Fractional Extraction and Structural Characterization of Coconut Shell Hemicellulose

摘要

Three principal components (cellulose, lignin, and hemicellulose) of coconut shell (CS), an abundant tropical biomass, were quantified using the Van Soest method. It was observed that CS had a high content of hemicellulose (30% of the raw CS material). The present study was undertaken to investigate the extractability of hemicellulose from CS obtained by ultrasound-assisted potassium hydroxide solution with the hydrogen peroxide method. The ultrasonic treatment and sequential extractions with alkali and alkaline peroxide under optimal conditions led to a release of more than 93% of the original hemicellulose. The effects of experimental variables, including pH value, reaction temperature and time, hydrogen peroxide content, and magnesium sulfate dosage on hemicellulose content were investigated. The obtained hemicelluloses were characterized by Fourier transform infrared spectroscopy (FT-IR), gel permeation chromatography (GPC), and comprehensive thermal analysis (TGA), which showed that potassium hydroxide significantly affected the yield of relatively pure hemicellulose.