Nanocellulose/TiO₂ composites: preparation, characterization and application in the photocatalytic degradation of a potential endocrine disruptor, mefenamic acid, in aqueous media

Nanocellulose (NC)-supported TiO₂ nanoparticles, termed NCTs, were prepared by an ultrasonic impregnation method. The as-synthesized NCTs were thoroughly characterized and studied for the photodegradation of mefenamic acid (MEF), an anthranilic acid derivative drug. The adsorption potential of NCTs increased with TiO₂ loading and 10 wt% TiO₂ NCT showed the highest sorption potential. Adsorption kinetics of MEF onto NC and NCTs indicated that the equilibrium was reached within 50 min. A pseudo-second-order model clearly represented the experimental kinetic data and demonstrated that the MEF sorption was mainly chemisorption. Equilibrium sorption analysis indicated that the adsorption followed the Langmuir model with a monolayer sorption capacity of 22.43 mg g⁻¹ for 10 wt% TiO₂ NCT. The photocatalytic degradation rates of NCTs were identical with respect to their adsorption capacities, and the apparent rate constant (k_app) values indicated that the amount of TiO₂ in NCTs played a vital role in the degradation of MEF. Furthermore, 10 wt% TiO₂ NCT showed excellent catalytic activity and reusability even after five cycles of photodegradation.