Concentration-dependent dual behavior of hydrophilic ionic liquid in changing properties of aqueous sodium dodecyl sulfate

Modifying physicochemical properties of aqueous surfactant solutions in favorable fashion by addition of environmentally benign room-temperature ionic liquids (ILs) has enormous future potential. Due to its unusual properties, an IL may demonstrate a unique role in altering the properties of aqueous surfactant solutions. Changes in the properties of aqueous sodium dodecyl sulfate (SDS), an anionic surfactant, upon addition of a common and popular "hydrophilic" ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF4] are presented. Addition of low concentrations of [bmim][BF4] (i.e., 相似文献   

Aggregation of sodium dodecyl sulfate in aqueous sodium chloride solutions

Summary Aqueous solutions of sodium dodecyl sulfate with added sodium chloride (0–0.3 mol kg^–1) were studied at 298.2 K in order to calculate the molar standard free energy of micelle formationG _m . The following properties were measured: (i) aggregation number by membrane osmometry, (ii) counter-ion binding and sodium ion activities by electromotive force, (iii) critical micelle concentration by electromotive force and fluorescence spectrophotometry. The results indicate thatG _m . is independent of the NaCl concentration.     

Structure and properties of aqueous dispersions of sodium dodecyl sulfate with carbon nanotubes

The dispersing action of the surfactant (sodium dodecyl sulfate, SDS) on the carbon nanotubes (CNT) in aqueous medium has been studied. Electron microscopy, molecular docking, NMR and IR spectroscopies were applied to determine the physical-chemical properties of CNT dispersions in SDS—water solutions. It was established that micellar adsorption of the surfactant on the surface of carbon material and solubilization of SDS in aqueous medium contribute to improving CNT dispersing in water solutions. It was shown that the non-polar hydrocarbon radicals of a single surfactant molecule form the highest possible number of contacts with the graphene surface. Upon increase of the SDS in solution these radicals form micelles connected with the surface of the nanotubes. At the sufficiently high SDS concentration the nanotube surface becomes covered with an adsorbed layer of surfactant micelles. Water molecules and sodium cations are concentrated in spaces between micelles. The observed pattern of micellar adsorption is somewhat similar to a loose bilayer of surfactant molecules.     

Nonequilibrium electrodialysis of aqueous solution of sodium dodecyl sulfate

Summary Special dialysis apparatus was constructed which enabled to trace a short time nonequilibrium dialysis by the continuous measurement of electric resistance of dialyzing solution. The apparatus is particularly suited for the study of the formation of micelles in surfactant solution. The dialysis curves were constructed by plotting the change of electric resistance against dialysis time. The diagrams consisted of a nearly straight line at low concentration and two nearly straight lines above a certain concentration, from which CMC was sharply determined and the constancy of a single ion concentration above CMC was also demonstrated.

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Zusammenfassung Es wurde ein neuartiger Dialyseapparat entwickelt, der es ermöglicht, die Nichtgleichgewichtsdialyse über kurze Zeiten auszuführen und den Lösungszustand der grenzflächenaktiven Substanzen, die die Mizellen enthalten, genauer zu bestimmen. Die gemessenen Dialysekurven, die die Abhängigkeit des elektrischen Widerstands von der Zeit geben, stellen unterhalb der CMC eine fast gerade Linie dar, während oberhalb der CMC jede Kurve aus zwei geraden Stücken mit einem Knick im Schnittpunkt besteht. Hieraus konnten wir die CMC genau bestimmen und die Konstanz der Zwischenmizellkonzentration feststellen.

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Authors wish to express their thanks to Assistant ProfessorS. Okazaki of Sophia University for her help in this research.     

Photooxidative decomposition of sodium dodecyl sulfate in aqueous solutions

Kinetic features and the mechanism of photooxidative decomposition of sodium dodecyl sulfate in an aqueous solution under the action of pulsed short-wavelength UV light with a continuous spectrum upon introduction of hydrogen peroxide was studied.     

