Shape memory aerogels from nanocellulose and polyethyleneimine as a novel adsorbent for removal of Cu(II) and Pb(II)

This study describes the preparation of an aerogel adsorbent based on nanofibrillated cellulose(NFC) and polyethyleneimine(PEI) via electrostatic combination without chemical crosslinking. Purely physical crosslinking between NFC and PEI was confirmed by attenuated total refraction-Fourier transform infrared spectroscopy (ATR-FTIR) and thermogravimetric analysis (TGA). The NFC/PEI hybrid aerogels exhibited good structural stability and shape recovery in water. Absorption experiment shows that the hybrid aerogels are excellent adsorbents for the removal of heavy metal ions owing to the highly porous structure and the existence of plenty of amine groups. Thermodynamic and kinetic study showed pseudo-second-order equation and Langmuir model (R2 > 0.999) as the best fit. The maximum adsorption capacity of Cu(II) and Pb(II) according to Langmuir model was 175.44 mg/g and 357.44 mg/g, respectively. Besides, the Cu(II) or Pb(II) loaded NFC/PEI aerogel could be easily regenerated by EDTA and retain the adsorption capacity after repeatedly using. This environmentally friendly hybrid aerogels with high-performance are promising candidates for sewage disposal and metal pollution treatment.