Preparation of mussel-inspired polydopamine-functionalized TEMPO-oxidized cellulose nanofiber-based composite aerogel as reusable adsorbent for water treatment

Abstract

Water pollution is an ongoing trouble that is of significant urgency to resolve worldwide. However, traditional materials used in the process of water purification are costly and energy intensive. The preparation of low-cost, green and sustainable aerogels with low density, high porosity and high specific surface area (SSA) is a great challenge. In this paper, a mussel-inspired, low-cost, polydopamine (PDA)-functionalized TEMPO-oxidized cellulose nanofiber (TOCNF) PDA/TOCNF composite aerogel has been rationally designed and fabricated with low-density, high porosity and high SSA. The PDA/TOCNF composite aerogel shows low density (18.2 mg/cm3), high porosity (98.7 %), and large surface areas (41.3 m2/g). The resulting PDA/TOCNF composite aerogel could adsorb a maximum of 314.6 mg/g of methylene blue (MB). The recycle experiment for reusing of adsorbent showed that after five consecutive cycles, the removal ability of MB by the PDA/TOCNF composite aerogel still maintained higher than 90 %. In addition, the PDA/TOCNF composite aerogel also had a high adsorption capacity of heavy metal ions, for example, it adsorbs 446.0 mg/g of Cu2+, 222.0 mg/g of Pb2+, 267.0 mg/g of Cd2+, and 600.0 mg/g of Fe3+, respectively. The possible adsorption mechanisms imply that the PDA/TOCNF composite aerogel adsorbs MB due to the synergistic binding interactions, such as electrostatic attraction, π-π stacking interaction, Vander waals force, and hydrogen bonding. Similarly, the PDA/TOCNF composite aerogel adsorbs metal ions due to the electrostatic attraction and chelation of metal ions with the PDA/TOCNF aerogel. Therefore, PDA/TOCNF composite aerogels may have potential applications in wastewater treatment because of their sustainability and low energy consumption.