Results in Engineering (Dec 2024)
Enhanced photocatalytic degradation of ciprofloxacin antibiotics using Fe3O4-SiO2-EN@Zn-Al layered double hydroxide nanocomposites under the COVID-19 pandemic
Abstract
A novel layered double hydroxide nanocomposite, Fe3O4-SiO2-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 min. Comparative experiments demonstrated that incorporating Zn-Al LDH with core-shell nanoparticles (Fe3O4-SiO2-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 BOD5/COD ratio, increased from 0.28 to 0.73 after 120 min of photocatalytic oxidation under visible light, with 80.83 % COD removal and 74.17 % TOC removal. Reactive species generation, such as •OH, •O2-, 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 EC50 percentage improved from 1.27 % to 97.4 % after 4 h of CIP treatment under visible light. In conclusion, the development of the Fe3O4-SiO2-EN@Zn-Al-LDH presents a noteworthy advancement in photocatalysis for the degradation of CIP in aqueous solutions.
