Degradation of polyethylene microplastics using high-repetition-rate pulsed dielectric barrier discharge plasma in air under mild conditions

Abstract The degradation of microplastics (MPs) using dielectric barrier discharge (DBD) plasma has attracted considerable research attention. However, most existing studies have employed sinusoidal AC high-voltage systems, which have inherent limitations. This study presents an effective method for degrading polyethylene (PE) MPs using a high-repetition-rate pulsed DBD that generates uniform, intense discharges in air. Under conditions of 15 kV and 20 kHz, 0.1 g of PE MPs was completely degraded within 3 h without the use of catalysts or additional carrier gases. Experimental and numerical analyses of the discharge characteristics revealed that plasma-generated energetic electrons facilitated PE degradation while producing various reactive oxygen and nitrogen species. The degradation process initiated at the particle surface, leading to the formation of oxygen- and nitrogen-containing functional groups. Structural, chemical, and surface degradation mechanisms were proposed, and the degradation tendency according to influence of voltage and frequency is presented on degradation was evaluated based on the experimental results. This study advances MP degradation research by enhancing the efficiency of DBD plasma technology and providing deeper insights into the underlying mechanisms.