• 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.

• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.31-37
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• 2009

A zwitterionic surfactant shows not only detergency but also mildness effect since it shows characteristics of a nonionic or an anionic surfactant above an isoelectric point, while showing characteristics of a cationic surfactant below an isoelectric point. Therefore, a zwitterionic surfactant can serve as a dual function surfactant by a single molecule through the interconversion of cleaning and softening effects depending on pH variations of the aqueous solution. In this study, physical properties of betaine surfactant such as CMC, surface tension, interfacial tension, contact angle and viscosity were measured and phase behavior study was performed. Also dual function characteristics of betaine zwitterionic surfactant were investigated by measuring an isoelectric point using QCM(quartz crystal microbalance) and zeta potential measurement. The CMC of betaine surfactant was near $10^{-4}mol/L$ and the surface tension at CMC was about 32 mN/m. The interfacial tension between 1 wt% aqueous solution and n-decane measured by spinning drop tensiometer at pH 2~10 resulted in an increase in interfacial tension until pH 5 and a decrease with pH after 5 and equilibration time showed the similar trend with an increase in pH. The isoelectric point of betaine surfactant measured by QCM experiment was found to exist between 3.0 and 3.3, which is the same as the result determined by zeta potential measurement.

• Journal of Adhesion and Interface
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• v.13 no.4
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• pp.182-187
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• 2012

In making emulsion-type pressure sensitive adhesive (PSA), environmentally friendly sorbitan nonionic surfactants having various chemical structures were prepared and used to find out the possibility of substituting the traditional nonyl-phenyl nonionic surfactant (NPE40) by comparing their adhesive properties. Results exhibited that the PSA used NSR10-series and Tween 60 showed better adhesive properties in initial ball tack, peel strength and holding power than those of NPE40. The reason for this is their particular chemical structure and the proper ratio of hydrophobic groups to the ethylene oxide groups.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.10a
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• pp.137-139
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• 1998

계면활성제는 섬유, 의약품, 화장품, 식품, 조선, 토목, 건축, 광업, 가정용 세제 등 인간생활에 폭넓게 이용되고 있다. 계면활성제의 사용범위가 넓어짐에 따라 계면활성제 자체의 오염성 때문에 분리대상 물질이나 재사용을 위한 회수물질로 간주되고 있다. 특정물질의 분리$\cdot$회수를 위한 분리막 기술은 공정이 간단하고 상변화를 수반하지 않으므로 에너지 소모가 작은 장점들을 가지고 있어 폐수처리, 수처리, 대기오염 방지등에 이용되고 있다. 본 연구에서는 비교적 소수기가 짧아서 저온에서도 잘 녹고, 세정성이 양호하여 세제, 유화제, 섬유제품의 침투제로 널리 이용되고 있는 음이온 계면활성제 SDS와 SLS용액의 한외여과에 대한 투과실험을 수행하였다. 또한 음이온 계면활성제와 인체에 유해한 금속이온($Cd^{++}, Cu^{++}, Zn^{++}$) 혼합물에 대한 제거실험을 실시하였다.

• Journal of Korea Soil Environment Society
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• v.4 no.2
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• pp.77-86
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• 1999

Partitioning of two hydrophobic organic compounds (HOCs), phenanthrene and naphthalene, to kaolinite and sorbed surfactants was studied to evaluate the feasibility of surfactant-enhanced remediation (SER) of contaminated subsurface systems. Sorbed surfactant partition coefficients. $K_ss$, showed a strong dependence on the surfactant sorption isotherms at low sorbed surfactant levels $K_ss$ values were at their highest and then decreased with increasing surfactant sorption densities. $K_ss$ values for SDS were always larger than corresponding $K_mic$values. For Tween 80, however. $K_ss$ values $K_mic$ were higher than $K_mic$ values only at the lower sorbed surfactant densities. HOC distribution between immobile and mobile phases varied with surfactant dose distribution coefficients increased initially with increasing surfactant concentrations and then decreased at higher doses. This observation shows directly the competition between sorbed and micellar surfactants for HOC partitioning. Overall results of this study demonstrate that surfactant sorption to the solid phase can lead to increases in HOC retardation in some SER applications. Therefore, before an SER process is selected, appropriate consideration of surfactant sorption and HOC partitioning to immobile versus mobile phases pertinent to a specific subsurface system must be contemplated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.7
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• pp.695-701
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• 2013

The suppression of a thermocapillary flow (Marangoni flow) by a nonionic surfactant is experimentally investigated for evaporating pure water droplets on hydrophobic substrates. The experiment shows that as the initial concentration of the surfactant increases, the velocity and lifetime of the flow monotonically decrease. The result confirms the no-slip boundary condition at a liquid-air interface, which is explained on the basis of the previous model regarding the effect of surfactants on the no-slip condition. Interestingly, at an initial concentration much less than a critical value, it is found that depinning of the contact line occurs during the early stage of evaporation, which is ascribed to a reduction in the contact angle hysteresis owing to the presence of the Marangoni flow.

