scholarly journals Adsorption of Polycomplexes at Solution/Air Interface

2017 ◽  
Vol 4 (4) ◽  
pp. 259
Author(s):  
E.M. Shaikhutdinov ◽  
K.Zh. Abdiyev ◽  
M.B. Zhursumbayeva ◽  
S.Kh. Khussain
Keyword(s):  
Surface Tension ◽  
Relaxation Time ◽  
Complex Formation ◽  
Surface Activity ◽  
Kinetic Data ◽  
Hydrophobic Interactions ◽  
Standard Free Energy ◽  
Free Energy Of Adsorption ◽  
Air Interface ◽  
Potentiometric Measurements

<p>The effect of complex formation of polyacids (polyacrylic (PAAc) and polymethacrylic (PMAAc)) with polyacrylamide (PAA) on their surface properties at solution/air interface has been studied by surface tension, electric conductivity and potentiometric measurements at 293±0.2 K. The relaxation time and surface activity of polycomplexes were calculated from kinetic data on the surface tension. It was found that during complex formation the relaxation time of a surface layer has a maximum and the surface activity of macromolecules is increased. Also the standard free energy of adsorption for PAA and polyacid-PAA polycomplexes were calculated. They are equal DadsG°<sub>293</sub> = - 19.1±0.1 kJ/base-mol. for PAA, DadsG°<sub>293</sub> = -21.2±0.1 kJ/basemol. for PMAAc-PAA polycomplex and DadsG°<sub>293</sub> = -23.0±0.1 kJ/base-mol. for PAAc-PAA polycomplex (calculation per base-mole of PAA monomer link). It is shown that the surface activity and ability to decrease of the water surface tension is less for PMAAc-PAA than for PAAc-PAA. Such anomalous behaviour of PMAAc-PAA polycomplex probably is caused by an excessive strengthening of inner- and intermolecular hydrophobic interactions in macromolecules of PMAAc- PAA polycomplexes due to the presence of α-methyl groups in PMAAc macromolecules. Because of the rebuilding of macromolecule segments of complex by polarity at the interface is becoming a difficult one.</p>

scholarly journals Adsorption Properties of Hydrocarbon and Fluorocarbon Surfactants Ternary Mixture at the Water-Air Interface

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4313
Author(s):  
Bronisław Jańczuk ◽  
Katarzyna Szymczyk ◽  
Anna Zdziennicka
Keyword(s):  
Surface Tension ◽  
Water Surface ◽  
Standard Free Energy ◽  
Ternary Mixtures ◽  
Free Energy Of Adsorption ◽  
Interface Tension ◽  
Air Interface ◽  
Surface Excess Concentration ◽  
Tail Water ◽  
Triton X

Measurements were made of the surface tension of the aqueous solutions of p-(1,1,3,3-tetramethylbutyl) phenoxypoly(ethylene glycols) having 10 oxyethylene groups in the molecule (Triton X-100, TX100) and cetyltrimethylammonium bromide (CTAB) with Zonyl FSN-100 (FC6EO14, FC1) as well as with Zonyl FSO-100 (FC5EO10, FC2) ternary mixtures. The obtained results were compared to those provided by the Fainerman and Miller equation and to the values of the solution surface tension calculated, based on the contribution of a particular surfactant in the mixture to the reduction of water surface tension. The changes of the aqueous solution ternary surfactants mixture surface tension at the constant concentration of TX100 and CTAB mixture at which the water surface tension was reduced to 60 and 50 mN/m as a function of fluorocarbon surfactant concentration, were considered with regard to the composition of the mixed monolayer at the water-air interface. Next, this composition was applied for the calculation of the concentration of the particular surfactants in the monolayer using the Frumkin equation. On the other hand, the Gibbs surface excess concentration was determined only for the fluorocarbon surfactants. The tendency of the particular surfactants to adsorb at the water-air interface was discussed, based on the Gibbs standard free energy of adsorption which was determined using different methods. This energy was also deduced, based on the surfactant tail surface tension and tail-water interface tension.

scholarly journals Comparison between surface and volumetric properties of short-chain alcohols and some classical surfactants

2016 ◽  
Vol 71 (1) ◽  
pp. 1 ◽  
Author(s):  
Magdalena Bielawska ◽  
Anna Zdziennicka ◽  
Bronisław Jańczuk
Keyword(s):  
Free Energy ◽  
Aqueous Solutions ◽  
Chemical Potential ◽  
Standard Free Energy ◽  
Dynamic Surface Tension ◽  
Short Chain ◽  
Critical Aggregation Concentration ◽  
Free Energy Of Adsorption ◽  
Dynamic Surface ◽  
Air Interface

