Cellulose fibers extracted from sesame hull using subcritical water as a pretreatment

Abstract

Sesame processing facilities typically discard sesame seed hulls (SH) as waste or animal feed. However, these hulls are rich in cellulose and make them potentially valuable to the food industry. This study for the first time studied the effect of subcritical water (SW) and alkali (AT) pretreatment on extraction of purified cellulose from SH. The results indicated that the yield of SWCs (cellulose obtained by subcritical water pretreatment, 9.2–11.6%) was close to that of ATC (cellulose obtained by alkali pretreatment, 10.1%). Crystallinity of SWCs (68.7–75.8%) was significantly higher than ATC (60.9%). Subcritical water pretreatments interfered more significantly than alkali with the removal of non-cellulosic components according to Fourier transform infrared spectrometry and scanning electron microscope photographs. In addition, the diameter of the SWC was smaller than ATC, and the obtained SWC was comparable to ATC in terms of thermal stability. This study shows that subcritical water, as an environmentally friendly solvent, can be used to extract good quality cellulose from SH. In addition, subcritical water is more effective than alkali, suggesting it could be used more widely in the food industry for producing cellulose from other sources.

Keywords

• Sesame hull
• Subcritical water
• Pretreatment
• Cellulose