Morphological, Spectroscopic and Thermal Analysis of Cellulose Nanocrystals Extracted from Waste Jute Fiber by Acid Hydrolysis

Abstract

Natural cellulose, a sustainable bioresource, is highly abundant in nature. Cellulosic materials, particularly those that explore and employ such materials for industrial use, have recently attracted significant global attention in the field of material science because of the unique properties of cellulose. The hydroxyl groups enable the formation of intra- and inter-molecular hydrogen bonding and the arrangement of cellulose chains in a highly ordered crystalline zone, with the remaining disordered structure referred to as an amorphous region. The crystalline areas of cellulose are well-known as cellulose nanocrystals (CNCs). In the present study, we extracted CNCs from pure cellulose isolated from waste jute fibers by sulfuric acid hydrolysis, followed by characterization. Pure cellulose was isolated from jute fibers by treating with sodium hydroxide (20% w/w) and anthraquinone (0.5%) solution at 170 °C for 2 h, followed by bleaching with chlorine dioxide and hydrogen peroxide solution. CNCs were isolated from pure cellulose by treating with different concentrations (58% to 62%) of sulfuric acid at different time intervals (20 min to 45 min). The FTIR study of the CNCs reveals no peak at 1738 cm−1, which confirms the absence of hemicellulose in the samples. The CNCs obtained after 45 min of acid hydrolysis are rod-shaped, having an average length of 800 ± 100 nm and width of 55 ± 10 nm, with a high crystallinity index (90%). Zeta potential significantly increased due to the attachment of SO42− ions on the surface of CNC from −1.0 mV to about −30 mV, with the increment of the reaction time from 20 min to 45 min, which proved the higher stability of CNC suspension. Crystallinity increased from 80% to 90% when the reaction time was increased from 20 to 45 min, respectively, while a crystallite size from 2.705 to 4.56 nm was obtained with an increment of the acid concentration. Acid hydrolysis enhanced crystallinity but attenuated the temperature corresponding to major decomposition (Tmax) at 260 °C and the beginning of degradation (Ti) at 200 °C due to the attachment of SO42− ions on the surface, which decreased the thermal stability of CNC. The second degradation at 360 °C indicated the stable crystal structure of CNC. The endothermic peak at 255 °C in the DTA study provided evidence of sulfated nanocrystal decomposition and the recrystallization of cellulose I to cellulose II, the most stable structure among the other four celluloses. The proposed easy-to-reproduce method can successfully and efficiently produce CNCs from waste jute fibers in a straightforward way.

Modification of Bulk Density, Flow Property and Crystallinity of Microcrystalline Cellulose Prepared from Waste Cotton

“…The cellulose XRD diffraction patterns were obtained at 2θ = 22.5° which correspond to the lattice planes 200 in the cellulose lattice ( Figure 5 ). The presence of crystalline cellulose [ 43 , 44 ] was confirmed by the occurrence of a large crystalline peak at 22.5° in all the samples including standard, unmodified and modified MCC. The percent crystallinity indexes (CI) of the standard MCC (Avicel PH101), MCC-UM, MCC-M1, MCC-M2, MCC-M3, MCC-M4 and MCC-M5 were 87.63, 86.82, 74.23, 73.83, 60.70, 62.37 and 80.18, respectively.…”

Isolation and Characterization of Spherical Cellulose Nanocrystals Extracted from the Higher Cellulose Yield of the Jenfokie Plant: Morphological, Structural, and Thermal Properties

“…Acid hydrolysis caused the nanocrystals’ surface to become less thermally stable, which led to the maximum breakdown occurring at low temperatures as a result of sulfate ion attachment [ 74 ]. The more thermally stable and exothermic third peak occurred at temperatures of 334 and 462 °C for the J–MC and at a temperature of 444 °C for the J–CNC samples, respectively, indicating the depolymerization of glycosyl units and the formation of carbonaceous residues [ 75 ]. There are several reasons why J–CNC depolymerizes, including (i) its nano-size and higher number of free ends, which break down at a reduced temperature; (ii) the presence of sulfuric acid, which makes cellulose easier to depolymerize by eliminating some hydroxyl groups; (iii) the abundance of H+ ions in the weakly acidic atmosphere, which increases the amount of char residue through the elimination of oxygen in the form of water, preventing weight losses; and (iv) the highly crystalline nature of J–CNC increases the number of carbon residues [ 76 , 77 , 78 ].…”

“…The maximum crystallinity index of J–CNC found in this investigation (98.8%) is in line with other higher cellulose nanocrystals of Kombu that have been researched, including cotton filter (93.4%), rice straw (91.2%), South African cotton (SANC) (97.8%, Chinese cotton (92.4%), cotton cloth waste (95%), and sugarcane peel (SPCNC) (92.2%) [ 70 , 85 , 86 , 87 , 88 ]. Additionally, the creation of highly crystalline, stable nanocellulose is favored by a higher achieved crystallinity index [ 75 ]. Because of its high CrI, spherical nanocellulose may enhance the mechanical, thermal, and other properties of nanocellulose composites [ 44 ].…”

Preparation of aldehyde-functionalized cellulose nanocrystals via aerobic oxidation of cellulose in a recyclable triisopropoxy vanadium oxidation system

“…11 Inorganic acids have low efficiency and strong corrosion to equipment, which limit their use in large-scale preparation. 12 Compared to acid hydrolysis, oxidative preparation of nanocellulose results in the presence of functional groups including carboxyl and aldehyde groups on the surface, 13 which facilitates the surface modification of nanocellulose, making it highly suitable for the development of functional materials. 14 At present, the most commonly used oxidation method involves the use of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) as an oxidant to oxidize cellulose C 6 hydroxyl groups to carboxyl groups.…”