Swelling Properties and Environmental Responsiveness of a Superabsorbent Composite Microsphere Based on Starch-g-Poly(acrylic acid)/Organo-Mordenite

Starch-g-poly(acrylic acid)/organo-mordenite superabsorbent composite microsphere, was prepared by grafting partially neutralized acrylic acid onto starch in the presence of organo-mordenite as an inorganic component. The morphology was characterized with scanning electron microscope (SEM). The swelling properties of the superabsorbent composite microsphere were evaluated in distilled water, various NaCl solutions, solutions with different pH values, and urea solutions. Swelling kinetics of the superabsorbent composite microsphere in above environments were discussed by means of a Schott's second-order model. The results showed that the incorporation of 10 wt% organo-mordenite enhanced the water absorbency by 144% (from 268 to 655 g . g(-1)) and possessed the maximum swelling absorbency (75 g . g(-1)) in the 0.9% NaCl solution and (667 g . g(-1)) in 0.04 mol . l(-1) urea solution. Moreover, swelling of starch-g-poly(acrylic acid)/organo-mordenite (with 10 wt% organo-mordenite) in distilled water and in all other environments followed Schott's second order kinetics. Swelling was extremely environmental-responsive to the concentration of the NaCl solution, the pH values, and urea solutions, respectively. The overall results inferred that the novel superabsorbent composite can be exploited for many potential applications.