共查询到20条相似文献,搜索用时 46 毫秒
1.
The ion product of water and the dissociation constants of carbonic acid have been determined in 0.1, 1.0, 3.0, and 5.0M NaClO4 at 25°C. The ion product of water K
w
'
has been evaluated by emf measurements with a combined glass electrode in NaClO4 solutions containing 0.001–0.1M HCLO4 or NaOH. The product K
H
'
K
l
'
K
2
'
of the Henry constant for CO2 and the dissociation constants for H2CO3 have been determined by titration of carbonate solutions equilibrated with pCO2 =10–3.52 atm, and K
2
'
has been evaluated by potentiometric titration and by measuring the H+ concentration at fixed HCO
3
–
and CO
3
2-
concentrations. The ion interaction (Pitzer) equations are applied to describe the constants K
w
'
, K
2
'
and K
H
'
H
1
'
K
2
'
as a function of the NaClO4 concentration. The experimental data are used to evaluate the mixing parameters
i/ClO
4 and
i/ClO
4
-/Na+ fori = OH
-,HCO
3
-
andCO
3
2- 相似文献
2.
《Electrochemistry communications》2000,2(7):480-486
The properties of poly(3,4-ethylenedioxythiophene) (PEDT) film have been studied in iodide solutions by cyclic voltammetry and stripping voltammetry methods. It has been shown that formation of charge-transfer complexes between iodine species and polymeric rings promotes storage of iodine on an electrode covered by PEDT film. Due to this behaviour the PEDT layer can be employed for electroanalysis of dilute (10−4–10−3 M) solutions of iodide salts by stripping voltammetry methods. The possibility of PEDT film application for zinc-iodide rechargeable batteries was also examined. 相似文献
3.
This paper reports on the preparation of SO4 2?/Fe2O3–TiO2–Nd2O3 (SFTN) by combustion method. The effect of Nd content on catalytic activity was investigated. The prepared materials doped and undoped by Nd were compared by means of TG-DTG, XRD, FT-IR, NH3-TPD and TEM techniques. Results indicated that the introduction of Nd improved the catalytic activities of the catalysts. Catalytic activity of SFTN was the highest with 98.3 % menthol conversion when Nd content was at 2 wt%. The introduction of Nd stabilized the coordination bond between the sulfate irons and the metallic oxides, helping in the formation of solid acid sites, enhancing the dispersion of catalyst particles, and inhibiting the growth of catalyst particles under heating. 相似文献
4.
Research on Chemical Intermediates - The effect of Pd content on the performance of the Pd-S2O8 2?/ZrO2-Al2O3 solid superacid catalyst was studied using n-pentane isomerization as a probe... 相似文献
5.
B. Hu 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(5):777-779
The Pitzer ion-interaction extended by Harvic and Weare was applied to predict the solubility isotherms of reciprocal quaternary systems in which mixed crystals are formed. On the basis of data concerning the binary and ternary subsystems, the four components systems Rb+, Cs+/Cl?, SO 4 2? -H2O, and K+, Cs+/Cl?, SO 4 2? -H2O were investigated at 25°C.The results of calculation can be used to model salt crystallization during the concentration of brines. 相似文献
6.
运用M062X和X3LYP两种密度泛函理论(DFT)方法在TZVP和6-311++G(2d,p)+LANL2DZ基组水平上,对已报道的15种脯氨酸(Pro)构象分别与Zn2+、Zn+及Zn进行不同方式配位体系的几何结构、能量学特征、振动光谱和电子结构性质进行了计算研究.Pro-Zn2+、Pro-Zn+和Pro-Zn三种体系分别得到19、21和24种稳定结构.Pro-Zn2+体系中Zn2+与Pro两性离子的氧端(OO)配位形成的四元环结构能量最低,其次是与Pro羧羰基氧和亚氨基氮配位形成的五元环结构,而Pro-Zn+体系与之相反.Pro-Zn2+/1+/0体系的相对能差逐渐降低,结合能分别位于-620--936,-139--325和-1.5--22 kJ·mol-1范围,配位Pro的变形能随价态降低而减小.ProZn2+体系受方法和基组影响较大,离子体系中Zn均获得少量负电荷,所有配位化合物的前线轨道能差均比相应两个碎片要低. 相似文献
7.
