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

16-30

Authors: Yu.V. Sukhatskiy, Z.O. Znak, O.I. Zin

The review provides a systematic understanding of the mechanism of the sonochemical degradation of phenol. It was shown that the main contribution to the sonochemical degradation of phenol, a hydrophilic non-volatile wastewater component, is related to hydroxylation on the boundary of the "cavitation bubble–water contaminant solution". Depending on the method of generating hydroxyl radicals, all wastewater treatment methods for phenol removal based on advanced oxidation processes are classified into the following categories: chemical (acoustic and hydrodynamic cavitation, use of oxidants, Fenton process, and Fenton-like processes), photochemical (photolysis and photocatalysis), electrochemical and combined techniques. The essence of these methods is revealed and their main advantages and disadvantages are reviewed. It is shown that the efficiency of combined methods of phenol degradation that are based on the use of cavitation (acoustic or hydrodynamic) depends on the power of ultrasonic emitters, the frequency of ultrasonic vibrations, the magnitude of the pressure at the inlet of the hydrodynamic cavitator, physicochemical properties of media (temperature and pH), initial phenol concentration in aqueous medium, the design features of the cavitation generators, the presence of water-soluble gases or solid particles that exhibit catalytic properties, and the consumption of oxidizing reagents. Literature data showed that the most cost-effective method involving the use of ultrasonic cavitation is a combination "ultrasonic cavitation+photolysis+ozonation". The choice of a particular method for the degradation of phenol is determined by its content in wastewaters and their volume, the required degree of degradation, the duration of the purification process (the rate of degradation of the phenol), and economic indicators.

38-42

Authors: A.G. Galstyan, K.S. Skorokhod, T.M. Galstyan

The kinetics of the catalytic cycle reactions in the oxidation of ethylbenzene by ozone in acetic acid at temperatures of 288–303 K were investigated, which allowed us to formulate the general characteristics of the catalytic oxidation of ethylbenzene by ozone, explain the role of the catalyst in the system and develop a chemical scheme of oxidation. Manganese (II) acetate is shown to be an effective catalyst for the side chain reaction of ethylbenzene ozonation. High side-chain selectivity is achieved only at sufficiently high concentrations of catalyst ([Mn (OAc)2]0:[ArH]0=0.1). The main oxidation products of ethylbenzene are acetophenone (76.5%) and -phenylethanolacetate (11.2%), which are converted into benzoic acid at elevated temperatures. It has been found that two-stage oxidation plays a decisive role in the selective oxidation of ethylbenzene and its oxygen-containing derivatives in which the ozone reacts predominantly with the reduced form of manganese, and the introduction of the substrate into the oxidation by the lateral chain is accomplished. Ozone should be continuously added to the system since its absence leads to metal recovery and a further cease of the process. The degree of reduction of manganese, which slows down the reaction, depends on the temperature: the higher the temperature, the greater is the degree of recovery of the catalyst. The reaction is inhibited by the appearance of Mn (II) in the system, which is explained by the formation of the complex of a substrate with Mn (IV) and Mn (III) at the first stage. The maximum selectivity with respect to acetophenone is reached at 288 K. With increasing the temperature, the rate of accumulation and selectivity gradually decrease. A simultaneous decrease in these parameters is explained by a slightly higher value of the activation energy of the reaction Mn (IV) with acetophenone than the value of the activation energy of its reaction with ethylbenzene (37.7 and 32.8 kJ mol–1, respectively).

55-59

Authors: I.V. Efimova, O.V. Smirnovа, I.A. Opeida, L.N. Vakhitova

The initiated oxidation of cumene was studied in an aprotic medium in the presence of ascorbic acid and anion radical of oxygen. Superoxide anion was prepared by the reaction of KO2 complexation with 18-crown-6 ether. The kinetics of the oxidation process was monitored by the gas volumetric measurements by determining the volume of absorbed oxygen at a constant partial pressure of oxygen and a temperature of 348 K. The study was conducted at a constant concentration of the complex КО218-crown-6 in the system and at varying the concentration of ascorbic acid. The kinetic absorption curves of oxygen absorption were obtained for the test systems with different inhibitors. It was shown that the presence of ascorbic acid and superoxide anion ensures an synergistic effect of oxidation inhibition. To characterize the joint action of ascorbic acid and anion radical of oxygen on the cumene oxidation process, a parameter characterizing the synergistic inhibition efficiency was introduced and calculated. An optimum ratio of ascorbic acid to superoxide anion was determined to provide a maximally efficient synergistic action of antioxidants in the process of inhibition of chain-radical oxidation of cumene in an aprotic medium. Conclusion was made regarding possible ways of neutralizing the negative effects caused by the presence of superoxide anion.

