Nonionic Surfactant Systems Research Articles

Removal of nickel ions from aqueous solution by micellar-enhanced ultrafiltration, using mixed anionic–non-ionic surfactants

The aim of this study was to investigate the performance of single and mixed surfactants, both non-ionic and anionic, for the removal of nickel from aqueous solution using micellar-enhanced ultrafiltration (MEUF). To achieve this objective, SDS and four non-ionic surfactants with different ethylene oxide (EO) group length were utilized in this work. Furthermore, the synergistic interaction of non-ionic surfactants with SDS micelles was evaluated using β interaction parameter for TX100. The synergistic behavior of non-ionic surfactants in the SDS micelles was demonstrated, in view of the fact that the interaction parameter had a negative value. In this work, the effects of parameters such as SDS and nickel concentration, pressure and pH on the nickel rejection rate were examined in VCF=1.7 at 25°C. The optimum SDS and nickel concentration were determined 8mM and 10ppm (rejection was about 100%), respectively. It was also concluded that in the non-ionic surfactant and SDS system, the nickel rejection rate was considerably enhanced from 56% to 98%, 99%, 96% and 95%, using TX114, TX100, Brij35 and TX405, respectively for a particular concentration of SDS (i.e., 3.2mM). Furthermore, the molar mass concentration and EO group length of non-ionic surfactants in the MEUF had a considerable effect on the performance; i.e., the surfactants with lower molar mass would lead to a higher flux rate and retention.The findings of this study also revealed that as the SDS concentration was increased, the mean micelle size in the SDS and nickel solutions would also decrease accordingly.

Cosolubilization of 4,4′-dibromodiphenyl ether, naphthalene and pyrene mixtures in various surfactant micelles

Abstract The present study aims to investigate the cosolubilization of a range of mixtures of polybrominated diphenyl ether (PBDE) (specifically, 4,4′-dibromodiphenyl ether) and two polycyclic aromatic hydrocarbons (PAHs) (specifically, naphthalene and pyrene) in nonionic, cationic, and anionic surfactant systems. Cosolubilization effects were quantified in terms of molar solubilization ratio, micelle-water partition coefficient, and synergistic/suppressive ratio. 1 H nuclear magnetic resonance (NMR) spectroscopy was used to investigate the solubilization sites of naphthalene, pyrene, and 4,4′-dibromodiphenyl ether in surfactant micelles. During cosolubilization, synergism was observed for naphthalene/pyrene in Tween80, Brij58, CTAB, and SDBS micellar solutions due to palisade layer solubilization of naphthalene and pyrene that resulted in reduction of interfacial tension, enabling the core volume to increase. In contrast, inhibition occurred in Brij78 surfactant system due to weak interactions between PAHs and the hydrophilic chain, and competitive solubilization of PAHs for the same solubilization site. 4,4′-Dibromodiphenyl ether probably had great affinity for hydrophilic chains of surfactants due to non-covalent halogen bonding that occurred between bromines and electron donors on the hydrophilic chains, resulting in synergism for 4,4′-dibromodiphenyl ether/pyrene in all surfactant systems and resulting in inhibition for 4,4′-dibromodiphenyl ether/naphthalene in Brij58, Brij78, and CTAB surfactant systems. The results of this study provide valuable information that may improve the effective utilization of surfactants in removal of PBDEs and PAHs from contaminated soils and non-aqueous phase liquids (NAPLs) treated with surfactant enhanced remediation (SER) technology.

Multilamellar vesicle formation from a planar lamellar phase under shear flow.

The formation of multilamellar vesicles (MLVs) from the lamellar phase of nonionic surfactant system C12E5/D2O under shear flow is studied by time-resolved small angle neutron and light scattering during shear flow. A novel small angle neutron scattering sample environment enables the tracking of the lamellae alignment in the velocity-velocity gradient (1-2) plane during MLV formation, which was tracked independently using flow small angle light scattering commensurate with rheology. During the lamellar-to-multilamellar vesicle transition, the primary Bragg peak from the lamellar ordering was observed to tilt, and this gradually increased with time, leading to an anisotropic pattern with a primary axis oriented at ∼25° relative to the flow direction. This distorted pattern persists under flow after MLV formation. A critical strain and critical capillary number based on the MLV viscosity are demonstrated for MLV formation, which is shown to be robust for other systems as well. These novel measurements provide fundamentally new information about the flow orientation of lamellae in the plane of flow that cannot be anticipated from the large body of previous literature showing nearly isotropic orientation in the 2,3 and 1,3 planes of flow. These observations are consistent with models for buckling-induced MLV formation but suggest that the instability is three-dimensional, thereby identifying the mechanism of MLV formation in simple shear flow.

