Effects of NH4Cl and MgCl2 on pretreatment and xylan hydrolysis of miscanthus straw

This study investigated the effects of NH4Cl and MgCl2 on pretreatment and xylan hydrolysis of miscanthus straw for biofuels production. It was observed that increasing the pretreatment temperature decreased the remaining solid, increased the enzymatic digestibility, and increased the xylan removal. When 0.2–5.0% NH4Cl and MgCl2 were employed in pretreatments, increasing the inorganic salt concentration slightly diminished the remaining solid, though the enzymatic digestibility was enhanced. Under the higher-than-2% condition, no xylan remained in the solid residues after pretreatment. With pretreatment time, the remaining solid slightly decreased, but the enzymatic digestibility was increased. Moreover, xylan removal was linearly increased to 15 min, after which it was completely hydrolyzed. Overall, these results indicated that pretreatment by 2% NH4Cl or MgCl2 at 185 °C for 15 min completely hydrolyzes the xylan of miscanthus straw. In scanning electron microscopy (SEM) images, the physical surface of the miscanthus straw showed an apparently damaged surface area and exposure of the internal structure after pretreatment with NH4Cl and MgCl2 by SEM.