红外光谱法直接鉴别苦丁茶的研究

本文利用傅立叶变换红外光谱(FTIR)法快速、直接地测定了11种苦丁茶,并对所获得的指纹图谱进行特征峰指认和对比分析。结果表明:各种苦丁茶化学成分相同,而由于各成分间的相对含量的不同,使每种样品都有自己独特的红外谱图,不同产地、不同级别苦丁茶的红外吸收频率、吸收峰的相对强度都存在比较大的差异。同时还运用傅立叶变换红外光谱技术对不同产地、不同级别苦丁茶的混合化学体系进行了全组分快速分析,为苦丁茶的鉴别及质量控制提供了可靠的依据。     

不同方法预处理的玉米秸秆结构与酶解分析

在利用秸秆进行工业转化时,因为秸秆结构复杂,导致转化效率低,所以需对秸秆进行预处理,破坏秸秆复杂结构,提高转化效率。采用扫描电镜(SEM)、傅里叶变换红外光谱(FT-IR)和X射线衍射技术分析不同预处理方式对玉米秸秆微观结构的影响,并利用纤维素酶对不同预处理秸秆进行酶解,评价预处理效果。扫描电镜结果表明,不同预处理方式对秸秆表面形态和秸秆整体结构造成不同程度的破坏,其中NaOH预处理后的秸秆表面结构坍塌明显,表明木质纤维素结构被有效打破。利用傅里叶变换红外光谱对不同预处理方式的秸秆进行分析,其中1600和1510cm~(-1)为木质素的特征峰,NaOH预处理后的秸秆在此处的特征峰基本消失,表明NaOH预处理对秸秆木质素的去除效率比较明显。1744~1734 cm~(-1)为C=O伸缩振动特征峰,此峰的强度与木质素和半纤维素的含量有关,采用不同方法预处理后,此峰的吸收强度不同程度地减少,表明各种预处理方法不同程度地去除了秸秆的木质素和半纤维素。X-射线衍射分析表明,不同预处理后秸秆的结晶度均发生不同程度的改变,其中H_2SO_4预处理后秸秆的结晶度提高最大,达到43.4%。其中NaOH预处理秸秆后,用纤维素酶酶解60h,使其酶解产糖量达到33.32g/L。本研究分析了不同秸秆预处理方法的效果,为利用玉米秸秆生产生物化工产品提供了理论依据。     

衰减全反射红外光谱法测定电工胶带粘合剂

采用衰减全反射傅里叶变换红外光谱法(ATR-FTIR)对31个品牌电工胶带的粘合剂进行分析,通过红外特征吸收峰确定粘合剂的主要成分均为天然橡胶和丁苯橡胶混合物,不同品牌的样品通过红外光谱定性分析无法区分。通过OPUS软件分别选择天然橡胶和丁苯橡胶的红外特征吸收峰进行峰面积积分,计算两种物质特征峰面积的相对比例,采用单因素方差分析确定不同样品天然橡胶和丁苯橡胶特征峰面积的相对比例是否存在统计学差异,然后采用最小显著性差异法进行验后多重比较,分析特征峰面积相对比例存在统计学差异的品牌。31个品牌电工胶带组成的465组样品对中有422组可以区分,区分率达到90.8%。结果表明,通过红外光谱定量分析可实现不同品牌电工胶带粘合剂的区分。     

气相色谱-质谱联用分析白兰叶油成分

采用气相色谱－质谱联用技术对苏州产白兰叶油的化学成分进行了分析,分离出３３个峰。鉴定了其中２７种成分,占总峰面积的９７％,并对油中的主要化学成分芳樟醇用气相色谱－傅立叶红外光谱法进行了验证。     

