Assessment of Biochar from Tomato Waste Modified by Acid Activation and FeO Modification for Ciprofloxacin Removal from Wastewater

Biochar, due to its specific properties, can adsorb organic pollutants from the environment. To improve the adsorption performance of biochar, it is important to modify it. In this work, activated biochar (Bch-HCl) and magnetic biochar (Bch-HCl-Fe3O4) were characterized via transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) techniques. The materials were evaluated for their efficacy in removing ciprofloxacin (CIP) from aqueous solution. The effects of adsorbent dose, contact time, temperature, and pollutant concentration were examined. The best removal degree of CIP for both adsorbents was obtained for an initial concentration of 5 mg L-1, adsorbent dose of 5 g L-1, 20 min, and 25 degrees C. The equilibrium data were best described by the Langmuir isotherm model for both adsorbents, with a maximum adsorption capacity of 2.04 mg g-1 for Bch-HCl and 4.14 mg g-1 for Bch-HCl-Fe3O4. Moreover, the adsorption process best fit with the pseudo-second-order model kinetics, and the thermodynamic analysis indicated a spontaneous and endothermic process for Bch-HCl and a spontaneous and exothermic process for Bch-HCl-Fe3O4.