Preparation and anti-evaporation properties of organic–inorganic superabsorbent based on Tragacanth gum and clay

In this study, the application of superabsorbent resin (SAP) in inhibiting the soil moisture evaporation (or slowing down the water outflow) was studied. The clay-SAP composites were fabricated by grafting of poly (acrylic acid-N-hydroxymethyl acrylamide/clay) (GT-g-P [AA-co-NHA]/clay) on Tragacanth gum (GT), using solution polymerization. The structure, morphology and stability of the clay-SAP composites were investigated by Fourier transform infrared, scanning electron microscope and TGA. The maximum swelling ratio of Attapulgite (3%)-, Kaolin (3%)- and Montmorillonite (3%)-SAP composite in deionized water reached 1180, 819 and 525 g/g respectively, and the maximum swelling ratio in tap water reached up to 206, 192 and 170 g/g respectively. Meanwhile, the maximum swelling ratio in 0.9% NaCl solution was 95, 82 and 62 g/g respectively. The water retention of clay-SAP composites was also analyzed as a function of temperature. In addition, by simulating the desertification area, the effect of the APT (3%)-SAP composite on the anti-evaporation performance was studied. The obtained results revealed that the water retention of APT (3%)-SAP composite was 36% at 45°C for 12 h. Under natural conditions, the evaporation rate of the anti-evaporation material was inversely proportional to the amount of APT (3%)-SAP composite added.