Highly efficient removal of perfluorooctanoic acid using synergy of cold Plasma, Sulfate Radicals, and Boron-Doped Graphene-Like Carbon: Insights into synergistic effects and degradation mechanism

Abstract

Advanced oxidation process warrants sustainable processes that can efficiently eliminate organic contaminants from water reservoirs. This study is the first to explore the synergistic effects of cold plasma, persulfate (PS), and boron-doped graphene-like carbon (BDGLC). Plasma activates PS to SO₄^•- along with the production of O₃ and other reactive oxygen species (ROS). For the first time, BDGLC was introduced to plasma + PS system to effectively degrade O₃ from the plasma and convert it into more reactive ^•OH and also to activate PS to SO₄^•-. A novel customized plasma reactor was set up to generate high concentrations of reactive oxygen species (ROS). This novel approach is utilized for the efficient degradation of highly stable and persistent organic pollutants viz. perfluorooctanoic acid (PFOA). The synergy of plasma + PS + BDGLC facilitated 100 % degradation of PFOA within 15 min. The synergy factor of the plasma + PS + BDGLC system was determined to be 1.136, and the value of energy yield (${\eta }_{\mathrm{deg}}$) was 1440.3 mgkW⁻¹h⁻¹. Density function theory calculations, scavenger analyses, and LC-MS analyses revealed the degradation mechanism and ROS involved in the degradation of PFOA. The applicability of the proposed method for the efficient degradation of PFOA in wastewater treatment was validated via actual wastewater studies. This study shows an improved degradation efficiency of PFOA within a shorter period of time and in a higher volume of pollutant solution, with an improved energy utilization efficiency. This research reveals a promising approach for the efficient degradation of highly stable and persistent micropollutants in wastewater in an economic and sustainable manner.