66-71

Authors: A. Kityk, V. Protsenko, F. Danilov, V. Pavlik, M. Hnatko

Electropolishing of Al–Mg alloy (5 wt.% of Mg) in a deep eutectic solvent ethaline (a eutectic mixture of choline chloride and ethylene glycol) was investigated. Scanning electron microscopy and atomic-force microscopy revealed that the electrochemical surface treatment in ethaline provided a significant improvement of the surface characteristics of Al–Mg alloy. The amount of surface oxygen decreased after electropolishing of aluminium–magnesium alloy in ethaline as compared with the untreated surface. A removal of aluminium oxide film took place during electropolishing and no anodization was observed. The potentiostatic electropolishing of Al–Mg alloy in ethaline at the potential of +6 V (against Ag pseudo-reference electrode) and the temperature of 25C allowed reducing the surfaces roughness coefficient. The study of corrosion behavior of Al–Mg alloy in 10 wt.% NaCl solution before and after electropolishing in ethaline was performed by using liner polarization resistance technique. It was established that the electrochemical polishing in ethaline caused an improvement in corrosion resistance of Al–Mg alloy. Thus, the deep eutectic solvent ethaline can be used as an environmentally friendly, resource-saving and inexpensive alternative to common hazardous acidic electrolytes for electropolishing of Al-based alloys.

80-87

Authors: V.V. Kochubei, S.G. Yaholnyk, S.V. Kniaz, L.Y. Parashchuk, M.S. Malovanyy

The paper reports the effects of the activation conditions on the adsorption capacity of Transcarpathian clinoptilolite. Naturally occurring clinoptilolite underwent chemical activation by 5% and 25% aqueous solutions of H2SO4 at the solid-liquid ratio of 1:10. Thermal activation was performed by the heating of chemically activated clinoptilolite at the temperature of 300C. Thermal analysis showed that the sample activated by 25% H2SO4 solutions demonstrated the highest adsorption capacity with respect to water vapor and the highest content of hydroxyl groups that were lost at the temperatures greater than 500С. The data obtained can be explained by partial dealumination of zeolite, which is accompanied by an increase in its internal crystalline space and the emergence of additional adsorption active centers. The destruction of Si–O–Al bonds, which gave rise to the Brønsted adsorption active centers, was confirmed by the results of IR spectroscopic and X-ray phase analyses. The IR spectrum of the sample activated by 25% H2SO4 solution exhibited a drastic shift of band associated with tetrahedral stretching vibrations to the region of higher frequencies. A significant reduction of reflections in X-ray diffraction pattern of the sample treated by 25% H2SO4 solution appeared in the region 2=32–34 (CoK radiation). This indicated steric strains of crystalline lattice due to decationization and dealumination processes. A comparative analysis of both naturally occurring clinoptilolite and modified by 25% H2SO4 solution was performed to characterize the capacity to adsorb direct dye molecules from their aqueous solutions. An increase in the adsorption capacity of activated clinoptilolite was ascribed to the emergence of additional Brønsted acid centers that became available to dye molecules during the activation of clinoptilolite. The constants of the Langmuir monomolecular adsorption isotherm equation were determined.

96-105

Authors: A.V. Mishchenko, E.A. Venger, D.S. Kachuk

The paper summarizes the results of the research into the use of polyethoxylates modified with isocyanates and fatty alcohol in the processes of textile finishing. It was showed that they can be used both as thickeners of pigment compositions based on polyurethane binders for the printing of textile materials and as components of compositions for printing with disperse dyes. The research also revealed the features of rheological behavior of thickening based on modified polyethoxylates and the ways of improvement of their pseudoplastic properties. It was found that modified polyethoxylates simultaneously act as protective colloids, which significantly increases their shelf life as compared with typical pigment compositions. The application of modified polyethoxylates allows reducing the number of components in the textile finishing compositions. First, the thickeners based on modified polyethoxylates act as intensifiers in the process of fixation on synthetic fibers during printing by disperse dyes, which allows decreasing the dye content in the composition for printing and thus reducing its consumption maintaining color intensity. Second, the efficiency of modified polyethoxylates as intensifiers of moisture adsorption allows reducing or even completely eliminating the content of hydrotropic substances (in particular, urea) that are present in typical compositions. Third, the use of modified polyethoxylates in pigment compositions results in complete removal of special softeners from compositions, since polyethoxylates act as effective softeners of printed fabrics.

