Mohammadjavad Jahanshahi

Pharmaceutical pollutants such as nitrofuran antibiotics are emerging contaminants that threaten aquatic ecosystems and human health due to their persistence and toxicity. This study valorized apple peel waste as a renewable carbon source to synthesize sulfur and nitrogen co-doped carbon quantum dots (S,N-CQDs) via a green route, reducing energy demand and cost. An S-C₃N₄/MnFe₂O₄-S,N-CQDs heterostructure was subsequently fabricated and applied for photocatalytic degradation of furazolidone (FZD). The integration of sulfur-doped graphitic carbon nitride, MnFe₂O₄ magnetic nanoparticles, and S,N-CQDs produced a synergistic effect by enhancing visible-light harvesting, suppressing electron–hole recombination, and improving charge transfer. Comprehensive analyses (FTIR, XRD, UV–Vis DRS, VSM, FESEM, TEM, and Mott–Schottky) confirmed the structural integrity of the composite. The incorporation of MnFe₂O₄ imparted magnetic properties, facilitating easy recovery and reuse of the catalyst with stable performance over five consecutive cycles. Optimization of operating parameters (pH, catalyst dosage, irradiation time, and pollutant concentration) enabled 96.8 % FZD removal within 90 min of visible-light irradiation. Moreover, photocatalytic treatment significantly reduced FZD toxicity, as validated by enhanced lentil seed germination and plant growth in treated wastewater compared with untreated effluent. Overall, this study demonstrates a sustainable strategy that couples agro-waste valorization with advanced photocatalysis, providing a replicable and eco-friendly approach for antibiotic removal from wastewater.