Crystallization by Acid Hydrolysis-Sulfonation of Cellulose Nanofibers from <i>Eichhornia crassipes</i>

Abstract

This study reports the synthesis of cellulose nanocrystals (CNC) sulfonation from the isolated cellulose nanofibers (CNF) of the Eichhornia crassipes stems. The crystallization of fibers was done by varying the time of sulfonation, 30 min (CNC30) and 60 min (CNC60), in 6M sulfuric acid. Scanning electron microscope images (SEM), and energy dispersive X-ray spectroscopy (EDS) revealed that the crystals have a grain flakey-like structure with the detected presence of oxygen, carbon, and sulfur (due to the sulfonation) atoms. Using Fourier transform infrared spectroscopy (FTIR), unique functional groups of CNCs were detected. Further, the X-ray diffraction (XRD) scans revealed that CNCs have a cellulose-Ib monoclinic unit cell structure with Miller indices (200) and (400). Additionally, results showed that CNC30 has 74.45% and CNC60 has 76.13% crystal index percent and a crystal thickness of 0.048 nm for CNC30 and 0.047 nm for CNC60. Lastly, d-spacing of CNC30 and CNC60 exhibited values of 3.26 Å and 3.20 Å, respectively. These results warrant further studies on future applications of the produced CNC from Eichhornia crassipes fibers.