Enhanced photocatalytic degradation of ciprofloxacin antibiotics using Fe3O4-SiO2-EN@Zn-Al layered double hydroxide nanocomposites under the COVID-19 pandemic

• Fe 3 O 4 -SiO 2 -EN@Zn-Al-LDH as a novel photocatalyst for ciprofloxacin degradation. • Characterization analysis confirms successful synthesis with impressive properties. • Integration of Zn-Al LDH with core-shell nanoparticles boosts removal efficiency by 2.5-6 times. • Fe 3 O 4 -SiO 2 -EN@Zn-Al-LDH showed a maximum degradation efficiency of 100%. • The Fe 3 O 4 -SiO 2 -EN@Zn-Al-LDH showed good photocatalytic activity for five cycles. • Degradation under UV, visible, and solar radiation, was excellent. A novel layered double hydroxide nanocomposite, Fe 3 O 4 -SiO 2 -EN@Zn-Al-LDH, was synthesized and employed as a photocatalyst for the degradation of ciprofloxacin (CIP) in aqueous solutions. Characterization of the photocatalyst was performed using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) techniques. The results indicated successful synthesis of particle with specific surface area of 28.67 m²/g, pore size of 1.64 nm, and pore volume of 6.58 cm³/g. Optimal degradation of CIP was observed under the following conditions: pH 5, photocatalyst dosage of 0.6 g/L, initial CIP concentration of 25 mg/L, and an irradiation duration of 60 minutes. Comparative experiments demonstrated that incorporating Zn-Al LDH with core-shell nanoparticles (Fe 3 O 4 -SiO 2 -EN) enhanced removal efficiency by 2.5 to 6 times compared to individual materials. The composite exhibited efficient activation under UV, visible light, and solar radiation, resulting in 100% degradation of CIP under UV, 100% under visible light, and 81.4% under solar radiation. Biodegradability, indicated by the BOD 5 /COD ratio, increased from 0.28 to 0.73 after 120 minutes of photocatalytic oxidation under visible light, with 80.83% COD removal and 74.17% TOC removal. Reactive species generation, such as • OH, • O 2 - , and h + , was confirmed by introducing scavengers (TBA, BQ, and TEOS) into the reaction medium. The photocatalytic activity of the nanocomposite was slightly decreased over 5 consecutive CIP treatment cycles. Toxicity assessment of treated wastewater using E. coli and Daphnia magna bioassays revealed a significant decrease in E. coli growth inhibition rate with prolonged treatment time. The EC 50 percentage improved from 1.27% to 97.4% after 4 hours of CIP treatment under visible light. In conclusion, the development of the Fe 3 O 4 -SiO 2 -EN@Zn-Al-LDH presents a noteworthy advancement in photocatalysis for the degradation of CIP in aqueous solutions.