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

5-13

Authors: O. Berzenina, I. Osinna, N. Shtemenko

The information value of physicochemical methods for determining the change in the composition of the plants surface under the influence of toxicants was shown. Monochlorobenzene (MCB) is one of the most widespread representatives among chlororganic aromatic pollutant. Helophytes are used for the treatment of contaminated waters and are good absorbers of aromatics. The quantity of surface lipids of the surface lipids of the plants under the influence of MCB were analyzed by IR-spectra and gas chromatography-mass spectrometry (GC–MS) data in comparison with control plants grown on the distilled water. It was shown that the quantity of surface lipids increased by 8.5–17.8% for all species. According to the influence of monochlorobenzene on the composition of fatty acids, two groups of plants were found as follows: an increase in the content of C24:0–C32:0 was observed in the first group, and a sharp increase of C16:0 fatty acid took place in the second one. A decrease in the content of hydrocarbons in some species was noticed and changes in their heterogeneity were common for the most of exposed plants. The conclusion was drawn that FTIR spectra of surface lipids of Acorus calamus may be recommended for further investigations and the use in environmental monitoring.

18-24

Authors: F.I. Danilov, V.S. Protsenko, A.A. Kityk, D.A. Bogdanov, O.S. Baskevich

The electrodeposition of composite nickel–titania coatings from an electrolyte based on ionic liquid containing eutectic mixture of choline chloride and ethylene glycol has been investigated. The influence of the concentration of TiO2 nano-powder in electrolyte on the viscosity of the obtained colloidal system was studied. An appreciably higher viscosity of the studied electrolytes as compared with "common" water suspension electrolytes ensures a rather high dispersion stability and stability to particles sedimentation in colloidal systems. The effects of some electrolysis conditions (TiO2 concentration, stirring rate and current density) on the content of dispersed phase in composite were determined. The surface morphology of electrodeposited composite coatings was characterized. The deposited nickel matrix was shown to have a nanocrystalline structure. It was established that the microhardness and internal stresses of composite coatings increased at some specified contents of the dispersed phase in colloidal electrolyte (in comparison with "pure" nickel deposits). The photocatalytic performance of electrodeposited Ni–TiO2 coatings was evaluated towards the photochemical destruction of organic methyl orange dye.

31-36

Authors: H.I. Lavrenyuk, B.M. Mykhalichko, V.-P.O. Parhomenko

Based on the results of the crystal structure study of [Cu(H2NC2H4NH2)(H2NC2H4NHC2H4NH2)]SiF6 chelate complex which is the product of the interaction between a hardener of epoxy resins (polyethylenepolyamine, H2N[–C2H4NH–]nH, where n = 1 or 2) and copper(II) hexafluosilicate (a fire-retardant added to epoxy-amine composites), we carried out the quantum-chemical calculations of the thermochemical parameters (total energy of all chemical bonds, formation enthalpy and combustion heat) of the processes of complexing and burning that occur in H2N[–C2H4NH–]nH – CuSiF6 and [Cu(H2NC2H4NH2)(H2NC2H4NHC2H4NH2)]SiF6 – O2 systems, respectively. The ab initio quantum-chemical calculations have been performed using the restricted Hartree-Fock method with a 6-31G* basis set. It was ascertained that concurrent chelating Cu2+ ion of anhydrous copper(II) hexafluosilicate salt by both ethylenediamine (eda) and diethylenetriamine (deta) (the component parts of polyethylenepolyamine) and appearing five strong donor-acceptor bonds Cu(II)N allows very efficiently diminishing the combustibility not only of the coordinated molecules of the hardener of epoxy resins, but also of the modified epoxy-amine composites. This is in good agreement with the results of a derivatographic analysis and experimental determination of ignition point and self-ignition point of the [Cu(eda)(deta)]SiF6 crystal complex and polyethylenepolyamine. The obtained results justify the use of chelate complexes of transition metals salts with polyamines as efficient fire retardant-hardeners for the development of the self-extinguishing epoxy-amine composites.

44-49

Authors: O.M. Khomenko, B.P. Minaev

Potential energy curves of the ground state and a number of excited states of the ClO- and HOCl species along the photodissociation reaction channels are obtained on the basis of multireference configuration interaction, which correlate with the low-lying dissociation limits. The singlet–triplet nonadiabatic transition during the predissociation of the ground Х1+ state to the lowest limit О(3Р) + Cl-(1S) is predicted on the basis of the calculations results. In order to predict the possible importance of the singlet-triplet absorption in the HOCl molecule spectrum, we have presented potential energy curves for the ground singlet X1A' and the first excited triplet 13A'' states. The results show that atmospheric photochemistry of heavy halogen-containing compounds substantially depends on the singlet–triplet transitions and the inclusion of relativistic effects. Thermochemical ab initio calculations of ClO– as a possible product of HOCl molecule dissociation show that these compounds in the singlet ground state are stable enough. Our calculations based on multireference configuration interaction with regard to spin–orbit coupling indicate that the compounds are metastable.

58-63

Authors: Z.M. Yaremko, R.L. Bukliv

It is shown that the changes in local viscosity of water around ions can be revealed by the data on ions electrical mobility in their aqueous solutions. On the basis of these changes, an approach is suggested which involves the evaluation of the water structure in the nearest surroundings of these ions. The degree of hydration of ions can be quantified by the number of molecules retained near ions in the case of positive hydration and the number of molecules, which are repelled from ions in the case of negative hydration. The number of water molecules is calculated from the effective radius of the moving object (ion and associated water molecules, ion and repelled water molecules) provided the local viscosity of water around the ions is equal to the viscosity in the bulk water. It is confirmed that positive hydration is observed for Li+ and Na+ cations and F- anion, while negative hydration is typical of K+, Rb+, and Cs+ cations and Cl-, Br-, and I- anions. The obtained results are in a good agreement with the changes of entropy which are associated with the structural changes of water in surroundings of singly charged ions owing to their hydration, as well as with the formation of crystalline hydrates for these ions salts.

