Highly adsorptive removal of emerging antibiotics in water using novel Al2O3/SiO2 nanocomposites fabricated from rice husk

Abstract

Novel Al₂O₃/SiO₂ nanocomposites were successfully synthesized utilizing rice husk as a precursor. Comprehensive characterization of the Al₂O₃/SiO₂ nanocomposites was performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy-dispersive Xray spectroscopy (EDX), transmission electron microscopy (TEM), and zeta potential analysis. The nanocomposites achieved high removal efficiencies exceeding 90 % for emerging antibiotics, ciprofloxacin (CFX) and ofloxacin (OFX). Optimal conditions for CFX the removal were determined to be a pH of 7, a contact time of 90 min, and an adsorbent dosage of 10 mg/mL while for OFX the optimum paramerers were a pH of 5, a contact time of 60 min, and an adsorbent dosage of 5 mg/mL. The maximum adsorption capacities for CFX and OFX were found to be 124.8 and 22.5 mg/g, respectively. The adsorption processes for both CFX and OFX on the Al₂O₃/SiO₂ nanocomposites follow the pseudo-second-order kinetic and the Freundlich isotherm models, suggesting multilayer chemical adsorption with the interaction force mainly driven by electrostatic interactions. The Al₂O₃/SiO₂ nanocomposites exhibited reusability, retaining over 60 % removal efficiency after four reuse cycles. These results highlight the substainbility for the Al₂O₃/SiO₂ nanocomposites derived from nanosilica rice husk for the removal of antibiotics from aqueous environments.