Mechanistic and practical insights into tetracycline degradation via 2D/2D N-doped biochar/carbon nitride-driven peroxymonosulfate activation: Toxicity mitigation and product analysis.

In this study, a rationally designed 2D/2D composite from N-doped biochar (NC) and S-doped graphitic carbon nitride (CNS) was developed for efficient peroxymonosulfate (PMS) activation toward tetracycline (TC) degradation. Peanut shell-derived NC produced via urea treatment showed both excellent conductivity and an advantageous 2D structural configuration. The strategic incorporation of NC within the CNS matrix to engineer 2D/2D architectures significantly enhances interfacial contact while establishing efficient electron transport pathways, thereby optimizing charge carrier dynamics through improved mobility and separation efficiency. When combined with PMS to construct an advanced oxidation system, the 2D/2D NC-CNS3 composite achieved 89.5 % degradation rate of TC under optimal conditions within 70 min-twice that of original sample CNS-featuring a reaction k roughly 4.5-fold higher (938.7 × 10 min). Liquid chromatography-mass spectrometry was employed to elucidate the possible intermediates formed during TC degradation, while the ecotoxicological profiles of these transformation products underwent assessment using quantitative structure-activity relationship modeling approaches. Meanwhile, economic analysis demonstrates the strong commercial viability of the 2D/2D NC-CNS3 photocatalyst. This work advances the mechanistic investigation of biochar in wastewater treatment via advanced oxidation processes, while offering novel perspectives for developing eco-friendly and sustainable wastewater treatment systems.