• International Journal of Air-Conditioning and Refrigeration
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• 제8권2호
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• pp.1-10
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• 2000

This research is concerned with the enhancement of heat transfer by surfactant added to the aqueous solution of LiBr. Different vertical tubes were tested with and without an additive of normal octyl alcohol. The test tubes are a bare tube, a groove tube, a corrugated tube and a spring-inserted tube. The additive concentration is about 0.08 mass%. The heat transfer coefficient is measured as a function of the film Reynolds number in the range of 20~200. Experiments are carried out at higher cooling water temperature of $35^{\circ}C$to simulate an air cooling condition for several kinds of absorber testing tubes. The experimental results with and without surfactant are compared. The enhancement of heat transfer by Marangoni convection effect which is generated by addition of the surfactant is observed in each test tube. Especially, it is clarified that the tube with an spring-inserted has the enhancement effect.

• Bulletin of the Korean Chemical Society
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• 제13권5호
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• pp.486-491
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• 1992

The rate constants for the reactions of p-nitrophenyl acetate with 6 different aryloxides and 2 benzohydroxamates have been measured spectrophotometrically in water containing various concentrations of cetyltrimethylammonium bromide (CTAB). The reactivity of the nucleophiles has been demonstrated to be significantly enhanced as the concentration of the surfactant increases up to a certain point. When the basicities of the aryloxides are comparable, the rate enhancement is more prominent for the aryloxide having larger binding constant to the micellar aggregate. Benzohydroxamates exhibitis significantly large ${\alpha}$-effect in the absence of the surfactant, although, the ${\alpha}$-effect nucleophiles are considered to be more solvated in water than the corresponding normal nucleophile. Thus, the solvation effect does not appear to be solely responsible for the ${\alpha}$-effect. Interestingly, the large ${\alpha}$-effect disappears in the presence of the surfactant. Therefore, one might attribute the disappearance of the ${\alpha}$-effect to solvent effect. However, a structural change of the reactive ${\alpha}$ -effect nucleophile into unreactive ones would also be considered to be responsible for the absence of the ${\alpha}$-effect in the present system.

• Journal of Pharmaceutical Investigation
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• 제28권4호
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• pp.249-255
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• 1998

Solid Lipid Nanoparticle(SLN), one of the colloidal carrier systems, has many advantages such as good biocompatibility, low toxicity and stability. In this paper, the effects of drug lipophilicity and surfactant on the drug loading capacity, particle size and drug release profile were examined. SLNs were prepared by homogenization of melted lipid dispersed in an aqueous surfactant solution. Ketoprofen, ibuprofen and pranoprofen were used as model drugs and tweens and poloxamers were tested for the effect of surfactant. Mean particle size of prepared SLNs was ranged from 100 to 150nm. The drug loading capacity was improved with the most lipophilic drug and low concentration of surfactant. Particle size and polydispersity of SLNs were changed according to the used lipid and surfactant. The rates of drug release were controlled by the loading drug and surfactant concentration. SLN system with effective drug loading efficiency and proper particle size for the intravenous or oral formulation can be prepared by selecting optimum drug and surfactant.

• 한국응용과학기술학회지
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• 제25권1호
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• pp.23-31
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• 2008

In general, anionic and cationic surfactants are incompatible because their mixtures form insoluble complexes. There are, however, some complexes 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 than their ionic surfactant components as shown by their equilibrium and dynamic surface tensions and interfacial tensions. They pack at the interface more than their ionic components. Since, pseudo-nonionic complexes show their own characteristics, they can be treated as separate classes of surfactants distinct from ionic and nonionic surfactants. Novel cationic surfactant was synthesized, having the polyhydroxyl group at the head group. We found that aqueous mixtures of our cationic surfactant and usual anionic surfactant(SDS) could form homogeneous solutions even at high concentration. The properties of mixed surfactant solutions were measured. Foam stability, CMC(critical micelle concentration), water hardness tolerance and thickening effect were tested. The foam stability of mixed surfactants was very good and various synergy effects were observed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.1288-1291
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• 2004

In this study, physical characteristics of alumina slurry on variation of pH value and the effect of non-ionic surfactants on alumina slurry for copper chemical mechanical planarization (CMP) slurry have been investigated. After pH value of the slurry with alumina abrasive was changed by adding various amount of $HNO^3$ or KOH, the differences of settling rate, particle size, and zeta-potential were estimated. Better settling rates were shown in slurries with alumina abrasive at near pH 1. Higher zeta-potential was shown at around pH 2 in alumina slurry and the point of zero charge (PZC) was measured at about pH $9\sim10$. Non-ionic surfactant was added in the slurry with 5wt% alumina abrasive to get its effect on slurry practically. Abrasive size was smaller increased when amount of surfactant increased in slurry with P-4 as abrasive; on the other side, it was smaller when amount of surfactant decreased with AES-12. Variation of zeta-potential has no tendency with adding surfactant; however, values of zeta-potential were between $35\sim50mV$. The proper amount of surfactant was $0.1\sim1.0wt%$ in slurry with P-4 and $0.5\sim1.0wt%$ in slurry with AES-12 respectively. Excellent dispersion stabilization was obtained by addition of non-ionic surfactant

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.346-349
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• 2004

