Voprosy khimii i khimicheskoi tekhnologii (Issues of Chemistry and Chemical Technology)

11-18

Authors: A.I. Bondarieva, V.Yu. Tobilko, Yu.M. Kholodko, B.Yu. Kornilovych, N.A. Zahorodniuk

We studied the main physicochemical features of removing of arsenate from contaminated waters utilizing stabilized nanoscale iron. An inorganic kaolinite matrix was used for stabilization. The structure of adsorbents was studied using some physicochemical methods (X-ray powder diffraction and the low-temperature N2 adsorption-desorption method). It was found that the efficiency of the removal of arsenic (V) ions depends on the weight ratio of iron nanopowder to kaolinite, whereas it does not depend on the pH of the water systems in a wide range. Kinetics data were analyzed using pseudo-first-order and pseudo-second-order models. It was stated that the removal of arsenic by iron-containing composites based on kaolinite occurs relatively rapid. The adsorption kinetic was appropriately described by the pseudo-second-order model, indicating the high affinity of arsenates with the surface of the iron-containing nanocomposite. The results demonstrated that the obtained materials have a much higher sorption capacity to As(V) ions than natural silicates. The Langmuir and Freundlich isotherm equations provided good fittings for the experimental sorption data. It was shown that the sorbents based on stabilized nanoscale iron effectively remove toxic arsenic ions from contaminated water.

29-38

Authors: H.R. Gurbanov, M.B. Adigezalova

For the first time in the laboratory, the physical and chemical characteristics of the model oil sample, the composition, and relative amounts of normal alkanes with carbon atoms from C8 to C60 were determined by high-temperature liquid-gas chromatography. When Difron-4201 is added to the model oil, seven carbon atoms are displaced in the direction of the lower molecular weight distribution of paraffin hydrocarbons in the sediment. The effect of the Difron-4201 additive on the group composition of model oil and oil sediments obtained at different temperatures of the "cold finger" was studied. It was found that with the addition of the additive and with a decrease in the temperature of model oil and "cold pipe", the number of paraffin hydrocarbons in the group composition of sediment increases and the amount of resin and asphaltenes decreases. Microanalysis of the structure of asphaltene–resin–paraffin sediments obtained after the addition of the additive showed that the model oil sediments, separated at 30/1500C and containing large amounts of high-molecular paraffin hydrocarbons, resin, and asphaltene components, have the highest proportion of amorphous structures. An increase in the share of dendritic modification of the crystalline structure is characteristic for paraffin hydrocarbons in sediments obtained with the addition of 900 g/t "Difron-4201" additive.

47-53

Authors: V.S. Dutka, Ya.P. Kovalskyi, G.G. Midyana

The adsorption of oligomeric peroxide of sebacic acid and benzoyl peroxide on aerosils and magnesium oxide is studied. The parameters of the adsorption processes are determined. It is shown that the adsorption occurs via formation of hydrogen bonds between surface OH-groups of adsorbents and peroxide groups. The adsorption of benzoyl peroxide on the surface of aerosils and magnesium oxide is low. The thermal decomposition of oligomeric peroxide of sebacic acid and benzoyl peroxide in the presence of aerosil is investigated. The thermal decomposition of oligomeric peroxide of sebacic acid in the presence of aerosils is faster than in a homogeneous system. The corresponding activation energy increases as the aerosil content in the system decreases. In contrast to oligomeric peroxide of sebacic acid, aerosils has no effect on the thermal decomposition rate of the benzoyl peroxide. The polymerization of styrene in the presence of aerosil leads to the formation of a mineral-polymer composite. An increase in aerosil content in the polymerization system leads to a decrease in the rate of polymerization of styrene.

60-67

Authors: A.V. Klymenko, V.I. Sytar, I.V. Kolesnyk, V.V. Anisimov

The adhesive properties of composite coatings based on poly (m-, p-phenylene isophtalamide) with widely used antifriction fillers (copper phthalocyanine, molybdenum disulfide, graphite and boron nitride) were investigated. The results of measurements of adhesive characteristics are obtained by means of cross cutting test and quantitative peel test. Introduction of fillers leads to an increase in the adhesive strength of coatings, while the type of a filler virtually does not affect the adhesive properties. When the filler content is 20 wt.% and more, the cohesive fracture of the coating occurs during the peel test. Introduction of the fillers significantly reduces the value of internal stresses that is accompanied by an increase in the adhesion strength. By way of example of graphite, we showed that an increase in the particle dispersion of the filler results in an increase in the value of adhesion strength of composite coatings, but does not cause any fundamental changes in the character of the dependence of adhesion strength on the filler concentration.

76-82

Authors: V.I. Maksin, R.V. Lavrik, T.I. Ushchapivska, O.V. Petrenko

Single crystals of Na2Mn3(P2O7)2 compound have been first obtained during the examination of interaction in the Na2O–P2O5–Mn2O3–NaF (10 wt.%.) system in the fluxes with Na2O:P2O5 molar ratios ranging from 0.52 to 0.76 (saturated with manganese(III) oxide 25.0–32.0 wt.%) at the temperatures of 960–8800С. Optimum conditions for the synthesis and growing of single crystals of Na2Mn3(P2O7)2 compound have been determined. Complete X-ray diffraction analysis of the synthesized phosphate Na2Mn3(P2O7)2 has been performed. According to its structure, the double phosphate Na2Mn3(P2O7)2 belongs to the triclinic crystal system, spatial grid P ; lattice parameters are as follows: a=5.359 Å, b=6.563 Å, c=16.299 Å, =81.290, =82.700, =72.440, V=538.23 Å3, Z=4, сcalc= 3.447 g cm–3. Structural features of synthesized phosphate have been determined. The structure is composed of continuous chain of distorted octahedra [MnO6] spacing along the direction ob. Diphosphate groups of tetrahedra [РО4] divide the chains [MnO6] and also run along ob direction. Pairwise linked pentagonal bipyramids of sodium divide the "units" of polyhedral of manganese and phosphorus, filling the channels along oy axis. The crystalline structure of Na2Mn3(P2O7)2 includes three nonequivalent, according to their crystallography, octahedra of manganese with slightly distorted form. The compound has been studied using X-ray diffraction and X-ray phase analyses, differential thermal analysis, IR spectroscopy and complete chemical analysis.