Decomposition of sodium dodecyl sulfate with ozone in aqueous solution

Decomposition of sodium dodecyl sulfate with ozone in aqueous solution in the presence of high concentrations of sodium nitrate was studied. The factors affecting ozone interaction with a dissolved compound were determined.     

Thermodynamic and aggregation properties of sodium dodecyl sulfate in aqueous binary mixtures of isomeric butanediols

The effect of aqueous binary mixtures of isomeric butanediols on the micellization of sodium dodecyl sulfate has been investigated. Conductivity and fluorescence techniques were employed to determine the critical micellar concentration, the degree of dissociation of the counterions and the aggregation numbers of the surfactants in these binary blends. Differential conductivity plots were employed to distinguish between the cooperative and the stepwise aggregation process of the surfactant in each solvent system. The mass-action model was employed to calculate the hydrophobic and the electrostatic contributions to the Gibbs energy of micellization as well as the monomer and the counterion concentrations in the postmicellar region. The thermodynamic parameters calculated for each system indicate that the micellization process occurs more readily in the presence of cosolvent owing to the formation of mixed micelles. Received: 5 July 2000 Accepted: 25 July 2000     

Manipulation and characterization of aqueous sodium dodecyl sulfate/sodium chloride aerosol particles

Aerosol optical tweezers coupled with Raman spectroscopy can allow the detailed investigation of aerosol dynamics. We describe here measurements of the evolving size, composition, and phase of single aqueous aerosol droplets containing the surfactant sodium dodecyl sulfate and the inorganic salt sodium chloride. Not only can the evolving wet particle size be probed with nanometer accuracy, but we show that the transition to a metastable microgel particle can be followed, demonstrating that optical tweezers can be used to manipulate both spherical and non-spherical aerosol particles. Further, through the simultaneous manipulation and characterization of two aerosol droplets of different composition in two parallel optical traps, the phase behavior of a surfactant-doped particle and a surfactant-free droplet can be compared directly in situ. We also illustrate that the manipulation of two microgel particles can allow studies of the coagulation and interaction of two solid particles. Finally, we demonstrate that such parallel measurements can permit highly accurate comparative measurements of the evolving wet particle size of a surfactant-doped droplet with a surfactant-free droplet.     

Structural properties of ionic detergent aggregates: a large-scale molecular dynamics study of sodium dodecyl sulfate

The properties of sodium dodecyl sulfate (SDS) aggregates were studied through extensive molecular dynamics simulations with explicit solvent. First, we provide a parametrization of the model within Gromacs. Then, we probe the kinetics of aggregation by starting from a random solution of SDS molecules and letting the system explore its kinetic pathway during the aggregation of multiple units. We observe a structural transition for the surfactant aggregates brought upon by a change in temperature. Specifically, at low temperatures, the surfactants form crystalline aggregates, whereas at elevated temperatures, they form micelles. We also investigate the dependence of aggregation kinetics on surfactant concentration and report on the molecular level structural changes involved in the transition.     

十二烷基硫酸钠与羟乙基纤维素的相互作用

本文用表面张力(γ)和电导率(κ)方法研究了阴离子表面活性剂十二烷基硫酸钠(SDS)与天然纤维素的水溶性改性物羟乙基纤维素(HEC)的相互作用.实验结果表明,SDS-HEC溶液的γ-lgcSDS曲线和κ～CSDS曲线均呈现双拐点特征,并且γ-lgcSDS曲线上两个SDS临界浓度值(c1 )γ及(c2)γ,与κ～CSDS...     

New thermodynamic/electrostatic models of adsorption and tension equilibria of aqueous ionic surfactant mixtures: application to sodium dodecyl sulfate/sodium dodecyl sulfonate systems

