Nanocellulose/UiO-66-NH₂ Nanocomposite for Efficient Removal of Tetracycline and Ciprofloxacin from Aqueous Solutions

Abstract

The increasing occurrence of antibiotic residues in aquatic environments has become a major environmental concern due to their persistence, ecological toxicity, and contribution to the development of antibiotic-resistant bacteria. In the present study, a nanocellulose/UiO-66-NH₂ nanocomposite was synthesized and evaluated as an efficient adsorbent for the removal of tetracycline (TC) and ciprofloxacin (CIP) from aqueous solutions. The physicochemical properties of the synthesized nanocomposite were characterized using dynamic light scattering (DLS), zeta potential analysis, and Brunauer–Emmett–Teller (BET) surface area analysis. The synthesized nanocomposite exhibited an average hydrodynamic particle size of approximately 165 nm, a zeta potential of −31.8 mV, and a BET surface area of approximately 620 m²/g, indicating good colloidal stability and a well-developed mesoporous structure. Batch adsorption experiments were performed to investigate the effects of solution pH, contact time, and initial antibiotic concentration on adsorption performance. Maximum adsorption efficiency was achieved at pH 7, while adsorption equilibrium was reached within approximately 90 min for both antibiotics. The equilibrium data were better described by the Langmuir isotherm model than by the Freundlich model, indicating predominantly monolayer adsorption. The maximum adsorption capacities obtained from the Langmuir model were 286.4 mg/g for tetracycline and 254.7 mg/g for ciprofloxacin. The excellent adsorption performance of the synthesized nanocomposite was attributed to the synergistic effects of electrostatic attraction, hydrogen bonding, π–π interactions, pore filling, and coordination interactions between antibiotic molecules and the functional groups of the nanocellulose/UiO-66-NH₂ framework. Furthermore, the adsorbent maintained more than 90% of its initial removal efficiency after five consecutive adsorption–desorption cycles, demonstrating excellent reusability. These findings suggest that the synthesized nanocellulose/UiO-66-NH₂ nanocomposite is a promising, environmentally friendly, and highly efficient adsorbent for the removal of antibiotic contaminants from aqueous environments.