《Bioelectrochemistry and bioenergetics (Lausanne, Switzerland)》1998,44(2):285-288
The effect of Ca2+ on the electron transfer of Fe(CN)63−/4− couple at Pt supported lecithin (PC)/cholesterol (CH) bilayer lipid membrane (BLM) electrode has been studied by voltammetry and ac impedance spectroscopy. Experimental results suggest that the interaction of Ca2+ with the BLM can open some kind of channel for Fe(CN)63−/4− ions, allowing increased access of the redox couple to the electrode surface. This phenomenon may be related to the Ca2+ regulation or activation effect of ion channel in some biomembranes. 相似文献
8.
9.
以三聚氰胺和氯铂酸(H2PtCl6·6H2O)为原材料,采用简单一步煅烧法制备了不同含量的Pt^2+/Pt^0掺杂石墨相氮化碳(Pt^2+/Pt^0-CN)。运用扫描电镜、透射电子显微镜、X射线光电子能谱、X射线粉末衍射、N2物理吸附-脱附、紫外-可见漫反射光谱和光电流测试等技术对制备的样品的形貌、化学组成、晶体结构、比表面积和光电性能等物理化学性质进行了表征。由XPS可知Pt粒子以二价Pt和零价Pt掺杂在催化剂的表面和内部,其中Pt^0与Pt^2+的比约为1∶7.26。与g-C3N4相比,Pt^2+/Pt^0-CN表现出高效的光催化降解活性。当Pt^2+/Pt^0理论负载质量分数为0.02%时,对环丙沙星、罗丹明B、酸性橙Ⅱ、甲基橙和亚甲基蓝的降解效率分别提升了43%、64%、39%、42%和52%。Pt^2+/Pt0掺杂使催化剂的比表面积大幅度增加,同时增强光催化剂对光的吸收能力,并抑制光生电子(e^-)和空穴(h^+)的复合。 相似文献
10.
Fe3+/V5+/TiO2复合纳米微粒光催化性能的研究 总被引:29,自引:1,他引:29
采用溶胶凝胶法制备了Fe^3 /V^5 /TiO2复合纳米微粒作为光催化剂。光降解反应结果表明,其掺杂催化剂Fe^3 /V^5 /TiO2的光催化活性明显提高。光电化学研究显示,铁离子可以成为电荷陷阱,促进空穴的界面传递反应。适量钒离子掺杂使TiO2电极的光电流升高,导带中电子浓度的增大,加快了界面的电子传递反应。共掺杂催化剂中,Fe^3 、V^5 分别提供了空穴与电子的陷阱,同时加快了电子与空穴的界面传递反应,从 更有效地提高光催化活性。双组份共掺杂为提高TiO2光催化活性提供新的途径。 相似文献
11.
《Solid State Sciences》2000,2(4):495-500
The polythermal diagram of the ternary system H2ONa2HPO4Na2SO4 has been established, setting up nine isotherms obtained between 0 and 25°C by conductimetric analysis. The solubility domains of the various solid phases have been determined. One eutectic, three stable and one metastable transitional transformations have been observed. Temperature and composition of the eutectic point have been obtained by thermal analysis at constant flow. 相似文献
12.
Todora Ojkova Donka Stoilova Dimitar Barkov 《Monatshefte für Chemie / Chemical Monthly》2000,131(10):1019-1023
Summary. The solubilities in the systems Rb2SeO4=ZnSeO4=H2O and Cs2SeO4=ZnSeO4=H2O at 25°C were studied by the method of isothermal decrease of supersaturation. Comparatively wide crystallization fields
of the double salts Rb2Zn(SeO4)2ċ6H2O and Cs2Zn(SeO4)2ċ6H2O are observed in the solubility diagrams. The double salts form monoclinic crystals which are isostructural with those of
the corresponding rubidium and cesium zinc sulfate hexahydrates. TG and TDA measurements indicate that the double salts lose
their crystallization water in one step in the temperature intervals of 50–160°C (rubidium salt) and 70–150°C (cesium salt).
Received March 14, 2000. Accepted (revised) June 5, 2000 相似文献
13.
Equilibrium solubility curves of the ammonium aluminium sulphate in aqueous solutions of sulphuric acid have been calculated
using checked literature data and our own measurements. The concentration of sulphuric acid ranged from 0 to 23 mass%, temperature
range between 20 and 60°C has been extrapolated up to 75°C by means of a thermodynamically based correlation method. The solubility
correlation as well as the hydration analysis implied a possible destructuralization of solutions at higher acid concentrations.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
14.
15.
16.
