Rational design of self-assembled surfactant film in nanopipettes: a combined fluorescence and electrochemical sensing

Herein, a generalizable method based on the formation of self-assembled surfactant film was reported to build a nanopipette system, which was applicable for both ionic current and fluorescent analysis of...

FULL-SCALE STUDIES OF FLUORESCENCE FEATURES OF SURFACTANT FILMS ON EUTROPHIC WATER WAVY SURFACE

The current paper presents the results of a full-scale study of the fluorescence features of pollutants ( diesel fuel, Urals oil), as well as an alcoholic solution of oleic acid, which imitates oil by visco-elastic characteristics. The experiment was carried out on the Gorky Reservoir under conditions of wind waves. Local areas of artificial slicks were created for multiple intersections at different angles to the wind and waves with continuous lidar sounding of the upper water layer. Signals were recorded by the ninth generation UVL-9 laser ultraviolet fluorescent lidar developed by the Institute of Oceanology of the Russian Academy of Sciences. At signal analysis, spectral intensities and fluorescence features of the studied substances are determined, possibilities of slick detecting as well as film thickness estimation are made, examples of surfactant film detecting behind the oleic slick where visual observation of pollutants does not give a result are showed. The obtained results are useful for the further development of fluorescent methods and devices for operational remote sensing of surface pollution on wave water surface.

Nanoparticle translocation across the lung surfactant film regulated by grafting polymers

Conditioning of grafting polymers, including their length, terminal charge, and grafting density, can result in different translocation processes of nanoparticles across the lung surfactant film.

Thermo-capillary flow in a Hele-Show cell as a tool for research of the dynamics of insoluble surfactant monolayer

The occurrence of thermocapillary convection in a Hele-Shaw cell in the presence of the surfactant film on the free surface is experimentally investigated. It is shown that at certain values of the control parameter two different zones are formed on the surface – the zone free from impurities and the stagnant zone. In the first zone, the onset and development of an intense Marangoni convection is observed, while in the stagnant zone the velocity of the motion on the surface is lower by about two orders of magnitude. This study clearly demonstrates that the analysis of the temperature profile provides sufficient information about both the distribution of tangential stresses over the surface and the degree of compression of the surfactant film. In addition, due to a simple linear law of temperature variation on the surface of the stagnant zone, the distribution of the surfactant molecules over the surface can be predicted based on the known equation of state for the film of the examined surfactant. Thus, the application of a set of simple experimental techniques to the examined model problem allowed us to obtain complete information on the state of a complex system consisting of a liquid layer and a surface film of the surfactant, the structure of the volumetric flow, the velocity of the liquid at the surface, the distribution of shear stresses and surfactant molecules over the surface.

Effects of magnetic fields on capillary-gravity waves in the presence of magnetic surfactants

The stability of capillary-gravity wave motion on horizontal free surface of viscous noncompressible fluid in the presence of magnetic surfactant in an external magnetic field was studied. It is shown that for normal as well as for tangential external magnetic field the horizontal free liquid surface is unstable for field strength exceeding some critical value that does not depend on the elastic constant of the surfactant film. However, for oblique external magnetic field the stability of the free surface depends not only on the field value but also on the surfactant elastic constant.

Synergistic Interaction in the adsorbed mixed surfactants film of Sodium Dodecyl Sulfate and Cocamidopropyl Betaine on Liquid – Air Interfacial

In the present work, the critical micelle concentration (CMC) of the solution of Sodium dodecyl sulfate (SDS) as anionic surfactant, Cocamidopropyl Betaine (CAPB) as amphoteric surfactant, and their mixture have been determined using surface tension and conductivity measurements at a temperature range 293 -323 K. The adsorption and thermodynamic micellization parameters (?G?m, ?G?ads, ?max ,Amin,?cmc ) for individual surfactants was calculated. Rosen model which is focuses on the adsorbed mixed surfactant film at the air/solution interface was used to calculate the interaction parameter ( ?? ) at the interface and the activity coefficients g1 and g2. The results indicate that the CMC of the individual surfactants was affected by the temperature at the temperature range studied. Also, the results indicate a synergistic effect present at the air – solution mixed film of surfactants.

Silver nanoparticles/polyethyleneimine/graphene oxide composite combined with surfactant film for construction of an electrochemical biosensor

The combination of silver nanoparticles/polyethyleneimine/graphene oxide composite and surfactant film for investigating direct electrochemistry and electrocatalysis of hemoglobin.