Effect of Fullerene C60 on Sulfate Formation during Gas-Phase Oxidation of SO2 by H2O2
Fullerene (C60) is an emerging atmospheric pollutant that may influence sulfate formation during haze events. This study investigated the effect of C60 on sulfate production in the gas-phase oxidation of SO2 by H2O2 using a flow tube reactor. Results demonstrated that the presence of C60 significantly increased sulfate yields. Control experiments varying C60 loading, H2O2 concentration, and ultraviolet (UV) irradiation revealed that higher C60 amounts, elevated H2O2 levels, and UV exposure enhanced the promoting effect. Mechanistic investigations via free radical trapping and X-ray photoelectron spectroscopy (XPS) indicated a pre-adsorption-oxidation pathway. XPS analysis showed electron transfer on the C60 surface, converting adsorbed S(IV) to S(VI), confirming direct participation of C60 in sulfate formation. Radical trapping experiments and model calculations confirmed that C60 promotes the generation of hydroxyl radicals (·OH) and superoxide radicals (·O2−), which are key oxidants driving SO2 conversion to sulfate. The study reveals that C60 particles markedly enhance atmospheric sulfate formation, offering a novel pathway for understanding sulfate generation mechanisms. These findings have implications for air quality modeling and haze mitigation strategies, as C60 may act as a catalytic surface for sulfate production in polluted atmospheres.