利用SEM，XRD和FTIR研究四种化学预处理对楸木木屑酶解的影响

利用 NaOH ，Ca（OH）2，H2 SO4和 HCl 四种溶液对楸木木屑进行化学预处理，发现两种碱预处理均能显著提高楸木木屑的酶解效率。采用扫描电镜（SEM ），X 射线衍射（XRD）和傅里叶红外光谱（FTIR）对四种化学预处理后的楸木木屑进行观察和分析。SEM 观察发现，四种化学预处理对楸木木屑的纤维表面均有不同程度的破坏与侵蚀，其中 Ca（OH）2的破坏效果最为明显。XRD 谱图表明，碱预处理对楸木木屑纤维素的非晶体结构产生破坏，导致其结晶度升高，而经过酸预处理后楸木木屑纤维素的结晶度没有明显变化。FTIR 谱图显示，酸碱预处理对楸木木屑中半纤维素和木质素的分子结构均有不同程度的破坏，碱预处理过程中木质素的高效溶出可能是楸木木屑酶解效率显著提高的主要原因。

Effect of Four Types of Chemical Pretreatment on Enzymatic Hydrolysis by SEM,XRD and FTIR Analysis

Catalpa sawdust was respectively pretreated by NaOH ,Ca(OH )2 ,H2 SO4 and HCl solution ,and the enzymatic hydrolysis of catalpa sawdust was significantly enhanced by alkaline pretreatments .In order to investigate the mechanisms of pretreatment of catalpa sawdust ,the characteristics of catalpa sawdust before and after pretreatments were analyzed by scanning electron microscopy (SEM ) ,X‐ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy .It was found that the surface of catalpa sawdust was disrup‐ted by four kinds of chemical pretreatment ,and the pretreatment with Ca(OH)2 solution resulted in the most serious damage .The XRD results showed that part of amorphous regions was damaged by alkaline pretreat‐ments ,which led to a relative increase of crystallinity Index (CrI) of catalpa sawdust ;while the CrI of catalpa sawdust was insignificantly influenced by acid pretreatments .The FTIR analysis displayed that the molecular structures of hemicellulose and lignin of catalpa sawdust were damaged in different degrees by four types of pretreatment .The significant improvement of enzymatic hydrolysis of catalpa sawdust after alkaline pretreat‐ment might be attributed to the effective delignification of alkaline .