Sodium Lauryl Ether Sulfate Research Articles

Study on car shampoo formulation using D-optimal statistical design

In this investigation car shampoo formulation was studied. The quality of car shampoo is directly linked to the basic material used in the formulation. By varying the ratio of ingredients such as sodium metasilicate (SMS), sodium lauryl ether sulphate (SLES), coco dimethyl betaine (betaine), coconut fatty acid diethanolamide (CDE) and linear alkyl benzene sulphonate (LABS), the final product characteristics were determined. A common problem in pre-formulation is the optimization of the mixture composition which is aimed to obtain a product with the required characteristics. In this work, various composition surfactants were used to prepare the car shampoo formulations. The D-optimal mixture design was performed to obtain the optimum formulation. Twenty-five combination components were selected according to the D-optimal criterion. Physical properties of the car shampoo such as pH, power of removal and foaming ability were studied. Contour graphics were formed to assess the change in the response surface in order to understand the effect of the mixture composition on car shampoo characteristics. The statistical study shows that the fitted model was adequate to describe the viscosity response. The optimum composition formulation was SMS 1.48%, SLES 3.52%, betaine 4.0%, CDE 4.5% and LABS 1.5%.

Solubility limits and phase diagrams for fatty acids in anionic (SLES) and zwitterionic (CAPB) micellar surfactant solutions

The limiting solubility of fatty acids in micellar solutions of the anionic surfactant sodium laurylethersulfate (SLES) and the zwitterionic surfactant cocamidopropyl betaine (CAPB) is experimentally determined. Saturated straight-chain fatty acids with n=10, 12, 14, 16, and 18 carbon atoms were investigated at working temperatures of 25, 30, 35, and 40°C. The rise of the fatty acid molar fraction in the micelles is accompanied by an increase in the equilibrium concentration of acid monomers in the aqueous phase. Theoretically, the solubility limit is explained with the precipitation of fatty acid crystallites when the monomer concentration reaches the solubility limit of the acid in pure water. In agreement with theory, the experiment shows that the solubility limit is proportional to the surfactant concentration. For ideal mixtures, the plot of the log of solubility limit vs. the chainlength, n, must be a straight line, which is fulfilled for n=14, 16, and 18. For the fatty acids of shorter chains, n=10 and 12, a deviation from linearity is observed, which is interpreted as non-ideal mixing due to a mismatch between the chainlengths of the surfactant and acid. The data analysis yields the solubilization energy and the interaction parameter for the fatty acid molecules in surfactant micelles. By using the determined parameter values, phase diagrams of the investigated mixed solutions are constructed. The four inter-domain boundary lines intersect in a quadruple point, whose coordinates have been determined. The results can be applied for the interpretation and prediction of the solubility, and phase behavior of medium- and long-chain fatty acids and other amphiphiles that are solubilizable in micellar surfactant solutions, as well as for determining the critical micellization concentration (CMC) of the respective mixed solution.

Cellular Toxicity of Surfactants Used as Herbicide Additives

The cellular toxicities of surfactants, a solvent, and an antifreeze that are included in herbicide formulations were assessed by measuring their effects on membrane integrity, metabolic activity, mitochondrial activity, and total protein synthesis rate in a cell culture. Polyethylene glycol, propylene glycol, and monoethylene glycol exhibited no cellular toxicity even at a high concentration of 100 mM. Sodium lauryl ether sulfate and polyoxyethylene lauryl ether significantly damaged the membrane, disturbed cellular metabolic activity, and decreased mitochondrial activity and the protein synthesis rate; however, their toxicity was far below those of the severely toxic chemicals at comparable concentrations. The severely toxic category included polyoxypropylene glycol block copolymer, polyoxyethylene tallow amine, and polyoxyethylene lauryl amine ether. These surfactants were cytotoxic between 3.125 µM and 100 µM in a dose-dependent manner. However, the toxicity graph of concentration vs toxicity had a point of inflection at 25 µM. The slope of the toxicity graph was gentle when the concentration was below 25 µM and steep when the concentration was greater than 25 µM. In conclusion, our results suggest that the toxicity of surfactants be taken care of pertinent treatment of acute herbicide intoxication.

