Bamboo-derived N,Si-CQDs tailored Z-scheme BiOCl/C3N4 photocatalyst for efficient degradation of tetracycline hydrochloride and bamboo pulping effluent: Mechanism, antibacterial activity, and toxicity assessment

Biomass-derived carbon quantum dots (CQDs) offer a sustainable approach to design efficient photocatalysts due to their inherent heteroatoms and tunable surface functional groups. In this study, N and Si codoped CQDs (N,Si-CQDs) were synthesized from bamboo residues via a hydrothermal process, leveraging bamboo’s natural N and Si elements. Subsequently, Z-scheme BiOCl/N,Si-CQDs/C 3 N 4 photocatalysts were prepared, where N,Si-CQDs combine with BiOCl via Bi-O-C bonds to form atomic-scale charge-separation channels and interact with C 3 N 4 via π-π conjugation to enhance electron transfer and catalyst stability. The optimized sample (5CB-CN-10–2) exhibits TCH removal efficiency of 87.6 % at 120 min under simulated solar light irradiation, with apparent rate constant of 0.286 min −1 , which is 8.9-fold and 3.1-fold greater than those of BiOCl and BiOCl-C 3 N 4 , respectively. Notably, the catalyst sample achieves a COD removal efficiency of 81.4 % from industrial bamboo pulping effluent under conditions of 200 mg/L catalyst dosage, pH 7.5, 6 h and 40 ℃. Mechanistic investigations revealed that N,Si-CQDs acted as effective electron mediators, enhancing charge separation via Bi-O-C bonds and π-π interactions. Furthermore, the catalyst demonstrates notable antibacterial activity against Staphylococcus aureus and reduced toxicity of the degradation products. This study highlights the potential of naturally N and Si doped CQDs composite photocatalysts for environmental applications. • Bamboo was used to synthesize N,Si-CQDs with dual-doping from inherent elements. • Z-scheme BiOCl/N,Si-CQDs/C 3 N 4 composites were constructed with Bi-O-C bonds and π-π interactions for efficient charge transfer. • The 5CB-CN-10–2 catalyst achieved high photocatalytic pollutant removal. • The catalyst exhibited strong antibacterial activity against S . aureus .