The effect of the severity of an organosolv treatment of Miscanthus x giganteus on antioxidant capacity of the obtained lignin was studied. Four organosolv lignins extracted with different severity conditions were cho...The effect of the severity of an organosolv treatment of Miscanthus x giganteus on antioxidant capacity of the obtained lignin was studied. Four organosolv lignins extracted with different severity conditions were chosen and tested. Results obtained using the methyl linoleate method have shown a correlation between oxygen uptake index and the combined severity. It was found that lignin extracted at higher severity pre-treatment and with a higher phenolic hydroxyl content, lower aliphatic hydroxyl content, molecular weight and polydispersity has the highest antioxidant capacity.展开更多
A newly isolated bacterium was screened out for its survival on medium with 6 000 mg/L kraft lignin as the sole carbon source and energy,and identified as Pandoraea sp.by 16S rRNA gene sequence analysis.The biodegrada...A newly isolated bacterium was screened out for its survival on medium with 6 000 mg/L kraft lignin as the sole carbon source and energy,and identified as Pandoraea sp.by 16S rRNA gene sequence analysis.The biodegradation experiment was carried out in mineral salt medium,containing 5 000 mg/L kraft lignin as only carbon and energy at pH 8.0 and 30 °C.Under these conditions,significant reduction in color and lignin content by the strain was observed after incubation for 5 d.The strain attains maximum reduction capability in color(44.6%) and lignin content(39.9%) within 5 d of incubation,and reduced chemical oxygen demand(COD) from initial concentration 7 399 to 3 980 mg/L at maximum reduction level of 46.2% on the 4th day.The total ion chromatograph(TIC) of compounds presented in the chloroform extract of control and bacterial treated samples shows the formation of several lignin-related aromatic compounds including some small molecular lignin fragments,indicating a strong destruction in the lignin structure.展开更多
紫丁香基木质素是一种重要的木质素,天然木质素也大多通过β-O-4键连接成网状结构,β-O-4型紫丁香基木质素二聚体模化物在前人研究的模化物基础上增加了多个甲氧基基团,更接近实际的紫丁香基木质素结构。在软件Materials Studio 2019的D...紫丁香基木质素是一种重要的木质素,天然木质素也大多通过β-O-4键连接成网状结构,β-O-4型紫丁香基木质素二聚体模化物在前人研究的模化物基础上增加了多个甲氧基基团,更接近实际的紫丁香基木质素结构。在软件Materials Studio 2019的Dmol3模块中,基于密度泛函理论利用B3LYP杂化泛函,对β-O-4型紫丁香基木质素二聚体模化物在875K、101kPa条件下的热解反应路径进行模拟,计算每步反应的反应物与生成物的焓值,并通过Vibration Analysis模块进行频率分析确认只有实频,没有虚频;计算每步反应的焓变并对反应路径总焓变进行比较,总焓变越小表明该路径在热力学上越容易发生,进而得到其较具优势的反应路径,最终得到对应路径的热解产物。结果表明,β-O-4型紫丁香基木质素二聚体模化物在875K、101kPa下的初步热解较有可能发生C_(α)—C_(β)键的断裂与β-O-4键的断裂,其中最可能发生β-O-4键的断裂;较具优势的反应路径包括总焓变为-59.65kJ/mol的R4、总焓变为-219.44 kJ/mol的R10、总焓变为-14.93kJ/mol的R12、总焓变为-389.29kJ/mol的R21、总焓变为-466.24kJ/mol的R23与总焓变为-276.72kJ/mol的R24,其中最具优势的路径为R21、R23与R24;热解的主要产物是邻苯三酚、3,4,5-三羟基苯甲醇、3,4,5-三羟基苯甲醛及乙醇,其中邻苯三酚、3,4,5-三羟基苯甲醇与乙醇为R21、R23与R24的热解产物。本研究得到的模拟结果可以为生成生物质焦的进一步模拟计算奠定基础。展开更多
分子量是聚合物的重要特性之一,木质素的分子量及其分布是研究苯丙烷类结构的反应、物理化学特性和评价其改性产物质量的内容之一。本研究以陆地棉TM-1成熟纤维为材料,分别利用酶解-温和酸解木质素法和二氧六环法提取棉纤维中木质素,结...分子量是聚合物的重要特性之一,木质素的分子量及其分布是研究苯丙烷类结构的反应、物理化学特性和评价其改性产物质量的内容之一。本研究以陆地棉TM-1成熟纤维为材料,分别利用酶解-温和酸解木质素法和二氧六环法提取棉纤维中木质素,结合凝胶渗透色谱法(gel permeation chromatography,GPC)调查和评价2种方法获得的棉纤维中木质素的相对分子量。结果表明,经二氧六环处理提取的棉花纤维中的木质素(dioxane lignin,DL)的重均分子量为2924g mol^(–1)、数均分子量2403 g mol^(–1),略高于由酶解-温和酸解处理提取的木质素(enzymatic hydrolysis-mild acidolysis lignin,EMAL)的重均分子量(2169 g mol^(–1))和数均分子量(1970 g mol^(–1)),EMAL的多分散系数稍低,说明木质素的均一性比DL高。表明EMAL法提取的木质素更适用于分析棉纤维中木质素的相对分子量。利用EMAL法分析棉纤维中木质素相对分子量表明,不同棉花品种的木质素重均分子量分布范围为938~2169 g mol^(–1),数均分子量分布范围为857~1970 g mol^(–1),多分散性系数在1.09~1.74间,均小于2。重均分子量与纤维马克隆值呈显著负相关,数均分子量与纤维长度呈显著负相关,与纤维马克隆值呈极显著负相关。展开更多
文摘The effect of the severity of an organosolv treatment of Miscanthus x giganteus on antioxidant capacity of the obtained lignin was studied. Four organosolv lignins extracted with different severity conditions were chosen and tested. Results obtained using the methyl linoleate method have shown a correlation between oxygen uptake index and the combined severity. It was found that lignin extracted at higher severity pre-treatment and with a higher phenolic hydroxyl content, lower aliphatic hydroxyl content, molecular weight and polydispersity has the highest antioxidant capacity.
