Carbon nitride-type polymers compounded with FeOCl to enhance the catalytic removal of antibiotics over a wide pH range: Performance and mechanism

The ubiquity of antibiotics challenges water treatment and public health. Herein, a novel heterogeneous Fenton system was constructed to remove antibiotics, and carbon nitride-type polymers compounded with FeOCl (CNPs/FeOCl) were used as catalysts. The efficiency for removal of tetracycline hydrochloride (TC-HCl) reached 100 % within 6 min ([TC-HCl] = 20 mg/L, [CNPs/FeOCl] = 0.2 g/L, [H2O2] = 0.3 mM, pH = 3.5), and the catalytic activity of CNPs/FeOCl was higher than those of FeOCl and CNPs alone. In particular, the TC-HCl degradation efficiencies over a wide pH range of 3 to 11 were nearly 100 % within 8 min. TC-HCl and its oxidation intermediates were degraded by the ·OH radicals produced from Fe2+/Fe3+ induced degradation of H2O2, and small molecules (H2O and CO2) were eventually produced, which enabled antibiotic degradation through three possible pathways. Additional results showed that electrons promoted the cycling of Fe2+ and Fe3+ from the FeOCl, which enhanced the decomposition of H2O2 to produce more ·OH and improve the catalytic activity. Finally, the novel Fenton system catalyzed efficient degradations of antibiotics in natural water, providing a potential method for removal of antibiotics and other organic pollutants with CNPs/FeOCl.