Highly-efficient Isolation of Microcrystalline Cellulose and Nanocellulose From Sun Flower Seeds Waste via Environmentally Benign “soft” Method

Abstract

The main focus of this study was to introduce a natural microcrystalline cellulosic raw material source from the residue of sunflower seeds, after oil extraction. For this purpose, the conventional method of organosolvent oxidation was changed to a "soft" method where microcrystalline cellulose (MCC) was extracted from sunflower seed husk (SFH) and the characterization of MCC and cellulose nanocrystals (CNCs) were carefully carried out. In this method, the concentration of acetic acid and hydrogen peroxide required for the preparation of peroxyacetic acid (PAA) was reduced by two times. The physico-chemical characterization, particle size, optical properties, chemical and crystal structure, surface morphology, and thermal stability of MCC and CNC were studied. The FTIR analysis, revealed the structural similarity of all derivatives of cellulose. Surface morphology was monitored with SEM, and the surface of MCC fibers was rough, and the morphology of cellulose nanocrystal (CNC) was fine, smooth and rod-like (overlapping each other) appearance, CNC film surface was found to be brown was filled with nano fibrils. The XRD analysis and determination of average particle size revealed that the MCC had a CI of 72.9%, a coherent scattering length (CSL) of 2.9 nm, and an average particle size of 1971 nm along the fibers, and a width of 266 nm. The acid hydrolysis resulted in the reduction of length of CNCs by 4 times and the width was reduced about 5 times. At the same time there observed an increase in the crystallinity index (CI) value. It was found that cellulose materials were destroyed at temperatures between 200ₒС and 358ₒС. Overall, it was concluded that sunflower seed husk was considered as a potential source for CNCs and the method employed for the extraction of cellulose from agricultural biomass waste was cost effective and environmentally benign.