高浓度V-H2O体系的溶解组分优势区域图和Pourbaix图

对25 ℃, 总V浓度cT(V)=1.0×10^-3 mol·L-1时的V-H2O 体系可能存在的组分进行热力学和电化学分析, 计算了各溶解组分的浓度, 运用“浓度比较法”作为判据, 确定液相和液相、液相和固相以及各固相间的边界线, 绘制了cT(V)=1.0×10^-3 mol·L-1时V-H2O 体系的溶解组分优势区域图和Pourbaix图. 与低浓度(cT(V)=1.0×10^-5 mol·L-1)的优势区域图比较发现, 在一定的温度和压力下, 总钒浓度对于钒阳离子的优势区影响不大, 但对钒酸根阴离子的优势区影响显著; 随着总钒浓度的增大和酸化程度的逐步加强, 钒酸根阴离子会发生一系列复杂的质子化和聚合反应; 总钒浓度越高、酸性越强, 多核钒酸根阴离子越稳定.     

高浓度V-H2O体系的溶解组分优势区域图和Pourbaix图

对25℃,总V浓度CT(V)=1.0x10-3 mol·L-1时的V-H2O体系可能存在的组分进行热力学和电化学分析,计算了各溶解组分的浓度,运用"浓度比较法"作为判据,确定液相和液相、液相和固相以及各固相间的边界线,绘制了CT(V)=1.0x10-3 mol·L-1时V-H2O体系的溶解组分优势区域图和Pourbaix图.与低浓度CT(V)=1.0x10-5mol·L-1)的优势区域图比较发现,在一定的温度和压力下,总钒浓度对于钒阳离子的优势区影响不大,但对钒酸根阴离子的优势区影响显著;随着总钒浓度的增大和酸化程度的逐步加强,钒酸根阴离子会发生一系列复杂的质子化和聚合反应;总钒浓度越高、酸性越强,多核钒酸根阴离子越稳定.     

电势-pH图的绘制和应用

从电势-pH图可以直观地了解元素及其化合物的某些性质和稳定存在的条件,本文简要介绍Fe-H2O系统的电势-pH图中典型电对的电势-pH线,为学生全面了解其他元素的电势-pH图打下基础     

盐酸普罗帕酮的示波测定

在0.5mol·L -1的NaOH底液中 ,盐酸普罗帕酮在示波计时电位图阴极支产生1个灵敏的切口 ,其二次微分简易示波图上峰高随盐酸普罗帕酮浓度增大而增高 ,可用于定量分析 ;线性范围为2.5×10-6～2.7×10 -5mol·L -1 ,回归方程为h(V)=127.0 +4.48×106c(mol·L -1) ,r=0.9981 ,检出限为1.0×10 -6mol·L-1;对9.000×10-6 mol·L-1 盐酸普罗帕酮5次测定的RSD为2.8 % ,回收率100.6 % ;与高效液相色谱和其他方法相比 ,本法具有仪器简单、方法简便快速、无需通氮除氧等特点。     

方波伏安法测定镍铜合金中的镍含量

在0.01mol·L-1的氨水-氯化铵缓冲溶液(pH 9.3)中,镍(Ⅱ)于-1.25V(vs.SCE)出现一灵敏的方波伏安峰。镍(Ⅱ)浓度在1.5×10-6～1.0×10-4mol·L-1与伏安峰高呈线性关系,线性方程为ip(μA)=2.1870+0.6328c(μmol·L-1),相关系数为0.9991。方法的标准偏差为0.7％。该法应用于镍铜合金样品中镍的测定,结果满意。     

马来酸麦角新碱的示波极谱测定方法的研究

在0.15 mol·L-1 HCl底液中,马来酸麦角新碱在-0.68 V(vs.SCE)处产生灵敏的极谱吸附波,二阶导数波峰电流与马来酸麦角新碱浓度在1.0×10-8~1.0×10-7及1.0×10-7~1.0×10-6mol·L-1范围内呈良好的线性关系,检出限为7.0×10-9 mol·L-1,用于片剂中马来酸麦角新碱的测定,结果良好。     

