This study presents the green synthesis and characterization of a novel Fe3O4/Biochar/Ag photocatalyst aimed at effectively degrading the antibiotic pollutants tetracycline and enrofloxacin. The synthesis process began with the preparation of biochar from corn kernels, followed by the immobilization of Fe3O4 nanoparticles on its surface. Silver nanoparticles were then synthesized using corn silk extract and incorporated into the Fe3O4/Biochar composite. To gain insights into the physical and optical properties of the synthesized photocatalyst, various characterization techniques were employed. Brunauer–Emmett–Teller (BET) analysis revealed a surface area of 71.6 m2/g, indicating a high potential for catalytic activity. Barrett-Joyner-Halenda (BJH) analysis determined an average pore diameter of 9.97 nm, suggesting a favorable porous structure for enhanced mass transfer. Diffuse Reflectance Spectroscopy (DRS) measurements indicated a bandgap energy of 2.4 eV, suitable for efficient light absorption and subsequent photocatalytic reactions. Additional characterization methods included Infrared Spectroscopy (FTIR), Vibrating Sample Magnetometer (VSM), X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES).The photocatalytic activity was evaluated under visible light irradiation, achieving remarkable degradation efficiencies of 96% for both tetracycline and enrofloxacin within 50 min and 70 min, respectively, under optimized conditions of neutral pH (7) and catalyst dosages of 10 mg for tetracycline and 15 mg for enrofloxacin. Kinetic studies revealed that the degradation followed pseudo-first-order kinetics, with apparent rate constants (kapp) of 0.063 min−1 for tetracycline and 0.043 min−1 for enrofloxacin, confirmed by high correlation coefficients (R2 values of 0.9884 and 0.983, respectively). The photocatalyst also demonstrated excellent stability and reusability, maintaining over 82% efficiency after three consecutive cycles. Furthermore, the study investigated the effects of various parameters such as pH and photocatalyst dosage on degradation efficiency, establishing that optimal conditions significantly enhance performance. Overall, this research highlights the potential of the synthesized Fe3O4/Biochar/Ag photocatalyst as a sustainable solution for removing antibiotic contaminants from water bodies.

Green synthesis of silver nanoparticles and their immobilization on magnetic biochar for the removal of tetracycline and enrofloxacin

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发表日期：

2025年1月30日

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Fatemeh Sadat Safavi,
S. Yousef Ebrahimipour,
S. Jamilaldin Fatemi,
Pourya Mohammadi,
Tayebeh Shamspur

摘要

This study presents the green synthesis and characterization of a novel Fe₃O₄/Biochar/Ag photocatalyst aimed at effectively degrading the antibiotic pollutants tetracycline and enrofloxacin. The synthesis process began with the preparation of biochar from corn kernels, followed by the immobilization of Fe₃O₄ nanoparticles on its surface. Silver nanoparticles were then synthesized using corn silk extract and incorporated into the Fe₃O₄/Biochar composite. To gain insights into the physical and optical properties of the synthesized photocatalyst, various characterization techniques were employed. Brunauer–Emmett–Teller (BET) analysis revealed a surface area of 71.6 m²/g, indicating a high potential for catalytic activity. Barrett-Joyner-Halenda (BJH) analysis determined an average pore diameter of 9.97 nm, suggesting a favorable porous structure for enhanced mass transfer. Diffuse Reflectance Spectroscopy (DRS) measurements indicated a bandgap energy of 2.4 eV, suitable for efficient light absorption and subsequent photocatalytic reactions. Additional characterization methods included Infrared Spectroscopy (FTIR), Vibrating Sample Magnetometer (VSM), X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES).The photocatalytic activity was evaluated under visible light irradiation, achieving remarkable degradation efficiencies of 96% for both tetracycline and enrofloxacin within 50 min and 70 min, respectively, under optimized conditions of neutral pH (7) and catalyst dosages of 10 mg for tetracycline and 15 mg for enrofloxacin. Kinetic studies revealed that the degradation followed pseudo-first-order kinetics, with apparent rate constants (k_app) of 0.063 min⁻¹ for tetracycline and 0.043 min⁻¹ for enrofloxacin, confirmed by high correlation coefficients (R² values of 0.9884 and 0.983, respectively). The photocatalyst also demonstrated excellent stability and reusability, maintaining over 82% efficiency after three consecutive cycles. Furthermore, the study investigated the effects of various parameters such as pH and photocatalyst dosage on degradation efficiency, establishing that optimal conditions significantly enhance performance. Overall, this research highlights the potential of the synthesized Fe₃O₄/Biochar/Ag photocatalyst as a sustainable solution for removing antibiotic contaminants from water bodies.