Sodium Lauryl Ether Sulfate Research Articles

Effects of Anionic Surfactants on the Water Permeability of a Model Stratum Corneum Lipid Membrane

The stratum corneum (SC) is the ourtermost layer of the epidermis and has a brick-and-mortar-like structure, in which multilamellar lipid bilayers surround flattened dead cells known as corneocytes. The SC lipid membranes provide the main pathway for the transport of water and other substances through the SC. While the physicochemical properties of the SC can be affected by exogenous materials such as surfactants, little is known about how the water barrier function of the SC lipid membranes is compromised by common surfactants. Here, we study the effect of common anionic surfactants on the water permeability of a model SC lipid membrane using a quartz crystal microbalance with dissipation monitoring (QCM-D). Particularly, the effect of sodium dodecyl sulfate (SDS) and sodium lauryl ether sulfate (SLES) is compared. These two surfactants share commonality in their molecular structure: sulfate in the polar headgroup and the same apolar tail. The mass of the lipid membranes increases after the surfactant treatment at or above the critical micelle concentration (CMC) of the surfactants due to their absorption into the membranes. The incorporation of the surfactants into the lipid membranes is also accompanied by partial dissolution of the lipids from the model SC lipid membranes as confirmed by Fourier-transform infrared (FT-IR) spectroscopy. Although the water sorption of pure SDS is much lower than that of pure SLES, the water sorption of SDS-treated membranes increases significantly similar to that of SLES-treated membranes. By combining QCM-D and FT-IR spectroscopy, we find that the chain conformational order and stiffness of the lipid membranes decrease after SDS treatment, resulting in the increased water sorption and diffusivity. In contrast, the conformational order and stiffness of the SLES-treated lipid membranes increase, suggesting that the increased water sorption capacity of SLES-treated lipid membranes is due to the hygroscopic nature of SLES.

Application of ion mobility spectrometry in study of surfactants adsorbed on different dish surfaces

Sodium lauryl sulfate (SLS) and sodium lauryl ether sulfate (SLES) are commonly used in many dishwashing liquids. These chemicals are adsorbed on the dish surface during the washing process and then transferred to food or drink in the cooking process. In this work, the adsorption of SLS and SLES on different dish surfaces in aqueous solution was studied. Stainless steel, copper, aluminum, Pyrex, Teflon and arcopal china ware were used in this study. The adsorbed chemical remained on the surface after rinsing was measured by thermal desorption using an ion mobility spectrometer as the detector. Although arcopal china ware showed the maximum amount of adsorption, and Pyrex and stainless steel dishes showed the minimum amount of residual chemical, the results showed that the amount of adsorbed chemicals on dish surfaces is less than 428 ng.cm−2, which is well below the health risk dosage. The released SLS and SLES from dish surfaces into cold or hot water were also measured and compared for different dishes.

Fragrance solubilization in temperature insensitive aqueous microemulsions based on synergistic mixtures of nonionic and anionic surfactants

Well-defined tetraethylene glycol monooctylether (C8E4) and its commercial polydispersed counterpart (Dehydol® O4) were used to solubilize fragrances. Addition of small amounts (≤1wt.%) of the ionic surfactants, sodium dodecylsulfate (SDS) or sodium lauryl ether sulfate (SLES), permits the formulation of temperature insensitive fragrance in water microemulsions. The investigation of the pseudo-ternary surfactants/β-pinene/water systems allows the determination of the optimum temperature T* as well as the assessment of the efficiency of the surfactant mixtures to solubilize β-pinene. A mixture of Dehydol O4 and SDS (9/1wt.%) can solubilize 6.5wt.% of β-pinene in water within the temperature range of 25–80°C. This synergistic formulation was also applied to the solubilization of p-cymene, the essential oils pinus pinaster and pinus sylvestris and a true fragrant mixture composed of 9 terpenes and terpenoids in dipropylene glycol.

