Acid pre-treatment technologies and SEM analysis of treated grass biomass in biofuel processing

Currently, ethanol is the most important renewable fuel in terms of volume and market value. It is produced from sugar- and starch-based materials such as sugarcane and corn, which is unsustainable. The second generation production of ethanol derived from lignocellulosic materials is now the prime target of biofuel production. Hydrolysis of lignocellulosic materials is the first step for either digestion to biogas (methane) or fermentation to ethanol. Enzymatic hydrolysis of lignocelluloses without pre-treatment is not effective because of the high stability of lignocellulose materials to enzymatic or bacterial attacks. Pre-treatment by physical, chemical or biological means are essential processes for ethanol production from lignocellulosic materials. Pre-treatment enhances the bio-digestibility of the wastes for ethanol and biogas production and increases accessibility of the enzymes to the materials. It results in enrichment of the difficult biodegradable materials, and improves the yield of ethanol or biogas. A detailed understanding of the composition of the lignocellulosic waste is essential to develop and optimize the mechanistic model for its conversion. This model primarily includes pre-treatment processes which help integrate waste streams into the raw materials for ethanol plants, for improved production of ethanol (Taherzadeh and Karimi 2008). This chapter discusses in detail the composition and chemical constituents of the grass cell wall which contributes to agricultural waste residues, a plentiful and sustainable biofuel feedstock. Pre-treatment methods are discussed with a focus on mild acid pre-treatments and scanning electron microscopy analysis (SEM) of post-treatment biomass residuals is reviewed.