Removal of polyvinyl chloride microplastic by dielectric barrier discharge plasma

Abstract

In this study, polyvinyl chloride (PVC) microplastic was removed by dielectric barrier discharge (DBD) plasma. The removal performance, mechanisms and products were studied. The results show that PVC removal efficiency reached to 85.9% at the optimal condition with 100 min treatment time. Discharge voltage and water content had significant influence on PVC removal efficiency. The removal mechanisms were studied by experiments and density functional theory (DFT) calculations. $e_{aq}^{-}$ was the most powerful reactive substance for PVC removal. OH and H played both positive and negative roles in PVC removal. OH and H can capture $e_{aq}^{-}$, which was not beneficial for PVC removal, but they also reacted with PVC to carry out dehydrogenation and dechloridation reactions. Moreover, charge density difference unveiled that the electron transfer from PVC to OH and H to PVC. $O_2^{·-}$ played a negative role in PVC removal by consuming $e_{aq}^{-}$. The possible degradation pathway of PVC was proposed, and CH site of PVC was the most important reaction site.