Photodegradation of F-53B in aqueous solutions through an UV/Iodide system

Advanced reduction by strong reducing hydrated electrons is a promising approach to degrade per-and poly-fluoroalkyl substances (PFAS). This research aimed to investigate the effectiveness of UV/Iodide system for 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA, F-53B) degradation in aqueous solutions. Results from this work demonstrated that UV irradiation with an addition of 0.3 mM KI resulted in 55.99% degradation of F-53B within 15 min and almost 100% within 2 h. The defluorination efficiency of F-53B in the UV/Iodide system was 2.6 times higher than that in the sole UV system after 2 h of irradiation. The degradation efficiency of F-53B was not significantly affected by air purging. The defluorination efficiency with air bubbling, however, was 14.57% lower than that with nitrogen purging. The photodegradation of F-53B in the UV/Iodide system could be well described by a pseudo-first-order kinetic model. Degradation rate constant of F-53B correlated positively with the initial concentration. At 20 mu g/L, the pseudo-first-order rate constant was 5.641 x 10(-2) min(-1) and the half-life was 12.29 min. Higher initial concentration also required less energy input to achieve the same degradation efficiency. The detection and identification of degradation intermediates implied that destruction of F-53B started from dechlorination and followed by continuously flaking off CF2 units.

Automated summary

This study found that the addition of KI in the UV/Iodide system effectively degraded F-53B (6:2 Cl-PFESA), with a degradation efficiency 2.6 times higher than that in the sole UV system. The defluorination efficiency was higher with nitrogen purging compared to air bubbling. The photodegradation of F-53B followed a pseudo-first-order kinetic model. Higher initial concentrations required less energy input to achieve the same degradation efficiency. The study also detected and identified degradation intermediates of F-53B.