Rapid synthesis of a superabsorbent from a saponified starch and acrylonitrile/AMPS graft copolymers

In this work, superabsorbents comprising the graft polymer of acrylonitrile and AMPS onto starch were prepared using a manganic pyrophosphate redox initiation system. The addition of AMPS results in a gradual saponification time decrease for the graft polymer, then the total synthesis time decrease of superabsorbents. The effect of KOH volume, KOH concentration, saponification temperature on the water absorbency of superabsorbent was investigated using response surface methodology (RSM). The maximum response at the optimal saponification conditions can be obtained. The water absorbency was 1345 g/g dry superabsorbent, using the following saponification conditions: KOH volume 203.7 ml, KOH concentration 0.51 mol/l, saponification temperature 92.6 °C. The shortest saponification time is 17 min, then the total synthesis time of superabsorbents is 2.5 h.