全梗全叶再造烟叶热裂解产物与感官质量关系研究

通过对全梗、全叶单体原料制备的再造烟叶热裂解产物GC-MS鉴定分析,探讨热解产物的差异性对感官质量的影响。结果表明,梗、叶单体原料制备的再造烟叶热裂解产物主要包括醛、酮、酚、芳烃、杂环类物质,其中全梗再造烟叶检出49种物质,全叶再造烟叶检出60种物质。全叶再造烟叶热裂解产物中的主要烟草中重要的致香物质醛、酮、酚类物质的数量和所占比例明显高于梗再造烟叶;芳烃和杂环类物质的数量和所占比例较接近;全叶再造烟叶在香气质、杂气、刺激性方面明显优于全梗再造烟叶,这与全叶再造烟叶热裂解产物中的烟草主要致香成分释放量明显高于全梗再造烟叶有直接关系。     

多聚磷酸铵对再造烟叶热解行为与CO释放量的影响

应用热重分析研究多聚磷酸铵(APP)对再造烟叶热解行为的影响．热分析结果表明,APP降低再造烟叶热降解速率及其热释放量、促进了碳的形成,对再造烟叶的热降解起一定的阻碍作用．此外APP显著影响再造烟叶的热解过程中的气相产物,再造烟叶的CO单支释放量与单口释放量随着APP含量的增加快速下降．慢速热解与闪解实验结果显示升温速率是APP降低CO释放的关键因素．     

不同烟碎片制备的造纸法再造烟叶致香成分分析比较

为了研究不同烟碎片制备的再造烟叶在致香成分方面的差异,将白肋烟碎片、土耳其香料烟碎片、津巴布韦烤烟碎片和云南烤烟碎片这4种原料分别制备成不同再造烟叶,采用同时蒸馏萃取结合GC/MS方法对再造烟叶进行致香成分的分离,定量,检测和分析了酮类、醛类、醇类、酯类、酸类这5种不同类型致香成分的差异,结果显示:津巴布韦烤烟碎片和土耳其香料烟碎片制备的再造烟叶5类致香成分总量和酯类物质含量较高;津巴布韦烤烟碎片和白肋烟碎片制备的再造烟叶在酮类物质和醛类物质的含量上较高;白肋烟碎片制备的再造烟叶在酸类物质和醇类物质的含量上较低.     

基于热重红外联用分析的生物质热裂解机理研究

利用热重红外联用技术在线分析研究了白松在不同升温速率下的热裂解行为,结果表明木材的热裂解可归结于纤维素、半纤维素和木质素三种主要组分的热裂解。白松的热裂解产物主要有酸类、醇类、醛类、酮类、酯类、水分和小分子气体等。在线红外分析结果表明白松热裂解过程中先析出游离水,随后发生解聚和脱水反应,主要的苷键和碳碳键断开形成各种烃类、醇类、醛类和酸类等物质,随后,这些大分子物质又二次降解为一氧化碳为主的气体产物。     

不同裂解温度下生物炭释放溶解性有机质的光谱特征分析

生物炭释放的溶解性有机质(DOM)具有复杂的生物地球化学特征,影响着污染物的迁移与转化和全球碳循环等诸多环境过程。相比对生物炭理化性质、结构特征的研究,生物炭DOM的研究仍相对匮乏,其中裂解温度驱动下生物炭释放DOM的光谱特征鲜有报道。以两种常见且具有较好应用前景的生物炭—竹炭(楠竹生物炭)和木炭(柏木生物炭)为研究对象,通过紫外-可见光谱、三维荧光光谱结合平行因子法(3DEEMs-PARAFAC),研究不同裂解温度下(100～700℃)两种生物炭释放DOM的光谱特征。结果表明,裂解温度决定两种生物炭释放DOM的潜能及其光谱特征。裂解温度越高, DOM释放量越小,且400℃是所研究两种生物炭DOM释放的临界裂解温度,当裂解温度低于400℃,生物炭DOM释放明显,当裂解温度高于400℃,生物炭释放量很低且趋于稳定。柏木生物炭的DOM释放量明显高于楠竹生物炭。低温裂解过程中(300℃)两种生物炭DOM存在大量紫外-可见发色团,并随着裂解温度上升逐步分解。通过3DEEMs-PARAFAC从生物炭荧光溶解性有机物(FDOM)中分离出2个类腐殖质荧光物质(C1和C2)及1个类蛋白荧光物质(C3), 3个荧光组分对裂解温度的响应不同,类腐殖质荧光强度在300℃出现峰值,而后随裂解温度上升而下降,类蛋白物质始终随着裂解温度的上升而下降。低温裂解(200℃)以类蛋白荧光为主,随着温度上升,类腐殖质组分占主导。此外,基于光谱特征分析,裂解温度还影响两种生物炭DOM诸多生物地球化学特征,随着裂解温度上升,两种生物炭DOM的相对分子质量,芳香性、疏水性和腐殖化程度均先增大再减小,但对应的峰值温度各不一致。因生物质原料差异,楠竹生物炭DOM的相对分子质量,芳香性、疏水性和腐殖化程度均明显大于柏木生物炭。该研究结论将进一步为生物炭DOM的环境行为研究,生物炭应用过程中环境管理与评估提供有益的参考。     

