Construction of a photo-assisted peroxymonosulfate activation system comprised of iron phthalocyanine/O-doped carbon nitride for efficient tetracycline removal

The integration of peroxymonosulfate (PMS) activation and photocatalysis is an effective advanced oxidation technology for the degradation of water pollutants. In this study, iron phthalocyanine (FePc) is successfully loaded onto O-doped porous carbon nitride (OCN) forming a catalyst working in photo-assisted PMS activation. OCN is a metal-free light absorber with strong visible light absorption, while FePc could serve as a photosensitizer and PMS activator. At the same time, the construction of FePc/OCN heterojunction can form the strong internal electric field for charge migration between FePc and OCN. As a result, complete tetracycline (TC) removal within 30 min can be achieved over optimal FePc/OCN catalyst in the presence of light and PMS. Systematic controlled experiments were also carried out to reveal the effect of pH, anion, and aqueous matrix. Cyclic stability test and Fe leaching experiments indicate that the synthesized FePc/OCN is relatively stable and shows the potential in practical application. Furthermore, a comprehensive investigation was conducted on the reactive species generated during the reaction process as well as the degradation pathways of the target pollutants. This work aims to provide new insights into the design of efficient catalysts for photo-assisted PMS activation.