88-94

Authors: I.V. Raspertova, D.M. Khomenko, Z.D. Uzakbergenova, R.O. Doroshchuk, R.D. Lampeka

New coordination compounds of -phenyl-N-methylnitrone with Cu2+, Mn2+, Ni2+, and UO22+ were synthesized. Complexes were studied by means of IR, NMR and UV-Vis spectroscopies. The crystal and molecular structure of uranyl complex with -phenyl-N-methylnitrone was determined by X-ray diffraction study. The monodentate nitrone ligands are coordinated to the metal ion via oxygen atom. The coordination polyhedron of uranium is a distorted hexagonal bipyramide. It was shown that there is dynamic process in the acetone solution in the temperature range of 203–297 K. The ligand exists as a trans-isomer for both present forms of organic ligand by the NOE difference. Dimeric copper(II) benzoate was obtained via recrystallization of the copper complex with -phenyl-N-methylnitrone from methanol solution. According to X-ray diffraction analysis, the environment of each of the copper atoms is octahedral. The coordination sphere is formed by six oxygen atoms. Three anions of benzoic acid are coordinated bidentate-bridged through oxygen atoms of the carboxyl group, while one molecule of benzoic acid is coordinated monodentatically through the carboxyl oxygen atom.

11-16

Authors: F.I. Danilov, I.V. Sknar, Yu.E. Sknar, L.M. Pavlenko

The kinetics of сodeposition of nickel and iron in an electrolyte based on a deep eutectic solvent (ethaline) was studied by voltammetry method. It was established that the partial voltammograms of iron ions reduction during alloy electrodeposition correspond to the region of electrode potentials, which is more than 100 mV positive in comparison with the electrodeposition potentials of pure iron. It was shown that the acceleration of iron ion electroreduction is associated with the gain in energy due to the alloy formation and a decrease in the overvoltage of iron electrodeposition during alloying. The change in the kinetics of iron electrodeposition can be explained by both a change in the mechanism of its electrodeposition in conjunction with nickel and a change in the state of the electrode surface in the potential region of the alloy formation. Comparison between the ratio of the content of the alloy components in the metal and the corresponding ions in the electrolyte showed that nickel and iron electrodeposit into the alloy in quantities that are proportional to their content in the electrolyte. Thus, electrodeposition of nickel-iron alloy from ethaline with a water content of up to 3% occurs by the so-called normal mechanism.

25-31

Authors: A.I. Zahrai, Z.I. Borovets', I.V. Lutsyuk, Yа.M. Novitskyi

The method of mechanical activation of hydrated lime in a vibrating activator of bunker type was offered in this work. The influence of design features and angle of fixing of vibrating blades on the speed and degree of dispersion of hydrated lime was investigated by measuring the change in the logarithmic decrement of mass attenuation during vibro-activation. The effect of the duration of the vibro-activation process on the dispersion in the system "hydrated lime–water" was studied. The efficiency of lime dispersion was shown in the case of mounting the blades at the angle of 860 for 40–60 minutes. Comparative studies of the strength of cement stone showed that the addition of vibro-activated hydrated lime in an amount of 2 wt.% leads to an increase in the strength of lime-cement compositions.

40-44

Authors: D.Zh. Kut, M.M. Kut, M.Yu. Onysko, V.G. Lendel

The paper presents the results of the study of the process of electrophilic intramolecular cyclization of 3-methyl(phenyl)-2-(prop-2-yn-1-ylthio)-7-(trifluoromethyl)quinazolin-4(3H)-ones by tellurium tetrahalides. 3-Methyl(phenyl)-2-(prop-2-yn-1-ylthio)-7-(trifluoromethyl)quinazolin-4(3H)-ones were prepared by the alkylation of the corresponding thions with propargyl bromide in an alkaline alcohol medium. It is found that the interaction of propargyl thioethers of 3-substituted 2-thioxo-7-(trifluoromethyl)-2,3-dihydroquinazolin-4(1H)-ones with tellurium tetrahalides, which were obtained in situ from tellurium dioxide and six equivalents of corresponding concentrated hydrohalic acid, leads to the formation of halides of angular 4-methyl(phenyl)-5-oxo-1-((trihalotellanyl)methylidene)-8-(trifluoromethyl)-1,2,4,5-tetrahydrothiazolo[3,2-a]quinazolin-10-iums. The most optimal conditions for the tellurium-induced electrophilic heterocyclization of propargyl thioethers with tellurium terahalides are the use of glacial acetic acid as a solvent and stirring of the reaction mixture at room temperature for 24 hours. It is found that the electrophilic cyclization of 3-methyl(phenyl)-2-(prop-2-yn-1-ylthio)-7-(trifluoromethyl)quinazolin-4(3H)-ones by tellurium tetrahalides occurs stereoselectively with the formation of one configurational isomer. The influence of the nature of halogen in the electrophilic reagent and the substituent in position 3 of quinazoline is examined and it is found that these factors do not affect the regioselectivity of the electrophilic intramolecular cyclization process. As a result of the conducted study, potentially biologically active salts of tellurofunctionalized thiazolinoquinazolines of angular structure were received.

