• Journal of Korean Society of Environmental Engineers
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• v.27 no.3
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• pp.273-279
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• 2005

The degradation of o-chlorophenol(o-CP) in the presence of NaOH and the byproducts formed were investigated in a supercritical water(SCW) destruction process. The conversion of o-CP in the absence of NaOH was less than 20%, however it showed 100% conversion in the presence of NaOH(mole ratio[NaOH]/[o-CP] over than 2) with a residence time of less than 1 second. The formation of PAHs and the phenolic compounds formed were decreased in the presence of NaOH. The results revealed that the formation of byproducts during the destruction of o-CP in SCW was effected by the addition of NaOH. Phenol, cresols, chlorinated phenols, PAHs, p,p'-dihydroxybiphenyl and oxygenated polyaromatic compounds such as 1-indanone, dibenzofuran and dibenzo-p-dioxin were detected in both conditions(presence and absence of NaOH). At the same time, in the presence of NaOH, 2-ethylphenol, o-hydroxyacetophenone, hydroquinone, 4-allylphenol, 3-phenoxyphenol and 4,4'-oxybisphenol were also detected. The observed results suggest that the destruction of o-CP in SCW with NaOH occurs through a number of complicated reaction pathways. Dibenzofuran and dibenzo-p-dioxin were also detected during destruction of o-CP by SCW. The above observation suggests that there may be a common relationship between the thermal incineration process and SCW decomposition process.

• Applied Chemistry for Engineering
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• v.23 no.4
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• pp.405-408
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• 2012

$TiO_2$ particles with various shapes were synthesized by using a modified sol-gel method with binary ionic liquids. The structural properties of the particles were significantly affected by the composition of ionic liquids. This is mainly attributed to the interaction between the organic solvent and ionic liquid at the interface leading to the formation of particle structure. The photocatalytic activity of the prepared samples was also examined for the degradation of 4-chlorophenol. Among the particles, $TiO_2$ prepared with 1-octyl-3-methylimidazolium tetrafluoroborate and 1-octyl-3-methylimidazolium tetrafluoroborate showed the best photocatalytic performance.

• Applied Biological Chemistry
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• v.22 no.4
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• pp.198-209
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• 1979

L-Tyrosine, 2-chloro-L-tyrosine, 2-bromo-L-tyrosine, and 2-iodo-L-tyrosine were synthesized by ${\beta}-tyrosinase$ obtained from cells of Escherichia intermedia A-21, through the reversal of the ${\alpha},{\beta}-elimination$ reaction, and their molecular structures were analyzed by element analysis, NMR spectroscopy, mass spectrometry and IR spectroscopy. Rates of synthesis and hydrolysis of halogenated tyrosines by ${\beta}-tyrosinase$, inhibition of the enzyme activity by halogenated phenols, and effects of addition of m-bromophenol on the synthesis of 2-bromotyrosine were determined. The results obtained were as follows: 1) In the synthesis of halogenated tyrosines, the yield of 2-chlorotyrosine from m-chlorophenol were approximately 15 per cent, that of 2-bromotyrosine from m-bromophenol 13.8 per cent, and that of 2-iodotyrosine from m-iodophenol 9.8 per cent. 2) Rate of synthesis of halogenated tyrosines by ${\beta}-tyrosinase$ was slower than that of tyrosine and the rates were decreased in the order of chlorine, bromine and iodine, that is, by increasing the atomic radius. Relative rate of 2-chlorotyrosine synthesis was determined to be 28.2, that of 2-bromotyrosine to be 8.13, and that of 2-iodotyrosine to be 0.98, respectively, against 100 of tyrosine. However 3-iodotyrosine was not synthesized by the enzyme. 3) The relative rate of 2-chlorotyrosine hydrolysis by ${\beta}-tyrosinase$ was 70.7, that of 2-bromotyrosine was 39.0, and that of 2-iodotyrosine was 12.6 against 100 of tyrosine, respectively. The rate of hydrolysis appeared to be decreased in the order of chlorine, bromine and iodine, that is, by increasing the atomic radius or by decreasing the electronegativity. But 3-iodotyrosine was not hydrolyzed by the enzyme. 4) The activity of ${\beta}-tyrosinase$ was inhibited by phenol markedly. Of the halogenated phenols, o-, or m-chlorophenol and o-bromophenol gave marked inhibition on the enzyme action, however inhibition by iodophenol was not strong. Plotting by Lineweaver-Burk method, a mixed-type inhibition by m-chlorophenol was observed and its Ki value was found to be $5.46{\times}10^{-4}M$. 5) During the synthesizing reaction of 2-bromotyrosine by the enzyme, sequential addition of substrate which was m-bromophenol with time intervals and in a small amount resulted in better yield of the product. 6) The halogenated tyrosines which were produced by ${\beta}-tyrosinase$ from pyruvate, ammonia and m-halogenated phenols were analysed to determine their molecular structures by element analysis, NMR spectroscopy, mass spectrometry, and IR spectroscopy. The result indicated that they were 2-chloro-L-tyrosine, 2-bromo-L-tyrosine, and 2-iodo-L-tyrosine, respectively.

