Influence Of Surface Active Agents Research Articles

Heat Transfer Enhancement in Separation Process of Ethanol from Ethanol Water Mixture by Using Surfactants

Here the investigations are done while distillation of ethanol-water mixture for separating ethanol from fermentation process. Focus is to study reduction in time required and hence saving in energy for the distillation process of ethanol-water mixture under the influence of surface-active agents (Surfactants). This novelty is from observation of these surfactants to enhance heat transfer rate because of surface tension reduction in aqueous solutions. SDS (Sodium Dodecyl Sulphate), NH4Cl (Ammonium Chloride) and SLBS (Sodium lauryl benzene sulphonate) surfactants in different concentration are experimented. The concentration of these surfactant is varied from 1700 ppm to 2800 ppm. This range is decided by observing critical micelle concentration of used surfactants. Results showed that time is reduced and hence energy consumption is also reduced. Results shown by NH4Cl are found to be more useful as it is ecofriendly surfactant which is not affecting ethanol-water mixture. Use of ammonium chloride as surfactant in distillation is actually useful to reduce energy without hampering the quality of process is the novelty of this work.

Heat Transfer Enhancement in Separation Process of Ethanol from Ethanol Water Mixture by Using Surfactants

Here the investigations are done while distillation of ethanol-water mixture for separating ethanol from fermentation process. Focus is to study reduction in time required and hence saving in energy for the distillation process of ethanol-water mixture under the influence of surface-active agents (Surfactants). This novelty is from observation of these surfactants to enhance heat transfer rate because of surface tension reduction in aqueous solutions. SDS (Sodium Dodecyl Sulphate), NH4Cl (Ammonium Chloride) and SLBS (Sodium lauryl benzene sulphonate) surfactants in different concentration are experimented. The concentration of these surfactant is varied from 1700 ppm to 2800 ppm. This range is decided by observing critical micelle concentration of used surfactants. Results showed that time is reduced and hence energy consumption is also reduced. Results shown by NH4Cl are found to be more useful as it is ecofriendly surfactant which is not affecting ethanol-water mixture. Use of ammonium chloride as surfactant in distillation is actually useful to reduce energy without hampering the quality of process is the novelty of this work.

Influence of surface active agent on the size of metal powder particles during their ball milling in a planetary mill

The paper presents the results of a study of the influence of surface active agent during the ball milling of metal powders in a planetary mill. It is shown that the mass fraction of the surface active agent in the powder mixture under study affects the size of the particles being treated, depending on the time of processing. The particle size distribution, the specific surface area were determined, and the surface morphology of the initial and ball milled particles was studied.

Influence of surface-active agents on Ni–ZrO<sub>2</sub> nanocomposite coatings

Influence of surface-active agents on Ni–ZrO<sub>2</sub> nanocomposite coatings

The influence of surface-active agents in gas mixture on the intensity of jet condensation

The report presents: the methodology of calculation of contact condensation of steam from the steam-gas mixture into the stream of water, taking into account: the mass flow of steam through the boundary phase, particularly the change in turbulent transport properties near the interface and their connection to the interface perturbations due to the surface tension of the mixture; the method of calculation of the surface tension at the interface water - a mixture of fluorocarbon vapor and water, based on the previously established analytical methods we calculate the surface tension for simple one - component liquid-vapor systems. The obtained analytical relation to calculate the surface tension of the mixture is a function of temperature and volume concentration of the fluorocarbon gas in the mixture and is true for all sizes of gas molecules. On the newly created experimental stand is made verification of experimental studies to determine the surface tension of pure substances: water, steam, C3F8 pair C3F8, produced the first experimental data on surface tension at the water - a mixture of water vapor and fluorocarbon C3F8. The obtained experimental data allow us to refine the values of the two constants used in the calculated model of the surface tension of the mixture. Experimental study of jet condensation was carried out with the flow in the zone of condensation of different gases. The condensation process was monitored by measurement of consumption of water flowing from the nozzle, and the formed condensate. When submitting C3F8, there was a noticeable, intensification condensation process compared with the condensation of pure water vapor. The calculation results are in satisfactory agreement with the experimental data on surface tension of the mixture and steam condensation from steam-gas mixture. Analysis of calculation results shows that the presence of surfactants in the condensation zone affects the partial vapor pressure on the interfacial surface, and the thermal conductivity of the liquid jet. The first circumstance leads to deterioration of the condensation process, the second to the intensification of this process. There is obviously an optimum value of concentration of the additive surfactants to the vapour when the condensation process is maximum. According to the developed design methodology contact condensation can evaluate these optimum conditions, their practical effect in the field study.