Interactions between selected bile salts and Triton X-100 or sodium lauryl ether sulfate

BackgroundIn order to develop colloidal drug carriers with desired properties, it is important to determine physico-chemical characteristics of these systems. Bile salt mixed micelles are extensively studied as novel drug delivery systems. The objective of the present investigation is to develop and characterize mixed micelles of nonionic (Triton X-100) or anionic (sodium lauryl ether sulfate) surfactant having oxyethylene groups in the polar head and following bile salts: cholate, deoxycholate and 7-oxodeoxycholate.ResultsThe micellization behaviour of binary anionic-nonionic and anionic-anionic surfactant mixtures was investigated by conductivity and surface tension measurements. The results of the study have been analyzed using Clint's, Rubingh's, and Motomura's theories for mixed binary systems. The negative values of the interaction parameter indicate synergism between micelle building units. It was noticed that Triton X-100 and sodium lauryl ether sulfate generate the weakest synergistic interactions with sodium deoxycholate, while 7-oxodeoxycholate creates the strongest attractive interaction with investigated co-surfactants.ConclusionIt was concluded that increased synergistic interactions can be attributed to the larger number of hydrophilic groups at α side of the bile salts. Additionally, 7-oxo group of 7-oxodeoxycholate enhance attractive interactions with selected co-surfactants more than 7-hydroxyl group of sodium cholate.

Long-chain anionic surfactants in aqueous solution. Removal by Moringa oleifera coagulant

Moringa oleifera seed extract was confirmed as a feasible coagulant in removing surfactants from aqueous effluents. Amongst them, long-chain anionic detergents such as Polyoxyethylene (3.5) sodium lauryl ether sulfate (SLES) was selected as a model compound for evaluating the coagulation response. The system coagulant–detergent was stable with different temperatures and pH, and the efficiency was very promising. M. oleifera was an effective coagulant since it was capable to reach up to 0.245 mg mg −1 coagulation capacity according to Gu–Zhu model. Design of experiments presented an optimum combination of coagulant dosage and initial surfactant concentration of 234 mg L −1 and 76 mg L −1, respectively.

MECHANICAL DEGRADATION OF HIGH MOLECULAR WEIGHT POLYMER WITH SURFACTANT ADDITION IN A ROTATING DISK APPARATUS

Mechanical degradation hampers the practical usage of polymers for turbulent drag reductionapplication. Mechanical degradation refers to the chemical process in which the activation energy ofpolymer chain scission is exceeded by mechanical action on the polymer chain, and bond ruptureoccurs. When a water-soluble polymer and surfactant are mixed in water solution, the specific structures(aggregates) are formed, in which polymer film is formed around micelle. In this work, Xanthan gum (XG) –Sodium lauryl ether sulfate (SELS) complex formation and its effect on percentage viscosity reduction(%VR) was studied. It was found that SELS surfactant reduced the mechanical degradation of XG muchmore efficiently than this polymer alone. Xanthan Gum (XG) has been tested for its shear stability anddegradability. 0.5% and 1.0 % by weight concentration solutions were exposed to shear stirring at differentspeeds and time; also 0.5% through 1.5% by weight concentration solutions of SELS were added to XGsolutions to determine the ability of SELS to reduce the mechanical degradation of XG. It has been noticedby measuring the percentage viscosity reduction (%VR) of the mixture of XG-SELS that the % VRdecreases when added this surfactant to XG polymer

Surfactant-assisted synthesis of bis(indolyl)methanes in water

Abstract An environmentally friendly synthesis method for bis(indolyl)methanes has been developed in the presence of sodium lauryl ether sulfate (SLES), electrophilic substitution reactions of indoles with aldehydes were accomplished in water as solvent at room temperature without any Bronested or Lewis acid catalysts.

Tratamento de Solo Contaminado com Petróleo Utilizando Tensoativos e Peróxido de Hidrogênio.

O processo de lavagem de solo com substâncias tensoativas, Lauril éter sulfato de sódio (LESS) e Lauril sulfato de sódio (SDS), foi combinado à oxidação química utilizando peróxido de hidrogênio, com vistas à remediação in situ de solo argiloso contaminado com hidrocarbonetos de petróleo. A avaliação da eficiência do processo baseou-se na remoção dos hidrocarbonetos poliaromáticos e na comparação das características físicas e químicas do solo contaminado e não-contaminado oriundos da mesma região. A combinação dessas duas técnicas, lavagem do solo e aplicação de agente oxidante, apresentou-se como processo de remediação eficaz para solos argilosos contaminados com derivados de petróleo em regiões subtropicais.