Improved Deproteinization Process for Protein-Free Natural Rubber Latex

Hev b1-14 type proteins in natural rubber latex (NRL) have been identified as allergens in immunogenic responses. Several methods have been developed to reduce these proteins from NRL such as enzyme treatment, centrifugation, creaming, simple or ultrasonic leaching, and chlorination. In this work, the improvement of deproteinization of NRL was developed using the combination of enzyme treatment and leaching processes. The fresh NRL was incubated with 0.2 phr proteolytic alcalase enzyme, and preserved with 2%v/v paraben concentrate in the presence of a 2%v/v sodium lauryl ether sulfate (SLES) as a surfactant at 37°C for 24 hours, and then centrifuged. The upper rubber mass was then leached for three times with either distilled water, a 1%v/v SLES solution, or a mixture of 1%v/v SLES and 2.5%v/v ethanol, and then finally re-dispersed in distilled water. It was found that the increasing process of leaching with either 1%v/v SLES or a mixture of 1%v/v SLES and 2.5%v/v ethanol had the higher efficacy to reduce the remained protein in deproteinized NRL (DNRL). The best deproteinized process was the enzyme treatment and followed by the three times leaching process with a mixture of 1%v/v SLES and 2.5%v/v ethanol, that could completely reduce the proteins in DNRL to 0%. This DNRL had the pH value, viscosity, dry rubber content, and total solid content of 7.41, 13.82 cps, 42.57%, and 44.63%, respectively. Its particle size was 626.23 nm with low polydispersity index of 0.16. The negative charge of SLES could increase the higher negative charge of DNRL to-63.20 mV that exhibited very good physical stability during storage. In conclusions, the combination of enzyme treatment and leaching process with both SLES and ethanol was successful to produce the protein-free DNRL. This DNRL could be further used for several applications including medical skin products.

Chitosan‐sodium lauryl ether sulfate particles and their use for adsorption of Cu(II) ions

AbstractThe synthesis of small particles through the interaction between chitosan (CS) and sodium lauryl ether sulfate (SLES) was studied. Depending on working condition, microparticles at atmospheric pressure and ultrafine particles at high pressure have been obtained. At atmospheric pressure, the microparticles were formed instantaneously when the CS solution was dripped into the SLES aqueous solution. To obtain ultrafine particles, the surfactant solution in contact with high pressure carbon dioxide was sprayed into chitosan solution. Fourier Transform Infrared Spectroscopy proves the interaction between the sulfate groups of SLES and the amino groups of CS. The Scanning Electron Microscopy reveals that the microparticles are quasi‐spherical, but some of them can take the form of pellets depending on preparation conditions. The obtained microparticles were successfully used to uptake Cu(II) ions from aqueous solutions. The adsorption of Cu(II) depends on pH being maximum at pH = 5.5. The kinetic experiments demonstrated that Cu(II) adsorption onto CS/SLES microparticles obeys the Langmuir model. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40059.

The Formation of Surface Multilayers at the Air–Water Interface from Sodium Polyethylene Glycol Monoalkyl Ether Sulfate/AlCl3 Solutions: The Role of the Size of the Polyethylene Oxide Group

Neutron reflectivity, NR, and surface tension, ST, have been used to study the surface adsorption properties at the air-water interface of the anionic surfactant sodium polyethylene glycol monododecyl ether sulfate (sodium lauryl ether sulfate, SLES) in the presence of Al(3+) multivalent counterions, by the addition of AlCl3. In the absence of AlCl3 and at low AlCl3 concentrations monolayer adsorption is observed. With increasing AlCl3 concentration, surface multilayer formation is observed, driven by SLES/Al(3+) complex formation. The onset of multilayer formation occurs initially as a single bilayer or a multilayer structure with a limited number of bilayers, N, ≤3, and ultimately at higher AlCl3 concentrations N is large, >20. The evolution in the surface structure is determined by the surfactant and AlCl3 concentrations, and the size of the polyethylene oxide group in the different SLES surfactants studied. From the NR data, approximate surface phase diagrams are constructed, and the evolution of the surface structure with surfactant and electrolyte concentration is shown to be dependent on the size of the polyethylene oxide group. As the polyethylene oxide group increases in size the multilayer formation requires increasingly higher surfactant and AlCl3 concentrations to promote the formation. This is attributed to the increased steric hindrance of the polyethylene oxide group disrupting SLES/Al(3+) complex formation.

Anti-fog chitosan/sodium lauryl ether sulfate films

The aim of this study was the preparation and characterization of hydrophobic–hydrophilic chitosan films obtained through interaction between the cationic biopolymer, chitosan (CH), with sodium lauryl ether sulfate (SLES), an anionic surfactant, which has also nonionic surfactant properties. The chitosan flat films were obtained at different concentrations of SLES, in the range of 0.02–0.1 M, where spherical capsules were also obtained. The wettability, quantified by the values of contact angle, indicated the hydrophobic character of the films. The significant values of swelling capacity in water, and in 1 % acetic acid solution confirmed the hydrophilic character of the obtained films. Weight loss of CH/SLES films after 24 h, in water and 1 % acetic acid solution was less than 3 % for the all samples. The structure of CH/SLES complex was determined by FTIR spectroscopy method. The morphology of CH/SLES film surfaces determined by atomic force microscopy showed a film surface with nanoroughness structure, determined by the SLES self-assembled nanostructures. The obtained CH/SLES films are transparent and have anti-fogging properties, compared with CH/sodium lauryl sulfate film, which is also transparent but, it gets fogged when coming in contact with warm air.

