EFFECTIVENESS ADSORPTION EFFECTIVENESS OF ENROFLOXACIN ANTIBIOTIC WASTE USING KOH ACTIVATED (CEIBA PENTANDRA) HULL HYDROCHAR

Abstract

ABSTRACT

Environmental contamination by the antibiotic enrofloxacin has become an increasing concern due to its extensive use in veterinary medicine and the limited capability of conventional wastewater treatment processes to remove it effectively. This study investigated the adsorption performance of KOH-activated hydrochar derived from kapok peel (Ceiba pentandra) for the removal of enrofloxacin from aqueous solutions. The effects of particle size (120, 140, and 160 mesh), adsorbent dosage (0.5–2.5 g L⁻¹), initial enrofloxacin concentration (5–20 mg L⁻¹), solution pH (3–11), water matrix (deionized water, rainwater, and river water), and adsorption kinetics were systematically evaluated. The optimum adsorption performance was achieved using 120-mesh hydrochar, an adsorbent dosage of 2.5 g L⁻¹, an initial enrofloxacin concentration of 5 mg L⁻¹, pH 7, and deionized water, yielding removal efficiencies of 37.3%, 65%, 64%, 73%, and 63%, respectively. Kinetic analysis demonstrated that the adsorption process was better described by the pseudo-second-order model (R² = 0.999, qₑ = 2.33 mg g⁻¹) than by the pseudo-first-order model (R² = 0.969), indicating that chemisorption was the dominant adsorption mechanism. FTIR characterization confirmed the presence of hydroxyl (–OH), ether (C–O–C), and aromatic (C=C) functional groups on the hydrochar surface, which facilitated hydrogen bonding and π–π interactions with enrofloxacin molecules. These findings demonstrate that KOH-activated kapok peel-derived hydrochar is a promising, sustainable, and cost-effective adsorbent for the removal of fluoroquinolone antibiotic residues from contaminated water.