Collagen/cellulose hydrogel beads reconstituted from ionic liquid solution for Cu(II) adsorption

- Collagen/cellulose hydrogel beads (CCHBs) reconstituted from a [C4mim]Cl solution.
- Cu(II) adsorption steeply increases until collagen/cellulose mass ratio exceeds 2/1.
- The CCHBs have good adsorption properties and reusability.