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Microemulsion based fuels (MBF) have gained significant attention in recent years due to their potential to enhance combustion efficiency, reduce emissions, and improve overall engine performance. This research paper enlightens the effects of physiochemical properties on the emission characteristics of CI engine. The microemulsions are formulated using surfactants, co‐surfactants, water or alcohols, and fuel components. The effects of density, viscosity, calorific value, cold flow properties, and cetane number along with the stability and the multi‐component characteristics of (MBF) has been taken into consideration to examine its effects on Emission characteristics such as nitrogen oxides (NOx), sulfur oxides (SOx), carbon monoxide (CO), particulate matter (PM), and unburned hydrocarbons (UHC). Microemulsion‐based fuels lower emissions of NOx and PM, recognized to the more complete combustion. The review highlights various studies that have investigated the benefits of microemulsion fuels, including reduced emissions of different pollutants and thus reduce the adverse effect on environment. In conclusion, microemulsion‐based fuels show likely physiochemical properties, as well as favorable emission characteristics, with reduced NOx, SOx, CO, PM, and UHC emissions. This study highlights the potential of microemulsion‐based fuels as environment friendly alternatives, flagging the way for further research. [ABSTRACT FROM AUTHOR]

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Microemulsion systems are of interest to researchers due to their low energy requirements and thermodynamic stability in a wide range of applications, including enhanced oil recovery, gas absorption, drug delivery, and chemical reaction environments. In this research, the viscosity of microemulsions was characterized and then predicted. Tween 20 and Tween 80 were used as surfactants and n‐butanol as co‐surfactant. Different types of prepared Winsor microemulsions were described using the phase diagram and then were evaluated regarding their viscosity, particle size, and electrical conductivity. The mean droplet size and viscosity of the microemulsion were 8–200 nm and 10.4–39.1 cp, respectively. Finally, a new equation is suggested to predict microemulsion viscosity as a function of the ratio of the dispersed phase fraction to the surfactant fraction. [ABSTRACT FROM AUTHOR]

Cultural heritage assets constitute a fundamental socioeconomic resource, but the actual works of art need to be maintained, counteracting degradation processes, to transfer these benefits to future generations. In particular, the removal of soil, aged coatings, and vandalism/overpaints is one of the most needed interventions in art restoration. Traditional cleaning methodologies, based on classical solution and polymer chemistry, only grant limited control of the cleaning interventions, with the risk of affecting the original components of the artifacts, and often involving the use of toxic or non-environmentally friendly compounds. Alternatively, materials science, colloids, and soft matter have provided valuable and safe solutions in the last decades. This review provides a selection of the most recent and advanced methodologies for the wet cleaning of works of art, spanning from nanostructured cleaning fluids (microemulsions, surfactants swollen micelles) to physical and chemical gels. The new methodologies work on different physico-chemical mechanisms, such as processes for detaching/dewetting, to selectively remove the unwanted layers in sustainable and cost-effective interventions. The best performing systems, like microemulsions confined in "twin-chain" polyvinyl alcohol gels, have been assessed in the cleaning of masterpieces such as works by Pablo Picasso, Jackson Pollock and Roy Lichtenstein. Particular attention is dedicated to "green" chemistry systems, using low-toxicity solvents or bio-based/waste materials to build gel networks. Finally, current trends and future perspectives are given, showing that advanced systems for art cleaning link with transversal fields of crucial importance even beyond Cultural heritage conservation, e.g., detergency, tissue engineering, drug-delivery, food industry and cosmetics. [ABSTRACT FROM AUTHOR]

Amphiphiles and surfactants are surface‐active molecules with special properties at interfaces, and they can undergo different modes of self‐association forming colloidal entities in solution. They can also stabilize other colloidal dispersions including nanoparticles, and help the formation and protection of nanodispersions resulting from chemical reactions. In this study, we have discussed the formation, properties, and applications of such nanocolloid‐like species formed in solution by different methods with special stress on various types of surfactants. Nanoparticles show the difference in melting point, electrochemical properties, conductance, etc., from their corresponding bulk material. Classical thermodynamics is used to explain this property. The basics of such processes, their types, morphology, stability, and usefulness have been presented and discussed. The types of assemblies that arise from the self‐associations of the amphiphiles, and surfactants under different conditions (i.e., micelles, reverse micelles, vesicles, liposomes, niosomes, etc.) have been also presented. Examples of their types, morphologies, transformations, and applications in relation to the stability, and functions of nanodispersions or nanocolloids are exemplified with multiple illustrations from earlier as well as recent research. The use of biosurfactants and block copolymers is also discussed. The stabilization of nanoparticles by "capping" has been discussed in some detail. A short account of the hydrothermal and solvothermal processes of synthesis of nanomaterials using amphiphiles as templates has been also presented. The multiple applications of amphiphile‐mediated nanoscience have been briefly presented and discussed. [ABSTRACT FROM AUTHOR]

