A comparative evaluation of agave bagasse in function of autohydrolysis, AFEX and ionic liquid pretreatment

Production of fuels derived from biomass offers the only renewable liquid alternative to petroleum-based transportation fuels. One of the largest obstacle to economical production of cellulosic biofuels is cost-effectively releasing sugars from recalcitrant biomass through pretreatment and downstream fermentation while preserving a sustainable process. Currently, the main source of biorenewable energy has been corn stover, sugarcane bagasse, switchgrass and woody biomass. Agave bagasse (AGB - byproduct of Tequila industry) has demonstrated recently its potential as a biofuel feedstock that can produce high saccharification kinetics and sugar yields. This study aims to assess the first direct side-by-side comparative analysis in AGB using autohydrolysis (AH), ammonia fiber expansion (AFEX^TM) and ionic liquid (IL) pretreatments on their respective impacts on biomass structure, composition, process mass balance, and enzymatic saccharification efficiency. The pretreatments were performed using the following conditions for AH (180 °C/30 min), AFEX^TM (120 °C/38 min) and IL (120 °C/180 min) using water, ammonia and [C₂mim][OAc], respectively. All experiments were performed using a 10% biomass loading, and subsequent enzymatic saccharification with a normalized enzyme loading per gram of glucan. Pretreated biomass materials were characterized to obtain their crystallinity index by powder X-ray diffraction (XRD), chemical fingerprint by Fourier transform infrared spectroscopy (FTIR), structural identification and S/G ratios in lignin groups by two-dimensional nuclear magnetic resonance (2D-NMR) spectroscopy using heteronuclear single quantum coherence (HSQC), and wet-chemistry techniques.

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