• Korean Chemical Engineering Research
• /
• v.43 no.6
• /
• pp.745-750
• /
• 2005

Naphtha cracking bottoms(NCB) oil was reformed by varying the heat treatment temperature, treatment time, and nitrogen flow rate in preparation of precursor pitch for isotropic pitch-based carbon fibers and activated carbon fibers. The reformed pitches were investigated in the yield, softening point, elementary analysis, and molecular weight distribution, and then the precursors reformed were melt spun to certify the optimum reforming conditions. The optimum precursor pitch was prepared when the NCB oil was reformed at $380^{\circ}C$, 3 h and 1.25 vvm $N_2$, and it's the softening point was around $240^{\circ}C$. The reforming resulted in product yield of 21 wt％. The C/H mole ratio of the precursor pitch increased from 1.07 to 1.34, the aromaticity increased from 0.85 to 0.88. The insolubles in benzene and quinoline were 30.0 wt％ and 1.5 wt％, respectively. The spinning temperature was about $50^{\circ}C$ higher than the softening point. The molecular weights of the precursor components were distributed from 250 to 1250, and 80％ of them were in the range of 250 to 700.

• Environmental Analysis Health and Toxicology
• /
• v.10 no.1_2
• /
• pp.1-14
• /
• 1995

The purpose of this research is to assess the health risk of pollutants in drinking water and recommend the guidelines and management plans for maintaining good quality of drinking water. This study has been funded as a national project for three years from 1992 to 1995. This study(the second year, 1993-1994) was conducted to monitor 32 species of carcinogenic chemicals such as volatile organic compounds(VOCs), polynuclear aromatic hydrocarbons(PAHs), pesticides and heavy metals of drinking water at some area in six cities of Korea, and evaluate health risk due to these chemicals through four main steps of risk assessment in drinking water. In hazard identification, 32 species of carcinogenic chemicals were identified by the US EPA classification system. In the step of exposure assessment, sampling of raw, treated and tap water from the public water supply system had been conducted from 1993 to 1994, and 32 chemicals were analyzed. In dose-response assessment, cancer potencies, unit risk estimates and virtually safe doses of carcinogens were obtained by TOX-RISK (Version 3.1). In risk characterization of detected chemicals, health risk due to carcinogens such as vinyl chloride, carbon tetrachloride, dichloromethane, 1, 2-dichloromethane, chloroform, benzene and arsenic of tap water in several cities exceeded 10$^{-5}$ level. We suggest that non-regulated chemicals which exceed 10$^{-5}$ excess cancer risk level, such as vinyl chloride, carbon tetrachloride and 1, 2-dichloroethane, should be monitored periodically and be regulated by the Drinking Water Management Act, and database for exposure parameter of our own situation should be established.

• Korean Journal of Environmental Agriculture
• /
• v.10 no.2
• /
• pp.149-157
• /
• 1991

In order to elucidate the possible change in the non-extractable bound residue of TCAB(3,3' 4,4' - tetrachloroazobenzene) in soil as a function of aging period, uniformly ring-labelled $^{14}C-TCAB$ was treated to soil(organic matter : 1.8%), and aged for 3, 6, 9, 12 and 15 months at $21{\pm}1^{\circ}C$, respectively. $^{14}CO_2$ evolution and volatilization loss during the aging were negligible. The amounts of non-extractable bound residue of TCAB increased gradually from 7.55% in 3-month aging to 19.32% in 15-month aging. Partition data suggested no formation of polar groups in the chemical structure of TCAB. Most of $^{14}C-radioactivity$ of bound residues was present in humin in the range of 50.52 to 58.93%. The fact that the number of microorganisms in soil decreased relative to the control suggested no chance of their involvement in the formation of non-extractable bound residues. Accordingly, the increase in the non-extractable bound residue of TCAB in soil with aging period is believed to be due to the transformation of the trans isomer to the cis one which is more polar and more adsorptive than the former.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2000.11a
• /
• pp.207-208
• /
• 2000

