Sodium Lauryl Ether Sulfate Research Articles

Degradation of anionic surfactants by Citrobacter braakii

Anionic surfactants, as core components of detergent and cosmetic products formulations, contribute significantly to the pollution profile of sewage and wastewaters of all kinds. In Tunisia more than 100 000 m 3 per year of surfactant containing wastewater are released. Treatment by conventional processes such as activated sludge is problematic due to the low kinetics of degradation by unsuitable consortia and to foam production. Bioremediation involves the isolation of suitable microorganisms, adequate process development and in situ biodegradation. The objective of this work was to develop a high performance process for the treatment of anionic surfactant containing wastewater. Screening of bacteria degrading the anionic surfactant sodium lauryl ether sulfate (SLES) was carried out by a conventional enrichment-culture technique. A Citrobacter braakii strain degrading many anionic surfactants was isolated and tested in bioaugmentation for industrial wastewater treatment. It was used for the continuous degradation of highly concentrated SLES synthetic medium and cosmetic industry wastewater. By testing several dilution rates, it was concluded that C. braakii is able to degrade up to 0.065 g l −1 h −1. The hydraulic retention time (HRT) was nearly 20 h. This process was improved by coupling the bioreactor to a mineral microfiltration membrane. This allowed an increase in the SLES elimination rate from 0.065 to 0.15 g l −1 h −1 and to reduce the HRT from 20 to 5 h. Moreover, this integrated system generates microorganism and surfactant free wastewaters able to be rejected without public menace or reused in situ in the industrial process.

Decalcifying effect of EDTA-T, 10% citric acid, and 17% EDTA on root canal dentin.

An in vitro study was conducted to determine the efficacy of 17% EDTA plus 1.25% sodium lauryl ether sulfate (EDTA-T), 10% citric acid, and 17% EDTA with respect to Ca(++) extraction. The root canals of 90 extracted human canines were instrumented by using the step-back technique. The teeth were randomly divided into 9 groups of 10 teeth each according to the solution and time intervals involved (ie, 3, 10, and 15 minutes). The Ca(++) concentration of the solution was determined by using atomic absorption spectroscopy. At 3 minutes, there was no significant difference between Ca(++) extraction by 10% citric acid and 17% EDTA (P >.05). EDTA-T had the least efficacy for Ca(++) extraction (P <.05). At 10 minutes and 15 minutes, there were no significant differences between 10% citric acid and 17% EDTA or between EDTA-T and 17% EDTA (P >.05). However, 10% citric acid was significantly better than EDTA-T in terms of Ca(++) extraction (P <.05). Both 10% citric acid and 17% EDTA are good decalcifying agents when the step-back technique is used.

Adsorption of Sodium Lauryl Ether Sulfate on Liposomes by Means of a Fluorescent Probe: Effect of the Ethylene Oxide Groups

Adsorption of Sodium Lauryl Ether Sulfate on Liposomes by Means of a Fluorescent Probe: Effect of the Ethylene Oxide Groups

Study of surfactant—liposome interactions at sublytic level by means of a surface probe

The incorporation of the sodium lauryl ether sulfate (SLES) on phosphatidylcholine (PC) liposomes has been studied with time using the fluorescent probe 2‐(p‐toluidinyl)‐naphthalene‐6‐sodium sulfonate (TNS). This probe reports changes on the surface potential of PC liposomes by effect of the anionic surfactant adsorption. The addition of small SLES amounts promoted an abrupt fall in the fluorescence intensity (F.I.) and this fall was already detected 10 secs after mixing. Only slight changes with time were observed in the F.I. of SLES—liposome‐probe systems. These results indicate a fast and almost complete incorporation of SLES on the liposome surface. The surfactant/lipid molar ratios (Re) and the surfactant partition coefficients bilayer/aqueous phase (K) were determined from the linear dependence between lipid and surfactant concentrations obtained for a fixed number of surfactant molecules on the liposome surface. The Re values indicated that the highest SLES ability to adsorb on the surface occurs at the initial adsorption moments. The K values indicated that the affinity of the surfactant by the liposomes decreased after about 7500 surfactant molecules were adsorbed on the bilayer. This fact is probably caused by the increase of electrostatic repulsion between surfactant monomers in the bulk solution and the bound surfactant. The aforementioned linear dependence obtained from the data for a given number of SLES molecules on the bilayer and the range of SLES concentrations used (below/above its critical micelle concentration, CMC) suggest an adsorption mechanism regardless of the surfactant concentration: a monomeric adsorption of SLES is always assumed in both above/below surfactant CMC. In comparison with the higher adsorption reported for the analogous sodium dodecyl sulfate, the ethylene oxide moles in SLES could hinder its incorporation on PC liposomes. Thus, this study of sublytic interactions allows to follow the incorporation of surfactants on the lipid bilayers and to compare the effect of different surfactants on the membranes before the lysis.