烟叶中游离态氨基酸与卷烟主流烟气中氢氰酸的相关关系

分别用氨基酸分析仪法和离子色谱-脉冲安培检测法测定了60种单料烤烟烟叶中游离态氨基酸的含量和烟叶主流烟气中氢氰酸的释放量,通过相关性分析确定了对氢氰酸释放量具有主要影响的氨基酸,建立了氢氰酸释放量的预测模型.结果表明:所有碱性氨基酸和杂环氨基酸都与氢氰酸呈显著正相关,所有酸性氨基酸与氢氰酸都没有呈现显著相关性.根据相关性系数判断对烟草主流烟气中氢氰酸释放量起主要作用的氨基酸依次是:苯丙氨酸、色氨酸、组氨酸、丙氨酸、脯氨酸和丝氨酸.研究结果为吸烟与健康研究提供科学依据.     

声光可调近红外光谱技术快速检测再造烟叶的厚度

厚度是衡量再造烟叶品质及稳定性的一项重要指标,目前再造烟叶厚度测定方法存在读数不稳定、测量准确性受样品特性影响,不利于检测和控制.本文应用声光可调滤光器近红外光谱仪建立再造烟叶厚度检测方法模型,能准确预测再造烟叶厚度指标,具有准确性好,精密度高的特点,符合再造烟叶厚度检测的需要.     

生物质焦燃烬过程中NO释放行为的研究

研究了Beechwood焦燃尽过程中的NO释放行为,讨论了热解温度、热解气氛、二次热解对焦燃尽过程中NO释放的影响.结果显示Beechwood焦中氮含量的增加主要是由于焦对N2的吸附引起的,热解温度对Beechwood焦吸附N2的能力有较大影响.纤维素、半纤维素和木质素的试验显示纤维素具有一定的吸附N2的能力,而半纤维素对N2的吸附能力较差,几乎不吸收N2,木质素对N2的吸附能力不能确定.     

涂布率对再造烟叶综合品质的影响

为了对再造烟叶产品的设计开发与生产控制提供指导,研究涂布率对再造烟叶品质的影响,通过对不同涂布率的样品进行理化指标、感官质量评价,确定再造烟叶涂布率的适宜范围和最佳范围。结果表明,再造烟叶涂布率的适宜范围在45%—75%之间,最佳范围在55%—65%之间。     