Resveratrol (RES) is a polyphenol and phytoalexin present in most of the herbal plants and its products. It is frequently prescribed as a preventing therapy for diseases like cancer, cardiovascular, neurodegenerative and many others. However, it is usually reported the problem of poor water solubility, poor bioavailability, and rapid metabolism, limits its further clinical applications. Self-microemulsifying drug delivery systems (SMEDDS) is an efficient technology that can be used to overcome these limitations. We have optimized and prepared Resveratrol SMEDDS formulations for the first time by using different concentrations of various oils, surfactants, and co-surfactant mixtures. These vehicles helped to construct pseudo ternary phase diagrams and yielded good microemulsion region. Optimized and most stable formulation was selected for further characterizations. Then, the final formulation was identified which was further taken out for stability study in different media and through accelerated stability studies. The results of the dissolution study indicated that the rate of dissolution was higher in comparison to the pure resveratrol. The droplet size of the formulation was less than 100 nm with negative charge. It indicates that the adsorption of negatively charged surfactant molecules at the interface of two phases of the microemulsion. Results of the MTT study showed that, more than 75% of the cells were visible in both the cell lines (HEK-293 & HEP-G2). It gives an indication of biosafety of the formulation. We have successfully synthesized highly solubilized and biocompatible formulation of RES. [ABSTRACT FROM AUTHOR]

Summary: This work investigates the effect of surfactant on the microencapsulation of thermochromic materials (TCMs) by TiO2. Three types of surfactants, namely Cetrimonium Bromide(CTAB), Sodium Dodecyl Benzene Sulphonate (SDBS), and Hexadecanol (HEXA) are deployed during the microemulsion process for the formation of a TiO2 shell layer on a commercial dyeTCM(CDTCM). These off‐the‐shelf CDTCMs are primarily Leuco dye particles that exhibit a color change (black to white) behavior at around 33°C. The role of TiO2 shell material encapsulation is to protect the CDTCMs from solar‐irradiated photodegradation by absorbing harmful UV radiation. Various analytical characterization methods, such as XRD, FTIR, UV‐Vis, DSC, SEM, HRTEM, and EDS were used to evaluate both the plain CDTCM and its TiO2 microencapsulated counterparts in terms of unraveling the structural, microstructural, chemical, and thermal properties. The reversible color change chromic characteristics were quantitatively and qualitatively examined via CIE Lab measurements. The microencapsulated TiO2@CDTCM fabricated in this study shows reversible thermochromic color change behavior and therefore has the potential for applications in energy‐savings in building envelops, smart windows, thermal energy storage and textile industries. [ABSTRACT FROM AUTHOR]

The Hydrophilic-Lipophilic Difference (HLD) model can be described by additive contributions accounting for the effect of the oil and surfactant nature, temperature, ionic strength, and so on. The first step to build an HLD framework for a surfactant class is to have Winsor III phase equilibria in a restricted range of formulation variables. In this respect, anionic and nonionic surfactants are well suited for an HLD study. On the contrary, it is difficult achieve for pure cationic surfactant Winsor III phase equilibria without the addition of alcohols and this has precluded the extension of the HLD to cationic surfactants.In the present contribution, we first propose a system based on a blend of single-tailed and double-tailed cationic surfactant to study the oil contribution, and then we afforded the determination of the surfactant contribution trough an experimental approach (the “HLD-titration”) that is especially tailored for systems displaying a wide range of existence of Winsor III phase equilibria.HLD-titration results confirmed the ionic strength contribution to HLD as a logarithmic function of salinity for cationic-based microemulsions similarly to anionic ones. However, the oil carbon number contribution is almost four-fold larger (k ​= ​0.7 ​± ​0.1) with respect to anionic surfactants. A clearing point was observed in correspondence of the Winsor III phase equilibria under stirring. This approach allows us the determination of the so-called characteristic curvature (Cc), i.e. the term describing the surfactant nature contribution to the film curvature, of the cationic surfactant. Finally, the method was adopted to determine Cc values of 7 quaternary ammonium surfactants differing in the polar heads nature and further three amine oxide surfactant at pH ​= ​1 where they are protonated.

