Preparation and Characterization of Anion-Capturing Aerogel from Freeze-Dried Quaternary Ammonium Cellulose Nanofibers

Cellulose nanofibers (CNFs) are natural nanomaterials derived from cellulose with tunable surface properties, making them ideal candidates for water filtration applications.By adjusting the width and length of these fibers, the pore size of filters can be controlled.In this study, CNFs were functionalized with quaternary ammonium groups via a pre-treatment process to enhance their anion capture efficiency.The degree of quaternary amination was varied to systematically tune the charge density and anion adsorption capacity of the CNFs.Cellulose treated with different amounts of glycidyltrimethylammonium chloride (GMA) was processed through a high-pressure homogenizer to produce CNFs with quaternary ammonium groups.The properties of the functionalized CNFs, including zeta potential, particle size distribution, and viscosity, were analyzed.Zeta potential analysis revealed that increasing the degree of quaternary amination reduced the anionic nature of the fibers and confirmed substitution with cationic quaternary ammonium groups.Furthermore, higher degrees of amination resulted in shorter fibers and enhanced intermolecular interactions, leading to increased viscosity.The CNFs were processed into aerogels and evaluated for anion adsorption capacity.Energy-dispersive X-ray spectroscopy (EDS) demonstrated a higher distribution of nitrogen on the CNF surface with increased amination.Filters produced with these CNFs captured more Cl -and Br -ions from 500 ppm solutions, while effectively reducing the charge density of the filtered solutions.These findings demonstrate the potential of functionalized CNFs as sustainable and efficient materials for advanced water filtration systems.The results underscore the importance of tailoring surface functionalization to optimize performance in anion removal, highlighting applications in industrial and municipal wastewater treatment.