Optimization of the Obtaining of Cellulose Nanocrystals from Agave tequilana Weber Var. Azul Bagasse by Acid Hydrolysis

Abstract

A multilevel factorial design of 23 with 12 experiments was developed for the preparation of cellulose nanocrystals (CNC) from Agave tequilana Weber var. Azul bagasse, an agro-industrial waste from tequila production. The studied parameters were acid type (H2SO4 and HCl), acid concentration (60 and 65 wt% for H2SO4, 2 and 8N for HCl) temperature (40 and 60 °C for H2SO4, 50 and 90 °C for HCl), and hydrolysis time (40, 55 and 70 min for H2SO4; and 30, 115 and 200 min for HCl). The obtained CNC were physical and chemically characterized using dynamic light scattering (DLS), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XDR) techniques. The maximum CNC yield was 90 and 96% for HCL and H2SO4, respectively, and the crystallinity values ranged from 88–91%. The size and morphology of A. tequilana CNC strongly depends on the acid type and hydrolysis time. The shortest CNC obtained with H2SO4 (65 wt%, 40 °C, and 70 min) had a length of 137 ± 68 nm, width 33 ± 7 nm, and height 9.1 nm, whereas the shortest CNC obtained with HCl (2 N, 50 °C and 30 min) had a length of 216 ± 73 nm, width 69 ± 17 nm, and height 8.9 nm. In general, the obtained CNC had an ellipsoidal shape, whereas CNC prepared from H2SO4 were shorter and thinner than those obtained with HCl. The total sulfate group content of CNC obtained with H2SO4 increased with time, temperature, and acid concentration, exhibiting an exponential behavior of .

Cellulose Nanocrystals Derived from Microcrystalline Cellulose for Selective Removal of Janus Green Azo Dye

“…8 The crystalline portions of the cellulose can be separated from the amorphous region by acidic hydrolysis. 9 The kinetic force and steric barrier in the amorphous parts of the cellulose chain make it most accessible to the acid for hydrolytic activity. At the same time, the crystalline sections are less affected by hydrolysis.…”

“…Cellulose contains two regions: an ordered crystalline region and another amorphous region . The crystalline portions of the cellulose can be separated from the amorphous region by acidic hydrolysis . The kinetic force and steric barrier in the amorphous parts of the cellulose chain make it most accessible to the acid for hydrolytic activity.…”

Part A: Biodegradable Bio-Composite Film Reinforced with Cellulose Nanocrystals from Chaetomorpha linum into Thermoplastic Starch Matrices

“…The in-depth analysis of the FTIR spectrum combined with the information collected in the literature makes it possible to distinguish the signals in a very specific manner. However, the exceptional FTIR region for the detection of cellulose crystallinity ranged from 850 to 1500 cm −1 [ 28 , 29 ]. The order index is defined by O’Connor et al [ 29 ], as the absorbance ratio of the bands detected at 1430 and 900 cm −1 , known as crystalline and amorphous cellulose bands, occurring as a result of CH 2 vibration (the symmetric and rolling bending, respectively), and it is also defined as LOI: A1430/A908 [ 28 ].…”

Dynamic Light Scattering Plus Scanning Electron Microscopy: Usefulness and Limitations of a Simplified Estimation of Nanocellulose Dimensions

“…Indeed, DLS is a non-destructive, extremely popular technique to measure particle size [ 9 , 10 , 11 ]. It has been satisfactorily used to measure the size of CNCs in multiple reports [ 11 , 12 , 13 , 14 ]. However, we must display a critical approach when addressing DLS for CNC dimensions.…”