Synthesis and characterization of cellulose nanocrystals derived from walnut shell agricultural residues

• Published in: International journal of biological macromolecules Vol. 120; no. Pt A; pp. 1216 - 1224
• Main Authors: Hemmati, Farshad, Jafari, Seid Mahdi, Kashaninejad, Mahdi, Barani Motlagh, Mojtaba
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.12.2018
• Subjects: Cellulose - chemical synthesis; Cellulose - chemistry; Cellulose nano-crystals; Characteristics; Chemistry, Agricultural; Hydrolysis; Juglans - chemistry; Nanoparticles - chemistry; Spectroscopy, Fourier Transform Infrared; Walnut shell; X-Ray Diffraction; Cellulose nano-crystals; Walnut shell; Characteristics
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2018.09.012

Cellulose nanocrystals (CNCs) have novel and diversified applications in different fields including packaging and nanodelivery systems. This study was dedicated to fabricate CNCs from walnut shell as an abundant source of agricultural byproducts using alkali/acidic hydrolysis method. Moreover, homogenizer and ultrasound devices were applied to produce the CNCs with minimum hazardous solvents in the preparation steps. The physicochemical characteristics of CNCs, such as color, size, yield, and swelling capacity plus their characterization using X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier-transform infrared spectroscopy (FTIR) were studied. The mean equivalent spherical diameter of the fabricated CNCs was about 130 nm and the production efficiency was 91.5%. Besides, the swelling capacity of CNCs was 1.5-fold of cellulose with a swelling of 400%. The crystallinity degree of the cellulose obtained from walnut shell was 49%, which was improved following acidic and alkali hydrolysis (60%). TGA analysis revealed that the thermal stability of the CNCs was lower than cellulose; moreover, the FTIR results demonstrated that there is not a considerable difference between normal cellulose and CNCs. Overall, it was concluded that walnut shell-derived CNCs have the potential to be employed as promising nanocarriers in different sectors, especially in the food and drug delivery sectors. [Display omitted] •Walnut shells were used as a cost-effective source for production of CNCs.•CNCs produced via acid hydrolysis combined with sonication and homogenization.•Mean equivalent spherical diameter of CNCs was 130 nm.•The crystallinity index of CNCs was higher than crude cellulose from walnut shell.•CNCs showed a lower degree of thermal stability than normal cellulose.