Preparation of Nanostructured Cellulose via Cr(III)- and Mn(II)-Transition Metal Salt Catalyzed Acid Hydrolysis Approach

Abstract

Nanostructured cellulose was successfully prepared from native cellulose using a homogeneous catalytic H2SO4 hydrolysis pathway in the presence of Cr(III)-and Mn(II)-transition metal salts as the co-catalyst. The effect of transition metal salts with different valence states (Cr 3+ and Mn 2+) on the physicochemical properties (chemical characteristics, crystallinity index, nano-structure, thermal stability, and morphology) of prepared nanocellulose was investigated. Interestingly, TEM micrographs showed that the Cr(III)-treated and Mn(II)-treated nanocellulose exhibited a weblike nanostructured-surface with average diameters of 44.7 ± 13.2 nm and 58.4 ± 15.3 nm, respectively. XRD study revealed that the crystallinity of nanocellulose was increased because the catalytic degradation of the less crystalline regions of cellulose occurred at a faster rate than its crystalline phases. Cr(III)-treated nanocellulose was capable of rendering a higher crystallinity index (75.6 ± 0.1%) compared with Mn(II)-treated nanocellulose (72.3 ± 0.4%). Furthermore, a dynamic light scattering (DLS) study revealed that Cr(III)-treated nanocellulose showed a smaller distribution range (92% at 14 to 135 nm) compared with Mn(II)-treated nanocellulose (92% at 607 nm). A higher valence state for the Cr(III)-cation, with a trivalent state (+3), rendered a more effective hydrolysis reaction compared with the Mn(II)-cation, with a divalent state (+2), for preparing the nanocellulose.

Easy Fabrication of Highly Thermal-Stable Cellulose Nanocrystals Using Cr(NO3)3 Catalytic Hydrolysis System: A Feasibility Study from Macro- to Nano-Dimensions

“…As presented in Figure 3, the FTIR spectra of all the samples exhibited two major absorbance regions, which included the high (3500–2800 cm −1 ) and low wavenumbers (1700–500 cm −1 ) regions, consistent with previous studies [38,39]. A broad and dominant absorbance peak located in the region of 3600 to 3200 cm −1 was observed in all spectra, which corresponded to the characteristic of hydrogen bonding O–H stretching vibrations [40].…”

Recent Strategies in Preparation of Cellulose Nanocrystals and Cellulose Nanofibrils Derived from Raw Cellulose Materials

“…The crystallinity index was 86.5% ± 0.3% and the maximum thermal decomposition temperature was 344 ∘ C. The hydrolysis system of Cr(NO 3 ) 3 -H 2 SO 4 was also investigated by Chen and coworkers [127]. In this work, the maximum yield and highest crystallinity of CNCs were obtained under hydrolysis conditions of 0.22 M Cr(NO 3 ) 3 , 0.80 M H 2 SO 4 , and 82.2 ∘ C within 1 h. Other transition metals were examined as well for catalyzing the hydrolysis of raw cellulose materials to prepare CNCs, such as Fe(III), Al(III), Ni(II), Co(II), and Mn(II) [68,128,129], and they will not be elaborated in detail.…”

MoS2/cellulose-doped ZnO nanorods for catalytic, antibacterial and molecular docking studies

“…The band at ~829 cm -1 represents ZnO lattice vibrational frequency, meanwhile the peaks flexing at 1329 cm -1 and 669 cm -1 were attributed to ZnO formation [13,38]. CNC absorption peak observed at 1110 cm -1 derived from C-O-C pyranose ring vibration [39]. More importantly upon MoS 2 doping, two additional peaks 1638 cm -1 and 2069 cm -1 were observed, which might be linked with the Mo-S vibration.…”