Jianqiang Chen

Dissolution of wheat straw with aqueous NaOH/Urea solution

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.

Bio-based Plastics with Highly Efficient Esterification of Lignocellulosic Biomass in 1-methylimidazole under Mild Conditions

Lignocellulosic biomass is regarded as one of the most abundant and sustainable resources for the development of bio-based plastics. The esterification of wood with phthalic anhydride (PA) yields low content due to lack of an efficient modification medium. In the present study, 1-methylimidazole was used as a catalytic medium for the highly efficient esterification of waste lignocellulosic biomass (poplar wood, mulberry wood, and wheat straw) with PA. After modification, the wood particles were plasticized and molded via injection molding. Analyses of the weight percent gain showed that under the same conditions, poplar wood, which has a soft and loose structure, presented the highest extent of esterification, whereas mulberry wood, which has a tight texture, had the lowest extent of esterification. Mulberry wood-based plastics exhibited the best performance in terms of flexural and tensile strength. Notably, short reaction time was favorable to produce bio-based plastics that were light in color. FT-IR spectroscopy and solid-state 13 C NMR spectroscopy confirmed the chemical structures of the esterified products. Dynamic mechanical analysis was used to identify the storage modulus and the damping factor of the esterified products. Analyses of the morphologies of the materials demonstrated different composite structures for the bio-based plastics, which played an important role in their mechanical performance.