Binding Fe-doped g-C3N4 on the porous diatomite for efficient degradation of tetracycline via photo-Fenton process

We fabricated iron-doped carbon nitride on a diatomite surface through a single-step polymerization (FGD-x, where x represents Fe loading content). The FGD-x efficiently degrades tetracycline hydrochloride by a collaborative photo-Fenton process. The FGD-3 (FeCl3 loading 75 mg) showed the best catalytic performance in TC degradation with minimal H2O2 (viz. 1 mmol/L) at a wide pH range (2.0–7.0). Under optimized conditions, the FGD-3 can degrade 98.3% of 20.0 mg/L TC at pH 4.0 within 100 min under visible light irradiation. The scanning electron microscopic and X-ray photon spectroscopic data show that iron is successfully doped on g-C3N4. Electrochemical impedance spectroscopy and transient photocurrent performance analyses confirmed that photogenerated electrons rapidly transfer at FGD-3 and solution interface. Free radical quenching experiments and electron spin resonance analysis show that h+, ∙O2-, and ∙OH can degrade TC efficiently. Besides, FGD-3 has an ultra-high catalytic activity and extremely low iron leaching after repeated use. The FGD-3 provides a feasible way to design a new photo-Fenton catalyst for the destruction of organic pollutants from water.