Synthesis and characterization of hydroxyl poly(aspartic acid)/organic bentonite superabsorbent composite

Abstract

A novel hydroxyl poly(aspartic acid)/organic bentonite (HPAsp/OB) superabsorbent composite has been synthesized by the non-water suspension method using polysuccinimide and OB as raw materials,ethanolamine as modifiers and hexamethylenediamine as cross-linking agent. Organic bentonite used in this work is cetyl trimethyl ammonium bromide intercalated bentonite with the interlayer distance of 2.12 nm. The effects of the OB and ethanolamine contents on swelling ratios of the superabsorbent composites have been investigated. The largest swelling ratios in distilled water and in 0.9 wt% NaCl were 491 and 82 g/g, respectively, both at OB and ethanolamine contents of 3 wt% and 15 mol%, correspondingly. The salt resistance of the superabsorbent composites was investigated in KCl (aq.), CaCl2 (aq.) and FeCl3 (aq.). The temperature- and pH-sensitivities of the superabsorbent composites has also been studied. The structures and morphologies of the superabsorbent composites have been characterized by Fourier transform infrared spectroscopy, X-ray diffraction, high resolution-TEM and optical microscopy techniques. The results indicated that introduction of OB and ethanolamine increased the swelling ratio of the superabsorbent composites. Compared with poly(aspartic acid), hydroxyl poly(aspartic acid) and poly(aspartic acid)/organic bentonite, the swelling properties of HPAsp/OB superabsorbent composites are obviously improved under the same experimental conditions.