I. I. Lebedeva

Influence of the composition of acrylamide–acrylonitrile–2-acrylamido-2-methylpropanesulfonic acid terpolymer on its resistance to high temperatures and salts

The influence of the ratio of the acrylamide, acrylonitrile, and 2-acrylamido-2-methylpropanesulfonic acid monomeric units in the terpolymer on its resistance to elevated temperatures and sensitivity to calcium salts was studied. The influence of the terpolymer composition on the chemical transformations occurring under the conditions of thermal and hydrothermal treatment was studied by TGA and IR spectroscopy. The degree of hydrolysis of the terpolymers influences their resistance to CaCl2. The resistance of the terpolymers to CaCl2 additions at their concentrations of up to 7 wt % is preserved at the content of 2-acrylamido-2-methylpropanesulfonic acid units higher than 20 mol %. The revealed features allow optimization of the structure of polymer systems used in drilling lubricants.

Study of the effect of ammonium sulfate additives on the structure and photocatalytic activity of titanium dioxide

Thermal hydrolysis of titanium hydrochloride in the presence of ammonium sulfate added in a Ti: SO42− = 20: 1 ratio was used to obtain samples of mesoporous titanium dioxide with anatase structure, stable in a wide temperature range. The phase composition, porous structure, and morphology of the synthesized titanium dioxide powders were examined by X-ray phase analysis, IR spectroscopy, scanning electron microscopy, and low-temperature adsorption of nitrogen. The role played by sulfate ions in how the microstructure of titanium dioxide is formed was determined. The effect of the hydrolysis temperature on the structure of titanium dioxide being obtained and on its photocatalytic activity in the reaction of decomposition of Methyl Orange dye was examined.

Formation and structural phase transitions of mesoporous Al2O3 and TiO2/Al2O3 xerogels under hydrothermal conditions

We have studied the effect of the hydrothermal synthesis temperature on Al2O3 structure formation and examined the role of the phase composition of the precursor gel and surfactant in the formation of the pore structure of Al2O3. A technique has been proposed for the synthesis of TiO2/Al2O3 binary xerogels, and the effect of TiO2 content on the pore structure parameters and adsorption properties of TiO2/Al2O3 has been investigated.

Study of the effect of organo-substituted trialkoxysilanes on the textural and structural properties of mesoporous silica

The effect of additives of organo-substituted trialkoxysilanes: (3-aminopropyl)triethoxysilane (APTES), (2-cyanoethyl)triethoxysilane (CNETES), and tris(trimethylsiloxy)silane (TTMSS) as cosources of silica on its textural and structural properties was studied. The influence of organo-substituted trialkoxysilane additives on the variation of porous structure parameters of mesoporous silica during the hydrothermal treatment was demonstrated. The synthesized mesoporous silica samples were characterized by low-temperature nitrogen adsorption, X-ray powder diffraction, scanning electron microscopy, thermal and elemental analysis, and Raman spectroscopy.

Synthesis by radical polymerization and structure of drag reducing terpolymers based on acrylamide, acrylonitrile, and 2-acrylamido-2-methylpropanesulfonic acid

Terpolymers of acrylamide, acrylonitrile, and sodium 2-acrylamido-2-methylpropanesulfonate were prepared by radical copolymerization in aqueous solution. The terpolymers obtained are enriched in acrylamide units and depleted of acrylonitrile units relative to the initial monomer ratio. The acrylamide–acrylonitrile–sodium 2-acrylamido-2-methylpropanesulfonic acid terpolymers show high performance as drag reduction agents. Under the conditions of thermal, salt, and acid aggressions, the terpolymer containing 71.6 mol % acrylamide, 10.5 mol % acrylonitrile, and 17.9 mol % sodium 2-acrylamido-2-methylpropanesulfonate ensures drag reduction no less than 70%.

Antiturbulent properties of sulfomethylated polyacrylamide under the conditions of thermal, salt, and acid aggressions

Nonionic polyacrylamide with the weight-average molecular mass of 7 MDa was modified by sulfomethylation. The composition of sulfomethylated polyacrylamides was determined by iodometric titration, Fourier IR spectroscopy, thermal gravimetric analysis, and elemental analysis. The sulfomethylated acrylate polymers containing ≥19.9 mol % sulfo groups are resistant to brines containing up to 70 g L–1 CaCl2 at temperatures of up to 140°С and to hydrothermal treatment at 180°С. As shown by capillary turbulent rheometry under the conditions of thermal, salt, and acid aggressions, at the optimum concentrations of sulfomethylated polyacrylamide in the medium, сopt = 0.025–0.085%, the maximal extent of a decrease in the hydrodynamic resistance, DRmax, remains on the level of 71–80%, and the flow rate increment, ΔQ, is on the level of (22.01–28.85) × 10–6 m3 s–1.

Influence of the temperature-time conditions on the textural and structural properties of mesoporous silicon dioxide synthesized in an ammonia-alcohol medium

The conditions for the formation of mesostructural silica materials (MSMs) in the ammonia-alcohol media were determined. Mesoporous silicon dioxide was synthesized by the template liquid-phase condensation method at high concentrations of the surfactant. The effect exerted by temperature and time of the synthesis, autoclaving, and by organosilane additive [(trimethylsiloxy)silane] used in synthesis on the structural and textural properties of the mesoporous material was determined. The temperature-time conditions for the preparation of mesostructured silicon dioxide were optimized.

Influence of Medium Parameters and Acrylate Ionic Terpolymer Concentration on the Toms Effect

The influence of the solution ionic strength (up to 1.89 M), temperature (up to 413 K) and acidity (pH down to 1.65) on the drag reduction DR and flow rate increment ΔQ of an aqueous solution of the terpolymer containing 71.6 mol % acrylamide, 10.5 mol % acrylonitrile, and 17.9 mol % sodium 2-acrylamido-2-methylpropanesulfonate was studied by capillary turbulent viscometry. The intrinsic performance and the optimum concentrations of the terpolymer under these conditions were determined. The temperature dependence of the flow rate increment for the terpolymer solution passes through a maximum. The turbulence drag reduction for water flows at temperatures exceeding 373 K was demonstrated.

Reduction of the hydrodynamic resistance to turbulent water flow with copolymers of acrylamide, acrylonitrile, and 2-acrylamido-2-methylpropanesulfonic acid

The influence of the ratio of acrylamide, acrylonitrile, and 2-acrylamido-2-methylpropanesulfonic acid monomeric units in the terpolymer on its molecular-mass characteristics was studied. The influence of the copolymer composition on its resistance to the action of CaCl2 was determined. The capability of the synthesized terpolymers to reduce the hydrodynamic resistance to a liquid flow was evaluated with a laboratory capillary turbulent rheometer. The hydrodynamic resistance reduction effect depends on the molecular-mass characteristics of the terpolymers.

The effect of composition of the reaction medium on the structural-textural characteristics of mesoporous silicon dioxide

The conditions for the preparation of mesoporous silicon dioxide in water-alkali, alcohol-alkali, water-ammonia, alcohol-ammonia, and acid media were determined and its textural characteristics were studied.