Covering ability of aluminum pigments prepared by milling processes

This paper deals with the influence of milling regimes on the development of a lamellar structure of aluminum pigment particles. A group of parameters describing the degree of fineness and morphology of the pigment particles were monitored simultaneously. The experiments were carried out using a semi-pilot milling plant with a vibrating mill and a ball mill. Based on the experiments, a criterial non-dimensional relationship was outlined. The relationship generalizes the influence of milling process conditions on the lamellar structure of pigment particles. At the same time, an equation which limits milling time used for the milling process was outlined. This equation solves the problem posed by the risk of destroying the lamellar structure of the particles over time. The theory of metal working was applied as an analogical base for establishing the efficiency of the milling process with respect to energy demand. In addition to basic process parameters, the significant influence of surface active agents on pigment lamellar structure was studied.

Investigation of surfactant effect on the bubble shape and mass transfer in a milli-channel using high-resolution microfocus X-ray imaging

In this paper we present an experimental study on the influence of surface active agents (surfactants) on Taylor bubble flow in a vertical millimeter-size channel. Moreover we give a short review on the subject and previous investigations. We investigated the shape and dissolution rate of individual elongated carbon dioxide Taylor bubbles, which were hydraulically fixed in a downward flow of water. Bubble shape and dissolution rate was determined from microfocus X-ray radiographs. From the shrinking rate we calculated the liquid side mass transfer coefficient.The results show that the presence of surfactants causes a change of the bubble shape and leads to a slight increase of the liquid film thickness around the bubble and as a result the elongation of contaminated bubbles. In addition, the comparison of clean and contaminated bubbles indicate that presence of surfactant has a more significant impact on the dissolution rate of small bubbles. Furthermore, applying different concentrations of surfactant reveals that in our case, where surface coverage ratio of surfactant on the bubbles is high, increase of contamination does not have a noticeable influence on the mass transfer coefficient of bubbles.

The effect of surfactant above and below the critical micelle concentration (CMC) and the mathematical models used to determine the kinetics of drug release from the matrix system

The liberation of propranolol HCl from a controlled release matrix, containing the hydrophilic polymer, sodium carboxymethylcellulose (NaCMC) and the hydrophobic polymer, Eudragit RL 100 (RL 100) as excipients, was studied. The influences of surface active agents on the dissolution rate of the drug were examined. Tablets were made by direct compression methods. The dissolution tests were performed by using the basket method. The incorporation of the cationic surfactants within the matrices increased the drug release until the critical micelle concentration (CMC). While, after the CMC, the increase in drug release was to a lesser extent. The incorporation of the anionic surfactants reduced the release rate of the drug from the matrices. At the CMC, the percent of drug release from the matrices were approximately the same with the matrices without the surfactants. While an increase in drug release was observed above the CMC of the anionic surfactants. The data obtained from in vitro drug release studies were plotted according to three kinetic models to study the release kinetic. These were zero order release, the first order release and the Higuchi equation. Zero order release of the drug was observed in all the formulations. The release mechanism was influenced considerably by the ratio of the excipients. Key words: Propranolol HCl, controlled release, critical micelle concentration (CMC), dissolution, dissolution rate kinetics, surfactant.

