• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.454-460
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• 2000

It is difficult to accurately evaluate the effect of lipophilic compounds in aqueous reaction system of enzymes because they are immiscible with water. To screen lipophilic inhibitors of tyrosinase which catalyzes the synthesis of melanin in vivo, an optically clear organic system composed of organic solvent, surfactant, and water, often called reverse micelles(RM), was introduced. Optimal RM to let tyrosinase act normally was composed of isooctane as an organic solvent and dioctyl sulfosuccinate(AOT) of 100 mM as a surfactant. When a molar ratio of water to surfactant was 15, tyrosinase(105.3 units) in RM showed a similar reactivity toward 3,4-dihydroxyphenylalanine(0.18 mM) as in the aqueous assay system. In the presence of cinnamic acid, the product formation of tyrosinase reaction was proportional to the reaction time. This indicates that the inhibitory effect of lipophilic compounds could be analyzed in RM.

• Applied Chemistry for Engineering
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• v.28 no.3
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• pp.351-354
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• 2017

An experimental design method was used to optimize the synthesis of gamma-alumina with a superior thermal stability using the reverse micelle method. First, twelve experimental conditions were derived by using the mixture design method to optimize conditions for the ratio of surfactant, water and oil, which are main factors in the synthesis process. When the particles synthesized by reverse micelle method were calcined at $900^{\circ}C$ under the designed condition, they all had gamma-alumina crystal structure although there were differences in particle sizes. The coefficient of determination of the second-order regression model using the derived experimental results was 93.68% and the P-value was 0.002. The synthesis conditions forgamma-alumina with various particle sizes were presented using surface and contour lines. As a result, it was calculated that the smallest particle size of about 2.8 nm was synthesized when the ratio of surfactant/water/oil was 0.3450/0.0729/0.5821.

• Applied Chemistry for Engineering
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• v.28 no.2
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• pp.186-192
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• 2017

In this study, water in oil (W/O) emulsion fuel was prepared with surfactant mixture of OIMS90 and NP12 by varying ratio of water to bunker-C oil, surfactant concentration and composition, emulsification time, stirring intensity, temperature and mixing time. Diesel engine performance and exhaust emissions were measured and analyzed with prepared emulsified fuel and compared with those measured using bunker Coil. The results indicated that bunker C emulsion fuel stabilized by surfactant mixture of OIMS90 and NP12 is efficient in reducing emissions of particulate matter, $NO_2$, CO, $CO_2$ and $SO_2$. The biggest reduction in exhaust emission was achieved by using emulsion fuel prepared by OIMS90/NP12 = 4 : 6, 500 ppm of total surfactant concentration and 10% water content at $80^{\circ}C$. Boiler efficiency test measured with emulsion fuel showed excellent energy efficiency compared with bunker C oil.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.799-805
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• 2008

In general, anionic and cationic surfactants are incompatible because their mixtures form insoluble complexes and precipitate in the water. There are, however, some equimolar complexes of anionic and cationic surfactant that are soluble and behave like regular surfactants, specifically like nonionic surfactants, thus named pseudo-nonionic surfactant complexes. Pseudo-nonionic complexes are more effective and efficient in surface activities than their ionic surfactant components as shown by their equilibrium and dynamic surface tensions. They pack at the interface more than their ionic components. When a novel cationic surfactant, diglyceryl dodecyl dimethyl ammonium chloride(DGDAC), having the polyhydroxyl group at the hydrophilic head group, was mixed with a conventional anionic surfactant (sodium dodecyl sulfate; SDS) at equimolar ratio, we found that the aqueous equimolar mixture showed strong positive synergism in which molecular interaction parameter ${\beta}^M$ was very low, -17.2. According to the studies of equilibrium phase behavior and microscopy, this mixed system could form homogenous solutions containing vesicles.

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.274-284
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• 1994

Phase Inversion Temperature (PIT) measurements showed that the addition of polar components such as oleyl alcohol and oleic acid to the system comprising n-dodecylpentaoxyethylene monoether ($C_{12}E_5$), nonpolar oil (n-hexadecane) and water produced large reductions in the PIT. The PIT was lowered as the additive-to-surfactant ratio in the surfactant films in the microemulsion phase was increased. Another dramatic effect of additive was the manner in which it affects the volume of the microemulsion phase at the PIT of the oil and water solubilization characteristics. Microemulsion phase volume was increased rapidly with decreasing PIT, i.e., with increasing amounts of additive in the system. Also with a decrease in PIT, the solubilization parameters of both oil and water in the microemulsion phase were strikingly increased. Even though soil removal data were not available for the conditions where our results obtained, PIT measurement seems a useful starting point for estimating conditions when middle-phase microemulsion formation and its associated high solubilization of oil can be expected.

• Bulletin of the Korean Chemical Society
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• v.13 no.6
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• pp.647-649
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• 1992

The critical micelle concentration (CMC) values of cetylpyridinium chloride (CPC) in some alcohol-aqueous solutions were determined by UV-Vis spectroscopy at 25$25^{\circ}C$. The CMC of CPC was increased with the addition of methanol and ethanol, while with the addition of propanol it was decreased because of the solubilization of propanol into the micelle of CPC. The ratio (${\beta}$) of the number of counterions to that of surfactant ions associated into micelles in alcohol (methanol, ethanol and propanol) aqueous solutions was measured by using the Shinoda $equation^{17}$. The ratio of counterion binding to the CPC micelles in methanol-and ethanol-water mixtures was larger than in pure water, while the ratio in propanol-water mixture might be much decreased.

