Synthesis and Characterization of TEMPO-oxidized Cellulose Nanofibers (TCNF) and Chitosan Aerogels for the Removal of Emerging Contaminants

Abstract

This study investigates the pH-dependent self-assembly and adsorption performance of TEMPO-oxidized cellulose nanofiber (TCNF) and chitosan (CH) aerogels synthesized via air drying without chemical crosslinkers. Aerogels fabricated at pH 4 showed optimal dimensional stability due to balanced electrostatic attraction and hydrogen bonding. Varying TCNF/CH ratios at this pH revealed that the 50/50 composition achieved the highest tetracycline uptake at pH 5, driven by favorable –COO⁻/–NH₃⁺ interactions. Adsorption kinetics followed the pseudo-second-order model (R² > 0.98), while isotherm data fit both Langmuir and Freundlich models, indicating mixed monolayer–heterogeneous adsorption. FTIR confirmed hydrogen bonding, π–π stacking, and electrostatic interactions as key mechanisms. These results demonstrate that fully physical, pH-tunable TCNF/CH aerogels offer a sustainable and efficient platform for antibiotic removal from water.