Characterization of Oil Shales by High Pressure DSC

Pressurised differential scanning calorimeter (PDSC) has been used to obtain information on the pyrolysis and combustion characteristics of oil shales. Two distinct exothermic peaks were identified in combustion experiments known as low temperature oxidation (LTO) and high temperature oxidation (HTO) reaction regions. The pyrolysis process of all studied oil shale samples showed one exothermic effect at each total pressure studied. Kinetic data were analysed by Roger & Morris and Arrhenius methods and the results are discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

证实稀溶液蒸气压降低的简易方法

通过简单的实验方法, 证实稀溶液蒸气压降低的现象。并从微观角度, 对此现象加以解释。理论解释与实验现象结合, 能使学生对溶液的相关性质有更加深入的理解。     

Determination of kerogen type by using DSC and TG analysis

The rate of pyrolysis and oxidation of 8 different samples of oil shale kerogen concentrate (KC) were investigated using DSC analysis. Recently performed thermogravimetric studies (TG and DTG) with the same samples of KC indicated that the activation energy of the pyrolysis of specific KCs increases with increasing paraffinic structure in the KC. An opposite effect, i.e. a decrease of the activation energy with an increase of paraffinic structure was determined in the case of KC oxidation. In this study, using the standard ASTM E-698 method based on the determined temperature at which the maximum heat effect could be observed (exo in the case of oxidation and endo in the case of pyrolysis), an activation energy for the pyrolysis, as well as for the oxidation process was determined and also successfully correlated with the content of paraffinic structure of KC. Thus, the higher content of paraffinic structure in KCs indicates that higher values of the activation energy could be determined either in the case of pyrolysis or oxidation followed by DSC analysis.     

Determination of thermodynamic stability of CdMoO4 by knudsen effusion vapor pressure measurement method

Thermodynamic stability of CdMoO₄ was determined by measuring the vapor pressures of Cd and MoO₃ bearing gaseous species. Th vaporization reaction could be described as CdMoO₄(s)+MoO₂(s) =Cd(g)+2/n(MoO₃)_n (n=3, 4 and 5). The vapor pressures of the cadmium (p _Cd) and trimer (p _(MoO3)3) measured in the temperature range 987≤T/K≤1111 could be expressed, respectively, as ln (p _Cd/Pa) = –32643.9/T+29.46±0.08 and ln(p _(MoO3)3/Pa) = –32289.6/T+29.28±0.08. The standard molar Gibbs free energy of formation of CdMoO₄(s), derived from the vaporization results could be expressed by the equations: °_f G _{CdMoO4 (s)} ⁰= –1002.0+0.267T±14.5 kJ mol^–1 (987≤T/K≤1033) and °_f G _{CdMoO4 (s)} ⁰ = –1101.9+0.363T±14.4 kJ mol^–1 (1044≤T/K≤1111). The standard enthalpy of formation of CdMoO₄(s) was found to be –1015.4±14.5 kJ mol^–1 .     

Indirect Determination of Sulfide by Cold Vapor Atomic Absorption Spectrometry

A method for the determination of sulfide based on its interference with the determination of Hg by cold vapor atomic absorption spectrometry is described. The decrease in mercury absorbance at 253.7nm is proportional to the concentration of sulfide over the range of 10–320ngmL^–1. The limit of detection was found to be 7ngmL^–1 and the relative standard deviation (R.S.D.) for the determination of different concentrations of sulfide was in the range of 1.8–2.2%. This method was applied to the determination of sulfide in whole human blood after gas-phase separation.     

静态法和动态法测量乙醇饱和蒸气压的比较

物质的蒸气压是化学、化工、冶金、医药等领域的重要基础数据。测量饱和蒸气压是大学物理化学实验教学中的一个基础实验,测量方法主要有静态法和动态法,但两种方法的比较尚未见报道。本文通过比较,得出了两种方法的优缺点以及注意事项。     

Saturated Vapor Pressure of Iridium(III) Acetylacetonate

The temperature dependency of the saturated vapor pressure of Ir(acac)₃ has been measured by the method of calibrated volume (MCV), the Knudsen method, the flow transpiration method, and the membrane method. The thermodynamic parameters of phase transition of a crystal to gas were calculated using each of these methods, and the following values of ΔH _T ⁰ (kJ mol⁻¹) and ΔS _T ⁰ (J mol⁻¹K⁻¹), respectively, were obtained: MCV: 101.59, 156.70; Knudsen: 130.54, 224.40; Flow transpiration: 129.34, 212.23; Membrane: 95.45, 149.44 Coprocessing of obtaining data (MCV, flow transportation method and Knudsen method) at temperature ranges 110−200°C as also conducted:ΔH _T ⁰ =127.9±2.1 (kJ mol⁻¹ ); ΔS _T ⁰ =215.2±5.0 (J mol⁻¹ K⁻¹ ). This revised version was published online in August 2006 with corrections to the Cover Date.     