超高效液相色谱-四极杆飞行时间质谱分析不同加工何首乌中差异化学成分

建立了超高效液相色谱-四极杆飞行时间质谱(UPLC-QTOF-MS)结合多元统计分析技术对不同加工何首乌中化学成分差异的分析方法。何首乌样品采用甲醇在室温下超声提取后,采用UPLC-QTOF-MS进行分析,对采集的图谱通过峰匹配、峰对齐、滤噪处理等进行特征峰提取,然后用主成分分析(PCA)和偏最小二乘法-判别分析(PLS-DA)对数据进行分析。结果显示,不同加工何首乌样品间的化学组成存在显著性差异;根据一级质谱精确质荷比和二级质谱碎片信息,结合软件数据库搜索及相关文献进行成分鉴定,初步筛选并鉴定出33种不同加工何首乌间差异显著的化学成分,其中15种为共有差异化学成分,并呈现出不同的变化规律。研究结果可为揭示不同加工方法对何首乌代谢产物差异性的影响规律提供依据。     

不同产地鲍鱼的FTIR谱图分析

为了寻找能够鉴别不同产地鲍鱼成分差异的新方法,利用傅里叶变换红外光谱(FTIR)测定不同产地的鲍鱼样品,对所获得的指纹图谱进行对比分析,初步探讨鲍鱼区域性之间的差别.结果表明:这3个产地鲍鱼红外吸收峰的峰数、峰位、峰形、峰强都存在一定程度的差异,为鉴别鲍鱼产地提供了一种有效的手段.     

蒙药荜茇不同提取物的红外光谱

采用傅里叶变换红外光谱法(FT-IR)并借助于二阶导数谱研究了蒙药荜茇原药材及不同溶剂提取物(采用石油醚,95%乙醇和水)所含化学成分的红外谱图整体变化规律。结果表明:荜茇石油醚提取物的红外光谱图可见羰基的吸收峰(1722 cm~(-1))和亚甲基的吸收峰(2927和2855 cm~(-1))比较强,说明其中所含大量的小分子萜类、脂肪酸(酯)等低极性成分;95%乙醇提取物中可能含有芳酮类化合物及糖苷类化合物。水提取物中主要含鞣质及多糖类成分。FT-IR能够简便、快速地提供蒙药不同提取物中主要化学成分的信息,可对其主体成分进行初步的识别,为制定下一步的提取方案和检测方法提供了方向性参考。     

红外指纹图谱与双指标模型结合用于白芷品质分析

利用共有峰率和变异峰率两个指标,鉴别了不同品质的白芷的红外指纹图谱,白芷样品按厂家各自聚为一类。并应用化学计量学中模式识别方法,即主成分分析和系统聚类分析法,对白芷样品共有特征高效液相色谱峰数据进行处理。主成分分析和系统聚类分析结果与双指标模型一致,川白芷与祁白芷共有峰率最高,达到83. 3%。运用红外指纹图谱与双指标模型结合的方法,可以对白芷进行简单快速准确鉴别,为白芷品质的评价提供了另一种思路。     

分析测试新成果(238~242)电线塑料护套的傅立叶变换红外光谱分析

采用傅立叶变换红外光谱法对21个5种不同颜色的电线塑料护套样品进行了分析.从红外光谱图中可观察到样品特征峰的峰数、峰位、相对峰面积比均有差异,但可以归纳为两大类.其中同种颜色的不同样品在红外谱图中又反映出了不同的信息,这表明在外观颜色十分相近的情况下,采用此方法能够有效的为刑事案件现场遗留的各种塑料制品提供鉴别与比对.     

马山前胡挥发油化学成分研究

本文用毛细管气相色谱、气相色谱／质谱／计算、气相色谱／红外光谱等现代仪器分析技术，对马山前胡挥发油的化学成分进行了分析研究，从毛细管色谱分离出８０多个峰，确认了其中３７种成分，占色谱总馏出峰面积的９７％以上，该挥发油的主要化学成分为蒎烯。     

Contamination of wheat, rye, and potatoes by foliar application of134Cs

The aim of the study reported in this paper was to derive factors describing the translocation of radiocesium from the green plant parts to the crop. Wheat, rye and potatoes were contaminated and harvested at different growth stages to allow the assessment of the contamination of the crop with known date of the radioactive deposition. At harvest, the cesium concentrations in the crop, the green plant parts (i.e., straw without ears) and the roots were measured. The results show that the contamination of the crop depends strongly on the date of¹³⁴Cs application and on the type of plants. The highest translocation was observed when cesium was applied during flowering.     