51-56

Authors: S.V. Pysarenko, V.Yu. Chernenko, O.E. Chygyrynets, O.M. Kaminskiy, M.O. Myronyak

X-ray spectral studies of the chemical composition of Irshansk ilmenite concentrates showed that it is leukoxenized mineral with a high (up to 79%) content of titanium oxide and inclusions of pseudorutile. The process of alkaline leaching of Ti4+ from ilmenite is investigated in the work. The study of the temperature effect on the reaction of ilmenite with potassium hydroxide at atmospheric pressure revealed that a temperature of 453 K is sufficient to obtain potassium titanate. A further increase in temperature does not provide a significant increase in the yield of water-soluble titanium. It is found that the optimal and sufficient ratio between ilmenite and potassium hydroxide is 1:2. An increase in the amount of potassium hydroxide in the reaction mixture is unsuitable, since it reduces the yield of soluble titanium and the final product will have a high alkalinity due to the presence of alkali which did not react. The main process of leaching with the formation of solid melt is completed in the first 30 minutes of the process. Infrared spectroscopy and X-ray diffraction showed that potassium titanate (K2TiO3) is formed under the studied conditions of alkaline leaching of ilmenite.

65-70

Authors: Y.M. Pushkarev, S.V. Saitarly

The effect of shungite on the structural and viscous-flow properties of compositions based on oligobutadiene was studied. The strength of coagulation structures of ebonite compositions filled with shungite was determined. The critical filling concentration was established and it is 40 wt.% of shungite per 100 wt.% of oligobutadiene. It was shown that increasing the temperature from 200C to 800C leads to a significant reduction in the shear stress required to destroy the structure of the composition. Temperature and shear rate independently affect the structured composition. Thus, it was shown that shungite powder can be used as a filler in liquid ebonite compositions based on oligobutadiene.

79-86

Authors: Ashwini Swaminathan, Ranjithkumar Ravi, Sakunthala Ayyasamy, Vidhya Bhojan, Rajesh Swaminathan, Raju Nandhakumar

The PVA–NH4SCN polymer membranes were prepared by simple solution casting technique by passing ultrasound waves during the preparation. The polymer membranes were subjected to X-ray diffraction analysis and scanning electron microscopy. The X-ray diffraction pattern confirmed the incorporation of a salt into the polymer matrix. The scanning electron microscopy images showed the morphological changes of the polymer membrane. The polymer electrolyte (designated as UPVA20) incorporated with the 20 wt.% of the salt had the highest electrical conductivity in the order of 10–4 S cm–1. It was concluded from the dielectric, tangent and modulus spectra that the UPVA20 membrane was good at its properties. Thus, electric double layer capacitor was constructed with UPVA20 membrane as the separator. The capacitance value of the electric double layer capacitor determined from cyclic voltammetry was found to be 1652 mF g–1. The ultrasound assisted preparation of polymer membranes were good at performance when compared with the polymer membranes of ultrasound unassisted preparation. Among all the polymer electrolytes, UPVA20 polymer membrane had high conductivity, potential stability and capacitance.

96-101

Authors: O.I. Chernetsov, O.V. Kobziev, V.V. Kazakov, V.G. Sozontov, O.V. Suvorin

The effect of nitrogen (III) oxide on the process of dinitrogen tetroxide separation in a dephlegmator during preparation of a "crude mixture" (HNO3–N2O4–N2O3–NO2–NO–H2O) in the production of concentrated nitric acid by direct synthesis was studied in this work. The dependence of crystallization onset on the composition of the N2O4–N2O3 mixture and temperature was determined. The refrigerant capable of maintaining the optimal temperature of the N2O4 extraction was suggested. The absence of nitrogen (III) oxide and nitrogen (I) oxide in the autoclave acid was confirmed.

21-29

Authors: Ya.S. Borodkin, E.B. Rusanov, Yu.G. Shermolovich

The work is devoted to the methods of synthesis of bis(polyfluoroalkenyl)sulfones and bis(polyfluoromethoxyalkenyl)sulfones as well as to the study of their reactions with diazomethane, resulting in the formation of N-methylated bis(pyrazolyl)sulfones isomers. Methods for the preparation of bis(polyfluoromethoxyalkenyl)sulfones not described previously in the literature have been developed by the addition of triethylamine and trimethylchlorosilane to a solution of the respective bis(polyfluoroalkyl)sulfones and methanol in diethyl ether in an argon atmosphere. A new method for the preparation of a previously unknown bis(3,3-difluoro-2,2-dimethoxypropyl)sulfone was suggested. The reaction occurs at room temperature in methanol in the presence of lithium hydroxide monohydrate. It was found that different regioisomeric bis(polyfluoroalkylpyrazolyl)sulfones are formed when using different methoxy derivatives of bis(polyfluoroalkenyl)sulfones in reaction with diazomethane, depending on the length of the polyfluoroalkyl moiety. These experimental data suggest that the attack of the double bond of methoxy-derived bis(polyfluoroalkenyl)sulfones by a molecule of diazomethane is influenced not only by the presence of an alkoxyl group, but also by the length of the polyfluoroalkyl substituent. The obtained bis(pyrazolyl)sulfones were investigated for the possibility of their use as ligands in the chemistry of metal complexes. It was shown that 5,5'-sulfonylbis[4-(difluoromethyl)-1-methyl-1H-pyrazole] forms a polymeric metal complex with silver nitrate. The results of X-ray structural analysis of the prepared coordination compound are presented. According to these results, the silver atom coordinates with two nitrogen atoms of pyrazole cycles of different molecules in the crystal of the obtained metal-complex compound, forming a supramolecular structure. In our opinion, an important role in this arrangement is played by the nitrate group that is coordinated with two silver atoms. As a result, we observed a supramolecular structure in the crystal that had a spiral structure with some free space in the middle. The paper also presents the results of spectral and X-ray diffraction analysis of a new regioisomeric compound of bis(3-hexafluoropropyl-1-methylpyrazolyl)sulfone.

