The Effect of Particle Size of Almond Shell Powders, Temperature and Time on the Extraction of Cellulose

The extraction of cellulose from almond shell powders was carried out using three different particle sizes (125 µm, 250 µm, and 500 µm) of the powders. The powder samples were subjected to Soxhlet extraction using an ethanol and methanol volume ratio of 2:1 for 6 hours to remove impurities such as waxes, resins, and dust. The dewaxed product was further hydrolyzed with 10% sodium hydroxide to remove the hemicellulose. The delignification of the hydrolyzed powder extracts was achieved with 10% acidified sodium chlorite. The percentage yield of the pure cellulose extracts for the 125, 250, and 500 µm particle sizes were 25%, 52.2%, and 42.6%, respectively. Fourier transformed infrared (FTIR) spectroscopy confirmed the removal of hemicellulose and lignin after the chemical treatment. Field emission scanning electron microscopy (FESEM) images revealed a smooth textural surface of the micro-cellulose. X-ray diffraction (XRD) demonstrated high crystallinity of the cellulose, while thermogravimetric analysis (TGA) indicated high thermal stability of the cellulose extract. This confirmed that cellulose was successfully extracted from almond shell powders of three different particle sizes which could serve as raw material for nanocellulose extraction.