2.4.6- trichlorophenol degradation

Louie TM, CM Webster, L Xun (2002) Genetic and biochemical characterization of a 2,4,6-trichlorophenol degradation pathway in Ralstonia eutropha JMP134. J Bacterial 184 3492-3500. 

Maltseva O, P Oriel (1997) Monitoring of an alkaline 2,4,6-trichlorophenol-degrading enrichment culture by DNA fingerprinting methods and isolation of the responsible organism, haloalkaliphilic Nocardioides sp. strain M6. Appl Environ Microbiol 63 4145-4149. 

The a-isomer of hexachlorocyclohexane exists in two enantiomeric forms, and both are degraded by Sphingomonas paucimobilis strain B90A by dehydrochlorination to 1,3,4, 6-tetrachlorocyclohexa-l,4-diene that is spontaneously degraded to 1,2,4-trichlorophenol. 

Azotobacters. Burk and Winogradsky in the 1930s showed that these could readily be obtained from soil samples by elective enrichment with benzoate. The degradative pathway for benzoate has been elucidated (Hardisson et al. 1969), and the range of substrates extended to 2,4,6-trichlorophenol (Li et al. 1992 Latus et al. 1995). The enzyme from Azotobacter sp. strain GPl that catalyzes the formation of 2,6-dichlorohydroquinone from... 

Briglia M, FA Rainey, E Stackebrandt, G Schraa, MS Salkinoja-Salonen (1996) Rhodococcus percolatus sp. nov., a bacterium degrading 2,4,6-trichlorophenol. Int J Syst Bacterial 46 23-30. 

Li D-Y, J Eberspacher, B Wagner, J Kuntzer, F Lingens (1992) Degradation of 2,4,6-trichlorophenol by Azotobacter sp. strain GPl. Appl Environ Microbiol 57 1920-1928. 

Degradation of contaminants may occur with bacteria that have been isolated from pristine environments without established exposure to the contaminants, and exhibit no dependence on substrate concentration. For example, organisms from a previously unexposed forest soil were able to degrade 2,4,6-trichlorophenol at concentrations up to 5000 ppm, and terminal restriction fragment length polymorphism analysis revealed that at concentrations up to 500 ppm, the bacterial community was unaltered (Sanchez et al. 2004). 

Kiyohara H, T Hatta, Y Ogawa, T Kakuda, H Yokoyama, N Takizawa (1992) Isolation of Pseudomonas pick-ettii strains that degrade 2,4,6-trichlorophenol and their dechlorination of chlorophenols. Appl Environ Microbiol 58 1276-1283. 

Sanchez MA, M Vasquez, B Gonzalez (2004) A previously unexposed forest soil microbial community degrades high levels of the pollutant 2,4,6-trichlorophenol. Appl Environ Microbiol 70 7567-7570. 

The degradation of 2,4,6-trichlorophenol has been examined in a number of bacteria. Monooxygenation plays a key role, and 2,6-dichlorobenzoquinone and 6-chlorohydroxy-quinol have been recognized as intermediates ... 

Joshi DK, MH Gold (1993) Degradation of 2,4,5-trichlorophenol by the lignin-degrading basidiomycete Phanerochaete chrysosporium. Appl Environ Microbiol 59 1779-1785. 

Reddy GVB, MDS Gelpke, MH Gold (1998) Degradation of 2,4,6-trichlorophenol by Phanerochaete chrysosporium. involvement of reductive dechlorination. J Bacteriol 180 5159-5164. 

The photocatalytic activity of ZnO nanomaterials for the degradation of some organic pollutants in water [173] (e.g., dyes [174]) was explored by several groups to achieve environmental benefits. Recent studies have indicated that ZnO can be used under acidic or alkaline conditions with the proper treatment [175,176]. ZnO nanomaterials were used as photocatalysts for the degradation of phenol [177] and chlorinated phenols such as 2,4,6-trichlorophenol [178]. ZnO nanomaterials were also used for the degradation of Methylene Blue [179], direct dyes [180], Acid Red [181], and Ethyl Violet [182],... 

ZnO photocatalyst can also be coupled with other materials in order to improve its chemical and physical properties [183] and photocatalytic activity [184]. Nanosized ZnO was immobilized on aluminum foil for the degradation of phenol [185]. Lanthanum and ZnO were combined to degrade 2,4,6-trichlorophenol [186]. Compared with Ti02 nanomaterial, ZnO nanomaterial generally absorbs a significant amount of the solar spectrum in the visible range therefore, ZnO nanomaterials were combined with Ti02 nanomaterials used as a photocatalyst [187]. 

Anandan, S., Vinu, A., Mori, T., Gokulakrishnan, N., Srinivasu, P., Murugesan, V. and Ariga, K. (2007) Photocatalytic degradation of 2,4,6-trichlorophenol using lanthanum doped ZnO in aqueous suspension. Catalysis Communications, 8, 1377-1382. 

Al-Ekabi, H., N. Serpone, E. Pelizzetti, C. Minero, M. A. Fox, and R. B. Draper (1989), "Kinetic Studies in Heterogeneous Photocatalysis. 2. Ti02 Mediated Degradation of 4-Chlorophenol Alone and in a 2,4-Dichlorophenol, and 2,4,5-Trichlorophenol in Air-Equilibrated Aqueous Media," Langmuir 5, 250-255. 

A similar combination of ultrasound and photocatalysis has also been reported to destroy 2,4,6-trichlorophenol in aqueous solution [39]. An ultrasonic probe (22 kHz) with a uv light source (15 W) was used to examine the effect of changing such operating conditions as ultrasonic intensity, reaction temperature and uv transmission. The experiments involved using 2,4,6-trichlorophenol (100 ppm) and TiOj (0.1 g L ) and showed that the degradation rates increased with the temperature of the solution. The cumulative effect was more pronounced at lower ultrasonic intensities with little additional benefit derived at increased ultrasonic powers. 

Soil Under aerobic conditions, indigenous microbes in contaminated soil produced pentachlorocyclohexane. However, under methanogenic conditions, a-BHC was converted to chlorobenzene, 3,5-dichlorophenol, and the tentatively identified compound 2,4,5-trichlorophenol (Bachmann et al., 1988). Manonmani et al. (2000) isolated a microbial consortium from sewage and soil that could completely mineralize a-BHC in 14 d at 30 °C. The acclimated consortium could degrade up to 100 mg/L of a-BHC within 72 h at a degradation rate of 58 mg/L-day. 

Pentachlorophenol degraded in anaerobic sludge to 3,4,5-trichlorophenol, which was reduced to 3,5-dichlorophenol (Mikesell and Boyd, 1985). In activated sludge, only 0.2% of the applied amount was mineralized to carbon dioxide after 5 d (Freitag et al., 1985). 

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