Abstract:

The growing problem of water pollution has created an urgent need to develop efficient and sustainable methods for pollutant removal. This study proposes the preparation of a cellulose-based aerogel with high adsorption capacity of both anionic and cationic pollutants by an atmospheric pressure drying method. Firstly, polyethyleneimine (PEI) was attached to carboxymethylated cellulose nanofibre (CNF) backbone through electrostatic interactions, and then chemical cross-linking using γ-aminopropyltriethoxysilane (APTES) and glutaraldehyde (GA) was used to obtain the CNF/PEI hydrogel, and finally an aerogel with high porosity (92.06%) and low density (18.80 mg/cm³) was prepared by solvent exchange and atmospheric pressure drying method. This aerogel showed an excellent structural stability in water. Benefitting from the presence of both anionic carboxymethyl and cationic amino groups, the aerogel was able to adsorb both cationic and anionic dyes in complex wastewater environments. The maximum adsorption capacity of the aerogel for methylene blue (MB) and congo red (CR) was 516 mg/g and 2090 mg/g, respectively, and the removal rate of anionic and cationic dyes reached more than 98%. In addition, aerogel showed good structural stability and anti-fatigue properties. It remained intact after one week of immersion in alkaline solution, and its elastic recovery rate remained at 60% after 10 cycles of compression in the wet state. Compared with similar adsorbent materials, CPA has significant advantages in terms of adsorption capacity, amphiphilic adsorption capacity and reusability. The preparation method proposed in this study exhibited short consuming time  and high efficiency, which is suitable for large-scale production and is expected to be applied in industrial wastewater treatment.

Key words: nanocellulose, aerogel, surface modification, dye adsorption, water treatment technology