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1.
理化预处理麦秸改善其聚丙烯复合材料抗霉菌腐蚀力学性能 总被引：3，自引：2，他引：1
为探讨麦秸秆不同处理方法对其制备的聚丙烯（polypropylene,PP）复合材料耐霉菌腐蚀性能影响,采用NaOH、HAc、水热、微波4种方法对麦秸秆纤维进行表面预处理,并对未处理和4种处理麦秸秆制备的复合材料进行霉菌加速腐蚀试验,测试了5种复合材料腐蚀前后的力学性能、颜色变化和吸水性,用傅立叶红外光谱分析其官能团的变化,观察并分析复合材料表面霉菌生长情况及表面微观结构。结果表明：霉菌能腐蚀麦秸秆纤维中的纤维素、半纤维素和木质素,使复合材料表面产生裂纹和孔洞,预处理可改善麦秸秆纤维和PP基体间的界面结合,有效地阻止霉菌腐蚀复合材料中麦秸秆的纤维素、半纤维素和木质素,其中5%NaOH预处理效果最佳,其弯曲强度、拉伸和冲击强度分别比未处理的提高了1.68%、3.67%和75.28%,吸水率和色差值降低12.99%和55.25%,经预处理麦秸秆制备复合材料腐蚀后表面裂纹和较大孔洞减少。该研究结果可为提高木塑复合材料防霉效力提供试验数据和理论参考,有利于延长木塑复合材料使用寿命。 相似文献
2.
A sequential totally chlorine-free procedure for isolation of cellulose from wheat straw was proposed in this study. The dewaxed straw was pretreated with 0.5 M NaOH in 60% methanol at 60 degrees C for 2.5 h under ultrasonic irradiation for 0-35 min and sequentially posttreated with 2% H(2)O(2)-0.2% TAED at pH 11.8 for 12 h at 48 degrees C, which together solubilized 85.3-86.1% of the original hemicelluloses and 91.7-93.2% of the original lignin, respectively. The yield of crude cellulose ranged between 46.2 and 49.2% on a dry weight basis related to wheat straw, which contained 11.2-12.2% residual hemicelluloses and 2.5-2.9% remaining lignin. Further treatment of the corresponding crude cellulosic preparations with 80% acetic acid-70% nitric acid under the condition given yielded 36.8-37.7% of the purified cellulose, which contained minor amounts of bound hemicelluloses (2.5-2.8%) and was relatively free of associated lignin (0.1-0.2%). The isolated crude and purified cellulose samples were comparatively studied by FT-IR and CP/MAS (13)C NMR spectroscopy, and the relative crystallinity was also estimated. The final stage treatment with 80% acetic acid-70% nitric acid decreased the hemicelluloses and lignin associated in the crude cellulose but led to 3.1-5.4% degradation of the original cellulose; in addition, the purity of the obtained cellulose was high. However, it was found that the final stage treatment is not severe enough to cause decrystallization of cellulose. The thermal stability of the purified cellulose is higher than that of the corresponding crude cellulose. 相似文献
3.
Oliveira L Evtuguin DV Cordeiro N Silvestre AJ Silva AM Torres IC 《Journal of agricultural and food chemistry》2006,54(7):2598-2605
Dioxane lignin (DL) isolated from leaf sheaths of banana plant (Musa acuminata Colla var. cavendish) and in situ lignin were submitted to a comprehensive structural characterization employing spectroscopic (UV, FTIR, solid state 13C CP-MAS NMR, liquid state 13C and 1H NMR) and chemical degradation techniques (permanganate and nitrobenzene oxidation). Results obtained showed that banana plant leaf sheath lignin is of HGS type with a molar proportion of p-hydroxyphenyl (H)/guaiacyl (G)/syringyl (S) units of 12:25:63. Most of the H units in DL are terminal phenolic coumarates linked to other lignin substructures by benzyl and Cgamma-ester bonds in contrast to ferulates that are mainly ether linked to bulk lignin. It is proposed that banana plant leaf sheath lignin is chemically bonded to suberin-like components of cell tissues by ester linkages via essentially hydroxycinnamic acid residues. beta-O-4 structures (0.31/C6), the most abundant in DL, comprise mainly S units, whereas a significant proportion of G units is bonded by beta-5, 5-5', and 4-O-5' linkages contributing to ca. 80% of condensed structures in DL. 相似文献
4.
