Dissolution of wheat straw with aqueous NaOH/Urea solution

• DOI: 10.1007/s12221-015-3680-z
• Publication Date: 2015-12-01T03:44:41Z
• Authors: Xiaobao Li; Judi Ye; Jianqiang Chen; Ji Yu; Minmin Ding; Jianguo Hong
• Keywords: 01 natural sciences; 6. Clean water; 0104 chemical sciences

Aqueous NaOH/urea solution employed to dissolve lignocellulosic biomass is promising. In this work, wheat straw was found to be partially dissolved in the aqueous NaOH/urea solution, and the dissolved substances can be further flocculated by adding diluted sulfuric acid as a coagulating agent. The dependence of solubility of wheat straw on volume of NaOH/urea solution, concentration of NaOH, and dissolving duration and temperature was systematically investigated. Selected samples were characterized by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), and solid-state 13C nuclear magnetic resonance (13C-NMR). At optimal process condition, 61.22 wt% wheat straw dissolved in 50 ml NaOH/urea solution (NaOH:urea:H2O=10:9:81 wt%) within 2 h at −10 °C, and a cellulose-rich floccule containing 84.95 wt% holocellulose and 7.28 wt% lignin formed was obtained.