Microemulsions, comprising oil, water and a surfactant, in association with some co-surfactant, are thermodynamically stable systems. They have found applications in a large number of chemical and pharmacological processes due to their unique properties such as large interfacial area, low interfacial tension, and most importantly, the ability to solubilize and deliver hydrophobic drugs. In addition to the oral and intravenous route, they are suitable for drug delivery through the ophthalmic, vaginal, pulmonary, dental, and topical routes. This review highlights the properties and several recent developments in the use of microemulsions for medical treatment purposes including targeted drug delivery.

A possibility of using an oil-in-water microemulsion of the composition 3% of sodium dodecyl sulfate, 8% of n-butanol, 1% of ethyl acetate, and 88% of water (by weight) as an extractant for the extraction and preconcentration of steroid hormones cortisol, cortisone, corticosterone, 11-deoxycortisol, and 11‑deoxycorticosterone from aqueous solutions and urine samples followed by their reversed-phase HPLC analysis with spectrophotometric detection is shown. In optimizing the extraction conditions, the nature of the oil, the time and temperature of extraction, and the time of the separation of the microemulsion were varied. Magnesium chloride was used to destroy the microemulsion. The concentration factors for steroid hormones increase with an increase in the hydrophobicity of the analytes. The limits of detection for steroids were 0.5–3 ng/mL, and concentration factors were 8–20. [ABSTRACT FROM AUTHOR]

This is an introductory review on the diffusion Nuclear Magnetic Resonance (dNMR) as a powerful tool to characterise different types of formulations. Such a technique is nowadays available on most of the NMR instrumentation and enables the determination of the distribution of components and the microstructure of the system. We start with a description, addressed to the formulators, of the methodological strategies to be used to determine the microstructure of different systems. The approaches to be used to quantify the partition/binding equilibria are then sketched. Then, we review recent dNMR applications to formulations containing ionic liquids, surfactants, polymers, and gels. Image 1 • dNMR allows the determination of the the microstructure of a formulations. • dNMR allows the determination of the components distribution in complicated systems. • From diffusivity a volume-averaged size of the components is evaluated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Development of 206 different O/W microemulsions containing babassu oil. • Reducing the HLB value of the surfactant diminishes the amount of babassu oil in O/W ME. • Development of predictive models of the formation region of O/W microemulsions. Microemulsions have gained prominence in the research for biomolecules nanocarriers due to their thermodynamic stability and auto-organization. However, the formation of these systems requires a high experimental effort. To minimise it, an Artificial Neural Network to predict the concentration range of microemulsion formation was developed using weight fraction, hydrophilic-lipophilic balance as model input. We also evaluated the effect of including surfactant viscosity as input. Experimental data were generated using formulations with babassu oil, water, Tween® 80, and Labrasol®. After training, the proposed model presented accuracies up to 93%, with the addition of viscosity reducing the cross-validation variance. [ABSTRACT FROM AUTHOR]

The main goal of the present study was to prepare and evaluate a stable transparent microemulsion with good corneal penetration and reduced frequency of dosing for ocular drug delivery. Extensive pre-corneal loss caused by rapid drainage and high tear liquid are the major drawbacks associated with conventional dosage forms 70% of total dosage forms available in market are conventional forms in which only 1 to 5% of the total drug penetrates into cornea and reaches to the intraocular tissue, To overcome these problems, microemulsion based systems are developed. Microemulsion was prepared by using oleic acid as an oil phase, tween 80 as surfactant, ethanol as co-surfactant and water as aqueous phase. The appropriate amount of drug was introduced into the oil phase with stirring. Mixture of surfactant and co-surfactant was added into the oil phase with vigorous stirring followed by addition of aqueous phase at a constant rate to form a transparent and stable microemulsion. The prepared microemulsions were evaluated for pH, viscosity, drug content, particle size and zeta potential. The optimised microemulsion formulation was appeared to be transparent and have minimum globule size of 12.1nm with 100% intensity, value of zeta potential was-11.11mV, pH 7.4, viscosity 153.23cp with highest in-vitro drug permeation (85%). The ex-vivo study report of optimised formulation using goat cornea also confirmed its permeation effectiveness. [ABSTRACT FROM AUTHOR]