The influence of additive molecular weight and ionic nature on the pool boiling performance of aqueous surfactant solutions

Saturated nucleate pool boiling on a horizontal cylindrical heater in aqueous solutions of surfactants, which have different molecular weights and ionic character, has been experimentally investigated. Two anionic surfactants, sodium dodecyl sulphate (SDS) and sodium lauryl ether sulfate (SLES), and two nonionic surfactants, Triton X-100 and Triton X-305, were used; their molecular weights are 288.3, 422, 624 and 1526, respectively. The boiling performance, characterized by an early onset of nucleate boiling, is significantly enhanced, and the maximum enhancement increases with decreasing surfactant molecular weight. Also, the heat transfer coefficient, normalized by dynamic σ (at 50 ms, 80°C), scales as h∝ M n with n=−0.5 and 0 for anionics and nonionics, respectively. This scaling follows from the postulation that the solution's dynamic surface tension is determined by the surfactant concentration and its interfacial activity in the sublayer around the growing bubble. Correspondingly, boiling of these solutions is directly influenced by the ionic character and molecular makeup of this sublayer.

Adsorption of an anionic dispersant on lignite

Since coal is not a homogeneous substance but a mixture of carbonaceous materials and mineral matter, it has a variety of surface properties. Therefore, it is not easy to control the properties of coal suspensions by simply adjusting variables, such as pH and/or electrolyte. A chemical agent needs to be added to control the properties of the coal suspensions. The aim of this investigation is to determine the adsorption behavior of an anionic dispersant in the presence of a wetting agent using some Turkish lignite samples. The presence of a wetting agent in the dispersant adsorption behavior is important, since usage of a wetting agent in the preparation of coal–water slurries which are acceptable for potential industrial users is of great importance. The effects of dispersant concentration, temperature and pH on the dispersant adsorption were studied systematically, and the experimental results are presented. Pellupur B69 as a dispersant, commercial mixture of formaldehyde condensate sodium salt of naphthalene sulphonic acid, and Texapon N25 as a wetting agent, a sodium lauryl ether sulfate, have been used.

Subclinical, non-erythematous irritation with an open assay model (washing): sodium lauryl sulfate (SLS) versus sodium laureth sulfate (SLES)

Compared to exaggerated hand washing procedures, an open non-exaggerated assay better approximates consumer surfactant use. Our goal was to observe skin surface modifications induced by an open test with regard to discriminating between surfactant solutions. This human in vivo assay provided information about the effect of only three washes at the laboratory and a week of at-home use. Dorsal hand and volar forearm were compared. The results demonstrated that this clinical model permits exploration of subclinical surfactant-induced irritation. Both the volar forearm and the dorsal hand are capable of discriminating between the effects of sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES). Squamometry proved to be a sensitive assessment technique for detecting surfactant-induced subclinical skin surface alterations and for differentiating surfactant effects in this open application assay, in as few as three washes.

Dynamic Properties of Entangled Wormlike Micelles: Sodium Laurylethersulfate at High Ionic Strength-(II)

We report on the viscous behaviour of long and flexible wormlike micelles at volume fractions between Ø = 0.05–0.14 comprised of sodium laurylethersulfate (SLES) in 0.15–0.5 M NaCl equivalent of SLES concentrations between 20–50 mM at temperatures ranging from 25 °C to 45 °C by means of static and dynamic light scattering and rheology, which is an extension of previous experiments on dilute/semi-dilute solutions of SLES micelles at much lower surfactant concentrations in the presence of low salt concentrations (Clancy and Paradies, Z. Phys. Chem.

