Advanced Materials Research Vol. 1085

Abstract: Using electronic spectroscopy and fluorescence techniques, the degradation of 2-methyl-4-chlorophenoxyacetic acid has been researched in water under the excitation with UV radiation produced by a KrCl excimer lamp in the presence of “TiO₂, SnO₂, SnO₂/TiO₂ Nanoparticles – Polypropylene Fibrous Carrier” Systems. It has been determined that MCPA phototransformation is most efficient when using the “TiO₂/SnO₂ heteronanoparticles – carrier” system with the concentration of 25/6 mg/g. The results indicate that systems with applied semiconductor particles do not exhibit sorption properties towards МСРА molecules. Therefore, the change in the spectral characteristics of a МСРА water solution after time-exposure and exposure to radiation is only associated with the phototransformations of non-adsorbed МСРА molecules and with the emergence of their photodegradation products.

Abstract: Nanocomposite hydroxyapatite-silver was synthesized using glucose, glycerol and hydrazine chloride as the reductant. Glucose and glycerol promote the formation of 22-25 nm silver nanoparticles on the surface of hydroxyapatite (HA), forming a composite, characterized by intense absorption. One nanoparticle of silver is connected with every particle of HA. Sodium citrate effectively stabilizes this nanocomposite. When using hydrazine hydrochloride as a reducing agent of Ag⁺ ions clusters and small silver nanoparticles (NPs), which are not distinguishable by TEM images, are formed on the surface of hydroxyapatite. This nanocomposite possesses less intense absorption.

Abstract: Acid-base, adsorption and photosorption properties of microparticles surface of magnesium-containing compounds produced by dispersion of natural minerals after exposure to the air were studied. It was revealed that the reduction in predominant basicity of minerals surface in a range of periclase (MgO), brucite (Mg (OH)₂) and magnesite (MgCO₃) can be considered as a result of the presence of iron, silicon and magnesium oxide compounds. Quantum-chemical calculations made during the investigation, the decrease of pressure in the process of long-term contact of Freon 22 with the surface of MgO, irreversible character of adsorption and the absence of fluorine and chlorine-containing products in a gaseous phase give evidence of CFC destructive adsorption on the surface of magnesium oxide. The interaction of chlorine and fluorine derivatives of methane with the surface of aerosol particles from minerals in the darkness and under the influence of sunlight tropospheric radiation was studied. The evaluation of such interactions influence on the process of the Earth troposphere purification from carbon dioxide and dichlorofluoromethane during their adsorption and photosorption on the surface of precipitated aerosol was made.

Abstract: The Importance of this Paper is Determined by the Research of Conditions of Photosorption Processes Occurance on the Surface of Aerosol Particles Resulting in the Removal of Toxic Substances from the Atmosphere. Acid-Base Properties of Oxygen-Containing Calcium Compounds being Components of Troposphere Aerosol Particles were Studied by Methods of Ph-Metry and Hammet’s Indicators. the Basic Properties of the Investigated Compounds Surfaces are Predominant Ones: рН_iis of Calcium Oxide and Hydroxide has a Value of 9.3 – 9.5, and that for Carbonate and Calcite Equals to 12.3-12.4. Indicator Method Distinguishes Three Areas of Spectrum Corresponding to Lewis Base, and Brensted Neutral and Basic Centers. the Intencity of Peaks is much Higher for Ca(OH)₂ and CaO. the Interaction Process of Halogen-Containing Organic Compounds (Freons: 134a, 22 and 12) with Calcium Carbonate Surface under Illumination in Conditions close to Tropospheric Conditions was Studied. it is Shown that the Interaction is the Destructive Photosorption of Freons (134a or 22). the Spectral Dependence of Effective Quantum Yield of Destructive Photosorption is Determined. as a Result of the Interaction Calcium Fluoride and Calcium Chloride are Formed at the Surface.

Abstract: The paper studies phase formation of calcium aluminate prepared by the sol-gel method. The stages of the end products’ formation were proposed using methods of gas chromatography, the thermal and the infrared spectrometric analysis. Dependence of phase composition and the crystalline structure on the annealing temperature of the precursor was revealed.

Abstract: This paper presents the results of study of the surface morphology of thin (~ 200 nm) biocompatible coatings based on titanium oxide and oxynitride deposited by reactive magnetron sputtering for vascular stents made from stainless steel. The analysis of the roughness of the coating surface was performed for describe qualitatively their topography.

Abstract: The X-ray and mass spectroscopy of secondary ions, the phase composition, the distribution of elements in the depth of coating on the basis Ti-Al-N treated by the (Cr+B) ion beam was studied. It was established that the ion implantation of B and Cr in TiAlN coating leads to changes in the chemical composition of the surface layer and the redistribution of the elements in the surface layer. This fact leads to change of tribological properties and microhardness.

Abstract: The processes of nitration of 2-methylimidazole to produce 2-methyl-4(5)-nitroimidazole are considered in this paper. The processes of nitration by mixture of nitric and sulfuric acids and nitrate salts of alkali metals were compared. It was found the nitration of nitrate salts of alkali metal proceeds smoother. The yield of the desired product 2-methyl-4(5)-nitroimidazole was 85 % and 95% in case of nitric acid and nitrate salt.

Abstract: The investigated Mongolian lakes are marked by a large range of trace element concentrations even in very small geographical areas. This work includes the data on major and trace element concentrations along of a series of samples collected in 2009 and 2012. Three geochemical types of lakes have been distinguished within the study area: (1) alkaline soda lakes, (2) chloride lakes with pH < 9.0 and Na-Cl-dominated composition, and (3) sulfate ones with pH < 8. The soda lakes show high concentrations of As, U, F and relatively low salinity. The chloride lakes have higher salinities and one of them was the most saline of all the lakes (Davsan Nuur). These lakes have higher concentrations of Li (up to 82.1 mg/L), Rb (up to 1350 mg/L), Br and Sr. Sulfate rich lakes are far less common in the area. Characteristic trace elements are Mo, Al and Sr. Thermodynamic modeling at 25°C and 1 bar total pressure was performed with the “HCh” code. We considered mineral and solution equilibria in soda lake waters and calculated the main uranium and arsenic species in solutions and bottom sediments of Shaazgay-Nuur lake to offer a possible way of As removal as an undesirable impurity in commercial products.

Abstract: Results of investigation of naphthalene interaction with humic acids of high-moor peat and their fractions are presented in the article. The elemental and structural-group compositions of humic acids of high-moor peat and of their fractions are determined, average values of their molecular masses are found, and their spectral and luminescent properties are investigated. Numerical values of constants of naphthalene interaction with humic acids and their fractions are calculated, and the polarity of naphthalene microenvironment in solutions of humic acids is estimated. The results of investigations suggest that the maximum affinity of naphthalene is observed to the fraction of hematomelanic acids and that the naphthalene microenvironment in solutions of the given fraction is polar.