Numerous Alkali/Surfactant/Polymer flooding (ASP) projects have been developed worldwide. Nevertheless, some disadvantages have limited the success of ASP during the execution in field, such as injection lines scaling and strong emulsification of the produced fluids. Commonly, appropriate formulations for particular reservoir conditions are selected after a series of evaluation steps. These includes tests of surfactants, polymers and commercially available alkali, based on the reservoir temperature, reservoir salinity, reservoir water pH, rock permeability, formation type and adsorption of the surfactant on the matrix rock, to obtain the highest oil recovery at the lowest cost. As part of the different strategies adopted for increasing the oil recovery factor, San Francisco oil field, Huila Colombia, was selected in 2012 for ASP flooding application at pilot scale. After two years of injection, ASP effluents affected considerably the quality of water and its treatment for reinjection. The present work focuses on the compositional study of the production effluents obtained after ASP flooding. A detailed analysis using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) allowed disclosing the role of natural organic acids on reducing the interfacial tension which in turn entailed highly stable microemulsions. Together with the added surfactant, naphthenic acids (because of the alkaline pH) prompts the formation of these thermodynamically stable oil in water systems. A test using an acid free oil proved that the formation of microemulsions strongly depends on naphthenic acids presence. Additional tests using oils with different acidity showed the dependence on the naphthenics acids structure over the emulsion stability. The results obtained in this study stands out FT-ICR MS as a prominent tool on understanding breaking and/or clarifying treatment processes from a molecular level point of view and thus, could help on proposing a correct and cost effective water treatment. Image 1 • Outstanding ultra-high resolution mass spectrometry analysis of crude oil as a prominent toolamong the design of better and accurate enhanced oil recovery (EOR) formulations. • Use of (-) ESI FT-ICR MS to obtain compositional information from realalkali-surfactant-polymer (ASP) effluents. •Structural and phase behavior information were correlated to understand the organic acids characteristics and their role in emulsion stability. [ABSTRACT FROM AUTHOR]

Highlights • Waste cooking oil – an excellent additive to diesel fuel in microemulsion form. • Low HLB surfactants and ethanol as intermediates to form fuel microemulsion. • Surfactants and cooking oil enhance the oxidative stability of microemulsion fuel. Abstract Waste cooking oil (WCO) can be used as an energy source to reduce fossil fuel consumption; however, WCO has high viscosity which restricts direct use in diesel engines. Emulsification techniques can be employed for fuel preparation by selecting suitable surfactants and WCO, diesel and butanol or ethanol ratios using a pseudo-ternary phase diagram. Results indicated that a WCO-diesel fuel blend (WDF) with butanol required no surfactants for homogeneous phase blending compared to WDF with ethanol. Phase behavior of WDF-ethanol blends with hydrophobic surfactants was more suitable than WDF-ethanol blends with more hydrophilic surfactants. Kinematic viscosity of WDF blends depended on the amount of surfactant and its hydrophile-lipophile balance (HLB) value. WCO content was determined as a significant factor contributing to WDF viscosity (p < 0.05). Biofuel blends containing 70% v/v diesel fuel, 15–20% v/v WCO, and 15–20% v/v ethanol with Dehydol LS1 or Span 80 at ethanol:surfactant ratio of 9:1 were selected for further analysis of relevant fuel properties. All selected WDFs gave emulsion droplet size at 200 nm or less. Other properties such as water content, carbon residue and copper strip corrosion met values specified by diesel and biodiesel fuel standards. Acid value of WDFs exceeded the standard due to high acid content of WCO. WDFs with ethanol/surfactants showed higher oxidative stabilities than WDFs with butanol. In terms of safety, conditions for storage and transport should be applied for WDFs because of their low flash point. WDFs obtained by this technique may be used in unmodified diesel engines but engine performance should be monitored. [ABSTRACT FROM AUTHOR]

The first scientific paper on microemulsion was published in 1943 by Schulman and Hoar of Cambridge University. Microemulsion is basically made up of oil, water, surfactant and a short-chain alcohol, acid or amide (called 'cosurfactant'). They were called swollen micelles or by some other names but not microemulsion in 1943 or after. It was rechristened 'microemulsion' in 1959 by Schulman et al. who were then at New York's Columbia University. Research in microemulsion became popular in 1980s when there loomed a large spectre of oil scarcity and its eventual effect on human civilization as we are aware today. Microemulsion was thought to be important for tertiary oil recovery. It has also been found to be useful for nanoparticle synthesis, in pesticide formulation, in drug delivery, and in many other ways, and the research on it still has a great potential and importance. In the 75 year of its innovation (and documentation in the literature), a short but succinct article with its flavour and importance is presented here. [ABSTRACT FROM AUTHOR]