37-42

Authors: A. Galstyan, A. Bushuyev, A. Krasilnikova, M. Zhurba

The kinetics and mechanism of oxidation of 4-bromoacetophenone by ozone in acetic acid solution have been studied. It was shown that 77% of the starting material is oxidized by the benzene ring; 8% of 4-bromobenzoic acid and small amounts of carbon (IV) oxide were identified among the side chain ozonation products. The main reaction products are aliphatic peroxide compounds, which have in their structure one hydroperoxide group. Manganese (II) acetate was shown to be the most effective catalyst for the side chain reaction of 4-bromoacetophenone in acetic acid. High selectivity for the side chain is achieved only at sufficiently high concentrations of catalyst ([Mn(OAc)2]0:[ArH]0=1:4). The main product of the catalytic oxidation of 4-bromoacetophenone is 4-bromobenzoic acid with a yield of 82.5%. The found dependences of the rate of oxidation of 4-bromoacetophenone by ozone on the concentration of reactants are described by the kinetic equation of the third order, the reaction rate has the first order with respect to each reagent. It was found that the decisive role in the selective oxidation of 4-bromoacetophenone is played by two-stage oxidation, in which ozone predominantly reacts with the reduced form of manganese, and the introduction of the substrate into side chain oxidation is carried out by the reaction with the oxidized form of metal. According to the research results, the mechanism of catalytic ozonation of 4-bromoacetophenone in acetic acid has been proposed, which involves ion-radical non-chain oxidation of the substrate.

50-58

Authors: F.I. Danilov, Y.D. Rublova, V.S. Protsenko

Adsorption of the components of deep eutectic solvent ethaline (ethylene glycol and choline chloride) on mercury electrode is investigated by electrocapillary measurements. It is determined that choline cations are mainly adsorbed on the negatively charged surface of mercury, while chloride anions are mainly adsorbed on the positively charged surface. The corresponding values of free energies of adsorption and interactions of adsorbate and solvent with metal are calculated and analyzed. An anomalous increase in both the apparent value of the adsorption at limiting coverage and the free energy of the interaction of the choline cation with mercury is observed in the transition from aqueous to ethylene glycol solutions, which is explained by the formation of complexes in a surface layer that exist in deep eutectic solvents and are capable of adsorbing on the electrode surface. The free energy of interaction with the mercury surface is higher than the energy of squeezing out from the volume of the solution onto its surface, which indicates the specific interaction of the adsorbate with mercury. A marked decrease in interfacial tension on both branches of the electrocapillary curve is observed when water is added to ethaline.

68-76

Authors: V. Knysh, O. Shmychkova, T. Luk'yanenko, L. Dmitrikova, A. Velichenko

The effect of potassium perfluorobutanesulfonate on the kinetic features of electrodeposition of lead dioxide from methanesulfonate electrolytes has been investigated. The introduction of C4F9SO3K into the lead dioxide deposition electrolyte leads to insignificant inhibition of the Pb2+ electrooxidation process, while the mechanism of the process does not change. A composite coating is formed upon deposition of coatings from electrolytes containing surfactants. The surface of a composite material consists of a mixture of clearly expressed large crystalline blocks with sharp angles and small crystals. Energy dispersive X-ray analysis revealed the satisfactory distribution of modifying elements in the entire sample bulk, and not only on the coating surface. It was shown that the electrocatalytic activity of lead dioxide–perfluorobuthanesulfonate composite differs from the undoped sample. The oxygen evolution reaction slightly decelerates on a PbO2–C4F9SO3K composite. The Tafel slopes in 1 M HClO4 calculated from these curves plotted in semilogarithmic coordinates are 136 and 145 mV dec–1 for undoped sample and lead dioxide-surfactant composite, respectively. The reaction of electrochemical oxidation of p-chlorophenol is characterized by the pseudo-first order kinetics with respect to the initial compound. The use of doped C4F9SO3K lead dioxide as an anode leads to the inhibition of the process of oxygen evolution and an almost one and a half higher rate of electrochemical conversion of 4-chlorophenol to aliphatic compounds.

84-89

Authors: O.V. Pavlyuk, Yu.I. Slyvka, N.T. Pokhodylo, M.G. Mys'kiv

By means of the alternating current electrochemical technique and starting from copper wire electrodes in propanol solution of corresponding ligand and copper(II) nitrate, novel copper(I) -complex [Cu2(C12H14SN4)2(NO3)2] (1) has been obtained and X-ray structurally investigated: sp. gr. , a=7.352(3) Å, b=8.269(3) Å, c=12.723(4) Å, =82.08(3)0, =82.74(3)0, =88.37(3)0, V=759.9(5) Å3, Z=2, dcalc=1.625 g cm–3, (CuK)=3.502 mm–1, max=67.960, 4119 measured reflections, 1248 used reflections, 201 refined parameters, R(F2)=0.0915, S=0.95. The trigonal-pyramidal copper(I) coordination environment consists of nitrogen atom and allylic group of ligand, and of two oxygen atoms from crystallographically distinct nitrate anions. Due to a bridging function of oxygen atoms of nitrate anions, two metal-containing polyhedra are connected into {Cu2L2(NO3)2} topological units which are additionally stabilized by noncovalent interaction CuO(2). Comparatively weak hydrogen bonds C–HO exist in the crystal structure of [Cu2(C12H14SN4)2(NO3)2] (1).

