Synthesis and characterization of chitosan-g-poly(acrylic acid)/attapulgite superabsorbent composites

A novel chitosan-g-poly(acrylic acid)/attapulgite superabsorbent composite with water absorbency of 159.6 g g−1 in distilled water and 42.3 g g−1 in 0.9 wt% NaCl solution was prepared by graft polymerization with chitosan, acrylic acid and attapulgite in aqueous solution, using N,N′-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. Factors influencing water absorbency of the superabsorbent composite were investigated, such as average molecular weight of chitosan, weight ratio of acrylic acid to chitosan, dewatering method, the amount of crosslinker and attapulgite. The result from FTIR spectra showed that –OH of attapulgite, –OH, –NHCO and –NH2 of chitosan participated in graft polymerization with acrylic acid. The introduced attapulgite enhanced thermal stability of the chitosan-g-poly(acrylic acid) superabsorbent and formed a loose and more porous surface. Introducing a small amount of attapulgite also enhanced water absorbency of the chitosan-g-poly(acrylic acid) superabsorbent.