A blend of Sodium Humate/SLES/Herbal Oils

A blend of sodium humate (SH) with anionic surfactants such as sodium lauryl ether sulfate (SLES) was prepared by solution mixing at medium of herbal oils at 25, 50 and 75°C. Its miscibility studies were carried out by using physical techniques over an extended range of concentration and composition in buffer solution. In addition, to ascertain the state of miscibility of the blends, they were investigated by using UV-visible spectrophotometer and Fourier transform infrared (FTIR). These values revealed that the blend is miscible when the sodium humate content is more than %60 in the blend at all temperatures. There were no important differences in the characteristics of the blends at different temperatures. It was thought that the mechanism of the complex formation is realized by making strong intermolecular interaction like hydrogen bonds between the carbonyl groups in humic acid and hydroxyl groups in fatty acids.

Adsorbent tannin foams: New and complementary applications in wastewater treatment

Tannin rigid foams were synthesized at lab scale in order to confirm their feasibility in wastewater treatment. Different water samples containing three emerging contaminants (Methylene blue, Polyoxyethylene (3.5) sodium lauryl ether sulfate and Trimethoprim) were subjected to adsorption process with these novel products. The experimental results confirmed the ability of these foams for removing anionic and cationic contaminants through adsorption process. Kinetic data were adjusted to Lagergren, Ho and Elovich model. Both the second and the third one presented an average r2 above 0.96. Equilibrium studies on the three studied systems revealed Langmuir and Freundlich models were also adequate for predicting the behavior of the adsorption process. High adsorption capacities were reached (ca. 215, 65 and 25mgg−1 for dye, surfactant and pharmaceutical respectively), which were comparable to other commercial adsorbents already available and functional in wastewater treatments. Therefore, this new ability must be added to the list of advantages these new materials seem to present.

Geotechnical properties of some organoclays

The engineering characteristics of clay are dependant on its mineral and chemical structure. When the clay soils interacted with water, their volume and shear strength and compressibility properties change gradually. Large amount of decrease in terms of the shear strength of clay soils due to swelling is observed. In order to solve these problems, the stabilization of clay soils using chemical additives is a prevalent subject of research. In view of this, previous research studies have employed surface active surfactants to modify the fundamental properties of soft clays. In this study, surfactant–clay complexes (organoclays) were developed using a raw clay modification with four surfactants and their geotechnical properties were determined in laboratory conditions. Two of the surfactants are cationic (cetyl trimethyl ammonium chloride, denoted as CTAC and quaternised ethoxylated fatty amine, denoted as QEFA) and the others are anionic (linear alkylbenzene sulphonic acid, denoted as LABSA and sodium lauryl ether sulfate, denoted as SLES). The experimental results indicated that the geotechnical properties of organoclays show significant change when compared to those of natural clay. The specific gravities, unconfined compression strengths and maximum dry densities of all organoclays were decreased. Optimum moisture content and swelling pressure values were decreased in cationic surfactant modified clays. However, the optimum moisture content and swelling pressure values of anionic surfactant clays are increased. A direct shear test was performed to determine the shear strength of organoclays. The test results also showed that the internal friction angles of organoclays were increased. Additionally, the change in the hydraulic conductivity was found to be insignificant.

Foam-Assisted Delivery of Nanoscale Zero Valent Iron in Porous Media

AbstractFoam is potentially a promising vehicle to deliver nanoparticles for vadose-zone remediation because foam can overcome the intrinsic problems associated with solution-based delivery, such as preferential flow and contaminant mobilization and spreading. In this work, the feasibility of using foam to deliver nanoscale zero valent iron (nZVI) in unsaturated porous media was investigated. Foam generated using the surfactant sodium lauryl ether sulfate (SLES) showed excellent ability to carry nZVI. SLES and nZVI concentrations in the foaming solutions did not affect the percentages of nZVI concentrations in foam relative to nZVI concentrations in the solutions. When foams carrying nZVI were injected through the unsaturated columns, the fractions of nZVI exiting the column were much higher than those when nZVI was injected with liquid. The enhanced nZVI transport implies that foam delivery could significantly increase the radius of influence of injected nZVI. The type and concentrations of surfactants a...