115-120

Authors: A.A. Ovcharenko, O.V. Velichko, A.A. Golichenko, A.V. Shtemenko

Hydrolysis of a dirhenium(III) complex compound with -alanine ligands was investigated by UV-vis, IR- and NMR-spectroscopy methods. Electronic absorption spectra (EAS) of cis-[Re2(-Ala)2(H2O)2Cl4]Cl2 in physiological solution over time showed a gradual decrease in the absorbance of a characteristic absorption maximum at 15630 cm–1 during 3 days. Changing the pH of the solution and studying the EAS, we have concluded that the Re26+ cluster fragment do not decompose at initial stages of the interaction with water, but only a change in its ligands environment take place. First, labile chloride ligands are replaced by OH-groups through the stage of water addition followed by its deprotonation. Then, carboxylate ligands are removed due to their stronger trans-influence according to the data of proton magnetic resonance spectroscopy. At the final stage of hydrolysis, cis-[Re2(-Ala)2(H2O)2Cl4]Cl2 is converted to the Re(IV) derivatives, which is accompanied by the formation of ReO2nH2O precipitate according to the data of IR-spectroscopy. A maximum at 950 cm–1 is attributed to the Re=O vibration, and a band at 3450 cm–1 is ascribed to the stretching vibrations of OH-groups in water molecules.

128-133

Authors: S. Minu Xavier Sebastini, P. Daniel Nixon, C. Joseph Kennady

Nickel hydroxide is a promising material for supercapacitor application due to its relatively low cost, well-defined electrochemical redox nature and easy to prepare with different structural morphologies. In the present study, nickel hydroxide was cathodically deposited on a stainless steel surface from an electrolyte containing Ni(NO3)2 as a result of local increase in pH at the cathode. A nonionic surfactant (Pluronic P 123, HO(CH2CH2O)20(CH2CH(CH3)O)70(CH2CH2O)20H) was added to the solution in order to get enhanced nanocrystalline nickel hydroxide film. The film was characterized using scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction method and Fourier transform infrared spectroscopy to investigate its surface and morphological characteristics. The grain size of the as prepared nickel hydroxide was about 11 nm and this was achieved because of the presence of nonionic surfactant, which influences the microstructure of the deposit. Cyclic voltammetry was used to study the reduction and oxidation processes in the electrodeposited nickel hydroxide electrode, characterize the specific capacitance and evaluate the suitability of the synthesized films for supercapacitor application. The charge-discharge dependences were recorded to study the capacitive property of the material. The results showed that the prepared nickel hydroxide electrodes have specific capacitance of about 494 F/g.

140-147

Authors: L.I. Sliusarchuk, L.I. Zheleznova, O.O. Rogovtsov, S.V. Kuleshov, O.K. Trunova, T.V. Pavlenko

This work was aimed at the search for new molecular precursors capable of generating complex oxide materials during "soft" thermolysis. New heterometallic acetylacetonate complexes LnM(АА)5nD (Ln(ІІІ)=La, Nd; M(ІІ)=Co, Ni; AA – acetylacetone, D – H2O, '-dipyridyl) were synthesized as precursors to prepare oxide heterometallic structures. Their thermal stability was evaluated. To develop methods for the thermolysis of heterometallic complexes, the experiments were carried in which the thermolysis conditions were changed by varying the heating rate (from 5C min–1 to 20C min–1), the final heating temperature (up to 600C and 800C) and the exposure time at the final temperature (from 1 hour to 5 hours). It was established that the use of the thermolysis of binuclear -diketonates for the synthesis of cobaltates and nickelates of lanthanum (neodymium) allows significantly reducing the temperature (from 1000 to 800С) and the heat treatment time (from 12 to 1–3 hours) as compared with the solid-phase synthesis methods. We showed that there is the possibility to obtain the powders of cobaltates and nickelates of lanthanum (neodymium) from bimetallic acetylacetonate precursors LnМ(AA)52'-dipy. The composition of the synthesized oxide powders after heat treatment was controlled by using X-ray powder diffraction analysis. The study of the phase transformations during the thermolysis of heterocomplexes and a mixture of the corresponding monometallic complexes showed the formation of complex oxides LnCoO3 and Ln2NiO4, however their purity is higher in the case of using heterocomplexes. The study on the deposition of complex oxide structures of LnxMyOn on the granules of aluminum oxide from heterocomplexes LnМ(AA)5nD was carried out.

