Toward a better understanding of the lignin isolation process from wood
Toward a better understanding of the lignin isolation process from wood
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DOI：
10.1021/jf060722v
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发表时间：
2006-08-09
影响因子：
6.1
通讯作者：
Argyropoulos, Dimitris S.
中科院分区：
文献类型：
--
作者：
Guerra, Anderson;Filpponen, Ilari;Argyropoulos, Dimitris S.
最近开发的分离酶温和酸解木质素（EMAL）的方案，结合衍生化后还原裂解（DFRC）和定量P-31核磁共振波谱的新组合，以更好地了解从木材中分离木质素的过程。EMAL协议被证明提供木质素样品，更能代表木质素整体存在于铣削木材。DFRC/P-31 NMR的结合详细地揭示了分离条件对木质素结构的影响。更具体地说，我们将振动和球磨作为两种木材粉碎方法，并比较了它们对木质素结构和分子量的影响。振动铣削条件引起大量木质素解聚。木质素解聚是通过未凝聚的-芳基醚键的裂解发生的，而凝聚的-芳基醚和二苯二氮杂辛被发现对这种机械作用有抵抗力。振动铣削条件下的缩合反应和侧链氧化反应由缩合的酚羟基和羧酸基团的增加所证明。另外，发现球磨提供的温和机械处理不会影响分离的木质素大分子结构。然而，当机械作用强度较低时，发现整体木质素收率受到损害，需要在球磨条件下延长研磨时间。与从同批次木质素中分离的其他木质素制剂相比，EMAL的产率比相应的木质素（MWL）高4倍，比纤维素水解酶木质素（CEL）高2倍。分子量分布分析还指出，EMAL协议允许分离木质素组分，这是任何其他木质素分离程序无法获得的。
The recently developed protocol for isolating enzymatic mild acidolysis lignins ( EMAL) coupled with the novel combination of derivatization followed by reductive cleavage ( DFRC) and quantitative P-31 NMR spectroscopy were used to better understand the lignin isolation process from wood. The EMAL protocol is shown to offer access at lignin samples that are more representative of the overall lignin present in milled wood. The combination of DFRC/P-31 NMR provided a detailed picture on the effects of the isolation conditions on the lignin structure. More specifically, we have used vibratory and ball milling as the two methods of wood pulverization and have compared their effects on the lignin structures and molecular weights. Vibratory-milling conditions cause substantial lignin depolymerization. Lignin depolymerization occurs via the cleavage of uncondensed beta-aryl ether linkages, while condensed beta-aryl ethers and dibenzodioxocins were found to be resistant to such mechanical action. Condensation and side chain oxidations were induced mechanochemically under vibratory-milling conditions as evidenced by the increased amounts of condensed phenolic hydroxyl and carboxylic acid groups. Alternatively, the mild mechanical treatment offered by ball milling was found not to affect the isolated lignin macromolecular structure. However, the overall lignin yields were found to be compromised when the mechanical action was less intense, necessitating longer milling times under ball-milling conditions. As compared to other lignin preparations isolated from the same batch of milled wood, the yield of EMAL was about four times greater than the corresponding milled wood lignin (MWL) and about two times greater as compared to cellulolytic enzyme lignin (CEL). Molecular weight distribution analyses also pointed out that the EMAL protocol allows the isolation of lignin fractions that are not accessed by any other lignin isolation procedures.