Article

1998 ◽  
Vol 76 (2) ◽  
pp. 152-157
Author(s):  
Catherine E Drennan ◽  
Rachelle J Hughes ◽  
Vincent C Reinsborough ◽  
Oladega O Soriyan

Kinetic studies through stopped-flow spectroscopy were undertaken in the dilute solution range of anionic surfactants where pronounced rate enhancement or inhibition of Ni2+-ligand complexations is often observed at surfactant concentrations much below the critical micelle concentration (CMC). The results are interpreted in terms of Ni-surfactant micelles as the agents responsible for the rate changes in dilute surfactant solution. At higher surfactant concentrations these micelles are transformed into mixed micelles (counterion and size changes), eventually becoming normal surfactant micelles close to the CMC. Surface tension, dye solubility, conductivity, and fluorescent probe investigations support this interpretation.Key words: micellar catalysis, sodium dodecyl sulfate, micelles, critical micelle concentration, premicelles, Ni2+-ligand complexations.

1991 ◽  
Vol 56 (4) ◽  
pp. 785-795 ◽  
Author(s):  
Jiří Bílý ◽  
Ludmila Čermáková ◽  
Jiří Knapp

The values of the apparent dissociation constants of the azo dye 4-(2-pyridylazo)-resorcinol (PAR) have been found in the presence of sub- and supercritical concentrations of the anionogenic tenside sodium dodecyl sulphate (SDS) and the effects of the strong electrolytes NaCl and NaNO3 were also evaluated. In both electrolytes, the pKan values initially are independent of the SDS concentration and then increase. Spectrophotometric and surface tension measurements were employed to determine the critical micelle concentration (cmc) of SDS alone and in the presence of PAR and the given electrolytes. The determined cmc values were in the range 0.20–3.02 mmol l-1 and dependent on the type and concentration of the particular additive.


Coatings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 143 ◽  
Author(s):  
Phillip Johnson ◽  
Mauro Vaccaro ◽  
Victor Starov ◽  
Anna Trybala

Foams are a common occurrence in many industries and many of these applications require the foam to interact with porous materials. For the first time interaction of foams with porous media has been investigated both experimentally and theoretically by O. Arjmandi-Tash et al. It was found that there are three different regimes of the drainage process for foams in contact with porous media: rapid, intermediate and slow imbibition. Foam formation using soft porous media has only been investigated recently, the foam was made using a compression device with soft porous media containing surfactant solution. During the investigation, it was found that the maximum amount of foam is produced when the concentration of the foaming agent (dishwashing surfactant) is in the range of 60–80% m/m. The amount of foam produced was independent of the pore size of the media in the investigated range of pore sizes. This study is expanded using sodium dodecyl sulphate (SDS), which has the same critical micelle concentration as the commercial dishwashing surfactant, where the foam is formed using the same porous media and compression device. During the investigation, it was found that 10 times the critical micelle concentration (CMC) is the optimum concentration for a pure SDS surfactant solution to create foam. Any further increase in concentration after that point resulted in no further mass of foam being generated.


Author(s):  
Zh.B. Ospanova ◽  
S. Toktagul ◽  
A. Tasmagambetova ◽  
M. Asadov

The results of the study of foams stabilized by solid coal particles are given. The method of sedimentation analysis determined the most likely radius of coal particles equal to 20.28 microns. Foaming ability was determined by the height of the foam column obtained by the method of bubbling within 1 min. Foam stability was determined by the time of complete destruction of the foam column. Foams stabilized by the compositions of anionic surfactants – sodium dodecyl sulfate (DDSNa) and sulfonol (SF) with polyvinyl alcohol (PVA) in the presence of hydrophobic solid particles of coal showed greater foaming capacity and stability compared to foams from individual surfactants. The surface tension isotherms of aqueous solutions of surfactants, PVA, and their mixtures were obtained. An increase in the stability of foams in the presence of coal particles corresponds to a decrease in the surface tension at the liquid-gas interface. The stability of foams obtained from surfactant-PVA compositions is explained by the combined influence of thermodynamic (reduction of surface tension) and structural-mechanical (increase in viscosity of inter-membrane fluid) of stability factors. These properties of foams can be used to suppress dust in coal mining.


2021 ◽  
Vol 19 (4) ◽  
pp. 20-26
Author(s):  
Inaam H. Ali ◽  
Sameer H. Kareem ◽  
Fouad A.A. AL-Saady

In the current work, we discuss the mixed micelles and thermodynamic micellization of aqueous binary mixture of polyoxyethylene - 20 sorbitan-monododecanoate (Tween 20) as nonionic surfactant and Benzyldimethylhexadecyl ammonium chloride (HDBAC) as cationic surfactant using conductivity and surface tension (γ) estimations in the temperatures range (288 -318K). Critical micelle concentration (CMC) and variables of micellization, like the standard thermodynamic functions: Gibbs free energy (Δ𝐺𝑚 ⁰ ), enthalpyΔ𝐻𝑚 ⁰ ) and entropy (Δ𝑆𝑚 ⁰ ) were calculated using the variation of conductivity and γ with molar concentration and the variation of ln XCMC with temperature. The experimental CMC values were applied to calculate the mole fractions of surfactant in the mixed micelle (𝑋1 𝑚 ), the β parameter and the coefficient of activity f1and f2, using the equations proposed by Clint and Rubingh, which indicate the β parameter, is always negative. In addition, the results of thermodynamic parameters show that ΔG⁰m are negative for both individual and mixture of HDBAC-Tween20 surfactants and the values negatively increased with increasing temperature while its negative values decreasing with decreasing initial mole fraction of HDBAC.


