【作者】 李少阳；

【导师】 孙润仓； 苏印泉；

【作者基本信息】 西北农林科技大学 ， 野生动植物保护与利用， 2009， 硕士

【摘要】 在能源紧缺与环境保护的双重压力下,生物质能的开发利用引起了人们的广泛关注。苹果树作为经济树种之一,面积陕西居全国之首,每年的修剪量很大,而这些枝条、树干又往往作为传统的薪材低效率的直接燃烧,造成该资源的利用极不科学合理;或者长期堆放腐朽作为肥料使用,致使枝条内潜在的大量化学能白白损失,同时释放的CO2造成环境的污染。本论文以综合利用苹果修剪枝为出发点,研究了陕西省每年的苹果修剪总量,不同年龄修剪枝的燃烧热值和苹果修剪枝中主要成分木质素和半纤维素的提取及理化性质,结论如下:（1）通过对陕西苹果修剪量的抽样调查可知:苹果修剪枝的平均含水量为44.95%,其中,一年生修剪枝的含水量为47.89%,二年生修剪枝的为45.16%,三年及以上生修剪枝为41.40%。用平均生物量法计算出陕西省每年苹果修剪枝的总生物量（干物质）为392.65万t左右。（2）用氧弹式量热计对不同年龄的苹果修剪枝进行了燃烧热值的测定,结果表明,三个不同年龄段的修剪枝燃烧热值相差不大,分别为:一年生17284.821 J·g^-1,二年生17318.703 J·g^-1,三年及以生17411.245 J·g^-1,平均为17338.256J·g^-1。（3）用不同质量分数的NaOH从苹果修剪枝中提取木质素和半纤维素,并利用GC、HPLC、FT-IR和TGA-DTA仪器分析其化学和物理特征。三个年龄段的苹果修剪枝中苯醇提取物的含量均较低,其中一年生为2.69%,二年生为4.93%,三年及以上生为4.38%;无论木质素还是半纤维素,其产率都是在1%NaOH质量分数时最高,然后随着NaOH质量分数的增加,木质素和半纤维素的产率逐渐减少。在三个不同年龄的修剪枝中,二年生枝条半纤维素的总提取率最高,为25.72%,一年生枝条的总产率最低,为18.87%;而木质素的总产率恰恰相反,二年生枝条的最低,为4.34%,一年生枝条的最高,为6.10%,三年及以上生的居中。（4）从二年生修剪枝提取的半纤维素的糖组分来看,其半纤维素制备物的主要组成是聚葡萄糖木糖,即聚氧-乙酰基-4-O-甲基葡萄糖醛酸木糖。通过对二年生苹果修剪枝木质素制备物的碱性硝基苯氧化结果分析,在木质素的制备物中香草醛和丁香酸是主要产物,还有大量的香草酸和芳香酸,没食子酸、对香豆酸和阿魏酸含量很低,这说明二年生苹果修剪枝中木质素是G-S-H型木质素。（5）通过对木质素制备物分子量的测定,结果表明:其重均分子量和多分散性都无显著差异,分子量在1200～5000之间;多分散性均在1.236～1.692之间。而半纤维素制备物的重均分子量和多分散性差异均比较显著,相对分子质量从103720g·mol^-1随着碱液浓度的增加而减小,其值16693g·mol^-1,多分散系数在3.916～94.291之间,分子量分布范围宽窄不等。（6）通过对木质素和半纤维素制备物的FT-IR谱图分析可知,其分子内部含有较多活性基团,具有较高的化学活性,可为开发高应用价值的化学产品提供原料;从其TGA-DTA曲线可知,木质素和半纤维素的最大失重温度均在280℃附近。用X-射线衍射法对其提取后的残渣进行了结晶度的测定,发现其纤维的结晶度不足40%,故认为其纤维不适合作为造纸的原料。更多还原