Effect of Branched Alcohols on Phase Behavior and Rheology of Nonionic Surfactant Systems

The effect of single- and double-branched alcohols on the phase and rheological behavior of the laurylsulfobetaine (LSB)/water system was studied, with special attention to the reverse micelles region. In our case, reverse micelle phases behaved as Newtonian fluids where alcohols play the role of solvent. Indeed, it can be concluded that the extension of the reverse micelles phase is determined by the alcohol miscibility in water. Regarding liquid crystals, it is observed that the lamellar phase exhibits gel-like behavior and is the most sensitive to the type of alcohol, affecting the elastic properties and the yield stress values. On the contrary, the hexagonal liquid crystal is barely sensitive to the kind of alcohol. In addition, a comparative study of the phase and rheological behavior of two dodecyl surfactants with different head groups (sulfobetaine LSB, and poly(oxyethylene) Brij-35) as a function of surfactant and tert-butyl alcohol concentrations was performed, revealing two completely different...

Optimization of isothermal low-energy nanoemulsion formation: Hydrocarbon oil, non-ionic surfactant, and water systems

Nanoemulsions can be fabricated using either high-energy or low-energy methods, with the latter being advantageous because of ease of implementation, lower equipment and operation costs, and higher energy efficiency. In this study, isothermal low-energy methods were used to spontaneously produce nanoemulsions using a model system consisting of oil (hexadecane), non-ionic surfactant (Brij 30) and water. Rate and order of addition of surfactant, oil and water into the final mixture were investigated to identify optimal conditions for producing small droplets. The emulsion phase inversion (EPI) and spontaneous emulsion (SE) methods were found to be the most successful, which both require the surfactant to be mixed with the oil phase prior to production. Order of addition and surfactant-to-oil ratio (SOR) influenced the particle size distribution, while addition rate and stirring speed had a minimal effect. Emulsion stability was strongly influenced by storage temperature, with droplet size increasing rapidly at higher temperatures, which was attributed to coalescence near the phase inversion temperature. Nanoemulsions with a mean particle diameter of approximately 60nm could be produced using both EPI and SE methods at a final composition of 5% hexadecane and 1.9% Brij 30, and were relatively stable to droplet growth at temperatures <25°C.

Mixed system of ionic liquid and non-ionic surfactants in aqueous media: Surface and thermodynamic properties

The mixed system of ionic liquid (IL) tetraethyl ammonium tetrafluoroborate [TEA(BF4)] and numerous ethylene oxide based non-ionic surfactants in aqueous media were studied using surface tension, viscosity and dynamic light scattering (DLS) measurements. Various surface properties like critical micelle concentration (cmc), maximum surface excess concentration (Γmax), minimum surface area per surfactant molecule (Amin), surface tension at the cmc (γcmc), adsorption efficiency (pC20), and effectiveness of surface tension reduction (πcmc) as well as thermodynamic parameters of micellization have been determined. DLS and viscosity measurements revealed that the micellar growth was attributed to the bridged solvophilicity of the POE chain in surfactants at elevated temperatures. In most of the cases, the progression ensues from exothermic to endothermic with increase in temperature of the mixed system. Thermodynamic parameter indicates that the micelle formation process is enthalpy driven at low temperature and entropy driven at higher temperature.