完全不互溶双液系的蒸气压*

对完全不互溶双液系的饱和蒸气压进行了实验研究与理论讨论,认为完全不互溶双液系的平衡蒸气压随两组分相互溶解度减小而趋于但总是小于两纯组分的饱和蒸气压之和;当完全不互溶两液相一起静置时,上层液体能有效但不能完全阻止下层液体的挥发,这种阻止作用源于缓慢溶解、扩散和挥发这些动力学过程;提出了阻止下层液体挥发的方法,即用与之完全不互溶且密度小的液体来覆盖,并且2种液体充满容器,阴凉处密闭静置保存。     

The Use of Isothermal Heat-Conduction Calorimetry in Direct Measurements of Solvent Vapor Pressure

Principles for applying isothermal heat-conduction calorimetry for direct studies of vapor/liquid equilibria are presented. The ideas have been tested by measurements of the vapor pressure of water over aqueous NaCl(aq) solutions at 25°C. Seven different stock solutions were used with a composition ranging from 0.0879 mol-kg^–1 to saturated solution. The imprecision and inaccuracy were not dependent on the composition and were found to be about ±2 Pa over the entire composition range. The sample solution was placed in a container separated from the pure solvent which was kept in the calorimetric cell. Solvent vapor was transported isothermally between the container and the cell by means of an inert carrier gas. The vapor pressure was evaluated by measuring the heat-flow rate associated with the process where the vapor equilibrated with a NaCl(aq) solution is fully saturated by passing through pure solvent. Corrections for treating vapor phase imperfections are presented. The method was found to be fast, accurate, and easy to use. The concept developed here can easily be applied in any commercial heat-conduction calorimeter of modular design.     

DSC Study of the Effects of High Pressure and Spray-Drying Treatment on Porcine Plasma

One use of blood generated in abattoirs is to obtain dehydrated plasma which can be used as a functional ingredient in the preparation of foods. High hydrostatic pressure is a new technique for improvement of the sanitary quality of food products or their ingredients. The changes caused in the proteins by treatment can affect their functional properties, and differential scanning calorimetry DSC was therefore applied to detect possible conformational changes in the plasma proteins. The DSC results in the present study show that spray-drying does not appreciably affect the protein structure, but high-pressure treatment seems to have a denaturing effect. This revised version was published online in July 2006 with corrections to the Cover Date.     

Determination of oxidation parameters of fatliquored leather by DSC

The oxidation of a number of fatliquoring formulations, of different iodine index, derived from fish oil, rapeseed oil, neatsfoot oil, lecithin, paraffin, sulphited and sulphated variants was studied. The formulations included dispersing agents, stabilizers and/or anti-oxidants. Sheepskins were treated with fatliquoring agents at 5% of fatty matter. The oxidation of the fatliquoring formulations and the fatliquored skins was studied by non-isothermal differential scanning calorimetry (DSC). The onset thermoxidation temperature and the enthalpy of the thermoxidation peak located between 195 and 265 °C were determined and then related to the different fatliquoring standard formulations. The skins were subjected to ageing treatments using UV radiation and temperature. The fall in the denaturation temperature of the skin due to ageing was related to the oxidability of the fatliquoring agent.     

饱和蒸气压测定实验中气流量调控装置的改进

In the static method of saturated vapor pressure measurements, the key operation is to adjust the pressure of the system. Because of the invisibility of the gas, it is difficult to control the air flow, which often results in air pouring into the system due to excessive air flow in the constant pressure adjustment process. By designing a mini gas flow control device, the control operation is visualized; thus, problems associated with controlling the air flow can be avoided. Furthermore, frequent adjustment of the air flow becomes unnecessary, greatly reducing the lab hour.     