<p>Measurements of the dynamic surface tension of the aqueous solutions of methanol, ethanol, propanol, CTAB and SDDS at their given concentrations were made. From the obtained results and the literature data it was concluded that the adsorption of short-chain alcohols at the water-air interface is somewhat similar to that of classical surfactants. For that reason the relationship between the Gibbs standard free energy of adsorption of short-chain alcohols and classical surfactants at that interface was established. The correlation between the chemical potential of mixing of alcohols and surfactants was also analysed. This analysis concerned the critical aggregation concentration (CAC) of alcohols and the critical micelle concentration (CMC) of surfactants. The chemical potential of surfactant mixing was calculated from the literature CMC data for the homologous series of alkyl sulfates, alkyl sulfonates, alkyl ammonium chlorides, alkyl trimethylammonium bromides, and alkyl pyridinium bromides. The influence of the hydrophobic chain length of alcohol and surfactant molecules on the Gibbs standard free energy of their adsorption at the water-air interface and their chemical potential of mixing were considered. It appeared that there is a linear dependence between these thermodynamic functions and the number of carbon atoms increased by 1 in the hydrocarbon chains of these compounds. This confirms clearly our conclusion that the behaviour of short-chain alcohols and classical surfactants at the water-air interface and in the bulk phase of aqueous solutions is similar. </p>

scholarly journals Experimental Investigations of Behaviour of Biosurfactants in Brine Solutions Relevant to Hydrocarbon Reservoirs

2019 ◽  
Vol 3 (1) ◽  
pp. 24 ◽  
Author(s):  
Tinuola Udoh ◽  
Jan Vinogradov
Keyword(s):  
Surface Tension ◽  
Free Energy ◽  
Oil Recovery ◽  
High Salinity ◽  
Standard Free Energy ◽  
Experimental Investigations ◽  
Surface Excess ◽  
Hydrocarbon Reservoir ◽  
Air Interface ◽  
Gibbs Surface Excess

In this study, we investigated the behaviour of rhamnolipid and Greenzyme in brine solutions relevant to hydrocarbon reservoir. Prior to this work, several studies only reported the behaviour of the biosurfactants dissolved in sodium chloride solutions of varied salinity. The results of this study are relevant to the application of the biosurfactants in enhanced oil recovery, during which the compounds are injected into reservoir saturated with formation water, typically of high salinity and complex composition. Surface tension and conductivity methods were used to determine the critical micelle concentrations of the biosurfactants, Gibbs surface excess concentrations and standard free energy at water-air interface. The results show that rhamnolipid and Greenzyme could reduce the surface tension of water from 72.1 ± 0.2 mN/m to 34.7 ± 0.4 mN/m and 47.1 ± 0.1 mN/m respectively. They were also found to be stable in high salinity and high temperature with rhamnolipid being sensitive to brine salinity, composition and pH while Greenzyme showed tolerance for high salinity. Furthermore, the Gibbs standard free energy of micellisation shows that rhamnolipid and Greenzyme have the tendency to spontaneously form micelles with rhamnolipid showing more surface adsorption. However from maximal Gibbs surface excess concentration calculations, Greenzyme monomers tend to favour aggregation more than that of rhamnolipid.

Dynamic surface tension of xylem sap at the air-water interface

2021 ◽  
Author(s):  
Reddy Prasanna Duggireddy ◽  
Eran Raveh ◽  
Gilboa Arye
Keyword(s):  
Surface Tension ◽  
Surface Activity ◽  
Pure Water ◽  
Xylem Sap ◽  
Dynamic Surface Tension ◽  
Bulk Solution ◽  
Diffusion Control ◽  
Dynamic Surface ◽  
Equilibrium Surface Tension ◽  
Air Interface

&lt;p&gt;The surface tension (ST) of xylem sap at the water-air interface is a crucial phenomenon, influencing many physiological events such as air seeding and embolism, by which xylem vessels become air-filled and cease to function. Refilling of embolized, may relies on sap&amp;#8217;s surface activity at the interface. It is commonly assumed that the ST of xylem sap is equal to the ST of pure water (72 mN/m). However, xylem sap is a complex solution and consists of surface-active molecules that may adsorb and accumulate at the water-air interface and thereby reduce the ST of water as a function of their aqueous concentration. However, when a new water-air interface is formed, equilibrium ST is not reached instantaneously. Specifically, amphiphilic molecules are kinetically adsorbed and undergo orientation at the interface following diffusion from the bulk solution. Dynamic ST of xylem sap and liquid-solid interactions, describing the surface phenomena of the xylem of vascular plants is currently not fully understood. This is mainly due to a lack of quantitative knowledge on the rate and extent of dynamic and equilibrium ST of sap. In this regard, the main objective of this study is to quantify the dynamic and equilibrium ST of xylem sap as a function of their aqueous concentration. We extracted xylem sap from lemon trees and measured ST as a function of time using the pendant drop technique. The dynamic ST data were analyzed using empirical and diffusion-control mathematical models which adequately described the exponential-like decay of the ST as a function of time. The results showed reduced ST of water in the xylem sap, indicating significant surface activity, reaching equilibrium ST values as low as 42 mN/m. The rate of ST decay was higher in high sap concentration and reduced in diluted one. The results of dynamic and equilibrium ST and the corresponding model will be presented and their implications for xylem hydraulic functioning will be discussed.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Keywords: Dynamic surface tension, Equilibrium surface tension, Diffusion, Xylem sap.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals Surface - Active and Complexforming Copolymers of Sodium 2-acrylamido-2-methylpropanesulfonate with Ethyleneglycol Vinyl Ether

