Degradation Performance of 4-Chlorophenol as a Typical Organic Pollutant by a Pulsed High Voltage Discharge System

Degradation of aqueous 4-chlorophenol (4-CP) with air bubbling was experimentally investigated in a multipoint-plate pulsed high voltage reactor. Several important parameters, including electrode distance, liquid conductivity, gas flow rate, and initial concentration, were investigated for 4-CP removal and energy efficiency. After discharge for 90 min, more than 95% of 4-CP was removed at the electrode distance of 1.5 cm, liquid conductivity of 1.06 μS/cm, gas flow rate of 0.75 m 3 /h, and initial concentration of 60 ppm with specific energy density of 450 J/mL. The energy efficiency of 4-CP was about 2.15 × 10 -9 mol/J, and the mineralization of total organic carbon (TOC) reached to 55.8%. Hydrogen peroxide, ozone, nitrite, and nitrate were observed in the liquid phase. 4-chlorocatechol, hydroquinone, 5-chloro-3-nitropyrocatechol, chloride ion, formic, and acetic and oxalic acids were the main byproducts during 4-CP degradation. The degradation pathways were deduced including hydroxylation, N atom attack, and oxygen/ozone oxidation. A kinetic model was established to predict the degradation pathway, and the experimental data were fitted to the developed mathematical model well.