Abstract Characterizing protein aggregates in the presence of silicone oil is a long standing challenge for the pharmaceutical industry. Silicone oil is often used as a lubricant in devices that deliver and store therapeutic protein products and has been linked to protein aggregation, which can compromise a drug's effectiveness or cause autoimmune responses in patients. Most traditional technologies cannot quantitatively distinguish protein aggregates and silicone oil in their native formulations for sizes less than 5 μm. We use holographic video microscopy to study protein aggregation to demonstrate its capability to quantitatively distinguish protein aggregates and silicone oil in the presence of varying amounts of the surfactants SDS and polysorbate 80 in the size range of 0.5-10 μm without the need for dilution or special sample preparation. We show that SDS denatures proteins and stabilizes silicone oil. We also show that polysorbate 80 may limit protein aggregate formation if it is added to an IgG solution before introducing silicone oil. [ABSTRACT FROM AUTHOR]

This work examines the simultaneous removal of barium, chromium, manganese, and iron from produced water using microemulsion systems (Winsor II) in a one-step process. The Scheffé net experimental design was used to assess the effect of microemulsion composition in the removal efficiency. The optimum extraction point for the simultaneous removal of metals was composed by (w/w): 72 % aqueous phase (synthetic produced water), 9 % oil phase (n-hexane), and 19% cosurfactant/surfactant (butan-1-ol/saponified coconut oil = 4); reaching values above 94% for all studied metals, demonstrating the viability of the developed methodology for the correct management of metals from produced water. [ABSTRACT FROM AUTHOR]

The large surface area requires using high concentration of surfactants to produce emulsions with small droplets, which poses challenges for industries with respect to safety issues and the potential to introduce unpleasant flavors. In this work, we investigated the factors of interfacial engineering to improve oil loading capacity and reduce surfactant concentration in emulsions while still keeping high optical clarity. The interface was systematically modulated using a fixed concentration (0.05 w/w %) of sorbitan-based surfactants with different hydrophobicity, chain length, and linearity. Particle size and turbidity were evaluated using dynamic light scattering and spectrophotometry. Hydrophilic surfactants were found to produce small droplets when the oil fraction was limited but were less effective for creating a higher oil fraction load. However, blending in hydrophobic surfactants produced smaller uniform droplets, lower turbidities and higher loading capacity owing to the change in the optimum curvature. The results revealed that surfactant-to-oil ratios (SORs) played an important role in emulsion formation at different hydrophobic-lipophobic balance (HLB). In addition, with identical HLB values, surfactants with shorter chains exhibited higher loading capacity than those with longer chains. Further, surfactants with similar backbone linearity were observed to favor emulsifying oils that have similar degrees of saturation. We found that emulsification is influenced by factors beyond hydrophobicity, such as surfactant chain length and linearity, which have been usually overlooked. From the view of interfacial curvature, we report evidence that interfacial engineering can be used to achieve more efficient emulsification, which helps to reduce surfactant content from beverages. This study provides a framework for tailored emulsion systems that bridges the current gaps in knowledge regarding factors hidden behind HLB, including SORs and chain structures. This work has potential application in the food, cosmetic, and pharmaceutical industries. [Display omitted] • Higher loading efficiency achieved by blending surfactants. • Blending surfactants alters optimum curvature of micelle for uniform droplets. • Menthol acts as a co-surfactant in the oil phase improving emulsion clarity. • Short surfactant tails made smaller droplets despite same hydrophilic/lipophilic balance. • Surfactants with linear chains showed higher compatibility with saturated oil. [ABSTRACT FROM AUTHOR]