Structure, Diffusivity and Linear Rheology of Sodium Ether Dodecylsulfate in Aqueous Solutions – (I)

Static and dynamic light scattering measurements have been performed on dilute and semidilute solutions of sodium ether dodecylsulfate (sodium laurylethersulfate, RO(CH

Determination of anionic surfactants during wastewater recycling process by ion pair chromatography with suppressed conductivity detection

A direct approach utilizing ion pairing reversed-phase chromatography coupled with suppressed conductivity detection was developed to monitor biodegradation of anionic surfactants during wastewater recycling through hydroponic plant growth systems and fixed-film bioreactors. Samples of hydroponic nutrient solution and bioreactor effluent with high concentrations (up to 120 mS electrical conductance) of inorganic ions can be analyzed without pretreatment or interference. The presence of non-ionic surfactants did not significantly affect the analysis. Dynamic linear ranges for tested surfactants [Igepon TC-42, ammonium lauryl sulfate, sodium laureth sulfate and sodium alkyl (C 10–C 16) ether sulfate] were 2∼500, 1∼500, 2.5∼550 and 3.0∼630 μg/ml, respectively.

Conditioning polymers in today’s shampoo formulations – efficacy, mechanism and test methods

Today's shampoo formulations are beyond the stage of pure cleansing of the hair. Additional benefits are expected, e.g. conditioning, smoothing of the hair surface, improvement of combability and lather creaminess. Cationic polymers play an important role in providing many of those features. Therefore, within the last few years their use in shampoos has increased greatly. In the only last two decades, shampoo designation has gradually changed from '2-in-1' to '3-in-1' and then to 'multifunctional', as at present. The consumer demands products which live up to their promises. Modern shampoos contain a wide variety of ingredients such as co-surfactants, vitamins and pro-vitamins, protein derivatives, silicones, natural-based plant extracts and other 'active ingredients', but there is still a need for conditioning polymers. The specific objective of this study is to assess the conditioning efficacy of cationic polymers and to investigate their mechanisms in a shampoo system. The investigations were carried out on formulations that contained sodium lauryl ether sulphate and different cationic polymers, e.g. Polyquaternium 7, 10, 11, cationic guar gum and Luviquat Care (Polyquaternium 44), a new branched copolymer of vinylpyrrolidone (VP) and quaternized vinylimidazolium salts (QVI). We used test methods relevant to the applications in question, such as combing force measurements, the feel of the hair and the creaminess of the lather, to assess the efficacy. Atomic force microscopy and electrokinetics (streaming potential) were used to detect polymer residues on treated hair. All the polymers under investigation improved the overall performance of the shampoo formulations. This was demonstrated by means of combing force measurements, sensorial tests and analytical methods, namely zeta potential measurement and atomic force microscopy. Polyquaternium 44 exhibited the best conditioning properties on wet hair without sacrificing removability or absence of build-up. The latter are the most striking weaknesses of cationic Guar Gum-based polymers. Polyquaternium 10 can also be removed from the hair after rinsing with anionic surfactant but it does not perform as well as Polyquaternium 44 in the fields of wet combability and sensorial criteria such as lather creaminess and feel of the hair. We postulate that the outstanding properties of Polyquaternium 44 as a conditioning agent for shampoos are due to its tailor-made 'branched' structure. There is a clear correlation between the molecular weight and the efficacy of the new copolymers of VP and QVI. Only cationic polymers with a very high molecular weight are effective as conditioners in shampoos based on anionic surfactants. Surprisingly, they do not have to have a high cationic charge. On the basis of all our results, our postulation is that the polymer residue which is responsible for conditioning does not form a flat layer on the hair. Rather, the polymer residue adsorbs with the few cationic moieties, while the uncharged part of the polymer forms loops, which are orientated away from the hair and which are responsible for the reduced friction between hairs.

