Optimizing Cellulose Extraction from Kenaf (Hibiscus Cannabinus L.) Fiber by Selective Retting and Hydrothermal Pretreatment

This study investigated the effects of hydrothermal pretreatment on the properties of water and enzyme retted kenaf (Hibiscus cannabinus L.) fibers after treatment in a high-pressure reactor at 160, 180, and 200 degrees C for 40 min. The retted fibers were characterized by chemical analysis, field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results showed that the cellulose content increased after the fibers were retted using water or enzymatic retting, the FE-SEM analysis found changes in the surface morphology of the treated fibers, and the results of the chemical analysis and FTIR showed that the amount of hemicellulose content decreased as the treatment temperature increased. In addition, the XRD results showed that the crystallinity of the treated-fibers and the extraction processing did not affect the crystalline structure of the cellulose, while the results of the TGA indicated that the thermal stability of the treated fibers was higher than that for untreated fibers. Finally, it was determined that the cellulose yield was the highest when the kenaf was pre-treated at 180 degrees C.