不同施氮量下潮土中小麦秸秆腐解特性及其养分释放和结构变化特征 总被引：3，自引：0，他引：3
5.
汽爆麦草的两相法生物气化 总被引：7，自引：0，他引：7
蒸汽爆破作为一种新型的预处理方法被初次运用于麦草的两相气化系统,以碳酸氢铵作为补充氮源调节碳氮比,并在相同条件下以未汽爆麦草作对照试验。以汽爆麦草为原料时,水解反应器的pH值低于加入未汽爆麦草的pH值,并且在25 d后慢慢升至7;以两种麦草为原料时,甲烷反应器的pH都稳定在7左右,此时最适合甲烷生成。汽爆麦草的总固形物和挥发性固形物含量分别降低了57.5% 和62.1%,下降率差不多是未汽爆麦草的2倍;纤维素和半纤维素的降解率也有了显著的提高,分别为63.0% 和67.4%;木质素的降解率变化不大,都在5％左右。汽爆麦草的总产气量高于非汽爆麦草,并且一直保持较高的增长率,而非汽爆麦草的增长率一直较低;两种麦草产生的生物气中的甲烷含量大致相同,在水解反应器中后期为50％左右,在甲烷反应器中为70％左右。以上结果表明,汽爆可以促进麦草的降解,提高生物气的产量,是一种行之有效的预处理技术。 相似文献
6.
为降低有机酸催化剂对设备的腐蚀,提高秸秆类生物质原料的利用率,该文以合成的1-甲基-3-(4-磺酸基丁基)咪唑硫酸氢盐离子液体为催化剂,乙醇为溶剂,考察小麦秸秆的液化过程,并对离子液体的结构进行傅里叶红外光谱和核磁共振表征,对液化后的残渣和液相产物进行傅里叶红外光谱、热重和气质联用分析。试验和表征结果表明:合成的1-甲基-3-(4-磺酸基丁基)咪唑硫酸氢盐离子液体对秸秆液化具有较优的催化性能,在反应温度为200℃、反应时间为60 min、离子液体用量为26%的条件下,液化率可达85.5%,同时乙酰丙酸乙酯的得率为9.97%,在液化产物中的相对百分含量为29.9%;液化产物中包含有醛、酮、酯、酸和酚类等含氧化合物,其中酚类化合物主要源于木质素的降解,其他化合物则主要源于半纤维素和纤维素的降解。研究结果为开发利用低腐蚀性环保型催化剂催化液化秸秆制备高品位化学品提供理论依据。 相似文献
7.
C. AMALFITANO V. PIGNALOSA L. AURIEMMA A. RAMUNNI 《European Journal of Soil Science》1992,43(3):495-504
An Andisol from the Vesuvian volcanic area, low in organic matter, was treated with wheat straw (20/1 w/w) and urea (500/1 w/w) in pots, and maintained at 60–90% of field capacity in an open greenhouse in order to study the yields and properties of humic acids after 30, 122 and 224 d, and 1, 2 and 3 years of incubation. During the first year the yields increased, but subsequently they showed a decrease. However, the chemical and spectroscopic properties of humic acids remained substantially constant. The chemical characteristics of modified lignin from added wheat straw were recognized in the properties of humic acids by UV-visible, FT-IR and 13C CP-MAS NMR spectroscopic analysis. Evidence was obtained that these modifications included the microbial removal of carbohydrates, the oxidative destruction or transformation of the side chains of lignin units, the demethylation of mainly guaiacyl, and subsequent oxidation of catechol-like structures to o-quinone. The latter can be postulated to promote the nucleophilic addition of amino compounds with formation of aromatic amines in humic acids. 相似文献
8.
