Thermal assisted alkaline pretreatment (TAAP) of rice husk (RH) was investigated to facilitate enzymatic saccharification by enhancing the enzyme accessibility to cellulosic components. Statistically guided experiments based on the Box-Behnken design involving four factors viz. biomass loading, particle size, NaOH loading and reaction time was considered for optimization. The maximum sugar yield of 371 mg g-1 biomass was obtained at optimized pretreatment condition [biomass loading (10% w/w), particle size (0.25-0.625 mm), NaOH loading (2% w/w), and reaction time (40 min)]. The TAAP of RH resulted in the efficient removal of lignin (14.9-54% (w/w)) with low hemicellulose solubilization [10.7-33.1% (w/w)] and with a simultaneous increase in cellulose concentration [32.65-51.65% (w/w)]. The SEM analysis indicated increased porosity and biomass disruption during TAAP. The FTIR analysis showed progressive removal of noncellulosic constituents, and XRD analysis revealed an increase in cellulose crystallinity post-TAAP indicating the effectiveness of pretreatment.
Keywords: Box-Behnken design; Enzymatic saccharification; Lignocellulosic biomass; Rice husk; Thermal assisted alkaline pretreatment.
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