4-chlorophenol, decomposition

Benitez, F.J., Beltan-Heredia, J., Acero, J.L., and Rubio, F.J., Contribution of free radicals to chlorophenols decomposition by several advanced oxidation processes, Chemosphere, 41, 1271-1277, 2000. 

Benitez FJ, Beltran-Heredia J, Acero JL, Rubio FJ (2000) Contribution of Free Radicals to Chlorophenols Decomposition by Several Advanced Oxidation Processes, Chemosphere 41 1271-1277. 

Baker MD, Mayfied Cl. 1980. Microbial and nonbiological decomposition of chlorophenols and phenol in soil. Water Air Soil Pollut 13 411-424. 

Walker N. 1954. Preliminary observations on the decomposition of chlorophenols in soil. Plant Soil 5 194-204. 

Scheme 4.2. Sonochemical decomposition of 4-chlorophenol in aerated water.

The polymers prepared by Hunter from polyhalophenols were undoubtedly highly branched. He examined the decomposition of salts of 2.6-dibromo-4-chlorophenol, 2.6-dichloro-4-bromophenol and 2.6-diiodo-4-chlorophenol (44). By analysis of the resulting polymers he was able to determine qualitatively (Table 6) the order of reactivety of the halogens (I>Br>Cl) and furthermore established that considerable reaction occurs through the o-position. 

Shen et al. (1995) investigated the effect of light absorbance on the decomposition of aqueous chlorophenols (CPs) by UV/H202. The photoreaction system was batch annular photoreactors with 254-nm, low-pressure UV lamps at 25°C. The light absorbance and photolytic properties of chlorophenols and H202 were found to be highly dependent on the solution pH and can be adequately described with the linear summation of the light absorbance of undissociated and dissociated species of chlorophenols ... 

Sonolytic decomposition of chlorophenol in water was enhanced in the presence of Fe(II), assuming that the Fenton oxidations occur ... 

Decomposition rates for selected chlorophenols in UV/H202 oxidation system. (Data from Benitez, F.J. et al., Chemosphere, 41,1271-1277, 2000.)... 

Ferrihydrite catalysis of hydroxyl radical formation from peroxide has also shown experimental results consistent with a surface reaction [57]. The yield of hydroxyl radical formation was lower for ferrihydrite than for dissolved iron, resulting in a higher peroxide demand to degrade a given amount of pollutant. As mentioned above, although ferrihydrite exhibited a faster rate of peroxide decomposition than goethite or hematite, the rate of 2-chlorophenol degradation with these catalysts was fastest for hematite [55], In other studies, quinoline oxidation by peroxide was not observed when ferrihydrite was used as catalyst [53]. 

Huang H-H, Lu M-C, Chen J-N. Catalytic decomposition of hydrogen peroxide and 2-chlorophenol with iron oxides. Water Res 2001 35 2291-2299. 

Also electrochemical oxidation of 4-chlorophenol performed in H2SO4 medium, in the potential region of electrolyte decomposition resulted in a complete incineration of reactant by electrogenerated OH radicals (Rodrigo et al. 2001). 

In the late 1970s HPLC provided an ideal tool for the analysis of pollutants and other environmental contaminants. Techniques were developed for analyzing chlorophenols, pesticide residues, and metabolites in drinking water and soil (parts per trillion) and trace organics in river water and marine sediments, and for monitoring industrial waste water and polynuclear aromatics in air. Techniques were also developed for determining fungicides and their decomposition products and herbicide metabolites in plants and animals. 

The combination of photo-Fenton and ozonation results in an important enhancement of the destruction efficiency of organic compounds like phenol [96], 2,4-D [97], aniline or 2,4-chlorophenol ([33] and references therein). As mentioned in Sect. 2.5.1, metal ions catalyze ozone decomposition. In the dark, Fe(II) catalyzes O3 degradation giving the ferryl intermediate (Fe02+, see Sect. 2.6.9), which can directly oxidize the organic pollutant or evolve to a hydroxyl radical ... 

Mills et al. performed extensive investigations into the photocatalytic degradation of 4-chlorophenol. These included studies on the effects of different titania samples [102], effects of annealing temperature on the photocatalytic efficiency of titania [ 103] and a mechanistic study of the decomposition process. The rate of chlorophenol destruction was found to drop when using titania photo catalysts that had been heated above 600 °C. This was believed to be due to a build up of the rutile phase and a reduction of surface area following heat treatment above these temperatures. A number of intermediates were reported including 4-chlorocatechol, hydroquinone, benzoquinone and 4-chlororesorcinol [104],... 

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