Changes to the physicochemical characteristics of wheat straw by mechanical ultrafine grinding

To investigate changes on the physicochemical characteristics of wheat straw by mechanical ultrafine grinding, wheat straw powders of four different particle sizes and distributions were produced using a sieve-based Retsch ZM100 grind mill and CJM-SY-B ultrafine vibration grind mill. Changes on the microstructure and physicochemical characteristics of the different powders were assessed by scanning electron microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and relevant standard laboratory analysis methods. Ultrafine grinding reduced the crystallite size and crystallinity of the wheat straw. New surfaces were exposed on the ultrafine powder with high levels of cellulose/hemicelluloses components but there was no apparent change in chemical structure. Wheat straw powders were smaller in size but had a higher bulk density (from 0.19 to 0.54 g/mL) and angle of repose (from 46.02° to 55.61°) and slide (from 37.26° to 41.00°). The hydration properties (water-holding capacity and swelling capacity) decreased with reduction in particle size of the wheat straw. Both the sieve-based and ultrafine powder exhibited a good ability to remove Pb²⁺ and Cd²⁺ and there was marginal improvement when using the ultrafine powder. The thermal stability of the ultrafine powder measured by thermogravimetric analysis decreased significantly because of the low cellulose crystallinity.     

A sustainable approach for soil amendment; available plant nutrients in rice straws

The main aim of this study is to estimate the potential of mitigating the soil degradation by the utilization of rice straws, In every crop huge quantity of crop residue is generated along with the food grains. Only small part of the crop residue is used as cattle feed and other applications, significant quantity of these crop residues are either left unutilized or disposed by means of open field burning by the farmers, because other disposal options are not economically viable for the farmers. Consequences of open field burning of crop residues in India are, contribution of particulate matter in the atmosphere, emission of CO₂, CO, NH₃, NO_x, SO_x, and smog. On burning of crop residue heat produced is also accounted for the damage of microbes and other nutrients also present on the top layer of the soil, loss of organic carbon; it adversely affects soil fertility and productivity. It has a great economic potential as it contains high carbon content and significant amount of other essential plant nutrients which are required for plant growth. Sun dried rice straw samples were collected and analysed for primary nutrients (C, H, S, N, P₂O₅ and K₂O) required for plant growth. Moisture content was 11.70%, Elemental analysis of paddy straw on dry basis was found C = 36.04%, H = 5.25%, S = 0.28% & N = 0.69% P₂O₅ = 0.43% and K₂O = 0.64% in the kharif season 2021. These elements were quantified by using different advanced analytical techniques.     

利用麦秆制聚氨酯多元醇研究

以小麦秸秆为原料,在浓硫酸催化作用下以聚乙二醇(PEG400)为液化试剂进行液化,讨论了麦秆纤维粒径、催化剂用量、乙二醇(EG)加入量、反应温度和时间等因素对液化残渣率的影响.结果表明:当纤维为"＞12目",EG用量为20%,浓硫酸用量为4%,在160℃下反应60min时,所得残渣率最小,为0.8%.羟值、酸值的测试结果和红外分析结果表明,液化过程中羟值逐渐减小,而酸值则呈现先增大后减小的趋势,说明反应后期有酯缩合反应发生.将液化产物与二苯基甲烷二异氰酸酯(MDI)反应可制成泡沫材料,红外光谱证实生成物具有聚氨酯的典型特征.得到的泡沫材料密度为38kg/m3,抗压强度为118kPa,性能优良.     