Formulation and assessment of the efficacy of a herbal shampoo containing lavender oil

Today considerable consumer interest has risen towards the use of herbal hygienic and cosmetic products. Lavender oil is a well-known essence with uses in the treatment of alopecia, dandruff and scalp hair re-growth, as well as possessing antimicrobial, antiviral and antifungal effects. Hence, this study was undertaken to formulate and assess the efficacy of a new clear liquid hair shampoo containing this essence. Initially, various concentrations of anionic, nonionic and amphoteric surfactants were examined to obtain a suitable and effective cleansing detergent base. Next, the necessary additives were incorporated into the detergent base to obtain the most desirable clear shampoo formulation. Finally, 0.5% lavender essence was included within the shampoo base and then the product underwent various physico-chemical tests as well as assessment of the efficacy and acceptability in twenty volunteers. Following extensive formulation, eventually a clear liquid shampoo containing triethanolaminelauryl sulfate and sodium laurylether sulfate (anionic detergents), coconut diethanolamide (foam builder, stabilizer and hair softener), poloxamer 407 and alkyldimethylaminobetaine (nonionic and amphoteric co-detergents for reducing eye and skin irritation), sodium chloride (viscosity adjusting agent), methyl and propyl paraben (preservatives), BHA (antioxidant), glycerin (conditioner), EDTA (sequestrant) and lavender oil was prepared. This formulation had a clear appearance, pleasant odor, good spreadability, substantivity and skin feel, and a pH of 7.05±0.07. It produced copious amounts of a rich, stable, and durable foam, with desirable washability following use. This shampoo formulation supported no microbial or fungal growth, and remained stable under thermal, mechanical and accelerated stability tests (at 40°C for 6 months). Finally, the efficacy (especially against dandruff), applicability and acceptability of this shampoo was justified and approved by twenty volunteers. The formulated lavender oil containing clear liquid shampoo appears to be a pleasant, acceptable and effective herbal product, particularly suitable against dandruff as well as hair and scalp hygiene.

Phase Behavior of an Extended Surfactant in Water and a Detailed Characterization of the Concentrated Phases

The formation of microemulsions with triglycerides at ambient conditions can be improved by increasing the surfactant-water and surfactant-oil interactions. Therefore, extended surfactants were developed, which contain hydrophilic/lipophilic linkers. They have the ability to stretch further into the oil and water phase and enhance the solubility of oil in water. In this work, the phase behavior of a chosen extended surfactant (C(12-14)-PO(16)-EO(2)-SO(4)Na, X-AES) in H(2)O/D(2)O at high surfactant concentrations (30-100 wt %) and at temperatures between 0 and 90 °C is studied for the first time. The lyotropic liquid crystals formed were determined by optical microscopy, small-angle X-ray scattering (SAXS), and (2)H and (23)Na NMR, and a detailed phase diagram of the concentrated area is given. The obtained mesophases are a hexagonal phase (H(1)), at low temperatures and small concentrations, a lamellar phase (L(α)) at high temperatures or concentrations, a bicontinuous cubic phase (V(2)) as well as a reverse hexagonal phase (H(2)). To our knowledge, this is the first surfactant that forms both H(1) and H(2) phases without the addition of a third compound. From the (2)H NMR quadrupole splittings of D(2)O, we have examined water binding in the L(α) and the H(2) phases. There is no marked difference in the bound water between the two phases. Where sufficient water is present, the number of bound water molecules per X-AES is estimated to be ca. 18 with only small changes at different temperatures. Similar results were obtained from the (23)Na NMR data, which again showed little difference in the ion binding between the L(α) and the H(2) phases. The X-ray diffraction data show that X-AES has a much smaller average length in the L(α) phase compared to the all-trans length than in the case for conventional surfactants. At very high surfactant concentrations an inverse isotropic solution (L(2)), containing a small fraction of solid particles, is formed. This isotropic solution is clearly identified and the size of the reversed micelles was determined using (1)H NMR measurements. Furthermore, the solid particles within the L(2) phase and the neat surfactant were analyzed. The observed results were compared to common conventional surfactants (e.g., sodium dodecyl sulfate, sodium lauryl ether sulfate, and sodium dodecyl-p-benzene sulfonate), and the influence of the hydrophilic/lipophilic linkers on the phase behavior was discussed.