Since trichloroethylene (TCE), dichloroethylene (DCE), and vinyl chloride (VC) arise from anaerobic degradation of tetrachloroethylene (PCE) and TCE, there is interest in creating aerobic remediation systems that avoid the highly toxic VC and cis-DCE which predonominate in anaerobic degradation. However, it seemed TCE could not be degraded aerobically without an inducing compound (which also competitively inhibits TCE degradation). It has been shown that TCE induces expression of both the toluene dioxygenase of p. putida F1 as well as toluene-p-monooxygenase of P.mendocina KRI. We investigated here the ability of PCE, TCE, and chlorinated phenols to induce toluene-o-xylene monooxygenase (ToMO) from P.stutzeri OX1. ToMO has a relaxed regio-specificity since it hydroxylates toluene in the ortho, meta, and para positions; it also has a broad substrate range as it oxidizes o-xylene, m-xylene, p-xylene, toluene, benzene, ethylbenzene, styrene, and naphthalene; chlorinated compounds including TCE, 1, 1-DCE, cis-DCE, trans-DCE, VC, and chloroform : as well as mixtures of chlorinated aliphatics (Pseudomonas 1999 Maui Meeting). ToMO is a multicomponent enzyme with greatest similarity to the aromatic monooxygenases of Burkholderia pickettii PKO1 and P.mendocina KR1. Using P.sturzeri OX1, it was found that PCE induces P.mendocina KR1 Using P.situtzeri OX1, it was found that PCE induces ToMO activity measured as naphthalene oxygenase activity 2.5-fold, TCE induces 2.3-fold, and toluene induces 3.0 fold. With the mutant P.stutzeri M1 which does not express ToMO, it was also found there was no naphthalene oxygenate activity induced by PCE and TCE; hence, PCE and TCE induce the tow path. Using P.putida PaW340(pPP4062, pFP3028) which has the tow promoter fused to the reporter catechol-2, 3-dioxygenase and the regulator gene touR, it was determined that the tow promoter was induced 5.7-, 7.1-, and 5.2-fold for 2-, 3-, 4-chlorophenol, respectively (cf. 8.9-fold induction with o-cresol) : however, TCE and PCE did not directly induce the tou path. Gas chromatography and chloride ion analysis also showed that TCE induced ToMO expression in P.stutzeri OX1 and was degraded and mineralized. This is the first report of significant PCE induction of any enzyme as well as the first report of chlorinated compound induction of the tou operon. The results indicate TCE and chlorinated phenols can be degraded by P.stutzeri OX1 without a separate inducer of the tou pathway and without competitive inhibition.

• Korean Journal of Pharmacognosy
• /
• v.9 no.3
• /
• pp.149-156
• /
• 1978

The result of the study about the cultivation, the constituents, the sweetenity, and the development of preparations of Stevia and Hydrangea are as follows: 1. Hydrangea thrived at $200{\sim}1,400m$ above the sea-level, and the good ones were brought up at $600{\sim}1,200m$. 2. The good ones which belonged to the genera of Hydrangea were produced in the damp, dark and cold place. 3. The growth and cultivated yield of Stevia was not significantly influenced by the acidity of the soil. 4. The best season was May and June for propagation of Stevia by cutting method. 5. The growth rate of Stevia and Hydrangea was really good in the sandy fertile soil, but in the mucotic soil it was not suitable. 6. The extraction and separation of phyllodulcin by solvent had many difficulties, because it was very soluble in water, ethanol, ether, petroleum ether, acetone and benzene, etc. 7. The solubility of stevioside on the solvent was as follows: It was very soluble in water and methanol, slightly soluble in ethanol and acetone, and insoluble in ether, petroleum ether and chloroform. 8. The alkaloid reaction by Mayer reagent in Hydrangea extract was positive. 9. The ashification rate of Stevia was 8.66% to 8.72% and that of Hydrangea 17.02% to 17.04%. 10. The tannin of Stevia leaf was 7.80% to 7.88% and its of Hydrangea decreased 9.46% to 6.08% by fermentation. 11. The percent rates in minimum concentration-occurring sweetness in sugar, glycyrrhiza methanol extract, Hydrangea water extract, Stevia leaf water extract, decoction of Stevia's leaf, decoction of Stevia's stem were as follows: 1.2, 0.1, 0.1, 0.2, 0.4, 0.01, 0.1, 0.6. and sweetenity ratios of those were 1, 12, 12, 6, 3, 64, 12, 2, 12. It was very meaningful to develop preparations of stevia as stevioside, micronized powder, water extract, methanol extract and compound teas and in Hydrangea, water extract, methanol extract, single tea, and compound teas were less meaningful. 13. The genera of Hydrangea which is natural species in Korea was positive in phyllodulcin-identification test, but it was not available to make the sweet tea because of having a little content.