• Microbiology and Biotechnology Letters
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• v.30 no.3
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• pp.287-292
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• 2002

Lignin-peroxidase (LiP) has been considered as one of the most important industrial enzymes for biodegradation of various recalcitrant toxic compounds such as chlorinated aromatic hydrocarbons and azo-dyes. Recently, several soil actinomycetes have been reported to secrete a functionally-similar lignin-peroxidase called actinomycetes lig-nin-peroxidase (ALiP). In this manuscript, we isolated over 100 morphologically distinct actinomycetes from the contaminated soils around 10 different gas stations located nearby the Kyung-An river. Among these actinomycetes screened based on the congo-red dye-decolorization activities, one newly-isolated actinomycetes named SMA-2 showed the most significant dye-decoloring activity on the congo-red plate as well as a significant ALiP activity in a yeast-extract-malt-extract liquid media supplemented with starch. The optimum SMA-2 culture condition fur ALiP production was determined and the kinetic parameters fur the SMA-2 AkIP activity were characterized. The optimally-cultured SMA-2 also exhibited the oxidation activities toward various recalcitrant aromatic compounds including phenol, 2- chlorophenol, 4- chlorophenol, 2,4- dichlorophenol ,2,6- dichlorophenol, and 2,4, f-trichlorophe - not, suggesting a potential application of SMA-2 for contaminated soil bioremediation.

• Applied Biological Chemistry
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• v.35 no.4
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• pp.242-247
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• 1992

Twenty strains of pentachlorophnol (PCP) resistant bacteria were isolated from activated sludge of the sewage treatment plant of Jung Lang Chun, Seoul. The predominant strains were Bacillus spp. including B. sphaericus and E. schlegelii. The other strains were identified as Corynebacterium spp., Staphylococcus aureus, Arthrobacter spp. and Aeromonas spp. The resistant strains could be grouped into two categories; PCP-degrading and PCP-adsorbing/absorbing ones. PCP-degrading strains degraded $75{\sim}90%$ of PCP in the medium containing 100 ppm PCP during the first 24 hours of growth. At the initial period the PCP-adsorbing/absorbing strains removed PCP from the medium but started to release PCP after 24 or 72 hours of growth. PCP degradation products from the culture broth of PCP-degrading strains were identified by comparing their $R_f$ values with those of the reference compounds. 2-chlorophenol and 2.4-dichlorophenol were presumed to be the intermediate products of PCP degradation.

• Journal of Microbiology
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• v.44 no.1
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• pp.23-28
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• 2006

We investigated the effects of halogenated aromatic compounds (HACs) including naturally occurring ones (L-thyroxine, 3-chloro-L-tyrosine, 5-chloroindole, 2-chlorophenol, 4-chlorophenol and chlorobenzene) on polychlorinated biphenyl (PCB) dechlorination in sediment cultures. A PCB-dechlorinating enrichment culture of sediment microorganisms from the St. Lawrence River was used as an initial inoculum. When the culture was inoculated into Aroclor 1248 sediments amended with each of the six HACs, the extent of dechlorination was not enhanced by amendment with HACs. The dechlorination patterns in the HAC-amended sediments were nearly identical to that of the HAC-free sediments except the 3-chloro-L-tyrosine-amended ones where no dechlorination activity was observed. When these sediment cultures were transferred into fresh sediments with the same HACs, the dechlorination specificities remained the same as those of the initial inoculations. Thus, in the present study, the substrate range of the highly selected enrichment culture could not be broadened by the HACs. It appears that HACs affect PCB dechlorination mainly through population selection rather than enzyme induction of single population.

