Preparation, Characterization and Swelling Behaviours of a Novel Multifunctional Superabsorbent Composite Based on Ca-Montmorillonite and Sodium Humate

Abstract

AbstractIn this work, a novel water-managing superabsorbent composite was prepared by graft copolymerization reaction using acrylic acid (AA) and acrylamide (AM) as the monomers, calcium montmorillonite (Ca-MMT) as an inorganic component and sodium humate (SH) as fertilizer, and well characterized by means of Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The effects of the reaction temperature, neutralization degree of AA, amount of crosslinker, initiator, Ca-MMT and SH on water absorbencies were systematically investigated. The water absorbencies of the superabsorbent composite synthesized under optimal conditions with a Ca-MMT content of 20 wt% and an SH content of 30 wt% are 615 g g-1 and 45 g g-1 in distilled water and in 0.9 wt% NaCl solution, respectively. The swelling behaviours of the superabsorbent composite in various cationic salt solutions (NaCl, CaCl2 and FeCl3) were also investigated and it was found that at the same saline concentration (> 0.1 mmol L-1), the effect of three cationic salt solutions on the swelling capability has the following order: NaCl < CaCl2 < FeCl3. Here, it is worthy to point out that the water absorbency and swelling behaviours of the developed composite were improved by introducing simultaneously Ca-MMT and SH into PAA-AM network in comparison with that of incorporated single with Ca-MMT or SH.