New prototype for the treatment of falling film liquid effluents by gliding arc discharge part I: Application to the discoloration and degradation of anthraquinonic Acid Green 25

Abstract

Gliding arc discharge (GAD) reactors are continuously in progress in order to improve the treatment efficiency of recalcitrant compounds. However, up to now, they remain difficult to transfer to industrial applications because of some technical constraints in their design. In this study, a new efficient pro- totype is proposed for the treatment of gravity falling film shaped of liquid effluents. The liquid flow rate is now continuous as the tank containing the solution to be treated is replaced by an inclined plate along which flows the liquid. The various working parameters are optimized and the new prototype efficiency is tested on discolouration and degradation of the anthraquinonique Acid Green 25. The opti- mized values obtained are: the liquid flow rate ω = 1 L h − 1 , the plate tilt angle ̨ = 45 ◦ and the channel width

= 3 mm. The rates of discolouration and degradation reach 95% and 90% respectively after 12 cycles (180 min) of plasma exposition. The GAD in the presence of humid air generates highly oxidizing radical species such as • OH with a standard potential E ◦ [( • OH/H 2 O) = 2.85 V/SHE] and its reducer agent H 2 O 2 [ E ◦ (H 2 O 2 /H 2 O) = 1.68 V/SHE.