Kyeong Eop Kang

Effects of inorganic salts on pretreatment of Miscanthus straw

This study focused on the effects of five inorganic salts, NaCl, KCl, CaCl2, ZnCl2, and FeCl3, on the pretreatment of Miscanthus straw for sugar recovery and enzymatic digestibility. In the results, all of the salts reduced the hemicellulose content in the straw. Most notably, FeCl3 effected almost 100% xylan removal. Overall, the trivalent salts, which include FeCl3, had an especially significant influence on enzymatic digestibility of Miscanthus straw compared with the di- and mono-valent inorganic salts, which had relatively only minor effects. The salt impacts were in the following order: FeCl3>ZnCl2>CaCl2>KCl>NaCl. Under the pretreatment condition of 0.5% FeCl3 at 200°C for 15min, 100% xylan removal and 71.6% enzymatic digestibility were obtained. Nevertheless, ZnCl2 get the better effect on total glucose content than that of FeCl3.

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

This study investigated the effects of NH(4)Cl and MgCl(2) 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% NH(4)Cl and MgCl(2) 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% NH(4)Cl or MgCl(2) 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 NH(4)Cl and MgCl(2) by SEM.