Microemulsion Solution Research Articles

Ethylbenzene Removal by Froth Flotation Under Conditions of Middle‐Phase Microemulsion Formation II: Effects of Air Flow Rate, Oil‐to‐Water Ratio, and Equilibration Time

Dihexyl sulfosuccinate (aerosol MA or AMA) was used to prepare microemulsion solutions in a study of the froth flotation process in batch mode to remove emulsified ethylbenzene from water. Oil removal, surfactant removal, and enrichment ratio were used to evaluate the performance of froth flotation. In this study, the effects of air flow rate, oil‐to‐water ratio, and equilibration time were investigated. A very high air flow rate was found to create more turbulence in the froth flotation column, resulting in low oil removal. As the oil‐to‐water ratio decreases, the enrichment ratio increases, whereas the oil removal slightly decreases. The froth flotation column with a feed solution in which the oil and water had been allowed to equilibrate was found to yield much higher ethylbenzene removal than that with a nonequilibrium feed solution. When the feed solution was agitated for 40 minutes to induce a state closer to equilibrium than with no mixing, the ethylbenzene removal was nearly as high as that with the equilibrium feed solution.

Morphologically Templated Growth of Aligned Spinel CoFe2 O4 Nanorods.

Uniaxially aligned CoFe2 O4 nanorods are obtained by coprecipitation of Co2+ , Fe2+ , and C2 O4 2- ions in a microemulsion solution, and subsequent high-temperature decomposition of CoFe2 (C2 O4 )3 . Each nanorod is made up of a "tectonic" assembly of CoFe2 O4 nanocrystals. Magnetization of such CoFe2 O4 materials may lead to their use in high-density magnetic recording media and high-performance electromagnetic and spintronic devices.

The healing effect of TGF-$alpha; on gastric ulcer induced by acetylsalicylic acid in rats

The present study was designed to investigate the effects of microemulsion and aqueous solution containing transforming growth factor alpha (TGF-α) and/or aprotinin administered intragastrically (i.g.) on healing of acute gastric ulcers induced by acetylsalicylic acid (ASA). The microemulsion was prepared by modification of the microemulsion formulation described in our previous study. Acute gastric lesions were induced by the application of ASA (150 mg/kg in 1.5 ml of 0.2 N HCl i.g.). TGF-α in solution or microemulsion formulations were administered at a dose of 10 μg/kg per 24 h i.g. for 2 days. The effects of TGF-α on the healing was evaluated with the measurement of ulcer score, basal gastric acid secretion, total protein content of gastric fluid, gastric mucus level and histological analysis. The results indicated that the highest decrease in ulcer area was observed in group treated with microemulsion containing TGF-α plus aprotinin (TA-ME). TGF-α in microemulsion formulation was more effective than TGF-α in solution formulation in the increase of gastric mucus secretion, in the decrease of gastric acid secretions and ulcer scores. Histological evaluation of the gastric mucosa samples revealed that, best recovery was obtained in the TA-ME treated group.

The healing effect of TGF-α on gastric ulcer induced by acetylsalicylic acid in rats

The present study was designed to investigate the effects of microemulsion and aqueous solution containing transforming growth factor alpha (TGF-α) and/or aprotinin administered intragastrically (i.g.) on healing of acute gastric ulcers induced by acetylsalicylic acid (ASA). The microemulsion was prepared by modification of the microemulsion formulation described in our previous study. Acute gastric lesions were induced by the application of ASA (150 mg/kg in 1.5 ml of 0.2 N HCl i.g.). TGF-α in solution or microemulsion formulations were administered at a dose of 10 μg/kg per 24 h i.g. for 2 days. The effects of TGF-α on the healing was evaluated with the measurement of ulcer score, basal gastric acid secretion, total protein content of gastric fluid, gastric mucus level and histological analysis. The results indicated that the highest decrease in ulcer area was observed in group treated with microemulsion containing TGF-α plus aprotinin (TA-ME). TGF-α in microemulsion formulation was more effective than TGF-α in solution formulation in the increase of gastric mucus secretion, in the decrease of gastric acid secretions and ulcer scores. Histological evaluation of the gastric mucosa samples revealed that, best recovery was obtained in the TA-ME treated group.

