Adsorption of small size microplastics based on cellulose nanofiber aerogel modified by quaternary ammonium salt in water

[Display omitted] •Aerogels were prepared by directional freezing, and porous biomimetic structures were given by the directional growth of ice crystals.•The aerogel was modified by quaternary ammonium salt and applied to remove microplastics.•The aerogel showed high adsorption capacity of 146.38mg/g for microplastics.•The adsorption process of microplastics was showed by fluorescence characteristics. Due to severe water pollution and water shortage, research on biomass adsorbent materials with high adsorption capacity for microplastics in water is one of the effective methods to control and solve water pollution. In this paper, cellulose nanofibers (CNF) were selected as the matrix material, 2, 3-epoxypropyl trimethyl ammonium chloride (EPTMAC) as a modifier, and polyvinyl alcohol (PVA) as a crosslinking agent were used to prepare the modified cellulose nanofibers aerogel with directional structure by liquid nitrogen freezing method, which was used for the adsorption of small size microplastics in water. The modified aerogel has a good adsorption capacity of 146.38 mg/g for small size microplastics, and the adsorption behavior of aerogel conforms to Langmuir isotherm and pseudo-first-order and pseudo-second-order adsorption kinetics model. Meanwhile, the fluorescence characteristics show that the adsorption behavior occurred. In addition, the modified aerogel still maintains good adsorption capacity under different influence factors. Therefore, modified cellulose nanofibers aerogel has a broad application prospect in the field of removing microplastics from water.