Solar-initiated continuous electron injection to promote Fe3+/Fe2+ catalytic cycle in tourmaline/g-C3N4 composite system for enhanced PMS activation

It is of great significance for improving the electron transmission performance of graphite phase carbon nitride (gC(3)N(4)) by an economical method. Herein, urea was mixed with tourmaline (TM) and calcined to obtain g-C3N4/TM composite photocatalyst. Under solar light, g-C3N4/TM activated peroxymonosulfate (PMS) to degrade carbamazepine (CBZ) entirely within 25 min. g-C3N4/TM had a superior photocatalytic oxidation performance under solar light than g-C3N4. Photogenerated electron-hole pairs of g-C3N4 were efficaciously suppressed, originating from the more excellent electronic transfer to TM. Four active species, including SO4 center dot(-), center dot OH, O-1(2), and O-2 center dot(-), were identified for the degradation of CBZ. Ten intermediates of CBZ and six intermediates of sulfaquinoxaline sodium (SQXNa) were determined by using ultra-performance liquid chromatography coupled with a high definition mass spectrometer (UPLC-HDMS), and a degradation pathway was proposed. As the reaction progressed, all aromatic nuclear intermediates were mineralized. The degradation of other organic pollutants by the g-C3N4/TM/PMS system validated the universal adaptability in practical applications. This research provided an effective way to improve the g-C3N4 photocatalytic activity in wastewater treatment.