Ultra efficient removal of heavy-metal ions and dyes using a novel cellulose-based three-dimensional network

Cellulose-based adsorbents have attracted extensive attention owing to their ecofriendly characteristics. However, most cellulose-based adsorbents possess inadequate adsorption capabilities for typical pollutants such as heavy-metal ions and dyes. Herein, we developed a cost-effective and robust cellulose-based adsorbent with a three-dimensional network structure based on hydrogen bonds and electrostatic interactions via the simple supramolecular self-assembly of carboxymethyl cellulose (CMC), cationic polyacrylamide (CPAM), and tannic acid (TA) (referred to as CMC–CPAM–TA). Benefiting from the abundant catechol/carboxyl groups and mesoporous/macroporous channels, CMC–CPAM–TA could trap Cu(II) ions and rhodamine B (RhB) (representing a typical heavy-metal ion and dye, respectively) by rapidly forming Cu–O coordination bonds and inducing electrostatic interactions. CMC–CPAM–TA exhibited high adsorption capacities for Cu(II) ions and RhB, which were 669.8 and 202.2 mg/g, respectively. These values are 1.3–23.6 and 1.1–72.2 times higher than those of commonly reported cellulose-based adsorbents, respectively. Furthermore, CMC–CPAM–TA showed high regenerative ability for Cu(II) ions and RhB after five cycles owing to its robust structure.