流动注射不可逆双安培法测定二苯胺磺酸盐

通过配合0.5mol·L-1硫酸溶液中二苯胺磺酸根在一支铂电极上的氧化和0.05mol·L-1硫酸溶液中高锰酸根在另一支铂电极上的还原,构建了类似可逆电对的双安培检测体系,在两铂电极间电位差为OV时,实现了流动注射不可逆双安培法测定二苯胺磺酸盐。二苯胺磺酸盐溶液和高锰酸钾溶液被隔离在两个用盐桥相连的电极室中,以避免两者发生化学均相反应。在试验条件下,回路电流与二苯胺磺酸根的浓度在2.0×10-6-2.0×10-4mol·L-1范围内呈线性关系,检出限为7.0×10-7mol·L-1(S／N=3)。连续11次测定1.0×10-5mol·L-1二苯胺磺酸钠,电流值的RSD为0.52％。方法简单快速,可用于工业产品中二苯胺磺酸盐的测定。     

浓碱溶液中生成高铁酸盐的玻碳电极循环伏安法表征(英文)

用玻碳电极研究了与Fe(Ⅵ)／Fe(Ⅲ)电对氧化还原有关的循环伏安曲线.所研究的体系是13mol·L-1NaOH中浓度范围分别为0.015～0.06mol·L-1的Na2FeO4和0.01～0.025mol·L-1的NaFeO2溶液。另一类研究体系是胶体石墨分别与固体K2FeO4、固体KFeO2组成的混合物,将这些混合物粘附于玻碳电极表面后在13mol·L-1KOH中进行循环伏安曲线的测定。结果证明了峰电位在0.7～1.0V的阳极电流峰与峰电位在0.15～0.2V(均相对于13mol·L-1NaOH或13mol·L-1KOH溶液中的Hg／HgO参比电极)的阴极电流峰,分别与高铁酸盐的生成与还原相对应。确定了将高铁酸盐的阳极生成电流峰与阳极析氧电流峰区别开来的条件。     

β-环糊精用于盐酸金刚烷胺的示波极谱测定

在0.2mol·L-1NaOH底液中,β-环糊精能够产生灵敏切口,其深度随盐酸金刚烷胺-β-环糊精包结物量的增加而变浅。根据β-环糊精的示波特性,建立了用二次微分简易示波伏安法间接测定片剂中盐酸金刚烷胺含量的新方法。盐酸金刚烷胺的浓度在1.0×10-6-3.6×10-5mol·L-1范围内呈线性,回归方程h(V)=97.66+7.27×105c(mol·L-1),相关系数为0.995 6,检出限为4.0×10-7mol·L-1。对于2.5×10-5mol·L-1盐酸金刚烷胺钠5次测定的RSD为3.1％。与其他方法相比,此法具有仪器简单、快速、无需通氮除氧等特点。     

线性扫描极谱法测定微量肉桂酸

在 1mol·L-1HOAc NaOAc介质中 (pH =3.6 ) ,肉桂酸有一还原峰 ,其峰电位为 - 1.4 7V(vs.SCE)。峰电流与肉桂酸浓度在 2 .0× 10 -5～ 8.0× 10 -4 mol·L-1之间呈线性关系 (r =0 .9989) ,检出限为 1.0× 10 -5mol·L-1。该法应用于肉桂酸含量的测定 ,结果满意 ,并对肉桂酸的电化学性质进行了研究     

X-Ray Mapping and Interpretation of Scatter Diagrams

Electron beam induced quantitative X-ray mapping has become a very useful characterisation tool for determining the elemental distribution in materials, whether using energy dispersive spectroscopy or wavelength dispersive spectroscopy. The X-ray intensity distributions of the elements from an X-ray map allow us to generate two dimensional and ternary scatter diagrams thus converting spatial information into concentration dimensions, which is an important tool for displaying the spatial relationships of elements or correlated elements (phases) in materials. To best understand how to use this tool, we need to understand the production and features of the scatter diagram. The type of clustering observed in the scatter diagram, whether oval, linear or spherical, can give the major and trace element distributions within phases as well as qualitative and quantitative phase information. This paper demonstrates the generation of scatter diagrams, properties of scatter diagrams, interpretation of scatter diagrams and the advantages of scatter diagrams through the use of examples.     