• Journal of Environmental Science International
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• v.13 no.6
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• pp.551-560
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• 2004

The feasibility and efficiency of the hydrogen peroxide produced by an electrolysis cell reactor was investigated, From regulating voltages for the given reaction time, the concentration of the hydrogen peroxide was gradually increased with increasing voltages. Optimal voltage range was found to be 10～15 V. The concentration of hydrogen peroxide was much higher with oxygen gas than without oxygen gas in the cathodic chamber. But there was a little difference in the generating rate of hydrogen peroxide regardless of the presence of nitrogen gas. Under given conditions, the maximum value of ICE(Instantaneous Current Efficiency) was about 38%, and then current density was 74 $mA/\textrm{cm}^2.$ The specific energy consumption was $0.694[kWh/kg-H_2O_2].$ Since Esp (Specific Energy Consumption)was very little value, It did not demand high energy in this system. Using the hydrogen peroxide gained in the experiment, Fenton's reaction was conducted and the removal of nitrobenzene, 3-chlorophenol and dye wastewater was studied. This results were very similar to the Fenton's reaction by using commercial hydrogen peroxide.

• Journal of Soil and Groundwater Environment
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• v.11 no.3
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• pp.59-65
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• 2006

Reductive dechlorination of chlorophenols by nickel coated iron was investigated to understand the feasibility of using Ni/Fe for the in situ remediation of contaminated groundwater. Zero valent iron (ZVI) was amended with Ni(II) ions to form bimetal (Ni/Fe). Dechlorination of 4-chlorophenol and formation of intermediates was studied using Ni/Fe. Effects of initial contaminant concentration, bimetal loading, presence of humic acid, and solution chemistry were also evaluated. Experimental results showed that Ni/Fe bimetal was so effective that more than 95% of 4-CP degradation was achieved within 240 minutes. Pseudo first-order rate constant for the dechlorination reaction was well correlated with bimetal loading. Humic acid competed for the reactive sites on the nickel coated iron with chlorophenols, lowering the dechlorination efficiency. No significant changes in solution pH were observed in the dechlorination of chlorophenols with Ni/Fe in the absence of buffer, indicating that reactivity of bimetal (Ni/Fe) could be prolonged. Phenol was found as a dechlorination intermediate of the conversion of 4-chlorophenol compound by Ni/Fe.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.3009-3016
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• 2012

This study evaluated the use of iron-impregnated SBA-15 (Fe/SBA-15) as a catalyst for the oxidative degradation of persistent phenol analogues, such as 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2-nitrophenol (2-NP), 4-nitrophenol (4-NP) and 2,4,6-trichlorophenol (2,4,6-TCP) in water. The oxidation reactions were carried out with reaction time, concentration of the phenols, amount of the catalysts, reaction temperature, pH of the reaction mixture as the process variables with or without using hydrogen peroxide as the oxidizing agent. The conversion achieved with Fe/SBA-15 at 353 K for 2-CP, 4-CP, 2-NP, 4-NP, 2,4,6-TCP was 80.2, 71.2, 53.1, 62.8, 77.3% in 5h with a reactant to $H_2O_2$ mole ratio of 1:1, and 85.7, 65.8, 61.9, 63.7, 78.1% in the absence of $H_2O_2$, respectively. The reactions followed pseudo first order kinetics. The leachability study indicated that the catalyst released very little iron into water and therefore, the possibility of secondary pollution is negligible.

• Journal of the Korean Electrochemical Society
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• v.7 no.2
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• pp.83-88
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• 2004

[ $DeniLite^{TM}$ ] laccase immobilized Pt electrode was used for amperometric detection of some catechol derivatives and o-aminophenol (OAP) derivative by means of substrate recycling. In case of catechol derivatives, the obtained sensitivities are 85, 79 and $57 nA/{\mu}M$ with linear ranges of $0.6\~30,\;0.6\~30\;and\; 1\~25 {\mu}M$ and detection limits (S/N=3) of 0.2, 0.2 and $0.3{\mu}M$ for 3,4-dihydroxycinnaminic acid (3,4-DHCA), 3,4-dihydroxybenzoic acid (3,4-DHBA) and 3,4-dihydroxyphenylacetic acid (3,4-DHPAA), respectively. In case of OAP derivative, the obtained sensitivity is $237 nA/{\mu}M$ with linear range of $0.2\~15{\mu}M$ and detection limit of 70 nM for 2-amino-4-chlorophenol (2-A-4-CP). The response time $(t_{90\%})$ is about 2 seconds for each substrate and the long-term stability is around 40-50days for catechol derivatives and 30 days for 2-A-4-CP with retaining $80\%$ of initial activity. The optimal pHs of the sensor for these substrates are in the range of 4.5-5.0, which indicates that stability of the enzymatically oxidized product plays a very important role in substrate recycling. The different sensitivity of the sensor for each substrate can be explained by the electronic effect of the sugstituent on the enzymatically oxidized form.