超声处理对蔗渣在碳酸乙烯酯中液化的影响

Impact of Ultrasonic Pretreatment on the Liquefaction of Bagasse in Ethylene Carbonate

研究了超声处理对蔗渣形态结构以及蔗渣在碳酸乙烯酯中液化行为的影响。蔗渣经超声处理后,表面变得较粗糙,细胞壁在一定程度上破碎,出现很多微孔,从而有利于液化反应的进行。蔗渣超声处理前后的红外光谱表明,纤维的组成和结构并无明显变化。实验表明,当超声频率为28 kHz时,蔗渣液化反应的残渣率最低。延长超声处理时间或者增大超声功率都有利于降低液化反应的残渣率。超声处理缩短了液化达到最低残渣率的时间。合适的超声处理可以使液化产物的相对分子质量分布变窄,但对液化产物相对分子质量影响较小。

The influences of ultrasonic pretreatment on the morphology and liquefaction behavior of bagasse were studied. SEM images showed that the fiber surface of bagasse became less compact and the cell wall was broken severely after sonication. The FT-IR spectra of bagasse, however, showed that no significant change of chemical structure occurred after sonication. These increase the accessibility of the bagasse fiber, accelerate the liquefaction, decrease the coupling of the free radicals derived from the liquefaction intermediates, which are in favor of liquefaction. The impacts of the sonication time, the frequency and the power of ultrasound on the morphology and liquefaction behavior of bagasse were investigated. The result showed that suitable frequency for the treatment is 28 kHz. Both prolonging the time of son- ication and increasing the power of ultrasound reduce the residue rate of the liquefaction. The liquefaction process is also accelerated after sonication. The relative molecular weight distribution of the liquefaction product, however, has little change after the ultrasonic pretreatment, indicating that the liquefaction mechanism is not changed by sonication.