Time-resolved fluorescence quenching studies of sodium lauryl ether sulfate micelles

Time-resolved fluorescence quenching studies of sodium lauryl ether sulfate micelles

Time-Resolved Fluorescence Quenching Studies of Sodium Lauryl Ether Sulfate Micelles

Aggregation numbers (NAg) of micelles of the commercial anionic detergent sodium lauryl ether sulfate (SLES), with an average of two ethylene oxide subunits, were determined at 30 and 40o C by the time-resolved fluorescence quenching method with pyrene as the fluorescent probe and the N-hexadecylpyridinium ion as the quencher. The added-salt dependent growth of SLES micelles (γ = 0.11-0.15, where γ is the slope of a plot of log aggregation number vs. log [Yaq] and [Yaq] is the sodium counterion concentration free in the intermicellar aqueous phase) is found to be significantly lower than that of sodium alkyl sulfate micelles (γ ca. 0.25), a difference attributed to the larger headgroup size of SLES. The I1/I3 vibronic intensity ratio and the rate constant for intramicellar quenching of pyrene show that the pyrene solubilization microenvironment and the intramicellar microviscosity are insensitive to micelle size or the presence of added salt.

A blend of Sodium Humate/SLES/Herbal Oils

A blend of sodium humate (SH) with anionic surfactants such as sodium lauryl ether sulfate (SLES) was prepared by solution mixing at medium of herbal oils at 25, 50 and 75°C. Its miscibility studies were carried out by using physical techniques over an extended range of concentration and composition in buffer solution. In addition, to ascertain the state of miscibility of the blends, they were investigated by using UV-visible spectrophotometer and Fourier transform infrared (FTIR). These values revealed that the blend is miscible when the sodium humate content is more than %60 in the blend at all temperatures. There were no important differences in the characteristics of the blends at different temperatures. It was thought that the mechanism of the complex formation is realized by making strong intermolecular interaction like hydrogen bonds between the carbonyl groups in humic acid and hydroxyl groups in fatty acids.

Viscoelasticity of anionic wormlike micelles: effects of ionic strength and small hydrophobic molecules

The impact of NaCl and small hydrophobic molecules, used in perfumery, on the viscoelastic properties of aqueous solutions of sodium lauryl ether sulphate is studied. As the salt concentration increases, the viscosity passes through a maximum. Empirically, this behaviour is well known and is referred to as the ‘salt curve’. Dynamic rheological measurements revealed a detailed picture of how salt affects the different length scales in the entangled wormlike micelles. Adding hydrophobic molecules does not change the shape of the salt curve, but they can shift the maximum to lower salt concentrations and alter the peak viscosity. The shift in the salt curve can generally be understood as due to either flattening of the interface, caused by insertion of amphiphilic molecules into the surfactant layer, or micellar swelling, caused by solubilization of very hydrophobic molecules in the micellar core. The viscosity decrease at the salt curve maximum is inversely proportional to the hydrophobicity of the added molecules, so less hydrophobic compounds cause larger decreases. It is hypothesized that these molecules interact with the surfactant headgroups and thereby soften the interfacial film. Our analysis suggests that the addition of hydrophobic additives reduces the persistence length and results in an effective shortening of the micelles.

Surface acoustic wave based analytical system for the detection of liquid detergents

A novel analytical sensing system has been designed for the characterization and discrimination of different detergents in water. This micro-sensor system could play a key role in the development of more efficient and environmentally-friendly washing machines by enabling the measurement of residual detergents. The sensing system comprises a dual shear-horizontal surface acoustic wave (SH-SAW) resonator sensor housed within a poly-dimethylsiloxane (PDMS) microfluidic chamber. Free and electrically shorted SAW designs were used to analyze synthetic samples of liquid detergents with varying concentrations. Two anionic surfactants, namely sodium dodecylbenzene sulfonate and sodium laureth sulphate, and one non-ionic surfactant, polyoxyethylene (9.5) t-octylphenol have been studied. Dilution tests have been performed in order to determine the sensitivity or detection limit of this liquid sensing system and have been found to be ca. 10 ppm. The SAW based sensor system correctly classified all three detergents through the use of the transient signal response. Because the sensor operates without the need for a selective chemical or biological coating, it should be both robust and reliable. We believe that such technology could be used to make environmentally-friendly and greener washing machines by minimizing the use of detergents and hot water.

