Sorption and Catalytic Activity of Adsorbent-Catalyst Based on Montmorillonite Modified with Cr(III) and Cu(II) Mixed Oxides

The sorption properties of mixed adsorbent-catalyst based on high-silica zeolite and montmorillonite modified with mixed oxides of Cr(III) and Cu(II) with respect to organic compounds of various classes were studied, and the optimal dynamic conditions of its operation were determined.     

Metal Complexes as Promising Ionophores for the Production of Anion-Selective Electrodes with Improved Selectivity

The possibility of producing liquid anion-selective electrodes with improved selectivity based on the capability of the metal atom to coordinate the analyzed anions is illustrated using numerous examples. The subjects under consideration were electrodes based on high-stable lipophilic metal complexes with polydentate organic ligands, electrodes based on lipophilic organometallic compounds capable of coordinating anionic ligands, and electrodes based on higher quarternary ammonium salts that respond to lipophilic anionic metal complexes, in particular, the electrodes with the ligand function. The theoretical principles underlying the above electrode operation are discussed. Methods for optimizing the composition of the membrane and of the studied solution are suggested with the aim to improve the selectivity of the electrode.     

Enantioselective, potentiometric membrane electrodes based on cyclodextrins: application for the determination of R-baclofen in its pharmaceutical formulation

Two enantioselective, potentiometric membrane electrodes based on α- and γ-cyclodextrins were proposed for the assay of R-baclofen. The slopes of the electrodes were 59.50 and 51.00 mV/pR-baclofen for α- and γ-cyclodextrin-based electrodes, respectively. The detection limits of the proposed electrodes were 7 × 10⁻⁹ mol l⁻¹ for α-cyclodextrin-based electrode and 1.44 × 10⁻¹⁰ mol l⁻¹ for γ-cyclodextrin-based electrode. The enantioselectivity was determined over S-baclofen. The proposed electrodes can be employed for the assay of R-baclofen raw materials and its pharmaceutical formulation, Norton-Baclofen^® tablets. The surfaces of the electrodes are stable and easily renewable by polishing on alumina paper.     

Adsorption and Structural Properties of Montmorillonite Pillared by Cr(III) and Cr(III)–Cu(II) Hydroxocomplexes

The sorption and structural parameters and thermal stability of montmorillonite pillared by Cr(III) polyhydroxocomplexes and heteronuclear Cr(III)–Cu(II) polyhydroxocomplexes were investigated. It was shown that the introduction of intercalating Cr(III) and Cr(III)–Cu(II) agents into the montmorillonite increased the value of the first basal reflection (d ₀₀₁) up to 1.85 nm in the first case and up to 1.98 nm, in the second. The dependence of the values of d ₀₀₁and specific surface area on the OH^–/Cr³⁺ratio was found, which is retained during the calcination of the samples up to 500–800°C. The sorption ability of the prepared samples with respect to acetone, ethanol, benzene, toluene, and water was investigated.     

Macrocyclic antibiotics as chiral selectors in the design of enantioselective, potentiometric membrane electrodes for the determination of l- and d-enantiomers of methotrexate

Three enantioselective, potentiometric membrane electrodes (EPMEs) based on macrocyclic glycopeptide antibiotics—vancomycin and teicoplanin (modified or not with acetonitrile)—were proposed for the determination of l- and d-enantiomers of methotrexate (Mtx). The linear concentration ranges for the proposed enantioselective membrane electrodes were between 10⁻⁶ and 10⁻³ mol l⁻¹ for l- and d- methotrexate. The slopes of the electrodes were 58.00 mV/pl-Mtx for vancomycin-based electrode; 57.60 mV/pd-Mtx for teicoplanin-based electrode and 55.40 mV/pd-Mtx for teicoplanin modified with acetonitrile-based electrode. The detection limits of the proposed electrodes were of 10⁻⁸ mol l⁻¹ magnitude order. The surfaces of the electrodes are stable and easily renewable by polishing on alumina paper. All proposed electrodes proved to be successful for the determination of the enantiopurity of Mtx as raw material and of its pharmaceutical formulations (tablets and injections).     

Synthesis and Properties of Modified Fillers Based on Calcium and Magnesium Carbonates

A possibility of modifying natural carbonate fillers for paint and varnish industry by solutions of salts of some nonferrous metals was studied. Reactions of carbonates with metal ions and physicotechnical properties of the resulting materials were considered.     

Hydrothermal Synthesis of Porous Al2O3/Al Metal Ceramics: I. Oxidation of Aluminum Powder and Structure Formation of Porous Al(OH)3/Al Composite

The properties of ASD-1 aluminum powder and its oxidation with water at 100°C were studied. It was found that the microstructure of a surface oxide film and the conditions of oxidation significantly affected the dynamics of changes in the pH of the solution and in the degree of aluminum conversion into the hydroxide. Experimental data on the oxidation in combination with electron-microscopic measurements and the determination of adsorption and texture characteristics resulted in the conclusion that colloid-chemical processes, which include the dissolution of aluminum and the formation and precipitation of the hydroxo complexes of aluminum, are fundamental for the synthesis of porous metal ceramics.     

Sorption Properties of α-Aluminum Oxide Modified with Decationized Silica Sol

The method of sorption of tetrachloromethane vapor at the solid/gas interface was applied to study the sorption and structural properties of a mesoporous aluminum oxide material obtained by deposition of amorphous hydrated silicon(IV) oxide onto -aluminum oxide particles submerged in decationized silica sol.     

Selective Sorption of Fe(III) Ions from Ni(II)-Fe(III) Mixtures with Chemisorbents

Selective recovery of Fe(III) ions from two-component nitrate solutions of Fe(III) and Ni(II) with synthetic nickel phosphate, natural chalk, and natural tripoli were studied. The mechanism of selective action of chemisorbents was considered, and high efficiency of the materials considered was demonstrated.     

Hydrothermal Synthesis of Porous Al2O3/Al Metal Ceramics: IV. Synthesis of Composite Porous Ceramics in the Presence of Microporous and Mesoporous Adsorbents

The formation of the structure and properties of mesoporous composite ceramics based on an ASD-1 aluminum powder and commercial adsorbent powders (zeolites and active alumina) was studied. It was found that the mechanism of the formation of contacts between the particles of commercial adsorbents and aluminum is analogous to the mechanism of synthesis of an Al(OH)₃/Al composite. The dissolution of aluminum and the precipitation of the hydroxo complexes of aluminum from solution to the region of interparticle contacts are responsible for this mechanism. The resulting composite ceramics exhibited a polydisperse pore structure and high values of mechanical strength, gas permeability, and thermal conductivity; it can be used as a block adsorbent and catalyst support.