Aqueous Solutions Of Anionic Surfactants Research Articles

Refractive index, conductometric, and fluorescence probe study on interaction of valine with aqueous solution of anionic surfactant, sodium dodecyl surfactant (SDS), at 298.15, 303.15, 308.15 and 313.15 K

Refractive index, conductometric, and fluorescence probe study on interaction of valine with aqueous solution of anionic surfactant, sodium dodecyl surfactant (SDS), at 298.15, 303.15, 308.15 and 313.15 K

Physicochemical study on interaction of valine with aqueous solution of anionic surfactant, sodium dodecyl surfactant (SDS), at 298.15, 303.15, 308.15 and 313.15 K temperatures

Physicochemical study on interaction of valine with aqueous solution of anionic surfactant, sodium dodecyl surfactant (SDS), at 298.15, 303.15, 308.15 and 313.15 K temperatures

Model for estimating activity coefficients in binary and ternary ionic surfactant solutions

We introduce the CMC based Ionic Surfactant Activity model (CISA) to calculate activity coefficients in ternary aqueous solutions of an ionic surfactant and an inorganic salt. The surfactant can be either anionic or cationic and in the present development, the surfactant and inorganic salts share a common counterion. CISA incorporates micellization into the Pitzer–Debye–Hückel (PDH) framework for activities of mixed electrolyte solutions. To reduce computing requirements, a parametrization of the critical micelle concentration (CMC) is used to estimate the degree of micellization instead of explicit equilibrium calculations. For both binary and ternary systems, CISA only requires binary experimentally-based parameters to describe water–ion interactions and temperature–composition dependency of the CMC. The CISA model is intended in particular for atmospheric applications, where higher-order solution interaction parameters are typically not constrained by experiments and the description must be reliable across a wide range of compositions. We evaluate the model against experimental activity data for binary aqueous solutions of ionic surfactants sodium octanoate and sodium decanoate, as common components of atmospheric aerosols, and sodium dodecylsulfate, the most commonly used model compound for atmospheric surfactants. Capabilities of the CISA model to describe ternary systems are tested for the water–sodium decanoate–sodium chloride system, a common surrogate for marine background cloud condensation nuclei and to our knowledge the only atmospherically relevant system for which ternary activity data is available. For these systems, CISA is able to provide continuous predictions of activity coefficients both below and above CMC and in all cases gives an improved description of the water activity above the CMC, compared to the alternative model of Burchfield and Wolley [J. Phys. Chem., 88(10), 2149–2155 (1984)]. The water activity is a key parameter governing the formation and equilibrium growth of cloud droplets. The CISA model can be extended from the current form to include the effect of other inorganic salts with the existing database of binary PDH parameters and using appropriate mixing rules to account for ion specificity in the micellization process.

Thermodynamic, spectroscopic and biological investigation of interaction of anionic surfactants with [Cu(im)6]F2·4H2O complex in aqueous solution

Present study describes the physicochemical behavior of the coordination complex of copper i.e. [Cu(im)6]F2.4H2O (Hexakis(imidazole)copper(II) fluoride tetrahydrate) and its solubilization by anionic surfactants sodium dodecyl sulphate (SDS) and sodium stearate (SS). The detailed investigation was accomplished by electrical conductivity measurements and UV–visible spectroscopy in aqueous solutions of anionic surfactants in the sub micellar and micellar concentration ranges. Furthermore, thermodynamic parameters of complex-surfactant interaction and CMC of both surfactants in the presence of copper imidazole complex were evaluated by electrical conductivity and experimental results revealed an increase in CMC of both surfactants in the presence of complex. CMC increases with rise in temperature and the trend of variation in thermodynamic parameters indicates that the solubilization of copper imidazole complex in micelles of both surfactants is spontaneous and enthalpy as well as entropy driven. Spectroscopic investigation indicates high degree of solubilization and strong interaction in case of complex and SDS than for SS.