An experimental investigation into the gasification reactivity and structure of agricultural waste chars

The gasification reactivity as well as physical and chemical structure of chars generated from two kinds of agricultural waste (i.e. corn straw and wheat straw) were studied to better understand the role of lower pyrolysis temperatures and lower heating rates on the gasification characteristics of agricultural waste chars. Char samples were generated in a one-stage quartz fixed-bed reactor. The carbon dioxide (CO₂) gasification reactivity of chars was measured by thermogravimetric (TGA) analysis. Scanning electron microscopy (SEM) analysis, surface area (BET) analysis, Fourier transform infrared spectroscopy (FTIR) analysis and X-ray diffractometry (XRD) analysis were employed to determine the effect of operating conditions on the char structure. Char gasification reactivities decreased with increasing pyrolysis temperatures. The char particles generated under high pyrolysis temperatures had many smaller pores with thinner cell walls, larger surface areas, and some melting. Results indicated that many functional groups’ bands decreased and even disappeared with an increasing pyrolysis temperature. The chars’ microcrystalline became larger at high pyrolysis temperatures. The reactivity of wheat straw char is higher than corn straw char. The difference in the gasification reactivity of agricultural waste chars generated at different pyrolysis temperatures correlated well with the effect of pyrolysis temperatures on the agricultural waste char structure.     

Oxidation in Acidic Medium of Lignins from Agricultural Residues

Agricultural residues as sugarcane straw and bagasse are burned in boilers for generation of energy in sugar and alcohol industries. However, excess of those by-products could be used to obtain products with higher value. Pulping process generates cellulosic pulps and lignin. The lignin could be oxidized and applied in effluent treatments for heavy metal removal. Oxidized lignin presents very strong chelating properties. Lignins from sugarcane straw and bagasse were obtained by ethanol–water pulping. Oxidation of lignins was carried out using acetic acid and Co/Mn/Br catalytical system at 50, 80, and 115 °C for 5 h. Kinetics of the reaction was accomplished by measuring the UV-visible region. Activation energy was calculated for lignins from sugarcane straw and bagasse (34.2 and 23.4 kJ mol⁻¹, respectively). The first value indicates higher cross-linked formation. Fourier-transformed infrared spectroscopy data of samples collected during oxidation are very similar. Principal component analysis applied to spectra shows only slight structure modifications in lignins after oxidation reaction.     

Effect of mineral matter on the formation of NOX precursors during biomass pyrolysis

Formation of NO_X precursors during pyrolysis of three typical kinds of biomass (wheat straw, rice straw and corn cob) was studied using a thermogravimetric analyzer (TGA) coupled with a Fourier transform infrared (FTIR) spectrometer in argon atmosphere. Two pretreatment methods, including deionized water washing and acid washing were utilized to investigate the effect of included minerals on the distribution of nitrogen containing species during wheat straw pyrolysis. KOH and CaO were loaded onto the demineralized (dem) wheat straw to study the effect of excluded minerals on nitrogen release. The residues of the samples after pyrolysis were characterized by X-ray diffraction (XRD) analysis. The results show that different kinds of biomass have distinctive formation characteristics of N-containing species. HCN and HNCO are the main N-containing species for rice straw, while NH₃ and HCN are the main N-containing species for wheat straw and corn cob.The existence of minerals influences the formation of N-containing species during biomass pyrolysis. Both the included potassium and excluded potassium promote N-conversion to NH₃, HCN, NO and HNCO at lower temperature, but decrease the total yields of N-containing species. The included calcium decreases N-conversion to HCN, NH₃ and HNCO at lower temperature (<about 330 °C), while favors the total yields of N-containing species. However, the presence of added calcium restrains N-conversion to HCN, NH₃, NO and HNCO.     

