Effect Of Surface-active Substances Research Articles

Effect of surface-active substances on the surface charge density of purple membrane fragments

The surface charge density of purple membrane fragments and its alteration upon treatment of purple membranes with several surface-active substances [sodium dodecyl sulphate (SDS), cetylpyridinium chloride (CPC) and 3-[(3-cholamidopropyl) dimethylammonio]-1-propane-sulphonate (CHAPS) were examined by use of 9-amino-acridine fluorescence.The value of the surface charge density of native purple membrane fragments (0.8 electric charges/nm2) obtained by this method is comparable to previously reported values and in agreement with the structural model of the purple membrane.An increase followed by a decrease in the negative surface charge density was observed after treatment of purple membranes with the negatively charged surfactant SDS within the concentration range 0–5 mM, whereas treatment with the positively charged surfactant CPC and zwitterionic derivative of cholic acid (CHAPS) led to a decrease in the surface charge density. The large reduction of the surface charge density after treatment of purple membranes with CHAPS (i.e. partial delipidation of purple membranes) proves the significant contribution of the negative charges of the lipid polar head groups to the negative surface charge of purple membranes.

Effect of surface-active substances on the crack resistance of hard rock

Effect of surface-active substances on the crack resistance of hard rock

The effect of surface active substances on the electrochemical behaviour of copper ions in chloride solutions and in natural waters

Electrochemical methods have been used in the study of the adsorption behaviour of different surface active substances, biogenic and non-biogenic, as well as in the study of their complexation properties for copper ions in chloride solutions and in natural waters. The influence on the anodic oxidation wave of copper has been examined. For surface active substances (humic substances and proteins), which at the same time exhibit complexation properties towards copper ions, the main interaction will be complexation, especially in the lower concentration range of both copper and the organic substance. At higher concentrations of the surface active substances and copper ions adsorption effects may play a role in oxido-reduction processes of copper at the electrode surface covered with organic coating. Contrary to cadmium, the electrode reaction of copper is not greatly influenced by synthetic surface active substances like Triton X-100 and sodium dodecylsulphate, since in the potential range of the anodic wave of copper most synthetic surface actice substances are desorbed from the mercury electrode surface. In natural samples the main interaction will be complexation of copper ions with the organic matter. Investigations of the interfacial interactions between copper and organic coatings have to be continued on the other surfaces, natural and/or model ones, which have different surface properties and will be of greater environmental significance. Mercury electrode/solution interface is not a very convenient model for the study or interfacial interactions of copper ions because of the nature of the electrode process of copper.

The Polarographic Behaviour of Bromate Ions in Buffered and Unbuffered Solutions and the Effect of Surface Active Substances

AbstractThe polarographic behaviour of bromate ions in buffered and unbuffered solutions has been studied in the absence and presence of cationic, anionic and nonionic surfactants. The mechanism for the reduction in acid media is discussed. The adsorption effects of electrochemically inactive surfactants on the polarographic waves of BrO3− has been investigated. The values of the kinetic parameters for the electrode reaction at different pH values have been computed.

Adhesion Effects of Intermediate Layers on the Densification of Ceramic Powders

Abstract In the ceramic technology the first step to produce sintered bodies is the manufacturing of powders which then are densified. The adhesion mechanisms between the single particles and the agglomerates produced from them determine the densification process. Starting from theoretical considerations adhesion mechanisms, such as solid bridge formation, adhesive bonding and glide-promoting effects, are discussed in principle. Subsequently, the effects of surface-active substances on the densification behaviour of clay-ceramics and oxide-ceramic bodies are discussed. Further, the evaluation of the action of additives to the powder mixtures on the microstructure of the compacts, such as porsity and texture, leads to a compaction equation which describes the transition from the powder pile to a densified green body.

Effects of natural and synthetic surface active substances on the electrochemical reduction of cadmium in natural waters

Effects of surface active substances, natural and synthetic, in selected samples of seawater, river water and industrial effluents on the oxidation-reduction processes of cadmium have been studied by electrochemical methods and compared with the behaviour of different model compounds. Kinetic parameters, transfer coefficient α and apparent standard rate constant of the cadmium electrode reaction have been estimated from the shape and the height of the corresponding differential pulse voltammograms using theoretical curves obtained by digital simulation of the electrode process. The measure of the inhibition effect of surface active substances on the electrode reaction of cadmium was expressed in terms of the ratio of the rate constants determined in the presence and in the absence of surface active substances. It was found that the degree of inhibition depends on the concentration and type of surface active substances and on the pH of solution.

Effect of surface-active substances and of carbon disulfide in the viscose manufacturing precipitation bath on the chemical resistance of rubber materials

As a result of this study, it has been found that the effect of surface-active substances, solutions of sulfuric acid, or of a model precipitation bath on the chemical resistance of rubbers is slight.

Effect of surface-active substances on the synthesis of fibre-forming acrylonitrile copolymers

The effect of surface-active substances on the synthesis of fibre-forming acrylonitrile copolymers in aqueous sodium thiocyanate solutions has been studied. Increasing the content of surface-active substances in the reaction medium leads to a decrease in the overall activation energy of the copolymerization reaction and to a certain increase in the molecular weight of the copolymer.

Effect of surface-active substances on the viscosity of polyacrylonitrile spinning solutions

A content of surface-active substances of the type of berol'-visko-31 of up to 2.4% by wt. in a polyacrylonitrile spinning solution essentially does not affect its effective viscosity or “acting volume” at small shear stresses.