• Applied Chemistry for Engineering
• /
• v.10 no.3
• /
• pp.349-353
• /
• 1999

A study was carried out to see the effects of phenol on the biological degradation of a wastewater containing 2,4-dichlorophenol and 2,4-dinitrophenol and the biodegradation kinetic coefficients of Eckenfelder's modified model for the activated sludge process. The system containing base mix (BM) which was formulated with essential energy sources and nutrients was run down and washed out when 2,4-dichlorophenol and 2,4-dinitrophenol was introduced into the base mix unit without acclimation to phenol. Whereas for the system acclimated to phenol, the treatment efficiency was 91.9% in terms of $BOD_5$ and treatability for each chemical of phenol, 2,4-dichlorophenol, and 2,4-dinitrophenol was 99.8%, 43.3% and 62.5% based on concentration, respectively. Additional BM was added into the combined unit containing phenol, 2,4-dichlorophenol, 2,4-dinitrophenol so that the better treatment efficiency was achieved for each compound. The biokinetic coefficient of Eckenfelder's modified model without phenol acclimation was not estimated because the system did not reach the steady state. Thc coefficient for the phenol acclimation was 12.44 /day, however it was changed as 46.91 /day in addition of both of phenol acclimation and 47 mg/l of BM. The results presented above could be useful for the process design and further study in the field of biodegradation of benzene derivatives.

• Applied Chemistry for Engineering
• /
• v.10 no.3
• /
• pp.427-431
• /
• 1999

Copolyester resins for the coil coating process of aluminium and steel strip were synthesized and their thermal properties, molecular weight and solvent solution characteristics were examined. Copolyesters were obtained by two step reactions. The first step was to prepare bishydroxyethyl terephthalate (BHET), bishydroxyneopentyl terephthalate (BHNPT), bishydroxyethyl isophthalate (BHEI), bishydroxyneopentyl sebacate (BHNPS), bishydroxyneopentyl adipicate (BHNPA) and bishydroxyethyl adipicate (BHEA) oligomers by esterification reactions. The second step was the polycondensation reaction utilizing those oligomers to obtain relatively high molecular weight copolyesters (Mw = 30,000~59,000 g/mol) as measured by GPC. These copolyesters were amorphous polymers as shown by DSC without $T_m$ peaks probably due to the kink structure introduced by BHET oligomer and relatively large free volume by bulky BHNPT and BHNPS oligomers. The copolyester samples with half of BHET oligomer substituted by BHNPT while keeping BHEI (0.3 mole) and BHNPS (0.1 mole) ratio constant showed glass transition temperature above $40^{\circ}C$ and good solubility in toluene both at low ($-5^{\circ}C$) temperature and room temperature.

