Pulsed high-voltage discharge plasma for degradation of phenol in aqueous solution

Pulsed high-voltage discharge is shown in the present investigation to be effective of phenol degradation in the aqueous solution in an isothermal batch reactor with continuous gas bubbling. Removal of phenol and effects of various parameters on the removal efficiency in the aqueous solution with pulsed high-voltage corona discharge plasma are studied. It is found that phenol degradation can be raised considerably by increasing the peak voltage of the pulsed discharge and the repetition rate of pulse, or by increasing pH of the aqueous solution. Presence of a buffer such as sodium carbonate and/or a hydroxide radical scavenger such as n-butanol in the aqueous solution decreases the removal efficiency of phenol. It is also found that decreasing the diameter of discharge electrode and electric conductivity of the aqueous solution can increase the degradation efficiency. The addition of gas, especially oxygen through the hollow needle electrode, and of FeSO4 to the aqueous solution of phenol is found to significantly enhance phenol degradation. The intermediates formed in the phenol degradation process are pyrocatechol, hydroquinone, resorcinol, 1,4-benzoquinone, and some other unidentified products. The maximum phenol degradation percentage is 62.7% when its residence time is 180 min, and the TOC of aqueous solution decreases by 83.8% after having been discharged for 420 min. The phenol degradation with pulsed high-voltage discharge in aqueous solution shows a first-order kinetics: C = C(0)e(-kt). (C) 2003 Elsevier B.V. All rights reserved.