Self assembly and rheology of emulsions-mimicking food emulsion rheology

An investigation has been carried out to understand the microstructure of amino based surfactant (cocoyl glutamic acid, CGT) and viscoelastic properties of emulsions mimicking the food emulsion rheology. The structural modulation of the surfactant aggregates depends on the degree of neutralization, temperature and oil concentration. Phase behaviour of the CGT surfactant system behaves similar to a short chain (C 12 EO 8 ) ( Aramaki & Khalid, 2004 ) or a long chain (C 12 EO 25 ) ( Rodriguez, Shigeta, & Kunieda, 2000 ) non-ionic surfactant systems, depending on the degree of neutralization. Krafft point of the CGT surfactant has been decreased with the addition of triethanolamine (TEA) and temperature. In presence of oil liquid crystal structure has been modified, which is due to the changing of the surfactant layer curvature ( Kunieda, Umizu, & Aramaki, 2000 ). It is interesting to note that the I 1 phase solubilizes large amount of oil. High viscosity with large amount of oil emulsions were obtained when the degree of neutralization, n = 1.2. The decrease in viscosity with the oil content in the O/I 1 emulsions is ascribed to the lower volume fraction of the continuous phase (I 1 phase).

PEGylated non-ionic surfactant vesicles as drug delivery systems for Gambogenic acid

Gambogenic acid (GNA), a popular Chinese traditional medicine, has its limitations of coming into use due to its low aqueous solubility and poor bioavailability. In this study, therefore, the PEGylated non-ionic surfactant vesicles drug delivery systems were prepared from biocompatible non-ionic surfactant of Span60, cholesterol and dicetyl phosphate (DCP) by the improved ethanol injection method, and were modified with a polyethylene glycol monostearate15 (PEG15-SA). PEG15-SA, as a biocompatible, non-toxic and non-immunogenic hydrophilic segment, was grafted onto the surface of colloidal niosomes carries to reduce the uptake by the reticuloendothelial system (RES), prolonging the circulation time and attaining higher entrapment efficiency. To our knowledge, this work is the first to report that PEG15-SA was applied to coating of niosomes for encapsulation of GNA. The optimized PEG-GNA-NISVs (P-GNA-NISVs) were characterized in terms of mean vesicles size, polydispersity index (PDI), Zeta potential and entrapment efficiency of the P-GNA-NISVs. The results showed that the mean diameter, PDI, Zeta potential, and the entrapment efficiency of the P-GNA-NISVs were 70.1 nm, 0.166, −44.3 mV and 87.74%, respectively. Furthermore, the release studies of GNA from PEGylated niosomes in vitro and the pharmacokinetics in vivo exhibited a prolonged release profile as studied over 24 h. In conclusion, the result suggests that P-GNA-NISVs prepared in this way not only have higher encapsulation capacity, more colloidal stability but also offer an approach that the PEGylated niosomes is a promising carrier for anticancer GNA.

Worm-Like Soft Nanostructures in Nonionic Systems: Principles, Properties and Application as Templates

The principles, occurrence, structure and properties of worm-like micellar solutions in nonionic surfactant systems is reviewed, with focus in certain experimental methods used to characterize such soft nanostructured systems. Formulation plays a critical role in the design of worm-like micellar systems and derived viscoelastic networks. Micellar growth in one dimension, and hence formation of worm-like aggregates, is favoured by an increase in the average surfactant molecular packing parameter. Such an increase can be induced by addition of cosurfactant or amphiphilic oil that tends to penetrate in the surfactant palisade layer and reduce the specific surface area. On the other hand, long and bulky oils prone to be solubilized in the micellar core, cause a rod-sphere transition and therefore a decrease in viscosity. Salts have a small effect on the behaviour of nonionic worm-like micelles, contrary to what is found for ionic surfactant systems. The effect of raising temperature on worm-like micellar solutions is the result of a balance between the dehydration of the surfactant head groups, which favors elongation, the kinetics of micellar disruption and the formation of structures with nearly zero curvature. Therefore, a viscosity maximum as a function of temperature is found in many systems. Reverse worm-like micelles with a hydrophilic core can also be formed in organic solvents, even in the absence of ionic components or water. Worm-like micelles are useful as templates for the formation of ordered mesoporous oxides. The interaction of micelles with silica species results in the formation of silica-surfactant complexes that later precipitate as hexagonal phase via a cooperative mechanism.

