Micellar rate enhancement studies in mixed sodium fluorocarbon/hydrocarbon surfactant solutions

1992 ◽  
Vol 70 (6) ◽  
pp. 1581-1585 ◽  
Author(s):  
Terrence J. Connolly ◽  
Vincent C. Reinsborough
Keyword(s):  
Mixed Micelles ◽  
Anionic Surfactants ◽  
Binding Constants ◽  
Kinetic Studies ◽  
Bulk Solution ◽  
Reaction Volume ◽  
Sodium Decylsulfate ◽  
The Difference ◽  
Anionic Micelles ◽  
Robinson Equation

Stopped-flow kinetic studies were conducted in mixed micellar solutions of fluorocarbon and hydrocarbon anionic surfactants to determine the prevalent micellar form. The probe reaction was the Niaq2+/pyridine-2-azo-p-dimethylaniline (PADA) complexation, which is many times accelerated in the presence of anionic micelles. Binding constants for Niaq2+ and PADA partitioning between bulk solution and micelles were determined through the murexide technique and solubility measurements respectively and the molar reaction volume was obtained from the Robinson equation. The three binary surfactant systems investigated had sodium perfluoroheptanoate as the fluorocarbon surfactant while the hydrocarbon surfactants were sodium decylsulfate, sodium nonanesulfonate, and sodium octanesulfonate. The kinetic results were consistent with unimicellar composition in all three systems which was not the behaviour previously found with the sodium octane sulfonate/sodium perfluoroctanoate system. The difference was attributed to closer similarity in the surfactant pair hydrophobicities as revealed through their critical micelle concentrations. Another finding was that mixed micelles synergistically can lead to a much greater solubilization of PADA than is possible through either of the pure surfactants.

Rate Enhancement of Nickel(II)-pada Complex-Formation in Mixed Sodium Perfluorooctanoate/Octanesulfonate Micellar Solutions

1990 ◽  
Vol 43 (1) ◽  
pp. 11 ◽  
Author(s):  
VC Reinsborough ◽  
TDM Stulz ◽  
XY Xiang
Keyword(s):  
Binding Constants ◽  
Kinetic Studies ◽  
Bidentate Ligand ◽  
Bulk Solution ◽  
Complexation Reaction ◽  
Reaction Volume ◽  
Rate Enhancement ◽  
Maximum Value ◽  
Sodium Perfluorooctanoate ◽  
Robinson Equation

Kinetic studies of the Niaq2+ ion complexation with the bidentate ligand pyridine-2-azo-p-dimethylaniline ( pada ) were conducted by the stopped-flow technique in the presence of mixed micelles of sodium perfluorooctanoate ( spfo ) and sodium octanesulfonate ( sos ). Binding constants for Niaq2+ and pada partitioning between bulk solution and micelles were determined through solubility measurements and the murexide techniques respectively. The molar reaction volume for the surfactant was obtained through the fitting of the kinetic data and partitioning constants to the Robinson equation. It was found that spfo micelles promoted the complexation reaction 400-fold just beyond the critical micelle concentration but this maximum value decreased with sos , NaCl or further spfo addition. The unexpected effectiveness of spfo in rate enhancement is due to its compact micellar reaction volume of 0.16 dm3 mol-1. The kinetic results are consistent with spfo and sos forming separate micelles of pure or almost pure composition.

Article

1998 ◽  
Vol 76 (2) ◽  
pp. 152-157
Author(s):  
Catherine E Drennan ◽  
Rachelle J Hughes ◽  
Vincent C Reinsborough ◽  
Oladega O Soriyan
Keyword(s):  
Surface Tension ◽  
Critical Micelle Concentration ◽  
Mixed Micelles ◽  
Anionic Surfactants ◽  
Sodium Dodecyl ◽  
Surfactant Solution ◽  
Kinetic Studies ◽  
Stopped Flow ◽  
Dilute Solution ◽  
Surfactant Micelles

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.