• Journal of Korea Soil Environment Society
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• v.2 no.1
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• pp.99-107
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• 1997

In this study, a series of batch-scale tests were conducted to optimize the design parameters for the application of soil washing techniques to the hydrophobic organic compounds(HOCs)-contaminated soil and to find the effective methods for the recovery of surfactants from washing effluent by using solvent. Several nonionic surfactants (polyoxyethylene oleyl ester) and sophorolipid were applied to the artificially contaminated soil (4,000 mg n-dodecane/kg dry soil). The effects of washing time, concentration of surfactant solution, dilution ratio, and temperature on washing efficiencies were examined. Hydrophile-liphophile balance (HLB) number was proven to be one of the important parameters for soil washing. The HLB numbers of OA-5 and sophorolipid are too low to form a stable soil-water emulsion. They showed very low washing efficiencies less than 10e1o. If HLB number is in the proper range to form a stable soil-water emulsion, surfactant having higher solubility for HOCs shows higher washing efficiency. OA-14 having higher HLB number than OA-9 formed more stable soil-water emulsion. But its washing efficiency was about 20% due to a lower molar solubility ratio (MSR) than OA-9. OA-9, which forms a stable soil-water emulsion and has comparatively high sotubility for HOCs, showed about 60% washing efficiency by itself. To recover anthracene effectively from OA-9 washing effluent by using benzene as an organic solvent, desirable temperature and pH were $30^{\circ}C$ and 2, respectively.

• Journal of Pharmaceutical Investigation
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• v.29 no.1
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• pp.37-45
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• 1999

ABSTRACT-A self-microemulsifying drug delivery system (SMEDDS) was developed to enhance the solubility and dissolution rate of poorly water soluble drug, biphenyl dimethyl dicarboxylate, DDB. The system was optimized by evaluating the solubility of DDB and the microemulsion existence range after the preparation of microemulsions with varying compositions of triacetin and surfactant-cosurfactant mixtures (Labrasol as surfactant (S) and the combination of Transcutol, Cremophor RH 40 and Plurol oleique as cosurfactant (CoS)). SMEDDS in this study markedly improved the solubility of DDB in water up to 10 mg/ml and the size of the o/w microemulsion droplets measured by dynamic light scattering showed a narrow monodisperse size distribution with an average diameter less than 50 nm. The microemulsion existing range is increased proportional to the ratio of S/CoS, however, it decreased remarkably as the oil content was more than 20%. In vitro dissolution study of SMEDDS showed a significantly increased dissolution rate of DDB in water (> 12 fold over DDB powder), and SMEDDS also had significantly greater permeability of DDB in Caco-2 cell compared to powders.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.3
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• pp.237-243
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• 2015

In this study, the effects of the mixing ratio of emulsified fuel on the droplet evaporation and spray behavior characteristics were analyzed. A surfactant comprising span 80 and tween 80 mixed at a 9:1 ratio was used for the emulsified fuel. The fuel and surfactant were mixed at a ratio of 3:1 for the emulsified fuel. In addition, considering the mixing ratio of the surfactant, the mixing ratio of $H_2O_2$ in the emulsified fuel was set as EF (emulsified fuel)0, EF2, EF12, EF22, EF32, and EF42. To observe the evaporation characteristics, droplets of the emulsified fuel were dropped on a heating plate and observed using scattered light and a Schlieren system. In addition, to analyze the effect of the $H_2O_2$ mixing ratio, the behavior characteristics of the evaporative free spray were investigated in the mixing ratio range of EF0 to EF22 using a constant volume chamber with heaters. Consequentially, it was found that in the case of EF22, the free spray development of the emulsified fuel was faster than that of EF0 (diesel only) because of the promotion of the evaporation due to the phase change in the peroxide contained in the emulsion fuel.

• Korean Journal of Materials Research
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• v.22 no.6
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• pp.298-302
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• 2012

Fe/$SiO_2$ core-shell type composite nanoparticles have been synthesized using a reverse micelle process combined with metal alkoxide hydrolysis and condensation. Nano-sized $SiO_2$ composite particles with a core-shell structure were prepared by arrested precipitation of Fe clusters in reverse micelles, followed by hydrolysis and condensation of organometallic precursors in micro-emulsion matrices. Microstructural and chemical analyses of Fe/$SiO_2$ core-shell type composite nanoparticles were carried out by TEM and EDS. The size of the particles and the thickness of the coating could be controlled by manipulating the relative rates of the hydrolysis and condensation reaction of TEOS within the micro-emulsion. The water/surfactant molar ratio influenced the Fe particle distribution of the core-shell composite particles, and the distribution of Fe particles was broadened as R increased. The particle size of Fe increased linearly with increasing $FeNO_3$ solution concentration. The average size of the cluster was found to depend on the micelle size, the nature of the solvent, and the concentration of the reagent. The average size of synthesized Fe/$SiO_2$ core-shell type composite nanoparticles was in a range of 10-30 nm and Fe particles were 1.5-7 nm in size. The effects of synthesis parameters, such as the molar ratio of water to TEOS and the molar ratio of water to surfactant, are discussed.