2015 ◽  
Vol 15 (4) ◽  
pp. 313
Author(s):  
Y.M. Shaikhutdinov ◽  
S.Kh. Khussain ◽  
N.Zh. Seitkaliyeva ◽  
A.Zh. Zhenissova ◽  
Z.G. Akkulova
Keyword(s):  
Surface Tension ◽  
Free Energy ◽  
Ethylene Glycol ◽  
Vinyl Ether ◽  
Surface Activity ◽  
Water Solution ◽  
Molar Fraction ◽  
Standard Free Energy ◽  
Water Soluble ◽  
Interpolymer Complex

<p>A new water-soluble polyelectrolyte - the copolymer of sodium 2-acrylamido-2-methylpropanesulfonate and ethylene glycol vinyl ether has been synthesized by free-radical copolymerization in aqueous medium. Synthesis of the linear structure water-soluble copolymer of sodium 2-acrylamido-2-methylpropanesulfonate (Na-AMPS) and ethylene glycol vinyl ether (EGVE) has been confirmed by IR spectroscopy method, potentiometric titration and viscometer. The concentration behavior of the reduced viscosity of copolymer solutions that is typical for polyelectrolytes has been revealed. The reactivity ratios for the copolymerization of the monomers estimated by the Mayo–Lewis method have indicated lower reactivity of ethylenglycol vinyl ether in comparison with sodium 2-acrylamido-2-methylpropanesulfonate. Also it was shown the decrease of reaction’s relative rate with an increase of molar fraction of EGVE in the initial mixture of monomers. Adsorption at the air-water solution interface was studied by measure of surface tension (σ) in order to determine the surface properties of new copolymers of ethyleneglycol vinyl ethers – sodium 2-acrylamido-2-methylpropanesulfonate. It was shown that copolymers of sodium 2-acrylamido-2-methylpropanesulfonate and ethylenglycol vinyl ether have higher surface activity compared to sodium 2-acrylamido-2-methylpropanesulfonate homopolymer. The isotherm of copolymer’s surface tension based on equilibrium value of σ was constructed together with the isotherm of surface tension water solution poly- Na-AMPS. Based on isotherms the surface activity on Rebinder (G<sub>Re</sub>) for poly- Na-AMPS and copolymer Na-AMPS-EGVE was determined. The values of polymer’s standard free energy of adsorption (Δ<sub>ads</sub>G<sup>0</sup><sub>298</sub>) were calculated in order to identify the causes and mechanism of change in surface activity and adsorption. Results show that the gain in standard free energy adsorption in the transition from homopolymer to copolymer Na-AMPS-EGVE is about 4 kJ/base-mole. Interpolymer reaction of the Na-AMS–EGVE copolymer with poly- <em>N,N</em>-dimethyl-<em>N,N</em>-diallylammonium chloride (PMAAC) has been studied. Higher surface activity of mixtures of copolymer and PMAAC than of individual polyelectrolytes was discovered. This effect testified to the formation of interpolymer complex of the Na-AMS–EGVE copolymer with polycations due to electrostatic interactions.</p>

scholarly journals Surface Activity of Humic Acid and Its Sub-Fractions from Forest Soil

2021 ◽  
Vol 13 (15) ◽  
pp. 8122
Author(s):  
Shijie Tian ◽  
Weiqiang Tan ◽  
Xinyuan Wang ◽  
Tingting Li ◽  
Fanhao Song ◽  
...  
Keyword(s):  
Surface Tension ◽  
Particle Size ◽  
Humic Acid ◽  
Forest Soil ◽  
Surface Activity ◽  
Self Assembly ◽  
Average Particle Size ◽  
Gaussian Model ◽  
Exponential Model ◽  
Average Particle