Rate enhancements for the nickel(II)–PADA complexation in mixed anionic micelles

1983 ◽  
Vol 61 (7) ◽  
pp. 1594-1597 ◽  
Author(s):  
Paul D. I. Fletcher ◽  
Joanne R. Hicks ◽  
Vincent C. Reinsborough
Keyword(s):  
Kinetic Analysis ◽  
Mixed Micelle ◽  
Mixed Micelles ◽  
Sodium Dodecylsulfate ◽  
Electrostatic Forces ◽  
Rate Enhancement ◽  
The Third ◽  
Micellar Systems ◽  
Sodium Decylsulfate ◽  
Anionic Micelles

Rate enhancements for the [Formula: see text] and pyridine-2-azo-p-dimethylaniline (PADA) reaction have been obtained in four simple equimolar binary micellar systems: sodium dodecylsulfate – sodium decylsulfate, sodium dodecylsulfate – sodium octylsulfate, sodium octylsulfate – sodium hexylsulfate, and sodium octylsulfate – sodium octanesulfonate. The rate enhancement curves were similar to those obtained for pure surfactants and were consistent with a 1:1 mixed micelle except for the third system where the micelle was richer in sodium octylsulfate. The kinetic analysis revealed no dramatic changes in hydrophobic or electrostatic forces on forming the mixed micelles

scholarly journals Molecular Interactions in Binary Surfactant Solutions: Effect of pH

2019 ◽  
Vol 64 (4) ◽  
pp. 437-445
Author(s):  
Olga Kochkodan ◽  
Victor Maksin ◽  
Nadiya Antraptseva ◽  
Tetyana Semenenko
Keyword(s):  
Molecular Interactions ◽  
Mixed Micelles ◽  
Ph Value ◽  
Chemical Properties ◽  
Micelle Formation ◽  
Bulk Solution ◽  
Surfactant Mixtures ◽  
Solution Ph ◽  
Solution Interface ◽  
Adsorption Layers

By using surface tension and conductivity measurements, the colloid-chemical properties of the mixtures of cationic hexadecylpyridinium bromide with nonionic Triton X-100 surfactants were investigated both in the bulk solution and at air/solution interface at different pH values. The composition of mixed micelles and adsorption layers, parameters of molecular interactions in mixed micelles βm and adsorption layers βσ, as well as standard free energies of micelle formation ΔG0mic and adsorption ΔG0ads were calculated. It was found that molecules of the nonionic surfactant presumably dominate in the mixed micelles and adsorption layers. It was shown that βm and βσ have negative values, which indicate the strengthening of intermolecular interactions in the mixed micelles and adsorption layers. Based on the data obtained, it was suggested that ion-dipole interactions are involved in the formation of intermolecular structures between nonionic and cationic surfactants in aqueous solution and at the air-solution interface. It was shown that βm, βσ as well as ΔG0mic and ΔG0ads parameter depends on the solution pH value. The complex interplay of ion-dipole, protonation and chelation processes, which occur in the surfactant mixtures at different pH and affect the strength of intermolecular interaction, should be taken into account for data analysis.

scholarly journals Effect of Cationic/Anionic Mixed Micelles on Reaction Kinetics of Alkaline Hydrolysis of Crystal Violet

2019 ◽  
Vol 31 (3) ◽  
pp. 651-655
Author(s):  
Qidist Yilma ◽  
Dunkana Negussa ◽  
Y. Dominic Ravichandran
Keyword(s):  
Crystal Violet ◽  
Alkaline Hydrolysis ◽  
Mixed Micelles ◽  
Sodium Dodecyl ◽  
Binding Constants ◽  
Regression Parameters ◽  
Experimental Values ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Good Agreement

Kinetics of alkaline hydrolysis of crystal violet, a triphenylmethane dye in the micellar environment of cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfonate (SDS) and binary mixtures of these surfactants was studied. The regression parameters, together with rate constants and binding constants were obtained by analyzing the rate surfactant profiles using cooperativity model. It was observed that the reaction was catalyzed by both surfactants. The catalytic factor increased by 10 times in SDS and 38 times in CTAB indicating that binding of crystal violet to the micellar surface is stronger in pure CTAB than SDS but the strength drastically reduced in the mixtures of the surfactants. Reduction of binding constant became more important as the mole fraction of CTAB was improved in the mixture. The kinetic data were investigated using Piszkiewicz model and Raghavan-Srinivasan model. The data obtained from the models were in good agreement with the experimental values.

