关键词: 香蕉茎秆纤维, 生物质, 超声预处理, 脱胶率, 半纤维素酶, 果胶酶, 制备, 机械性能

Abstract:

In order to utilize the banana pseudostems, a rich biomass resource in Hainan, the fibers were extracted from banana pseudostem by enzyme treatment. In this work, the better process conditions of frequency and temperature in ultrasonic pretreatment were determined, and two enzymes, hemicellulase and pectinase, were used to remove pectin and hemicelluloses, and to loose the compact structure of fibers, respectively. The better degummed process conditions of the concentration of these two enzymes, reaction temperature and pH value in enzyme process were optimized in terms of degummed rate. The optimum parameters were determined as: the concentration of hemicellulase 0.004 g·ml^-1, reaction temperature 50℃, pH value 5.5, concentration of pectinase 0.003 g·ml^-1, reaction temperature 55℃ and pH value 6.0. Chemical characterization of the banana pseudostem fibers confirmed that the cellulose content was increased from 60% to 65% due to the application of enzyme treatments. The physicochemical properties of enzyme treated banana pseudostem fibers were analyzed by using the fourier transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The tensile properties of enzyme treated banana pseudostem fibers were also investigated. The FTIR and XRD analyses of the enzyme treated banana pseudostem fibers showed an obvious reduction in amount of noncellulosic substances with a crystallinity index of 66.4%. Surface morphological studies using SEM revealed that the enzyme treated banana pseudostem fibers had a rougher surface with a lot of little pectin substance and exhibited brittle fracture. The tensile tests revealed that the tensile strength was about 118.48 MPa with Young's modulus of 15.15 GPa and elongation at break of 0.67%.

Key words: banana pseudostem fibers, biomass, ultrasonic pretreatment, degumming rate, hemicellulose, pectinase, preparation, mechanical properties