• Analytical Science and Technology
• /
• v.7 no.3
• /
• pp.277-284
• /
• 1994

The spectrophotometric determination of rare earth elements with XO was investigated in the presence of cetylpyridium chloride(CPC), dodecyltrimethylammonium bromide(DTMAB), cetyltrimetylammonium bromide (CTMAB), Triton X-100 at pH 6.2. The complex between XO and rare earth elements in the presence of cationic surfactants was very stable and more sensitive than in the absence of surfactants. The largest absorbance increase was provided by CTMAB, which was therefore chosen for determination of rare earth elements. REE-XO-CTMAB complex has absorption maxima at 618nm and obeys the Beer's law in the range of 0~0.5 ppm. Molar absorptivity was $1.5{\times}10^5mol^{-1}cm^{-1}l$.

• The Korean Journal of Pharmacology
• /
• v.2 no.2
• /
• pp.47-53
• /
• 1966

The bacteriostatic action of trichlorophenoxy alkylene ammonium derivatives, 2(2,4,5-trichlorophenoxy) ethylene N-triethyl ammonium bromide; (2,4,5-TETB), 2(2,4,6-trichlorophenoxy) ethylene N-triethyl ammonium bromide; (2,4,6-TETB), 2,4,5-triphenoxy ethylene pyridinium bromide; (2,4,5-TEPB), and 2,4,6-trichlorophenoxy ethylene pyridinium bromide:(2,4,6-TEPB) were observed by Jackson and Finland's and Finland's and Pak's on Staphylococcus aureus, E. coli, Salmonella typhi, Shigella flexneri, and Bacillus subtilis, comparing with those of phenol and trichlorophenol. The following results were obtained. 1) Phenol is bacteriostatic in a concentration of $10^{-3}$ for all above species. 2) Trichlorophenol is bacteriostatic in concentration of $10^{-4}$ to $5{\times}10^{-5}$ for all above species(Table 7), 3) 2,4,5-TETB and 2,4,6-TETB are bacteriostatic in a concentration of $10^{-4}$ and $5{\times}10^{-5}$ for Staphylococcus aureus, Salmonella typhi, and Shigella flexneri, but do not for E. coli and Bacillus subtilis(Table 8 and 9). 4) 2,4,5-TEPB and 2,4,6-TEPB are bacteriostatic in a concentrationof $10^{-4}$ and $5{\times}10^{-5}$ only for Staphylococcus aureus among four species(Table 10 and 11).

• Analytical Science and Technology
• /
• v.8 no.2
• /
• pp.107-116
• /
• 1995

The critical micelle concentration(CMC) of CTAB was determined with changes in absorbance at 202nm band of 4-biphenyl acetate($BPA^-$). With $BPA^-$ as a probe, the effect of temperature on CMC of CTAB has been observed between $30^{\circ}C{\sim}70^{\circ}C$. In this range of temperature the values of CMC are $1.18{\times}10^{-4}{\sim}2.02{\times}10^{-4}M$. The free energy(${\Delta}G^{\circ}m$) and enthalpy(${\Delta}H^{\circ}m$)for the micellization of CTAB was negative and the entropy(${\Delta}S^{\circ}m$) was a large positive value. The micellization of CTAB is considered as a spontaneous process and to involve a phase transition. The orientational binding of 4-biphenyl acetate anion to the CTAB micelle interface has been studied with $300MHz\;H^1-NMR$ data. The change in chemical shift of proton in CTAB as well as those of the protons in $BPA^-$ have been investigated by increasing the mole fraction of the anion in the mixed solutions. The changes in chemical shift with increasing mole fraction of anion($BPA^-$) indicate the formation of mixed micelle between CTAB and $BPA^-$. The changes in chemical shifts of methylene protons in CTAB, demonstrate the penetration of $BPA^-$ into the palisade layer of the CTAB micelle.

• Journal of Korean Society of Water and Wastewater
• /
• v.29 no.5
• /
• pp.575-581
• /
• 2015

Although disinfection in drinking water treatment plants provides a safer water supply by inactivating pathogenic microorganisms, harmful disinfection by-products may be formed. In this study, the disinfectant, chlorine, was produced on-site from the electrolysis of salt (NaCl), and the by-products of the disinfection process, bromate and chlorate, were analyzed. The provisional guideline levels for bromate and chlorate in drinking water are $10{\mu}g/L$ and $700{\mu}g/L$, in Korea, respectively. Bromide salt was detected at concentrations ranging from 6.0 ~ 622 mg/kg. Bromate and chlorate were detected at concentrations ranging from non-detect (ND) ~ 45.3mg/L and 40.5 ~ 1,202 mg/L, respectively. When comparing the bromide concentration in the salt to the bromate concentration in the chlorine produced by salt electrolysis, the correlation of bromide to bromate concentration was 0.870 (active chlorine concentration from on-site production: 0.6-0.8%, n=40). The correlation of bromate concentration in the chlorine produced to that in the treated water was 0.866.

