• Clean Technology
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• v.16 no.4
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• pp.239-244
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• 2010

The carboxylation of the fluorenyl epoxide with a spiro framework, 9,9'-Bis(4-oxiranylmethoxyphenyl) fluorine (2) was catalyzed by some onium salts such as quaternary ammonium and phosphonium salts to produce the corresponding five-membered cyclic carbonate (3) in an efficient and environmentally benign fashion. The coupling reactions depend greatly on the kind of the halide anions and alkyl chain length of the onium salts. While the reaction was sensitive to the reaction temperature, the reaction trends suggest that the catalytic efficiency of the quaternary ammonium halides may correlate strongly with the melting points of the halides. The reactions using a catalytic amount (2 mol %) of quaternary ammonium bromide with an n-butyl chain at 75.9 bar of $CO_2$ and 393 K give the highest yield of the cyclic carbonate (92%).

• Analytical Science and Technology
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• v.20 no.2
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• pp.109-114
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• 2007

In this study, soxhlet extraction and dissolution-precipitation method are used for separating analyte from polymer materials. In soxhlet extraction efficiency test, it has been found that the DCM, Toluene, THF, and mixtures Acetone/Hexane (1:4, v/v) gave good extraction efficiency, while the use of the ethyl ether, acetone/ethyl ether (1:4, v/v), acetone/hexane (1:1, v/v), DCM/hexane (1:1, v/v) resulted in significantly lower values. In case of dissolution-precipitation method, there is no considerable difference with used different dissolving solvent. The elution amount of multi layer silica and Florisil column were determined with hexane 250 mL and 70 mL of hexane, respectively. Range of PBDE in real waste plastics was N.D.~1,028 ppm.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.8
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• pp.542-548
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• 2014

Effects of bromide ($Br^-$) and iodide ($I^-$) concentrations, chlorine ($Cl_2$) doses, pH, temperature, ammonia nitrogen concentrations, reaction times and water characteristics on formation of iodinated trihalomethanes (I-THMs) during oxidation of iodide containing water with chlorine were investigated in this study. Results showed that the yields of I-THMs increased with the high bromide and iodide level during chlorination. The elevated pH significantly increased the yields of I-THMs during chlorination. The formation of I-THMs was higher at $20^{\circ}C$ than $4^{\circ}C$, $10^{\circ}C$ and $30^{\circ}C$. In chloramination study, addition of ammonium chloride ($NH_4Cl$) markedly increased the formation of I-THMs. Among the water samples collected from seven water sources including wastewater treatment plant (WWTP) effluent water (EfOM water), prepared humic containing water (HA water) and algal organic matter (AOM) containing water (AOM water), EfOM water generated the highest yields of I-THMs ($12.31{\mu}g/mg$ DOC), followed by HA water ($4.96{\mu}g/mg$ DOC), while AOM water produced the lowest yields of I-THMs ($0.99{\mu}g/mg$ DOC). $SUVA_{254}$ values of EfOM water, HA water and AOM water were $1.38L/mg{\cdot}m$, $4.96L/mg{\cdot}m$ and $0.97L/mg{\cdot}m$, respectively. The I-THMs yields had a low correlation with $SUVA_{254}$ values ($r^2$ = 0.002).

• Journal of Food Hygiene and Safety
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• v.20 no.3
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• pp.134-140
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• 2005

Boiling point and distillation range, melting range, and identification methods in general test method of Korea, Japan, Joint FAO/WHO Expert Committee of Food Additives (JECFA), and USA on chemical food additives were compared. Boiling point of propylene glycol was indicated as boiling point in Korea, distillate in Japan, distillation range in JECFA and USA, and its value was up to the standard. Distillation range of propionic acid was indicated as distillate in Korea and Japan, distillation range in JECFA and USA, and its value was up to the standard. There is no standard on distillation range of isopropyl alcohol in Japanese method. Test method of melting range on synthetic food additives was identical in all organizations, and there are 28 items to which this test method applies in Korean Food Additives Code. The standards on molting range of D-mannitol were different in various organizations, and in USA method there are no standards to which L-ascorbic acid, calciferol, and fumaric acid apply. Synthetic food additives performing the identification test were 251 items in Korean Food Additives Code, but there are no items to which manganese, glycerophosphate, bromate, thiosulfate, and bromide apply. Calcium benzoate was dissolved by heating in benzoate test and we could not identify the citrate in ferric citrate by method (2) of Korea and Japan. Identification test methods for ammonium, lactate, magnesium, copper, sulfate, phosphate, and zinc were identical in all organizations, and these could be identifed by current identification methods.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.2
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• pp.109-118
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• 2012