Investigation of antioxidant activity of Quercetin (2-(3, 4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-chromen-4-one) in aqueous micellar media

The interaction of the antioxidant Quercetin with the hydroxyl radical (generated by Fenton's reaction) in presence of cationic (DDEAB, DTPB), nonionic (Brij30), anionic (SDBS, SDS) and their mixed binary and ternary surfactant systems (DDEAB-Brij30, DTPB-Brij30, SDBS-Brij30, SDS-Brij30, DDEAB-DTPB-Brij30, SDBS-SDS-Brij30) was followed by spectrophotometric and tensiometric methods to evaluate oxidation kinetics and hydroxyl radical scavenging activity (RSA) of Quercetin. The analysis of the data was done using the first order kinetic model. Coefficient of Determination (R2) was used as a statistical measure for comparison of the experimental values with the model simulated values. The rate of oxidation of Quercetin was found to depend on nature and concentration of the surfactant used. The rate constant of oxidation reaction (k) observed in different micellar systems with varying surfactant concentration exhibits the same trend as that of the RSA. Both k and RSA values of Quercetin were higher within ionic micelles than in nonionic micelles. In mixed binary micelles the values were intermediate between those for single surfactant systems except in DTPB-Brij30 where the values were higher. However, these values exhibited enhancement in mixed ternary cationic–cationic–nonionic surfactant systems when compared with anionic–anionic–nonionic mixed systems. The results are explained on the basis of compartmentalization and orientation of Quercetin in micellar nanostructures.

Energetics of clouding and size effects in non-ionic surfactant mixtures: The influence of alkyl chain length and NaCl addition

The clouding behavior of two non-ionic mixed surfactant systems (n-dodecyl-β-d-maltoside/n-dodecyl-hexaethylene-glycol and n-decyl-β-d-maltoside/n-dodecyl-hexaethylene-glycol) was investigated over the entire composition range in pure water and in 1M NaCl. The evolution of micellar size as a function of temperature was monitored by dynamic light scattering and a unimodal distribution pattern of aggregates consistent with a single scattering species was found. Our results confirm that an increase of temperature induces micellar growth and that clustering of micelles occurs as the temperature approaches the cloud point. It was observed that, with increasing temperature, the higher the n-dodecyl-hexaethylene-glycol content the greater the micellar growth. The presence of sugar surfactant monomers in the mixed micelle enhances the cloud point of the system. This phase behavior is sensitive to the presence of NaCl in the micellar solution which induces cloud point depression. For a certain system composition, the cloud point decreases as the alkyl chain length of the sugar-based surfactant increases. Cloud-point thermodynamics were evaluated assuming that clouding indicates the solubility limit when phase separation occurs. The micelle–solvent interactions were characterized from the compensation temperatures, which were determined from the enthalpy–entropy plots.

Structural Evolution in the Isotropic Channel of a Water–Nonionic Surfactant System That Has a Disconnected Lamellar Phase: A 1H NMR Self-Diffusion Study

We showed in a previous study that a water-nonionic surfactant system, where the surfactant is a 9:1 mixture of tetraethylene glycol monodecyl ether (C(10)E(4)) and pentaethylene glycol monodecyl ether (C(10)E(5)), forms a disconnected lamellar (L(α)) phase. Thus, the isotropic phase spans the whole concentration range from the water-rich L(1) region to the surfactant-rich L(2) region of the phase diagram. The L(1) and L(2) regions are connected via an isotropic channel that separates the two regions of the L(α) phase. In this letter, we monitored the structural evolution of the isotropic phase along a path through this isotropic channel via (1)H NMR self-diffusion measurements. We used this technique because it enables us to distinguish between discrete and bicontinuous structures by comparing the relative self-diffusion coefficients (obstruction factors) D/D(0) of the solvents (i.e. of water and surfactant in the present case). We found that the obstruction factor of water decreases whereas the obstruction factor of the surfactant increases with increasing surfactant concentration and increasing temperature. This trend is interpreted as the transition from a water-continuous L(1) region, which contains discrete micelles, to a bicontinuous structure, which may extend to very high surfactant concentrations. Although there is good evidence of bicontinuity over a broad concentration range, there is no evidence of inverse micelles or any other microstructure at the highest concentration studied in the surfactant-rich L(2) phase.

