• Bulletin of the Korean Chemical Society
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• v.22 no.9
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• pp.1009-1014
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• 2001

In aqueous mixtures of cationic OTAC (octadecyl trimethyl ammonium chloride) and anionic ADS (ammonium dodecyl sulfate) surfactants, mixed micelles were formed at low (< 0.2 wt %) total surfactant concentrations. For these mixtures mixed micelliza tion and interaction of surfactant molecules were examined. Mixed critical micelle concentration (CMC), thermodynamic potentials of micellization, and minimum area per surfactant molecule at the interface were obtained from surface tensiometry and electrical conductometry. The mixed micellar compositions and the estimation of interacting forces were determined on the basis of a regular solution model. The CMCs were reduced, although not substantial, and synergistic behavior of the ADS and OTAC in the mixed micelles was observed. The CMC reductions in this anionic/cationic system were comparable to those in nonionic/anionic surfactant systems. The interaction parameter $\beta$ of the regular solution model was estimated to be -5 and this negative value of $\beta$ indicated an overall attractive force in the mixed state.

• Bulletin of the Korean Chemical Society
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• v.25 no.3
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• pp.382-388
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• 2004

The sizes and structures of micelles formed in aqueous solutions of cationic octadecyl trimethyl ammonium chloride (OTAC) and anionic ammonium dodecyl sulfate (ADS) surfactants were investigated using smallangle neutron scattering (SANS), self-diffusion coefficients by pulsed-gradient spin-echo (PGSE) NMR, and dynamic light scattering (DLS) methods. SANS and DLS data indicate that their structures are spherical at concentrations as high as 300 mM. As the total surfactant concentration increases, the peaks of SANS spectra shift to higher scattering vector and become sharper, indicating that the intermicellar distance decreases and its distribution becomes narrower. This is due to more compact packing of surfactant molecules at high concentrations. The intermicellar distance of around 100 ${\AA}$ above 200 mM corresponds approximately to the diameter of one micelle. The sizes of spherical micelles are 61 ${\AA}$ and 41 ${\AA}$ for 9 mM OTAC and 10 mM ADS, respectively. Also the self-diffusion coefficients by PGSE-NMR yield the apparent sizes 96 ${\AA}$ and 31 ${\AA}$ for micelles of 1 mM OTAC and 10 mM ADS, respectively. For ADS solutions of high concentrations (100-300 mM), DLS data show that the micelle size remains constant at $25{\pm}2{\AA}$. This indicates that the transition in micellar shape does not take place up to 300 mM, which is consistent with the SANS results.

• Korean Journal of Microbiology
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• v.20 no.4
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• pp.183-188
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• 1982

The neurotoxin of Clostridium botulinum type B was purified from a liquid culture. The purification steps consist of ammonium sulfate precipitation of whole culture, treatment of Polymin P(0.15%, v/v), gel filtration on Sephadex G-100 at pH5.6 and DEAE-Sephadex charomatography at pH8.0. The procedure recovered 17% of the toxin assayed in the starting culture. The toxin was homogeneous by sodium dodecyl sulfate(SDS)-polyacrylamide gel electrophoresis and had a molecular weight of 163, 000. Subunits of 106, 000 and 56, 000 molecular weight were found when purified toxin was treated with a disulfide-reducing agent and electro phoresed on SDS-polyacrylamide gels.

• Korean Journal of Microbiology
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• v.13 no.2
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• pp.71-80
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• 1975

The neurotoxin of Clostridium botulinum type B was purified from a liquid culture. The purification steps consist of ammonium sulfate precipitation of whole culture, treatment of Polymin P(0.15%, v/v), gel filtration on Sephadex G-100 at pH5.6 and DEAE-Sephadex charomatography at pH8.0. The procedure recovered 17% of the toxin assayed in the starting culture. The toxin was homogeneous by sodium dodecyl sulfate(SDS)-polyacrylamide gel electrophoresis and had a molecular weight of 163,000. Subunits of 106,000 and 56,000 molecular weight were found when purified toxin was treated with a disulfide-reducing agent and electro phoresed on SDS-polyacrylamide gels.

• Journal of the Korean Applied Science and Technology
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• v.19 no.4
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• pp.339-348
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• 2002

Self-diffusion coefficients of colloidal ass9Ciation structures in the aqueous solutions of anionic ammonium dodecyl sulfate (ADS) and cationic octadecyltrimethylammonium chloride (OTAC) surfactants were measured by pulsed-gradient spin echo NMR. The results were interpreted on the basis of the ADS/OTAC/water phase diagram. Crossing the phase boundaries, significant changes in self diffusion coefficients were observed and well correlated to the phase diagram. For the micelles their apparent radii were obtained from Stokes-Einstein equation. Their values were 15 for the ADS micelles and 54 ${{\AA}}$ for the OTAC micelles, respectively. For vesicles which were formed spontaneously at different relative amounts of the surfactants and total surfactant concentrations, the radius was measured as 50 to 200 nm. This result is in fair agreement with those by TEM and light scattering.

