Enhanced degradation of sulfamethoxazole in water using non-thermal plasma-activated persulfate: effects of heat and radical synergies

The treatment of organics in aqueous systems with non-thermal plasma (NTP) technology has shown excellent advantages. However, the effects of spontaneous heat generation and the presence of effective free radicals in the system are often overlooked. This study explores the enhanced degradation of sulfamethoxazole in water using NTP-activated persulfate (PS), with a focus on the synergistic effects of heat and reactive radicals. The results indicate that combining PS (3   mM) with heat (30°C controlled) significantly enhances pollutant removal (30   mg   L –1 ) in the pulsed dielectric barrier discharge reactor. Optimal efficiency reaches an impressive 99.1% elimination rate with a kinetic constant of 0.166   min -1 , using a PS dose ratio of 15:1 and an input power of 64.8   W. Notably, the reaction rate for NTP/PS at 30°C controlled is increased by 97.6% relative to room temperature condition. It demonstrates that the role of heat in a plasma system cannot be ignored. Radical quenching experiments and electron spin resonance tests identify SO 4 • – , •OH, •O 2 – , 1 O 2 , and e⁻ as the major active species contributing to the degradation process. The O 3 and H 2 O 2 play important roles in the production of SO 4 • - and•OH. Besides, the degradation process does not yield any highly toxic by-products, ensuring environmental safety. This research introduces an innovative and environmentally friendly method to enhance the removal of organic pollutants by plasma/PS-heat systems.