Removing Highly Cohesive Silicone Gel after Breast Implant Rupture: An In Vitro Study

Sir: After breast implant rupture, the silicone gel must be removed thoroughly from surrounding tissues to prevent inflammatory reaction, granuloma formation, and possible local infection. The fourth generation of implants commonly used today contains highly cohesive silicone gel. We know little about its gel-dissolving qualities. This study sought to determine which of the commonly used operating room irrigation solutions is best for dissolving the highly cohesive silicone gel. Special attention was given to dimethyl sulfoxide solution because of its chemical1 and clinical antiinflammatory2,3 and anticollagenous4 properties. Gravimetry was used to test silicone gel solubility in dimethyl sulfoxide and other agents commonly used in the operating room, as follows: Normal saline (0.9% sodium chloride). Iodine solution 10%. Polydine scrub (7.5% povidone-iodine with sodium laureth sulfate, potassium iodide, and trisodium phosphate). Unisept (0.05% chlorhexidine gluconate in aqueous solution containing sodium hydroxide, nonoxynol 10, and carnosine red). Hydrogen peroxide 3%. Septal scrub (chlorhexidine gluconate 4%). Aliquots of the gel from a new silicone gel implant (Mentor Corp., Santa Barbara, Calif.) were spread onto glass microscope slides in incremental weights of 0.02, 0.04, 0.06, and 0.08 g. Each slide was soaked in 40 ml of solvent for 2 minutes, rinsed with 80 cc of deionized water for 30 seconds, and placed in a vacuum desiccator for 24 hours. The percentage reduction in silicone weight was calculated for each solvent. Experiments were repeated six times. Results were confirmed by gas chromatography. None of the solutions examined, including dimethyl sulfoxide, dissolved the silicone gel. By gravimetry, the postsolvent silicone gel weights were equal to or, in some cases, even higher than the presolvent weights. Chromatography failed to yield a peak that might have been explained by silicone gel solubility. This study sought to determine the ability of dimethyl sulfoxide and other irrigation solutions to serve as a solvent for breast implant silicone gel. We assumed that the unique chemical structure and high solvent qualities of dimethyl sulfoxide would make it a good candidate agent for cleaning the breast pocket after implant rupture. Moreover, dimethyl sulfoxide, because of its proven clinical properties, such as maintenance of lysosomal integrity, inhibition of fibroblast proliferation, and antibacterial action, could have added value by decreasing capsular contracture and infection rates. Using both gravimetry and gas chromatography, we found that dimethyl sulfoxide, like all the other solutions studied, was ineffective in dissolving the highly cohesive silicone gel. Our findings disagree with those of Bitar et al.5 for saline and iodine solutions. The discrepancy in the results might be attributed to changes made in the cohesiveness of the gel in the interim between the two studies. The new, highly cohesive, silicone gel is difficult to dissolve in cases of implant rupture, and cleansing of the breast pocket is achieved by debulking only. Further studies are required to determine whether dimethyl sulfoxide, because of its clinical properties, has an advantage over saline in this setting by reducing the capsular contracture rate. DISCLOSURE No financial support or benefits have been received by any of the authors from any commercial source that is related directly or indirectly to the scientific work reported on in this article. Sagit Meshulam-Derazon, M.D. Department of Plastic Surgery Rabin Medical Center Beilinson Campus Petah Tiqwa, Israel and Sackler Faculty of Medicine Tel Aviv University Tel Aviv, Israel Igal Bar-Ilan, Ph.D. MIGAL-Research Institute Kiryat Shmona, Israel Ron Azaria, M.D. Dean Ad-El, M.D. Department of Plastic Surgery Rabin Medical Center Beilinson Campus Petah Tiqwa, Israel and Sackler Faculty of Medicine Tel Aviv University Tel Aviv, Israel

Final Report of the Amended Safety Assessment of Sodium Laureth Sulfate and Related Salts of Sulfated Ethoxylated Alcohols

Sodium laureth sulfate is a member of a group of salts of sulfated ethoxylated alcohols, the safety of which was evaluated by the Cosmetic Ingredient Review (CIR) Expert Panel for use in cosmetics. Sodium and ammonium laureth sulfate have not evoked adverse responses in any toxicological testing. Sodium laureth sulfate was demonstrated to be a dermal and ocular irritant but not a sensitizer. The Expert Panel recognized that there are data gaps regarding use and concentration of these ingredients. However, the overall information available on the types of products in which these ingredients are used and at what concentrations indicates a pattern of use. The potential to produce irritation exists with these salts of sulfated ethoxylated alcohols, but in practice they are not regularly seen to be irritating because of the formulations in which they are used. These ingredients should be used only when they can be formulated to be nonirritating.

