Destruction of Volatile Organic Compounds in a Dielectric Barrier Discharge Plasma Reactor

Abstract

The purpose of this study was to optimize the operating conditions for the destruction of VOCs in a dielectric barrier discharge plasma reactor. A representative VOC mixture comprising of s-butanol, toluene, methyl isobutyl ketone and butyl acetate was studied to obtain destruction characteristics. The total concentration of VOCs was initially 100 ppm. The operating parameters studied for optimization were primary voltage (60-110 V AC), frequency (200 - 400 Hz), and relative humidity (0 - 80%). Initial studies were conducted by varying residence time, keeping the other parameters constant, to determine the effect of residence time on destruction efficiency of VOCs. The optimum residence time for operation was 0.2 s in the test reactor. A total VOC destruction of 92% was achieved for a primary voltage of 90 V AC (applied voltage across the reactor was 14916 V AC) and frequency of 300 Hz. In general, overall destruction of VOCs increased with an increase in voltage, frequency, and relative humidity. At 90 V primary and 300 Hz, the overall destruction of VOCs was 91% in dry condition and 96% at 35 - 40% relative humidity. The extent of destruction under the dry conditions was in the following order for the four different test molecules: (S-butanol < Toluene < Butyl Acetate < Methyl Isobutyl Ketone). This order changed in humid conditions, suggesting that the destruction mechanism in humid conditions is different due to presence of OH radicals. Ozone concentration downstream of the reactor increased and stabilized when applied voltage was increased up to 20200 V. With increasing humidity, the ozone concentration downstream was lower. The ozone results showed good agreement with literature observations.