Synergistic multiple active species for the photocatalytic degradation of contaminants by imidazole-modified g-C3N4 coordination with iron phthalocyanine in the presence of peroxymonosulfate

Abstract

Utilizing peroxymonosulfate (PMS)-based advanced oxidation processes to remove emerging contaminants in water has received widespread attention. In this study, g-C3N4-IMA-FePcCl16 that was fabricated by axial coordination was applied to activate PMS for carbamazepine (CBZ) degradation. The introduction of imidazole-based ligand (IMA) and iron hexadecachlorophthalocyanine (FePcCl16) facilitates the photogenerated electron-hole pairs separation of g-C3N4 and broadens the visible-light response range. The coordination structure was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. Photocatalytic experiments demonstrated that g-C3N4-IMA-FePcCl16 can highly effective eliminate CBZ with a removal of ∼95% within 25 min in the presence of PMS. The effects of various experimental parameters on the CBZ degradation were investigated, such as the loading amount of FePcCl16, pH, PMS dosage and anions. It is noteworthy that Cl− has a positive effect on the degradation of CBZ. Another interesting finding is that the degradation of CBZ is attributed to the synergistic effect of multiple active species, which is confirmed by gas chromatography-mass spectrometry, electron paramagnetic resonance and radical quenching tests. Superoxide radicals (O2−) and singlet oxygen (1O2) are the dominated active species. This work offers a novel idea for the rational design of high-efficiency photocatalysts for wastewater remediation.