Nanoemulsions and microemulsions are environments where oil and water can be solubilized in one another to provide a unique platform for many different biological and industrial applications. Nanoemulsions, unlike microemulsions, have seen little work done to characterize molecular interactions at their surfaces. This study provides a detailed investigation of the near-surface molecular structure of regular (oil in water) and reverse (water in oil) nanoemulsions stabilized with the surfactant dioctyl sodium sulfosuccinate (AOT). Vibrational sum-frequency scattering spectroscopy (VSFSS) is used to measure the vibrational spectroscopy of these AOT stabilized regular and reverse nanoemulsions. Complementary studies of AOT adsorbed at the planar oil-water interface are conducted with vibrational sum-frequency spectroscopy (VSFS). Jointly, these give comparative insights into the orientation of interfacial water and the molecular characterization of the hydrophobic and hydrophilic regions of AOT at the different oil-water interfaces. Whereas the polar region of AOT and surrounding interfacial water molecules display nearly identical behavior at both the planar and droplet interface, there is a clear difference in hydrophobic chain ordering even when possible surface concentration differences are taken into account. This chain ordering is found to be invariant as the nanodroplets grow by Ostwald ripening and also with substitution of different counterions (Na:AOT, K:AOT and Mg:AOT) that consequently also result in different sized nanoparticles. The results paint a compelling picture of surfactant assembly at these relatively large nanoemulsion surfaces and allow for an important comparison of AOT at smaller micellar (curved) and planar oil-water interfaces. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microemulsion phase behavior of 'active' live crude oil was measured at 55 °C and 1700 psi by salinity scans using sodium carbonate alkali as a salt and reported. • For the active crude oil investigated, equivalent alkane carbon number (EACN) is an intrinsic property of crude oil and not dependent on oil-to-water ratio or soap-to-surfactant ratio. • EACN of methane was determined to be 10.2, which is in an excellent agreement with values for inactive live oils. Microemulsion phase behavior of live crude oil has been investigated at 1700 psi and 55 °C using an active crude oil with a total acid number of 1.18 mg-KOH/g-oil. The live crude oil was reconstituted by adding 36.0 mol% methane to dead crude oil. Sodium carbonate was used for a salinity scan, and also as an alkali to convert the acid components in crude oil to natural soap. The equivalent alkane carbon number (EACN) of dead crude oil was determined by measuring optimum salinity of dead crude oil and several surrogate crude oils diluted with pure n -alkanes. The optimum salinity of live crude oil was compared to those of dead and surrogate crude oils to determine the EACN of the live crude oil. To keep the surfactant pseudo-phase composition constant in the ternary phase diagram, the molar ratio of crude oil to synthetic surfactant was controlled. The natural soap and synthetic surfactant were kept the same for each volume ratio of crude oil to surfactant solution. The EACN of the crude oil was found to be independent of the soap-to-surfactant molar ratio, which means EACN is an intrinsic property of oil under the experimental conditions investigated. Based on the optimum salinity shift from dead crude oil to live crude oil, the compositional effect of methane with active crude oil was measured to be about the same as for inactive crude oil. The apparent EACN of methane was found to be equal to about 10.2. The solubilization ratio of the live oil at optimum salinity was greater than the value for the dead crude oil. The results indicate that the microemulsion phase behavior of live crude oil with acidic components can be interpreted using classical EACN concepts by the same criteria as that of inactive crude oil. Thus, the effect of the soap generation reaction can be decoupled from the physical interactions. [ABSTRACT FROM AUTHOR]

The introduction of ionic and non-ionic surfactants in different phases of the system significantly influences the colloidal-chemical characteristics of surfactants, the properties of the initial emulsion, the kinetics of styrene polymerization, the size of latex particles and their size distribution.

In the present study, an efficient biosurfactant producing bacterial strain Pseudomonas aeruginosa MKVIT3 was isolated from an oil logging area in Vellore district of Tamil Nadu, India. Liquid chromatography–mass spectrometry (LC‐MS/MS) analysis was performed for the identification of different congeners present in the extracted biosurfactant. The column purified biosurfactant was used to stabilise the formation of silver nanoparticles (NP) using borohydrate reduction in reverse micelles. The silver NP were characterised using UV‐vis absorption spectroscopy, Powder‐XRD TEM analysis and zeta potential. A comparative study of the antimicrobial activity and cytotoxic efficacy was done for the extracted purified biosurfactant and the silver NP. The LC‐MS/MS analysis of the biosurfactant revealed the presence of five rhamnolipid congeners. The synthesised silver NP showed the characteristic absorption peak in UV‐vis at 440 nm. Powder‐XRD and TEM analysis revealed the average particle size of the NP as 17.89 ± 8.74 nm as well as their cubic structure. Zeta potential value of −30.9 mV suggested that the silver NPs are stable in the suspension. Comparative study of the antimicrobial activity revealed that the silver NP are more potent than the biosurfactant in inhibiting the growth of microbes. Cytotoxic activity revealed that the biosurfactant are more effective than the synthesised silver NP. [ABSTRACT FROM AUTHOR]

