Preparation and properties of novel eco-friendly superabsorbent composites based on raw wheat bran and clays

Abstract In order to investigate the effect of clay types on the properties of superabsorbent composites, a series of novel eco-friendly clay-based superabsorbent composites were prepared by graft co-polymerization of acrylic acid (AA), wheat bran (WB) and various clays, such as laterite, palygorskite, diatomite and kaolin. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were used to characterize the reaction mechanism and thermal stability of the superabsorbent composites. The properties of the superabsorbent composites were investigated. As a result, the incorporation of clay types had great influence on the properties of superabsorbent composites. The equilibrium water absorbency and the swelling rate in distilled water were always in the order: WB-g-PAA/laterite (647 g/g) > WB-g-PAA (548 g/g) > WB-g-PAA/palygorskite (513 g/g) > WB-g-PAA/diatomite (506 g/g) > WB-g-PAA/kaolin (437 g/g). The percentage of urea loading was 63 wt% (WB-g-PAA/kaolin), 81 wt% (WB-g-PAA/palygorskite), 77 wt% (WB-g-PAA/laterite) and 73 wt% (WB-g-PAA/diatomite) in 9 mg/mL of urea aqueous solution, respectively. Therefore, the WB-g-PAA/clays may have significant potential for agricultural and horticultural application, the types of clay could remarkably affect the properties of the superabsorbent composites type.