【作者】 路祺；

【导师】 祖元刚；

【作者基本信息】 东北林业大学 ， 植物学， 2011， 博士

【摘要】 刺五加根茎主要成分为纤维素和木质素,经过中药提取后产生大量刺五加根茎剩余物,本论文以中药提取(刺五加根茎)剩余物为原料,分别采用四种有机溶剂法提取木质素即高沸醇法(1,4-丁二醇法)、乙醇法、丙酮法和乙酸法,以提高木质素的抗氧化能力为主要考察指标,并通过正交实验对工艺条件进行了优化,制备得到了四种优化有机木质素,采用1H-NMR、FTIR、DSC、TG、元素分析、官能团检测和凝胶色谱等手段对四种有机木质素和碱法木质素的性质进行了表征,抗氧化能力差异进行了比较分析。采用五轴图方式对四种有机木质素和碱法木质素的综合抗氧化能力进行了分析比较。通过引入木质素提取效率概念,对四种优化方法进行了有机木质素提取效率分析评价,借助超临界反溶剂技术(SAS),以木质素微粉粒径大小为考察指标,对有机木质素进行微粉化研究,通过正交实验对工艺条件进行了优化。结果表明:1)高沸醇法制备木质素正交实验优化结果为:共溶剂乙酸浓度固定为10%时,反应温度为200℃,反应时间为80min,料液比为1:10,高沸醇浓度为80%。所得木质素抗氧化能力EC50DPPH值为0.808mg/mL,在此条件下木质素得率为15.02%,木质素含量为 85.38%。乙醇法制备木质素正交实验优化结果为:共溶剂乙酸浓度固定为10%时,反应温度为180℃,反应时间为80min,料液比为1:20,乙醇浓度为80%。所得木质素抗氧化能力EC50DPPH值为1.020mg/mL,在此条件下木质素得率为9.68%,木质素含量89.75%。丙酮法制备木质素正交实验优化结果为:共溶剂乙酸固定为10%时,反应温度为180℃,反应时间为80min,料液比为1:20,丙酮浓度为80%。所得木质素抗氧化能力EC50DPPH值为1.519mg/mL,在此条件下木质素得率为7.39%,木质素含量83.91%。乙酸法制备木质素正交实验优化结果为:反应温度200℃,反应时间60min,料液比1:10,乙酸浓度60%。所得木质素抗氧化能力EC50DPPH值为0.563mg/mL,在此条件下木质素得率为18.67%,木质素含量91.18%。2)通过对木质素进行元素分析,发现丙酮法木质素、乙醇法木质素、高沸醇法木质素和乙酸法木质素的碳含量和氢含量依次降低,而氧含量是依次增加。另外碱法木质素中含有少量氮元素和硫元素;凝胶色谱(GPC)分子量检测结果表明五种木质素的重均分子量(Mw)从大到小排序为:高沸醇法木质素>乙酸法木质素>乙醇法木质素>丙酮法木质素>碱法木质素;TG-DSC趋势表明热解过程有三个阶段存在,丙酮法木质素第二个阶段较高沸醇法木质素更为明显;通过对有机木质素和碱法木质素官能团含量测定,结果发现乙酸法木质素的酚羟基和羧基含量最高。采用五轴图对四种有机木质素、碱法木质素进行抗氧化能力综合评价。依据相对面积比值大小,得出各种木质素综合抗氧化能力排序为:乙酸法木质素>高沸醇法木质素>乙醇法木质素>丙酮法木质素>碱法木质素。通过对四种有机溶剂法木质素提取效率分析,四种有机溶剂法木质素提取效率从高到低的顺序为:高沸醇法>乙酸法>乙醇法>丙酮法。3)超临界反溶剂法(SAS)微粉化有机木质素正交实验优化结果为:沉淀反应釜温度35℃,沉淀反应釜压力30MPa,温度差+10℃,木质素溶液浓度0.5mg/mL。得到粒径为0.144±0.03μm的有机木质素微粉;微粉化前、后样品木质素含量的检测结果表明微粉过程对有机木质素含量变化没有影响;通过扫描电镜图可以明显看出微粉化的有机木质素呈现小球形;SAS微粉化前、后木质素的红外光谱图和1H-NMR谱图分析表明木质素结构没有变化;从TG-DSC趋势图可知SAS微粉化后的有机木质素有较高热重损失;微粉化前、后有机木质素的XRD图可以看出两种木质素都是无定形聚合物形态;气相色谱分析表明SAS微粉后有机木质素样品中没有检测到丙酮残留;通过体外溶解度实验,微粉化后有机木质素的溶解度有很大的提高,24小时大约有31%的微粉化有机木质素溶解,微粉化前的有机木质素仅有2.5%的溶解。另外,微粉化后有机木质素在120min之内达到溶解平衡,而未微粉化有机木质素超过了 240min。微粉化前、后有机木质素DPPH去除能力EC50值分别为0.884±0.02mg/mL和0.552±0.01mg/mL。通过总还原能力对比,发现微粉化后木质素总还原能力要明显高于微粉化前的有机木质素;微粉化前、后有机木质素木质素对超氧自由基去除能力EC50值分别为0.903±0.18mg/mL和0.581±0.015mg/mL。SAS法微粉化后的有机木质素超氧自由基去除能力高于微粉化前的有机木质素。更多还原

【Abstract】 Acanthopanax Senticosus(AS)is a typical oriental medicinal herb.After roots and stems of AS were extracted by ethanol,a large quantity of AS remainder,which contains a lot of cellulose,hemicellulose and lignin,is usually abandoned.Thus,the AS remainder has a huge potential application value as the cellulose materials.The objective of this study is to evaluate the antioxidative property of lignin by four organosolv pulping methods,such as high boiling solvent(1,4-butanediol)(HBS)method,ethanol method,acetone method and acetic acid method,comparing with kraft method.Four factors,namely reaction temperature,reaction time,solid-liquid ratio and organic solvent concentration,were studied by evaluating free radical scavenging effect and optimized by a four-level orthogonal array design.The four organic solvent method lignins under optimal conditions and kraft lignin was characterized by nuclear magnetic resonance(1H-NMR),fourier-transform infrared spectroscopy(FTIR),element analysis,gel permeation chromatography(GPC),differential scanning calorimeters(DSC),thermogravimetry(TG),the amount of