基金Project(50925417) supported by the National Funds for Distinguished Young Scientists,ChinaProject(50830301) supported by the Key program of the National Natural Science Foundation of ChinaProject(2012BAC12B03) supported by the National 12th Five-year Plan for Science and Technology Support,China
文摘A newly isolated bacterium was screened out for its survival on medium with 6 000 mg/L kraft lignin as the sole carbon source and energy,and identified as Pandoraea sp.by 16S rRNA gene sequence analysis.The biodegradation experiment was carried out in mineral salt medium,containing 5 000 mg/L kraft lignin as only carbon and energy at pH 8.0 and 30 °C.Under these conditions,significant reduction in color and lignin content by the strain was observed after incubation for 5 d.The strain attains maximum reduction capability in color(44.6%) and lignin content(39.9%) within 5 d of incubation,and reduced chemical oxygen demand(COD) from initial concentration 7 399 to 3 980 mg/L at maximum reduction level of 46.2% on the 4th day.The total ion chromatograph(TIC) of compounds presented in the chloroform extract of control and bacterial treated samples shows the formation of several lignin-related aromatic compounds including some small molecular lignin fragments,indicating a strong destruction in the lignin structure.
文摘紫丁香基木质素是一种重要的木质素,天然木质素也大多通过β-O-4键连接成网状结构,β-O-4型紫丁香基木质素二聚体模化物在前人研究的模化物基础上增加了多个甲氧基基团,更接近实际的紫丁香基木质素结构。在软件Materials Studio 2019的Dmol3模块中,基于密度泛函理论利用B3LYP杂化泛函,对β-O-4型紫丁香基木质素二聚体模化物在875K、101kPa条件下的热解反应路径进行模拟,计算每步反应的反应物与生成物的焓值,并通过Vibration Analysis模块进行频率分析确认只有实频,没有虚频;计算每步反应的焓变并对反应路径总焓变进行比较,总焓变越小表明该路径在热力学上越容易发生,进而得到其较具优势的反应路径,最终得到对应路径的热解产物。结果表明,β-O-4型紫丁香基木质素二聚体模化物在875K、101kPa下的初步热解较有可能发生C_(α)—C_(β)键的断裂与β-O-4键的断裂,其中最可能发生β-O-4键的断裂;较具优势的反应路径包括总焓变为-59.65kJ/mol的R4、总焓变为-219.44 kJ/mol的R10、总焓变为-14.93kJ/mol的R12、总焓变为-389.29kJ/mol的R21、总焓变为-466.24kJ/mol的R23与总焓变为-276.72kJ/mol的R24,其中最具优势的路径为R21、R23与R24;热解的主要产物是邻苯三酚、3,4,5-三羟基苯甲醇、3,4,5-三羟基苯甲醛及乙醇,其中邻苯三酚、3,4,5-三羟基苯甲醇与乙醇为R21、R23与R24的热解产物。本研究得到的模拟结果可以为生成生物质焦的进一步模拟计算奠定基础。
文摘分子量是聚合物的重要特性之一,木质素的分子量及其分布是研究苯丙烷类结构的反应、物理化学特性和评价其改性产物质量的内容之一。本研究以陆地棉TM-1成熟纤维为材料,分别利用酶解-温和酸解木质素法和二氧六环法提取棉纤维中木质素,结合凝胶渗透色谱法(gel permeation chromatography,GPC)调查和评价2种方法获得的棉纤维中木质素的相对分子量。结果表明,经二氧六环处理提取的棉花纤维中的木质素(dioxane lignin,DL)的重均分子量为2924g mol^(–1)、数均分子量2403 g mol^(–1),略高于由酶解-温和酸解处理提取的木质素(enzymatic hydrolysis-mild acidolysis lignin,EMAL)的重均分子量(2169 g mol^(–1))和数均分子量(1970 g mol^(–1)),EMAL的多分散系数稍低,说明木质素的均一性比DL高。表明EMAL法提取的木质素更适用于分析棉纤维中木质素的相对分子量。利用EMAL法分析棉纤维中木质素相对分子量表明,不同棉花品种的木质素重均分子量分布范围为938~2169 g mol^(–1),数均分子量分布范围为857~1970 g mol^(–1),多分散性系数在1.09~1.74间,均小于2。重均分子量与纤维马克隆值呈显著负相关,数均分子量与纤维长度呈显著负相关,与纤维马克隆值呈极显著负相关。