• Korean Journal of Food Science and Technology
• /
• v.13 no.2
• /
• pp.107-113
• /
• 1981

Free sugars were isolated from ginseng root and its products and analyzed by using high performance liquid chromatogrphy. To isolate free sugars from aqueous sample solution fat-soluble components, crude saponin and protein were removed from the solution by extracting with benzene, water-saturated butanol and 80% ethanol, respectively. Free sugars found from both ginseng root and its products were fructose, glucose, sucrose and maltose, and the only sugar detected from red ginseng root and its products was rhamnose. Major sugar detected from fresh ginseng and white ginseng roots was sucrose, while sucrose and maltose were major sugars of red ginseng root.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2009.06a
• /
• pp.84-85
• /
• 2009

New approaches for detecting, preventing and remedying environmental damage are important for protection of the environment. Procedures must be developed and implemented to reduce the amount of waste produced in chemical processes, to detect the presence and/or concentration of contaminants and decontaminate fouled environments. Contamination can be classified into three general types: airborne, surface and structural. The most dangerous type is airborne contamination, because of the opportunity for inhalation and ingestion. The second most dangerous type is surface contamination. Surface contamination can be transferred to workers by casual contact and if disturbed can easily be made airborne. The decontamination of the surface in the nuclear facilities has been widely studied with particular emphasis on small and large surfaces. The amount of wastes being produced during decommissioning of nuclear facilities is much higher than the total wastes cumulated during operation. And, the process of decommissioning has a strong possibility of personal's exposure and emission to environment of the radioactive contaminants, requiring through monitoring and estimation of radiation and radioactivity. So, it is important to monitor the radioactive contamination level of the nuclear facilities for the determination of the decontamination method, the establishment of the decommissioning planning, and the worker's safety. But it is very difficult to measure the surface contamination of the floor and wall in the highly contaminated facilities. In this study, the poly(styrene-ethyl acrylate) [poly(St-EA)] core-shell composite polymer for measurement of the radioactive contamination was synthesized by the method of emulsion polymerization. The morphology of the poly(St-EA) composite emulsion particle was core-shell structure, with polystyrene (PS)as the core and poly(ethyl acrylate) (PEA) as the shell. Core-shell polymers of styrene (St)/ethyl acrylate (EA) pair were prepared by sequential emulsion polymerization in the presence of sodium dodecyl sulfate (SOS) as an emulsifier using ammonium persulfate (APS) as an initiator. The polymer was made by impregnating organic scintillators, 2,5-diphenyloxazole (PPO) and 1,4-bis[5-phenyl-2-oxazol]benzene (POPOP). Related tests and analysis confirmed the success in synthesis of composite polymer. The products are characterized by IT-IR spectroscopy, TGA that were used, respectively, to show the structure, the thermal stability of the prepared polymer. Two-phase particles with a core-shell structure were obtained in experiments where the estimated glass transition temperature and the morphologies of emulsion particles. Radiation pollution level the detection about under using examined the beta rays. The morphology of the poly(St-EA) composite polymer synthesized by the method of emulsion polymerization was a core-shell structure, as shown in Fig. 1. Core-shell materials consist of a core structural domain covered by a shell domain. Clearly, the entire surface of PS core was covered by PEA. The inner region was a PS core and the outer region was a PEA shell. The particle size distribution showed similar in the range 350-360 nm.

• Applied Biological Chemistry
• /
• v.31 no.3
• /
• pp.234-240
• /
• 1988

Some chloroacetamide derivatives were synthesized from 2,6-dialkyl, aniline 4-chloroaniline, or 3,4-dichloroaniline with alkyl 2-bromopropionate and chloroacetyl chloride and identified by elemental analyses, NMR, and GC/MS spectra as N-(1'-methoxycarbonylethyl)-N-chloroacetyl-2,6-dimethylaniline(ACRI-S-8609), etc. These compounds synthesized were subjected to the test for pre-emergence herbicidal effecs on some grass weeds(Digitaria adscendens, Setaria viridis, Echinochloa crus-galli) and broad leaf weeds(Portulaca oleracea, Amaranthus lividus, Chenopodium album) in pots applied as wettable powder formulations. It was found that N-(1'-ethoxycarbonylethyl)-N-chloroacetyl-2,6-dimethylaniline(ACRI-S-8701) has the highest herbicidal effect on grass weeds, which corresponds to a 95% control effect at an application of 200g a.i/10a. Whereas, some chloroacetamide derivatives derived from 4-chloroaniline or 3,4-dichloroaniline had very weak herbicidal effects on grass and broad leaf weeds.