This study achieves results from 22 maternity breast milk samples in total to demonstrate exposure level and risk assessment of PBDEs in Seoul area. PBDEs were detected in all the breast milk samples of the present study, indicating that general population in these Seoul area are widely exposed to these chemicals. Residue levels of total PBDEs (sum PBDEs from tri- to hepta-BDE) ranged of 0.84~13.1 ng/g lipid with an arithmetic mean and median of 3.56 ng/g lipid and 2.6 ng/g lipid, respectively. Global comparison shows that the levels of total PBDEs were relatively similar to those of China, Taiwan and European country (Sweden), and somewhat higher than those in some Asian (Vietnam, Philippines, and Indonesia). In the present study, however, the levels of total PBDEs in human milk are still one to two orders of magnitude lower than those in North America. Contribution rate of each congener appeared to be predominant with BDE-47, followed by BDE-153, BDE-100, BDE-99, BDE-154 and BDE-183. The sum of BDE-47 and BDE-153 accounted for more than 65% of total PBDEs in most samples. From the result of the human risk assessment of infants for total PBDEs and BDE-47 by breast milk feeding, we could find out that the average daily doses and hazard index (95th percentile) were 16.5 ng/kg bw/day and $1.2{\times}10^{-1}$ each other when nursing for 6 months after infants born. However, it was concluded that the infant health hardly had adverse seriously effects under this research condition.

• Journal of Soil and Groundwater Environment
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• v.10 no.3
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• pp.38-45
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• 2005

The feasibility of stimulating in situ aerobic cometabolic activity of indigenous microorganisms was investigated in a trichloroethylene (TCE)-contaminated aquifer. A series of single-well natural drift tests (SWNDTs) was conducted by injecting site groundwater amended with a bromide tracer and combinations of toluene, oxygen, nitrate, ethylene and TCE into an existing monitoring well and by sampling the same well over time. Three field tests, Push-pull Transport Test, Drift Biostimulation Test, and Drift Surrogate Activity Test, were performed in sequence. Initial rate of toluene degradation was much faster than the rate of bromide dilution resulting from natural groundwater drift, indicating stimulation of indigenous toluene-oxidizing microorganisms. Transformation of ethylene, a surrogate probing overall activity of TCE transformation, was also observed, and its transformation results in the production of ethylene oxide, suggesting that some tolueneoxidizing microorganisms stimulated may express a orthomonooxygenase enzyme. Also in situ transformation of TCE was confirmed by greater retardation of TCE than bromide after the stimulation of toluene-oxidizing microorganisms. These results indicate that, in this environment, toluene and oxygen additions stimulated the growth and aerobic cometabolic activity of indigenous microorganisms expressing orthomonooxygenase enzymes. The simple, low-cost field test method presented in this study provides an effective method for conducting rapid field assessments and pilot testing of aerobic cometabolism, which has previously hindered application of this technology to groundwater remediation.

• Journal of Conservation Science
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• v.25 no.3
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• pp.283-291
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• 2009