A Small-Angle Neutron Scattering Environment for In-Situ Observation of Chemical Processes

A new sample environment for the observation of ongoing chemical reactions is introduced for small-angle neutron scattering (SANS) experiments which enables structural changes to be followed continuously across a wide Q-range in response to changes in the chemical environment. The approach is demonstrated and validated by performing single and multiple potentiometric titrations on an aqueous anionic surfactant solution (oligo-oxyethylene alkylether carboxylic acid in D2O) with addition times varying from 1 s to 2 h. It is shown that the continuous flow set-up offers considerable advantages over classical ‘static’ measurements with regards to sample throughput, compositional precision and the ability to observe fast structural transitions. Finally, the capabilities and ongoing optimisation of the sample environment are discussed with reference to potential applications in the fields of biology, colloidal systems and complex soft matter.

Influence of Salt on Supramolecular Oscillatory Structural Forces and Stratification in Micellar Freestanding Films.

Freestanding films of soft matter containing micelles, nanoparticles, polyelectrolyte-surfactant complexes, bilayers, and smectic liquid crystals exhibit stratification. Stepwise thinning and coexisting thick-thin regions associated with drainage via stratification are attributed to the confinement-induced structuring and layering of supramolecular structures, which contribute supramolecular oscillatory structural forces. In freestanding micellar films, formed by a solution of an ionic surfactant above its critical micelle concentration, both interfacial adsorption and the micelle size and shape are determined by the concentration of surfactant and of added electrolytes. Although the influence of surfactant concentration on stratification has been investigated before, the influence of added salt, at concentrations typically found in water used on a daily basis, has not been investigated yet. In this contribution, we elucidate how the addition of salt affects stepwise thinning: step size, number of steps, as well as the shape and size of nanoscopic nonflat structures such as mesas in micellar foam films formed with aqueous solutions of anionic surfactant (sodium dodecyl sulfate (SDS)). The nanoscopic thickness variations and transitions are visualized and analyzed using IDIOM (Interferometry Digital Imaging Optical Microscopy) protocols with exquisite spatiotemporal resolution (thickness ∼1 nm, time <1 ms). In contrast to nanoparticle dispersions that show no influence of salt on step size, we find that the addition of salt to micellar freestanding films results in a decrease in step size as well as the number of stepwise transitions, in addition to changes in nucleation and growth of mesas, all driven by the corresponding change in supramolecular oscillatory structural forces.

Effect of Monovalent and Divalent Salts on the Interfacial Tension of n-Heptane against Aqueous Anionic Surfactant Solutions

A very low interfacial tension, γ, can be achieved between an oil phase and an aqueous solution containing anionic surfactant and salt at a very low concentration. This phenomenon can have potential applications in recovering residual oil from the reservoir through low salinity–low surfactant enhanced oil recovery flooding. Measurements of γ between n-heptane and aqueous solution of anionic surfactants in the concentration range of 0.141–2.167 mM and salts in the concentration range of 9.010–119.780 mM at 313.15 ± 0.1 K have been carried out. The experimental results show that the value of γ falls to a lowest value at a temperature above the Krafft point when the concentration of anionic surfactants [sodium dodecyl sulfate (SDS) and dioctyl sulfosuccinate sodium salt (AOT)] is increased up to a maximum surface excess concentration in an aqueous solution in the presence of monovalent [sodium chloride, (NaCl)] and divalent [calcium chloride, (CaCl2)] salts in the low concentration range. To understand and a...

Effect of anionic micellar medium on thermo-acoustical parameters of aspartic acid and serine solutions

Density and sound velocity data for aspartic acid and serine in water and in aqueous solution of anionic surfactant; Sodium dodecyl sulphate (SDS) were measured over a temperature range (303.15K–313.15K). Various volumetric and acoustical parameters including apparent molar volume (Φv), partial molar volume (Φvo), partial molar transfer volume, apparent molar isentropic compressibility (Φk), partial molar isentropic compressibility (Φok) and intermolecular free length (Lf) etc. for amino acid solutions in water and in aqueous surfactant (SDS) solutions were calculated from the measured data of density and sound velocity. The abovementioned calculated parameters have been used to explore the amino acid-surfactant interactions. Values of apparent molar volume are positive at all temperatures and are increasing with increasing temperature and amino acids concentrations. Similarly, intermolecular free length decreases with increasing amino acids concentrations both in water and aqueous surfactants solutions, which indicate strong intermolecular interactions in amino acids solutions. From results it is also obvious that due to the presence of resonance stabilization, aspartic acid interacts more strongly in both aqueous and SDS environment than serine.