近红外光谱烟叶质量等级快速检测与等级特征分析

烤烟等级质量对配方设计和卷烟工业生产的稳定起着重要的作用。采用传统外观分级法对2018年全国40个地级市产地的768份烤烟烟叶样品进行分类定级,包括7个不同烟叶质量等级。应用近红外光谱建立烟叶质量等级预测模型,分析不同等级烟叶化学基团及相关成分的近红外吸收光谱特征。结果表明：不分产区建立全国烟叶等级预测模型,建模集与预测集的预测标准差不大于1.35。将样品按五大产区分区后,建立各产区模型,发现较全国模型,分区后各个产区所建模型的预测标准差有所降低,其中东南、西南、黄淮烟区模型提高较大,检验集与预测标准差均不大于1.07。对不同质量等级烟叶的平均光谱进行标准正态变量变换预处理后,依据近红外光在不同频率范围吸收的有机基团及相关物质成分信息,发现质量等级较好的烟叶,纤维素含量较低,淀粉等糖类物质含量较高;质量等级较差的烟叶,纤维素含量较高,淀粉等糖类物质含量较低;质量等级最差（上部低等）烟叶,同时具有蛋白质类物质含量较高的特点。因此,应用近红外光谱可实现烟叶质量等级的快速预测,预测偏差基本在相邻等级之间,满足实际应用要求,通过建立不同产区预测模型可进一步提高预测准确度;同时,不同等级烟叶在以纤维素、淀粉和糖类、蛋白质类等物质为主产生的基团吸收特征不同,这也是应用近红外光谱实现烟叶质量等级快速检测的信息基础。该研究结果对完善烟叶分级评价体系,进一步优化分级方案,为产品质量和维护等方面可提供了更加科学的方法指导和技术支撑。     

Catalytic mechanisms of potassium salts on pyrolysis of β-O-4 type lignin model polymer based on DFT study

In this study, the possible catalytic mechanisms of potassium salts on lignin pyrolysis was investigated with two β-O-4 type lignin model dimers with different oxygen functional groups on C_α using density functional theory (DFT) calculations. It was found that potassium salts (such as KOH and K₂CO₃) can react with phenol hydroxyl in lignin to form organic-K and further catalyze pyrolysis progress. Through this catalytic mechanism, potassium salts promoted the removal of C_α on specific intermediates and the demethylation of methoxy groups during β-O-4 type lignin pyrolysis, promoted the decomposition of intermediates, and facilitated the formation of phenol and CO₂.     

水热法碱活化生物质乙醇木质素的化学结构变化

为了提高生物质乙醇木质素的反应活性,采用水热法在四种不同碱性条件下对生物质乙醇木质素进行催化活化处理。运用傅里叶变换红外光谱(FTIR)、核磁共振氢谱(1H-NMR)、凝胶色谱(GPC)和有机元素分析手段研究了生物质乙醇木质素被四种碱(NaOH, KOH, K₂CO₃和Na₂CO₃)催化活化前后木质素的化学结构以及组分变化。FTIR结果表明生物质乙醇木质素碱经处理后,木质素的酚羟基特征吸收峰1 375 cm-1都有明显增大趋势,醚键振动吸收峰1 116 cm-1减弱,1 597和1 511 cm-1处苯环骨架振动吸收峰强度变化很小;1H-NMR分析结果表明酚羟基含量都有增大趋势,增加顺序为：KOH>NaOH>K₂CO₃>Na₂CO₃,其中KOH处理后的木质素酚羟基含量增加量为原木素的170%。这由于离子半径大的钾离子更容易与木质素β—O—4醚键上的氧形成加和物,进而发生醚键断裂反应,生成新的酚结构衍生物。GPC 表明生物质乙醇木质素碱处理后分子量分布向低分子区域扩展, 数均和重均分子量减小。元素分析结果显示木质素经过水热反应处理后,C含量都有所增加,而H和O含量则降低了,表明木质素经水热反应处理过程中有脱羧基作用,同时蛋白质的含量也有所降低,提高了木质素的纯度。这都有利于直接将木质素用于制备酚醛树脂胶黏剂。     

葡萄糖与脯氨酸的梅拉德反应物致香成分分析及其在造纸法再造烟叶中的应用

制备了等摩尔的D-葡萄糖和L-脯氨酸在温度95-100℃条件下反应4h的梅拉德反应产物.采用同时蒸馏萃取法对反应产物中的致香成分进行GS/MS分析,并用该产物进行了造纸法再造烟叶加香实验,且将加香后的造纸法再造烟叶样品添加在卷烟配方中进行了评吸.在D-葡萄糖和L-脯氨酸的梅拉德反应产物中一共鉴定出了19个化学物,主要包...     

