Length Of Hydrocarbon Radical Research Articles

Влияние состава гидроксамовых кислот на показатели флотации перовскита.

On a sample of perovskite-bearing ore of the testing of reagents-collectors from the class of hydroxamic acids, differing in the structure of the hydrocarbon radical, was carried out. The reagents based on octanoic acid and acids of vegetable oils — coconut and tall oil — were considered. It is shown that in the alkaline pH range the rough flotation is more active, and a considerable amount of gangue minerals is transferred to the froth product. Strong attachment of the collector on all minerals determines low efficiency of re-cleaning operations in alkaline conditions. The optimum pH of flotation is pH = 6.2–6.5. Increase in the length of hydrocarbon radical above 10 carbon atoms leads to a significant decrease in the selectivity of the collector action. Reagents based on coconut and tallic acids actively float both perovskite and gangue minerals. Of the reagents considered, octylhydroxamic acid is characterized by the most optimal flotation properties and provides obtaining perovskite concentrate with TiO2 ~49–50 %.

Anti/de-icing performance of the one-step electrodeposited superhydrophobic surfaces: Role of surface polarity regulated by hydrocarbon radical length

• Superhydrophobic surface is prepared by one-step electrodeposition method. • Polarity of superhydrophobic surface is regulated by hydrocarbon radical length. • [CH 3 (CH 2 ) 16 COO] 3 Ce possesses better non-wettability and anti/de-icing features. • Cerium and –CH 2 group together contribute to the excellent low-polarity. • lower-polarity surface with ultra-low ice adhesion can be sustained by oxide layer. The superhydrophobic surfaces with different polarity regulated by hydrocarbon radical length were fabricated by a facile one-step electrodeposition method in order to survey the effect of surface polarity on anti/de-icing performance. The as-prepared superhydrophobic surface, electrodeposited in the solution composed of Ce(NO 3 ) 3 6H 2 O and stearic acid, displayed higher superhydrophobicity with a contact angle reaching 173.02 ± 1.02° and a rolling angle being only 1.5°. The ideal non-wettability was mainly attributed to the formed micro-nanostructures during the one-step electrodeposition process and the lower-polarity of [CH 3 (CH 2 ) 16 COO] 3 Ce with the extension of –CH 2 length. Furthermore, lower-polarity surface could induce smaller water-adhesion dissipation energy, resulting in the obvious reduction in the contact time (11.8 ms) of an impact droplet. In terms of the anti-icing performance, the icing delay time could reach 612.68 s at −15 ℃, and still had a higher value of 39.12 s even at −40 ℃, which could be also reflected by the statistical data of freezing temperature (-20.27 ℃). An ultra-low ice adhesion of 5.72 kPa was achieved on lower-polarity surface, meanwhile, the surface anti/de-icing cycle durability could be improved by 32% owing to the addition of an oxide layer. Understanding the influencing mechanism of surface polarity on anti/de-icing performance could provide theoretical guidance for the development of passive anti/de-icing technologies in aviation industry field.

The Surface Properties of Solutions of Dicationic Imidazolium Surfactants with Short Bridge Fragments

The pendant drop shape and oscillating pendant drop methods have been employed to study the surface tension and the dilatational rheological surface characteristics at the solution–air interface for aqueous solutions of dicationic imidazolium surfactants with extremely short bridge fragments. A high surface activity has been revealed for these surfactants. High values of the dilatational viscoelasticity modulus have been found for the surfactant solutions. The modulus values increase with a decrease in the length of bridge fragments and an increase in the length of hydrocarbon radicals in surfactant molecules.