Structural Features of Solid Phases and Topology of Phase Diagrams

The paper considers model phase diagrams of binary and ternary systems involving transformations (transitions) of phase equilibria. The relationship between the type of structural solidstate transformation and the type of phase diagram is shown. Topological series of phase diagrams of systems with continuous and limited types of solid solutions are considered, including phase diagrams with polymorphic transitions between intermediate solid phases of variable composition.     

Analytic calculation of phase diagrams for solutions containing colloids or globular proteins

Second-order Barker–Henderson perturbation theory gives phase diagrams for colloid and protein solutions that include stable and metastable fluid–fluid, solid–fluid, and solid–solid phases. The potential of mean force is described by a hard-sphere interacting with a Yukawa potential. Calculations for different ranges of attraction show that, as expected, fluid–fluid coexistence becomes metastable when the potential becomes short-ranged. For a very short-ranged Yukawa potential, the phase diagram shows isostructural solid–solid equilibria with a critical point. To test more simplified models, phase diagrams from second-order Barker–Henderson perturbation theory are compared with those from the random-phase approximation for the fluid phase and the van der Waals theory for the solid phase; this comparison shows significantly different phase diagrams. Moreover, with a potential of mean force with primary and secondary minima, calculations using second-order perturbation theory identify conditions where colloidal and protein solutions can present two fluid–fluid regions, each with a critical point; however, the higher-density fluid–fluid region is likely to be metastable. The analytic calculations described here may be useful for interpretation of experimental phase diagrams and for guiding design of separation processes.     

Solid state phase transformations during the oxidation of copper sulfides: Roaster diagrams for the Cu-S-O system

Roaster diagrams that represent the stabilities of condensed phases as a function of temperature and percent oxygen appear to be more useful than the predominance area diagrams (PADs), which show the stability of different phases in the metal-sulfur-oxygen system at constant temperature. Roaster diagrams can be obtained from PADs and represent the intersection of total pressure lines with lines on a PAD extended in temperature. In this paper, PADs at four different temperatures and roaster diagrams for the system Cu-S-O are derived from PADs at total pressures of 0.25 atm and 1 atm. These diagrams show that at total pressures of 0.25 atm and 1 atm the CuO/CuO·CuSO₄ phase transformation occurs at 1063 K and 1133 K at 50% oxygen. The more complex four-component system Cu-As-S-O will follow in a subsequent publications.     

Determination of High Pressure Phase Diagrams of the Ternary Alloy System

ＤｅｔｅｒｍｉｎａｔｉｏｎｏｆＨｉｇｈＰｒｅｓｓｕｒｅＰｈａｓｅＤｉａｇｒａｍｓｏｆｔｈｅＴｅｒｎａｒｙＡｌｌｏｙＳｙｓｔｅｍＳＯＮＧＬｉ－ｚｈｕ；ＹＡＮＧＨｕａａｎｄＺＨＡＯＭｕ－ｙｕ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ，ＪｉｌｉｎＵｎｉｖ...     

Synthesis, characterization, and reactivities of manganese(V)-oxo porphyrin complexes

The reactions of manganese(III) porphyrin complexes with terminal oxidants, such as m-chloroperbenzoic acid, iodosylarenes, and H(2)O(2), produced high-valent manganese(V)-oxo porphyrins in the presence of base in organic solvents at room temperature. The manganese(V)-oxo porphyrins have been characterized with various spectroscopic techniques, including UV-vis, EPR, 1H and 19F NMR, resonance Raman, and X-ray absorption spectroscopy. The combined spectroscopic results indicate that the manganese(V)-oxo porphyrins are diamagnetic low-spin (S = 0) species with a longer, weaker Mn-O bond than in previously reported Mn(V)-oxo complexes of non-porphyrin ligands. This is indicative of double-bond character between the manganese(V) ion and the oxygen atom and may be attributed to the presence of a trans axial ligand. The [(Porp)Mn(V)=O](+) species are stable in the presence of base at room temperature. The stability of the intermediates is dependent on base concentration. In the absence of base, (Porp)Mn(IV)=O is generated instead of the [(Porp)Mn(V)=O](+) species. The stability of the [(Porp)Mn(V)=O](+) species also depends on the electronic nature of the porphyrin ligands: [(Porp)Mn(V)=O](+) complexes bearing electron-deficient porphyrin ligands are more stable than those bearing electron-rich porphyrins. Reactivity studies of manganese(V)-oxo porphyrins revealed that the intermediates are capable of oxygenating PPh(3) and thioanisoles, but not olefins and alkanes at room temperature. These results indicate that the oxidizing power of [(Porp)Mn(V)=O](+) is low in the presence of base. However, when the [(Porp)Mn(V)=O](+) complexes were associated with iodosylbenzene in the presence of olefins and alkanes, high yields of oxygenated products were obtained in the catalytic olefin epoxidation and alkane hydroxylation reactions. Mechanistic aspects, such as oxygen exchange between [(Porp)Mn(V)=16O](+) and H(2)(18)O, are also discussed.     

