Application of hydrogen peroxide presoaking prior to ammonia fiber expansion pretreatment of energy crops

This work presents the application of ammonia fiber expansion (AFEX) pretreatment both with (H-AFEX) and without hydrogen peroxide presoaking of energy crops moso bamboo, giant reed, and Miscanthus. The influences of AFEX and H-AFEX pretreatments on chemical composition and enzymatic hydrolysis were assessed. The results address the solid recovery, delignification, hydrolysis sugar yields, and micro-structural morphology of varying H-AFEX pretreatment conditions of energy crops. A strong negative correlation between solid recovery and H2O2 loading was found for all pretreated samples with H2O2 loading <2.0. In comparison with AFEX process, the addition of hydrogen peroxide in H-AFEX pretreatment could result in increases in glucose yields at the expense of xylose. The maximum sugar yields of moso bamboo, giant reed, and Miscanthus were 269.0, 424.6, and 485.0 g per kg dry biomass respectively, which were obtained under their optimal pretreatment conditions following enzymatic hydrolysis. The micrograph of H-AFEX-treated giant reed demonstrated that the modified porous structure resulted in increased enzyme accessible surface area, and facilitated the subsequent enzymatic hydrolysis.