SYNTHESIS AND INVESTIGATION OF PROPERTIES OF NANODISPERSED SYSTEMS BASED ON VINYL ACETATE

A method of producing nanodispersed systems, stabilized by the solvation mechanism, which consists of carrying out the emulsion polymerization with surface-active monomers – alkyletoksimaleinata, is developed. The influence of temperature, the ratio of monomers, the hydrocarbon radical length and number of ethoxy functional groups on the rate of the process of obtaining nanodispersions is analyzed. The study of the properties of synthesized nanodispersed systems and aggregate storage stability showed that all indicators are within certain State Standards. The spectrophotometric analysis of nanodispersions showed that emulsion polymerization occurred in all cases. Kinetics of decomposition of the initiator in aqueous solutions in the presence of surface-active monomer showed that alkyletoksimaleinata activates the stage of initiation of obtaining nanodispersed systems. Alkyletoksimaleinata proved to be more effective than widely used in emulsion polymerization the emulsifier OP-10. It is established that nanodispersed systems are stable during storage. The use of nanodispersed systems, modified by surface-active monomers, makes it possible to exclude the stage of plasticization by low-molecular compounds that degrade the electrical properties of the product. This leads to a reduction in the material and energy costs, to an increase in the life of the product, since in this case there is no exudation of the plasticizer, which worsens the quality of the product and causes environmental pollution. It is established that the main role in the stability of nanodispersed systems, modified by surface-active monomers, plays the hydration of particles. The technology of production of modified nanodispersed systems based on vinyl acetate and surface-active monomer is developed. The technological scheme of production of modified nanodispersed systems is arranged, the binding of the main apparatus is made. Rational use of raw materials will allow to obtain a higher yield of the product. The nanodispersed systems, modified by surface-active monomers, can be used in all areas where systems with conventional emulsifiers are used.

FLUORESCENCE CHARACTERISTICS OF RHODAMINE 6G AND RHODAMINE C IN WATER-MICELLAR SURFACTANT ENVIRONMENTS

The influence of cationic, anionic, nonionic surfactants and their mixtures on the fluorescence characteristics of rhodamine 6G and Rho-damine C solutions has been investigated. The fluorescence intensity of aqueous solutions of rhodamine 6G and in the presence of cetylpyridinium chloride and sodium dodecyl sulfate has almost unchanged throughout the pH range. The fluorescence intensity of aqueous and water-micellar rhodamine C solutions has been increased in the pH 1-4 range; the signal has been remained unchanged at high pH values. The studies have been carried out at pH 4 for rhodamine 6G and at pH 10 for rhodamine C. The fluorescence characteristics of water-micellar dye - surfactant - non-ionic surfactant systems have been performed at a concentration of Triton X-100 of 3.4·10‑2 mol/l. The interaction with cationic surfactants has shown differences character between the I=f(n) dependences for aqueous solutions of highly hydrophobic rhodamine 6G and more hydrophilic rhodamine C. The study of the effect of the hydrocarbon radical length on the intensity of the fluorescence of rhodamine 6G and rhodamine C has been carried out at two concentrations of cationic surfactants: under the condition of the formation of stoichiometric associates dye with cationic surfactant and in the region of the micellar concentrations of cationic surfactants. The character of the influence of the length of the hydrocarbon radical cationic surfactants on the fluorescence intensity of the dyes can be explained by the increasing role of hydrophobic interactions and the enhancement of solubilization in systems involving long-chain surfactants. The difference in the nature of the associates of rhodamine 6G and rhodamine C with hydrophobic and moderately hydrophobic cationic surfactants has been counterbalanced in the presence of Triton X-100. Reduction of fluorescence intensity of rhodamine 6G in domicile solutions of anionic sodium dodecyl sulfate has been established. The method of fluorescence detection of sodium dodecyl sulfate in reaction with rhodamine 6G has been proposed. The method has been tested in determining of anionic surfactants in the waters after washing clothes.

