Extraction And Characterization Of Hemicelluloses From Coconut Shell

To solve the problem resulted from energy shortage and environmental pollution, conversion of biomass wastes into new materials, chemicals, resources and medicine to replace dwindling petrochemical-based feedstock is increasingly attracting more and more worldwide attentions. In order to utilize the coconut shell to convert to high-value materials, the fractional isolation of hemicelluloses from coconut shell, by dilute sulfuric acid hydrolysis and alkaline solution of hydrogen peroxide combined with ultrasound-assisted, was investigated. Meanwhile, the structural characterization of the coconut shell hemicelluloses was carried out via FT-IR spectra analysis, thermal analysis and Gel-Permeation Chromatography (GPC). And the results are described as follows:The extraction of hemicelluloses from coconut shell by dilute sulfuric acid hydrolysis was carried on by orthogonal experiment to study the influence of the sulfur acid concentration, the ratio of solid and liquid, reaction temperature and reaction time. As a result, the level of various experimental factors impact on the extraction of hemicelluloses from coconut shell by a large array as follows:reaction temperature> the ratio of solid and liquid> reaction time> the concentration of sulfuric acid. And the optimal conditions of the extraction of hemicelluloses:reaction temperature95℃, the ratio of solid and liquid1:18, reaction time150min, the sulfuric acid concentration4%.In the study of coconut shell hemicelluloses extraction using alkaline solution of hydrogen peroxide, single-factor experiment design and orthogonal experiment was undertaken to investigate the influence of the concentration of hydrogen peroxide, magnesium sulfate concentration, reaction temperature, reaction time, and pH value. The results showed that the optimal conditions of the extraction of hemicelluloses by alkaline solution of hydrogen peroxide was found to be at8%(w/v) hydrogen peroxide, for4h and60℃, after20mins ultrasound pre-treatment.And the hemicelluloses with a high yield of16.44%can be obtained comparing to raw materials.Meanwhile, the results also illustrated that pH value, concentration of H2O2, magnesium sulfate concentration were the most important factors impact on the extraction of coconut shell hemicelluloses. Between these factors, there were some important interaction and interrelation. And these interrelation could impact on the concentration of HO-and O2, which would cause some linkages between hemicellulose, cellulose and lignin to be broken, and finally cause hemicellulose decomposition.