Visible-light-assisted peroxymonosulfate activation and mechanism for the degradation of pharmaceuticals over pyridyl-functionalized graphitic carbon nitride coordinated with iron phthalocyanine

Recently, peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) have received increasing attention because of their capability and adaptability in decontamination. The couple of solar light and PMS activation is an environmentally friendly and efficient strategy for environmental remediation. Herein, the iron hexadecachlorophthalocyanine (FePcCl 16 ) was used to coordinate with graphitic carbon nitride (g-C 3 N 4 ), which was functionalized by pyridine-based ligand isonicotinic acid (INA) to prepare a distinctive catalyst, g-C 3 N 4 -INA-FePcCl 16 . The experimental results revealed that g-C 3 N 4 -INA-FePcCl 16 can activate PMS efficiently for the elimination of carbamazepine (CBZ) under visible light irradiation over a wide pH range. Upon irradiation with visible light, CBZ was destroyed by the solider g-C 3 N 4 with generated sulfate (SO 4 − ) and hydroxyl ( OH) radicals, on the other hand, high-valent iron (Fe (IV)   =   O) species accompanied by SO 4 − and OH radicals were produced by excited-state FePcCl 16 (*FePcCl 16 ) during oxidation, which is different from a traditional PMS activation system. The axial pyridine-based ligand was protected under the FePcCl 16 macrocyclic structure shield. Noteworthy, in the absence of visible light, g-C 3 N 4 -INA-FePcCl 16 showed a higher catalytic performance than pure g-C 3 N 4 , FePcCl 16 and a mechanical mixture of the two. This study allows for the construction of an effective and environmental catalytic system, which can be applied to purify water that contains refractory pollutants.