Ozone of phenols

Singer PC, Gurol MD. 1983. Dynamics of the ozonation of phenol. I. Experimental observations. Water Res 17 1163-1171. 

Seventy-five milliliters of samples were collected from reaction column upper end at different time intervals during the ozonation reaction for the determination of the by products. Ozonation of phenol was carried out at four different initial concentrations, 25, 50, 75 and 100 mg/L, with three different ozone concentrations 2, 4 and 6 g/L h. 

Ozonization of phenol in water resulted in the formation of many oxidation products. The identified products in the order of degradation are catechol, hydroquinone, o-quinone, cis,ds-muconic acid, maleic (or fumaric) and oxalic acids (Eisenhauer, 1968). In addition, glyoxylic, formic, and acetic acids also were reported as ozonization products prior to oxidation to carbon dioxide (Kuo et al, 1977). Ozonation of an aqueous solution of phenol subjected to UV light (120-W low pressure mercury lamp) gave glyoxal, glyoxylic, oxalic, and formic acids as major products. Minor products included catechol, hydroquinone, muconic, fumaric, and maleic acids (Takahashi, 1990). Wet oxidation of phenol at 320 °C yielded formic and acetic acids (Randall and Knopp, 1980). 

The importance of a correct evaluation of kLa(03) or kla 02) was confirmed in a study on the simulation of (semi-)batch ozonation of phenol (Gurol and Singer, 1983). It was shown that a close match between the measured and the calculated data was only obtained when kLa(02) was measured as a function of the residual phenol concentration. The oxygen mass transfer coefficient was observed to change from kLa(02) = 0.049 s 1 at c(M) = 50 mg IF1 phenol to kLa(02) = 0.021 s- at c(M) = 5.0 mg L 1 phenol. 

Gurol M D, Singer P C (1983) Dynamics of the Ozonation of Phenol - II Mathematical Model, Water Research 16 1173-1181. 

Finally, Sotelo et al. [179], while studying the ozonation of resorcinol and phloroglucinol, two precursors of trihalomethanes (THM) during water chlorination, found some polar intermediates that confirmed the proposed phenol mechanism reported elsewhere [42]. From the identified intermediates it was deduced that ozonation of phenols yields more oxygenated compounds that eventually could be removed in biological steps. 

Y Yamamoto, E Niki, H Shiokawa, Y Kamiya. Ozonation of organic compounds. 2. Ozonation of phenol in water. J Org Chem 44 2137-2142, 1979. 

The reactions of ozone with mono- and dihydroxybenzenes have provoked so far a particular interest (1,2,34,73-75,77-79), namely, because of their great importance for environment protection, chemical stabilization and the theory of reactivity. The ozonation of phenol, pyrocatechol, resorcinol and hydroqui-none has been studied in different solvents - aqueous and organic, aimed at the deriving of the kinetic parameters and product composition [21-24, 80-86). The rate constants of phenol and resorcinol ozonation in water at room temperature are 1.3 x 10 M . s and >3 x 10 M. s", respectively, whereas the rate constants of benzene, toluene and anisole ozonation in organic media are 2,14 and 2.9 x KFM. s- [72-75],... 

Catalytic ozonation of phenolic compounds the case of gallic acid. Appl. 

Phenols. The first stable ozone oxidation product of phenol in water is ds ds-raucomc acid, which requires - 2 mol O /mol phenol. In practice, larger dosage levels of ozone are required because other ozone-reactive substances are present in most wastes. Ozone oxidation of phenoHc effluents is employed in paper mills, coke mills, oil refineries, and thermoplastic resin manufacture, producing effluents that are safe to freshwater biota (122,123) (see Lignin Pulp). 

Other Hydroperoxides. Several hydrotrioxides including alkyl hydrotrioxides, R—OOOH, have been reported (63,64). There is strong spectroscopic evidence that a-cumyl hydrotrioxide [82951-48-2] is produced in the low temperature ozonization of cumene. Homolytic decomposition of a-cumyl hydrotrioxide in cumene/acetone-hindered phenol resulted in cumyl alcohol as the only organic product (65). Based on the... 

Oxidation of phenols with chlorine dioxide or chlorine produces chlorinated aromatic intermediates before ring rupture. Oxidation of phenols with either chlorine dioxide or ozone produces oxidized aromatic compounds as intermediates which undergo ring rupture upon treatment with more oxidant and/or longer reaction times. In many cases, the same nonchlorinated, ringruptured aliphatic products are produced using ozone or chlorine dioxide. 

Kinetic Parameters of Phenols and Amines Reactions with Hydroperoxides, Dioxygen, Ozone, and Nitrogen Dioxide in IPM Model [4,110-114]... 

Gould JP, Weber WJ, Jr. 1976. Oxidation of phenols by ozone. J Water Pollut Control Fed 48 47-60. 

The Degradation Kinetics of Phenol Solntions with Ozone... 

In this study, synthetic aqueous solutions of phenol were treated with ozone. The reaction of ozone with phenol was investigated at several conditions, such as different phenol and ozone concentrations, and contact times. Total Organic Carbon (TOC) and UV analysis of the aromatic by-products formed during and after the ozonation reaction were employed. The reaction rates calculated from TOC analysis were investigated. 

In this study, the degradability of phenol in aqueous solutions was investigated with using ozone. Additionally, decomposition kinetic of phenol in the presence of ozone was calculated using maximum rate constants, from graphics of concentration versus time. 

The UV absoibance is used for the preliminary control of the degree of decomposition. The GC/MS and HPLC analysis are used to identily intermediate and final products formed during ozonation. It was found that reaction of ozone with phenol at pH 9, in addition to catechol (C) and hydroquinone (HQ) are likely primary oxidation products, p-benzoquinone (PBQ) and o-benzoquinone (OBQ), the others are more oxidized species, and CO and water the final oxidation products. The detected degradation products are shown in Scheme 24.1. 

TOC and phenol concentration decreased same trend and the forming of by product was determined by mass spectrum. It was shown that formed by product was not stabile, whereas it immediately decomposes to different products. It was also determined that the amounts of ozone were sufficient for phenol decomposing. As a result of kinetic investigation of phenol, decomposition reaction was found first order because of obtaining almost constant k values (Fig. 24.2a-f). As expected... 

Anticipated products from the reaction of phenol with ozone or OH radicals in the atmosphere are dihydroxybenzenes, nitrophenols, and ring cleavage products (Cupitt, 1980). Reported rate constants for the reaction of phenol and OH radicals in the atmosphere 2.8 x 10 " cmVmolecule-sec at room temperature (Atkinson, 1985) and with NO3 in the atmosphere 2.1 x lO" cmVmolecule-sec at 296 K (Atkinson et al., 1984). 

It is a common phenomenon for phenolic moieties to accumulate in plant tissues after exposures to stresses. Concentrations of phenols are increased in ozone-treated plant tissues (3, ). Reddish-brown polymerized pigments also develop in a diversity of plants injured by ozone. This response appears to be a general reaction and not a specific result of ozone injury ( ). Similar pigments have been identified in plant tissues during senescence and by curing processes ( ). 

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