157-162

Authors: N.Yu. Strutynska, M.V. Maluk, M.S. Slobodyanik, T.Yu. Sliva, Y.O. Titov

The features of the formation of phosphate-vanadates of a general composition Sr9Ві(PO4)7–x(VO4)x (x=0, 2, 5, 7) under conditions of solid state reaction have been investigated in the temperature range of 400–820 (950)С depending on their composition. The influence of the ratio of initial components on the phase composition of crystal products was established. Single-phase samples of Sr9Ві(PO4)2(VO4)5 and Sr9Ві(VO4)7 were synthesized at the values x=5 and 7, which belong to trigonal system, space group R-3m. An increase in the amount of phosphate in the system (x=0 and 2) led to the formation of mixtures based on Sr3(PO4)2 (palmierite-related ones). FTIR spectra of the synthesized Sr9Ві(PO4)2(VO4)5 and Sr9Ві(VO4)7 showed that the vibration modes in the range of 890–790 сm–1 confirmed the presence of VO4-tetrahedra in their composition, while the modes of the РО4-tetrahedra were found in the range of 1150–890 сm–1. The investigation of the optical properties of the prepared single-phase phosphate-vanadates revealed that a partial isovalent substitution of phosphate by vanadate group in the Sr9Ві(PO4)2(VO4)5 matrix resulted in a decrease in the band gap from 3.12 еV to 3.0 еV (for Sr9Ві(VO4)7). This result can be used for the creation of efficient photocatalysts based on strontium- and bismuth-containing phosphate-vanadates.

172-176

Authors: R.E. Khoma, V.O. Gelmboldt, A.A. Ennan, V.M. Baumer, R.M. Dlubovskii, S.V. Vodzinskiy

It was established that the interaction in the system "sulfur (IV) oxide–tris(hydroxymethyl)methylamine (Tris)–water–argon" yielded tris(hydroxymethyl)methylammonium sulfite [(HOCH2)3CNH3]2SO3 (I). The obtained ammonium sulfite I has been characterized by the methods of elemental analysis, X-ray phase analysis, IR spectroscopy and mass spectrometry. Compound I crystallizes in the three-line space group P–1 with the following cell frame parameters: a=10.6227(17) Å, b=10.6714(12) Å, c=14.7461(19) Å, =110.392(11), =110.194(13), =91.034(12), V=1452.24 Å3, and Z=4. IR spectrum of the salt I reveals (SO) anion stretching vibrations (1 and 3, respectively) that are represented by the bands in the region of 1039–910 cm–1. Two bands of medium intensity at 503 cm–1 and 429 cm–1 and two weak bands at 519 cm–1 and 467 cm–1 are ascribed to the deformation vibrations (NСС), (ССО) and та d( ). The symmetric deformation oscillation of the s( ) anion is expressed as a medium intensity band at 619 cm–1. The presence of broad bands (OH) with a maximum of about 3400 cm–1 is observed from the cation eigenmodes in the IR region of compound I. There are wide structured bands of stretching vibrations of -groups participating in H-bonding in the region of 3290–2365 cm–1. The fluctuations of as,s( ) appear as two relatively intense bands at 1634 cm–1 and 1550 cm–1. Tris has a significant number of H-donor and H-acceptor centers in its structure which contributes to the process of sulfoxidation S(IV)S(VI) in the process of product I air-curing, unlike other ethanol amines.

187-193

Authors: M.V. Chayka, Z.F. Tomashyk, G.P. Malanych, V.M. Tomashyk, D.Yu. Panasyuk, O.M. Kamіnskiy

The features of the physicochemical interaction of the CdTe single crystals and ZnxCd1–xTe (x=0.04 and 0.1) solid solutions with K2Cr2O7–HBr–oxalic acid aqueous solutions were established using a rotating disc method under the reproducible hydrodynamic conditions for the first time. The diagrams "solution composition vs. dissolution rate" were plotted and the concentration limits of the solutions that exhibit polishing, selective or non-polishing effects were determined based on the experimental results and using the method of mathematical simulation. The kinetics of the dissolution process of the surfaces, the influence of the organic components and the semiconductors on the rate, the features of dissolution and the state of the treated surfaces were investigated. It was found that the interaction of these single crystals with polishing solutions is limited by the diffusion stage. A series of new slow etching compositions with a controlled dissolution rate of semiconductor materials (3.3–10.3 m min–1) was developed. The formulations of the etching solutions and the regimes of the chemical dynamic polishing were optimized. The state of semiconductors surface after chemical dynamic polishing was investigated by using metallographic analysis and atomic force microscopy.

201-204

Authors: O.B. Velichenko, V.S. Protsenko, K.M. Sukhyy

This communication is devoted to the 80th anniversary of the birthday of Professor F.I. Danilov, Editor-in-Chief of the journal "Voprosy Khimii i Khimicheskoi Tekhnologii". He has made a great contribution to the modern electrochemistry and metal finishing. The communication describes the main stages of the life and research activities of Prof. F.I. Danilov.