Highly stable cellulose nanofiber/polyacrylamide aerogel via in-situ physical/chemical double crosslinking for highly efficient Cu(II) ions removal

Water pollution by heavy metal ions is a global concern due to detrimental effects on the ecological environment and human health. To solve the problem of the stability and recyclability of the traditional adsorbents, we proposed three-dimensional lamellar porous cellulose nanofiber/polyacrylamide composite aerogel with outstanding pollutants adsorption, easy regeneration, and multiple recycling. The aerogel adsorbent was prepared by a two-step method via facile in-situ physical/chemical double cross-linking and freeze-drying processes. The resulting aerogels showed good thermal stability, superior water stability and excellent adsorption properties, with a maximum Langmuir adsorption capacity for Cu(II) ions up to 240 mg g-1 due to the in-situ physical/chemical combination of anionic polyacrylamide and carbonylated cellulose nanofibers. The adsorption mechanism was the electrostatic attraction, chelating effect and complex formation driving forces for the fast and efficient adsorption of Cu(II) ions. The removal efficiency of the aerogels for Cu(II) remained above 80% after 10 adsorption/regeneration cycles, suggesting its outstanding recyclability. The proposed aerogel adsorbent shows noteworthy potential for the practical treatment of heavy metal ion wastewater.