A nanoporous hydrogel based on vinyl-functionalized alginate for efficient absorption and removal of Pb2+ ions

Vinyl-functionalized sodium alginate (VSA) was used as matrix and crosslinker to fabricate VSA-co-methylacrylic acid-co-italic acid (VSA-co-MAA-co-IA) nano-porous hydrogels using micelle/emulsion as the pore-forming template. 1H NMR, 13C NMR, FTIR and UV–vis analyses proved that vinyl groups were introduced to SA backbone, and the VSA was reacted with the vinyl monomers by a free-radical polymerization to form a hydrogel network. The nano-pores can be uniformly formed in the hydrogels by introducing micelle template as shown by FESEM observations. The absorption properties of the hydrogels for Pb2+ ions were investigated by evaluating the absorption isotherm and absorption kinetics. Results showed that the hydrogel has higher absorption capacities for Pb2+ ion (432.28 mg/g for 880 mg/L Pb2+ solution and 765.75 mg/g for 2800 mg/L Pb2+ solution), and the formation of nanoporous structure clearly enhanced the absorption rate by 32.56% (for 880 mg/L Pb2+ solution) and 36.79% (for 2800 mg/L Pb2+ solution).