Mechanistic study on 4, 4'-sulfonylbis removal with CO 2 /Ar gas-liquid DBD plasma

In this study, a single dielectric barrier discharge (DBD) coaxial reactor was used to degrade 4, 4'-sulfonylbis (TBBPS) in water using greenhouse gas (CO 2 ) and argon as the carrier gases. The investigation focused on CO 2 conversion, reactive species formation, gas-liquid mass transfer mechanism, and degradation mechanism of TBBPS during the discharge plasma process. With the decrease of CO 2 /Ar ratio in the process of plasma discharge, the emission spectrum intensity of Ar, CO 2 and excited reactive species was enhanced. This increase promoted collision and dissociation of CO 2 , resulting in a series of chemical reactions that improved the production of reactive species such as ·OH, 1 O 2 , H 2 O 2 and O 3 . These reactive species initiated a sequence of reactions with TBBPS. Results indicated that at a gas flow rate of 240 mL/min with a CO 2 /Ar ratio of 1:5, both the highest CO 2 conversion rate (17.76%) and TBBPS degradation rate (94.24%) were achieved. The degradation mechanism was elucidated by determining types and contents of reactive species present in treatment liquid along with analysis of intermediate products using liquid chromatography-mass spectrometry techniques. This research provides novel insights into carbon dioxide utilization and water pollution control through dielectric barrier discharge plasma technology.