MECHANICAL PROPERTIES OF SERVOVITE FILMS FORMED IN DURING FRICTION AQUEOUS SOLUTIONS OF CARBOXYLIC ACIDS

Introduction. The effect of the organic component nature in the systematic series of monocarboxylic acids on the tribological characteristics of the brass-steel friction pair in aqueous solutions is described. Dependence of the mechanical-and-physical properties of the antifriction films formed during friction on the nature of the lubricating composition is investigated. The work objectives are to study the applicability of carboxylic acids as an antifriction lubricant component; to assess their effect on the mechanical properties of the servovite film formed under the brass – steel friction.Materials and Methods. Tribological studies of the brass-steel friction pair on the AE-5 end-type friction machine are carried out. Roughness parameters of the servovite film were determined through the optical profilometry. The microgeometry and the object structure at the nanoscale were considered using atomic force microscopy. The mechanical characteristics of the antifriction film were investigated using the instrument nanoindentation.Research Results. Tribological characteristics of the brass-steel tribocoupling and mechanical-and-physical properties of the servovite film formed during friction in the “brass – aqueous solution of carboxylic acid – steel” system were studied. It is established that the friction factor reduces when increasing the hydrocarbon radical length. The dimensional effects are found in the mechanical and tribological properties of the servovite film formed on the surface of the friction interaction in the carboxylic acids.Discussion and Conclusions. The study results show that the friction interaction on the wearing surface in the aqueous solutions of carboxylic acids forms a nanostructured servovite film which drops the friction factor. Its mechanical, physical and tribological parameters depend on the composition of the model lubricating medium. It is determined that the local mechanical-and-physical properties depend on the method of producing the servovite layer, the load and the size of the deformation zone. The results obtained can be used in the development of lubricants.

Enzymatic Synthesis of Fatty Esters by Lipase from Porcine Pancreas

An enzymatic synthesis of aliphatic esters of butyric acid in the waterless environment of organic solvent hexane was carried out with use of the enzyme preparation lipase from porcine pancreas. Aliphatic alcohols with different length of hydrocarbon radical (C4-C11) were used as substrates. Conversion of the esters depending on time of the process and concentration of the enzyme was defined at 30°C of the process. It was found that an increase in length of the hydro carbonic radical of alcohol and branching of a chain complicated enzymatic synthesis. For the lower alcohols the conversion reach more than 90%.

СВЯЗЬ СТРУКТУРЫ И ТРИБОЛОГИЧЕСКИХ ХАРАКТЕРИСТИК ДИАЛКИЛДИТИОФОСФАТОВ ЦИНКА

The article considers the dependence of the antiwear and antifriction action dialkyldithiophosphate zinc (ZDDP) from the value of hydrocarbon radicals. Experimentally studied the friction parameters in sliding contact, simulating a radial bearing. The value of the contact pressure, which implements a hydrodynamic modes depends on the roughness of the surfaces. Dedicated mode is boundary lubrication, which differs from the hydrodynamic and boundary friction regimes. This mode is characterized by a relatively constant coefficient of friction and a small amount of wear. As a criterion for evaluation of antiwear properties, used the value of contact pressure at which the transition from the boundary lubrication regime to the regime of boundary friction. It is found that the transition to the boundary friction regime occurs at different contact pressures for the same type of ZDDP with different length of hydrocarbon radicals. When using zinc dihexadecylnaphthalene the transition to boundary friction occurs at much larger values of contact pressure than when using dioctylphthalate zinc. The results are discussed taking into account the mechanism of adsorption of components of lubricating oils on metal surfaces. The dependence of the antiwear action of ZDDP from the length of the hydrocarbon radicals correspond to their influence on the parameters of a multi-molecular adsorption layer. The data on the influence of ancillary components on the structure and mechanical properties of adsorption layers, and on the rheological properties of lubricants in friction units. It is shown that the introduction of a hydrocarbon base oil ZDDP along with other components consisting of linear molecules with a sufficiently long hydrocarbon radicals, affects the range of contact pressures, which implements a hydrodynamic mode of friction. As an example, used hexadecanol diester and maleic acid. The inclusion of such components in the lubricating oil contributes to the implementation of the hydrodynamic regime, but does not affect the transition from boundary lubrication to boundary friction.

