Mechanism of the oxidation of aqueous phenol with dissolved oxygen

Abstract

The oxidation of aqueous phenol by oxygen has been studied at elevated temperature and pressure by use of the stopped flow technique. High performance liquid chromatography has been used to identify the oxidation products and estimate their concentrations. A detailed reaction mechanism is proposed.

Wet air oxidation of phenol using active carbon as catalyst

“…Phenol is a relatively strong acid, which confers acidic properties to the feed solution (pH5.9). In addition, the reaction intermediates from the complex phenol oxidation mechanism are mostly organic acids [35], which make the conditions more acidic throughout the reactor. This means that the most weakly bonded catalytic species in the support are progressively dissolved so the catalyst activity quickly decreases.…”

Carbon materials and catalytic wet air oxidation of organic pollutants in wastewater

“…Moreover, it seems that benzoquinone and formic acid are formed at earlier space times than 4-HBA and maleic acid, respectively. This suggests that phenol oxidation over the CI carbon may proceed by two parallel routes, the 4-HBA destruction path being a new route in the Devlin and Harris reaction scheme of phenol WAO [207]. The complete network proposed from the experimental data for the CWAO of phenol over the CI carbon can be depicted from figure 20.…”

“…Based on the pioneer work of Devlin and Harris [207] on phenol WAO, detailed oxidation pathways of pure phenol [64,65,79,119,122,125,160,[208][209][210][211], phenolic compounds [64,124,212] and carboxylic acids [72,122,125,127,130] were experimentally assessed for different catalysts including activated carbon [79,160] and activated carbon supported Ru, Pt, Pd metals [119,122,125,127,130,211]. The distribution of partial oxidation products obtained in phenol CWAO essentially involved the same species as those found by Devlin and Harris.…”

Stability of 40 phenolic compounds during ultrasound-assisted extractions (UAE)

“…Furthermore, the oxidative degradation of phenolic in aqueous solution by low reactivity molecular oxygen can be described with a free radical autoxidation. This confined to the initiating reactions with certain temperature (and pressure) that overcome the energy barrier required for the reaction of molecular oxygen towards organics [19]. In the case of coumaric acid, the concept of phenolic hydrogen provides the resonance-stabilized phenoxy radical that has a half-filled orbital with the highest spin densities at the ortho and para positions.…”