Sodium Dodecyl Sulfate System Research Articles

Sum-Frequency Generation Spectroscopy of an Adsorbed Monolayer of Mixed Surfactants at an Air–Water Interface

The effects of various compositions in mixed surfactant solutions of sodium dodecyl sulfate (SDS), an anionic surfactant, and cetyltrimethylammonium bromide (CTAB), a cationic surfactant, at an air–water interface have been investigated using vibrational sum-frequency generation (VSFG) nonlinear optical spectroscopy. The work is focused on understanding the temporal evolution of aggregation behavior of the catanionic system of CTAB and SDS at the charged air–water interface. For the mixed surfactants, the VSFG intensity of the OH stretching bands decreases, whereas that of the CH stretching of alkyl chains increases with time. For the 1:1 ratio of surfactants, the VSFG intensity of the OH stretch vanishes much earlier than the complete growth of the CH stretching modes. Thus, the polar ordering of interfacial water molecules is faster than the time-evolution of alkyl chains of the catanionic system. The temporal growth of the complex between surfactants CTAB and SDS exhibited an induction time (up to ∼200...

Application of modified nano γ-alumina as a solid-phase extraction sorbent combined with high-performance liquid chromatography for determination of phthalate esters in environmental water and soft drink samples

A solid-phase extraction procedure based on sodium dodecyl sulfate (SDS)-coated nano γ-alumina was used for the first time as an effective adsorbent for preconcentration of four phthalate esters in environmental water and soft drink samples for their subsequent determination by high-performance liquid chromatography with ultraviolet detection. The system of anionic surfactant SDS with hemimicelles/admicelles formed on the oxide mineral surface was used. Properties of the nano γ-alumina were characterized by field-emission scanning electron microscopy. Several predominant factors affecting the adsorption of phthalate esters were optimized. Under the optimized conditions, preconcentration of 500 mL of the sample solution permitted a preconcentration factor of 500 for all analytes. The linear response was achieved in the concentration range of 0.1–200 μg L−1. Limits of detection of the method obtained at a signal-to-noise ratio of three ranged between 0.042 and 0.060 μg L−1. The Langmuir adsorption capacity (qmax) was found to be in the range of 66.7–83.3 mg g−1 of the adsorbent. The method was successfully applied for the determination of phthalate esters in different samples with good recoveries ranging from 94.0 to 106.0% with relative standard deviation values below 6%.

Rapid and Sensitive Online Determination of Some Selective α1-Blockers by Flow Injection Analysis with Micelle-Enhanced Fluorescence Detection

A rapid, sensitive and selective flow injection analysis (FIA) method was developed for the determination of some selective α1-blockers including; terazosin (TER), doxazosin (DOX), prazosin (PRZ), and alfuzosin (ALF). The method was based on enhancement of the native fluorescence of the studied drugs in the presence of sodium dodecyl sulfate (SDS). The method was optimized for the buffer type, concentration and pH, surfactant type and concentration, flow rate and detection wavelengths in order to achieve the maximum sensitivity. The results showed that the best sensitivity was obtained by using SDS (10mM) in phosphate buffer (20mM, pH = 3), flow rate was 0.5ml/min and the detector was set at λex = 250 and λem = 389. Under these optimum conditions there was a linear relationship between the concentration and the fluorescence intensity in the range from 5-400ng ml(-) with correlation coefficient of more than 0.998. The detection and quantitation limits for the studied drugs by the proposed method were 3.2-11.9ng ml(-1) and 10.8-39.7ng ml(-1), respectively. The method was validated in accordance with the requirements of ICH guidelines and shown to be suitable for intended applications. Moreover, the binding constants for α1-blockers -SDS system were determined using the adduct model. The proposed method has been applied successfully for the analysis of the pure forms for studied drugs and also their pharmaceutical formulations and the results were compared with official methods.