The Influence of Surface-Active Agent on the Micro-Morphology and Crystallinity of Spherical Hexagonal Boron Nitride

This search used the low-cost boric acid and borax as a source of boron, urea as a nitrogen source, surface-active agent Dodecyl benzenesulfonic acid (SDBS) as a dispersant, and thus prepared different micro-morphology and crystallinity hexagonal boron nitride powders under a flowing ammonia atmosphere at a nitriding temperature of 900 °C. The effect of the surface-active agent (SDBS) content on the crystallinity and micro-morphology of hexagonal boron nitride powders was studied, and the corresponding relationship between micro-morphology and crystallinity was explored. The results showed that under a certain synthetic process (900 °C for 3 h), the surfactant content had affected the crystallinity and micro-morphology of h-BN powders. Without the added surfactant, the graphitization index (GI) was 3.61, and micro-morphology of h-BN powders. was spherical, the distribution of ball diameters was uneven, and there was also significant particle agglomeration, with some particles even exhibiting adhesion, sintering necks, and high sphericity and diameter. When the added SDBS percentages were 2%, 4% and 6%, the graphitization index (GI) decreased to 2.98, 2.58 and 2.41 respectively: the corresponding crystallinity improved significantly. When the surfactant SDBS content was higher (10%), the diameter distribution of the h-BN powders was even, but there was evidence of agglomeration of particles and particle adhesion. The crystallinity decreased when the GI value was increased to 4. When the surfactant SDBS content was 6%, the dispersion of h-BN powders was at its optimum, and the particle size distribution was at its most uniform. Meanwhile the GI value was at its lowest, and the crystallinity at its highest.

Simplified modeling of the influence of surfactants on the rise of bubbles in VOF-simulations

A momentum jump condition is derived which models the influence of surface active agents at fluid interfaces due to Marangoni stresses. Underlying assumptions are quasi-stationary shape and surfactant distribution. The model is simple to implement into sharp interface two-phase flow solvers and VOF-based numerical simulations show that the effect of the jump condition is comparable to stagnant cap type models for small bubbles. An explicit cap angle is not needed, making it applicable to non-symmetric interface geometries, where a cap angle is hard to define. This approach via a modified interfacial momentum jump condition is also suitable for Front tracking or Level Set methods.

Cell surface properties and fatty acids composition of Stenotrophomonas maltophilia under the influence of hydrophobic compounds and surfactants

Surface properties of newly isolated Stenotrophomonas maltophilia strain 6 were tested. The bacteria were stored in two different ways to determine the influence of hydrocarbons and surfactants on surface and enzymatic characteristics of the isolated strain. The influence of surface active agents, natural and synthetic, on membrane's lipid composition and cell surface hydrophobicity (CSH) was investigated. Our results indicate that long-term contact with diesel oil as a hydrophobic sole carbon source leads to the increased enzymatic activity of S. maltophilia strain 6 as well as to modification of fatty acids profiles and its facility to adhere to hydrophobic compounds. Among surfactants there were saponins and Triton X-100 which changed the composition of fatty acids the most, increasing the amount of branched acids. The comparison of fatty acid profiles with CSH of systems with diesel oil, rhamnolipids, saponins and Triton X-100 points out that the growing amount of hydroxy fatty acids corresponds to lower hydrophobicity. Moreover, CSH is a dynamic parameter which can change during cultivation of microorganisms.

Influence of Surfactants on Release of Chlorhexidine from Hydrogels

Abstract In Slovakia chlorhexidine is available in dosage forms of solutions, creams and pastes but not in the form of hydrogels, though they are modern drug forms with many positive properties. Therefore, in this article possibilities of its formulation into hydrogels are studied. In particular, two research aims were followed. The first consisted in study of an influence of surface active agents on the release of chlorhexidine dihydrochloride from chitosan hydrogels and the second one was to design a formulation of hydrogels for local delivery of chlorhexidine to the oral cavity. To this end, surfactants from the group of alkyltrimethylammonium bromides with the length of alkyl chain C6–C18 which occupy a dominant position in the indication group of antiseptics and disinficients were analyzed with intention to use them in preparation of hydrogels. Hydrogels were prepared with 2.5% (w/w) gel-forming agent chitosan. Both the active agent and surfactants were used in 0.1% (w/w) concentration. It is shown that the surface active agents with short alkyl chain are suitable for development of chlorhexidine dihydrochloride hydrogels with controlled release.