• Journal of the Korean Electrochemical Society
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• v.13 no.3
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• pp.163-168
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• 2010

Effects of Cetyl Trimethyl Ammonium Bromide (CTAB), which is a kind of cationic surfactants, and Sodium Dodecyl Sulfate (SDS), which is a kind of anionic surfactants on the anodic formation of nanoporous niobium oxide were compared. The addition of SDS could protect the surface from dissolution for long time, leading to the formation of niobium oxide with a double thickness (~400 nm) compared to that prepared without surfactant, whereas dissolution seriously occurred in the solution containing CTAB. The different behaviors were attributed to the interaction between the surfactants with positive (or negative) charge and positively charged niobium oxide.

• Bulletin of the Korean Chemical Society
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• v.28 no.4
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• pp.667-674
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• 2007

Phase behavior for the mixed aqueous surfactant systems of cationic octadecyl trimethyl ammonium chloride (OTAC)/anionic ammonium dodecyl sulfate (ADS)/water was examined. Below the total surfactant concentrations of 1.5 m molal, mixed micelles were formed. At the total surfactant concentrations higher than 1.5 m molal, there appeared a region where mixed micelles and vesicles coexist. As the surfactant concentration increased, the systems looked very turbid and much more vesicles were observed. The vesicles were spontaneously formed in this system and their existence was observed by negative-staining transmission electron microscopy (TEM), small-angle neutron scattering (SANS) and encapsulation efficiency of dye. The vesicle region was where the molar fraction α of ADS to the total mixed surfactant was from 0.1 to 0.7 and the total surfactant concentration was above 5 × 10-4 molality. The size and structure of the vesicles were determined from the TEM microphotographs and the SANS data. Their diameter ranged from 450 nm to 120μm and decreased with increasing total surfactant concentration. The lamellar thickness also decreased from 15 nm to 5 nm with increasing surfactant concentration and this may be responsible for the decrease in vesicle size with the surfactant concentration. The stability of vesicles was examined by UV spectroscopy and zeta potentiometry. The vesicles displayed long-term stability, as UV absorbance spectra remained unchanged over two months. The zeta potentials of the vesicles were large in magnitude (40-70 mV) and the observed longterm stability of the vesicles may be attributed to such high ζ potentials.

• Microbiology and Biotechnology Letters
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• v.20 no.2
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• pp.169-177
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• 1992

An alkaline protease producing microorganism was isolated from soil and identified as Streptomyces griseus HC-1141. The optimum culture condition of Streptomyces griseus HC- 1141 for the production of alkaline protease was as follows; 0.5% casein, 0.05% ammonium chloride, 0.1% ferrous sulfate. 2.0% lactose, pH 8.0 and 84 hrs. The enzyme was purified about 53 folds by ammonium sulfate treatment, DEAE-cellulose ion exchange chromatography and gel filtratioo on Sephadex G-150. The homogeneity of the purified enzyme was verified by polyacrylamide gel electrophoresis. The molecular weight was estimated to be 31,000 on sodium dodecyl sulfate polyacrylamide gel electrophoresis. This enzyme consists of glycine and glutamic acid as major amino acids. The N-terminal and C-terminal residues of the alkaline protease were leucine and histidine respectively.

• Resources Recycling
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• v.2 no.2
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• pp.1-8
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• 1993

This study was carried out in order to define the effective collectors and the opitimum conditions for the removal of iron ion in waste water by flotation method. The results obtained in this study are summarized as follows. Fe(II) and Fe(III) were removed effectively at pH7 and 6 respectively by using sodium lauryl sulfate, an anionic collector. The anionic collector, aeropromotor 845, removed both Fe(II) and Fe(III) effectively in pH ranges of from 5 to 9. The cationic collector, trimetyl dodecyl ammonium chloride, removed both Fe(II) and Fe(III) effectively in pH ranges from 10 to 11 and from 4 to 10, respectively. Therefore, Fe(II) and Fe(III) could be effectively removed by forming the iron hydroxide precipitates by simple pH adjustment of the solutions above precipitation point of ferrous and ferric ion by flotation method. Then, the effective pH regulator and collector were NaOH and $Na_2CO_3$,aeropromotor 845 and trimetyl dodecyl ammonium chloride, respectively.

• Journal of Microbiology and Biotechnology
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• v.1 no.2
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• pp.102-110
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• 1991

Alkalophilic Bacillus sp. YJ-451, which was isolated from soil at several area in Korea, produced a novel type of bacteriolytic enzyme (cell wall peptidoglycan hydrolase) extracellulary. The cell wall hydrolytic activity was identified as a clear zone on sodium dodecyl sulfate polyacrylamide gel electrophoresis containing 0.2% (w/v) cell wall of Bacillus sp. as substrate. This enzyme was successively purified 66 fold with 3.2% yield in culture broth by ammonium sulfate precipitation, CM-cellulose column chromatography, and gel filtration, followed by hydroxylapatite column chromatography. The molecular weight of the purified enzyme was estimated to be 27,000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis and gel filtration column chromatography. The optimum pH and temperature for the activity of the enzyme were pH 10.0 and $50^{\circ}C$, respectively. The enzyme was stable between pH 5.0 and 10.0 and up to $40^{\circ}C$. Among the microorganisms used in this experiment the enzyme was active against most of gram negative strains and the genus Bacillus such as B. megaterium, B. licheniformis, B. circulans, B. pumilus, B. macerans, B. polymyxa. The release of dinitrophenylglutamic acid but not reducing group from cell wall peptidoglycan digested by the enzyme suggested that the enzyme is a kind of peptidase which hydrolyzes the peptide bond at the amino group of D-glutamic acid in the peptidoglycan.