针对目前中国小麦秸秆利用率不高以及燃烧秸秆所带来的环境污染问题,该文研究了利用稀烧碱溶液处理小秸秆以制备用于复合材料的小麦秸秆纤维的性能及制备工艺,研究了氢氧化钠溶液质量分数、液固比、处理温度和处时间等工艺参数与小麦秸秆纤维失重率的关系,并对所制备的小麦秸秆纤维的强伸性能、表面性能进行了测试。结果明,小麦秸秆经稀烧碱溶液处理(氢氧化钠质量分数4%、液固比30mL/g、处理温度100℃、处理时间60min)后制的小麦秸秆纤维力学性能与原样相比没有明显损伤,但内、外表面结构均变得疏松,比表面积增大,滴水接触角变小从而提高了聚合物聚乳酸对秸秆纤维的浸润性能,提高了二者之间界面的粘结性。该研究结果为利用小麦秸秆制备秸纤维增强聚乳酸复合材料提供参考。 相似文献
9.
探究不同植物残体还田条件下微生物关键种如何影响木质素酚的浓度(木质素酚与土壤有机碳的比值),旨在为不同有机物料还田培肥土壤提供理论和技术依据。本研究以河西绿洲灌区的灌漠土作为研究对象,开展了30 a以施加绿肥(GM)、小麦秸秆(SW)、氮肥(N)、绿肥配施氮肥(GMN)、小麦秸秆配施氮肥(SWN)以及不施肥(CK) 6种不同施肥处理的培肥试验。结果表明:GM和SW处理的土壤有机碳含量显著高于其他处理;有小麦秸秆参与还田的处理显著提高了总木质素酚浓度以及3种木质素酚类单体的浓度,其中总木质素酚浓度在SW处理中分别比CK、GM、N、GMN和SWN处理高了109%、122%、115%、164%和57%;对比不施肥和施化肥处理,植物残体还田显著提高了微生物关键种F3(盘菌纲,Pezizomycetes)、F26(被孢霉菌纲,Mortierellomycetes)、F173(粪壳菌纲,Sordariomycetes)、B74(阿尔法变形菌纲,Alphaproteobacteria)和B87(放线菌纲,Actinobacteria)的相对丰度。本研究共鉴定出15个关键种,其中关键种B831(属阿尔... 相似文献
10.
为了利用小麦秸秆通过均相反应制备羧甲基纤维素(CMC,carboxymethyl cellulose),采用氢氧化钠和过氧化氢回流加热法制备小麦秸秆纤维素。以加入氧化锌的氢氧化钠/尿素/硫脲体系为溶剂,采用冻融循环法溶解小麦秸秆纤维素,利用正交试验获得了该溶解体系的最佳组成。在溶解了小麦秸秆纤维素的氢氧化钠/尿素/硫脲/氧化锌的体系中,以氯乙酸钠为醚化剂制备CMC,并对其进行红外光谱分析和取代度(degree of substitution,DS)测定。结果表明:在固液比为1∶20 g/mL,质量分数为10%NaOH,反应温度为85℃,回流3.5 h和固液比为1∶30 g/m L,质量分数为3%H_2O_2,反应温度为85℃,回流3 h处理小麦秸秆,纤维素提取率最高为84.61%,同时能较好的脱除半纤维素和木质素;最佳溶解体系为:质量分数为7%NaOH,11%硫脲,5%尿素,0.05%氧化锌,0℃时,最大溶解度为2.880 1 g。红外光谱试验表明小麦秸秆纤维素与微晶纤维素特征吸收峰基本一致,醚化反应生成的CMC与商品CMC的特征吸收峰基本一致。CMC的取代度受纤维素用量、温度和氯乙酸钠与纤维素葡萄糖单元(AGU,anhydroglucose unit)的摩尔比影响,随纤维素用量和氯乙酸钠与纤维素AGU的摩尔比增大而提高,随醚化温度的增加先增大(55℃)后降低。研究结果为以小麦秸秆为原料,经NaOH和H_2O_2处理获得纤维素,溶解在加入氧化锌的氢氧化钠/尿素/硫脲体系中,与氯乙酸钠经过均相醚化反应合成取代度较高的CMC提供参考。 相似文献
11.
