硫酸盐浆残余木素在漆酶/介体体系中的降解(英文)

Degradation of Residual Lignin in Kraft Pulp by Laccase and Mediator System

桉木硫酸盐浆 (EMCC浆 )用漆酶 /介体 (N 羟基 N 乙酰苯胺 )体系 (LMS)进行处理 .采用GPC、FTIR和 2D13C_1H_NMR技术分析了原浆木素、LMS处理过的浆中残余木素以及E段废液中分离出来的木素 ,并在碱性条件下用硝基苯氧化上述木素 .实验结果表明 ,LMS处理后桉木EMCC浆中残余木素发生很大的变化 ,大多数非缩合的木素结构单元被降解 .NMR研究结果表明 ,LMS处理的浆中木素和E段废液木素的β O 4和β 5结构消失 ,紫丁香基结构的信号大大减弱 ,而木素中二苯乙烯结构、二苯甲烷结构和非酚型的 5_5’结构在LMS生物处理时比较稳定 ,难于降解 .LMS处理时木素发生α 位羟基的氧化产生α 羰基 ,并在其后的碱处理段被降解成小分子量的碎片 .纸浆残余木素经漆酶 /介体体系处理发生一定的苯环开环作用 ,使木素的羧基增加 .

Eucalyptus EMCC pulp was treated with laccase and N_acetyl_N_hydroxyl_aniline system. The residual lignin from the original pulp and the LMS treated pulp, as well as lignin isolated from the E_stage effluent, were prepared, then analyzed using GPC, FTIR and 2D 13 C_ 1H_NMR techniques, and oxidized by nitrobenzene in the alkaline condition. The results indicated that the structure of residual lignin undertook a lot of changes in the eucalyptus EMCC pulp after LMS treatment, most of noncondensed substructures of lignin were degraded. The NMR studies showed the disappearance of β _O_4 and β _5 bonds in the structure of residual lignin from LMS treated pulp and the lignin from E_stage effluent, and the signal strength of syringyl structure decreased greatly. Stilbene, dibenzene methane and non_phenolic 5_5' type substructures in lignin were stable to LMS treatment, and difficult to be degraded. During the LMS treatment, α _carbon with hydroxyl group in lignin was subjected to oxidize to α _carbonyl, which can be degraded by alkaline extraction to fragment with small molecular weight; open reaction of benzene ring also took place to form more carboxyl groups in residual lignin.