• Korean Chemical Engineering Research
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• v.50 no.2
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• pp.282-291
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• 2012

The PGLE and PGLE3 nonionic surfactants were synthesized from the reaction between glycidol and lauryl acid and their structures were confirmed by $^1H$ and $^{13}C$ NMR analysis. The CMCs of PGLE and PGLE3 surfactants were found to be $3.59{\times}10^{-2}$ mol/L and $8.80{\times}10^{-2}$ mol/L respectively and the surface tensions at their CMC conditions were 26.09 mN/m and 28.68 mN/m respectively. Dynamic surface tension measurement has shown that the adsorption rate of surfactant molecules at the interface between air and surfactant solution was found to be relatively fast in both surfactant systems, presumably due to high mobility of surfactant molecules. The contact angles of PGLE and PGLE3 nonionic surfactants were $25.5^{\circ}$ and $9.5^{\circ}$ respectively. Dynamic interfacial tension measurement showed that both surfactant systems reached equilibrium in 20 minutes and the interfacial tensions at equilibrium condition in both systems were 0.42 mN/m and 0.53 mN/m respectively. The PGLE surfactant system has indicated higher foam stability than the PGLE3 surfactant system, which is consistent with surface tension measurement. The phase behavior experiments performed at $25{\sim}60^{\circ}C$ in systems containing nonionic surfactant, water, n-hydrocarbon oil and cosurfactant showed a lower phase or oil in water microemulsion in equilibrium with excess oil phase at all conditions investigated during this study.

• Elastomers and Composites
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• v.36 no.4
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• pp.246-254
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• 2001

In this work, the stabilization of chlorosulfonated polyethylene (CSM) rubber emulsion with surfactants, i.e., nonionic (Span 60) or anionic (Sodium laurylsulfate, SLS) surfactants, was investigated. The phase inversion emulsification by interfacial chemical characteristics was used to emulsify the CSM rubber. As a result, the emulsion phase separation was observed in the case of any single surfactant. However, there was no phase separation in the mixture of Span 60 and SLS in the context of emulsion droplet size tests and rheological behaviors. The droplet size decreases by increasing the surfactant mixture, resulting in increasing the viscosity. The viscosity and shear stress determined from shear rate show a shear thinning and yield behaviors. It was then found that the emulsion stabilization can be improved using the phase inversion emulsification method and surfactant mixture.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.524-532
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• 2018

In this study, two types of amino acids-based anionic biosurfactants such as potassium cocoyl glutamate (CTK) and sodium cocoyl glutamate (CTN) were synthesized from coconut oils and the structure elucidation of CTK and CTN was carried out by using FT-IR, $^1H-NMR$ and $^{13}C-NMR$ spectrophotometries. Measurements of interfacial properties such as static and dynamic surface tensions and emulsification activity showed that both CTK and CTN were surface-active and effective in lowering the interfacial free energy. In particular, the CTK surfactant was found to be more efficient in reducing the interfacial free energy since the larger number of CTK molecules was preferentially adsorbed at the air-water interface due to the higher hydrophobicity and larger mobility of CTK than those of using CTN, indicating possible uses in cosmetics and household products formulation.

• Journal of Korea Soil Environment Society
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• v.3 no.2
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• pp.115-125
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• 1998

The biodegradation of ($C^{14}$)phenanthrene was studied in water and soil-water systems with nonionic surfactants and biosurfactant : polyoxyethylene alkyl ester($C_{17}$$H_33$COO($C_2$$H_4$O)nH) and sophorolipid. The extents of so1ubilization and biodegradation were monitored by radiotracer technique. Experimental results showed that surfactant concentrations above the critical micelle concentration were toxic to the phenanthrene-degrading bacteria in soil or active sludge and the presence of surfactant micelles inhibited mineralization of PAHs. Solubility and bioavailibility of phenanthrene in water and soil-water system were enhanced by mixed surfactants system. The optimum water content and hydrogen concentration were 30% (w/v) , pH 7, respectively.