Cellular foam-based trickle-bed DBD reactor for plasma-assisted degradation of tetracycline hydrochloride

Non thermal plasma (NTP) is a promising technology for degrading organic pollutants in water/wastewater, in which the transfer of energetic species at the interface between gas discharge and liquid phase is key to improve degradation efficiency. Herein, this work shows the development of an integrated system of dielectric barrier discharge (DBD) plasma and open-cell ceramic foam (CF) for the degradation of tetracycline hydrochloride (TCH, a model antibiotic) in liquid film. Specifically, a bespoke trickle-bed DBD reactor with liquid distributor was developed to enable the formation of uniform liquid film on the surface of the hydrophilic CF strut. Due to the improved mass transfer across the thin liquid film, the trickle-bed DBD reactor with the hydrophilic CF exhibited the comparatively highest TCH removal efficiency (>80%) and energy efficiency (viz., EETCH removal of ∼0.6 g kWh−1) among the systems under investigation such as the glass bead packed DBD. The findings showed that the presence of liquid film was beneficial to the propagation of homogeneous plasma discharge in the CF bed and promoted the mass transfer of active species from plasma discharge to liquid, and thus improved the TCH degradation efficiency. Results from quenching experiments suggested that the electron induced active species (especially O2−) played the important role in degrading TCH rather than electrons.