Effects of temperature, surfactants and skin location on the dermal penetration of haloacetonitriles and chloral hydrate

Dermal exposure has been recognized as an important contributor to the total internal dose to disinfection-by-products (DBPs) in water. However, the effect of the use of surfactants, water temperature and area of the body exposed to DBPs on their dermal flux has not been characterized and was the focus of the present study using an in-vitro system. The dermal flux of mg/l concentrations of haloacetonitriles and chloral hydrate (CH), important cytotoxic DBPs, increased by approximately 50% to 170% with increasing temperature from 25 °C to 40 °C. The fluxes for the torso and dorsum of the hand were much higher than that of palm and scalp skin. An increase in flux was observed for chloroacetonitrite and dichloroacetonitrile, two less lipophilic HANs, but not for trichloroacetonitrile or CH, with the addition of 2% sodium lauryl sulfate or 2% sodium laureth sulfate, two surfactants commonly used in soaps and shampoos used in showering and bathing. Thus, factors such as temperature, surfactants and skin location affect dermal penetration and should be considered when evaluating dermal absorption.

Growth inhibition and stimulation of Shewanella oneidensis MR-1 by surfactants and calcium polysulfide

Foam delivery technology (FDT) uses surfactant based foam to immobilize subsurface contaminants in situ. Where traditional approaches are impractical, FDT has the potential to overcome many of the technical challenges facing the remediation of contaminated deep vadose zone environments. However, little is known about the effects these reactive chemicals may have on microorganisms inhabiting the contaminated subsurface. In addition, there are currently no standard assays to assess microbial responses to subsurface remedial treatments while these agents are under development. The objective of this study was to develop a rapid laboratory assay to assess the potential growth inhibition and/or stimulation of microorganisms following exposure to candidate FDT components. Calcium polysulfide (CPS) and several surfactants (i.e. sodium laureth sulfate (SLES), sodium dodecyl sulfate (SDS), cocamidopropyl betaine (CAPB) and NINOL40-CO) have diverse chemistries and are candidate components of FDT. Shewanella oneidensis MR-1 cultures were exposed to a range of concentrations of these chemicals to determine the minimum bactericidal concentration (MBC) and the growth and viability potential of these components. Concentrations of SDS higher than 700μM were toxic to S. oneidensis MR-1 growth over the course of four days of exposure. The relative acute toxicity order for these compounds was SDS⪢CPS⪢NINOL 40-CO>SLES≥CAPB. Dose dependent growth decreases (20–100mM) were observed in the CAPB and SLES treated cultures and both CPS and NINOL 40-CO were toxic at all concentrations tested (1.45–7.25mM CPS). Both SLES (20–100mM) and SDS at lower concentrations (20–500μM) were stimulatory to S. oneidensis MR-1 indicating a capacity to be used as a carbon source. These studies also identified potentially key component characteristics, such as precipitate formation and oxygen availability, which may prove valuable in assessing the response of subsurface microorganisms. This benchtop system provides a capability to assess adverse microbial-remediation responses and contributes to the development of in situ remedial chemistries before they are deployed in the field.

Foam Consolidation and Drainage

A theoretical model of foam as a consolidating continuum is proposed. The general model is applied to foam in a gravity settler. It is predicted that liquid drainage from foam in a gravity settler begins with a slow drainage stage. Next, a stage with faster drainage occurs where the drainage rate doubles compared to the initial stage. The experiments conducted within the framework of this work confirmed the theoretical predictions and allowed measurements of foam characteristics. Foams of three different concentrations of Pantene Pro-V Classic Care Solutions shampoo were studied, as well as the addition of polyethylene oxide (PEO) in one case. The shampoo's main foaming components are sodium lauryl sulfate and sodium laureth sulfate. It is shown to what extent foam drainage is slowed down by using higher shampoo concentrations and how it is further decreased by adding polymer (PEO).

A New Aluminium Hydroxide Coating on Fused Silica Fiber for the Determination of 1,4-Dioxane in Surfactants and Detergents Using HS-SPME-GC

This paper presents a simple and convenient analytical method for determination of 1,4-dioxane in surfactants and detergents by using a novel SPME fiber. For the preparation of the fiber, the surface of a fused silica capillary tubing was modified by means of aluminium tri-tert-butoxide in a straightforward grafting process. The surface of our proposed fiber provides a Lewis acid–base interaction with analyte functional groups. The main factors affecting the extraction were optimized by using a central composite design method, which leads to the following optimum conditions: extraction temperature of 34 °C, extraction time of 4 min, equilibrium time of 13 min, and salt content of 25% (w/v). The optimum conditions showed a linear range from 0.005 to 60 μg g−1. LOD and LOQ of the proposed method were estimated to be 0.0015 and 0.005 μg g−1, respectively. This method was also applied for the analysis of some real samples including ethoxylated fatty alcohol, sodium lauryl ether sulfate, dish-washing agents, and shampoos by using the standard addition method.