THERMAL STABILITY OF 1,8-NAPHTHALIMIDE TETRAALKYLAMMONIUM SALTS

The synthesis of tetraalkylammonium 1,8-naphthalimides was performed in benzene-5% NaOH aqueous solution at room temperature by anion exchange and subsequent extraction of the desired salts into the organic phase with yields of 93-98 %. It is determined by thermogravimetric analysis that tetraalkylammonium salts of 1,8-naphthalimides are thermally stable to 110-140 °С. Endothermic peaks without mass loss are observed on the thermogravimetric curves of all synthesized salts at a range of 110-140 °С that correspond to the melting points of the salts. The first mass loss is observed at 140-230 °С and is accompanied by endothermic peak at 170-200 °С on DTA curve; complete mass loss is observed at 240-300 °С and corresponds to exothermic peak at 260-270 °С. The thermogravimetric curve form of a naphthalimide salt depends on the length of hydrocarbon radical of a tetraalkylammonium cation. Thermal analysis data for tetrabutyl- and tetrahexylammonium salts conform to predicted mechanism of Hoffmann elimination that lead to corresponding naphthalimide, tertiary amine and alkene as reaction products. Significant deviations are only detected in the case of tetraoctylammonium salts, that can be explained with formation of high boiling trioctylamine during elimination.

Influence of hydrophobicity of alkyl sulfate and alkylpyridinium surfactants on the transport characteristics of plasticized polyvinyl chloride membranes

The ion transport of homologues of alkyl sulfate anions and alkylpyridinium cations through polyvinyl chloride filtration membranes (molecular sieves) under the conditions of diffusion mass transfer and direct current has been investigated. The quantitative characteristics of membrane transport, such as the permeability, diffusion, and partition coefficients; ion flux, selectivity, sorption capacity, and recovery, have been calculated. The effect of the hydrocarbon radical length of ionic surfactants on the quantitative characteristics of membrane transport has been revealed. It has been found that molecular sieves can be used for the separation of surfactant homologues.

Особенности диффузии гомологов алкилпиридиния через поливинилхлоридные молекулярные сита

The process of alkylpyridinium homologous transfer through polyvinylchloride plasticized nanofiltration membranes (molecular sieves) under self-diffusion and direct current conditions. Quantitative characteristics of membrane transport: the coefficients of permeability, diffusion, the distribution coefficient, ion flux, were calculated. The dependences of the volume properties of nanofiltration membranes from the hydrocarbon radical length in the alkylpyridinium homologous in membrane solutions and pore formers were shown.

Основные характеристики полимерных пластифицированных нанофильтрационных мембран на основе гомологов алкилпиридиния

Quantitative characteristics of alkylpyridinium homologues membrane transport through polyvinylchloride plasticized nanofiltration membranes (molecular sieves) under self-diffusion and direct current conditions were calculated. The dependences of the selectivity, the sorption capacity, the degree of enrichment of nanofiltration membranes from the hydrocarbon radical length of the alkylpyridinium homologous in membrane solutions and pore formers were shown. The separation of alkylpyridinium homologous by molecular sieves was conducted.

Relaxation processes of the structural rearrangement of clusters in liquids: 1,2-ethanediol, 1,2-propanediol, and 1,2,6-hexanetriol

The dielectric relaxation spectra (DRS) of 1,2-ethanediol, 1,2-propanediol, and 1,2,6-gexanetriol are analyzed in terms of the Dissado-Hill (DH) model in a wide range of temperatures, with all parameters required for calculating the cluster dipole moments being determined within the DH molecular model itself. The dependence of the equilibrium and relaxation properties of DRS on the hydrocarbon radical length and the number of OH groups is studied. The dipole moments of the clusters are calculated. It is shown how the roles of the processes of intracluster rearrangement are redistributed due to the break of hydrogen bonds and fluctuation processes of synchronous exchange of molecules between the clusters.

Influence of the nature of liquid anion exchanger on the selectivity of anion selective electrodes

Selectivity coefficients of ion-selective electrodes on the basis of liquid anion exchangers, a quaternary phosphonium salt, and 20 higher quaternary ammonium and other nitrogen-containing salts differing in the length of hydrocarbon radicals, the nature of the quaternary nitrogen atom, and the presence of polar groups near to the exchange center with respect to 17 mineral, organic, and metal complex anions are presented. The effect of the nature of the anion-exchanger on the anion selectivity is discussed.