Validation and long-term assessment of an approach for the high throughput determination of lipophilicity (log POW) values using multiplexed, absorbance-based capillary electrophoresis

A critical evaluation of the use of 96-capillary multiplexed microemulsion electrokinetic chromatography (MMEEKC) for the indirect determination of octanol–water partition coefficients (logPOW values) for a wide range of structurally different compounds is presented. The various components of the microemulsion solution were evaluated and optimized for use in a multiplexed capillary format. A six-component calibration mixture and 23 different solutes (n=4 each) were analyzed simultaneously, providing a throughput of up to 46 samples/h, which translates to greater than a 20-fold improvement over existing indirect logPOW methods. Agreement to within ±0.5 logP units of literature values was obtained for 51 of the 54 tested neutral and basic (uncharged) solutes. A linear free energy relationship (LFER) analysis performed on the MMEEKC system supports its use as a viable and effective model of the classical shake-flask method for logPOW determinations. Moreover, a standard deviation of 0.1 or less logP units was obtained for 35 of 36 solutes analyzed repeatedly over an 8-month time period, documenting the long-term effectiveness of the analysis format. Critical comparisons between the proposed MMEEKC method and existing separation methods for the indirect determination of logPOW values are also made. Overall, the results indicate that 96-capillary MMEEKC can serve as a high throughput, cost effective and robust approach and as a valid model for logPOW determinations. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93: 916–931, 2004

Determining Partition Constants of Polar Organic Molecules between the Oil/Interfacial and Water/Interfacial Regions in Emulsions: A Combined Electrochemical and Spectrometric Method

We have developed a new approach for estimating distributions of polar additives in opaque, surfactant based, macroemulsions based on the pseudophase model for homogeneous micellar and microemulsion solutions. The distribution of a polar additive, such as an antioxidant, AO, within emulsions is expressed in terms of two partition constants, one between the oil and interfacial regions, P(O)I, and the other between the water and interfacial regions, P(W)I. To estimate values for P(O)I and P(W)I requires fitting two independent data sets with two independent mathematical relations and solving equations simultaneously for the two parameters. The experimental protocols were developed for determining the partition constants of tertbutylhydroquinone, TBHQ, in a stirred emulsion composed of octane, dilute aqueous acid, and hexaethyleneglycol monododecyl ether, C12E6. One data set was obtained by electrochemical determination of the observed rate constant, k(obs), for reaction of TBHQ with an arenediazonium ion probe as a function of C12E6 volume fraction. The second data set was obtained by determining the partition constant, P(O)W, of TBHQ between octane and water in the absence of surfactant by UV-visible spectrometry. TBHQ is almost 30 times more soluble in water than octane: P(O)W = 27.5. The values of the partition constants in the emulsion are P(O)I = 1.84 x 10(4) and P(W)I = 6.73 x 10(2). The partition constants were used to estimate the fraction of TBHQ in each region; for example, 96% of the TBHQ is located in the interfacial region at 0.02 volume fraction of C12E6. Our approach is quite general and should be applicable to any polar organic compound that reacts with the arenediazonium ion probe in emulsions composed of virtually any type of oil and surfactant. Comparisons of the rate constants for reaction of the antioxidant in the interfacial region of the emulsion, which can be obtained from the electrochemical results, may lead to a scale of antioxidant efficiency that is independent of the distribution of the antioxidant in the emulsion.

Bicontinuous Microemulsion Type Cleansing Containing Silicone Oil. I. Comparison of Solubilization Behavior of Cyclic Siloxane with Polar Oil

In this study, a microemulsion (ME) phase containing silicone oil was prepared, and its detergency was investigated. Decamethyl cyclopentasiloxane (DC), a good solvent for silicone soils, was combined with cosmetic grade alkyl type surfactant, polyoxyethylene (8 mol) glyceryl monoisostearate (PGMI), and ethanol aqueous solution to prepare the ME phase. The relationship between the structure of the surfactant aggregate and detergency of cosmetic soils containing silicone resin was investigated. The ethanol concentration dependence on the solubilization of DC (ME region) was similar to that of typical temperature dependence of hydrocarbon in nonionic surfactant aqueous solution. On the other hand, the solubilization behavior of DC differed from that of polar oil cetyl isooctanoate (CIO), which can be attributed to the miscibility with the alkyl type surfactant and the site for the solubilization in the micelle. Detergency of the cosmetic soils in a series of the ME solution indicated clear improvement with increasing aggregation number of the surfactant. From the results, it was shown that preparation of ME with large aggregation number such as bicontinuous phase containing DC could provide a good solution for cleansing silicone soils.

