Synthesis and characterization of chitosan-g-poly(acrylic acid)/sodium humate superabsorbent

A novel chitosan-g-poly(acrylic acid)/sodium humate (CTS-g-PAA/SH) multifunctional superabsorbent was prepared by graft polymerization among chitosan, acrylic acid and sodium humate in aqueous solution, using N,N′-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. And the samples were further characterized by means of FTIR, SEM and TGA. The effect of polymerization variables, including reaction temperature, content of initiator, crosslinker and sodium humate, the weight ratio of acrylic acid to chitosan, on water absorbency were studied. The swelling rate in distilled water and the swelling behavior in various pH value solutions were also investigated. The result from FTIR spectra showed that chitosan and sodium humate participated in graft polymerization reaction with acrylic acid. The introduced sodium humate could enhance water absorbency and the content of 10 wt% sodium humate gave the best absorption (183 g g−1 in distilled water and 41 g g−1 in 0.9 wt% NaCl solution).