As peracetic acid (PAA) is being increasingly used as an alternative disinfectant, efficient activation of PAA by low-cost and environmentally friendly catalysts over a wide pH range is potentially useful for simultaneous sterilization and pharmaceutical degradation in wastewater. In this study, PAA was successfully activated by sulfur-containing minerals (25 mg/L FeS) for efficient oxidative removal of three pharmaceuticals (10 μM) over a wide pH range (3.0−9.0): 80−100% removal efficiency within 5 min, and the whole pharmaceuticals can be removed after reaction of 10 min. As expected, surface Fe(II) rather than sulfur species was the primary reactive site for PAA activation, but sulfur conversion was beneficial for Fe(II) regeneration with a result of accelerated PAA activation. Unlike the homogeneous Fe<sup>2+</sup>/PAA system with organic radicals (R-O●) and ●OH as the dominant ROS, ●OH is the key reactive species in the heterogeneous FeS/PAA system for pharmaceutical degradation under various pH conditions. Interestingly and surprisingly, in-depth investigation revealed that R-O● was generated in the initial seconds of the FeS/PAA process; however, according to the standard reaction free energy calculated by the Gaussian, the formed R-O● was supposed to be quickly consumed by sulfur species, resulting in ●OH as the dominant ROS. After treatment with the FeS/PAA system, the products obtained from the three pharmaceuticals were detoxified and even facilitated the growth of <i>E. coli</i> probably due to the supply of numerous carbon sources by activated PAA. This study significantly advances the understanding of the reaction between PAA and sulfur-containing minerals and suggests the practical application potential of the FeS/PAA process combined with biotreatment processes.

Efficient activation of PAA by FeS for fast removal of pharmaceuticals: The role of sulfur in regulating the reactive oxidized species

ACS Spring 2022

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