Studies on the oxidation of phenols catalyzed by a copper(II)–Schiff base complex in aqueous solution under mild conditions

Abstract

The catalytic oxidation of phenol with hydrogen peroxide using a synthetic copper(II)-Schiff base complex as catalyst has been investigated in phosphate buffer at pH 7 and 25• C. In order to further investigate the reaction pathway, the catalytic oxidation of hydroquinone, p-benzoquinone and catechol were also studied under the same conditions. These reactions were found to be pseudo-first-order with respect to the concentration of phenolic substances. The rate constants were also calculated. In the presence of catalyst, the kinetics and the HPLC analysis showed that for the first step phenol was oxidized to hydroquinone and catechol, and the catalyst easily promoted the formation of hydroquinone but not catechol, for the second step the dihydroxybenzenes were further oxidized to benzoquinone, and lastly short-chain acids, including maleic acid and oxalic acid, were formed. The activity of the catalyst hardly decreased during the whole reaction. Addition of imidazole accelerated the oxidation of phenol. The catalytic decomposition of hydrogen peroxide using this catalyst was also investigated.

Kinetic study of the manganese‐based catalytic hydrogen peroxide oxidation of a persistent azo‐dye

“…Conditions for first-order kinetics are fulfilled as presented in Case 1 of the kinetic model. 31 Kondru et al (2009) 32 and Meng et al (2006). 33 In this work, a catalyst concentration of 500 ± 5 mg L −1 was suggested as the optimum value since higher catalyst concentrations gave almost similar results.…”

Removal of phenolic endocrine disrupting compounds from waste activated sludge using UV, H2O2, and UV/H2O2 oxidation processes: Effects of reaction conditions and sludge matrix

“…Zhou et al (2004) observed that the photo-oxidation efficiencies were dependent on pH values and ferric/oxalate concentration ratios in water. Meng et al (2006) indicated that oxidation of phenols catalyzed by a copper Schiff base complex in aqueous solution. Target compounds With 0.5 M scavenger Without scavenger Fig.…”

Photodegradation of bisphenol a induced by metal ions in aqueous solution in the presence of ascorbic acid

“…Sykora [24] reviewed the photochemical behavior of copper complexes and indicated that the presence of Cu 2+ and another reactant (catalyst) can lead to enhancement of pollutant photodegradation. Meng et al [25] studied on the oxidation of phenols catalyzed by a copper ( )-schiff base complex in aqueous solution. Uchida and Kawakishi [26] investigated the degradation of ȕ-cyclodextrin induced by Cu 2+ in the presence of ascorbic acid.…”