Surface structure of aqueous ionic surfactant solutions and effects of solvent therein—a computer simulation study

The current paper reports a simulation study on the molecular structure of aqueous solutions of anionic surfactant under the environment of Material Studio 6.0. From the simulated configurations, the concentration-depth profiles of each constituent in the surface layer have been analyzed. With that, the structure of electrical double layer and molecular orientation of surface active dodecyl sulfate ion dependent on its surface density have been derived straightforward. Thereby, the surface pictures of the investigated solutions are mapped out in angstrom scale and become visible. The results demonstrate that the structure of electrical double layer is heavily dependent on the specific counter-ions. However, this dependence is opposite to its experimental counterpart and reversed to that found in the formamide solution. This contradictory finding can be explained by the salvation effect of the counter-ions. Additionally, the orientation of dodecyl sulfate ion is found only subjected to its surface density but hardly influenced by its counter-ion specificity, which keeps coincident to the past investigation on formamide solution.

Influence of bulk concentration on the organisation of molecules at a membrane surface and flux decline during reverse osmosis of an anionic surfactant

Surfactants are extensively used in household and industrial products. Several processes exist to treat industrial wastewaters, including membrane filtration such as ultrafiltration, nanofiltration and reverse osmosis (RO). We studied fouling of RO membranes during filtration of aqueous anionic surfactant solutions under different conditions. The aim was to describe the local organisation of the surfactant at the membrane interface. To this end, the typical surfactant sodium dodecyl sulfate (SDS) and a polyamide membrane (SG, GE Water & Process Technologies) were selected. A marked surfactant mass loss was experimentally quantified and attributed to the accumulation of surfactants on the membrane surface and adsorption on the non-membrane materials in the filtration system. The concentration of surfactant in the polarisation layer compared with the SDS phase diagram, combined with contact angle measurements and flux decline analysis, enabled us to deduce a structure for the fouling. The fouling layer presented different structures according to the surfactant concentration: from a dense hydrophobic layer at very low concentration to a lamellar hexagonal phase in the gel layer at concentrations above 35wt% in water.

Aggregation behavior of tetraphenylporphyrin in aqueous surfactant solutions: Chiral premicellar J-aggregate formation

Porphyrin-surfactant interactions in aqueous solutions are known to result in the selfassembly of various supramolecular structures, including pigment-surfactant complexes, J- and H-aggregates, and solubilized dye species. Detailed studies on the mechanisms of the intermolecular interactions governing the above self-assembly processes allow to predict the aggregation state and hence, the photophysical properties of the dye-surfactant assemblies in order to perform a direct synthesis of the desired porphyrin-based nanostructures at the appropriate experimental conditions. This paper describes a novel example of the surfactant-induced J-aggregate formation from the diprotonated hydrophobic tetraphenylporphyrin species in submicellar aqueous anionic surfactant solutions. The above assemblies are characterized by a rod-like morphology and possess supramolecular chirality according to the CD measurements.

Aggregation state of amphiphilic cationic tetraphenylporphyrin derivatives in aqueous microheterogeneous systems

The conditions for the formation of ionic associates and J- and H-aggregates from amphiphilic cationic tetraphenylporphyrin derivatives in aqueous solutions of anionic surfactants and polyelectrolytes in a wide range of concentrations and pH are considered. The aggregation behaviors of tetraphenylporphyrin and its cationic derivatives in aqueous microheterogeneous systems are compared illustrating the influence of the porphyrin molecular structure on its ability to form supramolecular aggregates of a certain structure. The mechanism of the promoting action of premicellar solutions of anionic surfactants on the formation of J-aggregates of the diprotonated form of cationic porphyrins was proposed. The acid-base properties of a number of new synthetic meso-aryl-substituted porphyrins in aqueous microheterogeneous systems were characterized.

