Facile extraction and characterization of cellulose nanocrystals from agricultural waste sugarcane straw

BACKGROUND Sugarcane straw is an available but largely ignored lignocellulosic biomass to obtain cellulose nanocrystals (CNCs) with highly crystalline, tunable surface chemistries and a wide-ranging adaptability. Herein, we utilized sugarcane straw to obtain pure cellulose via purification processes, followed by subsequent preparation of CNCs via sulfuric acid hydrolysis. The properties of the purified fibers and obtained CNCs were assessed by their composition, morphology, chemical structure, crystallinity and thermal stability. RESULTS After the purification process, alkali-treated fibers (ATFs) contained 886.33 +/- 1.25 g kg(-1) cellulose, and its morphological analysis revealed a smooth and slender fibrous structure. The CNCs obtained by treatment with 64 wt% sulfuric acid at 45 degrees C for 60 min were isolated in a yield of 21.8%, with a diameter and length of 6 to 10 nm and 160 to 200 nm, respectively. Moreover, crystallinity index of these CNCs reached 62.66%, and thermal stability underwent a two-step degradation. Short-term ultrasonication after hydrolysis was employed to enhance isolation of the CNC particles and improve the anionic charge with higher value -38.00 mV. CONCLUSION Overall, isolation and characterization results indicated the potential for CNCs preparation using sugarcane straw, in addition to offering a fundamental understanding of this material and indicating potential applications. (c) 2021 Society of Chemical Industry.

Automated summary

The study focused on utilizing sugarcane straw to obtain pure cellulose and subsequently prepare CNCs with desirable properties. Alkali-treated fibers showed high cellulose content and smooth fibrous structure, while CNCs isolated through sulfuric acid hydrolysis had specific dimensions and improved anionic charge after short-term ultrasonication. Overall, the results suggest the potential for utilizing sugarcane straw in CNCs preparation and possible applications.