97-104

Authors: N.V. Polish, M.V. Nesterkina, M.S. Protunkevych, A.I. Karkhut, N.G. Marintsova, S.V. Polovkovych, I.A. Kravchenko, O.Y. Voskoboinik, S.I. Kovalenko, O.V. Karpenko

Novel naphthoquinone derivatives bearing 1,2,4-triazine- (4a–b) and 1,2,4-triazole (5a–e) pharmacophores have been synthesized; their structure was confirmed by electrospray ionization mass spectrometry, 1H NMR, 13C NMR, IR spectroscopies and elemental analysis. The obtained heterocyclic compounds were estimated for their anticonvulsant activity on models of chemical- and electrical-induced seizures in pentylenetetrazole (PTZ) and maximal electroshock (MES) tests, respectively. Forced swimming test was used to evaluate the antidepressant effect of the naphthoquinone derivatives under study. Compounds 4a–b and 5a–e (100 mg kg–1) demonstrated anticonvulsant action comparable with valproic acid in PTZ-test and prevented the death of 100% of mice in MES model at 3 h and 24 h after oral administration. Moreover, these derivatives showed prolonged antidepressant-like properties, significantly reducing the duration of immobility time in comparison with the reference drug amitriptyline.

111-117

Authors: A.B. Surovtsev, I.A. Mandzyuk, D.O. Chervakov, M.F. Seferova, O.V. Chervakov

We present the results of creation of paste-like fuel compositions with a high degree of filling (up to 90 wt.%) and investigation of their rheological properties. The developed composition contained the following components: a polymer matrix (type SNBR-N butadiene rubber) and a mixture of inorganic fillers (preliminarily surface-modified highly disperse potassium chloride, that was microencapsulated by using oligomeric products of polyehtyleneterepthalate glycerolize, and highly dispersed aluminum powder. A surface-active compound (oligomeric polioxypropylene glycol) and plasticizers of different natures were used as additional components, which were introduced in order to increase the degree of filling of the resulting paste-like compositions while maintaining a low level of their viscosity. The dynamic viscosity of the compositions was evaluated in the range of the shear stresses of 1 to 30 kPa and the temperatures of 293 to 323 K by using a rotary viscometer (cone–plane system). The viscosity of the composition which is a mixture of saturated and unsaturated methyl ester fatty acids at the maximum degree of filling (90 wt.%) was at the level of viscosity of the individual binder.

11-20

Authors: V.S. Gevod, A.S. Chernova

This work was aimed creating a simple and reliable submersed biofilter for the decentralized treatment of nitrate-contaminated water. Denitrification of water was studied by the method of displacement (piston) bio-filtration in specially designed devices intended for home application. At certain sizes of grains of bio-filtration bed and filtration flow directions in it, the change in operating mode of denitrifying biofilter from direct flow to displacement mode offers the following advantages. There is no need to maintain a continuous and slow flow of water through the biofilter. The consumers have the opportunity to feed big portions of water into the bio-filter in one gulp (pulse) and nevertheless get the same quantity of denitrified water. The design of created biofilters is simple. Assembling these bio-filters implies the use of materials with a minimum carbon footprint.

27-34

Authors: G. Gece

There is no doubt that the value and importance of using computational methods in corrosion science are becoming gradually recognized. Drilling deeper into the thought that certain molecular electronic descriptors such as ionization potential, electron affinity, HOMO–LUMO gap and dipole moment matter, because they present a unique solution to comprehend the inhibition properties of corrosion inhibitors, leads us to a further quandary. The reliability of such parameters is the subject of acrimonious debate, and thus, the present study is an extension of this attempt to contemplate earlier experimental results reported for some Schiff and Mannich bases as corrosion inhibitors for steel in neutral aqueous solutions by using density functional theory calculations. Due to the sources of uncertainties like the structure of the molecular model, the description of environmental efforts and errors related to the nature of quantum chemical methods, it was inferred that no coherent picture could be emerged about the corrosion inhibition properties of the studied compounds through calculated descriptors.

41-49

Authors: W.S.B. Dwandaru, E.K. Sari, W. Widyawidura, D.S. Khaerudini, E. Pratidhina, M. Agustin, L. Purnamasari, W. Silfiyani, T.A. Yongga

We report the synthesis of carbon nanodots (Cdots) from watermelon peel waste. The Cdots obtained were characterized using ultraviolet-visible, photoluminescence, Fourier-transform infrared spectroscopies, and transmission electron microscopy. The Cdots exhibited green luminescence. The average diameter of the Cdots was 4 nm and the C=C functional groups were dominant. The Cdots were then utilized as CO2 absorbent in biogas. The result showed that the concentration of CO2 was reduced by up to 40% based on the gas chromatography test. The higher the Cdots concentration, the higher is the amount of CO2 that can be reduced in the biogas. Based on the heat performance test, higher concentration of Cdots produced higher heat energy of the biogas.

58-65

Authors: O.S. Ivashchuk, V.M. Atamanyuk, Z.Ya. Gnativ, R.A. Chyzhovych, R.R. Zherebetskyi

The article describes the results of experimental studies on kinetics of the filtration drying of corn distillery stillage, which has previously proven its effectiveness in drying other crops and various dispersed materials. The experimental data are presented in the form of graphical plots describing the change of material moisture over time depending on the temperature of the drying agent (60, 70, 80 and 900С) and the layer height (40, 80, 120 and 160 mm). The obtained results are analyzed and the changes that occur on the filtration drying curves depending on the change in the material layer height and drying agent temperature are described. It is shown that the filtration drying time of alcohol distillery stillage increases with increasing the material layer height. It is determined that the drying potential remains constant at the same parameters of the drying agent. It is shown that the rate of moisture removal during the filtration drying does not depend on the material layer height. It is found that the average residual moisture of corn alcohol distillery stillage is 3.140.06 wt.%; this value satisfies industrial needs for an increase in its shelf life and the possibility of long-term storage and transportation.