• Applied Chemistry for Engineering
• /
• v.10 no.3
• /
• pp.461-466
• /
• 1999

The humidity sensor containing ammonium salt was prepared from the copolymer of 2-methacryloxyethyl dimethyl 2-hydroxyethyl ammonium bromide (MDHAB)/MMA/DAEMA = 6/3/1. The humid membrane was fabricated on the gold/alumina electrode by dipping. The impedances were $298k{\Omega},\;11k{\Omega}$, and $2.3k{\Omega}$ at 40%RH, 70%RH and 90%RH, respectively, at $5^{\circ}C$ and the humidity-sensitive characteristics were suitable for low temperature humidity sensor. The temperature-dependent coefficient between $5^{\circ}C$ and $20^{\circ}C$ was found to be $-0.80%RH/^{\circ}C$ and the hysteresis falled in the ${\pm}2%RH$ range. The response time was found to be 38 sec for the relative humidity ranging from 34%RH to 88%RH at $20^{\circ}C$. The reliabilities such as temperature cycle, humidity cycle, high temperature and humidity resistance, electrical load stability, stability of long-term storage and water durability were measured and evaluated for the application as a humidity sensor.

• Applied Chemistry for Engineering
• /
• v.21 no.3
• /
• pp.337-342
• /
• 2010

The interaction of monochlorophenol isomers with the micellar system of TTAB (tetradecyltrimethylammonium bromide) was studied by the UV/Vis spectrophotometric method. The solubilization constants ($K_s$) of monochlorophenol isomers into this micellar system have been measured with the change of temperature. Various thermodynamic parameters (${\Delta}G^{\circ}_s$, ${\Delta}H^{\circ}_s$, and ${\Delta}S^{\circ}_s$) have been calculated and analyzed from the dependence of $K_s$ values on the temperature. The results show that the values of ${\Delta}G^{\circ}_s$ and ${\Delta}H^{\circ}_s$ are all negative but the values of ${\Delta}S^{\circ}_s$ are all positive for the solubilizations of all isomers within the measured temperature range. The effects of additives (n-butanol and NaCl) on the solubilization of monochlorophenol isomers by the same surfactant system have been also measured. There was a great change on the values of $K_s$ and CMC simultaneously with these additives. From these changes we can postulate the solubilization sites of each isomer in the micellar system of TTAB.

• Korean Journal of Food Science and Technology
• /
• v.35 no.5
• /
• pp.825-829
• /
• 2003

An electronic nose was applied to analyze the aroma patterns of powdered red ginseng that had been treated with different preservative methods, such as gamma radiation at 5kGy, commercial methyl bromide (MeBr) and phosphine fumigations. Aroma patterns of phosphine or MeBr, fumigated samples were well separated according to storage temperature and period. However, 5kGy-irradiated samples (stored for 1 and 2 months) were hardly discriminated by the different storage temperatures ($25^{\circ}C$ and $-10^{\circ}C$). After 5 months at $-10^{\circ}C$, non-treated and phosphine fumigated samples showed similar aroma patterns.

• Journal of the Korean Chemical Society
• /
• v.36 no.1
• /
• pp.28-32
• /
• 1992

The critical micelle concentration(CMC) values of Dodecylpyridinium bromide(DoPB) were determined by an electric conductivity method at 1${\sim}$2000 bars and $25^{\circ}C$. The CMC of DoPB increases with the addition of urea in the whole pressure region studied, and the CMC increases with an increase of the pressure in the low-pressure region, while in the high-pressure region the CMC decreases. The partial molar volume change $({\Delta}V^m_o)$ on micellization was also investigated in some urea aqueous solutions. The change $({\Delta}V^m_o)$ was reduced by the addition of urea. The results suggest that the "iceberg" structure of water around the hydrocarbon chain of the monomeric surfactant is effectively broken down by urea.

• Polymer(Korea)
• /
• v.31 no.3
• /
• pp.194-200
• /
• 2007

The resistive-type polymeric humidity sensors were prepared from the copolymers of [2- [(methacryloyloxy)ethyl] dimethyl] propylammonium bromide(MEPAB), [2- [(methacryloyloxy)ethyl]-2-hydroxyethyl]dimethylmonium bromide (MEHDAB), n-butyl methylacrylate(MBA), 2-hydroxyethyl methylacrylate(HEMA) and styrene. Four kinds of copolymers, ie, MEPAB/styrene/MEHDAB MEHDAB/BMA/HEMA, MEPAB/BMA/MEHDAB, and MEPAB/styrene/HEMA crosslinked with blocked-isocyanate on the Ag/Pd electrode/alumina substrate showed good durability at high humidities. The various electrical properties such as frequency dependency, temperature dependency, hysteresis, response time and water durability were examined. In the case of copolymer MEPAB/BMA/MEHDAB= 3/6/1, the resistance was varied from $2.9 M{\Omega}$ to $1.84k{\Omega}$ at $25^{\circ}C$ in the range of $30{\sim}90%RH$ and this copolymers showed a good linearity and low hysteresis.

• Journal of the Korean Chemical Society
• /
• v.55 no.4
• /
• pp.685-690
• /
• 2011

Novel acidic ionic liquids, 1-(${\omega}$-sulfonicacid)propyl-3-methylimidazolium bromide ([$HSO_3$pmim]Br)and 1-(${\omega}$-sulfonicacid)butyl-3-methylimidazolium bromide ([$HSO_3$bmim]Br), were prepared and used as brominating agents, catalysts and solvents in the synthesis of 1,7-dibromoheptane, respectively. 1,7-dibromoheptan with a yield of 95% was obtained at $100^{\circ}C$ for 2 h by simple phase separation. The acidic ionic liquid [$HSO_3$pmim]Br was recycled for 5 times and the yield of 1,7-dibromoheptane did not decrease remarkably, which indicates that catalysts still maintain good selectivity and activity after recycling. The structure of the acidic ionic liquid [$HSO_3$pmim]Br was characterized with IR, and it was found that [$HSO_3$pmim]Br had stronger acidity than other ionic liquid.