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Published March 2011 | public
Journal Article

Kinetics of microwave-enhanced oxidation of phenol by hydrogen peroxide

Abstract

Aqueous solutions of phenol were oxidized by hydrogen peroxide assisted by microwave (MW) irradiation. A simple kinetic model for the overall degradation of phenol in the presence of excess H_2O_2 is proposed in which the degradation rate of phenol is expressed as a linear function of the concentrations of phenol and H_2O_2. A detailed parametric study showed that the degradation rate of phenol increased with increasing [H_2O_2] until saturation was observed. Phenol degradation followed apparent zero-order kinetics under MW radiation or H_2O_2 oxidation. However, after 90 min of irradiation, the observed kinetics shifted to pseudo first order. The overall reaction rates were significantly enhanced in the combined MW/H_2O_2 system, mainly because microwave could accelerate H_2O_2 to generate hydroxyl radical (•OH) and other reactive oxygen intermediates. The observed synergetic effects of the MW/H_2O_2 process resulted in an increased in the net reaction rate by a factor of 5.75. When hydrogen peroxide is present in a large stoichiometric excess, the time required to achieve complete mineralization is reduced significantly.

Additional Information

© 2010 Higher Education Press and Springer-Verlag Berlin Heidelberg. Received November 5, 2009; accepted September 6, 2010. This work was supported by the China Postdoctoral Science Foundation Funded Project (Grant No. 20100471716), Zhejiang Provincial Natural Science Foundation of China (Grant No. Y5100075), and the 3M Corporation. D Zhao was on sabbatical leave at Caltech during the 2008–2009 academic year with support provided by China Scholarship Council and Zhejiang University of Technology.

Additional details

Created:
August 19, 2023
Modified:
October 23, 2023