水稻秸秆石油醚和乙醇萃取物的组成分析

用石油醚和乙醇在索式萃取器中对水稻秸秆进行了萃取,萃取物用傅里叶转换红外光谱仪（FTIR）和气相色谱 质谱联用仪（GC/MS）分析。 结果表明,乙醇和石油醚的萃取率分别为8%和6%。 萃取物中共检测到40种物质,主要分为醇酚（APs）、醛、酮、酸、酯、烃（HCs）及含氮化合物（ONs）7种类别。 其中,石油醚萃取物中酯、HCs和APs 3类物质含量较高,总的相对含量为91.7%;乙醇萃取物中HCs、酸、酯及APs含量较高,总的相对含量为83.9%。 该研究在开发稻秆的高附加值利用方面具有重要的基础理论意义。     

Cellulose and microcrystalline cellulose from rice straw and banana plant waste: preparation and characterization

As part of continuing efforts to prepare cellulose and microcrystalline cellulose (MCC) from renewable biomass resources, rice straw and banana plant waste were used as the available agricultural biomass wastes in Egypt. The cellulose materials were obtained in the first step from rice straw and banana plant waste after chemical treatment, mainly applying alkaline-acid or acid-alkaline pulping which was followed by hypochlorite bleaching method. The results indicate a higher α-cellulose content, 66.2 %, in case of acid-alkaline treatment for rice straw compared to 64.7 % in case of alkaline-acid treatment. A low degree of polymerization, 17, was obtained for the cellulose resulting from acid–alkaline treatment for banana plant waste indicating an oligomer and not a polymer, while it reached 178 in case of the cellulose resulting from alkaline–acid treatment for the rice straw. MCC was then obtained by enzymatic treatment of the resulting cellulose. The resulting MCC show an average diameter ranging from 7.6 to 3.6 μm compared to 25.8 μm for the Avicel PH101. On the other hand, the morphological structure was investigated by scanning electron microscopy indicating a smooth surface for the resulting cellulose, while it indicates that the length and the diameter appeared to be affected by the duration of enzyme treatment for the preparation of MCC. Moreover, the morphological shape of the enzyme treated fibers starts to be the same as the Avicel PH101 which means different shapes of MCC can be reached by the enzyme treatment. Furthermore, Fourier transform infrared spectroscopy was used to indicate characteristic absorption bands of the constituents and the crystallinity was evaluated by X-ray diffraction measurements and by iodine absorption technique. The reported crystallinity values were between 34.8 and 82.4 %, for the resulting cellulose and MCC, and the degree of crystallinity ranged between 88.8 and 96.3 % dependent on the X-ray methods and experimental iodine absorption method.     

Preparation and Characterization of MgO-Modified Rice Straw Biochars

Rice straw is a common agricultural waste. In order to increase the added value of rice straw and improve the performance of rice straw biochar. MgO-modified biochar (MRBC) was prepared from rice straw at different temperatures, pyrolysis time and MgCl₂ concentrations. The microstructure, chemical and crystal structure were studied using X-ray diffraction (XRD), a Scanning Electron Microscope (SEM), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption desorption isotherms and Elementary Analysis (EA). The results showed that the pyrolysis temperature had significant influence on the structure and physicochemical property of MRBCs. MRBC-2 h has the richest microporous structure while MRBC-2 m has the richest mesoporous structure. The specific surface area (from 9.663 to 250.66 m²/g) and pore volume (from 0.042 to 0.158 cm³/g) of MRBCs increased as temperature rose from 300 to 600 °C. However, it was observed MgCl₂ concentrations and pyrolysis time had no significant influence on pore structure of MRBCs. As pyrolysis temperature increased, pH increased and more oxygen-containing functional groups and mineral salts were formed, while MgO-modified yield, volatile matter, total content of hydrogen, oxygen, nitrogen, porosity and average pore diameter decreased. In addition, MRBCs formed at high temperature showed high C content with a low O/C and H/C ratios.