【Abstract】 Under the dual pressures of energy shortage and environmental protection, the exploitation and utilization of biomass energy has been paid more extensive attentions during these years. Apple trees, as one of an economic species, Shaanxi’s Cultivation Area ranks first in China, A great amount of branches are pruned annual, but these branches and tree trunks are often being used in the low efficiency of direct combustion, or long-term decadent stack used as a kind of fertilizer, resulting in inadequate use of resources and a large number of potential chemical energy in branch lost in vain. Meantime, CO2 released by combustion destroy the environment. Viewed from comprehensive utilization of apple pruning branches in Shaanxi Province, this paper studied the annual total pruning apples in Shaanxi Province, determined the combustion heat value of different ages pruning branches, extracted lignin and hemicellulose of the main components of Apple pruning branches and analyzed their physico-chemical properties. The following main conclusions can be drawn:（1） By using sample survey method to investigate the amount of Apple pruning branches in Shaanxi province, we could see that: The average water content of Apple pruning branches was 44.95 percent, of which water content of one-year-old pruning branches was 47.89 percent, biennial pruning branches was 45.16 percent, and perennial pruning branches was 41.40 percent. The total apple pruning biomass （dry matter） was about 392.65million tons per year calculated by an average biomass method.（2） The calorific value of Apple pruning branches of different age groups have been determined by Oxygen bomb calorimeter. The results show that there was a small difference among the three different ages of pruning branches, the calorific value of branches were as follows: one-year-old was 17284.821J·g^-1, biennial was 17318.703J·g^-1, perennial was 17411.245J·g^-1. And the average calorific value was 17338.256J·g^-1.（3）This study extracted lignin and hemicellulose from apple pruning branches with different mass fraction of NaOH, and analyzed their chemical and physical characteristics using the GC, HPLC, FT-IR and TGA-DTA. Benzene-alcohol extraction of Apple pruning branches of the three age groups were relatively low, with one-year-old was minimum, 2.69 percent, biennial was highest, 4.93 percent, perennial was in the middle with 4.38 percent. No matter lignin and hemicellulose, their yields were highest when the mass fraction was 1 percent NaOH and with the mass fraction of NaOH increased, the yield of lignin and hemicellulose decreased. In three different ages, total hemicellulose extraction rate of biennial Apple pruning branches was highest, 25.72 percent, one-year-old branches was the lowest, 18.87 percent. And the total yield of lignin was on the contrary, biennial branches was lowest, 4.34 percent and one-year-old branches was highest, 6.10 percent, perennial was in the middle.（4）Viewed from the sugar components of hemicellulose of the biennial pruning, the major component of the hemi-cellulose material Preparation was polydextrose xylose, which was polyoxyethylene - acetyl - 4-O-methyl glucuronic acid xylose. Through analyzing results of alkaline nitrobenzene oxidation of lignin Preparation of biennial Apple pruning branches, vanillin and syringic acid were the main products in the lignin Preparation and there were a large number of homovanillic acid, aromatic acid, gallic acid. P-coumaric acid and ferulic acid content were very low, which indicated lignin in biennial Apple pruning branches was GSH-type lignin.（5） Molecular weight of lignin Preparation was measured, and its weight average molecular weight and polydispersity have no significant differences. Molecular weight was between 1200 and 5000. Polydispersity was between 1.236 and 1.692. and the weight average molecular weight and polydispersity of hemi-cellulose material Preparation had significant differences, relative molecular mass decreased from 103720g·mol^-1 to 16693g·mol^-1 with the increase of alkali concentration. Polydispersity coefficient was between 3.916 and 94.291 and the range of molecular weight distribution is unequal.（6）By analyzing FT-IR spectra of lignin and hemicellulose preparation, we could see that its internal elements contained more active groups with high chemical activity and could be applied for the development of high value chemical products materials. The TGA-DTA curves showed that the biggest weight-loss temperature of lignin and hemicellulose were around 280℃. Determination of the crystallinity of residue after extraction Using X-ray diffraction found that crystallinity of fibers was less than 40%, so that its fibers were not suitable for papermaking as a raw material.更多还原