Synthesis and properties of sodium alginate/poly(acrylic acid) double-network superabsorbent

A tough double-network (DN) superabsorbent was synthesized by a two-step method using -methylenebisacrylamide as a covalent cross-linker for one monomer [acrylic acid (AA)], Ca (CaCl ) as an ionic cross-linker for the other monomer (sodium alginate [SA]) and ammonium peroxodisulfate as the redox initiator. The optimized experimental conditions for the absorbency in deionized water were determined according to orthogonal experiments. Unlike conventional chemical cross-linked single-network superabsorbents, SA/poly(acrylic acid) (PAA) DN superabsorbents exhibit superb mechanical properties. Compared with the tensile strength of PAA-only superabsorbents, that of SA/PAA DN superabsorbents showed an approximately 371.9% increase with increasing amount of 6 wt.% SA. We also investigated the capacity of SA/PAA DN superabsorbents to remove heavy metal ions. It was found that the addition of SA can truly increase the metal ion removal capacity of the PAA superabsorbents and that the affinity order was Pb >Zn