乙二醇-氯化铁预处理对棉秆酶水解效率的影响 总被引：1，自引：1，他引：0
为提高棉秆的纤维素酶水解效率,该研究以乙二醇为预处理溶剂,氯化铁为催化剂对棉秆进行预处理,实现了棉秆木质素和半纤维素的有效去除,提高了酶水解效率。以木质素和半纤维素的去除率为指标,运用正交试验方法优化乙二醇-氯化铁预处理条件。结果表明,棉秆在90%乙二醇水溶液,0.1 mol/L氯化铁,固液比1∶15,160 ℃条件下处理20 min,木质素和半纤维素去除率分别为85.7%和88.9%。相较原料,预处理后棉秆酶解率提高了7.6倍,葡萄糖产率达到100%（基质浓度5%,酶载量8.3 FPU/g,水解72 h条件下）。通过结构表征发现乙二醇-氯化铁预处理使棉秆的比表面积增大,致密结构被破坏,有效提高了棉秆的纤维素酶可及性。 相似文献
12.
小麦秸秆木质素含量高,蛋白质等营养物质含量低,作为反刍家畜的粗饲料营养价值低,饲料化利用受到限制。通过室内小麦秸秆固态发酵试验,研究了两株侧耳属真菌Tf1（Pleurotussajor—c4u）和JG1（PleurotusCornucopiaeRoll）对小麦秸秆细胞壁化学组分的降解、瘤胃消化率和粗蛋白含量的影响。结果表明,经菌株JG1、Tf1和两菌复合发酵21d的小麦秸秆,木质素降解率分别为28．20％、30．78％和38．41％,纤维素降解率分别为19．26％、19．28％和26．65％;48h干物质瘤胃消化率分别比未发酵秸秆提高了38．62％、44．81％和55．89％,中性洗涤纤维（NDF）消化率分别提高了38．91％、49．00％和63．08％;粗蛋白含量分别比未发酵秸秆提高了58．60％、69．53％和72．22％。表明菌株JG1和Tf1在选择性降解木质素,改善瘤胃消化率,提高粗蛋白含量方面的优势,而且两菌株复合发酵具有协同作用,与单菌发酵相比,木质素降解率、瘤胃消化率和粗蛋白含量都明显提高。 相似文献
13.
CO2浓度升高对小麦秸秆性质、数量及其分解的影响 总被引：2，自引：0，他引：2
在江都FACE平台上观测了常N水平下大气CO2浓度升高对小麦秸秆数量和性质的影响,并利用稻季淹水培养试验研究了CO2浓度升高引起的小麦秸秆量和质的改变对其腐解和土壤微生物量碳的影响,结果表明:CO2浓度升高显著降低了麦秸中N含量,导致麦秸C/N和木质素/N比显著增加,但对麦秸其他生化组成——可溶物、半纤维素、纤维素、木质素和酚含量均无影响;CO2浓度升高引起的小麦秸秆性质改变对麦秸及其含C物质的分解均无显著影响,但显著减缓了含N物质的分解;若将收获的麦秸全部还田,CO2浓度升高引起的小麦秸秆量的增加也没有显著影响麦秸及其含C、N物质的分解。由于高CO2浓度导致的麦秸性质改变对土壤微生物量碳无显著影响,这也是CO2浓度升高引起麦秸性质变化幅度太小不足以影响麦秸及其含C物质分解的主要原因。 相似文献
14.
为揭示不同还田方式下北方旱作小麦秸秆腐解规律,以小麦秸秆为试验材料,采用尼龙网袋法,于2014-2015年度在山西临汾保护性耕作长期定位试验区进行试验,设置秸秆还田旋耕(SRT)、秸秆覆盖免耕(SNT)2个处理,分析不同耕作方式下小麦秸秆的纤维素、半纤维素、木质素、有机碳、全氮含量以及秸秆腐解率、有机碳矿化率、全氮释放率的变化。结果显示,经过375 d的田间腐解,SRT秸秆腐解率为50%,SNT秸秆腐解率为31%。SRT秸秆的纤维素、半纤维素、木质素的平均腐解率分别为65%、45%、53%,SNT分别为56%、30%、39%;SRT秸秆有机碳的矿化率为57%,SNT为40%;SRT秸秆全氮素释放率为15%,SNT为36%。研究表明,SRT可加快秸秆腐解与组成成分的分解,SNT有利于秸秆氮素的释放,可减少农田氮投入。SNT秸秆有机碳矿化率低可减少农田碳循环速率,提高麦田固碳能力。本研究结果对我国北方旱作小麦秸秆还田管理具有一定的借鉴参考价值。 相似文献
15.