Monomerization of crown-containing phthalocyanines in microheterogeneous organized systems

Optical spectroscopy in the UV and visible ranges, dynamic light scattering, and 1H NMR spectroscopy are used to study monomerization of magnesium octa[(4′-benzo-15-crown-5)oxy]phthalocyaninate (Mgcr8Pc) in aqueous solutions of anionic surfactants: sodium dodecyl benzenesulfonate, sodium bis-(2-ethylhexyl)sulfosuccinate, and sodium deoxycholate (SDBS, AOT, and SDC, accordingly). Structural differences in surfactant molecules determine organization of Mgcr8Pc molecules in microheterogeneous media. It is found that Mgcr8Pc is in a monomeric form in aqueous SDBS solutions at concentrations in the range of CMC1 to CMC2 (critical micelle concentration) and it is in a dimeric and/or aggregate form at concentrations below CMC1. In AOT/water solutions (direct micelles) or hexane/AOT (0.1 M)/water (inverted micelles), Mgcr8Pc is solubilized forming dimeric and/or aggregate forms. In micellar solutions of SDC, the Mgcr8Pc monomer is predominantly formed in the presence of NaCl. The results obtained using the NMR spectroscopy technique agree with the binding of Mgcr8Pc by SDBS micelles similar to solubilization of phthalocyanine by micellar solutions of sodium dodecyl sulfate.

Effect of aqueous solutions of anionic surfactant from sec-alkane sulfate series in mixture with polyacrylamide-based gel on the solubilization of oil and stability of oil-water emulsion

Effect of a polyacrylamide additive to a solution of the surfactant of the sec-alkane sulfate series on the solubilization of oil and stability of an oil-water emulsion at 23°C was studied. It was shown that such parameters as the molecular mass of the polymer and its charge affect the factors under study.

Dispersion and aggregation of single-walled carbon nanotubes in aqueous solutions of anionic surfactants

Understanding the dispersion and aggregation of carbon nanotubes (CNTs) in the aqueous environment are critical for the fate, bioavailability, and the environment and health risk assessment of them because the better suspended CNTs display a higher mobility and could transfer to a longer distance in the environment to possibly pose greater ecological and environmental risks. In this study, we have found that bulk single-walled carbon nanotubes (SWCNTs) could not be dispersed and stably suspended in water and sodium dodecylbenzene sulfonate (SDBS) solution by shaking at 140 r/min, although they could be stably suspended in SDBS solution by sonication. Even through sonication, SWCNTs suspended in SDBS solution do not remain stable at the presence of environmentally relevant cations (e.g., Na + , K + , Ca 2+ , and Mg 2+ ) after dilution. These observations suggest that SWCNTs will not travel long distances in significant concentrations in the natural environment to pose great ecological and environmental risks. We also observed that the re-aggregation of suspended SWCNTs in the presence of cations was dependent on the SDBS concen- tration rather than the SWCNT concentration in the suspension. Both SDBS and sonication play important roles in the dispersion of SWCNTs, with sonication breaking down large aggregates of SWCNTs, while SDBS adsorbed on the SWCNTs inhibits the coagulation and aggregation by steric/electrostatic repulsion to maintain the stability of the suspension in water.

Combination effect of ultrasound and shake as a mechanical action for textile cleaning

The ultrasonic cleaning of artificially soiled fabrics with and without shake was carried out in an aqueous anionic surfactant solution. The polyester, cotton and polyester/cotton (65/35) fabrics were soiled with oleic acid or carbon black as a model soil, and cleaned together with their original fabrics with applying ultrasound for 5min. The detergency and the soil redeposition were determined from the change in the Kubelka–Munk function of the soiled and original fabric surfaces due to the cleaning. For any fabric, the removal of oleic acid and carbon black from the soiled fabric and their redeposition onto the original fabric increased with increasing electric power consumption of ultrasound. When ultrasound and shake were applied at the same time, the detergency further increased for any electric power consumption. The maximum detergency obtained with combination of ultrasound 340W and shake 160spm was compared with detergency obtained with Wascator, a horizontal axis drum type washer. It was found that the ultrasound/shake combination cleaning enabled efficient removal of both soils from any fabric and the detergency of the polyester fabrics was comparable to that with Wascator. The mechanical action during the washing was evaluated by two mechanical action test pieces commercially available, which indicated that the ultrasound/shake combination cleaning provided gentle mechanical action to the fabric in comparison with the drum type washer. The SEM observations showed the damage of the fabric and fiber surfaces was negligibly small after the ultrasound/shake combination washing.

