采用碱性过氧化氢（AHP）体系对慈竹进行预处理,研究过氧化氢（H2O2）用量对竹材化学组分及酶水解得率的影响。利用X射线衍射（XRD）和傅里叶变换红外光谱仪（FTIR）分析预处理前后物料的物理和化学结构变化,采用二维核磁共振技术研究预处理物料中剩余木质素的化学结构。结果表明：AHP预处理过程中,随着H2O2用量（质量分数）的增加,竹材的葡聚糖含量（相对质量百分比）先增加后减少,木聚糖含量基本不变,而木质素含量整体呈减少趋势。AHP预处理能显著提升竹材的酶解效率,在纤维素酶用量为15 FPU/g葡聚糖,H2O2用量为7.0%时,预处理竹材的酶水解性能最高,葡聚糖和木聚糖酶水解得率分别为93.9%和100%。研究发现,慈竹木质素脱除率在H2O2用量达到2.0%后趋于稳定,为68.8%,继续增加H2O2用量,木质素脱除率无明显提升,对预处理竹材中剩余木质素进行2D-HSQC核磁分析,这部分难以脱除的木质素的化学结构为：64%的S单元、33.7%的G单元和61.6%的β——O——4键,其中S/G值为1.90。
Abstract
This study pretreated bamboo with alkaline hydrogen peroxide （AHP）, the effects of hydrogen peroxide concentration on chemical composition and enzymatic digestibility were investigated. The physical and chemical structural variations of the samples before and after the pretreatment were studied with X-ray diffraction （XRD） and Fourier transform infrared spectroscopy （FT-IR）, and the chemical structure of residual lignins in pretreated bamboo were investigated by 2D-HSQC NMR spectroscopy. The results indicate that in the process of alkaline hydrogen peroxide pretreatment, with the increase of H2O2 dosage, the glucan content of bamboo first increases and then decreases, while the contents of xylan remains basically unchanged, and the lignin content shows a decreasing trend after the AHP pretreatment. The AHP pretreatment improves the enzymatic digestibility of bamboo, and the enzymatic hydrolysis yield reaches the maximum of 93.9% （glucan） and 100% （xylan） when the cellulase dosage is 15 FPU/g glucan and H2O2 dosage is 7.0%. The lignin removal rate plateau at the 2.0% H2O2, with a delignification of ~68% （2.0% H2O2）. The 2D-HSQC NMR was performed to reveal the chemical structure of the residual lignin in the pretreated bamboo sample, it is found that the chemical structure of the undegradable residual lignin contains 64% S units, 33.7% G units and 61.6% β-O-4 bonds with the S/G value of 1.90.
关键词
生物乙醇 /
酶解 /
去木质素 /
木质素结构 /
竹材 /
碱性过氧化氢预处理
Key words
bioethanol /
enzymatic hydrolysis /
delignification /
lignin structure /
bamboo /
alkaline hydrogen peroxide pretreatment
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基金
国家自然科学基金（32001273）; 江苏省生物质能源与材料重点实验室基本科研业务费项目（JSBEM-S-202004）
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