A new method for determination of lignocellulose crystallinity from XRD data using NMR calibration

Abstract

A new method was proposed which allowed more accurate crystallinity results for lignocellulose comparing to conventional calculation models. The method is based on the estimation of the changing rate of the XRD intensity I = f(2θ) over the entire range of scattering angles. Pure crystalline and amorphous cellulose were used as calibration samples, since cellulose crystallinity can be easily determined by 13C CP/MAS NMR. The method was successfully applied to three types of plant biomass model mixtures, such as a mixture of birch xylem with micro crystalline cellulose, a mixture of birch xylem with alkaline sulfate lignin, and a mixture of alkaline sulfate lignin with microcrystalline cellulose. The obtained crystallinity depended linearly on the content of microcrystalline cellulose in the sample. The proposed equation can be used to calculate the crystallinity degree of lignocelluloses, as well as any lignocellulose materials.

Keywords

• Cellulose
• Crystallinity degree
• Lignocellulose
• X-ray diffractometry
• 13C CP/MAS NMR spectroscopy