Homojunction of graphitic carbon nitride for efficacious chlortetracycline degradation via peroxydisulfate activation

Environmental water systems are endangered by antibiotics owing to their persistence and antimicrobial resistance properties. In this study, a novel homojunction photocatalyst composed of EDTA-modified and pristine graphitic carbon nitride (eGCN/pGCN) was developed to facilitate the enhancement of charge carrier separation and visible light absorption for the degradation of chlortetracycline hydrochloride (CTCH). Characterization results confirmed the successful synthesis of a homo-structured photocatalyst with enhanced structural stability and interfacial charge transfer. The charge carriers underwent a direct Z/S-scheme transfer pathway, which enhanced the photocatalytic activity, inferred from the combined Mott-Schottky plots, UV-Vis DRS, XPS binding energy shifts, and scavenger experiments. The homojunction exhibited 85% efficiency with a kinetic constant of 0.013941 min -1 in CTCH degradation within 120 min. The degradation efficiency improved to 96% within 30 min upon addition of peroxydisulfate (PDS) as an external oxidant, confirming the synergy between the photocatalyst and sulfate radicals. The catalyst showed a degradation efficiency of 91% with a kinetic constant of 0.7842 min -1 in real water samples. Reusability studies resulted in degradation efficiency above 90% after five consecutive cycles, which confirmed the high stability of the homojunction photocatalyst. Overall, this work demonstrates the potential application of metal-free g-C 3 N 4 homojunction for pharmaceutical remediation in wastewater.