The nonideal adsorbed solution (NAS) theory has been formally extended to adsorption at the air/water interface from aqueous mixtures of ionic surfactants, explicitly accounting for the surface potential of the adsorbed monolayer with the Gouy-Chapman theory. This new ionic NAS (iNAS) theory is thermodynamically consistent and, when coupled to a micellization model, is valid for concentrations below and above the mixed cmc. Counterion binding is incorporated into the model using two fractional binding parameters, beta(sigma) for the adsorbed monolayer and beta(m) for the micelles. The regular solution theory is used to model the nonideal interactions within the adsorbed monolayer and within the mixed micelles. New tension data for an equimolar mixture of sodium dodecyl sulfate (SDS) and sodium dodecyl sulfonate (SDSn) at two salinities fit this model well when mixing is ideal. The total surface densities, the surface compositions, and the surface potentials for the mixed monolayers are calculated. When there is no added salt, at total surfactant concentrations below the mixed cmc, the adsorbed monolayer is enriched in SDSn, but at total concentrations at and above the mixed cmc, the adsorbed monolayer is nearly an equimolar mixture. In the presence of 100 mM NaCl, the adsorbed monolayer is nearly an equimolar mixture, independent of the total surfactant concentration.     

Interaction of a diazoresin with sodium dodecyl sulfate in aqueous solution

The interaction between a diazoresin and sodium dodecyl sulfate (SDS) in aqueous solution was investigated. It was found that the diazoresin-SDS complex dissolves in water containing excessive SDS. The thermal stability and photo-sensitivity of the diazoresin-SDS complex was also studied. The results show that the complex possesses an increased thermal stability while preserving its high photo-sensitivity. An aqueous composition containing diazoresin and SDS was used directly to prepare a photosensitive coating.     

Prediction of thermodynamic properties of sodium dodecyl sulfate aqueous solutions through the hetero-SAFT equation of state

A special version of statistical associating fluid theory (SAFT), the so-called hetero-segmented SAFT equation of state, has been extended to calculate the thermodynamic properties of sodium dodecyl sulfate aqueous solutions. The predicted properties were included the vapor pressure as well as second thermodynamic properties, such as speed of sound. Evaluation of the model has been done through comparison of the calculated vapor pressure with experimental data in the range of 298.15–313.15 K. The hetero-SAFT model is found to be able to correctly describe the thermodynamic derivative properties as well as pVT and VLE properties of ionic surfactant solutions.     

The wettability of polytetrafluoroethylene by aqueous solutions of sodium dodecyl sulfate and propanol mixtures

Advancing contact-angle (theta) measurements were carried out with aqueous solutions of propanol and four series of aqueous solutions of dodecyl sulfate (SDDS) and propanol mixtures at constant dodecyl sulfate concentrations equal to 1 x 10(-5), 6 x 10(-4), 1 x 10(-3), and 1 x 10(-2)M, respectively. The obtained results indicate that in the range of propanol concentrations studied there were considerable contact-angle changes, with exception of the solution series at a constant concentration value of SDDS higher than its critical micelle concentration. From the results of contact-angle measurements and application of the Gibbs and Young equations the ratio of the excess concentration of surfactant and propanol at the solid-aqueous solution interface to the excess of their concentration at the aqueous solution-air interface was calculated. From the calculations it appears that there is a straight linear dependence between the adhesion tension and surface tension of aqueous solutions of SDDS and propanol mixtures, and the slope of the line is equal to -1, which suggests that the surface excess of the SDDS and propanol mixture at the polytetrafluoroethylene-solution interface is the same as the at the solution-air interface. The extrapolation of the straight line to the point corresponding to the surface tension of the aqueous solution, which completely spreads over the polytetrafluoroethylene surface, gives a critical surface tension of wetting equal to 23.7 mN/m. On the basis of the critical surface tension and the Young and modified Szyszkowski equations it was found that in a polytetrafluoroethylene-aqueous solution of the SDDS and propanol mixture, the interface tension can be predicted by the modified Szyszkowski equation.     

