• Journal of the Korean Applied Science and Technology
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• v.34 no.2
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• pp.349-356
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• 2017

OH radical generation is one of the common method to evaluate photocatalytic activity. In many of previous studies, only the UV(Ultraviolet) light was applied to test photocatalytic ability of $TiO_2$ nanotubes by studying probe compound(4-Chlorobenzoic acid) concentration change in solution. Also, $TiO_2$ nanotubes were found to show some electrochemical characteristics when the flow of electric current was applied. In this study, the flow of electric current and UV light were applied at the same time to determine whether electrochemical characteristics of $TiO_2$ nanotube plate can give synergetic effect on the photocatalytic activity. $TiO_2$ nanotube was grown on Ti by anodic oxidation to create $TiO_2$ nanotube plate which can be used as a photocatalyst and a electrode that can undergo AOP(Advanced Oxidation Process) for water treatment. Probe compound solution was prepared using 4-chlorobenzoic acid and $H_2O$ as a solvent. NaCl was added to give conductivity to work as electrolyte. As a result, enough level of electric current flow was found to give synergetic photocatalytic effect which can be used for efficient AOP water treatment method.

• Korean Journal of Microbiology
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• v.32 no.2
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• pp.126-131
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• 1994

The pchABCD genes in Pseudomonas sp. DJ-12 speciyin degradation o 4-chlorobiphenyl(4CB) were cloned in Eschericia coli. The cloned cells of E. coli CU1 and CU101 showed to produce 2,3-dihydroxybiphenyl (2,3-DHBP) from 4-chlorobiphenyl by dechlorination, as Pseudomonas so. DJ-12 produced 2,3-DHBP from both biphenyl and 4CB. In particular, E. coli CU101 transformed with the recombinant plasmid of pCU101 revealed dechlorination activity to produce 2,3-DHBP from 4CB without production of 4-chlorobenzoic acid. Therefore, the pcbAB genes (2.2 kb in size) cloned from the chromosome of Pseudomonas sp. DJ-12 were found to have dechlorination activity on 4CB to produce 2,3-DHNP.

• Journal of Microbiology
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• v.35 no.1
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• pp.53-60
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• 1997

Pseudomonas sp. P20 and Pseudomonas sp. DJ-12 isolated from the polluted environment are capable of degrading biphenyl and 4-chlorobiphenyl (4CB) to produce benzoic acid and 4-chlorobenzoic acid (4CBA) respectively, by pcbABCD-encoded enzymes. 4CBA can be further degraded by Pseudomonas sp. DJ-12, but not by Pseudomonas sp P20. However, the meta-cleavage activities of 2, 3-dihydroxybiphenyl (2, 3-DHBP) and 4-chloro-2, 3-DHBP dioxygenases (2, 3-DHBD) encoded by pcbC in Pseudomonas sp. P20 were stronger than Pseudomonas sp. DJ-12. In this study, the pcbC gene encoding 2, 3-DHBD was cloned from the genomic DNA of Pseudomonas sp. P20 by using pKT230. A hybrid plasmid pKK1 was constructed and E. coli KK1 transformant was selected by transforming the pKK1 hybrid plasmid carrying pcbC into E. coli XL1-Blue. By transferring the pKK1 plasmide of E. coli KK1 into Pseudomonas sp. DJ-12 by conjugation, a recombinant strain Pseudomonas sp. P20, Pseudomonas sp. DJ-12, and the recombinant cell assay methods. Pseudomonas sp. DJ12-C readily degraded 4CB and 2, 3-DHBP to produce 2-hydroxy-6-oxo-6-phenylhexa-2, 4-dienoic acid (HOPDA), and the resulting 4CBA and benzoic acid were continuously catabolized. Pseudomonas sp. DJ12-C degraded 1 mM 4CB completely after incubation for 20 h, but Pseudomonas sp. P20 and Pseudomonas sp. DJ-12 showed only 90% and Pseudomonas sp. DJ-12 had, but its degradation activity to 2, 3-DHBP, 3-methylcatechol, and catechol was improved.

• Microbiology and Biotechnology Letters
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• v.22 no.4
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• pp.353-359
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• 1994

Pseudomonas sp. P20 was a bacterial isolate which has the ability to degrade 4-chlorobi- phenyl(4CB) to 4-chlorobenzoic acid via the process of meta-cleavage. The recombinant plasmid pCK1 was constructed by insetting the 14-kb EcoRI fragment of the chromosomal DNA containing the 4CB-degrading genes into the vector pBluescript SK(+). Subsequently, E. coli XL1-Blue was transformed with the hybrid plasmid producing the recombinant E. coli CK1. The recombinant cells degraded 4CB and 2,3-dihydroxybiphenyl(2,3-DHBP) by the pcbAB and pcbCD gene products, respectively. The pcbC gene was expressed most abundantly at the late exponential phase in E. coli CK1 as well as in Pseudomonas sp. P20, and the level of the pcbC gene product, 2,3-DHBP dioxygenase, expressed in E. coli CK1 was about two-times higher than in Pseudomonas sp. P20. The activities of 2,3-DHBP dioxygenase on catechol and 3-methylcatechol were about 26 to 31% of its activity on 2,3-DHBP, but the enzyme did not reveal any activities on 4-methylcatechol and 4-chlorocatechol.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.8
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• pp.534-541
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• 2014

This study investigated a method to determine an efficient operating condition for the $UV/H_2O_2$ process. The OH radical scavenging factor is the most important factor to predict the removal efficiency of the target compound and determine the operating condition of the $UV/H_2O_2$ process. To rapidly and simply measure the scavenging factor, Rhodamine B (RhB) was selected as a probe compound. Its reliability was verified by comparing it with a typical probe compound (para-chlorobenzoic acid, pCBA); the difference between RhB and pCBA was only 1.1%. In a prediction test for the removal of Ibuprofen, the RhB method also shows a high reliability with an error rate of about 5% between the experimental result and the model prediction using the measured scavenging factor. In the monitoring result, the scavenging factor in the influent water of the $UV/H_2O_2$ pilot plant was changed up to 200% for about 8 months, suggesting that the required UV dose could be increased about 1.7 times to achieve 90% caffeine removal. These results show the importance of the scavenging factor measurement in the $UV/H_2O_2$ process, and the operating condition could simply be determined from the scavenging factor, absorbance, and information pertaining to the target compound.