Quantitative analysis of surfactant deposits on human skin by liquid chromatography/electrospray ionisation tandem mass spectrometry

Surfactants are commonly used as cleansing agents and yet there are concerns that they may also have a role in skin irritation. The lack of suitable methods for the quantitative and qualitative analysis of surfactant deposition on skin has hindered the in-depth investigation of such effects. Here, we report the application of reversed-phase liquid chromatography/electrospray ionisation tandem mass spectrometry (LC/ESI-MS/MS) assays for two surfactants commonly used in consumer products, namely sodium lauryl ether sulfate (SLES) and laurylamidopropyl betaine (LAPB), to a baseline study aiming to assess deposition levels on human skin. The linearity of the assays was established at 3-20 ng, with coefficient of variation below 5%. The detection limits were 100 pg for LAPB and 1 ng for SLES; quantitation limits were 500 pg for LAPB and 2.5 ng for SLES. The baseline study was conducted using a panel of 40 healthy volunteers. Skin extract samples were taken in triplicate from forearms, using ethanol. SLES was detected on most volunteers, with 75% of them having SLES deposits in the range of 100-600 ng/cm(2). LAPB was detected on the skin of all volunteers with 85% of them having deposit levels within the concentration range of 1-100 ng/cm(2). These results demonstrate the extent to which commonly used surfactants remain on the skin during the day. The analytical methods reported here can be applied to the investigation of surfactants in relation to general skin condition and to the development and optimisation of new consumer wash products.

Enhanced Wettability Alteration by Surfactants with Multiple Hydrophilic Moieties

AbstractThe main production mechanism during water flooding of naturally fractured oil reservoirs is the spontaneous imbibition of water into matrix blocks and resultant displacement of oil into the fracture system. This is an efficient recovery process when the matrix is strongly water‐wet. However, in mixed‐ to oil‐wet reservoirs, secondary recovery from water flooding is often poor. Oil production can be improved by dissolving low concentrations of surfactants in the injected water. The surfactant alters the wettability of the reservoir rock, enhancing the spontaneous imbibition process. Our previous study revealed that the two main mechanisms responsible for the wettability alteration are ion‐pair formation and adsorption of surfactant molecules through interactions with the adsorbed crude oil components on the rock surface. Based on the superior performance of surfactin, an anionic biosurfactant with two charged groups on the hydrophilic head, it was hypothesized that the wettability alteration process might be further improved through the use of dimeric or gemini surfactants, which have two hydrophilic head groups and two hydrophobic tails. We believe that when ion‐pair formation is the dominant wettability alteration mechanism, wettability alteration in oil‐wet cores can be improved by increasing the charge density on the head group(s) of the surfactant molecule since the ion‐pair formation is driven by electrostatic interactions. At a concentration of 1.0 mmol L−1 a representative anionic gemini surfactant showed oil recoveries of up to 49% original oil‐in‐place (OOIP) from oil‐wet sandstone cores, compared to 6 and 27% for sodium laureth sulfate and surfactin, respectively. These observations are consistent with our hypothesis.

Differential deposition of emollients from tripartite formulation systems

To date, emollients are included in skin care formulations although not much is known about their adsorption/deposition properties and/or the interactions of the constituents within these multi-component systems. The modulation of the adsorption/deposition via the use of specific surfactant and/or emollient systems could therefore help to increase performance and sensorial benefits as well as to reduce adverse effects. In this study, the effects of various tripartite systems consisting of sodium laureth sulphate (SLES), a co-surfactant and an emollient were studied. The two different emollients tested adsorbed with varying amounts although the same surfactant/co-surfactant system was used. Interestingly, the deposition of both SLES and/or the emollient is also substantially influenced by the emollient component itself as well as by the co-surfactant used. Sensory assessments showed that although SLES has a negative effect on the skin feel, adsorbed emollients improve skin softness and smoothness. These results show that optimization of performance is possible when using a co-surfactant best suited for the emollient.

Hair breakage—How to measure and counteract

A system to determine the efficacy of hair treatments in terms of anti-breakage and split end prevention was developed which involves the repeated combing of hair strands. The device allows ten hair strands to be combed simultaneously. First, the influences of chemical hair treatments like bleaching on hair breakage were examined. In a next step, the protective effects of benchmark products from the market were studied. Since nearly all commercial products with anti-breakage claims contain silicones combined with cationic polymers, alternative actives were searched. In a test series with different waxes in shampoo formulations with a variable number of parameters, the particle size was found to be the factor with the strongest influence on the amount of wax deposited on the shampooed hair. Therefore, a targeted development was started, resulting in a combination of several ethers dispersed in sodium laureth sulfate. Excellent conditioning, anti-breakage and split ends protection properties of the compound were found, showing also a dosage dependency. The latter could be explained by analyzing the amounts of waxes applied on treated hair. In these experiments, a dependency on the concentration in the shampoo was found.

