[Synergistic Enhancement on Oxidation of Phenol by Fenton Processes by Adding Ce³⁺ and Cu²⁺ Ions]

Synergistic effect of Ce³⁺ and Cu²⁺ on the oxidation efficiency of phenol in different initial pH and H₂O₂ concentrations by Fenton processes was studied. The experiment results illustrated that Ce³⁺/Cu²⁺/Fe²⁺/H₂O₂ system had a wider scope of application than Fenton process in the aspect of pH and H₂O₂ concentration. Phenol was still efficiently degraded by Ce³⁺/Cu²⁺/Fe²⁺/H₂O₂ at a higher pH (pH=5.0) and a higher H₂O₂ concentration (2.0 mmol·L^-1). In addition, Cu²⁺ could react with quinone-like substrates, the oxidation intermediates of phenol, to produce Cu⁺, which could catalyze the decomposition of H₂O₂ to form·OH, while Ce³⁺ could accelerate the formation of quinone-like substrates and facilitate the cycling of Fe³⁺ and Fe²⁺, to enhance the decomposition of H₂O₂ to form·OH, the mechanism analysis illuminated the synergy of Ce³⁺ and Cu²⁺. The reactive species in Ce³⁺/Cu²⁺/Fe²⁺/H₂O₂ system was still proved to be·OH, resulting from the scavenging experiments by adding different radical scavengers.