淹水条件下FACE处理的水稻以及小麦秸秆的分解及产物 总被引：2，自引：0，他引：2
Winter wheat and rice straw produced under ambient and elevated CO2 in a China rice-wheat rotation free-air CO2 enrichment (FACE) experiment was mixed with a paddy soil at a rate of 10 g kg-1 (air-dried), and the mixture was incubated under flooded conditions at 25 ℃ to examine the differences in decomposition as well as the products of crop residues produced under elevated CO2. Results showed that the C/N ratio and the amount of soluble fraction in the amended rice straw grown under elevated CO2 (FR) were 9.8% and 73.1% greater, and the cellulose and lignin were 16.0% and 9.9% lesser than those of the amended rice straw grown under ambient CO2 (AR), respectively. Compared with those of the AR treatment, the CO2-C and CH4-C emissions in the FR treatment for 25 d were increased by 7.9% and 25.0%, respectively; a higher ratio of CH4 to CO2 emissions induced by straw in the FR treatment was also observed. In contrast, in the treatments with winter wheat straw, the CO2-C and CH4-C productions, the ratio of straw-induced CH4 to CO2 emissions, and the straw composition were not significantly affected by elevated CO2, except for an 8.0% decrease in total N and a 9.7% increase in C/N ratio in the wheat straw grown under elevated CO2. Correlation analysis showed that the net CO2-C and CH4-C emissions from straw and the ratio of straw-induced CH4 to CO2 emissions were all exponentially related to the amount of soluble fraction in the amended straw (P < 0.05). These indicated that under flooded conditions, the turnover and CH4 emission from crop straw incorporated into soil were dependent on the effect of elevated CO2 on straw composition, and varied with crop species. Incorporation of rice straw grown under elevated CO2 would stimulate CH4 emission from flooded rice fields, whereas winter wheat straw grown under elevated CO2 had no effect on CH4 emission. 相似文献
16.
A combination of solid‐state CPMAS‐13C‐NMR and TMAH thermochemolysis‐GC/MS was applied to investigate the molecular composition of particulate organic matter (POM) separated from a Chinese paddy soil, from the Tai Lake region, under a long‐term field experiment with different fertilizer treatments. The treatments were: (i) no fertilizer application (NF), (ii) chemical fertilizers only (CF), (iii) chemical fertilizer plus pig manure (CFM) and (iv) chemical fertilizer plus crop straw (CFS). CPMAS‐13C‐NMR spectra showed that POM from all treated plots was rich in O‐alkyl‐C compounds, followed by alkyl‐C and aromatic‐C compounds. However, as compared with a control (NF), POM under CFM and CFS treatments exhibited a smaller relative O‐alkyl‐C content and a larger contribution of aromatic‐C and alkyl‐C, thus increasing both aromaticity and hydrophobicity and, hence, recalcitrance of POM samples. Thermochemolysis of POM from all treatments demonstrated a dominance of aliphatic and lignin‐derived compounds. However, the distribution of lignin monomers (p‐hydroxyphenyl, P, guaiacyl, G, and syringyl, S) revealed significant differences among the treatments. The relative distribution of lignin P, G and S monomers in NF, CF and CFS indicated a preferential contribution of annual crops and maize straw, as compared with that found for CFM. Concomitantly, a larger content of aliphatic thermochemolysis derivatives was found for CFS and CFM. The relative increase of aliphatic molecules in CFS was attributed to hydrophobic polyesters from higher plants. In the CF and CFM systems, the presence of aliphatic components of microbial origin suggested a greater microbial activity in comparison with NF and CFS. The combined application of solid state CPMAS‐13C‐NMR and TMAH thermochemolysis‐GC/MS can be used to assess effectively the accumulation of recalcitrant organic compounds in soil POM under long‐term fertilizer application with organic biomass. It is thus inferred that soil organic matter stabilization by molecular recalcitrance contributes to carbon sequestration in Chinese paddy soils under long‐term managements. 相似文献
17.