lignin functional groups and antioxidative property.Antioxidant activities of various lignins against DPPH radical,superoxide radical,total phenolic content,reducing power and ferric reducing antioxidant power were evaluated and characterized comprehensively by the area framed the chart line in 5-axe cobweb charts.Therefore,we adopted the delignification efficiency to exactly evaluate the feasibility of these pulping methods in this research.Lignin extraction efficiencies from different organosolv methods were compared.Lignin was micronized by supercritical antisolvent process(SAS).The four factors of micronized lignin were studied and optimized by a four-level orthogonal array design.1)The HBS method were studied and optimized by a four-level orthogonal array design.The optimal conditions are as follows:under the condition of acetic acid concentration fixed to 10%,reaction temperature 200℃,reaction time 80min,solid-liquid ratio 1:10,1,4-butanediol concentration 80%.Under the optimal conditions,HBS lignin antioxidant activities against DPPH radical,lignin yield and lignin concentration are 0.808mg/mL(EC50),15.02%and 85.38%,respectively.The ethanol method were studied and optimized by a four-level orthogonal array design.The optimal conditions are as follows:under the condition of acetic acid concentration fixed to 10%,reaction temperature 180℃,reaction time 80min,solid-liquid ratio 1:20,ethanol concentration 80%.Under the optimal conditions,ethanol lignin antioxidant activities against DPPH radical,lignin yield and lignin concentration are 1.02mg/mL(EC50),9.68%and 89.75%,respectively.The acetone method were studied and optimized by a four-level orthogonal array design.The optimal conditions are as follows:under the condition of acetic acid concentration fixed to 10%,reaction temperature 180℃,reaction time 80min,solid-liquid ratio 1:20,acetone concentration 8 0%.Under the optimal conditions,acetone lignin antioxidant activities against DPPH radical,lignin yield and lignin concentration are 1.519mg/mL(EC50),7.39%and 83.91%,respectively.The acetic acid method were studied and optimized by a four-level orthogonal array design.The optimal conditions are as follows:reaction temperature 200℃,reaction time 60min,solid-liquid ratio 1:10,acetone concentration 60%.Under the optimal conditions,acetone lignin antioxidant activities against DPPH radical,lignin yield and lignin concentration are 0.563mg/mL(EC50),18.67%and 91,18%,respectively.2)The elemental analysis results of lignin samples are shown that contents of carbon and hydrogen decreased and oxygen content increased from acetone,ethanol,1,4-butanediol to acetic acid lignins.There were nitrogen and sulfur element in the KL,but no in the four organosolv lignins;The molecular weight distribution of organosolv lignins,as revealed by GPC analysis,showed a bimodal mode.The weight average molecular weight(Mw)of the five lignins decreased in the order:HBS lignin>acetic acid lignin>ethanol lignin>acetone lignin>KL.Due to mild reaction conditions,HBS lignin has more Mw and near to natural lignin than other lignin;TG-DSC