Gelation in water-based systems can be achieved in many different ways. This review focusses on ways that are based on self-assembly, i.e., a bottom-up approach. Self-assembly naturally requires amphiphilic molecules and accordingly the systems described here are based on surfactants and to some extent also on amphiphilic copolymers. In this review we are interested in cases of low and moderate concentrations of amphiphilic material employed to form hydrogels. Self-assembly allows for various approaches to achieve gelation. One of them is via increasing the effective volume fraction by encapsulating solvent, as in vesicles. Vesicles can be constructed in various morphologies and the different cases are discussed here. However, also the formation of very elongated worm-like micelles can lead to gelation, provided the structural relaxation times of these systems is long enough. Alternatively, one may employ amphiphilic copolymers of hydrophobically modified water soluble polymers that allow for network formation in solution by self-assembly due to having several hydrophobic modifications per polymer. Finally, one may combine such polymers with surfactant self-assemblies and thereby produce interconnected hybrid network systems with corresponding gel-like properties. As seen here there is a number of conceptually different approaches to achieve gelation by self-assembly and they may even become combined for further variation of the properties. These different approaches are described in this review to yield a comprehensive overview regarding the options for achieving gel formation by self-assembly.

Controlling viscosity of aqueous surfactant solutions is very important for practical formulations. This can be done by having polymers interact with surfactants, thereby forming interconnected physical networks, where main ways of interaction are electrostatic and hydrophobic forces. Polymer–surfactant interactions are long established for viscosity control, but there are many ongoing activities. They are driven by wanting more biocompatible systems, which depend intricately on the choice of surfactant and polymer, and general predictions are not simple for such systems. Surfactants form spherical or wormlike micelles or vesicles. By choice of (co)polymers one can construct systems responsive to external parameters, like temperature or pH, for having tailored rheological properties. Here we describe recent developments with a focus on systems of low concentration, being interesting for applications. In summary, rheological control of polymer–surfactant systems is a versatile topic and a field of colloid science with high relevance for practical formulations. [Display omitted] [ABSTRACT FROM AUTHOR]

Microemulsion systems are smart solvent systems which can be applied in homogeneous catalysis. We investigate these multiphase systems to exploit their characteristics for catalytic gas/liquid reactions and processes in aqueous media. One critical aspect from an economic perspective is the quantitative recycling of the catalyst complex dissolved in the multiphase system. Therefore, it is important to know the distribution of the catalyst complex in each of the single phases. In this contribution we analyse the different parameters/factors that may have an influence on the distribution of catalyst complexes in microemulsion systems, e.g. temperature, type of ligand, structure of surfactant, and chain length of surfactant. Afterwards, the derived information is used for the design of a real, industry-oriented application: hydroformylation of long chained alkenes. Hereby, special attention is given to the separation step of a process, which is performed after a homogeneously catalyzed reaction step in a microemulsion system. Process and economic constraints are briefly outlined and compared with operation data, aiming for the reuse of the catalyst in the reaction step and reduced leaching into product streams, even in the case of operational disturbances and shifts in the catalyst distribution. [ABSTRACT FROM AUTHOR]

We propose a short review paper on the mainly adopted techniques for the production of metal nanoparticles in industrial and laboratory scale. The methods are grouped according to the wellknown classification in bottom-up and top-down schemes, with a particular emphasis on the operating conditions specifically adopted. Namely, some aspects concerning the experimental setup, the choice of precursors and reactants and the relevant technical advantages/limitations of the methods are discussed and compared in light of the most recent issues in matter of metal nanoparticles synthesis. [ABSTRACT FROM AUTHOR]

The direct visualization of micelle transitions is a long-standing challenge owing to the intractable aggregationcaused quenching of light emission in the micelle solution. Herein, we report the synthesis of a surfactant with a tetraphenylethene (TPE) core and aggregation-induced emission (AIE) characteristics. The transition processes of surfactant micelles and the microemulsion droplets (MEDs) formed by the surfactant with a TPE core were clearly visualized by a high-contrast fluorescence imaging method. The fluorescence intensity of the MEDs decreased as the size of MEDs increased as a result of weakening of the restriction of intramolecular rotation (RIR). The results of this study deepen our understanding of micelle-transition processes and provide solid evidence in favor of the hypothesis that the AIE phenomenon has its origin in the RIR of fluorophores in the aggregate state. [ABSTRACT FROM AUTHOR]