Effect of surface-active substances on the fibre-forming process and properties of nitron fibre

The effect of surface-active agents on the surface tension of polyacrylonitrile (PAN) spinning solutions has been studied.

Polarography of pyridine-2-carbaldehyde 2-pyridylhydrazone in solutions of varying pH at a dropping-mercury electrode: effect of surface-active substance

The polarographic behaviour of pyridine-2-carbaldehyde 2-pyridylhydrazone(PAPH) at a dropping-mercury electrode was studied in aqueous Britton–Robinson buffers containing 50% ethanol. The polarograms consist of one wave in the acidic and alkaline medium. Two electrons are consumed in the splitting of the N–N bond to give-2-aminopyridine and pyridine-2-carbaldehyde. The adsorption effects of cationic, anionic, and non-ionic surfactants on the polargraphic waves of PAPH have been investigated. The kinetic parameters for the electrode reaction at different pH values have been computed.

Effects of surface-active substances on gas holdup and gas-liquid mass transfer in bubble column.

The effects of surfactants and antifoam agent on the gas holdup ε, the liquid-phase mass transfer coefficient kL and the volumetric liquid-phase mass transfer coefficient kLa in a bubble column were studied experimentally. An addition of surfactants such as n-alcohols to water increases e and decreases kL, and an addition of antifoam agent to water decreases ε, kL and kLa. However, the degree of reduction of kL value by an addition of surfactant to water is lower for bubble swarms in a bubble column than that for a single bubble in stagnant liquid. Based on these observations, the previous model for estimating kL of a single bubble in aqueous solutions of surface-active substance is modified so as to be applicable to the estimation of kL for bubble swarms in a bubble column.

Catalytic Polarographic Wave of Fe(II) in Neutral Thiocyanate Solutions at Dropping Mercury Electrode

Abstract The electrochemical behavior of Fe(II) in neutral thiocyanate solutions has been investigated at a dropping mercury electrode (DME). It was found that Fe(II) in neutral thiocyanate solutions gave a catalytic polarographic wave at potentials prior to the main Fe(II) reduction wave. The mechanism of the catalytic process involves the chemical reduction of thiocyanate ions with Fe(OH)2,aq at the electrode surface. Controlled potential electrolysis suggests that the reduction of thiocyanate ions proceeds with the formation of sulfide and cyanide ions. Sulfide ions produced at the electrode surface can react with Fe(II) diffusing to the electrode to form FeS. The discharge of this is responsible for the catalytic current, while cyanide ions have no essential role in the catalytic process. The effects of surface active substances and iodate ions on the catalytic wave are also discussed.

Effect of surface-active substances on the formation of crosslinked polyurethanes

When using a number of methods to study kinetics and structural features of the formation of crosslinked polyurethanes in a system containing surface-active substances (SAS) it was found that the presence of the latter causes a marked change in reaction rate, the size of microheterogeneities formed during solidification, degrees of conversion at which crosslinked gel-formation begins and an polymer morphology. Results of investigations suggest that the effect of SAS on crosslinking is observed at the initial stage of gel-formation and involves the localization of SAS in the interfacial range, which separates microvolumes with a developed three-dimensional network from the overall reactions mass.

The polarographic behaviour of cinnamylidenebenzoichydrazide in solutions of varying ph at the dropping mercury electrode and the effect of surface active substances

AbstractThe polarographic behaviour of cinnamylidenebenzoichydrazide (CHB) in solutions of varying pH has been studied both in the absence and presence of cationic, anionic and nonionic surfactants. The mechanism for the reduction in alkaline and acid media is discussed. The adsorption effects of electrochemically inactive surfactants on the polarographic waves of CBH has been investigated. The values of the kinetic parameters for the electrode reaction at different pH values have been computed.

The effect of surface active substances on the overpotential components of the Pd-H 2 electrode

The effects of surface active substances on the overpotential components of the Pd-H 2 electrode in 1 N H 2SO 4 were examined by observing overpotential decay transients; the implications of the results for hydrogen absorption in palladium are discussed. Tetrabutylammonium ion and As 2O 3 mainly lowered the rate of the Volmer process. This should lead to a suppression of the hydrogen absorption into palladium at a given value of hydrogen overpotential. However, thiourea strongly retarded the Tafel process, and is therefore expected to increase the extent of hydrogen absorption. Na 2S and KI exerted an intermediate effect.

The Influence of Substances Reducing the Surface Energy of Naphthalene Single Crystals on Plastic Flow

Abstract The effect of surface active substances on plastic flow of naphthalene single crystals is considered. The role of normal and shear stresses is revealed. Rates of single crystals flow in different glide systems under constant stress are compared. The stress of plastic flow in single crystals can be decreased in active media by as much as 50%.

Study of the physiological effect of surface active substances

Study of the physiological effect of surface active substances

Effect of surface active substances on the polarographic catalytic hydrogen current of bovine serum albumin.

Effect of surface active substances on the polarographic catalytic hydrogen current of bovine serum albumin.

Katalytische Wirkung von Azobenzol in sauren Medien auf die Wasserstoffentwicklung an der tropfenden Quecksilberelektrode

Catalytic effect of azobenzene in acid media (pH<4.0) on hydrogen evolution at theDME is studied with special reference to its dependence on the H+ ion concentration in the solution. Comparison is made between the effect of strong and weak monobasic acids and polybasic acids on the catalytic current. The effect of surface active substances and the substituents is described.