70-78

Authors: N.V. Nikolenko, A.V. Dubenko, E.Yu. Vashkevich, L.V. Dmitrikova

The kinetics of the process of sulfatization of altered ilmenite from the Malyshevskoye deposit in 85% sulfuric acid solution has been studied under isothermal conditions in the temperature range of 100 to 200C. The reaction products have been studied by XRD method and thermal analysis. The efficiency of titanium recovery in the sulfatization process at the temperatures of above 190C after 150–180 minutes is shown to be reduced. This can be explained by the formation of a polymer form TiOSO4, which is insoluble in acids. The rate constants as well as the activation energies of each stage were determined separately for titanium and iron in the approximation of a two-stage model of the sulfatization process with the rate determining steps of the chemical reaction and one-dimensional diffusion. It has been concluded that the temperature optimum of the process of sulfatization of altered ilmenite is determined by two following factors. It is necessary to raise the temperature of the reaction mixture to maximize the process rate, but the polymerization process of TiOSO4 is accelerated abruptly starting from 200C that leads to the formation of precipitate which is insoluble in acids.

90-95

Authors: I.V. Popova, O.I. Mayboroda, N.Yu. Zinchenko, N.O. Klimenko

We investigated the process of hydrolysis of inulin by citric acid for the use in food industry. The choice of citric acid as a catalyst of the hydrolysis process is determined by its relatively soft action on the plant objects during heating that provides the process of hydrolysis of a polysaccharide, but does not lead to the formation of a noticeable amount of by-products. The monitoring of the process was performed by the evaluation of reducing substances (RSs) in received products and by the thin-layer chromatography (TLC), in a fixed layer. The total content of carbohydrate substance and the composition of carbohydrates were determined by the high pressure liquid chromatography (HPLC). To identify optimum conditions of the hydrolysis process, the dependences of the completeness of the hydrolysis on the amount of the added citric acid, temperature and the duration of the process were studied at a constant starting concentration of chicory in the suspensions (30%). In all cases, a growth of the concentration of the RSs in the product of inulin hydrolysis was observed which is associated with an increase in the direct factors while the optimal values have been achieved (Сacid = 0.8%, t = 65С, τ = 120 minutes); a further increase of these values results in side reactions. The optimal regime for the hydrolysis of dried chicory powder (Сacid = 0.9–1.0%, t = 65С, τ = 120 minutes) was also established by the experimental study and mathematical analysis of the obtained data. The production schemes were developed based on the determined optimal parameters of the hydrolysis of raw chicory materials by citric acid, which ensure a maximal amount of valuable mineral and organic components of chicory in the final product.

105-112

Authors: D.E. Sidorov, E.P. Kolosova, A.E. Kolosov, I.A. Kazak

Engineering methods for estimating the kinematic parameters and reduction of an extrusion billet in the process of blow molding under conditions of gravity stretching are developed in this work. The interrelation between the components of the speed of the billet motion in its various sections and the extension coefficient with the geometric and technological parameters of the gravitational elongation process is established. It is shown that the rate of gravity extension is not constant and can vary many times in different sections of the polymer billet. It is established that the instantaneous rate of gravity extraction in the zone of melt exit from the extrusion head (die) can be up to 18% of the linear extrusion rate. At the same time, an increase in the velocity of the cross sections due to the gravitational stretching is the more significant, the longer the length of the polymer billet is. It is stated that the dynamic viscosity of the melt as well as the extrusion temperature is not a decisive factor which might significantly affect the shape of the billet under conditions of normal technological regimes. It is shown that the coefficient of gravitational extension changes by 16–17% with the change of the length of a polymer billet in the process of its production. For the volumetric productivity of the extruder of 102 cm3/s, the unevenness of the gravity extraction conditions of the extruded billet can be up to 14%. It is established that the unevenness of the conditions of the deformation of the extrusion billet increases with a decrease in the extruder's productivity, it can reach 33%.

121-126

Authors: O.V. Suberlyak, N.M. Baran, Yu.Ya. Melnyk, G.V. Yatsulchak

The patterns of modifying the surface of hydrogel films by the diffusion deposition of thin layers of polycaproamide–polyvinylpyrrolidone (PA-6/PVP) from a formate solution have been established. The relationship between the composition and properties of hydrogel membrane substrates, which are intended for the formation of composite membranes, was shown. An increase in the PVP content results in an increase in elasticity and a decrease in the mechanical strength of hydrogels. The effects of the composition of formate solution, contact time with the surface, temperature and conditions of subsequent evaporation of formic acid on the surface adsorption of PA-6/PVP have been determined. The influence of the surface adsorption of PA-6/PVP mixture on the physical and mechanical properties of the synthesized films has been investigated. An increase in the modification time of hydrogel membranes, and, consequently, an increase in the PA-6/PVP adsorption lead to an increase in the strength of membrane with asymptotic deceleration. The permeability of the synthesized composite hydrogel membranes based on 2-hydroxyethyl methacrylate (HEMA) and PVP copolymers modified by a layer of PA-6/PVP has been determined during the osmosis of sodium chloride from an aqueous solution. The osmotic permeability of the synthesized composite membranes in the case of sodium chloride somewhat decreases as compared with the hydrogel matrix, especially if the PA-6/PVP concentration in the modifying formate solution increases.