Polyampholyte-tuned lyotrop lamellar liquid crystalline systems

The influence of a polyampholyte, i.e., poly(N,N′-diallyl-N,N′-dimethyl-altmaleamic carboxylate) (PalH), on the lamellar liquid crystalline (LC) system sodium dodecyl sulfate (SDS)/decanol/water was investigated by means of microdifferential scanning calorimetry, small-angle X-ray diffraction (SAXS), and cryo-scanning electron microscopy. After incorporating PalH into the lamellar liquid crystalline system, SAXS measurements show that three different LC phases exist: i.e., a swelling, slightly swelling, and non-swelling one. At pH 4, the positively charged polymer with an extended conformation can directly adsorb at the anionic head groups of the surfactant and more compact vesicles are formed at room temperature. At pH 9, the electrostatic interactions between the polyampholyte (in a more coiled conformation) and the sulfate head groups of the SDS are leveled off and incompact vesicles are formed at room temperature. That means in presence of the polyampholyte the morphology of the LC phase, i.e., the supramolecular vesicle structure, can be tuned by varying the pH and/or the temperature.

Improvement of Ca2+-tolerance by the introduction of EO groups for the anionic surfactants: Molecular dynamics simulation

The influence of Ca2+ on the aggregation of sodium dodecyl sulfate (SDS), sodium dodecyl oxyethylene sulfate (SDES), sodium dodecyl benzene sulfate (SDBS) and sodium dodecyl benzene oxyethylene sulfate (SDBES) at air–water interface were compared to investigate the role of oxyethylene unit by means of the molecular dynamics simulation. In the SDES and SDBES systems, the interaction between OSO3− groups and Na+ions decreases, the diffusion coefficient of Na+ increases, while the interaction between surfactants and Ca2+ ions increases, and the diffusion coefficient of Ca2+ ions decreases. Unlike SDS and SDBS systems, the EO groups introduced may bind Ca2+ ions and the interaction between Ca2+ ions OSO3− groups is weakened, consequently, the precipitation of anionic surfactant by Ca2+ ion is restrained, i.e., the Ca2+-tolerance of anionic surfactants via the introduction of EO groups may be improved. The present results could help in choosing of anionic surfactants used in aqueous solution with inorganic salts.

Study on the self-assembly properties of fluorinated hydrophobically associating polyacrylamide

The self-assembly of a fluorinated hydrophobically associating polyacrylamide (UFPAM) prepared by emulsifier-free ultrasound-assisted radical polymerization was studied using fluorescence spectroscopy (FS), rheological measurements, and dynamic light scattering (DLS). The effects of the degree of mineralization (M), temperature, and the concentrations of ionic surfactants—sodium dodecyl sulfate (SDS) and cetyltrimethyl ammonium bromide (CTAB)—on the self-assembly behavior of UFPAM were explored in detail. The results showed that 2,2,3,4,4,4-hexafluorobutyl methacrylate (FA) was effectively incorporated into the UFPAM. As the concentration of UFPAM increased, the hydrophobic self-assembly behavior of UFPAM increased the apparent viscosity and enhanced the structural network of UFPAM, as indicated by the Ostwald–de Waele power-law model, FS, dynamic rheological measurements, and DLS. The maximum apparent viscosity of the UFPAM solution occurred when the polarity of the solution was enhanced in mineralized solution and the polymer coils were expanded at increased temperature. Provided that the concentration of the ionic surfactant was below its CMC, the addition of CTAB promoted the self-assembly of UFPAM, but this did not occur upon the addition of SDS. When the concentration of the surfactant was above the CMC, the aggregation number increased in the UFPAM–CTAB system, whereas it exhibited a minimum value in the UFPAM–SDS system.

