Pretreatment and properties of ultrastructural straw used for biological hydrogen production

Abstract

Abstract. Cellulosic biomass can be converted into hydrogen through direct or indirect fermentation pathway. The pretreatment is a key link in hydrogen production process. Especially, mechanical crushing combined with enzymolysis pretreatment process which is an efficiently way. Therefore, it is necessary to study on the pretreatment and properties of ultrastructural straw. The reducing sugar yield which came from the straw after ball milling crushing was used as reference to carry on the single factor and orthogonal experiments to examine the effect of ball milling. Particle size analyzer, scanning electron microscope, X-ray diffraction was utilized to observe the properties of ultrastructural straw. Corncob was measured to have the highest reducing sugar yield. Through analyzing results with DPS analysis software, the optimal parameters of ball milling pretreatment were obtained, as followed: initial size of raw material 0.45mm, ball/powder weight ratio 20:1, milling time 2h. After ball milling, biomass cell wall was effectively opened, specific surface increased, particle size decreased, the microstructure changed and became loose and porous, the cellulose degree of crystallinity were all aggressively lowered, cellulose accessibility was increased, the saccharified rate was improved with the decreasing particle size. All these properties will make the hydrogen producing capacity increased efficiency. These parameters and properties are of great value to reduce the cost of hydrogen production and to promote the development of biological hydrogen production technology by photosynthetic bacteria.