Methyl Bromide that was used as fumigation gas turned out to be the substance of destroying the ozone layer. For that reason, at the Montreal Protocol in 1987 the use of methyl bromide was forbidden starting 2005 in the advanced country. Also according to the 2007 Bali Protocolly methyl bromide is expected to be forbidden and therefore the purpose of this study is to find out the effects of substitution fumigation gas (Ethylene Oxide+HFC 134a, Methyl Iodide, Cyanogen and Argon) on the metal(silver, copper and iron), wood(oregon pine), pigment(yellow, red, blue, white and black), textile(hemp, ramie, jute, silk1 and silk2 / indigo, safflower and cork) and paper. After the fumigation test, ethylene oxide+HFC 134a did not have changes in the weight and color of the material itself before and after the experiment. On exterior alteration, color change occurred partly on paper and metal. Also, in most materials color change extent was 0.5 to 1.5 on the average and showed scanty difference. The materials after the fumigation test with methyl iodide did not show weight changes after the test. However, color changes more than 1.0 was shown in most of the materials especially in dyed textile material. In blue pigment, the discoloration on the surface could be seen by naked eyes. Fumigation test with cyanogen gas did not show weight changes and discoloration is more than 1.5 before and after the test. The weight changes of test materials with the argon gas was decreased about 3 to 6%. It can be observed that discoloration on paper was generated. Color changes can be seen on jute dyed with safflower and cork for two weeks with argon gas and the extent was 6.3 and 6.0.

• Journal of the Korean Chemical Society
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• v.37 no.2
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• pp.228-236
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• 1993

The effect of ferric ion on the reaction of CH_3$MgI with benzylbromide was investigated by determining the product ratio between cross-coupling product, ethylbenzene (A) and homocoupling product, bibenzyl (B) in the presence of ferric ion. When CH_3$MgI prepared with pure magnesium was used, the ratio of A to B was 22 to 78 and with reagent grade magnesium, the ratio became 33 to 67 indicating that metallic impurities in magnesium affect the reaction mechanism to lead less homocoupling product, B. The ratio changes became significant when ferric chloride was added in the reaction mixture in catalytic amounts and the ratio of A to B reached to 80 to 20 at maximum. The reaction in the presence of ferric ion seems to follow mainly an ionic mechanism which involves iron-benzyl bromide ${\pi}$-complex formation. The complex formation is expected to be able to enhance ionic attack of CH_3$MgI on benzyl carbon to give more A.

• Fire Science and Engineering
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• v.33 no.6
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• pp.105-113
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• 2019

This study investigates the toxicity characteristics of two Non-Class 1E Cables (For security reasons, we refer to company A and company B) used in nuclear power plants according to the accelerated deterioration period. In accordance with NES 713 test equipment and standards, tests were carried out on non-aged cables and the cables subjected to 20- and 40-year-accelerated-deterioration; each of the cables was further classified into sheath and insulation. The test results showed that the toxicity indices of 20- and 40-year-accelerated-aged cables were higher than those for the non-aged cables, and 20-year-aged cables of both A and B companies showed the highest toxicity indices. This is attributed to the extensive emissions of carbon monoxide and halide gases such as hydrogen chloride and hydrogen bromide. Furthermore, to analyze the toxicity indices of sheath and insulation in detail, the US Department of Defense standard (MIL-DTL) was applied to determine whether the Toxicity index (T.I.) allowance was exceeded, and the results showed that the insulating materials emitted considerably more than the allowable limit.

• Journal of the Korean Chemical Society
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• v.26 no.6
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• pp.363-368
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• 1982

Ultraviolet spectrophotometric investigations were carried out on the systems of pyridine with iodine, iodine monobromide and iodine monochloride in carbon tetrachloride. The results reveal the formation of the one to one molecular complexes of the type, $C_5H_5N{\cdot}I_2$, $ C_5H_5$N{\cdot}IBr and $ C_5H_5N{\cdot}ICl$. Considering ${\lambda}_max$ according to the formation of charge transfer complexes has the blue shift with the increasing temperatures$25, 40, 60^{\circ}C$ the equilibrium constants K and molar absorptivities $\varepsilon$ of complexes were obtained. From these values, the thermodynamic parameters ${\Delta}H$, ${\Delta}G$ and ${\Delta}S$ for the formation of the above charge transfer complexes were obtained. These results indicate that the relative stabilities of iodine, iodine monobromide and iodine monochloride complexes with pyridine increase in the order, $ C_5H_5N{\cdot}I_2$ < $ C_5H_5N{\cdot}IBr$ <$ C_5H_5N{\cdot}ICl$. This may be a measure of relative acidity of halogen and interhalogen toward pyridine and can be explained by the polarizabilities of electron acceptors and the difference of electronegativities of halogen atoms.