亚氯酸钠和氢氧化钠两步预处理杨木制备低聚木糖和单糖

doi:10.3969/j.issn.0253-2417.2021.05.004

摘要/Abstract

摘要：

以杨木为研究对象，考察了亚氯酸钠(SC)和氢氧化钠(SH)两步预处理对杨木组成的影响，探讨了酶法制备低聚木糖(XOS)和单糖的特性。研究结果表明：亚氯酸钠预处理能选择性地脱除杨木木质素，杨木经质量分数6%的亚氯酸钠在70℃下处理3 h，木质素移除率达到65.8%，葡聚糖和木聚糖的保留率分别为90.7%和92.4%。X射线衍射和X射线光电子能谱仪分析表明，亚氯酸钠预处理移除了底物中的总木质素和表面的木质素，提高了底物结晶度，增加了底物的可及性。杨木经70℃的亚氯酸钠和50℃的氢氧化钠预处理后，葡聚糖质量分数为67.8%，木聚糖的质量分数为21.5%，木质素质量分数为2.9%。固体残渣经木聚糖酶水解后低聚木糖得率达到47.2%，其中木二糖占低聚木糖总量的98%以上。与单独亚氯酸钠预处理(6%，70℃，3 h)相比，氢氧化钠预处理将低聚木糖得率提升了7.1倍。经过木聚糖酶水解后，两步预处理的杨木残渣经30 mg/g的纤维素酶(以底物质量计)水解，葡萄糖得率高达90.2%。最终，1 kg杨木可获得52.5 g的低聚木糖、317.6 g葡萄糖和49.9 g木糖。

关键词: 杨木, 亚氯酸钠, 氢氧化钠, 低聚木糖, 酶水解

Abstract:

In this work, the effects of sodium chlorite(SC) and sodium hydroxide(SH) pretreatments on the chemical composition of poplar were investigated. The preparation of xylooligosaccharides(XOS) and monosaccharides by enzymatic hydrolysis was discussed. The results showed that poplar lignin could be selectively removed by SC pretreatment. After 6% SC pretreatment at 70℃ for 3 h, the removal of lignin reached 65.8%, whereas 90.7% glucan and 92.4% xylan were retained. The data of X-ray diffraction and X-ray photoelectron spectroscopy indicated that SC pretreatment removed the total lignin in poplar and the surface lignin on poplar, and increased the crystallinity and accessibility of the substrate. After the pretreatment with 6% SC at 70℃ and 1% SH at 50℃, the contents of glucan, xylan, and lignin in the pretreated poplar were 67.8%, 21.5%, and 2.9%, respectively. The highest XOS yield of 47.2% from the SC-SH-pretreated poplar by xylanase hydrolysis was obtained, and the XOS preparation was composed of 98% xylobiose. Compared with the poplar treated by 6% SC at 70℃ for 3 h, SH pretreatment increased the yield of XOS by 7.1 times. After the hydrolysis by xylanase, the glucose yield of two-step pretreated poplar residue was 90.2% with a cellulase lading of 30 mg/g dry matter. Finally, 52.5 g XOS, 317.6 g glucose and 49.9 g xylose were obtained from 1 kg raw poplar. The results of this work provided a theoretical guidance for the preparation of XOS and monosaccharides from poplar under mild conditions.

Key words: poplar, sodium chlorite, sodium hydroxide, xylooligosaccharides, enzymatic hydrolysis

中图分类号:

TQ35

方鑫, 文沛瑶, 徐勇, 张军华. 亚氯酸钠和氢氧化钠两步预处理杨木制备低聚木糖和单糖[J]. 林产化学与工业, 2021, 41(5): 23-30.

Xin FANG, Peiyao WEN, Yong XU, Junhua ZHANG. Production of Xylooligosaccharides and Monosaccharides from Poplar by Two-step Sodium Chlorite and Sodium Hydroxide Pretreatment[J]. Chemistry and Industry of Forest Products, 2021, 41(5): 23-30.

