Fine Chemical Technologies (E-Journal) / Тонкие химические технологии
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СЕНСОРЫ НА ОСНОВЕ ФОТОННЫХ КРИСТАЛЛОВ
Get PDFChemical sensors are one of the most demanded tools of modern analytical chemistry. Recently, devices based on the registration of color changes upon reflecting visible irradiation from the surface of so-called "photonic crystals" (PC) have begun to be used for analytical chemistry purposes. Some advantages of this method are the possibility of visual detection of substances, relatively high sensitivity, and the ability to change the properties of such sensors by varying the element base of the PC. The effect of various mechanical, electrical, optical, chemical and other factors on the objects under study leads to additional changes in the spectral responses from the PC surface with deposited materials. A sufficiently short response time allows the use of such sensors for the operational control of various substances with a high degree of hazard. In the long term, such devices can be used as test systems for the detection and analysis of a wide class of chemical and biological substances. This review is devoted to various types of sensors based on photonic crystals. It deals with: photonic crystals of natural and synthetic origin; various possible structures of PC; causes of the appearance of characteristic optical properties; detection of mechanical, thermal, electrical, magnetic and optical effects on the PC, as well as effects on organic compounds of various classes; areas of application of sensors based on PC
ПОВЕДЕНИЕ РЕДКОЗЕМЕЛЬНЫХ МЕТАЛЛОВ ПРИ ГИДРОМЕТАЛЛУРГИЧЕСКОЙ ПЕРЕРАБОТКЕ ПИРОХЛОР-МОНАЦИТ-ГЁТИТОВЫХ РУД
Get PDFThe article is dedicated to finding out the specific features of the behavior of rare-earth metals in hydrometallurgical processing of pyrochlore-monazite-goetite ores of the Chuktukonsky ore field is shown in the work. Chuktukonsky ore field is a potential source of rare earth metals. The mentioned ores are practically unenforceable. Hydrometallurgical methods for their complex processing were suggested. Agitational and autoclave nitric acid leaching depending on such technological parameters as temperature, HNO3 concentration, process duration, S:L ratio and the use of H2O2 were studied. The possibility of transferring manganese (that is present in a significant amount in the ore) into a nitric acid solution by hydrogen peroxide was considered. Based on the results of the conducted studies, the distribution of REM in the products of the hydrometallurgical conversion of pyrochlore-monazitegoetite ore was estimated. It was found out that incomplete opening of the ore material was observed during agitational leaching: average REM recovery into the solution is 60%. The study made it possible to solve the problem of purifying nitric acid solutions from phosphorus that hinders the subsequent extraction and separation of rare earth metal ions forming strong complexes with rare earths. Removal of phosphorus from the solution was achieved by conducting the process under pressure at elevated temperatures (200-230 0C). It was found that the optimal decomposition conditions ensuring the transfer of almost 99% of the REM into the nitric acid solution are: 25% solution of HNO3, ore size - 0.071 mm; 5% by volume H2O2; t(160 0С) = 1 h; t(230 0С) = 1 h, gradual temperature increase from 160 to 230 0С; S:L = 1:8. Autoclave nitric-acid leaching allows selecting rare earth metals from the main part of iron, phosphorus and niobium
ДИОКСИДЫ ЦИРКОНИЯ И ГАФНИЯ, СТАБИЛИЗИРОВАННЫЕ ОКСИДАМИ РЕДКОЗЕМЕЛЬНЫХ ЭЛЕМЕНТОВ (Y, Sc, Er): НОВЫЕ МЕТОДЫ СИНТЕЗА И СВОЙСТВА