Interlaboratory studies with a proposed patch test design to evaluate the irritation potential of surfactants

Development of cosmetic products and household detergents necessitates comparative study designs to assess the skin tolerance of products. In initial tests, the epicutaneous patch test for irritation is widely used. This study was conducted to develop a protocol that would facilitate a comparison of results obtained when tests are conducted by different laboratories. 'In-house' and standardized patch test protocols were used to assess irritation potentials of surfactant-based products in intra- and interlaboratory studies using defined surfactant samples. The various in-house protocols tested did not consistently produce equivalent results. In order to develop a study design that yields comparable results, various factors were identified and adjusted. The standardized study protocol includes occlusive application of 70 microl of the test substance to the back of 30 subjects, defined reading times and schemes, assessments based mainly on erythema, and inclusion of sodium laureth sulfate and sodium dodecyl sulfate as positive controls as well as water as a negative control. Use of the standardized protocol and training of assessors improved the reliability and consistency of results whereby the irritation potentials of the references and test samples were ranked similarly by the laboratories.

Relative assessment of density and stability of foam produced with four synthetic surfactants

Selection of the surfactant has an impact on many of the foam properties as it affects the surface tension and gas–liquid interfacial properties. The objective is to produce stable aqueous foam of required density. These two characteristics are influenced by the type of surfactant, its concentration and foam generation pressure. This study compares the density and stability of foam produced using four synthetic surfactants namely sodium lauryl sulfate, sodium lauryl ether sulfate, sulfanol and cocodiethanolamide through a systematic experiment design based on response surface methodology. The relative performance has also been assessed in terms of their suitability for use in foamed concrete production based on ASTM test method. The effect of surfactant concentration has relatively lesser effect on foam density for sodium lauryl sulfate and sulfanol irrespective of foam generation pressure adopted. The drainage is proportional to the initial foam density for all the surfactant concentration for ionic surfactants at different foam generation pressures. For all the four surfactants under the optimum foam generation pressure, a stable foam with drainage less than 12% in 300 s (by considering economy as a factor) is achieved. From the foam stability test based on ASTM C 796-97, it is observed that all the four surfactants are suitable for use in foamed concrete production when optimized foam production parameters are adopted.

Effect of a non-ionic surfactant on skin-retention of cationic minoxidil microparticles suspended in an anionic surfactant solution

The effect of Brij 78, a nonionic surfactant, on the interactions between cationic minoxidil (MXD) microparticles and sodium lauryl ether sulfate (SLES) in an aqueous phase was investigated. Cationic MXD microparticles were prepared by high pressure homogenization, where distearyldimethylammonium chloride (DSDMAC) was used as a cationic dispersant. The positive surface charge of MXD microparticles was neutralized at the equimolar ratio of SLES/DSDMAC and became negative in the presence of excess amount of SLES, whether Brij 78 was included in the MXD suspensions or not. On the other hand, when nonionic surfactant was included in the suspension so that the molar ratio of Brij 78/DSDMAC was 0.063: 1, the suspension of the cationic microparticles was stable in terms of turbidity change even in the presence of excess amount of SLES. It means that while electrostatic interactions between DSDMAC and SLES were occurring, the aggregation of cationic MXD microparticles was prevented with the aid of Brij 78. Due to the cationic microparticle-stabilizing effect of Brij 78 in the presence of the anionic surfactant, the substantivity of the cationic MXD microparticles having Brij 78 was about two times higher than that of the microparticles without the nonionic surfactant.

Study of adsorption kinetics of surfactants onto polyethersulfone membrane surface using QCM-D

The adsorption kinetics of surfactants onto the crystal surface spin-coated with a thin layer of a model membrane material, polyethersulfone was monitored through measurements of frequency and dissipation shifts simultaneously using a quartz crystal microbalance with dissipation (QCM-D) apparatus. In this study, the viscoelastic behaviors of the adsorbed surfactant layers of sodium laureth sulfate, cocamidopropyl betaine and their mixed solution (1:1) expressed through the dissipation parameters from the QCM-D measurements were used to deduce the structures of the adsorbed layers of the surfactants as a combinative result of characteristics of the surfactant and the hydrophobicity of the membrane surface.