analysis results showed three steps during samples degradation.The degradation peaks were more pronounced at second step for the acetone than 1,4-butanediol lignin;Through the functional testing,the phenolic hydroxyl and carboxylic acid contents of the acetic acid lignin were highest in this study lignin samples.The antioxidant activity analysis results showed acetic acid lignin had the highest general antioxidant capacity among all the lignins,and corroborated well with the results of other antioxidant capacity assay by 5-axe cobweb charts(including DPPH,RP,FRAP,SRAS and TP).The HBS(1,4-butanediol)method had the highest delignification efficiency in these pulping methods.The delignification efficiency decreased in the order:HBS method>acetic acid method>acetone method>ethanol method.3)The supercritical antisolvent(SAS)process were studied to prepare nanoscale lignin and optimized by a four-level orthogonal array design.The optimal conditions are as follows:precipitation temperature 35℃,precipitation pressure 30 MPa,temperature difference+10℃and concentration of lignin solution 0.5mg/mL.Under the optimal conditions,micronized lignin with mean particle size of 0.144±0.03μm was obtained.The SEM image of nanoscale lignin demonstrates that very small spherical nanoparticles are obtained by SAS.The non-nanoscale lignin owns irregular shapes and unevenly size distribution,with a length ranging from 1 to 100μm.Significant differences lied in the morphology and mean particle size of the nanoscale and non-nanoscale lignin;the lignin content after nanoscale and non-nanoscale lignin was detected by using the APPITA Plls-78 method.From the result we can see there was little change in the lignin content before and after micronizated process;The SEM imagedemonstrates that very small spherical nanoparticles were obtained in verification test of nanoscale lignin under the optimal condition;In the FTIR spectra and 1H NMR,the results indicated that the structure of non-nanoscale and nanoscale lignin had no significant difference and no degradation occurred after SAS process;The TG-DSC results showed that nanoscale lignin had higher weight loss than non-nanoscale lignin;In XRD figure,diffused pattern demonstrates that lignin was an amorphous polymer;There was no characteristic peak of acetone in GC chromatogram of nanoscale lignin;Comparing with the non-nanoscale lignin,the solubility of the nanoscale lignin was highly increased,about 31%of nanoscale lignin sample dissolved,while only 2.5%of non-nanoscale lignin dissolved after 24h.Furthermore,nanoscale lignin reached dissolution equilibrium within 120min,but it took over 240min for the non-nanoscale lignin to do so.The EC50 of the nanoscale and non-nanoscale lignin on DPPH was 0.552±0.01mg/mL and 0.884±0.02mg/mL,respectively.The nanoscale lignin had stronger ferric reducing ability than the non-nanoscale lignin.The superoxide radical scavenging activity of non-nanoscale lignin was found to be lower than that of nanoscale lignin;the EC50 of nanoscale and non-nanoscale lignin was 0.581±0.015mg/mL and 0.903±0.18mg/mL,respectively.更多还原