Evaluation of the irritant capacity of decyl polyglucoside

The irritant capacity of several anionic, amphoteric and non-ionic surfactants has been studied by non-invasive techniques, specifically by evaporimetry, laser Doppler flowmetry and one-dimensional cutaneous ecography. Some of the surfactants most frequently used in shampoos and shower/foam gels were selected for testing. A series of aqueous solutions containing 5% of the active material in these products was patched onto normal skin; controls for comparison were set up with water and with sodium lauryl sulphate (SLS), a recognized irritant standard substance. It was deduced from the results obtained that, of the surfactants tested, the one showing the lowest irritant capacity is decyl polyglucoside, followed in increasing order of irritant capacity, by cocoamidopropyl betaine, magnesium laurylether sulphate and sodium laurylether sulphate.

Evaulation of Irritation Potential of Surfactant Mixtures

Irritation potential of sodium laureth sulfate (SLES) alone, and in combination with lauryl glucoside (LG), polysorbate 20 (PS) and cocoamidopropyl betaine (CAPB) was tested in 13 human subjects. Four main and six sub-formulations were prepared and evaluated. Formulations were applied to the forearm as a 24 h close patch study. Irritation was scored by two different methods using an in vivo clinical protocol based on visual scoring and on the stratum corneum capacitance measurement. Irritation was found to be dose dependent. At 2 mg/patch level ten subjects did not show any skin reaction. At 20 mg/patch level eleven subjects showed a broad range of skin irritation. The highest irritation was observed with the formula that contained SLES, LG, and cocamide DEA together. Among the sub-formulations, cocamide DEA showed the highest irritation grade. A statistically significant correlation was observed between visual, clinical and corneometer scores. It was concluded that the irritation potential of surfactants was related to the total surfactant concentration, application mode, and the thermodynamic activity of molecules in the solution as well as the chemical structure of the surfactant molecules.

Foaming and emulsifying properties of soy protein isolate and hydrolysates in skin and hair care products

AbstractThere is a growing market for formulating proteins into a wide variety of products including laundry detergents, bath products, shampoos, and skin cleansers. Soy protein isolate (SPI), soy protein hydrolysate A (SPHA) from papainmodified SPI, and hydrolysate B from papain‐ and proteasemodified SPI were used in blends with three major detergents, sodium dodecyl sulfate (SDS), sodium laureth sulfate (SLS), and disodium lauryl sulfosuccinate (DSLSS). SPHA was used to partially replace these detergents in bath soap, conditioning shampoo, and cream hand cleanser. The effectiveness of SPI, SPHA, or SPHB blends with the three detergents and their influence in prototype products on foaming and emulsifying properties were investigated.At a blending ratio of 75% detergents and 25% proteins (75∶25), the foaming capacities (FC) were the same as detergents alone without adding proteins (100∶0); at 50∶50 blending ratio, FC values were not significantly reduced for blends with SDS and SLS; and at 25∶75 ratio the FC values were significantly lower, especially for blends with DSLSS. When replacing up to 100% of the major detergents in the skin and hair care products with SPHA, FC values remained almost unchanged except for hand cleanser FC values, which were lower at higher protein content (75 and 100%). In contrast with FC performance, emulsion stability (ES) values for all products increased with increasing soy protein content. Furthermore, FC and ES values for detergents blended with SPHA or SPHB were not significantly different from each other, but these values were always higher than those for detergents blended with SPI. Products in which soy protein or soy protein hydrolysates were used to partially replace detergents not only retained excellent foaming properties but also exhibited enhanced emulsifying properties. These results indicate that modified soy proteins may be used in laundry and cosmetic products to fulfill market demand.

