Cooperative effects in surfactant adsorption layers at water/alkane interfaces

In the present work, the properties of dodecyl dimethyl phosphine oxide (C12DMPO) at the water/decane interface are studied and compared with those obtained earlier at the interface to hexane. To simulate the interfacial behavior, a two-component thermodynamic model is proposed, which combines the equation of state and Frumkin isotherm for decane with the reorientation model involving the intrinsic compressibility for the surfactant. In this approach, the surface activity of decane is governed by its interaction with C12DMPO. The theory predicts the influence of decane on the decrease of the surface tension at a very low surfactant concentration for realistic values of the ratio of the adsorbed amounts of decane and surfactant. The surfactantrsquo;s distribution coefficient between the aqueous and decane phases is determined. Two types of adsorption systems were used: a decane drop immersed into the C12DMPO aqueous solution, and a water drop immersed into the C12DMPO solution in decane. To determine the distribution coefficient, a method based on the analysis of the transfer of C12DMPO between water and decane is also employed

Foaming binary solution mixtures of low molecular surfactant and polyelectrolyte

The lifetime of water solution foams of sodium dodecylsulfate (DDS, low molecular weight surfactant) and sodium carboxymethylcellulose (SCMC, polyelectrolyte) and their binary mixtures was experimentally investigated. The effects of ionic strength and acidity on the foam life were also determined. In binary solutions, a synergic effect of DDS and SCMC on the surface tension reduction, most likely resulting from the interaction of the surfactant with polymer, was found. The addition of NaCl into solution or increasing the ionic strength was found to decrease the surface tension and reduce interfacial mobility, hence increased foam lifetime. The relatively low lifetime of binary solution foams in acidic medium was attributed to the reaction between SCMC and acid, which resulted in relatively small reductions in the viscosity and consequently lowered the solution viscosity

Structure Formation of the Surface Layer of Soil as a Way to Prevent a Wind and Water Erosion

The present work describes the results of a study of structuring ability of water-soluble polymers such as polydimethyl diallyl ammonium chloride, saponification product of polyacrylonitrile (uniflok) and their interpolymer complex. On the kinetics of growth of Rehbinder’s plastic durability of coagulation structure of soil concentrated suspensions the effect of water soluble polymers and interpolymer complexes on the structure formation in the dispersions was studied. It was determined that the process is a two-step process which was caused by the adsorption step process: the binding of macromolecules with the soil surface by the random segments and conformational changes of macromolecules in the adsorbed layer. It was found that the soil stability structured by polymers against wind and water erosion increased with the concentration of water-soluble polymers. This is due to the increase of the structure formation in concentrated suspensions of soil in the presence of water soluble polymers. On the basis of the results it can be concluded that the treatment of mineral dispersions by water-soluble polymers alone or in the form of the interpolymer complex leads to a significant reduction of dust-and run-off of soil particles. The PDMDAAC/uniflok interpolymer complex in comparison with polymers reduces intensively the deflation which has a great economic and ecological importance

Optimization of polymerization process conditions during development of micro- and nanocapsules of hydrophobic agents based on Pickering emulsions

The polymerization process is one of the most important processes to obtain stable emulsions. This is especially important when the emulsion evaporates. In the work, the protocol of optimum polymerization conditions was developed, which comprises carrying out the polymerization at a temperature of 80°C using potassium persulfate as an initiator at a concentration 0.4 mM. It was found that the formed monodisperse particles with an average size of 200 nm have a distinct morphology capsules, which according cryo-SEM pictures have spherical shape, similar to the morphology of raspberry. These results are also consistent with the data of TEM images, whereby submicrocapsules were densely coated by silica particles. It was proved by zeta-potential measurements according to which, after polymerization the disperse systems become more colloidally stable and less prone to aggregation and sedimentation

Plykin-like attractor in non-autonomous coupled oscillators

A system of two coupled non-autonomous oscillators is considered. Dynamics of complex amplitudes is governed by differential equations with periodic piecewise continuous dependence of the coefficients on time. The Poincar\'{e} map is derived explicitly. With exclusion of the overall phase, on which the evolution of other variables does not depend, the Poincar\'{e} map is reduced to 3D mapping. It possesses an attractor of Plykin type located on an invariant sphere. Computer verification of the cone criterion confirms the hyperbolic nature of the attractor in the 3D map. Some results of numerical studies of the dynamics for the coupled oscillators are presented, including the attractor portraits, Lyapunov exponents, and the power spectral density.Comment: 11 pages, 9 figure

Novel process for coating textile materials with silver to prepare antimicrobial fabrics

The technology of applying a silver coating on fabric is presented. Tissue is wetted with a solution of copper sulphate, which is then reduced to metal-phosphide by phosphine treatment. Wetting can be carried out by immersing the fabric in a copper sulphate solution or spraying the solution onto the fabric using a sprayer. The subsequent processing step is the immersion of the fabric in a solution of silver nitrate, during this copper phosphide is transformed to a silver coating. The developed technology allows achieving a good grip of the fabric with a continuous silver films with a thickness from 40 to 600 nm. Using copper sulphate spray, coatings consisting of individual dots or clusters of silver were obtained. The silver coated tissues exhibited antimicrobial activity even after 10 washing

Nanoparticles of Sulfur as Fungicidal Products for Agriculture

Sulfur is a nonmetallic element necessary for life. Sulfur nanopartieles display unique physical and chemical feature because of effects such as the quantum size effect, mini size effect, surface effect and macro-quantum tunnel effect. So sulfur nanoparticles would present higher efficacies such as removal of heavy metals, radical-scavenging, antimicrobial activity, antioxidant and antitumor activities. It is used as a fungicide product in agriculture, also used in medicine, to obtain sulfur fertilizers and cosmetics industries, as well as in obtaining nanocomposite lithium batteries. In synthesis of sulfur nanowires with carbon to from hybrid materials with useful properties for gas sensor and catalytic applications. This work presents the results of obtaining the sulfur nanoparticles, which can be used in agriculture as a fungicide treatment. Sulfur nanoparticles were obtained by modifying the surface of sulfur by various surfactants including cetyltriammoniumbromide (CTABr), Sulfanol, Sodium Ligninsulfonate (CMN), Sodium salt of polynaphthalene sulphonic acid (NNO), water soluble polymer sodium carboxymethylcellulose (NaCMC), mineral mixtures and their compositions. The size and the structure of sulfur nanoparticles were determined by methods as LSA, XRD, SEM. Been studied the value of adsorption at the interface of solid/gas. It is shown that the nanoparticles have a sulfur monoclinic B-form, and their average size is in the range 500-1000 nm. The received products can be considered as perspective forms of application in agriculture