Effect of 1, 4-dioxane on the micellar properties of some surfactant solutions (original) (raw)
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Precise measurements on the specific conductivity of cationic surfactant (Dodecyltrimethylammonium Bromide) and anionic surfactant (Sodiumdodecyl Sulphate) in methanol-water mixed solvent media containing 0.1, 0.2 and 0.3 volume fractions of methanol are reported at 308.15 K. Specific conductivities of Dodecyltrimethylammonium Bromide and Sodiumdodecyl Sulphate increase with increase in concentration and decrease with increase in the volume fractions of methanol. Critical micelle concentration (cmc) increases with increase in volume fraction of methanol in case of both surfactants. Free energy of micellization (∆Gº m ) has been calculated. Increase in cmc with increase in volume fractions of methanol has been explained in terms of breaking of structure of water due to co-solvent effect.
Physics and Chemistry of Liquids, 2016
The effect of organic solvents, viz., dioxane, dimethylformamide and ethylene glycol on the micellization behavior of cationic surfactants, i.e., tetradecyltrimethyl ammonium bromide (TTAB), tetradecyldimethylbenzyl ammonium chloride (C14BCl) and their dimeric homologue, dimethylene-1,2-bis(tetradecyldimethyl ammonium bromide) (14-2-14) is studied in aqueous solutions using conductometric and viscometric techniques at different temperatures (288.15-318.15 K). It is observed that the critical micelle concentration and degree of counterion dissociation values increase with the increase in volume percentage and the temperature. Studies on the the temperature dependence of the CMC values show that the standard Gibbs free energy of micellization values increase with the concentration of organic solvents and temperature whereas the opposite trend is observed for enthalpy. The randomness of the system decreases in presence of solvents. The relative viscosity of the surfactants was found to be more in presence of ethylene glycol among the studied systems. The effect of temperature on relative viscosity for these systems has also been discussed.
Measurements of the conductance of binary mixtures of cetyltrimethylammonium bromide and sodium dodecylsulfate in pure water and in methanol-water mixed solvent media containing 0.10, 0.20, and 0.30 volume fractions of methanol at 308.15, 318.15, and 323.15 K are reported. The concentration of sodium dodecylsulfate varied from 0.001 to 0.04 molÁL -1 in the presence of *5.0 9 10 -4 molÁL -1 cetyltrimethylammonium bromide. The results showed a sharp increase in the conductance with increasing concentrations of the surfactant mixture. The conductance is found to increase with increasing temperature over the entire concentration range in pure water and in a given mixed solvent medium but is found to decrease with increasing methanol content in the solvent. Estimation of the pre-cmc (S 1 ) and post-cmc (S 2 ) slopes for the CTAB-SDS system, to calculate the critical micelle concentration, provides important insight regarding the solution behavior of the mixed surfactants. The critical micelle concentration (cmc) and degree of micellar dissociation (a) of sodium dodecylsulfate in the presence of cetyltrimethylammonium bromide increase in the methanol-water mixed solvent medium. Additionally, the values of cmc and a increase with increasing temperature. The thermodynamic functions for the micellization were calculated at various conditions.
Colloids and Surfaces A: …, 2005
Studies on adsorption characteristics and micellization of mixtures containing cationic/nonionic surfactant dodecyldimethylamine oxide (DMDAO) and anionic surfactant sodium dodecyl sulfate (SDS) with and without NaCl as studied by surface tension, viscosity, dynamic light scattering (DLS) and small angle neutron scattering (SANS) showed strong synergisms and micellar growth. A large negative interaction parameter, β, using Rubing’s theory for above mixed system was estimated. Sphere-to-rod transition driven by ion–dipole interactions between the dissimilar head groups in mixtures of the two surfactants (total concentration 25–100 mM) was well reflected in DLS and SANS measurements. These results are consistent with the concept that nonidealities of mixing in micelles of oppositely charged mixed surfactant systems are primarily of electrostatic origin with specific interactions.