Kinetic Studies of Copper(II)-exchange from L-Histidine to Human Serum Albumin and Diglycyl-L-histidine, a Peptide Mimicking the Copper(II)-transport Site of Albumin

1975 ◽  
Vol 53 (5) ◽  
pp. 710-715 ◽  
Author(s):  
Show-Jy Lau ◽  
Bibudhendra Sarkar
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
Exchange Rates ◽  
Human Serum ◽  
Kinetic Studies ◽  
Side Chain ◽  
Exchange Reactions ◽  
Equilibrium Study ◽  
Rate Determining Step ◽  
The Difference

The Cu(II)-exchange reactions of L-histidine with human serum albumin and diglycyl-L-histidine were studied at pH 7.53 in 0.1 MN-ethylmorpholine–HCl buffer. The exchange rates from L-histidine to albumin and peptide were determined as 0.67 and 0.42 s−1 respectively. Those from albumin and peptide to L-histidine were obtained as 0.04 and 0.07 s−1 respectively. This result is in accord with the earlier observations of the equilibrium study that the peptide has about half the Cu(II)-binding affinity as compared to albumin. The difference in the Cu(II)-exchange rates of albumin and peptide may reflect the influence of either the COOH-terminal free carboxyl group of the peptide or the side-chain residues of the Cu(II)-binding site in the native protein or both. An exchange mechanism is proposed in which the ternary complexes are shown to play the important role in the rate-determining step in the Cu(II)-exchange between a macromolecule and a small substance.

Hydrolysis of aryl hydrogen maleate esters mediated by cyclodextrins — Effect on the intramolecular catalysis

2005 ◽  
Vol 83 (9) ◽  
pp. 1281-1286 ◽  
Author(s):  
Gabriel O Andrés ◽  
O Fernando Silva ◽  
Rita H de Rossi
Keyword(s):  
Maleic Anhydride ◽  
Transition State ◽  
Rate Constant ◽  
Association Constant ◽  
Kinetic Studies ◽  
Association Constants ◽  
Bulk Solution ◽  
Intramolecular Catalysis ◽  
Hydrolysis Of ◽  
Nonlinear Fashion

Kinetic studies of the hydrolysis of Z-aryl hydrogen maleates (Z = H, p-CH3, m-CH3, p-Cl, m-Cl) were carried out in the presence and absence of hydroxypropyl-β-cyclodextrin (HPCD) at variable pH from 1.00 to 3.00. The reaction involves the formation of maleic anhydride as an intermediate and the rate of its formation is strongly dependent on the pH. This is because the neighboring carboxylate group is a better catalyst than the carboxylic group. The rate constant for the formation of maleic anhydride decreases as the HPCD concentration increases in a nonlinear fashion. The results were interpreted in terms of the formation of a 1:1 inclusion complex of the esters with HPCD. The neutral (HA) and anionic (A) species of the substrate have different association constants (K[Formula: see text] and K[Formula: see text]). In all cases studied, K[Formula: see text] is higher than K[Formula: see text] for the same substrate. This difference is responsible for a decrease in the amount of the anionic substrate (reactive species) in the presence of HPCD, which results in a diminution of the observed rate constant. Besides, the rate constant for the reaction of the complexed substrate is smaller than that in the bulk solution indicating that the transition state of the cyclodextrin mediated reaction is less stabilized than the anionic substrate. The values of ΔΔG‡ are almost independent of the substituent on the aryl ring and range within 0.48 and 1.05 kcal mol–1 (1 cal = 4.184 J). There is no correlation between KTS and the association constant of the substrate indicating that the factors stabilizing the transition state are different from those that stabilize the substrate. Key words: cyclodextrins, intramolecular catalysis, hydrolysis, inhibition.

