Achieving efficient removal of sodium p-perfluorous nonenoxybenzenesulfonate (OBS) by DBD plasma through ANN model multi-objective optimization and SHAP analysis

Sodium p-perfluorous nonenoxybenzenesulfonate (OBS), as a novel perfluorinated compound (PFC), has garnered significant attention due to its widespread application. However, its molecular structure is highly stable, making it difficult to degrade. This experiment employs an ANN model and SHAP interpretation method to optimize DBD plasma for highly effective removal of OBS. Under multi-objective optimization of the ANN model (treatment time: 20 min; pH: 4; conductivity: 36 μS/cm; initial concentration: 37.5 mg/L; input power: 40.5 W), the OBS removal rate and energy yield were 91.8 % and 7.659 g/kW•h, respectively. In SHAP analysis, treatment time has the greatest impact on both removal rate and energy yield. Even in the presence of interfering inorganic anions (NO 3 − , HCO 3 − , and Cl − ), DBD plasma could achieve an effective removal rate of over 60 % for OBS. Free radical quenching experiments, density functional theory (DFT), and LC-MS indicate that OBS undergoes under the influence of •OH, •O 2 − , 1 O 2 , and e aq − , involving desulfonation processes, ether cleavage and perfluorinated chain shortening processes. According to ECOASR and T.E.S.T. toxicity analyses, although some toxic byproducts may be generated during the OBS removal process, the environmental risk was low. In complex real-world aquatic environments, the OBS still achieves an effective removal rate exceeding 70 %, demonstrating the broad application prospects of DBD plasma.