Hair protein removal by sodium dodecyl sulfate

The effect of sodium dodecyl sulfate (SDS) on protein loss was studied. Three kinds of human hair were tested by rubbing or immersion in water or immersion in SDS solution, at 25, 40 and 70 degrees C. Under friction, hair treated with SDS solution loses seven times more protein than in water, while by immersion, protein loss is roughly two times higher in SDS than in water. Protein loss increases at higher temperatures. Estimated activation energy values for protein loss by immersion are 69+/-22 kJ mol(-1) for blended brown hair; 40+/-12 kJ mol(-1) for blond hair (tip-end region) and 61+/-4 kJ mol(-1) for blond hair (root-end region) for samples treated in water, while 53+/-8, 7+/-5 and 32+/-8 kJ mol(-1) were the corresponding activation energy values for samples treated in 5% SDS solution. These values indicate that protein loss is mainly a diffusion-controlled process. The more damaged the hair, the lower the activation energy and the higher the protein loss. From these data, it can be estimated that daily care shampooing at room temperature will cause opacity and combing difficulties in 1 year and split ends after 3 years by removal of all cuticle layers.     

Diffusion-controlled evaporation of sodium dodecyl sulfate solution drops placed on a hydrophobic substrate

In this work, the effect of SDS anionic surfactant on the diffusion-controlled evaporation rate of aqueous solution drops placed on TEFLON-FEP substrate was investigated with 11 different SDS concentrations. Drop evaporation was monitored in a closed chamber having a constant RH of 54-57% by a video camera. The initial contact angle, θ(i) decreased from 104±2° down to 68±1° due to the adsorption of SDS both at the water-air and the solid-water interfaces. The adsorption of SDS on the solid surface was found to be 76% of that of its adsorption at the water-air interface by applying Lucassen-Reynders approach. An equation was developed for the comparison of the evaporation rates of drops having different θ(i) on the same substrate. It was found that the addition of SDS did not alter the drop evaporation rate considerably for the first 1200 s for all the SDS concentrations. The main difference was found to be the change of the mode of drop evaporation by varying the SDS concentration. The constant θ mode was operative up to 80 mM SDS concentration, whereas constant contact area mode was operative after 200 mM SDS concentrations due to rapid drop pining on the substrate.     

Effects of addition of short-chain alcohol solvents on micellization and thermodynamic properties of anionic surfactants sodium dodecyl sulfate and sodium dodecyl sulfonate in aqueous solutions

Micellar and thermodynamic properties of anionic surfactants sodium dodecyl sulfate (SDS) and sodium dodecyl sulfonate (SDSn) in aqueous solutions of 5 wt% short-chain alcohols methanol, ethanol, and 1-butanol were investigated by experimental electrical conductivities, densities and sound velocities at 298.15 K. It was found that methanol behaves like a cosolvent and increases the critical micelle concentration (CMC) of both surfactants in aqueous solutions. However, the other investigated alkanols act as a cosurfactant and decrease the CMC by their presence. The values of the degree of counterion association on the micelles of both surfactants in aqueous methanol solution are same as those in pure water, and they decrease with increasing the alkyl chain length of alcohol. Furthermore, the values of the apparent molar volume and isentropic compressibility of the monomeric and micellar forms of the investigated surfactants were obtained from the experimental density and sound velocity data. It was found that the values of the apparent molar properties of both micellar and monomeric forms of the studied surfactants increase by increasing the alkyl chain of the alcohols.     

The solubility of disperse dyes in an aqueous sodium dodecyl sulfate solution

Summary The solubilities of the following compounds in an aqueous sodium dodecyl sulfate solution were determined at 25°, 30°, 35° and 40°C: biphenyl, azobenzene, p-chloroazobenzene, p-aminoazobenzene, p-N,N-dimethylaminoazobenzene and p-nitroazobenzene. From the results the thermodynamic parameters for the transfer of the model compounds from water to SDS micellar environment were calculated. The resulting thermodynamic parameters were not so certain, but suggested that with biphenyl, azobenzene and p-chloroazobenzene which seem to be solubilized in the SDS micellar interior the solubilizing process is a result of a favourable increase in entropy, and that with p-aminoazobenzene, p-N, N-dimethylaminoazobenzene and p-nitroazobenzene which seem to be solubilized in the SDS micellar surface the solubilizing process is a result of a favourable decrease in enthalpy. The favourable increase in entropy was explained in terms of iceberg and the favourable decrease in enthalpy in terms of interfacial energy.