Temperature effect on the viscoelastic properties of solutions of cylindrical mixed micelles of zwitterionic and anionic surfactants

2010 ◽  
Vol 72 (2) ◽  
pp. 230-235 ◽  
Author(s):  
D. A. Kuryashov ◽  
O. E. Philippova ◽  
V. S. Molchanov ◽  
N. Yu. Bashkirtseva ◽  
I. N. Diyarov
Keyword(s):  
Temperature Effect ◽  
Viscoelastic Properties ◽  
Mixed Micelles ◽  
Anionic Surfactants

scholarly journals Fluorescence Spectroscopy Study on the Interaction of Acetal Cleavable Anionic Surfactants and Bovine Serum Albumin

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Xin Zhang ◽  
Jianhong Bian ◽  
Wenjie Zhai ◽  
Jing Dong ◽  
Huihui Liang ◽  
...  
Keyword(s):  
Bovine Serum Albumin ◽  
Fluorescence Spectroscopy ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Protein Separation ◽  
Anionic Surfactants ◽  
Binding Constants ◽  
Number Of Binding Sites ◽  
Hydrophobic Nature ◽  
Thermodynamic Relationship

The interactions between bovine serum albumin (BSA) and two cleavable anionic surfactants, sodium 3-[(2-nonyl-1,3-dioxolan-4-yl)methoxy]propane-1-sulfonate (SNPS) and sodium 3,3′-(2-nonyl-1,3-dioxane-5,5-diyl)bis(methylene)bis(oxy)dipropane-1-sulfonate (SNDPS), have been studied by means of fluorescence spectroscopy and thermodynamic analysis. The fluorescence of BSA is quenched via a static quenching mechanism with the addition of the surfactants. The binding constants of the surfactants and proteins have been measured, with KA(SNPS) = 8.71×104 M−1 and KA(SNDPS) = 7.08 × 104 M−1, respectively. The interaction between surfactants and BSA is mainly of hydrophobic nature, based on the number of binding sites, n[n(SNPS) = 1.57, n(SNDPS) = 1.47], and the thermodynamic relationship. These results suggest that SNPS and SNDPS could be effective protein denaturants for protein separation and analysis.

scholarly journals The zeta potential measurements in sandpacks saturated with monovalent electrolytes

2018 ◽  
Vol 34 (2) ◽  
Author(s):  
Luong Duy Thanh
Keyword(s):  
Zeta Potential ◽  
Surface Properties ◽  
Electrolyte Concentration ◽  
Particle Surface ◽  
Binding Constants ◽  
Sand Particles ◽  
The Difference ◽  
Group 2 ◽  
Good Agreement ◽  
Group 1

Measurements of the zeta potential in sandpacks saturated with monovalent electrolytes at six different electrolyte concentrations have been reported. The values we record are classified into two groups based on the magnitude of the zeta potential: group 1 (samples S1 and S2) and group 2 (samples S3 and S4). The measured zeta potential in magnitude in group 1 is much smaller than that in group 2 and in literature at the same electrolyte concentration. The reason for a big variation of the zeta potential between group 1 and group 2 may be due to the difference in technique of making sand particles of different size leading to change of particle surface properties. Consequently, the zeta potential that depends on the surface properties would vary. The results show that there is a gradual decrease in the zeta potential with increase in monovalent electrolyte concentration (from 10−4 M to 10−2 M). Additionally, the empirical expressions between the zeta potential and electrolyte concentration are obtained in this work for both group 1 and group 2. The obtained expression for group 2 is in good agreement with those available in literature. From the experimental data in combination with a theoretical model, the binding constants for Na+ and K+ cations are obtained for the samples of group 2 and they are in the same range reported in literature for silica-based samples. 

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