Microstructure transformation of PDMS-E grafted gelatin polymers induced by SDS and SDBS

Inorganic–organic hybrid materials with tunable chemical and physical properties were prepared from mono epoxy terminated polydimethylsiloxane (PDMS) macromonomer and gelatin for improving their flexibility and hydrophobicity. Sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS) were used to enhance the compatibility of two polymers phases. Measurement of grafting density indicated that anionic surfactants played a crucial role in deciding the detailed microstructure of PDMS-E grafted gelatin (PGG) polymers in alkaline solution. The interaction between gelatin and SDS/SDBS was investigated by viscosity and SEM. Viscosity analysis showed a regular increase in SDS system and a steeper change in the case of SDBS. SEM micrographs displayed a series of structural transitions (spherical, spindle, irregular granular and spherical aggregates) with the increase of SDS concentration, but spindle and granular aggregates appeared alternately as varying SDBS concentrations. The results demonstrated that both the electrostatic and hydrophobic interactions between anionic surfactant and gelatin controlled the aggregate structure of gelatin–SDS/SDBS, which affected the compatibility between gelatin and PDMS. Thermal properties of PGG polymers had changed with the modification of polymer microstructure. The results above revealed that microstructure transformation of PGG polymers was determined by the compatibility of two polymers in anionic surfactant aqueous solution and the chemical nature of their monomers.

Comparison of the effects of anionic and cationic surfactant concentration on mean drop size in a mixer-settler extractor

In this study, the effect of Aniline and SDS (Sodium Dodecyl Sulfate) surfactant on mean drop size, D32, was investigated in a horizontal mixer-settler. For this purpose, three series of experiments were conducted in a single stage mixer-settler on the liquid–liquid dispersion of a toluene–water system. At first, the effects of impeller speed and hold-up on the mean drop size were examined without any surfactant. Afterwards the same investigation was performed in the presence of SDS (Seri 1) and then in the presence of Aniline (Seri 2). The results revealed that D32 in Aniline system is larger than D32 in SDS system. In addition, the results show that D32 in the presence of Aniline depends on the impeller speed with a power low function, having an exponent of −1.11 which has a good agreement with Hinze–Kolmogorov's theory.

Mutual Influence of Sodium Dodecyl Sulphate and Calcium Propionate in Biocidal Activity and Corrosion Inhibition of Carbon Steel

The inhibition and biocidal efficiency of sodium dodecyl sulphate (SDS) and calcium propionate (CP) in controlling corrosion of carbon steel immersed in an aqueous solution has been evaluated by weight loss and biocidal efficiency method in the absence and presence of Zn2+. The formulation consisting of CP and Zn2+ has excellent inhibition efficiency (IE). The biocidal efficiency of this formulation is 46 %. To improve the biocidal efficiency a third substance SDS is added. A synergistic effect is noticed between SDS, Zn2+ and CP. The formulation consisting 50 ppm of calcium propionate, 200 ppm of SDS and 50 ppm of Zn2+ shows 99 % IE and 100 % biocidal efficiency. Addition of SDS enhances the IE of Zn2+ and CP system. Electrochemical studies were carried out to find out the nature of the corrosion inhibitor. The CP–Zn2+–SDS system functions as a mixed inhibitor. The scanning electron micrographs and atomic force micrographs reveal the formation of a protective film on the metal surface.

Comparison of the influence of fluorocarbon and hydrocarbon surfactants on the adsorptions of SDS, DTAB and C12E8 at the air/water interface by MD simulation

Adsorptions of sodium dodecylsulfate (SDS), dodecyltrimethylammonium bromide (DTAB) and octaethylene glycol monododecyl ether (C12E8) at the air/water interface in the presence of hydrocarbon and fluorocarbon surfactants (HCEP and FCEP) were investigated by molecular dynamics (MD) simulation. With the addition of HCEP or FCEP, the monolayer is more organized than in individual surfactant systems. Extremely expanded C12E8 chain in a smaller tilt angle is discovered in C12E8/HCEP system. In SDS or DTAB systems, relatively small tilt angle of surfactants is observed in the presence of FCEP. Their analog, a silicone surfactant DSEP shows a favorable effect on interfacial properties with DTAB.