The effects of surfactants on the biosynthesis of galactolipid and the composition of fatty acids in chloroplast envelope and thylakoid membrane ofchlorella ellipsoidea

To analyze the effects of surfactants on the biosynthesis of galactolipid and the composition of fatty acids, the chloroplast envelope and thylakoid membrane were cultivated in medium treated with anionic surfactants, such as linear alkylbenzene sulfonate (0.002%, LAS), α‐olefin sulfonate (0.01%, AOS), and sodium lauryl ether sulfate (0.08%, SLES), respectively. During the cultivation, the chloroplast envelope and thylakoid membrane were isolated from the cells collected at the early and middle phase of the culture and the contents of their fatty acid composition were compared with the control. When treated with surfactants, the contents of total lipid, MDGD methylesters, and DGDG methylesters decreased significantly when compared with the control. It was also confirmed that more unsaturated fatty acids were involved in the biosynthesis of galactolipid. The fatty acids utilized in the biosynthesis of MGDG were in the chloroplast envelope and in the control, and linoleic acid in LAS, linolenic acid and ole...

Protein/surfactant interfacial interactions Part 3. Competitive adsorption of protein + surfactant in emulsions

We present results of competitive adsorption between proteins and surfactant (nonionic Tween 20 or anionic sodium lauryl ether sulphate SLES 2EO) in various oil-in-water emulsions. The addition of gelatin to a β-lactoglobulin-stabilized emulsion results in secondary layer adsorption of gelatin. The condition of half-coverage of gelatin correlates with the maximum degree of bridging flocculation. The amount of nonionic surfactant (Tween 20) required for complete displacement of gelatin from the oil/water interface is found to be higher than that required for displacement of β-lactoglobulin. The mixed proteins are less easy for the nonionic surfactant to displace from the oil/water interface. The addition of anionic surfactant (SLES 2EO) to a gelatin-stabilized emulsion leads to co-operative adsorption as well as competitive adsorption. The co-operative adsorption induces a higher gelatin surface concentration which correlates with enhanced emulsion flocculation. In emulsions containing the mixed proteins (β-lactoglobulin+gelatin), added anionic surfactant SLES 2EO is unable to displace proteins completely from the droplet surfaces and the protein surface concentration behaviour shows a consistent trend to that found in separate emulsion flocculation studies.

Protein/surfactant interfacial interactions paet 2. Electrophoretic mobility of mixed protein + surfactant systems

Protein-protein and protein-surfactant interactions have been investigated in bulk aqueous solution and in oil-in-water emulsion systems by electrophoretic mobility measurements. The interaction between oppositely charged β-lactoglobulin and gelatin has been studied under neutral pH conditions. The addition of cationic gelatin to a β-lactoglobulin-stabilized emulsion induces flocculation and charge neutralization of the emulsion droplets. The procedure of mixing the gelatin solution with the β-lactoglobulin-stabilized emulsion has no significant effect on the observed mobility behaviour of the emulsion droplets. Binding of the anionic surfactant sodium lauryl ether sulphate (SLES 2EO) to β-lactoglobulin and gelatin was observed under neutral pH conditions. The charge neutralization line for gelatin + SLES 2EO complexes in distilled water appears consistent with its maximum precipitation line. However, the charge neutralization line of gelatin + SLES 2EO at pH 7.0 occurs at slightly lower surfactant concentrations compared to the maximum precipitation line. The addition of SLES 2EO to a gelatin-stabilized emulsion causes a change in calculated zeta potential of the emulsion droplets and a partial charge neutralization for the flocculated emulsion droplets. Electrophoretic mobility measured in solutions of β-lactoglobulin + gelatin + SLES 2EO shows that the three-component complexes (or precipitates) are negatively charged. Various possible interaction mechanisms are discussed taking account also of results obtained on the same systems by other complementary techniques.

Protein/surfactant interfacial interactions part 1. Flocculation of emulsions containing mixed protein + surfactant

