Amphiprotic cellulose mediated graphene oxide magnetic aerogels for water remediation

Realizing versatile and recyclable adsorbent for removing contaminants with charge diversity from water remains challenging. Herein, amphiprotic cellulose (AP-MCC) with both cationic and anionic groups was developed to mediate self-assembled gelation of graphene oxide and Fe3O4 nanoaggregates, producing a magnetic aerogel (MAG) with opening-channels exposed with amphiprotic active groups, which exhibit ionically adsorption capability for removing both anionic and cationic contaminants including dyes and metal ions from water. The saturated adsorption capacity for Congo red and Methylene blue reaches up 282 and 346 mg g(-1), 222.2, 568.2, 185.5, and 122.2 mg g(-1) are achieved for Cu2+, Pb2+, Cd2+, and Cr3+ respectively. Adsorption kinetics of the pseudo-second-order kinetic model indicate chemisorption enabled by cationic and anionic groups dominates the adsorption process. Langmuir and Freundlich isotherm models were revealed to well depict the adsorption behaviors of MAG for metal ions and dyes, respectively. MAG after adsorption can be readily separated by magnet from water for further desorption by mild eluting, renewable MAG with stable structure and maintained adsorption capacity (> 68%) for both dyes and metal ions are demonstrated after 5 recycles. It promises a new concept for development of versatile adsorbents to address the charge diversity of pollutants.