Surfactant-enhanced electrokinetic (EK) process was investigated to remove polycyclic aromatic hydrocarbons (PAHs) from low-permeable soils. Phenanthrene and kaolinite were selected as a representative PAH and a model soil, respectively. A nonionic surfactant Tergitol 15-S-12 was applied to improve the solubility of phenanthrene and sodium chloride was used as an electrolyte at the various concentrations from 0.001 to 0.1M. The addition of electrolyte affected both the removal efficiency and operation cost. When electrolyte was introduced, the electrical potential gradient became low and thus power consumption was reduced. However, as electrolyte concentration increased, the electroosmotic flow also decreased, so the removal efficiency of contaminant decreased. Therefore, the removal efficiency and power consumption should be considered simultaneously to determine the iptimum surfactant concentration, so a relatively lower concentration of electrolyte than certain value is desired.

• International Journal of Industrial Entomology and Biomaterials
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• 제28권1호
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• pp.19-24
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• 2014

Silk has always been one of the most favored textile materials. Fully degummed silk fiber (i.e., silk fibers without sericin) shows better luster than raw silk fiber (with sericin); it is also softer. On the other hand, raw silk fiber feels cooler because of the presence of sericin, making it useful as a textile for the summer season. Recently, partially degummed silk has attracted researchers' attention because it provides better luster, feel, and dyeing properties. However, the partial degumming of silk is very difficult because it results in inhomogeneously degummed fiber. In the present study, silk yarns were degummed with surfactant aqueous solutions and the effects of each surfactant on the degumming ratio, crystallinity, and homogeneity of the degummed silk yarn were examined. The degumming ratio and crystallinity index of silk yarn varied depending on the type of surfactant. On the whole, anionic surfactants resulted in higher degumming ratios and better homogeneity than nonionic surfactants.

• Macromolecular Research
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• 제13권5호
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• pp.385-390
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• 2005

The electrospinning process is a fascinating method to fabricate small nanosized fibers of diameter several hundred nanometers. Surfactant-polymer solutions were prepared by adding poly(vinyl alcohol) (PVOH) to distilled water with cationic, anionic, amphoteric, and non-ionic surfactants. Average diameter of the electrospun PVOH fibers prepared from PVOH solution was over 300 nm, and was decreased to 150 nm for the mixture of PVOH/amphoteric surfactant. To explain the formation of ultra fine fiber, the characteristic properties in a mixture of PVOH/surfactant such as surface tension, viscosity, and conductivity were determined. In this paper, the effect of interactions between polymers with different classes of surfactants on the morphological and mechanical properties of electrospun PVOH nonwoven mats was broadly investigated.

• Archives of Pharmacal Research
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• 제15권2호
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• pp.126-129
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• 1992

The critical micelle concentrations (CMCs) of aqueous solutions of a nonionic surfactant, polyoxyl 23 lauryl ether in the presence of various concentration of urea and its derivatives were measured. The CMC of the surfactant increase in proportion to the concentration of the additives, and the CMC-raising activities increased with more and longer alkyl grups substituted in urea. The CMC shift values were successfully correlated with the cloud point shift values and the protein-denaturing activities of the additives, respectively. These results suggest that the micelle formation, clouding of the surfactant and the protein denaturation are a closely related phenomenon, and a common mechanism is operating which might be the hydrophobic interaction.

• Korean Chemical Engineering Research
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• 제47권1호
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• pp.38-45
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• 2009

본 연구에서는 섬유 유연제, 분산제, 대전방지제, 표백 활성제, 유화제 등으로 널리 사용되고 있는 이미다졸린 양이온 계면활성제의 계면 특성을 측정하였다. 계면활성제의 CMC는 약 $6{\times}10^{-5}mol/L$ 이고 CMC에서의 표면장력은 약 32 mN/m이며, 또한 이미다졸린 계면활성제의 표면장력은 계면활성제 농도에 관계없이 비교적 일정하고, 일정한 계면활성제 농도 조건 하에서 수용액의 pH가 증가하면 표면장력은 감소하였다. 1 wt% 계면활성제 수용액과 n-dodecane 오일 사이의 계면장력은 약 0.01 mN/m이고 평형에 도달하는 시간은 pH에 관계없이 거의 일정하였다. $30{\sim}60^{\circ}C$ 의 온도 범위에서 계면활성제 수용액은 pH에 관계없이 마이셀 수용액의 $L_1$만을 형성하였고 계면활성제-물-오일로 이루어진 3성분 시스템은 lower phase 마이크로에멀젼을 포함한 2상 영역만이 존재하였다. 1 wt% 계면활성제 수용액의 거품 안정성은 수용액의 pH가 증가할수록 증가하며, 이러한 결과는 pH가 증가함에 따라 1 wt% 계면활성제의 표면장력이 감소하는 결과와 일관된 경향을 나타내었다. QCM(quartz crystal microbalance) 측정에 의하면 계면활성제 흡착은 농도 증가에 따라 증가하며, pH 증가에 따라 감소하였다. 또한 마찰 계수 측정으로부터 수용액의 pH가 알칼리 조건 하에서 이미다졸린 양이온 계면활성제의 섬유 유연 효과가 가장 우수함을 알 수 있었다.