants based on ionic liquids, biosorbents, and other types of sorbents. The technological potentials of these sorbents are evaluated.     

Sorption in the chemistry of rare earth elements

Sorption methods for the concentration and separation of rare earth elements are reviewed. Sorbents based on organic polymers, specifically strongly and weakly acidic cation exchangers, anion exchangers, and complexing sorbents, are successively considered. Data on the use of inorganic sorbents and solid phase extractants in the rare earth chemistry are also given. Considerable attention is paid to hybrid organomineral materials constituting a promising class of sorbents. Advantages and disadvantages of using biosorbents, molecularly imprinted sorbents, and nanosorbents for the concentration and separation of rare earths are discussed.     

Effects of surfactants on the adsorptive removal of basic dyes from water using an organomineral sorbent-iron humate

The sorption of basic dyes (methylene blue, malachite green, rhodamine B, crystal violet) onto a nonconventional organomineral sorbent-iron humate-was examined in the presence of various kinds of surfactants. It was found that nonionic (Triton X-100) and cationic (cetyltrimethylammonium bromide) surfactants exhibited a relatively small effect on the dye sorption. Anionic surfactants (sodium dodecyl sulfate), on the other hand, affected (in most cases) dramatically the sorption of basic (cationic) dyes. Typically, the dye sorption was enhanced in the presence of low concentrations of anionic surfactants. At high surfactant concentrations, a steep decrease in the dye sorption was observed in some systems, probably due to the formation of micelles that solubilize the dye molecules and prevent their sorption. A model describing these experimental dependencies was proposed. The sorption of basic dyes onto iron humate may be described by the pseudo-second-order kinetic equation. Diffusion processes were identified as the main mechanisms controlling the rate of the dye sorption.     

Specific features of pathogenic mineral formation in the human body

Key relationships in pathogenic mineral formation within the human body were summarized. It was shown that pathogenic organomineral aggregates in human body are formed in complex multicomponent media containing organic and inorganic components. In the course of lithogenesis, the composition of biological fluid undergoes major changes. Phase formation in human urine and oral fluid in the initial stages leads to emergence of less thermodynamically stable phases, i.e., is kinetically controlled. Amino acids, as well as a number of inorganic impurities, are actively involved in crystallization of the main phases of renal calculi.     

A study of cetylpyridinium cation sorption on Na-vermiculite

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 Δd = 20.25 Å) and bilayer (Δd = 37.27 Å) intercalation structures with a tilt angle of cetylpyridinium ions to the silicate basal surface of ≈57° has been revealed.     

Isolation,Separation, and Preconcentration of Biologically Active Compounds from Plant Matrices by Extraction Techniques

Development of efficient methods for isolation and separation of biologically active compounds remains an important challenge for researchers. Designing systems such as organomineral composite materials that allow extraction of a wide range of biologically active compounds, acting as broad-utility solid-phase extraction agents, remains an important and necessary task. Selective sorbents can be easily used for highly selective and reliable extraction of specific components present in complex matrices. Herein, state-of-the-art approaches for selective isolation, preconcentration, and separation of biologically active compounds from a range of matrices are discussed. Primary focus is given to novel extraction methods for some biologically active compounds including cyclic polyols, flavonoids, and oligosaccharides from plants. In addition, application of silica-, carbon-, and polymer-based solid-phase extraction adsorbents and membrane extraction for selective separation of these compounds is discussed. Potential separation process interactions are recommended; their understanding is of utmost importance for the creation of optimal conditions to extract biologically active compounds including those with estrogenic properties.     

Organomineral sorbents based on clinoptilolite-containing tuffs

The anion-exchange properties of a new organomineral sorbent obtained by modification of clinoptilolite-containing tuffs by polyhexamethyleneguanidine have been studied after different periods of storage (time after synthesis) and numbers of sorption-regeneration cycles. The sorbent can be used as a cation- and an anion-exchanger simultaneously. Selectivity coefficients (exchange constants) for F^–, SO₄ ^2–, and HPO₄ ^2– ionsvs. Cl^– ions on modified clinoptilolite-containing tuffs have been determined. The modification improves the mechanical properties of clinoptilolite tuffs.For part 1, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1554–1556, September, 1994.     

