Aqueous‐Phase Surface Amidation of TEMPO‐CNF Films for Improved Adsorption of Organic Pollutants in Water

Wastewater treatment remains a critical global issue due to the release of hazardous chemicals that pose environmental and health risks. This study presents the first preparation of highly efficient and recyclable TEMPO-oxidized cellulose nanofiber (TEMPO-CNF) films, surface-grafted through a novel and straightforward method for water decontamination. The films are modified via immersion in an aqueous solution of benzylamine and DMTMM, yielding TEMPO-CNF-g-BnNH₂ materials. Characterization by atomic force microscopy, attenuated total reflectance Fourier trasnsform infrared spectroscopy, X-ray photoelectron spectroscopy, elemental analysis, and water-resistance testing confirmed successful grafting. This functionalization enhanced material properties, improving water stability by 81% and reducing water uptake by 88%. Contact angle measurements, surface plasmon resonance analysis, and kinetic and thermodynamic studies indicate that the introduction of benzylamine modifies surface hydrophobicity and increases chemical affinity with organic pollutants. While π-π interactions may play a role, especially with aromatic contaminants, the sorption behavior is overall influenced by a combination of hydrophobic effects and increased molecular similarity with the target molecules. The grafted films demonstrated high adsorption capacities for methylene blue and chlorhexidine (163.9 and 217.4 mg g^-1, respectively), along with excellent reusability and washability. Biodegradability tests confirmed complete degradation within 90 days. This work offers a sustainable strategy for producing advanced cellulose-based adsorbents for efficient and ecofriendly wastewater treatment.