Phase diagram of electrostricted H2O at surfaces of electrodes at 273-373 K: electric critical point of water.

The equation of state of an open system containing water in an electric field of strength E greater than 108 V m-1 leads to a phase diagram with two-phase and single-phase regions in the Pi,E,T coordinates (=electrostriction pressure). The phases differ by their degree of orientation of H2O molecules in the field. The phase transition is discontinuous with respect to E. The calculation shows that the discontinuity vanishes at the critical point: Pi(c) approximately 0.2 GPa, Ec approximately 109 V m-1 and below 313 K. The thermal effect of the transition is calculated and compared with an experiment at the Hg/aqueous electrolyte interface found in the literature.     

在批次和固定床反应器中用于菜子油酯化K/Al_2O_3催化剂的稳定性(英文)

Catalytically active, stable, and mechanically durable solid K/Al2O3 catalysts for the transesterifica-tion of rapeseed oil with methanol was studied. In a batch reactor, high catalytic activity was accompanied by leaching of K species, caused by glycerol, and mechanical destruction of the solid catalyst as a result of contact with the stirrer. In a fixed-bed reactor, some leaching of K species into the liquid phases was also observed, but approached 0 during 30 h of time-on-stream; the activity of the K/Al2O3 catalyst(~83% ester yield) was stable for 100 h of time-on-stream and no mechanical destruction of the catalyst was observed. The populations of K2O and K-O-Al species for fresh and used K/Al2O3 catalysts were compared using Fourier transform infrared spectroscopy. It was found that some K2O species leached into the liquid phases at the beginning of the reaction.     

Raman investigation of the n(2)-o(2) binary system as a function of pressure and temperature

We produced mixtures of N2-O2 with different concentrations and performed low-temperature Raman studies at ambient and high pressures. From spectra in vibron and phonon regions, we determined band frequency, bandwidth, and band intensity as a function of temperature, pressure, and concentration. We determined the vibron Raman cross-sections and deduced the true concentrations of mixtures from vibron Raman band intensities. These concentrations were different from those determined from partial gas pressure of the initial gaseous mixtures. From fingerprints in Raman spectra, such as jumps in band frequencies or additional band splitting, we were able to prove phase transitions and propose a preliminary T-x phase diagram. We compared this diagram with two reported in the literature from structural analysis. Comparing all three variants of the T-x phase diagrams we found several discrepancies and inconsistencies, which we associate with different solid sample production techniques. Since we could prove that our samples were in thermodynamic equilibrium, we are convinced that we improved the known phase diagram substantially. From Raman band intensities of the O2 vibrations in different phases of N2 and O2, we were able to determine quantitatively the solubility of O2 in N2. Preliminary Raman studies of 2% and 7% O2 in N2 at high pressure and low temperatures showed that a larger amount of O2 can be dissolved in N2 than at ambient pressure. At the critical pressure (p approximately 15 GPa) we found from Raman spectra that O2 is demixed from 7% O2 in N2 to form epsilon-O2. This was previously called a "new phase" in the literature and not understood up to now. Finally, from band frequencies we determined the environmental shift of oxygen molecules in the mixture which is related to the intermolecular potential U(N2-O2) between different types of molecules.