Single non-ionic surfactant based self-nanoemulsifying drug delivery systems: formulation, characterization, cytotoxicity and permeability enhancement study

Single non-ionic surfactant based self-nanoemulsifying drug delivery system (SNEDDS) was formulated and characterised for poor water soluble drug, Atorvastatin calcium. Capmul MCM oil showing highest solubility for Atorvastatin calcium was selected as oil phase. Self-nanoemulsifying capacity of Cremophor RH 40, Cremophor EL, Tween 20, Tween 60, Tween 80 and Labrasol were tested for the selected oil. In vitro dissolution studies were performed and were characterized by t85% and dissolution efficiency (DE). Cytotoxicity of the formulations and permeation enhancement of the drug across caco-2 cell monolayer was assessed. Capmul MCM was found to be better nanoemulsified in decreasing order of Cremophor RH 40 > Cremophor EL > Tween 20 > Tween 60 > Tween 80. Values of droplet size (range 11–83 nm), polydispersity index (range 0.07–0.65); zeta potential (range −3.97 to −19.0) and cloud point (60–85°C) before and after drug loading proves the uniformity and stability of the formulations. SNEDDS formulated with Tween 20 surfactant showed enhanced dissolution with t85% and DE values at 10 min and 78.70, respectively. None of the formulation showed cytotoxicity at the concentration tested. Tween 20 based SNEDDS enhanced permeation of the drug as compared with pure drug across cell lines. It can be concluded that SNEDDS can be formulated by using single non-ionic surfactant system for enhance dissolution and absorption of poorly soluble drug, Atorvastatin calcium.

Bilayer swelling of nonionic surfactant and sodium dodecylsulfate mixed system by refractive-index matching

Bilayer swelling behavior of nonionic and anionic surfactant mixed aqueous solution induced by adding glycerin was studied. The phenomenon were performed on a system, polyethylene glycol ether of tridecyl alcohol with the average number of ethylene oxide of 5 (CH3(CH2)12(OCH2CH2)5OH; abbreviation IT5) and SDS mixed aqueous solution, with white cream of the upper phase and micelles (L1) of the lower phase. White cream containing densely packed multilamellar vesicles was revealed by freeze-fracture transmission electron microscopy and polarized microscope observations. Phase transition from white cream/L1, two-phase, to clear unique vesicle phase can be induced by adding glycerin to replace water. The addition of glycerin lowers the turbidity of the dispersion and swells the interlamellar distance between bilayers, which could be explained by refractive-index matching between solvent and bilayers.

Wettability of a PTFE surface by cationic–non-ionic surfactant mixtures in the presence of electrolytes

The increase in wettability of a low surface energy solid surface has become an important task for different applications, and this can be improved by the help of surfactant solutions. On the other hand, reduction of surfactant consumption without compromising the wettability may be of great importance from an environmental and economic viewpoint. So in this work, we studied the effect of two different electrolytes as additives in the presence of cationic (cetyltrimethylammonium bromide, CTAB) and nonionic (Igepal CO-630) surfactant mixtures on the wetting of a low energy PTFE (polytetrafluoroethylene) surface. Different physicochemical properties such as critical micelle concentration (CMC), surface excess (Γmax), minimum area per molecule (Amin), and interaction parameters (β) have been estimated for the mixed surfactant and mixed surfactant with electrolyte solutions. The cationic–nonionic mixed surfactant system showed a synergetic behavior and a maximum synergism was observed for the mixed surfactant in the presence of electrolytes. The addition of electrolytes in the mixed surfactant solution increases the wettability by achieving minimum contact angle (74.6°) at the PTFE–water interface and reduces the consumption of surfactants up to 85% compared to the pure CTAB.

Complex Phase Behavior in the Transition Region Between Gel (L β ) and Lamellar (L α ) Phases for a Commercial Nonionic Surfactant System, C12-14EO3

Surfactant formulators are faced with many challenges during product processing and manufacture, with increased problems from the use of commercial surfactants. Commercial surfactants have a distribution of EO sizes which can dramatically affect the product properties. The gel (L β )/lamellar (L α ) phase transition of a commercial surfactant C12-14EO2.9/water system is shown to split into two, with the sequence ↔ L α being observed, where the region occurs over a ca. 10°C temperature range. In addition, both the gel and lamellar phases can incorporate at least 2–3 times more water than the pure surfactants before the formation of a separate aqueous phase. So while commerical surfactants could pose problems for formulators, they could also offer the possibility of enhanced solubilization of actives in the lamellar regions coupled with the enhanced emulsion stabilization by the gel phase.