Local dynamics of micelles of new long-chain surfactants in aqueous media

The molecular dynamics, organization, and phase state of aqueous solutions of new long-chain cationic surfactants with saturated hydrocarbon radicals (from C16 to C22) containing one or two hydroxyl groups in their polar heads are studied by the spin-probe EPR spectroscopy. In the region of micellar solutions, local mobility of surfactant molecules slightly changes with an increase in the length of hydrocarbon radical, whereas the order parameter of micelles increases notably. The addition of two hydroxyl groups to the polar part of long-chain (C22) surfactant molecule considerably decreases local mobility and increases the ordering of micellar system compared to the micelles of analogous surfactant with one hydroxyl group. Phase transition from micellar to a solid state is observed in this system with a decrease in temperature. The addition of KCl to aqueous surfactant solution lowers the local mobility, increases the order parameter of micelles, and can cause changes in the phase state of a system. In the presence of salt, the correlation time of probe rotation and its order parameter depend on surfactant concentration. Apparently, this is explained by changes in the shape of micelles upon variations in surfactant concentration.

Extraction of copper(II) from weakly acid and ammonia media with N′,N′-dialkylhydrazides of aliphatic carboxylic acids

Dependence of physicochemical properties of N′,N′-dialkylhydrazides of aliphatic carboxylic acids (solubility in kerosene, acid-base properties) on the length of hydrocarbon radicals in the functional group was studied. The extraction capacity for copper(II) salts in weakly acid and ammonia media was examined in the range from pH 5–11 to a NH3 content of 2.7 M. The capacity of the organic phase for copper(II) and re-extraction conditions were determined for the example of N′,N′-dibutylhydrazide of octanoic acid.

Effect of colloidochemical properties of template on the formation of the structure of mesoporous silica molecular sieves

A “homologous” series of mesoporous silica materials of MSM-41 type whose X-ray characteristics change in proportion to the length of hydrocarbon radical of template surfactant is synthesized using alkylpyridinium halides and sodium silicate. The correspondence principle of the state of the aggregation of micellar templates is used on synthesis for the first time. The influence of colloidochemical properties of surfactant solubilizer and solubilizate on the structuring ability of bitemplate (solubilization) composition is analyzed.

The Kinematic Viscosity of Binary Liquid Mixtures of n-Nonane with Propan-1-ol, Butan-1-ol, and Pentan-1-ol over the Temperature Range 193.15–313.15 K

The kinematic viscosity of n-nonane mixtures with propan-1-ol, butan-1-ol, and pentan-1-ol was measured over the temperature range 293.15–313.15 K. For all systems, negative deviations of viscosity from additive values were obtained; the deviations increased in magnitude as the temperature and alkan-1-ol hydrocarbon radical length increased. The activation energy of viscous flow was calculated in terms of the Eyring theory and free volume theory in the usual and extended (with the inclusion of molecular association) variants at equimolar mixture compositions. The behavior of the concentration dependences of viscosity and the activation energy of viscous flow in alkan-1-ol-n-alkane mixtures was found to be controlled by molecular association processes.

Effect of supercritical water density on the rate constant of aliphatic nitrocompounds decomposition

It was shown experimentally that the rate of aliphatic nitrocompounds decomposition in supercritical water (SCW) depends on pressure/density at constant temperature. The SCW density dependence of the apparent rate constant of decomposition for each of three compounds under consideration (nitromethane, nitroethane and 1-nitropropane) was found to correlate with the density dependence of the H 3O + concentration in dissociated SCW. The rate constant of RNO 2 decomposition in SCW decreased with increasing the length of hydrocarbon radical R.

Epoxidation of styrene with hydrogen peroxide in the presence of polymer-supported quaternary ammonium salts and peroxo complexes of W(VI)

Quaternary ammonium salts immobilized onto poly(2- N, N-dimethylaminoethyl) methacrylate and a mixed network of poly(oxyethylene) and poly(4-vinylpyridine) were prepared. These salts were characterized by an elemental analysis, IR, 1H and 13C NMR spectroscopy. The catalytic activity of the polymeric complexes was studied in the epoxidation of styrene as a model reaction. The system under study consisted of a water-immiscible solvent, aqueous hydrogen peroxide and Na 2WO 4/H 3PO 4. The catalytic activity of the polymeric ammonium salts depends on the kind of support employed, as well as on the length of hydrocarbon radicals and the nature of the anion. An increase in the selectivity of the reaction as compared to a system with non-immobilized salts is observed.