Selective nitration of phenol to ortho-nitrophenol using dilute nitric acid by microemulsion of cetytrimethylammonium bromide (CTAB) in isooctane

The paper reports near-selective nitration of phenol to ortho-nitrophenol using CTAB microemulsion solution in the presence of dilute nitric acid. The difference betweem the selective nitration of different kinds of surfactants such as AOT (anionic surfactant) and CTAB (cationic surfactant) has been investigated. All these experimental results indicate that microemulsions can be selective to give the ortho-phenol.

Comparing micellar electrokinetic chromatography and microemulsion electrokinetic chromatography for the analysis of preservatives in pharmaceutical and cosmetic products

In this study, separation and determination of nine preservatives ranging from hydrophilic to hydrophobic properties, which are commonly used as additives in various pharmaceutical and cosmetic products, by micellar electrokinetic chromatograpy (MEKC) and microemulsion electrokinetic chromatography (MEEKC) were compared. The effect of temperature, buffer pH, and concentration of surfactant on separation were examined. In MEKC, the separation resolution of preservatives improved markedly by changing the sodium dodecyl sulfate concentration. Temperature and pH of running buffers were used mainly to shorten the magnitude of separation time. However, in order to detect all preservatives in a single run in a MEEKC system, a microemulsion of higher pH was needed. The separation resolution was improved dramatically by changing temperature, and a higher concentration of SDS was necessary for maintaining a stable microemulsion solution, therefore the separation of the nine preservatives in MEEKC took longer than in MEKC. An optimum MEKC method for separation of the nine preservatives was obtained within 9.0 min with a running buffer of pH 9.0 containing 20 m M SDS at 25 °C. A separation with baseline resolution was also obtained within 16 min using a microemulsion of pH 9.5 which composed of SDS, 1-butanol, and octane, and a shorter capillary column at 34 °C. Finally, the developed MEKC and MEEKC methods determined successfully preservatives in various cosmetic and pharmaceutical products.

Solution properties and PGSE-NMR self-diffusion study of C18:1E10/oil/water system

The microemulsion systems of polyoxyethylene-10-oleyl ether/oil/water have been studied. The medium chain triglycerides (MCT) and retinyl palmitate mixture (1:1, w/w) was solubilized up to 9% w/w at the surfactant concentration of 25% w/w. The lowest phase inversion temperature (PIT) of the microemulsion solutions was about 57 8C and showed no phase separation for 6 months at room temperature. The critical micelle concentration (CMC) of polyoxyethylene-10-oleyl ether (C18:1E10) was 1.20/10 5 Ma t 278C. The phase behavior and pulsed field gradient NMR data clearly indicate that these microemulsions are discrete oil-in-water (O/W) microemulsions. The self-diffusion coefficient of free retinyl palmitate, MCT and MCT/retinyl palmitate mixture (1:1, w/w) were 1.61/10 10 , 2.60/ 10 10 and 2.59/10 10 m 2 s 1 , respectively. The D of free C18:1E10 was 4.96/10 11 m 2 s 1 . The relative selfdiffusion coefficients of water and oil differed by more than 1 order of magnitude. The hydrodynamic radius (RH )o f this oil swollen micelle was calculated as 14 nm at 1% w/w oil concentration (23% w/w C18:1E10, 0.5% w/w MCT, 0.5% w/w retinyl palmitate, 76% w/w water) and increased to 34 nm at 7% w/w oil concentration (23% w/w C18:1E10, 3.5% w/ w MCT, 3.5% w/w retinyl palmitate, 70% w/w water). # 2002 Elsevier Science B.V. All rights reserved.

Characteristics of magnetic nanoparticles-bound YADH in water/AOT/isooctane microemulsions

The yeast alcohol dehydrogenase (YADH) covalently bound onto Fe 3O 4 magnetic nanoparticles was performed in the NADH-containing water-in-oil microemulsions of water/AOT/isooctane. Both water and NADH were present in the aqueous phase of microemulsion solution and on particle surface. The ratio of the equilibrium water content on particle surface to that in the aqueous phase of microemulsion solution (i.e. aquaphilicty) was about 0.39 and independent of the molar ratio of water to AOT ( ω 0). The thickness of aqueous film on particle surface was estimated to be 3.1–5.7 nm, increasing with increasing the ω 0 value from 10 to 25. At a constant NADH amount, the concentration of NADH in the aqueous phase of microemulsion solution was not significantly affected by the ω 0 value. In addition, the bound YADH showed excellent storage stability and good thermal stability in the microemulsion system. At 25 °C for 700 h and 75 °C for 30 min, its residual activities were 78 and 56%, respectively. The specific activity of bound YADH in the microemulsion system was 40% of that in aqueous solution. The maximum specific activity of bound YADH ( V max), and the Michaelis constants for NADH ( K m A) and 2-butanone ( K m B) were determined to be 0.0306 μmol/min mg, 0.0589 mM, and 0.1476 M, respectively.