73-77

Authors: A.V. Kovtun, S.A. Varenichenko, E.V. Zaliznaya, A.V. Mazepa, O.K. Farat, V.I. Markov

We have proposed a method for the synthesis of previously unknown bromo xanthenes using the reagent PBr3/DMF as a rearrangement initiator. Bromo derivatives of xanthenes in the form of organic perchlorates were prepared by reacting the corresponding benzo(naphtho)dioxin-4(1)-ones with a three-fold excess of Vilsmeier-Haack PBr3/DMF reagent at 1100C for 2 hours, followed by the addition of sodium perchlorate. The conditions for the synthesis of formyl derivatives of xanthenes under conditions of acid hydrolysis were selected. The structure of the compounds was confirmed by 1H and 13C NMR spectral data and mass spectrometry. Preliminary studies showed that it is possible to selectively replace the dimethylamino group and the bromine atom with various nucleophiles in bromo derivatives of xanthenes, which opens up wide possibilities for the synthesis of low-molecular building blocks and dyes.

84-88

Authors: V.M. Mykhalichko, L.O. Fedyna, A.O. Fedorchuk, M.F. Fedyna

Crystal structure of the ternary compound ErPtSi2 (diffractometer HZG-4a, CuK-radiation, structure type YIrGe2, Pearson symbol oI32, space group Immm, a=4.19395(6) Å, b=8.41465(13) Å, c=15.85404(19) Å, RB=0.0639, Rp=0.0424, and 2=1.11) was studied by X-ray powder diffraction method. Intermetallide ErPtSi2 is the first representative of YIrGe2 structure type in R–Pt–Si systems. Crystal structures of ternary compounds in the system Er–Pt–Si were analyzed and the structural relationships between them were established according to the systematics of the nearest coordination environment around the less electronegative Er atoms. Compounds, found in the system, were divided into two main types based on the nearest coordination environment, namely on the derivatives of hexagonal and pentagonal prisms with different amounts of additional atoms. These polyhedra exist both alone and in the combination with each other and with cubooctahedra in the structures of the different ternary silicides of erbium. Such a relatively small coordination environment of rare-earth metal atoms can be explained by the structural peculiarities of the ErPt3 binary compound. The coordination polyhedra of the smallest atoms are trigonal prisms with different amounts of additional atoms or cubooctahedra.

96-105

Authors: V.G. Nefedov, V.V. Matveev

We analyzed the possibilities of the use of the cluster model of water to assess its viscosity. The Nemethy-Scheraga model was used in our study. In a simplified version, this model implies the presence of water cluster that are linked by hydrogen bonds as well as individual molecules (monomolecules) interacting only by van der Waals forces. The paper gives an estimation of average cluster size. Based on the experimental temperature dependences of viscosity and density, the content of monomolecules in water was approximately determined. In the first case, the ratio of the viscosity of water to monomolecules was estimated from the inverse Arrhenius temperature dependence of viscosity by considering experimental activation energy ~18.6 kJ mol–1 (0÷300C) and energy of dispersion interactions ~7.4 kJ mol–1. Then, the volumetric content of monomolecules was estimated by using the inverse Betchelor's formula, which relates the viscosity of the suspension (clusters) and dispersion medium (monomolecules) to their ratio. On the other hand, a similar estimation was performed based on the density of water, clusters that were considered similar to ice floes, and the estimated density of monomolecules. Both estimates showed that the volumetric content of water not bound into clusters does not exceed 9%. It was concluded that the structure of water most likely corresponds to the clathrate model, according to which some of the H2O molecules move into the middle of ice-like clusters, and vacancies are stabilized by H3O+–OH– pairs.

112-117

Authors: N.Yu. Strutynska, M.S. Slobodyanik, Y.O. Titov, I.A. Kraievska, L.O. Кhmarska

The features of phase formation during wet coprecipitation from aqueous system Сa2+–NO3––Х (Х – NaH2PO4, Na2HPO4, Na3PO4) at the molar ratio Са2+/РО43–=1.6 and room temperature have been investigated. It was found formation of whitlockite-related calcium phosphates (trigonal system, space group R-3c). The results of elemental analysis indicated the chemical modification of calcium phosphates by sodium cations (samples contained 0.3–0.6 wt.% Na+). According to the resulta of thermogravimetry, the synthesized samples contained up to 6 wt.% of sorption water. Heating of samples to the temperature of 6000C is accompanied by water removal and an increase in particle size from 20–50 nm to 500 nm. It was shown that the use of sodium nitrate as a source of sodium cations in the formation of sodium-containing calcium phosphates allows obtaining compositions of whitlockite- and apatite-related phases. The mass ratio of phases can be adjusted by changing the content of sodium cations in the initial solution. The synthesized samples were characterized by X-ray powder diffraction, thermogravimetry, scanning electron microscopy and FTIR spectroscopy methods. Optimized conditions for preparation of whitlockite-related sodium-containing calcium phosphates as well as composites based on them with apatite-related phase can be further used in the development of materials with the required resorption rate for orthopedics.

