Solar-driven photothermal activation of peracetic acid for efficient micropollutant degradation: Mechanisms, toxicity assessment and reusability

Advanced oxidation processes utilizing peracetic acid (PAA) have garnered significant interest for the removal of micropollutants, while the mechanisms of employing both the light and thermal energy of solar radiation to activate PAA have not been explored. This study adopted the reduced graphene oxide (rGO) as a photothermal material under solar radiation to synergistically activate PAA for the degradation of carbamazepine (CBZ). The temperature notably increased to a maximum of 63.0 °C under the rGO concentration of 5 mg/L, and an optimal removal efficiency of 92.45 % with a k obs of 0.014 min −1 was achieved. The primary mechanism for CBZ removal was the generation of reactive species through the photoactivation and thermal activation of PAA under solar irradiation. Radical quenching experiments and electron spin resonance analysis identified CH 3 C(O)OO· as the principal contributor to CBZ degradation. Seven potential transformation products of CBZ were identified, and three possible degradation pathways were proposed. The toxicity of CBZ polluted water was effectively reduced after photothermal-activated PAA treatment. The removal efficiency of CBZ remained above 90 % after four consecutive cycles of rGO reuse. This study comprehensively elucidates the mechanism of photothermal activation of PAA and thus contributes to the degradation of micropollutants.