A New Way to Prepare Nanostructured Materials: Flame Spraying of Microemulsions

In this report we describe a new method to obtain nanostructured coatings or powders based on the flame decomposition of microcompartmentalized solutions. Metal nanoclusters of well-defined size are obtained by reduction of a metal salt inside the water compartment of water in oil (w/o) microemulsions, formed by water in hexane and stabilized by an appropriate surfactant. Metal nanoclusters can be separated from the mother solution by spraying the microemulsion solution into an air/acetylene flame. In this way, nanostructured coating or powder, almost preserving the original structure of the nanoparticles synthesized in the microemulsion system, can be obtained in quantities sufficient for industrial applications. As an example we report the flame spraying of gold microemulsions to produce gold coating onto silicon wafers. To the best of our knowledge, this study reports a new method allowing the use of a microemulsion synthetic pathway for the production of consistent amount of nanoparticles. This method could be of great utility in many applications involving nanoparticles in the fields of physics, chemistry, biotechnology, and biology.

Synthesis of pH-Degradable Nonionic Surfactants and Their Applications in Microemulsions

An oil-soluble pH-degradable nonionic surfactant with poly(ethylene glycol) monomethyl ether as the hydrophile and a cyclic ketal as the hydrophobe was synthesized for use in microemulsion-based protein extraction. The surfactant solubilized water in isooctane. Dynamic light-scattering measurements showed formation of fairly monodisperse water-in-oil microemulsions of radii 4−6 nm, with very strong intermicellar attractive interactions. The ternary phase diagram for the system surfactant/water/isooctane at 23 °C consists of one-, two-, and three-phase regions as well as gel-like phases. The well-known “fish” pattern occurred for the phase diagram of temperature vs surfactant concentration at a fixed ratio of water-to-oil (1/1 g/g). The surfactant remained stable at neutral pH for several days but degraded rapidly when a mildly acidic phosphate buffer (pH = 5) was encapsulated in the water-in-oil microemulsion solution. Degradation occurred more rapidly when the microemulsion solution was brought in contact with an equal volume of pH 5 buffer solution in the presence of agitation. The encapsulation of protein (lysozyme) and its subsequent release upon contact with pH 5 buffer were observed, with 70% recovery of lysozyme mass in 0.5 h and 90% recovery in 1.0 h. The specific activity of the recovered lysozyme was within 90.4 ± 4.0% of the value for untreated lysozyme.

Trap State Emission from TiO2 Nanoparticles in Microemulsion Solutions

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTTrap State Emission from TiO2 Nanoparticles in Microemulsion SolutionsHirendra Nath Ghosh and Soumyakanti AdhikariView Author Information Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India Cite this: Langmuir 2001, 17, 13, 4129–4130Publication Date (Web):May 25, 2001Publication History Received10 January 2001Revised5 April 2001Published online25 May 2001Published inissue 1 June 2001https://doi.org/10.1021/la010062iCopyright © 2001 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views741Altmetric-Citations42LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (39 KB) Get e-AlertsSUBJECTS:Emulsions,Nanoparticles,Oxides,Recombination,Semiconductors Get e-Alerts

Titanium dioxide nanoparticles produced in water-in-oil emulsion

Titanium dioxide (titania) particles were prepared by a water-in-oil emulsion system, and studied for the photodecomposition property of methylene blue. Microemulsion (ME) consisted of water, cyclohexane or octane, and surfactant, such as polyoxyethylene (10) octylphenyl ether (TX-100), polyoxyethylene lauryl ether, or bis (2-ethylhexyl) sodium sulfosuccinate. Titanium tetraisopropoxide (TTIP) was dropped into the ME solution and then titania particles were formed by the hydrolysis reaction between TTIP in the organic solvent and the water in the core of ME. It was found that ME could be classified to the reversed micelle (RM) region and the swelling reversed micelle (SM) region according to the water content. The water droplets in RM were almost monodispersed, where the water content was small. On the other hand, the water droplets in SM had a size distribution, although most of the water molecules associated with surfactant molecules. The size of the particles prepared in the RM region was smaller than the ME size. In contrast, the size of the particles formed in the SM region was larger than the ME size, and coagulation of the particles was observed within a few hours. The smallest diameter of the particles was 2 nm in the system of cyclohexane with TX-100 surfactant when the molar ratio of water to surfactant was 2. Titania particles prepared in this condition were collected as amorphous powder, and converted to anatase phase at less than 500 K, which is lower than the ordinal phase transition temperature. These anatase phase titania particles only showed a significant photodecomposition of methylene blue by illumination with a Xenon lamp.

