Effect of Ultrasonic Pretreatment on the Chemical Composition and Pellet Quality of Camelina Straw

摘要

Densification of biomass into durable pellets enhances its properties for efficient handling, transportation, storage and utilization for biofuel production. However, biomass pellets from straw and stover are often poor in quality. This present studyinvestigates the effect of ultrasonic pretreatment on the chemical composition and quality of camelina straw pellets. Camelina straw ground in 1 mm knife mill screen was subjected to ultrasonic irradiation for 10, 30 and SO min at a frequency of 24 kHz and acoustic power of 120 W; and thereafter pelletized using a single pelleting unit. The microscopic structural changes induced by ultrasonic pretreatment were examined by scanning electron microscopy (SEM). Results indicated a more significant modification in the structure of camelina straw samples subjected to ultrasonic pretreatment at longer residence time as compared to untreated samples. Ultrasonic pretreatment at 50 min sonication time increased cellulose proportion by 2-fold as compared to the control (untreated) and resulted to 12.3% delignification and 16% hemicellulose loss. Ultrasonication of camelina straw had positive impact on the elemental compositions of the camelina straw, increased the gross energy value to 18.39 MJ/kg and led to 50%reduction of the total ash content. Effect of sonication time on pellet density, dimensional stability, durability and tensile strength was not significant at P< 0.05 level. High quality biomass pellets are efficient feedstock for biofuel production viathermo-chemical or biochemical conversion processes.