The aim of this work was the development and characterization of a biocompatible microemulsion ( ME) containing soybean oil ( O), phosphatidylcholine/sodium oleate/ Eumulgin® HRE40 as the surfactant mixture ( S) and water or buffer solution as the aqueous phase ( W), for oral delivery of the poorly water-soluble drugs sulfamerazine ( SMR) and indomethacin ( INM). A wide range of combinations to obtain clear oil-in-water (o/w) ME was observed from pseudo-ternary phase diagrams, which was greater after the incorporation of both drugs, suggesting that they acted as stabilizers. Drug partition studies indicated a lower affinity of the drugs for the oil domain when they were ionized and with increased temperature, explained by the fact that both drugs were introduced inside the oil domain, determined by nuclear magnetic resonance. High concentrations of SMR and INM were able to be incorporated (22.0 and 62.3 mg/mL, respectively). The ME obtained presented an average droplet size of 100 nm and a negative surface charge. A significant increase in the release of SMR was observed with the ME with the highest percentage of O, because of the solubilizing properties of the ME. Also, a small retention effect was observed for INM, which may be explained by the differences in the partitioning properties of the drugs. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:3535-3543, 2015 [ABSTRACT FROM AUTHOR]

The oil removal efficiency for the ex situ extraction of bitumen from oil sands, or ex situ washing of oil-contaminated sand and related processes is determined by the balance of forces at the oil/water and solid/fluid interfaces. The objective of this work is to estimate the balance of forces at the interface using dimensionless numbers, and their use in evaluating and engineering ex situ soil washing processes. To this end, bitumen was removed from bitumen-coated sand particles using a two-step process. In the first step, the particles were mixed with a suitable solvent (toluene) used, primarily, to reduce the viscosity of bitumen. The particles were then mixed with water or an aqueous surfactant solution capable of producing low interfacial tensions with the solvent-bitumen mixture. The fraction of oil retained after washing was evaluated as a function of interfacial tension, solvent/bitumen ratio, mixing time, mixing velocity, and particle size. These ex situ washing conditions were normalized using dimensionless film and particle-based Weber and Capillary numbers. The fraction of oil retained by the particles was plotted against these dimensionless numbers to generate capillary curves similar to those used in enhanced oil recovery. These curves reveal the existence of a critical film-based Weber number and a particle-based Capillary number that can be used in the design or evaluation of soil washing processes. The film-based Weber number also explained literature data that associates interfacial tension with the removal of oil from oil-based drill cuttings, as well as field observations on the role that particle size plays on the removal of oil in soil washing operations. [ABSTRACT FROM AUTHOR]

The partition of non-ionic surfactants between oil and water is an important parameter that influences the performance of surfactant-based separations, the fate of surfactants in the environment, and the absorption by surfactants in living organisms. From a thermodynamics point of view, the partition of surfactants between oil and water can be used as a method to quantify the hydrophilic–lipophilic nature of surfactants and oil. In this work, a group contribution model, the universal functional activity coefficient (UNIFAC) framework, has been modified to fit and predict the partition of alkylphenol, and alkyl ethoxylated surfactants between aqueous and oil phases. To perform such calculations the interaction parameters of an ethoxylate functional group were optimized, including the temperature dependence for functional groups known to form hydrogen bonds (CH 2 CH 2 O H 2 O, OH H 2 O). The optimization was performed by fitting this modified UNIFAC model to experimental partition coefficient of octylphenol ethoxylated surfactants in the excess phases (water and n -heptane) of middle phase microemulsions at 25 and 55 °C and to experimental critical micelle concentration (CMC) data. The modified UNIFAC is capable of predicting the partition of alkylphenol ethoxylates and alkyl ethoxylates with varying degrees of ethoxylation, tail length and temperature and different oils. The predicted partition values correlate with experimental bioconcentration factors (BCFs) reported for alkyl ethoxylates. The model also predicts properly the critical micelle concentration (CMC) of alkyl and alkylphenol ethoxylate surfactants. The predicted partitions also helped estimate the equivalent alkane carbon numbers (EACNs) of various oils. [ABSTRACT FROM AUTHOR]