Effects of different factors on the forward extraction of soy protein in reverse micelle systems

Reverse micelle extraction is a new technology for the extraction of protein. In this research, three kinds of reverse micelle systems, anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelle system, sodium dodecyl sulfate (SDS) reverse micelle system, and cationic surfactant cetyltrimethyl ammonium bromide (CTAB) reverse micelle system, were used to extract soy protein respectively. Effects of soy flour concentration, Wo ([H 2 O]/[AOT]), temperature, time, pH, ionic strength and ultrasonic power on forward extraction efficiency of soy protein were investigated. The effect of AOT reverse micelle diameter was studied as well. AOT reverse micelle system had higher extraction efficiency than SDS and CTAB systems. The main factors that affected the forward extraction were soy flour concentration, temperature and pH. The optimal conditions in AOT system were soy flour concentration being 0.007 g/ml, Wo 16, pH 6.5, temperature 34°C, time 20 min, KCl concentration of 0.1 mol/L and ultrasound power of 240 W. Under these conditions, the extraction efficiency of soy protein was 85.5%. The forward extraction efficiency of soy protein in AOT reverse micelle system increased with the increase of the reverse micelle diameter. Reverse micelle extraction is an effective way to extract soy protein. Key words: Soy protein, reverse micelle, forward extraction, sodium bis(2-ethylhexyl) sulfosuccinate (AOT), sodium dodecyl sulfate (SDS), cetyltrimethyl ammonium bromide (CTAB).

Effect of Oil/Water Ratios on the Phase Behavior and the Solubilization Ability of Microemulsion Systems Containing Sodium Dodecyl Sulfate

An α–e–β fish-like phase diagram of three phase microemulsions was proposed and used to investigate the phase behavior of the microemulsion systems sodium dodecyl sulfate (SDS)/alcohol/oil/water at various oil/water ratios. Related physicochemical properties of the microemulsion systems were calculated. As the oil/water mass ratio increases, the solubility (e B) of the alcohol increases, while both the mass fraction of alcohol in the interfacial layer (A S) and the solubilization ability (SP ∗) decrease. The effect of oils on the properties of the microemulsion systems was investigated.

Resonance Rayleigh Scattering, Second-Order Scattering and Frequency Doubling Scattering Spectra of Copper(II)-Flutamide System with Anionic Surfactants and its Analytical Application

A simple, sensitive, and rapid method based on ion association, for the determination of FLD has been developed. Flutamide (FLD) can react with Cu(II) to form 1:1 cationic chelate at pH 2.2-7.0 Mclivaine buffer medium, which can further react with anionic surfactants (AS) such as sodium dodecyl sulfate (SDS), sodium lauryl sulfonate (SLS) and sodium dodecylbenzene sulfonate (SDBS) to form 1:1 ion-association complexes. As a result, the resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS) were enhanced to the highest degree. The maximum RRS, SOS and FDS wavelengths of three ion-association complexes were located at 345/345 nm, 610/305 nm and 430/860 nm, respectively. The increments of scattering intensity (ΔI) were directly proportional to the concentration of FLD in certain ranges. The detection limits (3σ) of FLD for SDS, SLS and SDBS systems were 1.9 ng ml(-1), 2.1 ng ml(-1) and 2.2 ng ml(-1)(RRS method), 2.4 ng ml(-1), 2.7 ng ml(-1) and 2.6 ng ml(-1) (SOS method) and 2.3 ng ml(-1), 2.4 ng ml(-1) and 2.5 ng ml(-1) (FDS method), separately. The sensitivity of RRS method was higher than those of FDS and SOS methods. The optimum conditions of RRS method and the influence factors, the composition and the reaction mechanism have been discussed. Since the method is highly selective, it does not interference concomitant substances. These methods were applied successfully for the determination of FLD in pharmaceutical formulation and urine samples.