Ultrasound-alkaline combined extraction improves the release of bound polyphenols from pitahaya (Hylocereus undatus 'Foo-Lon') peel: Composition,antioxidant activities and enzyme inhibitory activity

In this study, ultrasound-assisted alkaline hydrolysis was used to extract polyphenols from pitahaya peel. The effects of sonication time, ultrasonic density, NaOH concentration and the liquid–material ratio on the total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity of the extracts were studied. The composition and content difference of the extracts were analyzed and the inhibitory effect of α-amylase and α-glucosidase was measured. The results of single-factor analysis showed that when the sonication time was 45 min, the ultrasonic density was 32 W/L, the NaOH solution concentration was 6 M and the liquid–material ratio was 30 mL/g, the release of phenolic compounds was the largest and the antioxidant activity was the strongest. An UPLC-QTOF-MS/MS method was used to analyze the components and contents of the extracts. We found that there was a great difference in the component content of the free polyphenol extract and the bound polyphenol extract. From the results, we concluded that there was a strong correlation between the type and content of phenolic compounds and antioxidant activities, indicating that phenolic compounds were the main compounds of these biological activities. Moreover, the bound polyphenol extracts showed a significant inhibitory effect on α-amylase and α-glucosidase was stronger than that of the free polyphenol extracts. In addition, scanning electron microscopy showed that ultrasound-assisted extraction is crucial to the destruction of the cell wall and the release of bound polyphenols. Therefore, the pitahaya peel has the potential for therapeutic, nutritional, and functional food applications, and ultrasound-assisted alkaline hydrolysis is an effective means to release phenolic compounds.     

Primary release and transformation of inorganic and organic sodium during fast pyrolysis of sodium-loaded lignin

This study employs a wire-mesh reactor (WMR) to understand the primary release and transformation of inorganic and organic sodium during fast pyrolysis of various sodium-loaded lignin samples at 300–800 °C. Due to the minimization of volatile-char interactions in WMR, the overall sodium release during lignin pyrolysis is relatively low, i.e., ∼9–11% and ∼7–14% for the inorganic and inorganic sodium loaded lignin, respectively. The presence of the inorganic sodium in the condensed volatiles (so-called oil) clearly indicates the important role of thermal ejection in the release of the inorganic sodium, since sodium salts are unlikely to evaporate under current conditions. While the release of the organic sodium into oil can be due to both thermal ejection of aerosols and evaporation of low carboxylates. Despite the low sodium release, significant transformation of the inorganic and organic sodium can take place during lignin pyrolysis. For the inorganic sodium loaded lignin, the inorganic sodium decreases continuously from ∼67% at 300 °C to ∼42% at 800 °C, accompanied by a steady increase in the organic sodium (i.e., the ion-exchangeable sodium) from ∼17% at 300 °C to ∼37% at 800 °C. While for the organic sodium loaded lignin, its transformation into the inorganic sodium is faster at higher temperatures, leading to a large increase in the inorganic sodium (i.e., carbonates) from ∼9% at 300 °C to ∼48% at 800 °C, as well as a reduction in the organic sodium from ∼79% at 300 °C to ∼28% at 800 °C. The data generated in this study will be important to understand the catalytic mechanism of sodium during thermochemical processing of alkali lignin for the production of bioenergy and biofuels.     

Effect of cellulose–lignin interactions on char structural changes during fast pyrolysis at 100–350 °C

This study investigates the cellulose–lignin interactions during fast pyrolysis at 100–350 °C for better understanding fundamental pyrolysis mechanism of lignocellulosic biomass. The results show that co-pyrolysis of cellulose and lignin (with a mass ratio of 1:1) at temperatures < 300 °C leads to a char yield lower than the calculated char yield based on the addition of individual cellulose and lignin pyrolysis. The difference between the experimental and calculated char yields increases with temperature, from ～2% 150 °C to ～6% at 250 °C. Such differences in char yields provide direct evidences on the existence of cellulose–lignin interactions during co-pyrolysis of cellulose and lignin. At temperatures below 300 °C, the reductions in both lignin functional groups and sugar structures within the char indicate that co-pyrolysis of cellulose and lignin enhances the release of volatiles from both cellulose and lignin. Such an observation could be attributed to two possible reasons: (1) the stabilization of lignin-derived reactive species by cellulose-derived reaction intermediates as hydrogen donors, and (2) the thermal ejection of cellulose-derived species due to micro-explosion of liquid intermediates from lignin. In contrast, at temperatures ≥ 300 °C, co-pyrolysis of cellulose and lignin increases char yields, i.e., with the difference between the experimental and calculated char yields increasing from ～1% at 300 °C to ～8% at 350 °C. The results indicate that the cellulose-derived volatiles are difficult to diffuse through the lignin-derived liquid intermediates into the vapor phase, leading to increased char formation from co-pyrolysis of cellulose and lignin as temperature increases. Such an observation is further supported by the increased retention of cellulose functional groups in the char from co-pyrolysis of cellulose and lignin.     