V. L. Lobachev 《Theoretical and Experimental Chemistry》1999,35(1):40-44
The substrate selectivity in the hydroxylation of methylbenzenes in the H2O2−H2SO4 (70 wt.%) system was studied at 15–55 °C. The activation entropy correlates with the basicity of the arenes, while the substrate
selectivity and activation enthalpy correspond both with the basicity and ionization potentials of ArH. We concluded that
the structure of the reaction transition state is intermediate between a charge transfer complex and σ-complex.
L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 R. Lyuksemburg
ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 35, No. 1, pp. 39–43, January–February,
1999. 相似文献
17.
Djerdj I Škapin SD Ceh M Jagličić Z Pajić D Kozlevčar B Orel B Orel ZC 《Dalton transactions (Cambridge, England : 2003)》2012,41(2):581-589
The title compound has been synthesized under solvothermal conditions by reacting vanadium(V) oxytriisopropoxide with terephthalic acid in N,N-dimethylformamide. A combination of synchrotron powder diffraction, infrared spectroscopy, scanning and transmission electron microscopy, and thermal and chemical analysis elucidated the chemical, structural and microstructural features of a new 2D layered inorganic-organic framework. Due to the low-crystallinity of the final material, its crystal structure has been solved from synchrotron X-ray powder diffraction data using a direct space global optimization technique and subsequent constraint Rietveld refinement. [V(4)O(4)(OH)(2)(O(2)CC(6)H(4)CO(2))(4)]·DMF crystallizes in the monoclinic system (space group P2/m (No. 10)); cell parameters: a = 20.923(4) ?, b = 5.963(4) ?, c = 20.425(1) ?, β = 123.70(6)°, V = 2120.1(9) ?(3), Z = 2. The overall structure can be described as an array of parallel 2D layers running along [-101] direction, consisting of two types of vanadium oxidation states and coordination polyhedra: face-shared trigonal prisms (V(4+)) and distorted corner-shared square pyramids (V(5+)). Both configurations form independent parallel chains oriented along the 2-fold symmetry crystallographic b-axis mutually interlinked with terephthalate ligands in a monodentate mode perpendicular to it. The morphology of the compound exhibits long nanofibers, with the growth direction along the layered [-101] axis. The magnetic susceptibility measurements show that the magnetic properties of [V(4)O(4)(OH)(2)(O(2)CC(6)H(4)CO(2))(4)]·DMF can be described by a linear antiferromagnetic chain model, with the isotropic exchange interaction of J = -75 K between the nearest V(4+) neighbours of S = 1/2. 相似文献
18.
为了实现生产低硫柴油和超低硫柴油的目标,以超声波为外加能源,构筑超声波/类Fenton试剂的柴油氧化脱硫反应体系,考察了水相pH值和超声功率这两个参数对柴油氧化脱硫效果的影响。实验结果表明,当类Fenton试剂的水相pH值为2.00左右时,其脱硫效果较好;无超声波下H2O2、类Fenton试剂、超声波/H2O2及超声波/类Fenton试剂的柴油氧化脱硫反应符合表观一级反应动力学规律。超声波功率的提高对氧化脱硫有明显的促进作用,这主要是由于功率的增加,有助于加速空穴的形成与内爆,从而促进反应的进行。 相似文献
19.
采用荧光光谱、紫外-可见光谱技术研究了芦丁与牛血清白蛋白(BSA)在金属离子Cu2+/CO2+共存时的相互作用.研究结果表明:有或无金属离子存在时,芦丁对BSA的荧光猝灭作用都是由于生成复合物而引起的静态猝灭;金属离子的存在使芦丁与BSA的表观结合常数KLB增大,且Co使KL)增大得更明显.由热力学参数确定芦丁和BSA... 相似文献
20.
Cu2+/TiO2对甲基橙的光催化降解机理 总被引:11,自引:1,他引:10
以自制的掺铜离子的混晶型二氧化钛为光催化剂,考察了甲基橙光催化降解过程中pH值和光源的影响,提出了两种不同的光催化降解机理:在高压汞灯照射下,TiO2的价带电子被激发到导带,光生电子和空穴主要通过Cu2+ 的短路循环而复合,光催化剂的活性降低;在太阳光照射下,甲基橙发生自身光敏化氧化反应,受激电子从单线态或三线态的甲基橙分子跃迁到TiO2的导带,Cu2+起到电荷传递中继站的作用,加速了注入电子向H2O2的转移,从而促进了甲基橙的光催化降解。 相似文献