SYNTHESIS AND STUDY OF GAS-SENSITIVE NANOSTRUCTURES OF THE Zn-Sn-O SYSTEM

Наностержни оксида цинка синтезированы гидротермальным методом. Проведена обработка полученных образцов в водно-спиртовом растворе станната калия и мочевины при 170°С в течение 30 и 60 минут. В результате получены наноструктуры Zn - Sn - O. Химический состав поверхности образцов ZnO и Zn - Sn - O исследован с помощью рентгеновской фотоэлектронной спектроскопии. Проанализирована их чувствительность к парам изопропилового спирта (1000 мд) при температурах 120 °С, 180°С, 250 °С. Показано перераспределение электронной плотности при формировании композитных наноструктур Zn - Sn - O, проявляющееся в химическом сдвиге пиков O1s и Zn2p. Это свидетельствует о перестроении химических связей при замещении атомов цинка оловом. Обнаружено, что чувствительность композитных структур к парам изопропилового спирта значительно превышает чувствительность ZnO во всем исследуемом температурном диапазоне. Улучшение газочувствительных свойств связано с наличием в образцах системы Zn - Sn - O поверхностных центров различного типа, принимающих участие в адсорбции и окислении изопропилового спирта. Zinc oxide nanorods were synthesized by the hydrothermal method. The obtained samples were processed in an aqueous-alcohol solution of potassium stannate and urea at 170 °C during different times. As a result, Zn - Sn - O nanostructures were obtained. The surface chemical composition of ZnO and Zn - Sn - O was studied using the X-ray photoelectron spectroscopy. Its sensitivity to vapors of isopropyl alcohol (1000 ppm) at 120 °C, 180 °C, 250 °C was analyzed. The electron density redistribution during the Zn - Sn - O composite nanostructures formation manifests itself in the chemical shift of the O1s and Zn2p peaks. It confirm the rearrangement of chemical bonds when zinc atoms are replaced by tin ones. It was found that the sensitivity of composite structures to isopropyl alcohol vapors significantly exceeds that of ZnO in the entire temperature range under study. The improvement of gas-sensitive properties is associated with the presence of various types of surface centers in the Zn - Sn - O samples that participate in the adsorption and oxidation of isopropyl alcohol.

Оbtaining isovaleric acid extraction from plant raw material

The paper presents a mathematical description of the process of obtaining isovaleric acid by the method of extraction of roots and rhizomes of valerian, taking into account its chemical structure and the nature of the extractant. The traditional case of the extraction process, the straight line of equilibrium in the case of using an aqueous alcohol solution as an extractant and the unconventional case of using desalinated water as an extractant, which is represented by a convex equilibrium line, is substantiated. The cause of the unconventional case is the phenomenon of formation of associations between diphilic molecules of isovaleric acid and dipole molecules with water. The possibility of using ion exchange was investigated to isolate isovaleric acid from the extract of biologically active compounds. The identity of isovaleric acid obtained in this way by the gas method was confirmed chromatography.

DETECTION OF FALSIFICATION OF HORILKA BY ADMITTANCE SPECTROSCOPY

The methods of quality control of horilka by electrical parameters, in particular, dielectric constant, specific conductivity, and imitation components are analyzed. The research results of individual samples of alcohol solutions and horilkas of different brands by the method of admittance spectroscopy were also analyzed. Based on this, methods for detecting falsification of horilka products by the method of admittance spectroscopy are proposed. The reactive component of the control object's ad is selected as an informative parameter. Two types of falsification are analyzed. The first is the falsification of the original horilka by replacing it with an aqueous-alcohol solution. The second - by replacing one brand of horilka with another. The analysis of the obtained results of researches of two types of objects on reactive components of their admittance in the frequency range 100 Hz100 kHz showed the following: characteristic features of dependencies of reactive components on frequency are revealed; they have been found to have extreme values at different frequencies. The reactive component of the admittance of aqueous-alcohol solutions reaches an extreme value at the beginning of the range. The same component of the original horilkas of different brands has extreme values at the end of the range. Based on this, methods for prompt detection of falsifications are proposed.