Nanofiltration membrane behavior in a supercritical medium

The permeability values of “TN” organomineral nanofiltration membranes to water, L, and to supercritical CO₂, G, were compared. The resulting values for G were an order of magnitude higher than for L. The difference may be directly related to the viscosity difference between the two fluids. Temperature- and pressure-related variations in G were also analyzed; for this purpose, Poiseuille's model satisfactorily accounts for experimental behavior, while Knudsen's model is unsuitable. A hysteresis effect was observed on the isotherms corresponding to variations in G versus pressure, suggesting partially irreversible CO₂ adsorption on the micropore walls, that would diminish the radius. This phenomenon could be enhanced by an increased fluid density and viscosity.     

Mechanism of the grafting of organosilanes on mineral surfaces

Summary The grafting of minerals by alkenylchlorosilanes leads to organomineral derivatives which are superficially covered by unsaturated organic groups. These groups may be of value when the grafted mineral is used as a reinforcing agent in a polymeric matrix. In this case, the unsaturated grafted groups copolymerize with an organic monomer to build up a composite material. It is therefore of importance to preserve the unsaturated character of the alkenyl-silane during the grafting reactions. It is shown that in certain synthesis conditions, the hydrochloric acid present in the reaction medium adds to the alkenyl-groups. For instance, in the grafting of methylvinyl-dichlorosilane, this reaction is of minor importance, whereas in the case of allyldimethylchlorosilane, no allyl groups are grafted as such on the mineral surface.

---

Zusammenfassung Die Pfropfung von silicatischen Mineralen mit Alkenylchlorosilanen führt zu organischen Derivaten, deren Oberfläche mit ungesättigten organischen Gruppen bedeckt ist. Diese Gruppen können Vorteile bieten, wenn die so behandelten Minerale als Fül-stoffe oder Verstärker in einer Polymermatrix eingesetzt werden. Die ungesättigten Gruppen können miteinem organischen Monomer kopolymerisieren und ein echtes Verbundmaterial bilden. Die Pfropfung muß allerdings so geführt werden, daß der ungesättigte Charakter der Alkenylsilane erhalten bleibt. In der Arbeit werden experimentelle Bedingungen dafür berichtet.

---

---

With 2 figures

---

Part 1: Nature and role of the hydrolysis products of the methylvinyldichlorosilane in the grafting of silicates in hydrochloric acid and isopropanolThis journal 256, 135 (1978).     

Effect of gleysation on remobilization of radionuclides in waterlogged soils

Joint leaching of iron and other macro- and microelements including radionuclides from radioactively contaminated floodplain soil of the Yenisei River is studied on miniecosystems. In developing anaerobic conditions, the redox potential E_h decreased to +140 mV, causing partial reduction of iron and solubilisation of iron hydrous oxide and organomineral films of the soil. Leaching of stable elements and radionuclides with water proceeds parallel to that of iron. To accelerate reductive mobilization of iron, 0.4% aqueous ascorbic acid was used instead of water as the leaching liquid phase. In this case, E_h approached –60 mV, and the leaching of stable and radioactive elements considerably increased, the effect being most pronounced for plutonium. To cite this article: E.K. Legin et al., C. R. Chimie 7 (2004).

