Extraction and characterization of cellulose and cellulose nanocrystals from the stalks of Marrubium vulgare plant

Abstract

In this study, we report on how cellulose and nanocellulose can be extracted and prepared, respectively, from the Marrubium vulgare plant by employing environmentally friendly multistep chemical procedures. These multistep procedures include soxhlet extraction, alkaline treatment, and entirely chlorine-free bleaching methods. Specifically, soxhlet extraction is employed for the removal of pectin, cutin, waxes and other extractives, while alkaline treatment is employed to eliminate hemicellulose and lignin and, finally, bleaching methods are utilized for the delignification of the cellulosic biomaterial. Fourier transform infrared (FTIR) provided evidence on successful elimination of hemicellulose, lignin, and other non-cellulosic material. X-ray Diffraction (XRD) analysis revealed crystallinity of the extracted cellulosic material; hence the Segal method was utilized to determine the level of crystallinity of 63.58±5 %. Additionally, the Scherrer equation was employed to determine the thickness of the crystals of about 32.5 ± 10 Å. Thermogravimetric analysis (TGA) revealed the cellulosic materials’ thermal degradation behavior. Lastly, the acid hydrolysis of cellulosic material with sulfuric acid led to the formation of nanocellulose as characterized via transmission electron microscopy (TEM). It was observed that the extracted nanocellulose exhibited an average length of 409.3 ± 0.42 nm and width of 55.7 ± 0.36 nm with an average aspect ratio of 7.34 ± 0.05.