Adsorptive Removal of Emerging Antibiotic Contaminants from Aquatic Environments Using Magnetically Modified Biochar

The widespread presence of pharmaceutical residues, particularly emerging antibiotics such as levofloxacin (LVX) and amoxicillin (AMOX), in aquatic environments poses serious risks to ecosystems and public health. In this study, magnetically modified biochar was synthesized from orange peel waste and evaluated for the percentage removal of LVX and AMOX from synthetic wastewater. The biochar was chemically modified with iron to enhance its adsorption capacity and facilitate magnetic separation. The physicochemical properties of raw and iron-modified biochar were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). Batch adsorption experiments were conducted to investigate the effects of temperature, contact time, adsorbent dosage, pH, and initial antibiotic concentration on removal efficiency. Antibiotic concentrations were quantified using UV–Vis spectrophotometry. Batch adsorption experiments revealed that iron-modified biochar (FeMBC) significantly outperformed raw biochar (RBC) in antibiotic removal. Optimal removal efficiencies of 90% for AMOX and 92% for LVX were achieved at an adsorbent dosage of 0.1 g, antibiotic concentration of 10 mg L−1, contact time of 120 min, and temperature of 30 °C. Equilibrium data were best described by the Langmuir isotherm model, indicating monolayer adsorption, with correlation coefficients of 0.98 for AMOX and 0.97 for LVX. Kinetic analysis showed that the pseudo-second-order model provided the best fit, suggesting that chemisorption dominated the adsorption process. Thermodynamic studies confirmed that the adsorption was spontaneous and exothermic. Overall, the results demonstrate that iron-modified orange peel biochar is an efficient (90% better removal efficiency than RBC), low-cost, and environmentally sustainable adsorbent for the removal of emerging antibiotics from pharmaceutical wastewater, offering strong potential for practical water treatment applications.