Unveiling the decomposing and mineralizing mechanism of novel perfluoroalkyl acid via hydroxyl radical dominated electrochemical oxidation

A cerium-doped Sb2S3 anode is successfully fabricated for perfluoroalkyl acids (PFAAs) degradation via a hydroxyl radical dominant electrochemical oxidation (EO) coupled peroxymonosulfate (PMS) reaction. Various PFAAs can be efficiently removed within 25 min with high mineralization and low energy consumption. The hydroxyl radical, sulfate radical, and electron transfer are responsible for PFAAs degradation, and the hydroxyl radical played a dominant role. The electron can be moved from the highest occupied molecular orbital of these PFAAs to the lowest unoccupied molecular orbital of PMS via potential energy difference, further decomposing PMS to generate hydroxyl and sulfate radical for PFAAs degradation. Besides, the corresponding degradation pathway, defluorination, and Gibbs free energy of the reaction for each PFAAs were elucidated based on the identified intermediates and density functional theory calculations. The current study provides insight into the efficient decomposition mechanism of various PFAAs during EO and highlights its promising potential in environmental remediation.