• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.59-65
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• 2008

The equilibrium solubilization capacity of the mixture of hydrocarbon oils by $C_{12}E_8$ nonionic surfactant micellar solution was measured at $23^{\circ}C$ by gas chromatography (GC) analysis. Experimental results indicated that the solubilization capacity for pure alkanes was found to decrease almost linearly with the alkane carbon number (ACN) of the hydrocarbon oil. For the binary mixture systems of the hydrocarbon oils both selective and nonselective solubilization behaviors were observed depending on the difference in ACN of the two hydrocarbon oils. Equilibrium solubilization tests for the hydrocarbon oil mixtures in $C_{12}E_8$ surfactant solutions such as the three n-octane/n-nonane, n-nonane/n-decane and n-decane/n-undecane mixture systems suggest almost non-selective solubilization. On the other hand, the n-octane/n-decane and n-octane/n-undecane systems, where difference in ACN of the two hydrocarbon oils is greater than 1, selective solubilization in favor of n-octane was conclusively demonstrated.

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.874-877
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• 2009

본 연구에서는 수용액 내의 오염물질 분해를 위하여 개발한 광촉매가 코팅된 실리카 비드의 광분 해반응 사용에 따른 활성저하 문제를 해결하기 위하여 반응에 사용한 비드의 활성을 향상시킬 수 있는 재생 방법에 관한 실험을 수행하였다. 비드의 재생방법으로 표면 세정법을 선택하였으며, 세정액으로는 물(증류수), 계면활성제, 아세톤 등 세정력이 서로 다른 3종의 용액을 사용하였다. 재생 과정은 서로 다른 3종의 세정액으로 반응에 사용하여 활성이 떨어진 비드를 세정한 후, 소성온도를 $100^{\circ}C$, $200^{\circ}C$, $300^{\circ}C$로 달리하여 30분간 처리하였다. 재생 처리과정은 각 1~3회 반복 수행하였으며, 서로 다른 조건에서 재생된 비드의 활성은 수용액 내의 methylene blue 광분해율로 측정하였다. 연구결과, 재생한 비드의 활성은 아세톤으로 세정한 후, $100^{\circ}C$에서 30분간 소성하였을 때 가장 우수한 것으로 나타났으며, 이러한 기초 연구결과를 토대로 현재보다 효율적인 재생 기술에 관한 연구를 수행 중에 있다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.8
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• pp.737-742
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• 2016

An elastomer (especially PDMS) sponge is considered to be a promising selective absorber in cleaning up oil spills. The performance of a PDMS sponge in capturing and separating oil from (sea) water depends on several parameters such as surface roughness, physicochemical treatments, and hydrostatic stability. Here, we first present a method of fabricating the PDMS sponges having numerous micro-sized pores that act as absorption and storage spaces for the target material, and then we report an experimental effort undertaken to control the surface physicochemistry (i.e., hydrophobicity or hydrophilicity) of the PDMS sponges by adjusting the size of the pores and the concentration of the surfactant (i.e., silwet L-77). From the experimental results, we develop an in-depth understanding of the mechanism for controlling the surface physicochemistry of PDMS using water-soluble micro-sized particles and a surfactant. The surface energy and absorbing behavior of the PDMS sponges are also extensively discussed.

• Journal of Soil and Groundwater Environment
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• v.6 no.4
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• pp.41-50
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• 2001

The use of clay has been the favored method of reducing or eliminating hazardous contaminants in the leachate from landfills. But, neither natural clays nor organoclays modified with surfactants are able to effectively sorb both heavy metals and organic contaminants. Therefore, the objective of this study is to determine the optimal amount of surfactant added on the clay mineral to effectively remove both of them. For this purpose, Na-Bentonite as the natural clay, and hexadecyltrimethylammonium (HDTMA) as the cationic surfactant were used, Chlorobenzene and lead ($Pb^{2-}$) were selected as representative contaminants. Experimental result showed that chlorobenzene sorption increased with increasing HDTMA to bentonite, ratios. On the contrary, the removal rate of lead decreased as the amount of HDTMA increased. The removal of chlorobenzene was influenced by the amount of HDTMA added to the bentonites rather than initial concentration of chlorobenzene, but the removal of lead was much more influenced by the initial concentration of lead. The adsorption of lead was not affected by chlorobenzene, and vice versa. The competitive sorption between the heavy metal and the organic contaminant was not present.

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.221-227
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• 1996

Micellization range and cmc for the dilute aqueous solution of N-acyl amino acid type anionic surfactants, that is, sodium N-acyl-N-methyl-${\beta}$-alaninate, sodium N-acyl sarcosinate and sodium N-acyl-N-methyl taurate were investigated by computer programming. The extreme of the curvature of ${\sigma}(C)$ as a new suggested method to determine the cmc and the micellization range was accomplished with computer programming. The values of cmc and micellization range can be obtained by the extreme of the curve by direct processing of only a few experimental data. The values of cmc particulary was in good agreement with those deduced intuitively from the shape of experimental curves of ${\sigma}(C)$.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.2
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• pp.199-208
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• 2019

This study reports water-resistant oil-in-water (O/W) emulsion-based sunscreening formulations prepared using a poly(ethylene glycol)-poly(${\varepsilon}$-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG) triblock polymeric surfactant. As a result of a variety of outdoor recreational activities such as swimming and hiking, consumer needs for development of advanced water-resistant sunscreen formulations are increasing. Water-resistant sunscreens are mostly based on water-in-oil (W/O) emulsions, because they should not be wiped off by water or sweat. However, the W/O emulsion formulations have a disadvantage in that the feeling of use is oily and difficult to remove. On the other hand, the O/W emulsion formulations are excellent in achieving the better skin feel as well as the easier removal. However, it is difficult to provide the O/W emulsion formulations with the water-repelling performance, since re-emulsification likely occurs upon getting touch with water. To solve this problem, this study proposes a O/W emulsion-based sunscreen formulation, a triblock polymeric surfactant having relatively high interfacial tension HLB value (~ 10). This allows the sunscreen formulations to exhibit the improved water repellence function by preventing their re-emulsification. The sunscreen formation system prepared in this study would be useful for diversification of functional sunscreen products, taking advantages of its excellent emulsion stability, UV protection performance, long lasting water-resistant function and selective cleansing effect with only foam cleanser.