Spectral study of thione-thiol tautomerization of thiourea in aqueous alcohol solution

In this work we studied the equilibrium of thione–thiol tautomerization by Raman and UV spectroscopies. This type of tautomerization influences on the course and direction of the reaction between thiourea and other organic compounds. The studies were carried out in water and aqueous alcohol medium. Мethanol, ethanol, propanol-1 and propanol-2 were used as alcohols. Hydrochloric acid was used to protonate thiourea in water and aqueous alcoholic solutions. UV spectroscopy made it possible to establish the tautomer ratio in water and aqueous alcohol solutions as the ratio of the intensities of absorption bands at 236 and 200 nm. There is an increase in the content of the thiol form and a decrease of the thione form observed in the row water-methanol-ethanol-propanol-isopropyl alcohol. The addition of hydrochloric acid to the thiourea water or aqueous alcohol solutions leads to the increase of the thione form and to the decrease of the thiol form in the composition. The thione form of thiourea can be determine by Raman spectra of –C=S group. The thiol form of thiourea is difficult to detect by Raman spectroscopy due to the overlap of the –S–H bond absorption band with alcohols absorption bands.

Effect of acidic aqueous alcohol solution on template sol-gel synthesis of phosphorescent hexagonal mesoporous silica film nanocomposite

Here novel mesoporous silica film nanocomposite with a hexagonal structure is successfully synthesized by using phosphorescent columnar assembly of a trinuclear gold(I) pyrazolate complex bearing amphiphilic side chains [Au3Pz3], formed via a weak AuI-AuI metallophilic interaction, as a functional template in the sol-gel synthesis. By controlling the molar ratios of alcohol to acid in an acidic aqueous alcohol solution, the sol-gel synthesis of columnar assembled [Au3Pz3] with a silica source can provide highly ordered hexagonal mesoporous silica film composite [Au3Pz3]/silicahex consisting one-dimensional molecular assembly in the nanoscopic channels. The as-fabricated silica film nanocomposite [Au3Pz3]/silicahex with red emission have phosphorescent properties with luminescence emission centered at 693 nm (ext = 276 nm; Stokes shift,  = 417 nm) and lifetime at 7.8 s (ext = 266 nm, em = 690 nm).

Catalyst-Free and Highly Selective N,N-Diallylation of Anilines in Aqueous Phase

A highly selective diallylation reaction of anilines with allyl bromide was achieved in aqueous alcohol solution in the presence of potassium carbonate and without the use of any catalyst. The reaction tolerates a wide range of functionalities, and various tertiary amines were obtained in the yield of up to 99% with complete conversion of anilines.

Conductive and Mechanical Properties of Graphite Nanoplatelets/PVC Nanocomposites Prepared by Melt Blending

Graphite nanoplatelets (Nano-Gs) were prepared by treating the expanded graphite with sonication in aqueous alcohol solution, and then the Nano-Gs/ PVC nanocomposites were fabricated by way of melt blending. The structure of Nano-Gs was characterized by FTIR and SEM, the conductive and mechanical properties of the Nano-Gs/ PVC nanocomposites were also studied. Results show that with a small amount of functional groups distributing on the surface, Nano-Gs have a thickness ranging 30-100nm and a diameter ranging 3-20μm, and disperse randomly in PVC resin matrix. The Nano-Gs/ PVC nanocomposites exhibit low volume resistivity of 104Ω•cm when the mass fraction of Nano-Gs goes beyond 10%, and the percolation threshold of the nanocomposites is as low as 6wt%. Furthermore, with the increase of the filled Nano-Gs, both the tensile strength and notched impact strength of the nanocomposites increase first and then decrease, and achieve the maximal value simultaneously with the addition of 1 wt% Nano-Gs, which increase by 8% and 29% respectively compared with the pristine PVC.