Effect of the Delignification Process on the Physicochemical Properties and Thermal Stability of Microcrystalline Cellulose Extracted from Date Palm Fronds

Abstract

In this study, pure cellulose was isolated from Algerian date palm fronds (DPF) using three different delignification processes (acidified NaClO 2 , totally chlorine free (TCF) and their combination). Then, microcrystalline cellulose (MCCs) particles have been successfully produced via direct acid hydrolysis of the different celluloses. All samples were characterized using infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry (TGA) and differential scanning calorimeter (DSC). From the FTIR analysis, most of hemicellulose and lignin were effectively removed throughout the extraction processes. The XRD spectra revealed that all MCCs belong to cellulose I type, and showed a highly crystallinity index than that of pure celluloses. According to DSC and TGA/DTG analyses, the MCC samples presented a higher decomposition temperature. The obtained results showed that the extracted MCC samples exhibited similar properties than those of commercial MCC. Furthermore, the employment of a combined process allowed obtaining MCC with higher crystallinity and better thermal stability. Thus, according to these results, date palm fronds can be considered as a potential low-cost material for MCC production and the combined process is promising to isolate high purity MCC from cellulosic substrate.

Zhurkov’s Stress-Driven Fracture as a Driving Force of the Microcrystalline Cellulose Formation

“…Variations of the destruction activation energy of 10–15% can be caused by the structural reorganization (or stress) of the polymer matrix that was shown for nitrocellulose [ 31 ]. Besides that, the enthalpy of the MCC decomposition process ( –700 J/g) was two-to-three times greater than that of initial cellulose ( J/g), which qualitatively corresponds to the earlier results: the MCC thermal destruction always requires greater energy than initial raw [ 15 , 17 , 20 , 21 , 32 , 33 , 34 ]. Such a ratio confirms our hypothesis.…”

“…The critical step was probably using caustic soda for the acid neutralization after hydrolysis that we did not use. MCC is known to dissolve in alkalis, so even a short treatment with 1 N NaOH [ 15 , 17 , 20 , 21 ] could affect the cellulose structure and cause an increase in the decomposition temperature. Taking the rates of the cellulose and MCC thermal destruction to be approximately equal, the difference in the temperatures of decomposition allows rough accessing the difference in activation energies ( ) of this process: …”

“…The particles’ size does not depend significantly on the cellulose origin and the lignin removal technique [ 19 ]. However, the thermal stability and crystallinity of the MCC depend a bit on the delignification method [ 20 , 21 ]. In the course of acid hydrolysis, the degree of polymerization (DP) of the initial cellulose decreases by a factor of 5–10 [ 15 , 18 , 19 ].…”

“…On average, in raw cellulose, the second peak appears between 320 [ 15 , 17 ] and 350 °C [ 20 , 21 ], depending on the raw used. In MCC, the second peak can be found in a wide range of the temperatures (320–450 °C [ 33 ] either at greater temperatures [ 15 , 20 , 21 , 34 ] or lower temperatures [ 33 ] compared to the raw cellulose. However, the enthalpy of the thermal destruction of MCC was greater than raw cellulose [ 15 ].…”

Development of a microbial coating for cellulosic surface using aloe vera and silane

“…4 (a), peaks at 1458 cm −1 and 1656 cm −1 correspond to the C=C (aromatic ring) and C=O (flavonoids groups), respectively ( Mot, Dumitrescu and Sarbu, 2011 ). Commonly, the peaks at 3336 cm −1 and 2901 cm −1 in uncoated cloth are attribute to -OH stretching groups ( Beroual et al, 2020 , Beroual et al, 2020 ). The C-H bond is stretching vibration of CH 2 group.…”