SANS study of associative triblocks in microemulsion solutions

Small-angle neutron scattering was used to study the interactions between AOT/water/decane microemulsions and poly(ethylene oxide)-polyisoprene-poly(ethylene oxide) triblocks. The interdroplet spacing seems to be independent of molecular weight and polymer concentration. Scattering experiments on the polyisoprene layer yield a high q exponent of −1.6 ± 0.1, indicating that the layer is swollen by decane.

Synthesis of Nickel Nanoparticles in Water-in-Oil Microemulsions

The synthesis of nickel nanoparticles by the reduction of nickel chloride with hydrazine in the cationic water-in-oil microemulsions of water/CTAB (cetyltrimethylammonium bromide)/n-hexanol at 73 °C has been studied. By the analyses of electron diffraction pattern and X-ray diffraction, the resultant particles were characterized to be the pure nickel crystalline with a face-centered cubic (fcc) structure. The investigation on the composition of microemulsion solution indicated that the average diameter of nickel nanoparticles was affected mainly by the ratio of CTAB to n-hexanol instead of the size of microemulsion droplets. Smaller particles could be obtained at higher ratios of CTAB to n-hexanol. At a constant nickel chloride concentration, the average diameter of nickel nanoparticles decreased with the increase of hydrazine concentration and then approached to a constant value when the concentration ratio of hydrazine to nickel chloride was above 10. At a sufficient high hydrazine concentration, the av...

Application of Partial Least-Squares Calibration to Phosphorimetric Data for Determination of Polycyclic Aromatic Hydrocarbons in Spiked Environmental Samples

A partial least-squares calibration method is proposed, for the first time, for phosphorescence signals. The proposed method is based on the determination of phenanthrene, fluoranthene, and benz[a]anthracene by room temperature phosphorimetry, using microemulsion solutions. The emission and first-derivative emission spectra of the ternary mixtures were tested to perform the calibration matrix. Improved recoveries were found for the prior differentiation step in the analysis of ternary mixtures of these polycyclic aromatic hydrocarbons in road dust samples. The proposed method yielded recoveries ranging from 93.2 to 115.3%, with relative standard deviations of < 6.8%.

Determination of the Second Virial Coefficient of the Interaction between Microemulsion Droplets by Microcalorimetry

The study proposes a novel method of obtaining the information of second virial coefficient of interactions between microemulsion droplets by microcalorimetry. By use of a high sensitivity isothermal titration microcalorimetry to measure the dilution heat of microemulsions solution, information about the second virial coefficient of the interactions between the microemulsion droplets can be derived with the number density of microemulsion solution. The derivation is based on a hard-sphere interaction potential assumption. The variance of the derived second virial coefficients was verified by the percolation behavior of different reverse micelles solutions of dioctyl sulfosuccinate sodium salt in decane with or without solutes.

Properties of the ammonium form of Versatic 10 in a liquid–liquid extraction system

The commercial reagent Versatic 10 (Shell Chemical) based on a mixture of highly branched isomers of C 10 monocarboxylic acids is used to study the ammonium salt form of an acidic liquid cation exchanger for metal extraction. The degree of neutralisation is varied and the neutralisation process is considered by determining the phase equilibria and analyzing the distribution of components between phases as a function of pH. When gradually neutralising Versatic 10 with aqueous ammonia, first an ammonium carboxylate complex is formed in the organic phase with a stoichiometry of NH 4A⋅4HA⋅ qH 2O where q=1.0–2.5. When the amount of ammonia is further increased a phase inversion is observed at about pH 8.4 as the concentration of Versatic 10 in the aqueous phase dramatically increases and the amounts of water and ammonia dramatically decrease in the organic phase. When concentrated ammonia (>about 2 M) in water is used for neutralisation a one-phase microemulsion is observed at the phase inversion pH. The one-phase region where maximal solubilization takes place is at 50% degree of neutralisation. Compared to normal organic phase this microemulsion solution has higher electrical conductivity and viscosity.