Extraction and characterization of original lignin and hemicelluloses from wheat straw 总被引：2，自引：0，他引：2
Original lignin and hemicelluloses were sequentially extracted with high yield/purity, using acidic dioxane/water solution and dimethyl sulfoxide, from ball-milled wheat straw. The acidic dioxane lignin fraction is distinguished by high beta-O-4' structures and by low amounts of condensed units (beta-5', 5-5', and beta-1'). Hemicelluloses contain arabinoxylans as the major polysaccharides, which are substituted by alpha-l-arabinofuranose, 4-O-methylglucuronic acid, acetyl group (DS = 0.1), and xylose at O-3 and/or O-2 of xylans. It was found that arabinoxylans form cross-links with lignins through ferulates via ether bonds, glucuronic acid via ester bonds, and arbinose/xylose via both ether and glycosidic bonds, respectively, in the cell walls of wheat straw. Diferulates are also incorporated into cross-links between lignin and hemicelluloses as well as lignification of wheat straw cell walls. The guaiacyl unit is considered to be a significant condensed structural constructor in extracted lignin and a connector between lignin and carbohydrates. 相似文献
18.
A sequential treatment of dewaxed barley straw with sodium hydroxide, different concentrations of hydrogen peroxide, and potassium hydroxide/sodium borate degraded various proportions of the original lignin and solubilized different amounts of the original hemicelluloses. The isolated lignin fractions were subjected to comprehensive structural characterization by UV, FT-IR, and (13)C NMR spectroscopy, and their chemical compositions were analyzed by alkaline nitrobenzene oxidation. All of the lignin fractions were typical of grass lignins and had weight-average molecular weights between 1750 and 2190. It was found that the peroxide treatment at low concentrations (< or =2.0%) resulted in a slight increase in the amount of carboxyl groups, whereas the treatment at a relatively high concentration of alkaline peroxide, such as at 3.0% H(2)O(2), led to a noticeable oxidation of the lignins, as shown by an increase of carboxyl groups. Moreover, the results obtained indicated that the successive treatments with alkali and alkaline peroxide under the conditions used did not significantly affect the beta-O-4 structures of lignins. Substantial amounts of etherified ferulic acids were cleaved by the sequential treatments with alkaline peroxide, as shown in the (13)C NMR spectra. The results underscore the structural differences between alkali- and alkaline peroxide-soluble lignins from barley straw. 相似文献
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20.
小麦玉米秸秆连续还田对土壤有机质红外光谱特征及氮素形态的影响 总被引：2，自引：0，他引：2
通过6年的田间定位试验,探讨了CK(不施肥,秸秆不还田)、SF(施肥,秸秆不还田)、T1(施肥,玉米秸秆还田)、T2(施肥,小麦秸秆还田)、T3(施肥,玉米小麦秸秆还田)5种处理对土壤氮素形态和有机质红外光谱特征的影响。结果显示:与SF相比较,T1、T2、T3处理使土壤有机氮含量分别增加3.7%、15.9%和18.5%,土壤无机氮含量分别减少15.5%、15.9%和24.0%,其中铵态氮分别降低11.3%、6.0%和12.0%,土壤硝态氮含量分别降低19.3%、22.9%和32.1%;与SF相比较,T1、T3处理土壤有机质(SOM)的C/N分别降低2.8%和1.4%,T2处理SOM的C/N提高1.4%;C/O分别提高9.2%、12.8%和12.1%;而H/C分别降低4.6%、5.5%和4.6%。红外图谱分析显示,T1、T2、T3处理引起3 500~3 200 cm?1处的吸收峰增加,2 924 cm?1处出现了新的弱峰,表明SOM的脂肪族特征增加,且以1 630 cm?1处为中心的宽带吸收峰强度明显增加,SOM芳构化程度增强。研究表明,施肥显著提高了土壤有机氮、无机氮含量,以及土壤有机质的C/N和C/O。而秸秆还田降低了土壤无机氮,提高了土壤有机氮,使SOM的C/N、H/C下降,C/O上升,同时提高了SOM中酚基、羟基、羧基、芳香碳和酰胺含量,其中以小麦、玉米秸秆双季还田的效果最为显著。 相似文献