126-133

Authors: М.О. Chaban, L.M. Rozhdestvenska, О.V. Palchik, L.M. Ponomarova, Y.S. Dzyazko

A method for obtaining nanocomposite sorbents, which are selective towards Li+ ions, has been proposed. The samples were based on adsorptive-active anatase, the selective component being lithium-manganese spinel LiMn2O4. This component was synthesized preliminarily, its nanoparticles were added to the sol of insoluble titanium hydroxocomplexes, and the nanocomposite was precipitated from this suspension and calcined at 5000C. A number of sorbents with different molar ratio of Ti:Mn were prepared via this procedure; they were investigated by means of chemical analysis, X-ray diffraction analysis, optical microscopy, transmission electron microscopy and scanning electron microscopy. The size of nanocrystallites was 20–30 nm. An increase in the spinel amount caused a decrease in the sorbent grain size; however, they the sorbent grains were mechanically durable due to TiO2 which was a binder. Adsorption of Li+ from the solution containing an excess of Na+ ions was studied. The optimal amount of LiMn2O4 (13%) was determined. The sample was obtained in the form of rather large grains (0.3 mm) and the selectivity coefficient Li+/Na+ was about 500. The sorbent was regenerated by a 1 M HNO3 solution without manganese leakage. After 10 cycles of sorption-desorption, the concentrate was obtained. This concentrate can be used for Li2CO3 precipitation.

142-150

Authors: O. Shmychkova, I. Borovik, D. Girenko, P. Davydenko, A. Velichenko

The synthesis of hypochlorous acid from low concentrated chloride-containing electrolytes has been studied on various oxide materials at the anode current density of 50 mA cm–2. Boron doped diamond, platinized titanium, metallic titanium doped with platinum and palladium and materials based on lead (IV) oxide modified with fluorine and surfactants turned out to be promising for the synthesis of hypochlorous acid by electrolysis. Whereas, given the stability of oxidant synthesis during cumulative electrolysis, titanium modified with platinum and palladium as well as pre-treated lead (IV) oxide containing surfactants (sodium laureth sulfate) was the best. One should additionally take into account the possibility of combined use of electrocatalysts for the synthesis of strong oxidants in the reverse current mode in flow systems, when the implementation of the gas cathode leads to the formation of hydrogen peroxide and hypochlorous acid is formed at the anode. In fact, only a metal electrocatalyst, such as titanium modified with platinum and palladium, can be a suitable material. The kinetics of hypochlorite conversion is primarily determined by the pH value of freshly prepared solutions, temperature and storage conditions. The presence of different organic and inorganic micro-impurities in the solution also affects the kinetics of the hypochlorite salt decomposition. The following micro-impurities show the most negative impact on the stability of sodium hypochlorite solutions: Co(II), Cu(II), Mg(II), Al(III), and K3[Fe(CN)6]; Ni(ІІ), Fe(III), and K4[Fe(CN)6] influence the stability to a lesser extent. The effect of chlorate on the inhibition of sodium hypochlorite activity as a disinfectant has been investigated. The presence of chlorate in the disinfectant solution involved results in the absence of bactericidal activity against S. aureus and P. aeuruginosa. The growth of pseudomonas colonies becomes more abundant with increasing chlorate content in the disinfectant.

32-41

Authors: V.L. Avramenko, G.M. Cherkashyna, L.P. Pidhorna

This work is devoted to the development and study of the processes of accelerated structuring of polymer composite materials in the field of high-frequency current (microwave field) which are used in the electronic and instrument-making industries, etc. The complex of properties and the features of structuring of epoxy, acrylic and epoxy acrylic polymer composite materials in the microwave field are investigated. In comparison with the traditional method of structuring and polymerization (convection heating), the structuring in the microwave field equally affects the properties of the studied polymer composite materials, regardless of the chemical nature of the oligomer. The action of the microwave field for all studied polymer composite materials causes an increase in the degree of conversion of binders and a decrease in the content of residual monomer (methyl methacrylate) in thermoplastic acrylic polymer composite materials. In addition, the microwave treatment provides the completeness of chemical and physicochemical processes of the formation of rational structure of polymer composite materials with stable properties. The conducted research allows recommending various regimes of the structuring of the studied polymer composite materials taking into account operating conditions. These regimes ensure the reduction of structuring duration and provide a high level of mechanical and operational properties.

50-56

Authors: L.R. Harutyunyan, R.S. Harutyunyan

The role of both dimeric and monomeric forms of acrylamide monomer in the process of polymerization in emulsions initiated by different type of initiators was discussed and the reasons for the reaction order with respect to monomer greater than unity were elucidated for acrylamide free radical polymerization in emulsions. The emulsion polymerization mechanism of acrylamide is discussed separately for the processes initiated by water-soluble initiator and oil-soluble initiator. The main difference in two cases is the distribution of acrylamide and initiator in aqueous and toluene phases. In the case of using water-soluble initiator, the initiator and acrylamide are in the same phase, whereas the molecules of the initiator and acrylamide are distributed between different phases in the case of using oil-soluble initiator. As a result, the participation of the dimers in the process of acrylamide emulsion polymerization is more efficient for the system where water-soluble initiator is used. For that system, it is suggested that both dimers and monomers of acrylamide participate in the propagation reaction at relatively low concentrations of acrylamide, which explains the value of the reaction order with respect to monomer greater than unity.

64-72

Authors: I.I. Gaidarzhy, L.A. Motnyak, B.V. Kunshenko

In order to synthesize procaine analogs containing one or two pentafluoroethoxy groups, a method for the synthesis of benzoic acids containing a pentafluoroethoxy group in the ortho-position of the benzene nucleus has been developed. An effective method for the synthesis of procaine structural analogues containing one or two pentafluoroethoxy groups has been proposed. It has been shown that the replacement of the amino group by the pentafluoroethoxy group in the procaine molecule leads to a significant increase in the local anesthetic activity of the obtained compounds. The most active compound was a structural analogue of procainamide containing two pentafluoroethoxy groups in positions 2 and 4. The formation of fluorine-containing analogues of procaine was confirmed by 1H, 19F and 13C NMR spectroscopy and mass spectrometry.