Micellization and Interaction of Anionic and Nonionic Mixed Surfactant Systems In Water
Colloids and Surfaces A: Physicochemical …, 2005
Interaction between binary surfactant mixtures containing anionic surfactants viz. sodium dodecyl sulphates (NaDS) and magnesium dodecyl sulphates (Mg(DS)2) and a nonionic surfactants viz. dodecyl dodecapolyethylene glycol ether (C12E12) and dodecyl pentadecapolyethylene glycol ether (C12E15) in water at different mole fractions (0–1) were studied by surface tension, viscometry and dynamic light scattering (DLS) methods. The composition of mixed micelles and the interaction parameter, β evaluated from the CMC data obtained by surface tension for different systems using Rubingh’s theory were discussed. Activity coefficient (f1 and f2) of metal dodecyl sulphates (MDS)/C12Em (m= 12, 15) mixed surfactant systems were evaluated, which shows extent of ideality of individual surfactant in mixed system. The estimated interaction parameter indicates an overall attractive interaction in the mixed micelles, which is predominant for NaDS as compared to Mg(DS)2. Counter ion valency has specific effect on the mixed micelles, as Mg(DS)2 has less interaction with nonionic surfactants in comparison to NaDS due to strong condensation of counter ion. The stability factors for mixed micelles were also discussed by Maeda’s approach, which was justified on the basis of steric factor due to difference in head group of nonionic surfactant. DLS measurements and viscosity data reveals the synergism in mixed micelles, showing typical viscosity trends and linearity in sizes were observed.
Journal of Surfactants and Detergents, 2013
Various micelle parameters viz., critical micelle concentration (CMC), counter-ion binding (b), aggregation number (N), hydrodynamic radius (R h ), micelle zeta potential (f) and energetic parameters, free energy of micellization (DG 0 m ), enthalpy of micellization (DH 0 m ) and entropy of micelle formation (DS 0 m ) were determined for sodium dodecylsulfate, and dodecyltrimethylammonium bromide in the presence of NaCl for the former and NaBr for the latter. Conductometry and calorimetry methods were used for the measurements of CMC and energetic parameters. The fluorimetric (static quenching) method was employed to determine N and dynamic light scattering to estimate R h and f. The conductometrically determined b was verified from the CMC values by calorimetry using the Corrin-Harkins equation. The results found for the two surfactants of identical tails but different head groups have been presented and discussed. A detailed report on the salt effect using salts containing counter-ions the same as those in the surfactant is found only limitedly in the literature.
Química Nova, 2011
Mixed micellization and surface properties of cationic and nonionic surfactants dimethyl decyl-, tetradecyl-and hexadecyl phosphineoxide mixtures are studied using conductivity and surface tension measurements. The models of Rubingh, Rosen, and Clint, are used to obtain the interaction parameter, minimum area per molecule, mixed micelle composition, free energies of mixing and activity coefficients. The micellar mole fractions were always higher than ideal values indicating high contributions of cationics in mixed micelles. Activity coefficients were less than unity indicating synergism in micelles. The negative free energies of mixing showed the stability of the surfactants in the mixed micelles.
Journal of Dispersion Science …, 2008
The micellization process of binary surfactant mixtures containing cationic surfactants viz.dodecyl pyridinium halide (C12PyX; X 5 Cl, Br, I), tetradecyl pyridium bromide (C14PyBr),and hexadecyl pyridium halide (C16PyX; X 5 Cl, Br) and a nonionic surfactants viz.dodecyl nonapolyethylene glycol ether (C12E9), dodecyl decapolyethylene glycol ether (C12E10), dodecyl dodecapolyethylene glycol ether (C12E12), and dodecyl pentadecapolyethylene glycol ether (C12E15) in water at different mole fractions (0–1) were studied by surface tension and viscosity methods. The composition of mixed micelles and the interaction parameter 'b' evaluated from the CMC data obtained by surface tension for different systems using Rubingh’s theory were discussed. Activity coefficient (f1 and f2) of cationic surfactant (CnPyBr)/C12Em (n 5 12, 14, 16 and m 5 10, 12, 15) mixed surfactant systems were evaluated, which shows extent of ideality of individual surfactant in mixed system. The stability factors for mixed micelles were also discussed by Maeda’s approach, which was justified on the basis of steric factor due to difference in head group of nonionic surfactant.