Investigation of nanostructure of konjac-based water absorbents with atomic force microscopy

Abstract

Atomic force microscopy technology is gradually spreading to almost all aspects, including food science and technology, since it was first invented in 1986. In this study, this powerful instrument was applied to image nanostructures of three water absorbents—original konjac powder, konjac powder grafted with acrylic acid using ⁶⁰Co γ-irradiation and regenerated grafted powder. Water absorption capacities and the rates of the three absorbents were also determined in this work. Original konjac powder could only absorb 60 times (w/w) of water, while 270 times for the grafted absorbent and 360 times for the regenerated absorbent. The initial water absorption rates in both tap and distilled water were high, but the rate decreased steeply as time elapsed. After 20min, the absorbent was close to saturated status. These physical properties were in accordance with the nanostructures of these three water absorbents.