• Applied Chemistry for Engineering
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• v.4 no.2
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• pp.423-431
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• 1993

Long chain alcohols, the mixtures of 1-hexadecanol/1-octadecanol, were used as cosurfactants for O/W emulsion prepared with glycerol monostearate/POE(100) monostearate mixed nonionic surfactants, and the phase behavior and flow properties of O/W emulsions were observed. The transition temperature of long chain alcohol was varied with the composition of 1-hexadecanol/1-octadecanol and had the lowest value when the mixed ratio of 1-hexadecanol/1-octadecanol was 2/1. The liquid crystalline phase was formed as the addition of long chain alcohol and the secondry droplet, the flocculate of the emulsion particles, was made, and thus the viscosity of the emulsion was increased. When the temperature of emulsion system was under the transition temperature of long chain alcohol, the mobility of hydrocarbon group of long chain alcohol was restricted, and thus gel structure was formed and the viscosity of the the O/W emulsion was increased, but along with the time, the liquid crystalline phase was disappeared and the viscosity of emulsion was decreased. Long chain alcohol/nonionic surfactants/water formed the liquid crystalline phase when the long chain alcohol was added above the saturation point of solution(2 wt% in this experoment), and the secondry droplet didn't formed when the long chain alcohol was added more than a certain amount (10 wt% in this experiment).

• Journal of the Korean Applied Science and Technology
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• v.25 no.2
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• pp.205-210
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• 2008

The transformation of the liquid crystal complex made by binding of anionic surfactant, sodium dodecyl sulfate (SDS), into high charge density cationic polymer, the homopolymer of diallyldimethylammonium chloride (PDADMAC) was induced by adding of nonionic surfactants and investigated by means of microscopy and FE.SEM. Among nonionic surfactants in this experiments polyethylene glycol (3 mol) ether of lauryl alcohol (laureth-3) made variation in the complex. The laureth-3 transformed the complex into spherulite vesicle with the size of ca.$100{\mu}m$. This change increased the viscosity and the turbidity of the solution phase separated originally. Microscope showed that they are spherulite particles and polarized microscope suggested they are multi.lamellar liquid crystals. FE-SEM also proved that explicitly.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.20-26
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• 2014

The interaction of p-halogenated phenol derivatives with the micellar system of tetradecyltrimethylammonium bromide (TTAB) was studied by the UV/Vis spectrophotometric method. Effects of substituents, additives, and temperatures on the solubilization of phenol derivatives have been measured. The results show that all the values of ${\Delta}G^o$ and ${\Delta}H^o$ were negative and the values of ${\Delta}S^o$ were positive for all phenol derivatives within the measured temperature range. The calculated thermodynamic parameters depended on the size, the electro-negativity, and the hydrophobic property of halogen substituents. The addition of n-butanol results in the decrement in tthe Ks values and the addition of NaCl caused the increment in the Ks values for all the phenol derivatives. From these changes we can postulate that the solubilization sites of the phenol derivatives in the micelle depend severely on properties of the halogen-substituent.

• Journal of the Korean Applied Science and Technology
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• v.32 no.3
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• pp.461-468
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• 2015

Simultanious quantitative determination of Cetyltrimetyl ammonium chloride(CTM), Stearamidopropyl dimetylamine(SAP), Behentriammonium chloride(BHT), Dihexadeyldimethyl ammonium chloride(DHDDM) was carried out by reversed phase HPLC. The 0.2% TFA/Methanol was used for the mobile phase of gradient conditions. An Alltech $C_{18}$($250mm{\times}4.6mm$ i.d., $5{\mu}m$)and the selected ELSD detector was applied. The analysis results of HPLC showed good linearity with correlation coefficient of $r^2=0.997$ in the rage of $130{\sim}1980.5{\mu}g/mL$ and detection limit.

• Journal of Soil and Groundwater Environment
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• v.6 no.3
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• pp.21-29
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• 2001

Organobentonite modified with hexadecyltrimethylammonium (HDTMA) was used to quantify adsorption of heavy metals. Adsorption of cadmium and lead increased with increasing pH and soil/solution ratio. Based on these experiments, an optimal soil/solution ratio and an optimal pH was selected. Adsorption experiments with cadmium and lead were conducted to quantify adsorption selectivity on bentonite and organobentonite. Adsorption of heavy metals on organobentonite was slightly reduced relative to bentonite. Because of competition between cadmium and lead, adsorption of each metal was reduced due to the presence of the other. Adsorption selectivity of cadmium was higher than lead. This study used the principle of hard soft-acid-base (HSAB) to interpret adsorption.

