Synthesis of wheat straw-g-poly(acrylic acid) superabsorbent composites and release of urea from it

• Published in: Carbohydrate polymers Vol. 77; no. 2; pp. 181 - 187
• Main Authors: Liang, Rui, Yuan, Hongbo, Xi, Guoxi, Zhou, Qingxiang
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 10.06.2009; Elsevier
• Subjects: absorbance; absorbents; Applied sciences; biopolymers; Cellulose and derivatives; chemical concentration; composite polymers; Equilibrium water absorbency; Exact sciences and technology; graft polymerization; Natural polymers; new products; Physicochemistry of polymers; polymerization; Superabsorbent composite; swelling (materials); synthesis; Urea; water; Wheat straw; Urea; Superabsorbent composite; Equilibrium water absorbency; Wheat straw; Graft copolymer; Property composition relationship; Absorptivity; Grafting; Thermal stability; Straw; Colloidal gel; pH; Water absorption; Release; Acrylic acid copolymer; Absorbent material; Swelling; Lignocellulosics; Experimental study; Vegetal waste; Polyelectrolyte; Ionic strength; Morphology; Preparation; Plant origin; Cereal; Kinetics; Wheat
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2008.12.018

Wheat straw (WS) was used as raw material for synthesizing a novel wheat straw-g-poly(acrylic acid) (WS/PAA) superabsorbent composite by graft polymerization with wheat straw powder and acrylic acid in aqueous solution. The effect of wheat straw on water absorbency was discussed and the highest water absorbency was obtained when the amount of wheat straw in the feed was 20%. The superabsorbent composite was characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The results of FTIR spectra showed OH of WS participated in graft polymerization with acrylic acid. The influences of pH, cations and anions on equilibrium water absorbency of WS/PAA were investigated. The superabsorbent composite was swollen in aqueous solution of urea to load urea, and the results showed urea concentration had no obvious effect on the swelling behaviors of WS/PAA. Furthermore, the release of urea from loaded WS/PAA was analyzed in water and in soil. Urea diffusion coefficient D was calculated.