The effect of interactions of positively charged gelatin and anionic surfactant sodium lauryl ether sulphate (SLES 2EO) with negatively charged β-lactoglobulin in solutions and emulsions has been studied. Precipitation was observed in solution for a gelatin + SLES 2EO mixture with and without β-lactoglobulin. The precipitation concentrations of gelatin and SLES 2EO were found to be strongly dependent on the bulk pH conditions and whether β-lactoglobulin was present. The introduction of SLES 2EO to a gelatin-stabilized emulsion induces destabilization followed by restabilization. The optimum surfactant concentration for the maximum degree of flocculation was found to be much higher than that for maximum precipitation of the corresponding mixture in bulk aqueous solution. Different extents of flocculation were observed when a certain amount of gelatin or gelatin + SLES 2EO was added to a 0.4 wt.%, β-lactoglobulin-stabilized emulsion. Higher gelatin and SLES 2EO concentrations can cause the flocculated emulsion to become restabilized. The character of the interfacial protein surfactant interactions are therefore found to be different in nature from those in the bulk aqueous phase. A bridging mechanism and a cross-linking mechanism were separately suggested to explain the types of flocculation induced by two different kinds of interactions. The effects on the flocculation of changing the temperature, incorporating oil-soluble surfactant, and adjusting the procedure, have been investigated. The present results are discussed in the light of other experimental results obtained on the same systems by complementary techniques.

Surface shear viscosity and protein-surfactant interactions in mixed protein films adsorbed at the oil-water interface

The surface shear viscosity of protein films adsorbed from pure or mixed β-lactoglobulin + cationic gelatin aqueous phases have been studied at the n-hexadecane—water interface (5 mmol/ dm 3 bis-tris-propane buffer, pH 7.0, 2 × 10 −3 wt% protein). The effect of the introduction of nonionic surfactant Tween 20 (polyoxyethylene (20) sorbitan monolaurate) and anionic surfactant SLES 2EO (sodium lauryl ether sulphate) into the subphase below the 1-day-old pure or mixed protein films has been investigated. The addition of Tween 20 to individual β-lactoglobulin or gelatin films brings the surface viscosity rapidly down to zero, but not so for the mixed β-lactoglobulin + gelatin film. The addition of SLES 2EO to the gelatin film produces a molecular rearrangement and a gradual decrease of the surface viscosity. The effect of oil-soluble surfactant C 12E 2 (diethylene glycol monododecyl ether) on the surface shear viscosity of adsorbed β-lactoglobulin has been studied. A small amount of C 12E 2 induces a large increase in surface viscosity. Synergistic adsorption effects are proposed between the oppositely charged β-lactoglobulin and gelatin molecules and between the oil-soluble surfactant C 12E 2 and the β-lactoglobulin molecules.

Evaluation of predictable irritative power of surfactant mixtures by human fibroblast culture and its correlation to physico‐chemical parameters

Summary The predictable toxic effects of some surfactants, their blends and some preserving agents on human fibroblast cultures were investigated with in vitro tests, with the aim of finding a possible correlation between the biologic evaluations and some physical characteristics of detergent solutions. Lactate dehydrogenase release into the medium was used as a marker of the plasma membrane integrity, while the amount of (3)H-radiolabelled proteins in the fibroblasts was measured in order to assess the cell biosynthetic machinery function. Disodium-alkyl-semi-sulphosuccinate induced membrane damage in the lactate dehydrogenase test and decreased the protein synthesis, with an EC 50 around 1mm, while sodium lauryl ether sulphate had an EC 50 at about 100 mum, indicating that this compound is ten-fold more toxic, when measured by this method. An ethoxylated glyceride, on the contrary, was completely harmless on the plasma membrane and, surprisingly, activated fibroblast protein synthesis in a dose-response way up to two-fold. Mixtures of the three surfactants evidenced the protective effect of the non-ionic against the cellular functionality damage. Parabens do not influence this type of evaluation, while some influence was shown by the formaldehyde releaser 2-bromo-2-nitro-propandiol at the highest concentration. The comparison between critical micellar concentration measures of the different surfactants and their in vitro detected irritative power shows, for the two anionics, that in vitro toxicity is proportionally bound to the amount of micelles even if the structural differences between the two types of molecules are reflected into different damage values, while the non-ionic compound shows a not defined CMC and a very low toxicity profile. Blends of anionics with the non-ionic show an increased CMC and a reduced toxicity profile. Toxicity evaluations of complex finished foaming formulations, carried out with human fibroblast cultures evaluation show that a relationship between micelles amount and cell toxicity seems to exist, mainly when multiple surfactants blends are tested.