Get PDFThe results of elaborating a method for the synthesis of zirconia and hafnia doped by rare earths (yttrium, erbium and scandium) by using low-hydrated hydroxides of zirconium and hafnium as precursors are reported. The low-hydrated zirconium and hafnium hydroxides were prepared using the heterophase reaction. The physicochemical properties (including sorption properties) of low-hydrated zirconium and hafnium hydroxides ZrxHf1-x(OH)3÷1O0.5÷1.5·0.9÷2.9H2Owere studied. The scheme of thermal decomposition of low-hydrated hydroxides in air was determined. The sorption properties of the low-hydrated hafnium hydroxide are less pronounced owing to the lower amount of sorption centers, in this case, hydroxo and aqua groups. The sequence of stages of thermal decomposition of rare earth acetates was elucidated. Single-phase zirconia and hafnia doped by rare earths (yttrium, erbium and scandium) were obtained. The parameters of the elementary lattice were calculated for each phase. It was established that the stabilization of zirconium dioxide with yttria leads to the formation of interstitial solid solutions based on tetragonal zirconia (in the case of the composition Y2O3×4ZrO2 - cubic modification), with erbium oxide - interstitial solid solutions based on cubic zirconia; with scandium oxide - solid solutions based on tetragonal zirconia. The article presents the results of measuring electrical conductivity
ИССЛЕДОВАНИЕ РАЗЛИЧНЫХ ИЗОМНОГООБРАЗИЙ В ЧЕТЫРЕХКОМПОНЕНТНЫХ СИСТЕМАХ, СОДЕРЖАЩИХ БИАЗЕОТРОПНЫЕ БИНАРНЫЕ СОСТАВЛЯЮЩИЕ
Get PDFIn the present work, an analysis of the mutual arrangement of a number of iso-manifolds in the concentration tetrahedron formed by the components of the separated mixture and an additional substance, an extractive agent, was carried out to estimate the possibility of separating three-component mixtures containing biazeotropic constituents by extractive rectification. The objects of research were four-component systems formed by ternary constituents (butyl propionate (BP) - propionic acid (PA) - butyl butyrate (BB), butyl propionate - propionic acid - butyric acid (BA), butyl butyrate - butyric acid -butyl propionate, butyl butyrate - butyric acid -propionic acid) of the commercially important BP-PA-BB-BA system, and the extractive agent sulfolane. Using the results of the computational experiment based on mathematical model NRTL-HOC we obtained complete data on the vapor-liquid equilibrium in binary, three- and four-component systems. The structures of liquid-vapor phase diagrams were obtained, and thermodynamic-topological analysis of all four-component systems was carried out. The mutual arrangement in the concentration tetrahedron of manifolds of relative volatility (equal to 1) of the components, reflecting the evolution of pseudo-azeotropes in sections with a constant concentration of the extractive agent; pseudo-ideal manifolds along which the activity coefficients of the components of the base (separated) mixture are equal to each other; isothermo-isobaric manifolds generated by Bancroft points in binary azeotropic constituents were determined. We established that it is possible to separate the studied three-component mixtures by extractive rectification using sulfolane
МЕТОД КОНЕЧНЫХ ЭЛЕМЕНТОВ (МКЭ): ПРИМЕНЕНИЕ К МЕХАНИКЕ СПЛОШНОЙ СРЕДЫ И ТЕПЛОПЕРЕДАЧЕ
Get PDFIn this paper the finite element method (FEM) is used to solve three problems that are of the paramount importance in Chemical Engineering. The first problem is related with the bidimensional flow of an ideal fluid around a cylindrical body, and the objective is to determine the velocity distribution of the flow. To model the flow, the potential formulation is used to obtain an analytical solution, and then, the approximated solution obtained by using FEM is compared with the analytical solution. From this comparison, it is deduced that both solutions have a good agreement. The second problem is the calculation of the temperature profile in a two-dimensional body with specified boundary conditions. This problem is modeled by the two-dimensional Laplace equation, and from the problem data and using variables separation, an analytical solution was obtained. Then, FEM was used to obtain an approximate solution and compared with analytical ones. Besides, from this comparison, it is concluded that both solutions agree. Finally, in the third problem the temperature distribution in a bidimensional body with internal heat generation is studied. This problem is modeled by Poisson equation in two dimensions, but due to the boundary conditions and the complications that arise by adding some heat sources in the final FEM discretization, the problem does not have an analytical solution. However, the analysis of FEM solution indicates that this solution is correct
ВЛИЯНИЕ ПОЛИМИКСИНА В НА ФОРМИРОВАНИЕ БИОПЛЕНКИ БАКТЕРИЕЙ Methylophilus quaylei НА ПОЛИПРОПИЛЕНЕ И ТЕФЛОНЕ