2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Jelena Cvejić ◽  
Mihalj Poša ◽  
Ana Sebenji ◽  
Milica Atanacković

In this study we investigated resveratrol (trans-3,5,4′-trihydroxystilbene) solubilization with sodium 3α,12α-dihydroxy-7-oxo-5β-cholanoate (S7-OD) and sodium dodecyl sulfate (SDS). The investigation was aimed at determining whether large spherical micelles (SDS) or small longitudinal micelles (S7-OD) are more convenient for incorporation of resveratrol. Also, we studied resveratrol behavior in mixed micelles with mentioned surfactants using spectroflourimetric method as well as the effects of sodium chloride and urea on resveratrol solubilization capacity in the applied surfactants. Resveratrol solubilization curve was different in the investigated surfactants. Resveratrol solubilization curve for sodium 3α,12α-dihydroxy-7-oxo-5β-cholanoate at concentration 0.9 CMC reached saturation level of 60% dissolved resveratrol. The curve for sodium dodecyl sulfate was linear within the whole range of the investigated concentration; resveratrol solubilization rate reached 13% at 2 CMC. In S7-OD, NaCl increased capacity of resveratrol solubilization up to 1.4 CMC surfactant concentration, whilst maximum level of dissolved resveratrol (90%) was observed at 0.9 CMC. In SDS, NaCl decreased resveratrol solubilization capacity. Urea reduced resveratrol solubilization rate in sodium 3α,12α-dihydroxy-7-oxo-5β-cholanoate, whereas it had inverse effect in sodium dodecyl sulfate. The obtained results strongly suggest that structure, that is, shape, of the surfactant micelles significantly affects their capacity of resveratrol solubilization. Also, presence of NaCl and urea influences solubilization capacities of investigated surfactants.


BIBECHANA ◽  
2014 ◽  
Vol 11 ◽  
pp. 79-85 ◽  
Author(s):  
Kuber Limbu ◽  
Sujit Kumar Shah ◽  
Ajaya Bhattarai

The accurate measurements of surface tension of sodium dodecyl sulphate (SDS) in distilled water and in presence of 0.01M Na2SO4 and 0.01M ZnSO4 at room temperature were reported by drop weight method using a stalagmometer. The critical micelle concentration (cmc) of sodium dodecyl sulphate (SDS) in distilled water was obtained higher than in presence of Na2SO4 and ZnSO4. The decrease of cmc of sodium dodecyl sulphate in the presence of salts has been discussed. DOI: http://dx.doi.org/10.3126/bibechana.v11i0.10383 BIBECHANA 11(1) (2014) 79-85


2020 ◽  
Vol 17 (1(Suppl.)) ◽  
pp. 0305
Author(s):  
Sammer Hakeem

In the present work, the surface properties of mixed binary surfactants containing sodium dodecylbenzene sulfate (SDBS) and Tween 80 (TW80) surfactants in aqueous solutions were studied at temperature 293 K using surface tension measurements. The critical micelle concentration (cmc) magnitude for both individual surfactants and their mixtures were established the obtained results revealed  that the magnitude of cmc of the mixtures are less than the magnitude of individual surfactants and decrease with the increase in Tween 80 percent in solution which indicate the nonideal  mixing of the two surfactants. The values of molecular interaction parameters  and the mole fraction of surfactants in the micelle (X1) were calculated on the basis of Rubingh’s model and showed that the interaction parameter is always negative but at 0.9 mole fraction of TW80 surfactant (α1) is positive


BIBECHANA ◽  
2014 ◽  
Vol 11 ◽  
pp. 103-112 ◽  
Author(s):  
Tulasi Prasad Niraula ◽  
Ajaya Bhattarai ◽  
Sujeet Kumar Chatterjee

Careful measurements of surface tension and viscosity of sodium dodecyl sulphate (SDS) in presence and absence of KCl in pure water and methanol-water mixed solvent media containing 0.1, 0.2, 0.3 and 0.4 volume fractions of methanol at 308.15 K are reported. The concentration of KCl is 0.01M. The concentration of SDS varies from 4.86×10-3 to 29.56×10-3 mol.l-1. The critical micelle concentration (cmc) increases with increase in percentage of methanol and decreases with addition of salt. DOI: http://dx.doi.org/10.3126/bibechana.v11i0.10388 BIBECHANA 11(1) (2014) 103-112


Sign in / Sign up

Export Citation Format

Share Document