Polymerization Effects of Ozone: Applications to the Removal of Phenolic Compounds from Industrial Wastewaters

Abstract

Degradation of phenols by ozone has been extensively studied but the oxidative coupling pathway of ozone resulting in a phenol polymerization has not been largely investigated. Application of low ozone dose in solutions of 2.4 dichlorophenol and salicylic acid is characterized by the formation of high molecular compounds which are partially insoluble. Numerous polymers have been identified by gas chromatography coupled with mass spectrometry. Application of the polymerization effect of ozone to petrochemical and coking wastewaters containing phenols give similar results. In each case, phenolic compounds are efficiently removed, even if a large organic content is present. In the case of petrochemical wastewater, where phenols represent only 30% of TOC, the ozone effects are not sufficient to merit an ozonation step on the present treatment line. On the other hand, when phenols represent the greater part of the organics, as in coking wastewater, an important fraction of insoluble compounds, easily removed by filtration, are formed.

Influence of Wastewater Particles on Ozone Degradation of Trace Organic Contaminants

“…The increase in TSS in the filtered sample may indicate the formation of particles (and TSS) by ozone-induced polymerization/flocculation of DOM. 11,16 This phenomenon was not seen in the nonfiltered effluent, probably due to equilibrium between the formation and disintegration of particles by ozone. The decrease in COD f by ozone in the filtered effluent, as opposed to the unchanged COD f level in the nonfiltered effluent, demonstrates once again the simultaneous reaction of ozone with particles and DOM (thus with less particles, more ozone reacts with DOM).…”

“…15 In addition, ozone was shown to form particles through DOM polymerization. 16 With respect to disinfection, particles can protect embedded microbes, as ozone penetration into particles is limited. 17 Dietrich et al 14 suggested that ozone inactivation of microbes associated with particles (>6 μm) will take place only at high ozone dose because of slow intraparticle ozone diffusion, and the preferential reaction of ozone with DOM.…”

Reactions of phenol-OH-adduct radicals. Phenoxyl radical formation by water elimination vs. oxidation by dioxygen

“…In the pulse radiolysis of a N 2 O-O 2 (4 : 1)-saturated solution of phenol containing tetranitromethane (TNM, 3 × 10 Ϫ4 mol dm Ϫ3 ), the absorption of the nitroform anion (NF Ϫ ) at 350 nm increases rapidly following an initial jump, which is due to the reaction of HO 2 ؒ -O 2 Ϫ from primary hydrogens [reactions (10), ( 16) and ( 17)] with TNM [reaction (18)].…”

“…Ϫ corresponds approximately to the sum of the o-and p-OH-adduct radicals. Since reaction (18) is not the ratedetermining step (k 18 = 1.9 × 10 9 dm 3 mol Ϫ1 s Ϫ1 ), 33 the rate constant determined above (1.3 × 10 5 s Ϫ1 ) is thus the overall rate of HO 2 ؒ -elimination of the peroxyl radicals of these two isomeric dihydroxycyclohexadienyl radicals [e.g., reactions ( 14), ( 15) of the p-OH-adduct-radical].…”

Destruction of phenol from wastewater by oxidation with sulfite-oxygen

“…Chemical oxidation of phenolic wastes offers an alternative treatment method to destroy phenolics totally. In recent years oxidation by pure oxygen and ozone gas has received a great attention (Zimmermann, 1950; Randall and Knopp, 1980; Pruden and Le, 1976; Randall et al, 1985;Sadana and Katzer, 1974a,b; Walsh and Katzer, 1973; Vatistas and Gurol, 1987; Augugliaro and Rizzutti, 1978; Nekouinaini and Gurol, 1984;Duguet, 1987;Eisenhauer, 1964;Seim, 1959). Similarly, the oxidation of phenol has been carried out by using H202 (Greenberg et al, 1978), permanganate, chlorine (Eisenhauer, 1964), and hypochlorite (Barbeni, 1987).…”