Abstract
A cylindrical wetted-wall corona discharge reactor was used for removal of acetaldehyde from gas mixture of O2 and N2. The reactor consists of a wire cathode stretched along the axis of a cylindrical anode. The gas mixture was continuously fed through the reactor in one pass, whereas water was circulated as a falling thin film on the inner wall of the anode. Short-lived species such as ions and radicals as well as ozone are produced in the reactor by gas corona reactions. When some of these short-lived species drift and reach the water film, reactive OH radical is produced in the water. Gaseous acetaldehyde was mainly removed from gas stream by absorption, meanwhile absorbed acetaldehyde in water was decomposed by aqueous radical, OH, resulting in sustainable removal of acetaldehyde. Ozone oxidation did not significantly contribute to removal of acetaldehyde under the present condition and gaseous acetaldehyde was not effectively removed in absence of oxygen. When oxygen coexisted in gas mixture at 5%, acetaldehyde was removed effectively resulting in sustainable removal of acetaldehyde. However, an increase in oxygen concentration caused the decreasing removal extent when the corona current was excessively high. This is because corona-induced turbulence broadened the residence time distribution of gas in the reaction zone. Moreover, oxygen strongly influenced the decomposition of aqueous acetaldehyde and TOC in water. There were a minimum current and a maximum inlet concentration of gaseous acetaldehyde leading to steady state operation because aqueous acetaldehyde and TOC could be effectively decomposed. There was no significant by-product detected in treated gas.