Saturated Vapor Pressure and Crystal Structure of Bis-(2-imino-4-pentanonato)copper(II)

A comprehensive study of copper(II) bis-ketoiminate including tensimetric analysis of sublimation and structure solution has been carried out. The temperature dependence of saturated vapor pressure over Cu(ki)₂ crystals derived by the flow method is expressed by the equation lnP_(atm)} = 25.31-13750/T, H _subl = -114.2 ± 1.3 kJ· mole^-1, S_subl =210.2 ± 3.0> J· mole^-1 · K^-1. Crystal data for CuO₂N₂C₁₀H₁₆: a=15.143(3), b=16.681(8), c=13.795(32) , space group Ccca, Z=12, d _calc = 1.47 g/cm³, R=0.029. The structure is molecular and consists of crystallographically independent Cu(ki)₂ complexes of two types, one with a cis structure and the other with a cis–trans disordering. The copper atom has a plane square environment of two oxygen and two nitrogen atoms. In the cis isomer, Cu–O 1.938 and Cu–N 1.895 ; in the disordered complex, all four Cu–O(N) distances are 1.901 .     

In Defense of Vapor Pressure Osmometry for Measuring Molecular Weight

The value of the average molecular weight of petroleum asphaltenes continues to be controversial. Usually the disagreement is about the measurement of a single asphaltene fraction when the need is for a consistent picture that comprises all fractions of petroleum and includes chemical changes during processing. By using one of the better solvents for carbonaceous materials, o‐dichlorobenzene, at the maximum instrument temperature, vapor pressure osmometry provides a consistent measurement of number average molecular weight not achieved by any other technique. This average molecular weight is consistent among petroleum fractions and gives predictable changes in asphaltene molecular weight with thermal processing.     

含盐体系汽液平衡的测定方法和测定仪器的研究

针对含盐体系汽液平衡测定的特点及常用测定仪器和方法中的问题，改制了具有沸点仪和双循环平衡釜双重功能CS－Ⅱ型VLE测定仪，并以拟表态法测定了含盐体系汽液平衡的泡点线和平衡液相恒盐浓度下的露点线，新测定仪能避免用双循环仪器时极易出现的流动不稳定性和爆沸现象，成功地测定了氯化钙平衡液相浓度为5％的CaCl2-丙酮（1）－甲醇（2）体系的汽液平衡数据。     

新型调压装置在液体饱和蒸气压测定实验中的应用

引入可控进气量和具有独立操作的增、减压缓冲瓶的调压装置,使气压调节缓慢可控,能连续调节缓冲瓶内气体压力以适应不同温度点的液体饱和蒸气压;可通过控制U形液柱缓慢移动来读取气液平衡状态下饱和气压值,较好地克服了以往实验中存在的调压操作困难、易发生空气倒灌及未知蒸气饱和的问题,取得了良好的实验效果,提高了实验数据的准确性。     

昆虫信息化合物相对蒸气压的气相色谱分析

报道了用０１２％胆固醇对氯肉桂酸酯（ＣＰＣＣ）和００８％ＯＶ１０１液晶相毛细管柱气相色谱法测定化合物相对蒸汽压的方法及对６０个昆虫信息化合物相对蒸汽压的测定结果。由此可直接利用公式计算昆虫信息素各组分的释放速率。使合成信息素最佳配比的选择方法大为简化。     

Quantitative Determination of Crystallinity of α-Lactose Monohydrate by DSC

In pharmaceutical practice it is important and useful to know the crystallinity of materials and to monitor it during formulation development, production processes and storage. The purpose of this study was to assess the quantitative capability of DSC for determining crystallinity in crystalline/amorphous powder mixtures and to compare the accuracy of the DSC method with that of conventional powder X-ray diffraction. Alpha-lactose monohydrate was chosen as the model material. On the basis of this study it can be concluded, that DSC method can be applied safely for semiquantitative evaluation of the crystallinity of lactose samples consisting of an amorphous content higher than 20%. This revised version was published online in August 2006 with corrections to the Cover Date.     

纯液体饱和蒸气压测定实验的改进

对纯液体饱和蒸气压测定实验进行了装置创新设计,该装置解决了该实验的一些关键问题:保证相平衡时的气相为纯液体蒸气;准确测定相平衡时的温度;方便有效地调节外压与液体蒸气压相等。改进后的装置设计合理,操作简单、快捷,消除了安全隐患,大大缩短了实验时间,可一人单独操作。