Get PDFHere we examined the influence of polymyxin B, a lipopeptide antibiotic, on planktonic growth and biofilm of streptomycin-sensitive and streptomycin-resistant isogenic strains of bacteria Methylophilus quaylei on polypropylene and Teflon. Biofilm formation was quantified using crystal violet staining, determined by colony-forming unit and examined by light microscopy. It was found that of bacterial surface hydrophobicity affects the biofilm formation: biofilm formation of Methylophilus quaylei MT strain was better on such hydrophobic materials as Teflon and polypropylene. The minimum inhibitory concentration of polymyxin B for the used strains in planktonic and biofilm form was 1 μg/ml. The sublethal Polymyxin B in the concentration of 0.01 μg/ml stimulates biofilm formation and exhibits antibiofilm properties at the concentration of 0.10 μg/ml. Synergistic effect of polymyxin B and streptomycin on streptomycin-resistant strain M. quaylei SM was found.Исследовано влияние липопептидного антибиотика полимиксина В на рост чувствительного и резистентного к стрептомицину изогенных штаммов метилотрофной бактерии Methylophilus quaylei в планктоне и биопленке на полипропилене и тефлоне. Интенсивность образования биопленок определяли по окрашиванию кристаллическим фиолетовым, колониеобразующей способности, а также методом световой микроскопии. Обнаружено влияние гидрофобности клеточной поверхности бактерий на способность образовывать биопленки. На пластинах из тефлона и полипропилена более интенсивную биопленку образует штамм Methylophilus quaylei MT с гидрофобной поверхностью. Минимальная ингибирующая концентрация полимиксина В для изученных штаммов и в планктонной, и в биопленочной форме составила 1 мкг/мл. Полимиксин В в сублетальной концентрации 0.01 мкг/мл стимулирует образование биопленок, а в концентрации 0.10 мкг/мл проявляет антибиопленочные свойства. Обнаружено синергидное действие полимиксина В и стрептомицина на резистентный к стрептомицину штамм M. quaylei SM
ИСПОЛЬЗОВАНИЕ МНОГОТОННАЖНЫХ ТЕХНОГЕННЫХ ОТХОДОВ ДЛЯ СОЗДАНИЯ БИТУМНЫХ КОМПОЗИТОВ С УЛУЧШЕННЫМИ ПОКАЗАТЕЛЯМИ ДОЛГОВЕЧНОСТИ
Get PDFWith the goal of searching effective methods of industrial wastes recycling, filler systems for bituminous binders in road building have been proposed. For the first time in the world, the product of recycled tire rubbers, which is an active powder of discretely devulcanized type of rubber in addition to waste of sulfur produced in technological processes of oil refining, natural gas, etc., have been tested in order to improve the quality of bitumen binders. The rheological properties and fatigue life of the sulfur-bitumen binder have been investigated according to the linear amplitude sweep test (LAS) by using a Smart Pave dynamic shear rheometer (Physica MCR series, Anton Paar, Austria). A technique for preparing samples of sulfur-containing binders has been developed based on the results of photomicrographs analysis obtained by optical microscopy. It has been done to study their fatigue cracking resistance. The analysis of the influence of sulfur and elastic filler on fatigue life has showed that the rise of the quantity of cycles up to fatigue damage of binder samples by the factor of 3-5 (strain of 5% and 2.5%) is due to crumb rubber concentration. The addition of sulfur to ternary systems bitumen/sulfur/elastic filler enables saving energy resources as a result of the possibility of manufacturing sulfur-extended asphalt at lower temperatures
ИСПОЛЬЗОВАНИЕ АКТИВИРОВАННОГО МЕДНОГО МИКРОЭЛЕКТРОДА ДЛЯ ВОЛЬТАМПЕРОМЕТРИЧЕСКОГО ОПРЕДЕЛЕНИЯ СПИРТОВ
Get PDFA method for fabricating a copper microdisk electrode of an original design based on 50 μm diameter wire sealed in borosilicate glass is described. The electrochemical properties of the copper microelectrode were studied by the method of steady-state voltammetry in a 2 M NaOH solution in the potential range from -1.1 to 0.8 V (versus saturated Ag/AgCl-electrode). In order to improve the electrochemical response a method for two-stage electrode activation based on a copper dissolution / redeposition procedure followed by polarization in an alkaline medium is suggested. Morphological and physico-chemical changes on copper surface after activation were examined by atomic force microscopy and X-ray photoelectron spectroscopy. After this procedure, the