Micellar solubilization of octan-1-ol in aqueous solutions of SDBS and TTAB

Speed of sound and density measurements of aqueous solutions of anionic surfactant, sodium dodecylbenzene sulfonate (SDBS) and cationic surfactant, tetradecyltrimethyl- ammonium bromide (TTAB) in the presence of octan-1-ol, have been measured as a function of concentration of surfactants (0.05 and 0.10) mol·kg−1 at T=(298.15, 303.15 and 308.15) K. From these measurements, the apparent molar volume (Φv) and isentropic compressibility (ks) of octan-1-ol have been computed. The standard partial molar volume (Φov) has been calculated for rationalizing various interactions in the studied solutions. 1H and 13C NMR chemical shift measurements in micelle solutions containing monohydric alcohols have also been carried out in order to interpret the preferential solubilization site of alcohol on the studied micellar systems. Further, FTIR studies suggest that the peak values of OH and –CC– stretching are considerable in hydrophobic alcohols. The results obtained are analyzed in terms of the solute–solvent interaction.

Effect of Mixed Nanobubble and Microbubble Liquids on the Washing Rate of Cloth in an Alternating Flow

AbstractIt is well‐known that laundry waste water contributes to water pollution, and the need to reduce the amount of detergent used is widely recognized. Predominantly, research has focused on the washing effects of microbubbles and nanobubbles, and mechanical work was found to account for about 50 % of the washing effect on the cloth. In the present research, mixed nanobubble and microbubble water and four types of surfactants (including a commercial cleaning liquid) were investigated in an alternating flow system. The nanobubble water achieved a washing rate greater than that of ion‐exchanged water. However, the microbubble water had the same washing rate as ion‐exchanged water. Moreover, nanobubbles mixed with an aqueous solution of surfactant exhibited a washing rate that depended on the ionization of the surfactant: the mixture with nanobubbles and anionic surfactant exhibited a washing rate that was higher than that of aqueous anionic surfactant solution without nanobubbles. The surface tensions of nanobubble water and mixed nanobubble anionic surfactant were lower than those without nanobubble, respectively. Also, there was no advantage in mixed microbubble liquids. These results provide evidence of an enhanced washing effect by nanobubble mixtures in liquids.

Study of Micellization of Aqueous Sodium Dodecylbenzene Sulfonate in Alcohol Solutions

Apparent molar volumes, Φv and isentropic compressibilities, κ s of monohydric long chain alcohols, nonan-1-ol and decan-1-ol in aqueous solution of anionic surfactant, sodium dodecylbenzene sulfonate (SDBS) have been calculated from experimental densities, ρ and speed of sound, u, measured at 298.15, 303.15, and 308.15 K. The standard partial molar volumes, Φ o v have been calculated for rationalizing various interactions in the studied solutions. The critical micelle concentration (cmc), of SDBS in dilute aqueous solution of octan-1-ol, at various temperatures was determined from conductance measurements in the range of ∼0.009 to 0.0734 mol%. Thermodynamic parameters of micellization i.e. standard enthalpy change (ΔH 0 m ), standard entropy change (ΔS 0 m ) and standard Gibbs free energy change (ΔG 0 m ) have been evaluated from temperature dependence of cmc. Further, 1 H and 13 C NMR chemical shift measurements in micelle solutions containing nonan-1-ol and decan-1-ol have also been made and the results are presented and discussed.

On Relationships among the Aggregation Number, Rheological Property, and Turbulent Drag-Reducing Effect of Surfactant Solutions

In this study, turbulent drag-reducing effect, rheological characteristics and micelle aggregation number of aqueous solutions of anionic surfactant, sodium dodecyl sulfate (SDS), and cationic surfactant cetyltrimethylammonium chloride (CTAC) aided with sodium salicylate (NaSal). SDS solution was experimentally investigated at various concentrations in CMCs (critical micelle concentration) with and without sodium chloride. 200 ppm (ppm means part per million) CTAC/NaSal (mass ratio 1 : 1) solution was tested within temperature range from 20°C to 80°C. We were aiming at gaining insights into relationships among turbulent drag reduction rate, rheological properties and micelle microstructures of drag-reducing surfactant solution. Experiments on aggregation number, turbulent drag reduction and shear-rate dependent shear viscosity were performed for solution of SDS and 200 ppm CTAC/NaSal, respectively. The relationships among these three parameters were analyzed and discussed. The results are of importance from both theoretical and practical viewpoints for micellar transitions of surfactant solution.