Molecular insight into soil carbon turnover

Curie-point pyrolysis-gas chromatography coupled on-line to mass spectrometry (Py-GC/MS) and isotope ratio mass spectrometry (Py-GC/IRMS) were used to determine the individual turnover rate of specific carbohydrates, lignin, lipids and N-containing compounds from French arable soils. The analysed soils were cultivated, either continuously with a C3 plant (wheat delta(13)C-value = -25.2 per thousand), or transferred to a C4 plant (maize delta(13)C-value = -11.4 per thousand) cropping 23 years ago. Most pyrolysis products identified were related to carbohydrates (furans), lipids (hydrocarbons and derivatives of benzene), proteins (nitriles and pyrrole) and lignins (phenols). The relative yield of all individual pyrolysis products was similar in the samples from the maize and control wheat soil. The isotopic enrichment between identical pyrolysis products from the two soils varied from 1 to 12 delta (delta) units, indicating that after 23 years of cultivation 7 to 90% of their C was derived from maize. This suggests a slow mean turnover time varying from 9 to 220 years. Based on the differences in isotopic enrichment of chemical structures after vegetation change the pyrolysis products could be divided into three groups: (i) pyrolysis products with a nearly complete C4 signal, e. g. phenol, derived from lignin degradation products, (ii) pyrolysis products with an intermediate isotopic enrichment of 6-8 per thousand, most likely to be a composite of remaining (possibly physically protected) fragments derived from both maize and native wheat, and (iii) pyrolysis products showing only low enrichments in (13)C of 1-3 per thousand. Most of their precursors were found to be proteinaceaous materials. This indicates that proteins or peptides are indeed preserved during decomposition and humification processes occurring in the soil. Our study highlights the potential of Py-GC/MS-C-IRMS to further novel insights into the dynamics of soil organic constituents. Copyright 1999 John Wiley & Sons, Ltd.     

紫外光谱法分析煤直接液化油族组成

煤液化油组成的测定方法以色谱法为主,但由于样品沸程长,组分性质不均一,色谱法无法实现简便快速地对液化油族组分进行定性/定量。为建立一种快速准确定量煤液化油中的酚类化合物、芳烃、脂肪烃的分析方法,本文选取具有代表性组成的煤液化油180～200 ℃馏分为研究对象,筛选了环己烷、乙醇、氢氧化钠-乙醇(50 Wt%,简称碱醇溶剂)三种分离溶剂。通过对煤液化油样品在200～400 nm波长间的特征吸收峰分析,发现碱醇溶剂可使芳烃化合物对酚类化合物的干扰减少到最小,可以有效避免吸收峰重叠问题。在此基础上,进一步对比分析了苯酚,间甲酚,邻甲酚,对甲酚等标准化合物与液化油酚类混合物在碱醇溶液中紫外吸收的标准曲线,以定量样品组成。选择间甲酚为标准化合物,根据其在290 nm处的标准曲线,得到煤液化油中酚类化合物的总量为32.14%,测定结果与宏量样品分离、称重、物料平衡后结果基本一致。在得到酚类化合物含量之后,以四氢萘为标准物,获得液化油中芳烃的总量为44.91%,脂肪烃的含量为22.95%。为确定方法的准确性,油样分别加入不同量的间甲酚和四氢萘标准物,酚的加标回收率为104.3～110.75%,芳香烃的加标回收率在84.3～91.75%。综上表明：利用紫外光谱法,以碱醇溶剂排除芳烃对酚吸收的影响,能够快速测定煤液化油中酚类和芳香烃的含量,脂肪烃的含量可差减得到。