electrode showed a heterogeneous morphology with coarse texture and high roughness parameters, and a layer of catalytically active Cu(III) species was formed on copper surface. The best results were achieved with an activation time of 60 s and a polarization potential of -0.3 V. The effectiveness of the activation procedure was tested during the chronoamperometric determination of methanol, ethanol and ethylene glycol. Factors affecting the formation of the analytical signal of alcohols were studied, and optimal conditions of amperometric measurements were selected on their basis. Under optimal conditions, the metrological characteristics of the method were determined. The peak current response increases linearly with alcohols concentration over the range 0.01 - 0.45 M (0.04 - 3% v/v). The repeatability of the electrode response was evaluated as 3.8% (n = 10). The activated copper microelectrode was used for the determination of ethanol in pharmaceutical and other products
ПРОМЕЖУТОЧНОЕ ЗАДАННОЕ РАЗДЕЛЕНИЕ ПРИ РЕКТИФИКАЦИИ ЧЕТЫРЕХКОМПОНЕНТНЫХ СМЕСЕЙ
Get PDFConditions of sharp distillation were considered for zeotropic quaternary system (two pairs of components are characterized by relative volatility close to 1) and systems with one (with minimum or maximum boiling point) and two (with minimum and maximum boiling point) binary azeotropes. Regions of compositions for which sharp distillation is effective (distillate and bottom flows don't contain common components) were determined on the basis of analyzing diagrams of unit manifolds of distribution coefficients (distribution coefficients of two components are higher than one, and those of another two components - lower than one). This kind of separation can be recommended if it doesn’t cause an increase in the number of apparatuses in the separation flowsheet. If the system contains azeotropes of saddle type that can generate separatric manifolds, the possibility and expedience of sharp separation decreases. The conclusions were confirmed by simulation of the distillation process in AspenPlus V.10.0 for real and industrially important quaternary systems: ethyl acetate - benzene - toluene - butyl acetate; acetone - methanol - ethanol - propanol-2; methyl acetate - methanol - acetic acid - acetic anhydride and cyclohexene - cyclohexane - cyclohexanone - phenol. Mathematical modeling was carried out using local compositions models Wilson and NRTL-HOC. The relative error of vapor-liquid equilibrium description is less than 4%. The vapor-liquid equilibrium was simulated, a phase diagram was constructed and analyzed, the parameters of sharp distillation column operation (the number of stages, the feed-stage and reflux ratio) were determined for all systems. The effectiveness of using sharp distillation for the system with phenol was confirmed for a wide range of compositions
КОМПЛЕКСЫ СЕРЕБРА, СВИНЦА, КАЛЬЦИЯ С БИСФОСФОНОВЫМИ ЛИГАНДАМИ
Get PDFIt is interesting in chemical terms and promising in the applied production of new complexes of metals with bisphosphonic ligands with a popular set of consumer properties. To date, little has been studied chemistry of bisphosphonic acid complexes with the basic structure of 1-hydroxymethylene-bisphosphonic acid with a side chain containing 11 carbon atoms and ending with an amino group. The main objective is to obtain new bisphosphonates of s-, p -, d - and f-elements, their characterization by a complex of physical and chemical research methods (NMR and IR spectrometry, RSA, DTA, optical microscopy, laser diffraction) and to identify new applications of bisphosphonic acids and their salts. In the course of the work, complexes of Ag, Pb, Ca, with 1-hydroxymethylene-bisphosphonic acid (H2N(CH2)xC(OH)(H2PO3)2) and its derivatives, the side chain ends with an amino group, its length is 11 carbon atoms. Crystal structures of metal-bisphosphonate complexes with the general formula H2N(CH2)10C(OH)(HPO3)xM (M = Ag, Pb, Ca) were determined. The complexes were characterized by IR spectroscopy and 31P solid-state NMR spectroscopy, RSA. The areas of practical use of the complexes are outlined. It is shown, by the example of wastewater in Kuopio, Finland, that bisphosphonic acids can be used for wastewater treatment of enterprises from heavy metals (M =Pb, Zn, Cd, etc.)