• Journal of the Korean Magnetics Society
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• v.16 no.1
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• pp.102-106
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• 2006

Magnetic nanoparticles can be used for a variety of biomedical applications. They can be used in the targeted delivery of therapeutic agents in vivo, in the hyperthermic treatment of cancers. in magnetic resonance (MR) imaging as contrast agents and in the biomagnetic separations of biomolecules. We have synthesized magnetite $(Fe_3O_4)$ nanoparticles using chemical coprecipitation technique with sodium oleate as surfactant. Nanoparticle size can be varied from 2 to 8nm by controlling the sodium oleate concentration. Magnetite phase nanoparticles could be observed from X-ray diffraction. Magnetic colloid suspensions containing particles with sodium oleate and chitosan have been prepared. Nanoparticles, both oleate-coated and chitosan-coated, have been characterized by several techniques. Atomic farce microscope (AFM) was used to image the coated nanoparticles. Magnetic hysteresis measurement were performed using a superconducting quantum interference device (SQUID) magnetometer at room temperature to investigate the magnetic properties of the magnetite nanoparticles. The SQUID measurements revealed superparamagnetism of nanoparticles.

• Fire Science and Engineering
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• v.29 no.2
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• pp.79-83
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• 2015

The fire accident is a representative type of disaster that can largely impact on business. Therefore, precautionary measures and rapid initial response is very important when a disaster occurs. The storage of porous combustibles is inevitable in coal yard, plywood processing industry, and others that are currently operating. Initial fire fighting of fire and identifying the ignition point in such a porous combustible storage space are so difficult that if the initial response is failed, being led to deep-seated fire, surface fire is likely to result in secondary damage. In addition, deep-seated fire can cause personal injuries and property damage due to a large amount of toxic gases and reignition. Therefore damage reduction measures is required around the storage space to handle a porous flammable. Improving the penetration performance of the concentration of the surfactant is carried out as underlying study, which is about an deep-seated fire extinguishing efficiency augmentation when using wetting agents. The porous materials used in the experiments is radiata pine wood flour, which occupies more than 75% of the domestic wood market. Fire fighting water is selected as Butyl Di Glycol (BDG), which is being used for infiltration extinguishing agent, and the experiment was carried out by producing a standard solution. The experiment was carried out on the basis of the Deep-Seated Fire Test of NFPA 18. The amount of watering, porous material to the internal amount of penetration, and runoff measurement out of the porous material was conducted. According to experimental results, as the surface tension is reduced, the surfactant concentration macroscopic penetration rate decreases, but infiltration to a porous material is shown to have growth characteristics.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.2
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• pp.179-188
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• 2014

Purpose: The present study was aimed to investigate the cleaning efficacy of multi-purpose solutions containing different types and content of surfactants and their effect on the visible light transmittance of soft lens. Methods: Soft lenses made of different materials (etafilcon A and hilafilcon B) were deposited tear proteins by using the artificial tear and then compared the resulting cleaning efficacy and visible light transmittance after cleaning the lens with 6 types of multi-purpose solutions containing different content of surfactants. Results: The cleaning efficacy of multi-purpose solutions was variously shown as approximately 23~43% according to the active concentration of surfactants and surface tension in multi-purpose solution when etafilcon A lens cleaned with rubbing. The highest cleaning efficacy was detected when cleaned with the multi-purpose solution containing hydrogen peroxide besides surfactant however, the amount of remaining protein was still high on the lens. After washed with multi-purpose solution, the visible light transmittance of lens was in 89.8 to 90.8%. The amount of protein deposited on hilafilcon B lens was very small compared with it on etafilcon A lens even though it was incubated in artificial tears for 7 days, which showed 5~10% of protein amount in etafilcon A lens and the decrease of visible light transmittance was also not significant. In case of rubbing with multi-purpose solution, the cleaning efficacy on hilafilcon B lens was in 45.4 to 67.4% however, the order of cleaning efficacy of multi-purpose solution was different from it on etafilcon A lens. The visible light transmittance of hilafilcon B lens has been restored to the level of new lens. Conclusions: From the result, it is concluded that the appropriate multi-purpose solution should be selected according to the lens material and the amount of protein deposit on the basis of understanding surfactants and active principle for proper care of protein deposit on soft lens and the cleaning with rubbing is more efficient for lens care regardless of manufacturer's guideline.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3269-3273
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• 2009

In this study, recycling methods of nano $TiO_2$-coated silica-bead were conducted in order to solve a deactivation problem of bead that had been invented for decomposition of pollutants in aqueous solution. Surface cleansing was selected as the recycling method for used beads. The surface cleansing was done with four different solutions such as distilled water, surfactant, acetone, and ethyl alcohol(ethanol). The recycling process consists of cleansing and calcination. After cleaning the used (deactivated) beads, calcination was done at $100^{\circ}C$, $200^{\circ}C$ and $300^{\circ}C$ for 30 minutes, respectively. This process was repeated three times. The activity of the recycled bead was measured by photo-degradation of methylene blue. The result shows that acetone cleansing and calcination at $100^{\circ}C$ for 30 minutes was the most efficient recycling method.