Bi-doped g-C3N4 for enhanced photocatalytic degradation of sulfamethoxazole under LED light: Kinetics, mechanism, and toxicity assessment

Sulfamethoxazole (SMX), a widely distributed emerging contaminant, poses significant risks to ecological systems and human health. In this work, a Bi-doped g-C 3 N 4 (Bi/g-C 3 N 4 ) photocatalyst was syntheis via calciantion using CAU-17 as the bismuth precursor, aiming to ehance SMX elimination under LED light irradiation. Among the prepared samples, 10Bi/g-C 3 N 4 exhibited the highest photocatalytic activity, achieving 99 % SMX removal within 240 min—substantially outperforming pure g-C 3 N 4 (53 %). The effects of initial pH and catalyst dosage were systematically investigated, with optimal degradation observed at pH 4.12 and a dosage of 50 mg. Radical scavenging experiments revealed that • O 2 − and • OH radicals were the primary reactive species involved in SMX degradation. Additionally, the p impact of photocatalytic treatment on plant growth was assessed using mung bean and soybean, showing minimal adverse effects. Toxicity evaluations based on QSAR modeling and seed germination assays confirmed a significant reduction in SMX toxicity after photocatalytic treatment, underscoring the environmental compatibility of the developed catalyst. • Bi-doped g-C₃N₄ was succesfully synthesized by using CAU-17 as a bismuth source. • Bi-doped g-C₃N₄ achieved 99 % SMX degradation under LED in 240 min. • Bi doping enhanced charge separation and visible light absorption. • Toxicity of SMX was reduced post-treatment, confirmed by QSAR and seeds. • Catalyst remained 85 % effective after four reuse cycles.