• Membrane Journal
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• v.15 no.1
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• pp.34-43
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• 2005

The poly(vinyl alcohol) (PVA)-based thin film composite nanofiltration (NF) membranes were prepared by coating polysulfone ultrafiltration membranes, sulfonated polyethersulfone and polyamide NF membranes with aqueous PVA solution by a pressurizing method. The PVA was cross-linked with aqueous glutaraldehyde solution. The NF membranes coated with a very low concentration of PVA on all the support membranes was successfully prepared. With increasing the hydrophilicity of the support membranes, the water flux increased. Especially, ζ-potential of negatively charged polyamide NF membrane was reduced by coating the membrane with PVA. A fouling experiment was carried out with positively charged surfactant, humic acid, complex of humic acid and calcium ion and bovine serum albumin. A non-coated polyamide NF membrane was significantly fouled by various foulants. The fouling process when using humic acid and protein occurred at the isoelectric point. There was severe fouling when using humic acid and adding bivalent cations. By coating the polyamide NF membrane with aqueous PVA solution, fouling was reduced. The polyamide NF membrane coated with PVA was resistant to the acidic and basic solution.

• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.116-124
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• 2017

A plate-type inorganic pigment complex was manufactured in a manner that treats the surface of the complex by adjusting zeta potential between talc, an inorganic pigment used as a material for color cosmetics, and hydrophobic silica. Talc, which is usually used in the prescription of color cosmetics, is a plate-type, white-colored inorganic substance with good application and spreadability to skin. Furthermore, it features excellent dispersibility and extensibility as well as outstanding heat tolerance, light stability, and chemical resistance. In general, silica contributes to durable makeup and stabilized formulation. This paper covers a process of manufacturing an inorganic pigment complex, where hydrophobic silica was applied to the surface of talc by using differences in zeta potential after the surface charges of talc and hydrophobic silica had been adjusted with cationic and anionic surfactants, respectively. The resulting inorganic pigment complex was composed of talc whose surface is coated hydrophobic silica to the thickness of $1{\mu}m$ or less, which developed an effective hydrophobic property. Zeta potential was measured to analyze the surface charge of an inorganic pigment, and FT-IR, used to check the functional group of a surfactant, was applied to treat the surface of the pigment. The surface of the inorganic pigment complex was observed employing SEM, EDS, and FIB, while its structure was confirmed with XRD and FT-IR.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.8
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• pp.873-876
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• 2012

Ionic liquids (ILs) existing in the liquid ion form under standard conditions show a unique properties. 1-10-Alkyl-3-methyl-imidazolium bromide ([C10mim][Br]) is one of the ILs that shows amphiphilic characteristics under specific conditions. This property enables it to function as a surfactant, and therefore, it finds applications in a wide range of areas. In this study, we tried to predict the behavior, especially the aggregation aspect, of [C10mim][Br] in an aqueous solution using molecular dynamics (MD) simulations. The canonical (NVT) ensemble was used to relax the system and trace the trajectory of atoms. Several case studies were simulated and the interaction among [C10mim]+, [Br]-, and water was analyzed using the radial distribution function of each atom. The density distribution function was also used for the structural analysis of the entire system. We used the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code for the present MD simulations.

• Journal of the Korean Institute of Gas
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• v.27 no.1
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• pp.23-32
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• 2023

In this study, the Al₂O₃ nanofluid was synthesized as an additive for improving the injection efficiency and storage capacity of carbon dioxide (CO₂) in a depleted sandstone reservoir or deep saline aquifer. As the base fluid, deionized water (DIW) and saline prepared by referring to the composition of API Brine were used, and the fluid was synthesized by using Al₂O₃ nanofluid with CTAB (cetyltrimethyl-ammonium bromide), a cationic surfactant. After that, the dispersion stability was evaluated by using visual observation, dynamic light scattering (DLS), transmission electron microscope (TEM), and miscibility test. As a result, it was presented that stable nanofluid without agglomeration and precipitation after reaction with 70,000 ppm of brine could be synthesized when the nanoparticle concentration was 0.05 wt% or less.

• Journal of the Korean Chemical Society
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• v.40 no.12
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• pp.724-732
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• 1996

The organic precipitate flotation using Cu(II)-pyrrolidinedithiocarbamate complex as a coprecipitant was studied for the preconcentration and determination of trace Cd, Pb, Bi and Co in several water samples. Experimental conditions such as pH of solution, amounts of Cu(II) and ammonium pyrrolidinedithiocarbamate(APDC), stirring time, the type and amount of surfactant, etc. were optimized for the effective flotation of analytes. After 3.0 mL of 1,000 ${\mu}g/mL$ Cu(II) solution was added to 1.00 L water sample, the pH of the solution was adjusted to 2.5 with HNO3 solution. Trace amounts of analytes were coprecipitated by adding 2.0% APDC solution. And the precipitates were flotated onto the surface of solution with the aid of nitrogen gas and sodium lauryl sulfate. The floats were collected from mother liquor, and filtered through the micropore glass filter by suction. The precipitates were dissolved with 4 mL conc. HNO3, and then diluted to 25.00 mL with deionized water. The analytes were determined by graphite furnace atomic absorption spectrophotometry. This flotation technique was applied to the analysis of some water samples, and the 90 to 120% of recoveries were obtained from the spiked samples, this procedure could be concluded to be simple and applicable for the trace element analysis in various kinds of water.