Emulsion polymerization of styrene: Simulation the effects of mixed ionic and non-ionic surfactant system in the presence of coagulation

A detailed model was developed for emulsion polymerization of styrene in batch reactor to predict the evolution of the product particle size distribution. The effect of binary surfactant systems (ionic/non-ionic surfactants) with different compositions was studied. The zero–one kinetics was employed for the nucleation rate, with the model comprising a set of rigorously developed population balance equations. The modeling incorporated particle formation by both nucleation and coagulation phenomena. The partial differential equations describing the particle population were discretized using finite volume elements. Binary surfactant systems, comprising sodium dodecyl sulfate (SDS) as anionic, and a commercial polyether polyol (Brij35 ®) as non-ionic surfactants, were examined with different mass ratios. Increasing non-ionic surfactant mass fraction in binary surfactant system showed the decrease of particle number due to intensifying the coagulation between particles. Broader particle size distributions with greater average particle size were obtained with non-ionic surfactant comparing those obtained with anionic one.

Tuning High Aqueous Phase Uptake in Nonionic Water-in-Oil Microemulsions for the Synthesis of Mn–Zn Ferrite Nanoparticles: Phase Behavior, Characterization, and Nanoparticle Synthesis

In this work, the formation of water-in-oil (w/o) microemulsions with high aqueous phase uptake in a nonionic surfactant system is investigated as potential media for the synthesis of Mn-Zn ferrite nanoparticles. A comprehensive study based on the phase behavior of systems containing precursor salts, on one hand, and precipitating agent, on the other hand, was carried out to identify key regions on (a) pseudoternary phase diagrams at constant temperature (50 °C), and (b) pseudobinary phase diagrams at constant surfactant (S):oil(O) weight ratio (S:O) as a function of temperature. The internal structure and dynamics of microemulsions were studied systematically by conductivity and self-diffusion coefficient determinations (FT PGSE (1)H NMR). It was found that nonpercolated w/o microemulsions could be obtained by appropriate tuning of composition variables and temperature, with aqueous phase concentrations as high as 36 wt % for precursor salts and 25 wt % for precipitating agent systems. Three compositions with three different dynamic behaviors (nonpercolated and percolated w/o, as well as bicontinuous microemulsions) were selected for the synthesis of Mn-Zn ferrites, resulting in nanoparticles with different characteristics. Spinel structure and superparamagnetic behavior were obtained. This study sets firm basis for a systematic study of Mn-Zn ferrite nanoparticle synthesis via different scenarios of microemulsion dynamics, which will contribute to a better understanding on the relationship of the characteristics of the obtained materials with the properties of the reaction media.

Rheological and rheo-SALS investigation of the multi-lamellar vesicle formation in the C12E3/D2O system

Usually in nonionic surfactant aqueous systems of the CnEm type, a lamellar phase occurs over a wide temperature and concentration range. For some CnEm surfactants, multi-lamellar vesicle (MLV) formation has been observed when the lamellar phase is subjected to shear flow.This communication reports the shear flow behavior at different shear rate values of a CnEm (where “n” is 12 and “m” is 3) aqueous system at 34°C. The typical transient viscosity behavior of the shear-induced MLV formation in C12E3/D2O at 50wt% of surfactant has been observed. The MLV formation is confirmed by time-resolved rheo-small angle light scattering (SALS) experiments. The experimental data show an intermediate structure that has been attributed to a multi-lamellar cylinders (MLCs).

A Novel Nonionic, Multi-Surfactant System and Separation Method for the Synthesis of Active Carbonic Anhydrase Nanoparticles

This paper describes a new synthesis and separation method of nanoparticles (NPs) using a non-toxic, non-ionic surfactant systems. The purification steps did not use ethanol or acetone. Results indicate that the wild type bovine Carbonic Anhydrase (CA) activity was enhanced almost 4 times more than the CA encapsulated NPs fabricated by the traditional method. The NPs have are more hydrophilic and also have a higher zeta potential. The well dispersed CA PAA NPs with of 10-30 nm in diameter were obtained. This work also demonstrates a universal method for immobilizing fragile biomacromolecules in NP carriers for biomedical applications.