83-89

Authors: Yu.S. Hordieiev, E.V. Karasik, А.A. Amelina

This article shows the prospect of the system BaO–Al2O3–B2O3–SiO2 as the basis of vitreous and glass ceramic materials, which are widely used in rocket production for high-temperature protection of heat resistant alloys, in the power industry for sealing solid oxide fuel cells, and in the production of heat resistant glass ceramic materials. We examined the conditions of glass formation and properties of glasses with the following content of components (mol.%): BaO 30–70, B2O3 10–50, SiO2 20–60, and Al2O3 0–10. We established experimentally that the physical and chemical properties of glass, depending on its chemical composition, vary within the following limits: coefficient of linear thermal expansion of (71–122)10–7 К–1; glass transition temperature of 500–6500С; dilatometric softening point of 540–6700С; and density of 3.20–4.21 g cm–3. The volume resistivity of the studied glasses is within 1011–1013 Ohmcm at the temperature of 1500С. Generalization of the dependences of glass properties on their chemical composition was carried out with the use of the additive equations, for which the partial contributions of oxides to the values of the corresponding properties were determined by experimental and statistical methods. The established patterns of influence of components and conditions of glass formation on the physical and chemical characteristics of glasses allows implementing the process of designing of a wide range of glass compositions with the complex of specified properties in order to solve the tasks of their practical use.

100-106

Authors: Y.I. Koltsova, V.I. Ovcharenko

This study was aimed at producing a porous layered glass ceramic material with a decorative-protective coating via one-stage firing. Waste products were used as gas-forming agents to fabricate a glass ceramic material, which partially solves a problem of their utilization; available natural raw materials were also used as gas-forming agents. A decorative-protective coating was applied simultaneously with the formation of the main layers of the material. It consisted of glass cullet and various amounts of coloring oxide. Firing of the samples was carried out at the temperature of 7500С. The coating containing 99.9 wt.% of glass cullet and 0.1 wt.% of Cr2O3 with the thickness of 425 m and having a greenish color was stated to be the coating of the highest quality. As a result of the research, a three-layer porous glass ceramic material was obtained with a low coefficient of thermal conductivity (0.056 W m–1 K–1). The presence of a fourth front decorative-protective layer will allow using this material in construction as a heat-insulating and structural material without additional cladding.

113-120

Authors: V.К. Lukashov, Y.V. Кostiuchenko, V.I. Sereda

The article presents the results of the investigation of the process of concentrating solutions of low-volatile liquids in a flowing film under the conditions of evaporation in the cross-flow of neutral gas. The purpose of the study was to establish the features of solution composition change along the film length. The study was carried out using the developed mathematical model with experimental determination of model parameters: heat and mass transfer coefficients. It was found that at the beginning of the film, the change in the concentration of the solution has a character close to linear, and then the concentration sharply increases until the solvent evaporates completely. It was shown that this pattern of change in the composition of the solution is related to the distribution of the temperature of the solution along the length of the film. The intensity of the concentration process increases with decreasing initial flow rate of the solution and its initial concentration as well as with increasing initial temperature of the solution, initial temperature of the gas and temperature of the surface of the wall along which the film flows. The concentration intensity decreases with an increase in the velocity of the gas entering the space above the film. Comparison of the calculation results concerning aqueous glycerol solution with the experimental data showed their good agreement. The data obtained in the article allow calculating the height of the film concentrator nozzle at which a given concentration of the solution is provided.

128-136

Authors: K.M. Sukhyy, E.A. Belyanovskaya, A.N. Nosova, M.K. Sukhyy, V.P. Kryshen, Y. Huang, Yu. Kocherhin, T. Hryhorenko

In order to improve the adhesive and physical-mechanical properties of epoxy-thiocol compositions cured without heat treatment, we propose to carry out the reaction of interaction between thiokol mercaptan groups and oxirane cycles of epoxy resin at an elevated temperature before introducing a curing agent, and then use the product of this thioetherification reaction for curing at room temperature. The temperature range of the thioetherification reaction (90–1800С) was determined by the method of differential scanning calorimetry. The optimal temperature (1600С) and duration of the preliminary thioetherification reaction (2 hours) were determined, which ensure the maximum level of adhesive strength and physical-mechanical properties. It was shown that composite materials based on the products of the thioetherification reaction significantly outperform analogs based on mechanical mixtures of epoxy resin and thiokol in terms of cohesive and adhesive strength, deformation capacity, fracture work and specific impact strength. The impact resistance and shear strength of adhesive joints are especially significantly increased during the curing of the compositions without external heat supply.

145-149

Authors: D.O. Chervakov, O.S. Sverdlikovska, O.V. Chervakov

To improve the physical-mechanical and thermophysical properties of polypropylene-based thermoplastic composite materials, we performed modification of a polymer matrix by reactive extrusion of polypropylene in the presence of benzoyl peroxide and polysiloxane polyols. Modified polypropylene was compounded with basalt, carbon, and para-aramide reinforcing fillers in a screw-disc extruder. It was established that the reinforcement of modified polypropylene by basalt fibers ensured a 110% increase in tensile strength. The reinforcement of modified polypropylene by carbon fibers allowed fabricating thermoplastic composite materials with tensile strength increased by 14%. The maximum reinforcing effect was observed by using para-aramide fibers as reinforcing fibers for modified polypropylene with tensile strength increased by 30% as compared with initial polypropylene. It was determined that the obtained thermoplastic composite materials based on modified polypropylene can be processed into products by the most productive methods (extrusion and injection molding). The developed materials exhibited improved thermal stability. The proposed ways of modification methods provide substantial improvement in physical-mechanical and thermophysical properties of modified polypropylene-based thermoplastic composite materials as compared with initial polypropylene. In addition, they ensure a significant increase in service properties of the products prepared from thermoplastic composite materials based on modified polypropylene.