Thermodynamic parameters and counterion binding to the micelle in binary anionic surfactant systems

Competitive counterion binding of sodium and calcium to micelles, and mixed micellization have been investigated in the systems sodium dodecylsulfate (NaDS)/sodium decylsulfate (NaDeS) and NaDS/sodium 4-octylbenzenesulfonate (NaOBS) in order to accurately model the activity of the relevant species in solution. The critical micelle concentration (CMC) and equilibrium micelle compositions of mixtures of these anionic surfactants, which is necessary for determining fractional counterion binding measurements, is thermodynamically modeled by regular solution theory. The mixed micelle is ideal (the regular solution parameter β M = 0) for the NaDS/NaOBS system, while the mixed micelle for NaDS/NaDeS has β M = −1.05 indicating a slight synergistic interaction. Counterion binding of sodium to the micelle is influenced by the calcium ion concentration, and vice versa. However, the total degree of counterion binding is essentially constant at approximately 0.65 charge negation at the micelle’s surface. The counterion binding coefficients can be quantitatively modeled using a simple equilibrium model relating concentrations of bound and unbound counterions.

Self-Aggregation of Synthesized Novel Bolaforms and Their Mixtures with Sodium Dodecyl Sulfate (SDS) and Cetyltrimethylammonium Bromide (CTAB) in Aqueous Medium

Bolaforms B(1), B(2), and B(3) of the formulas, Br(-)Me(3)N(+)(CH(2))(10)N(+)Me(3)Br(-), Br(-)Me(3)N(+)(CH(2))(10)OH, and Br(-)Me(3)N(+)(CH(2))(10)COO(-)Na(+), respectively, were synthesized, and their properties in the bulk as well as at the air/aqueous NaBr (10 mM) solution interface have been studied. Their interactions with sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) also have been investigated. Tensiometry, conductometry, spectrophotometry, and microcalorimetry techniques were used for characterization and estimation. Both pure bolaforms and their mixtures with SDS and CTAB have been found to self-aggregate, forming micelles in solution. The mixed systems of bolaform and SDS have been observed to form both micelles and vesicles. Their mutual interactions were synergistic, which at the interface was more spontaneous than in the bulk. The interfacial and bulk compositions of the mixed binary systems (bolaform and SDS or CTAB) with their associated interaction parameters have been estimated from the Rosen interaction model and the regular solution theory of Rubingh, respectively. The formed vesicles have been found to entrap the water-soluble dye, bromophenol blue, and the dye solubilized vesicles of B(1)-SDS and B(2)-SDS completely eluted out of the sephadex column proving their formation. A rough estimation of the size and polydispersity index of the formed micelles and vesicles has been made from DLS measurements.

DNA对Ru(bpy)2(dppx)2+-SDS体系共振光散射的猝灭作用及其应用

The resonance light scattering (RLS) spectra of Ru (bpy) 2 (dppx) (superscript 2+)-SDS-DNA (bpy=2, 2'-bipyridine; dppx=7, 8-dimethyl-dipyrido [3, 2-a: 2', 3'-c] phenazine) system was studied. The results show that the solution of Ru (bpy) 2 (dppx) (superscript 2+)-SDS exhibits a high RLS signal in the presence of the premicellar aggregation of an anionic surfactant, sodium dodecyl sulphate (SDS), and adding DNA in the solution of Ru (bpy) 2 (dppx) (superscript 2+)-SDS results in the quenching of the RLS. The mechanism of the reaction was explored. Based on the quenching effect of DNA on the RLS of Ru (bpy) 2 (dppx) (superscript 2+)-SDS system, a novel RLS method for the determination of DNA was proposed. Under optimal conditions, the quenched intensity of RLS at 393 nm is proportional to the concentration of DNA. The linear range of the determination is 0.01~1.2 mg/L. The detection limit is 1.5 μg/L. This method was successful applied to the determination of DNA in synthetic and real samples.

