Engineering sodium alginate-based cross-linked beads with high removal ability of toxic metal ions and cationic dyes.

Sodium alginate (SA) beads with ultrahigh adsorption capacity were prepared via hydrogen bonds between SA and 2-acrylamido-2-methylpropa-1-propanesulfonic acid (AMPS), and the AMPS was then post-cross-linked to manufacture SA/PAMPS beads. The equilibrium adsorption capacities of methylene blue (MB) and Pb for the SA/PAMPS10 beads were 2977 and 2042 mg/g, respectively. Although the SA beads exhibited higher equilibrium adsorption capacities of MB and Pb than those of the SA/PAMPS10 beads, the SA/PAMPS10 beads had better mechanical property and higher stability. The pseudo-second-order kinetic model and the Langmuir isotherm described the adsorption processes of the SA/PAMPS10 beads for MB well. In addition, the SA/PAMPS10 beads could be reused with stable adsorption capacity for at least three cycles. The beads also had excellent performances on absorbing methylene violet and other heavy metal ions (Cu, Cd and Ni). Therefore, the SA-based beads with high adsorption capacity might be good candidates for industrial pollutant treatments.