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参考文献 17

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样品 samples	预处理时间/h pretreatment time	葡聚糖/% glucan	木聚糖/% xylan	木质素/% lignin	乙酰基/% acetyl	固形物回收率/% solid recovery	移除率removal rate/%
样品 samples	预处理时间/h pretreatment time	葡聚糖/% glucan	木聚糖/% xylan	木质素/% lignin	乙酰基/% acetyl	固形物回收率/% solid recovery	葡聚糖 glucan	木聚糖 xylan	木质素 lignin
未处理untreated		40.0±0.8	17.8±0.6	28.0±0.6	4.0±1.0	100.0	0.0	0.0	0.0
SC_0.5	0.5	40.9±0.9	17.7±0.1	22.9±0.4	4.2±0.9	89.0±1.1	8.9	11.4	27.4
SC₁	1	42.5±0.5	18.9±0.4	20.5±0.4	4.2±1.7	87.0±0.8	7.6	7.7	36.3
SC₃	3	42.9±1.4	19.4±0.2	11.3±0.5	4.2±0.9	84.6±0.7	9.3	7.6	65.8

样品 samples	氧碳比 O/C	C/%			结晶度/% crystallinity(I_Cr)	最大吸附量/(mg·g^-1) maximum adsorption (Γ_{max, DR28})
样品 samples	氧碳比 O/C	C—C/C—H	C—O	C＝O/O—C—O	结晶度/% crystallinity(I_Cr)	最大吸附量/(mg·g^-1) maximum adsorption (Γ_{max, DR28})
未处理untreated	0.34±0.0	49.3±1.2	40.4±0.8	10.3±1.0	51.2±0.9	240.4
SC_0.5	0.53±0.0	20.2±0.9	47.2±1.1	32.6±0.7	55.0±1.6	259.3
SC₁	0.55±0.0	36.6±0.9	48.0±1.0	15.4±1.0	56.4±1.5	355.1
SC₃	0.45±0.0	67.2±1.3	22.5±1.9	10.3±0.8	56.5±0.6	566.5

样品 samples	葡聚糖 glucan	木聚糖 xylan	木质素 lignin	乙酰基 acetyl	固形物回收率 solid recovery	移除率removal
样品 samples	葡聚糖 glucan	木聚糖 xylan	木质素 lignin	乙酰基 acetyl	固形物回收率 solid recovery	葡聚糖 glucan	木聚糖 xylan	木质素 lignin
SC_0.5-SH	57.0±0.8	20.2±0.1	10.6±0.4	0	69.3±1.1	3.4	21.1	67.9
SC₁-SH	64.0±0.4	21.4±0.4	4.7±0.2	0	65.8±0.1	0.8	25.5	85.4
SC₃-SH	67.8±1.2	21.5±0.2	2.9±0.5	0	61.4±0.3	2.9	32.0	84.2

样品 samples	低聚木糖得率yield of xylooligosaccharides/%					总得率/% total yield	木糖与低聚木糖质量比值 mass ratio of xylose and XOS
样品 samples	木二糖 xylobiose	木三糖 xylotriose	木四糖 xylotetraose	木五糖 xylopentaose	木六糖 xylohexaose	总得率/% total yield	木糖与低聚木糖质量比值 mass ratio of xylose and XOS
SC_0.5	0.40±0.00	0.16±0.02	0.26±0.00	0.08±0.00	0.16±0.00	1.06±0.07	0.03
SC₁	0.42±0.01	0.33±0.00	0.62±0.01	0.20±0.01	0.03±0.00	1.60±0.09	0.42
SC₃	2.06±0.05	0.83±0.00	1.49±0.12	0.62±0.00	0.85±0.02	5.85±0.23	0.33
SC_0.5-SH	41.00±0.06	0.42±0.01	0.11±0.00	0.04±0.00	0.05±0.00	41.62±1.56	0.19
SC₁-SH	43.19±0.54	0.37±0.02	0.07±0.01	0.05±0.00	0.06±0.00	43.74±1.02	0.17
SC₃-SH	46.97±0.12	0.05±0.00	0.07±0.00	0.05±0.00	0.06±0.00	47.20±0.74	0.20

样品 samples	酶用量/(mg·g^-1) cellulase	葡萄糖得率/% glucose yield	木糖得率/% xylose yield
SC_0.5-SH	10	41.1±0.2	12.1±0.4
SC_0.5-SH	30	81.4±0.1	28.5±0.4
SC₁-SH	10	55.5±0.1	20.0±0.9
SC₁-SH	30	84.0±0.7	32.1±0.8
SC₃-SH	10	64.7±0.5	22.4±0.3
SC₃-SH	30	90.2±1.1	35.3±0.9