Mechanism and kinetics of 2-chlorophenol decomposition using coupled ultrasound and electrocatalysis

摘要

A coupled ultrasound/electrocatalysis(US/EC) process was used to enhance the decomposition effi-ciency of organics.The synergetic kinetics and the mechanism of 2-chlorophenol(2-CP) decomposi-tion with coupled US/EC were studied.It was found that in a US/EC process 2-CP is attacked by active radicals(such as hydroxyl radicals) to form 2-chloro-p-benzoquinone,and the latter is oxidized to simple organic acids when the ring is opened.The enhancement factor expressed by the apparent rate constant of 2-CP decomposition with coupled US/EC is 1.324 at a current density of 20 mA·cm-2,an ultrasonic frequency of 20 kHz,an ultrasonic intensity of 0.27 W·cm-2,and a 2-CP initial concentration of 200 mg·L-1,which means that a synergetic effect exists.A model derived from Langmuir adsorption theory of solid surface and reaction kinetics equations can describe exactly the decomposition of 2-CP with coupled US/EC.The numerical values are in good agreement with the experimental data.The model parameters are associated with reaction conditions.