Magnetic orange leaf biochar for favipiravir removal from wastewater

A novel magnetic biochar derived from orange leaves (MBC-OL) was developed for efficient removal of the antiviral drug Favipiravir (FVP) from wastewater. The adsorbent was synthesized through Zinc chloride/Iron (III) chloride hexahydrate (ZnCl₂/FeCl₃.6H₂O) co-activation followed by pyrolysis at 600 °C, producing a material with specific surface area of 13.31 m²/g and total pore volume of 0.103 cm³/g. Comprehensive characterization via X-ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and Energy Dispersive X-ray (SEM-EDX) confirmed successful incorporation of magnetite (Fe₃O₄) nanoparticles and abundant oxygen-containing functional groups. Response Surface Methodology (RSM) optimization identified ideal conditions (pH 8.3, adsorbent dose 0.161 g/L, contact time 97.7 min) achieving 97.5 ± 0.8% FVP removal at initial concentration of 14.1 mg/L. Kinetic studies revealed pseudo-first-order (PFO) adsorption (R²=0.917) with maximum capacity reaching 416.67 mg/g based on Langmuir isotherm. The material demonstrated exceptional stability, maintaining 93.5 ± 1.2% removal efficiency after 10 regeneration cycles. Characterization of spent adsorbent confirmed preservation of magnetic properties (52 wt% Fe retention) and structural integrity. These findings establish MBC-OL as a sustainable, high-capacity adsorbent for pharmaceutical wastewater treatment, with significant potential for agricultural waste valorization in circular economy applications.