Surface activity of humic acid (HA) and its six sub-fractions isolated from forest soil were characterized by surface tension measurements, dynamic light scattering, and laser doppler electrophoresis. The surface tension of HA and its sub-fractions reduced from 72.4 mN·m−1 to 36.8 mN·m−1 in exponential model with the increasing concentration from 0 to 2000 mg·L−1. The critical micelle concentration (CMC) and Z-average particle size ranged from 216–1024 mg·L−1 and 108.2–186.9 nm for HA and its sub-fractions, respectively. The CMC have related with alkyl C, O-alkyl C, aromatic C, and carbonyl C (p < 0.05), respectively, and could be predicted with the multiple linear regression equation of CMC, CMC = 18896 − 6.9 × C-296 × alkyl C-331 × aromatic C-17019 × H/C + 4054 × HB/HI (p < 0.05). The maximum particle size was 5000 nm after filtered by a membrane with pore size of 450 nm, indicating HA and its sub-fractions could progressed self-assembly at pH 6.86. The aggregate sizes of number-base particle size distributions were mainly in six clusters including 2 ± 1 nm, 5 ± 2 nm, 10 ± 3 nm, 21 ± 8 nm, 40 ± 10 nm, and >50 nm analyzed by Gaussian model that maybe due to the inconsistency of the components and structures of the HA sub-fractions, requiring further study. It is significance to explore the surface activity of HA and its sub-fractions, which is helpful to clarify the environmental behavior of HA.

The Chorionic Plastron and its Role in the Eggs of the Muscinae (Diptera)

1960 ◽  
Vol s3-101 (55) ◽  
pp. 313-332
Author(s):  
H. E. HINTON
Keyword(s):  
Surface Tension ◽  
High Pressures ◽  
Middle Layer ◽  
Clean Water ◽  
Active Materials ◽  
Great Resistance ◽  
Plane Normal ◽  
Air Interface ◽  
Surface Active ◽  
Egg Shell

In flies of the subfamily Muscinae the egg-shell has both an outer and an inner meshwork layer, each of which holds a continuous film of air. Between these two meshwork layers there is a more or less thick middle layer to which the shell chiefly owes its mechanical strength. Holes or aeropyles through the middle layer effect the continuity of the outer and inner films of air. Both meshwork layers consist of struts that arise perpendicularly from the middle layer. In both layers the struts are branched at their apices in a plane normal to their long axes. These horizontal branches form a fine and open hydrofuge network that provides a large water-air interface when the egg is immersed. When it rains or when the egg is otherwise immersed in water, the film of air held in the outer meshwork layer of the shell funtions as a plastron. To be an efficient respiratory structure a plastron must resist wetting by both the hydrostatic pressures and the surface active materials to which it is normally exposed. The plastrons of all the Muscinae tested resist wetting in clean water by pressures far in excess of any they are likely to encounter in nature. The resistance of a plastron to hydrostatic pressures varies directly as the surface tension of the water, and the surface tension of water in contact with the decomposing materials in which the Muscinae lay their eggs is much lowered by surface active materials. These considerations seem to provide an explanation for the great resistance of the plastron of the Muscinae to wetting by excess pressures and for the paradox that the plastrons of these terrestrial eggs are more resistant to high pressures than are the plastrons of some aquatic insects that live in clean water.

scholarly journals Properties of the seawater-air interface. Dynamic surface tension studies1

1979 ◽  
Vol 24 (6) ◽  
pp. 1022-1030 ◽  
Author(s):  
Dj. Dragcevic ◽  
M. Vukovic ◽  
D. Cukman ◽  
V. Pravdic
Keyword(s):  
Surface Tension ◽  
Dynamic Surface Tension ◽  
Dynamic Surface ◽  
Air Interface ◽  
Interface Dynamic

Surface Activity Research of Cationic Gemini Surfactants

2013 ◽  
Vol 690-693 ◽  
pp. 2076-2080
Author(s):  
Zhen Zhong Fan ◽  
Lan Lan Li ◽  
Li Feng Zhang ◽  
Qing Wang Liu
Keyword(s):  
Surface Tension ◽  
Critical Micelle Concentration ◽  
Surface Activity ◽  
Surfactant Concentration ◽  
Gemini Surfactant ◽  
Gemini Surfactants ◽  
Ph Value ◽  
Inorganic Salts ◽  
Cationic Gemini Surfactant ◽  
Cationic Gemini Surfactants

Cationic Gemini surfactant concentration, the inorganic salts added and the pH value of surface tension obtained cationic gemini surfactant critical micelle concentration is 0.4mmol / L;by adding three kinds of inorganic salts NaCl, MgCl2, and Na2SO4 ,which Na2SO4 has the greatest impact on surface tension, followed by MgCl2.The surface minimum tension of the pH ranged from 9 to 11 , indicating that the surface activity of cationic gemini surfactants achieved the highest.

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