Polymer-Modified Bicontinuous Microemulsions Used as a Template for the Formation of Nanorods

This article is focused on the characterization of the poly(ethylene glycol) (PEG)-induced bicontinuous microemulsion of the pseudo-ternary system sodium dodecylsulfate (SDS)/xylene-pentanol/water by means of differential scanning calorimetry, rheology, and conductometry. The influence of the polymer concentration (cp) and the molecular weight (Mw) on the microstructure of the microemulsion was investigated using Cryo scanning electron microscopy. It was found that an increase of cp influences the structure of the sponge-like phase significantly. These polymer-modified microemulsions can be used as a template phase for the formation of BaSO4 nanorods, where individual nanoparticles (5 nm in size) are ordered along the polymer backbone.

Surfactant Gel Extraction of Gold(III), Palladium(II), Platinum(II), and Lead(II) as Thiourea-complexes

Anionic surfactant solutions of sodium dodecylbenzenesulfonate (SDBS) and sodium dodecylsulfate (SDS) separate into two phases through cooling of the solution and the addition of salts. Thiourea (TU) reacts with many metals to form cationic complexes of [M(TU)(n)](m+); some of them extract into the SDBS phase. The separation was examined for lead and tin in commercially purchased solders. More than 95% lead was extracted into the SDBS phase, while tin remained in the aqueous phase. An abnormal decrease in extractability was observed for the [M(TU)(n)](m+) of noble metal complexes at low metal concentrations. The surfactant phases of SDBS and SDS were confirmed as lamellar structures using small angle X-ray scattering (SAXS), and the stability and rigidity of this structure influenced the extractability of the [Au(TU)(n)](3+) complex. The separation of gold(III) and palladium(II) was examined for the SDS system.

Influence of anionic surfactant on the rheological properties of hydrophobically modified polyethylene-oxide/cyclodextrin inclusion complexes

Associative polymers, such as hydrophobic ethoxylated urethane (HEUR), interact with various cyclodextrins (CDs) to form inclusion complexes in aqueous solution. The rheological behavior of HEUR/CD inclusion complex solutions can be manipulated by the introduction of an anionic surfactant, such as sodium dodecyl sulfate (SDS), and such behavior is dependent on the characteristics and types of CD. The introduction of SDS partially restores the viscoelastic behavior of the HEUR/methylated β-CD (m-βCD) system, but it completely recovers the viscoelastic behavior of the HEUR∕α-CD system. Such difference is attributed to the different binding affinity of SDS and CDs. Temperature dependence of the viscoelastic behavior revealed that the activation energy and plateau modulus for HEUR∕α-CD∕SDS system were higher than those of the HEUR∕m-βCD∕SDS system. In excess amounts of SDS, the interaction between SDS and HEUR/CD inclusion complexes was similar to that of SDS and HEUR. Isothermal titration calorimetric study ...

Fractal research on AFM images of polycrystalline aluminum surface with adsorption film of SDS inhibitor

We propose a new method of fractal analysis of the phase images obtained by the atomic-force microscopy (AFM) to study the properties of molecular adsorption films of corrosion inhibitors on the coarse polycrystalline surface, which can hardly be distinguished by using AFM height images due to the roughness of the surface. The system of polycrystalline aluminum and SDS (Sodium Dodecyl Sulfate) inhibitor is chosen as the research object. The electrochemical measurements of aluminum electrodes precoated with SDS films are carried out in HCl solutions, and the results show that the inhibition efficiency increases with the concentration of SDS in the prefilming solution and then remains nearly constant as the CMC (critical micelle concentration) of SDS is exceeded. The fractal analysis of the AFM images of prefilmed aluminum surfaces obtained in SDS solutions is performed and demonstrates that, as the SDS concentration increases, no obvious changes are observed for the fractal dimensions of height images, whereas the phase images present regular changes in the values of fractal dimensions, thus displaying the consistent alteration rule as revealed by electrochemical tests. The results prove the feasibility of the fractal analysis of AFM phase images in characterizing the adsorption behavior of the corrosion inhibitor on polycrystalline coarse surfaces.