Résumé

Effet du passage en milieu anaérobie sur la mobilisation des radionucléides dans les sols humides. La lixiviation simultanée du fer et d’autres éléments de sols contaminés de la vallée de la rivière Yénései a été étudiée. En imposant des conditions anaérobies, le potentiel redox chute à 140 mV, causant une réduction partielle du fer trivalent et la solubilisation de l’hydroxyde de fer et du film organominéral du sol. Les lixiviations du fer, des autres éléments et, par conséquent, des radionucléides contaminant le sol vont de pair. Pour accélérer la mobilisation réductive du fer, une solution d’acide ascorbique à 0,4% a été utilisée à la place de l’eau. Dans ces conditions, la valeur de E_h approche –60 mV et la lixiviation des éléments augmente considérablement, cet effet étant plus prononcé pour le plutonium. Pour citer cet article : E.K. Legin et al., C. R. Chimie 7 (2004).     

Carbon monoxide promoted reductive elimination of hydrogen from Tp' platinum complexes

Acid-assisted reductive elimination of hydrogen from Tp'PtH(3) and of methane and hydrogen from Tp'PtMeH(2) (Tp' = hydridotris(3,5-dimethylpyrazolyl)borate) is examined herein. Loss of H(2) is observed from solutions containing platinum(IV) complexes of the type Tp'Pt(R)(H)(2) (R = Me, H) upon protonation and addition of a ligand such as CO. Results of kinetic studies on reductive elimination of H(2) and formation of [kappa(2)-(HTp')Pt(R)(L)][BAr'(4)] products from intermediates derived from Tp'Pt(R)(H)(2) precursors are described. Elimination appears to occur from cationic 6-coordinate [kappa(2)-(HTp')Pt(R)(H)(2)(L)][BAr'(4)] species.     

Application of extraction chromatography to the separation of thorium and uranium dissolved in a solution of high salt concentration

Extraction chromatography with commercially available UTEVA resin (for uranium and tetravalent actinide) was applied for the separation of Th and U from control solutions prepared from a multi-element control solution and from sample solutions of solidified simulated waste. Thorium and U in control solutions with 1-5mol/dm(3) HNO(3) were extracted with UTEVA resin and recovered with a solution containing 0.1mol/dm(3) HNO(3) and 0.05mol/dm(3) oxalic acid to be separated from the other metallic elements. Extraction behavior of U in the sample solutions was similar to that in the control solutions, but extraction of Th was dependent on the concentration of HNO(3). Thorium was extracted from 5mol/dm(3) HNO(3) sample solutions but not from 1mol/dm(3) HNO(3) sample solutions. We conjecture that thorium fluoride formation interferes with extraction of Th. Addition of Al(NO(3))(3) and Fe(NO(3))(3), which have higher stability constant with fluoride ion than Th, does improve extractability of Th from 1mol/dm(3) HNO(3) sample solution.     

Origin assessment of green coffee (Coffea arabica) by multi-element stable isotope analysis of caffeine

The delta(13)C(VPDB), delta(2)H(VSMOW) and delta(18)O(VSMOW) values of caffeine isolated from Arabica green coffee beans of different geographical origin have been determined by isotope ratio mass spectrometry (IRMS) using elemental analysis (EA) in the "combustion" (C) and "pyrolysis" (P) modes (EA-C/P-IRMS). In total, 45 coffee samples (20 from Central and South America, 16 from Africa, six from Indonesia, and three from Jamaica and Hawaii) were analysed, as well as three reference samples of synthetic caffeine. Validation was performed by excluding isotope discrimination in the course of sample preparation and determining linear dynamic ranges for EA-P-IRMS measurements. The values for caffeine from green coffee ranged from -25.1 to - 29.9 per thousand, -109 to -198 per thousand, and +2.0 to -12.0 per thousand for delta(13)C(VPDB), delta(2)H(VSMOW), and delta(18)O(VSMOW), respectively. Data evaluation by linear discrimination analysis (LDA) and by classification and regression tree (CART) analysis revealed the delta(18)O(VSMOW) values to be highly significant. Use of LDA on the delta(2)H(VSMOW) and delta(18)O(VSMOW) data from coffee of African and Central/South American provenance led to error rates of 5.7% and 7.7% for adaption and cross validation, respectively.