Nanocrystalline Cellulose: Synthesis from Pruning Waste of Zizyphus spina christi and Characterization

Abstract

Nanocrystalline cellulose (NCCs) was synthesized from pruning waste of Zizyphus spina christi using H2SO4 (64 %, wt/wt) under suitable hydrolysis conditions. The crystal growth of the NCCs from nano- into identical micrometric-scaled needles confirmed their ability to self-assembly. The aspect ratio of the NCCs was estimated using optical microscopy for needles, and by scanning electron microscopy (SEM) for powder, while their crystallinity index (CI), crystallite size (CS) and lattice spacing (LS) were estimated by X-ray diffraction (XRD). Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were also performed. The XRD-diffractogram of the NCCs was similar to that known for cellulose I. The CI of the NCCs was much higher (86.75%) than that for cellulose I. The CS of the NCCs was 2.78 nm that is smaller than that for cellulose I. The distance between the strata within the NCCs (LS) was found to be 0.214 nm. The TGA indicated a gradual increase in the mass loss upon heating the NCCs from 25°C up to 500°C in a flowing N2-atmosphere. The DTA showed presence of an endothermic peak (due to H2O-evaporation) and one exothermic peak (due to depolymerization and decomposition of the NCCs. Based on the results, the Zizyphus wood is suitable precursor for the NCCs production.