Degradation of aniline in aqueous solution using non-thermal plasma generated in microbubbles

Aniline is carcinogenic and toxic to human and aquatic life. A long treatment time and the addition of chemicals are usually necessary to remove aniline from water. In this study a novel approach, dielectric barrier discharge (DBD) combined with microbubbles (MBs), was employed to degrade aniline in aqueous solution. The aniline removal rates with DBD/MB were influenced by input power, bubble sizes, initial pH, the existence of a buffer solution, and initial conductivity. Compared to counterpart that did not use MBs, the DBD/MB process significantly enhanced aniline degradation and mineralization. Hydroxyl radicals were identified as the primary active species responsible for aniline degradation used electron spin resonance and the free-radicals inhibitor tertiary-butyl alcohol. This study revealed that the DBD/MB combination could enhance the dissolution and mass transfer of plasma-generated active species from the gas to liquid phase, and furthermore, that MBs collapsed under water surface increased production of hydroxyl radicals and promoted aniline degradation. Thus, employing MBs to enhance the reactive capacity of a DBD reactor may contribute to the development of an alternative method to degrade recalcitrant chemicals since it does not need any dosing with chemicals.