7. Impact of Pretreatment Technologies for Biomass to Biofuel Production

Lignocellulose biomass (LCB) is a sustainable resource and raw materials for various products of human uses (fuel, adhesive, bioplastic, biopolymer, bionanomaterials, phenolics, etc.), biofuel being on the top. LCB however is a complex mass of three very different types of chemicals such as lignin, hemicelluloses, and cellulose. A pretreatment technique is applied to weaken or break the linkages between and within these three components. An ideal pretreatment technology to be used must ensure obtainment of three components from LCB in the purest form, at an affordable cost without concurrent production of any toxic by-products. For the last many decades, extensive works have been carried out with the objective to find out nearly an ideal pretreatment method. As a consequence, a number of pretreatment techniques have been reported that can be grouped into five major classes such as physical, physicochemical, chemical, biological, and nanoscale methods. They have their own pros and cons, and thus search for that ideal technique or improvising an existing one is still going on. In the following section, a critical assessment of the reported techniques under the above said categories and their impact on breaking of recalcitrance of LCB and in turn possible impact on 2G bioethanol technology is given.