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Kinetic Analysis for Decomposition of 2,4-Dichlorophenol by Supercritical Water Oxidation
이창하,황경엽,이현철,Jung-Hyun In,Jong-Hwa Kim 한국화학공학회 2005 Korean Journal of Chemical Engineering Vol.22 No.6
2,4-Dichlorophenol (2,4-DCP), as a halogenated model pollutant, was decomposed by using supercritical water oxidation (SCWO) in a batch reactor made of Hastelloy C-276. SCWO experiments for 2,4-DCP decomposition were performed in the range of 380-420 oC, 230-280 bar and 0.074- 0.221 mol/L H2O2. The effect of oxidant concentration on decomposition rate and efficiency was significant near the critical temperature of 380 oC. However, the role of the oxidant concentration in the SCWO process decreased with an increase in temperature; also, excess oxidant played a key role in quite significantly decreasing the activation energy of 2,4-DCP oxidation. Variation of the reaction rate by the change of pressure was negligible even at a near critical temperature. The kinetic rate for the decomposition of 2,4-DCP in the SCWO process was well described by a simple first-order kinetic and global reaction rate model. From the SCWO experiments, the various intermediates identified with a GC/MS implied that the first reaction pathway for 2,4-DCP decomposition led to dimers such as dichlorophenoxyphenols, and the second led to single-ring and ringopening products.
Li Huang,Yan Zhou,Xiangquan Guo,Zuliang Chen 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.22 No.-
In this paper, the sorption of 2,4-DCP onto DK4 (modified with dioctadecyldimethylammoniumchloride(DDAC)) was 3–5 times more than when using Na-bentonite, while sorption of Pb(II) on DK4 was notdifferent from using Na-bentonite. Sorption isotherms for 2,4-DCP and Pb(II) were well described by theLangmuir isotherm (R2 > 0.99), while pseudo-second-order kinetic model provided good kinetic datafitting (R2 > 0.99). Furthermore, DK4 was characterized by SEM–EDS, XRD and FTIR, it is concluded thatthe co-sorption of 2,4-DCP and Pb(II) onto DK4 occurred through the partition mechanism for adsorbing2,4-DCP and the ion-exchange mechanism for the sorption of Pb(II).
UV/H<sub>2</sub>O<sub>2</sub>를 이용한 2,4-DCP의 산화에 NO<sub>3</sub><sup>-</sup> 이온이 미치는 영향
박재한,이지영,안윤희,문태훈,임성균,고광백,Park, Jae Han,Lee, Ji Yong,Ahn, Yoon Hee,Moon, Tae Hoon,Yim, Sung Kyun,Ko, Kwang Baik 한국물환경학회 2007 한국물환경학회지 Vol.23 No.3
The Advanced Oxidation Process (AOP) is being increasingly used to oxidize complex organic constituents in treated effluents from domestic wastewater treatment plants. Generally, ${NO_3}^--N$ concentrations ranges between 5 and 8 mg/L for biologically well-treated effluents. However, nitrate ions, ${NO_3}^-$, affects on oxidation as not only a well-known strong absorber of UV light below 250 nm of wavelength but also as an OH radical scavenger. The objective of this study was to evaluate the AOP systems for degradation of 2,4-DCP, and to delineate the effect of nitrate ions on UV oxidation of 2,4-DCP by conducting a bench-scale operation at various reaction times and initial concentrations of $H_2O_2$. The experimental results indicated that 2,4-DCP could be completely oxidized by $UV/H_2O_2$ process with an initial $H_2O_2$ concentration of 20 mg/L at a retention time of 1.0 min or longer. Nitrate ions did not show any adverse effect on 2,4-DCP oxidation at this high $H_2O_2$ concentration, and the practical initial $H_2O_2$ concentration and reaction time for the 80% oxidation turned out to be 5 mg/L and 1.0 min, respectively.
호기성 분해, 혐기성 분해 및 독성을 고려한 생분해도 지표 개발
유규선,신항식 대한상하수도학회 2010 상하수도학회지 Vol.24 No.5
More than 8 millions of chemical have been used for human activities and lots of chemicals can not be degraded by microbial activities in this world. To show the biodegradability of a chemical, biodegradability index (B.I.) is suggested using aerobic biodegradability by BOD5/COD, anaerobic biodegradability by methane potential (M.P.) and toxicity by the luminiscent bacteria. In this study, PVA (polyvinyl alcohol), HEC (hydroxy ethyl cellulose), 2,4,6-TCP (tri-chloro phenol) and 2,4-DCP (di-chloro phenol) are used for test chemicals. Though they show little toxicity, PAV and HEC have low B.I. because they are polymers having high molecular weight. That means that there are no bacteria that has enzyme to degrade polymer molecules. Also, anaerobic treatment is suggested better than aerobic treatment from B.I. 2,4,6-TCP and 2,4-DCP show high toxicity and have low B.I. Their low biodegradabilities seem to be originated from their toxicities. If B.I. is used in wastewater treatment, better treatment process can be suggested and finally it can lead our society to make more environment-friendly chemicals.
Ryu, K.,Hwang, S.Y.,Kim, K.H.,Kang, J.H.,Lee, E.K. Elsevier Science Publishers 2008 Journal of biotechnology Vol.133 No.1
One of the major problems of wild-type lignin peroxidase (LiP) is its inactivity at the presence of excess H<SUB>2</SUB>O<SUB>2</SUB> and high concentration of aromatic compounds. Little is known about the substrate-binding site of LiP, and functionality improvement of LiP was not actively tried by genetic engineering and directed evolution. In order to improve LiPs functionality, we performed directed evolution with a colorimetric screening method. Finally, three types of LiP mutants were screened. The catalytic efficiency of the variants toward 2,4-dichlorophenol (DCP) degradation activity and the stability against H<SUB>2</SUB>O<SUB>2</SUB> was increased over the wild type. The K<SUB>m</SUB> value of the variants toward H<SUB>2</SUB>O<SUB>2</SUB> was increased, but K<SUB>m</SUB> value toward 2,4-DCP degradation was reduced. Overall, The K<SUB>cat</SUB>/K<SUB>m</SUB> values of the mutants toward 2,4-DCP was increased ca. 4-fold, and that toward H<SUB>2</SUB>O<SUB>2</SUB> was increased ca. 89-fold. Amino acid sequence analysis indicated that the most of the mutations were located on the enzyme surface. We expect that these results coupled with recombining mutation can be successfully applied to the molecular evolution cycles for screening of LiPs and other oxidative enzymes with improved functionality and stability.
Isolation and Characterization of Soil Streptomyces Involved in 2,4-Dichlorophenol Oxidation
Kang, Min Jin,Kang, Ja KYoung,Kim, Eung Soo 한국미생물 · 생명공학회 1999 Journal of microbiology and biotechnology Vol.9 No.6
Over 50 morphologically distinctive soil Streptomyces were isolated from various locations in the Yongin area in Korea and visually screened for dye-decoloring activities on an agar plate. Two Streptomyces species (AD001 and ND002) showed strong dye-decoloring activities on the plate containing congo-red and new-fuchin dyes, respectively. Also, the liquid culture supernatants of these species showed 2,4-dicholophenol (DCP) oxidation activities only in the presence of hydrogen peroxide, a characteristic of Actinomycetes lignin-peroxidase (ALiP)-P3 isoform found in dye-degrading S. viridosporus T7A and S. badius 252. Based on their dye-decoloring capabilities and the 2,4-DCP oxidation kinetic data, it is suggested that these Streptomyces secrete not-yet-characterized extracelluar enzyme(s), whose activities are very similar to the ALiP-P3 enzyme.