Preparation of nanometer complex oxide of Ce X Zr1−X O2 by mechanically activated solid state chemical reaction

Nanometer cerium-zirconium oxide solution Ce1−XZrXO2 was synthesized by mechanically activated solid state reaction at middle-low temperatures, with Ce2(CO3)3, ZrOCl2·8H2O and H2C2O4·2H2O as raw materials. The crystal structure and microstructure of the nanometer Ce1−XZrXO2 were studied with X-ray diffractometry (XRD) and transmission electron microscope (TEM). The results show that the product is single-cubic-phase solid solution with an average crystal size 19.64 nm. In this article, the influence of surface active agent is also evaluated. Mechanically activated solid state reaction for the preparation of Ce1−XZrXO2 is a new technique of green chemistry without solvent and waste.

Towards stresses and strains in the respiratory system

This paper is concerned with coupled problems in the human respiratory system with emphasis on mechanical ventilation. We focus on the modeling aspects of pulmonary alveoli and the lower airways against the background of acute lung diseases. In this connection occurring stresses and strains are of substantial interest. For the first generations of the bronchial tree, a geometry based on human computer tomography scans obtained from in-vivo experiments is employed. The deformability of airway walls is taken into account to study airflow structures and airway wall stresses for a number of different scenarios. Therefore we carried out fluid-structure interaction (FSI) simulations under transient incompressible flow conditions. Both models for healthy and diseased lungs are studied under normal breathing as well as under mechanical ventilation. Our alveolar model is based on three-dimensional artificial random geometries generated with the help of a new labyrinthine algorithm ensuring preservation of overall minimal mean pathlength. A polyconvex hyperelastic material model incorporating general histologic information is employed to realistically describe alveolar parenchymal tissue properties. The influence of surface-active agents (the so-called surfactant) on the overall mechanical behavior of pulmonary alveoli is investigated. For this purpose an adsorption-limited model relating surface stresses to the interfacial concentration of surfactant is used.

Features of the extraction of essential oils from plant raw material in the presence of surface-active agents

It has been established that the influence of surface-active agents (SAAs), on the extraction of essential oils (EOs) is connected with a fall in the surface tension of water, which facilitates the process of steeping, wetting, and swelling of plant raw material and also the solubilization of the EOs in micellar solutions of SAAs.

Influence of Surface Active Agents on the Crystallisation Kinetics under different Stirring Conditions

Influence of Surface Active Agents on the Crystallisation Kinetics under different Stirring Conditions

Influence of surface-active agents on the thinning of a vertical liquid film

Influence of surface-active agents on the thinning of a vertical liquid film

Influence of the Electrolyte on Tracking Breakdown of Organic Insulating Materials

This paper describes the influence of the electrolyte on tracking breakdown of organic insulating materials by the IEC (International Electrotechnical Commission) 112 Method. Two different kinds of electrolyte with surface active and non-surface active agents have been employed to study the influence of wetting agents on tracking breakdown. The effect of surface active agents on tracking breakdown of organic insulating materials with various contact angles is shown. Increasing applied voltage changes the location of the dry band formed on the sample's surface so that the droplet number to tracking breakdown does not always decrease with increasing applied voltage. For samples with lower contact angle, the violet corona discharge occurs locally across the dry band, tending to approach the surface of the samples. Consequently, the number of droplets to discharge inception and carbon formation are decreased for samples with low contact angle. There is a substantial influence of surface active agents on droplet number to tracking breakdown.

The influence of surface-active agents on kaolinite

The influence of surfactants (CTAB and SDS) on suspensions of monoionic kaolinite (Na+ and H+ form) was investigated by adsorption, sedimentation, turbidity, electroosmosis, and rheological measurements, at pH = 3.3 and 10.0. Only small differences are found between the Na+ and H+ forms of the kailinite. The data can be accounted for satisfactorily by a mathematical model based on the DLVO theory for face-face, edge-edge, and edge-face interactions, if some assumptions on the local ψδ potentials near edge and face type surfaces are introduced.

The Wettability of Scoured and Dried Cotton Fabrics

The effect of scouring and drying on the wettability of cotton fabric is examined. The phenomenon of hydrophilicity is mainly determined by the competitive effects of spreading among the fibers and absorption in the fibers. Special attention is paid to the influence of surface active agents. A number of tests covering both aspects of the wetting process are discussed.