Precise Conductance Measurements on Dilute Aqueous Solutions of Sodium and Potassium Hydrogenphosphate and Dihydrogenphosphate

Precise conductance measurements are reported on dilute aqueous solutions of the sodium and potassium salts of orthophosphoric acid at 25 ^∘C. Conductance measurements on solutions of electrolytes such as these phosphate salts that exist in solution as complicated mixtures of ions have previously proved difficult to interpret. To overcome this, a mathematical method has been developed to calculate the concentrations of all the species in the aqueous system M₃PO₄/M₂HPO₄/M₂HPO₄/H₃PO₄ (M = Na or K) over a continuous range of stoichiometries. The Lee–Wheaton conductance equation has been used to interpret the conductance of these multicomponent solutions in terms of the limiting ionic conductances and concentrations of all the ions in the solution. The limiting molar conductances of the ions H₂PO₄ ⁻ and HPO₄ ²⁻ and the ion-pair formation constants of these ions with sodium and potassium ions were determine This work has enabled the accurate determination of solution parameters for the important hydrogenphosphate ions in water and provides an excellent example of the use of an advanced conductance theory in the analysis of the conductance of multicomponent electrolyte systems.     

Conductance theory of concentrated electrolytes in an MSA-type approximation

A closed system of equations for the nonequilibrium pair-distribution function is given which corresponds to the mean spherical approximation (MSA) in equilibrium. The electrophoretic contribution to the conductance is calculated exactly in the framework of the MSA. For the calculation of the remaining contributions the equilibrium distribution function due to Henderson and Smith was used. The final expressions for the conductance are given in analytic terms using the restricted primitive model. The calculated curves are in good agreement with experimental data for 1-1 electrolytes up to about 1 M and qualitatively show the right behaviour up to rather high concentrations.     

Conductance and Thermodynamic Study of the Complexation of Ammonium Ion with Different Crown Ethers in Binary Nonaqueous Solvents

A conductance study of the interaction between ammonium ion and 18‐Crown‐6 (18C6), dicyclohexano‐18‐crown‐6 (DC18C6), ditertbutyl‐dicyclohexano‐18‐crown‐6 (t‐bu)₂DC18C6, diaza‐15‐crown‐5 (DA15C5), dibenzo‐21‐crown‐7 (DB21C7) and N‐Phenylaza‐15‐crown‐5 (NPA15C5) in acetonitril‐di‐methylsulfoxide mixture was carried out at various temperatures. The formation constants of the resultant 1:1 complexes were determined from the molar conductance‐mole ratio data and found to vary in the order of DA15C5 > DC18C6 > 18C6 > (t‐bu)₂DC18C6 > DB21C7 > NPA15C5. The enthalpy and entropy of the complexation reactions were determined from the temperature dependence of the formation constants.     

Conductance equation of dilute mixed strong electrolytes. III. Electrophoresis

The electrophoretic velocity is computed through the order linear in concentration for a system containing any number of species of ions of any charges. The computation is based on the general theory of Fuoss and Onsager and the method for the generalization to mixed electrolytes developed by Chen and Onsager for the primitive model. The Boltzmann factor exp. (—e_{i ji}/kT) is retained explicitly through the computation to obtain a result consistent with earlier computations of the relaxation field. The equilibrium potential including a correction to Poisson-Boltzmann equation is used, which adds a linear term V _j ^c to the electrophoretic velocity in agreement with the result of Murphy and Cohen. The correction to the ionic distribution due to the solvent motion is considered, which results in a linear term inversely proportional to the square of the viscosity of the solution. The main contribution is V _j ^E , which is in agreement with the result for symmetrical electrolytes of Falkenhagen et al. with only a slight difference due mainly to the different approximation used in the computation of the local force.     

二甲基甲酰胺-二氧六环混合溶剂中KBr,KSCN及KClO_4的电导研究

本文报告了KBr、KSC N、KClO_4和KI在二甲基甲酰胺(DMF)和1,4-二氧六环混合溶剂中的电导测定值、溶剂的粘度和溶液的密度,按Pitts,Fuoss1978和Lee-Wheaton电导方程拟合实验数据得出溶液的无限稀释摩尔电导A_o,离子缔合常数K_α和正负离子间的距离参数R。对三个方程的适用性和溶液中离子-离子-溶剂分子间的相互作用作了初步讨论。     

Prediction of the Conductance of Strong Electrolytes and the Calculation of the Ionization Constant of Weak Electrolytes in a Dilute Solution by a New Equation

In order to predict the conductance for dilute 1-1 valent electrolyte solutions,a new conductance equation was proposed based on the Onsager and Onsagar-Fuoss-Chen conductance equation.It has only one parameter A,which can be obtained directly from the data of ionic limiting molar conductivity Λ∞m,and its expression is very simple.The new equation has been verified by the experimental molar conductivities of some single strong electrolyte and mixed electrolyte solutions at 298.15 K reported in literatures.The results are in good agreement with the experimental data.Meanwhile the ionization constants of some weak electrolyte solutions were calculated by a modified equation of this new equation,and it was also found that the calculation results are in good agreement with the data in the literature.     

用于锂离子电池的凝胶聚合物电解质的制备与性能

以丙烯腈(AN)、丙烯酸甲酯(MA)和衣康酸锂(IALi)为自由基共聚反应的主要单体, 采用溶液聚合方法, 合成轻度交联的P(AN-MA-IALi)聚合物电解质膜.通过FTIR, DSC和SEM等测试方法对共聚物的结构进行了表征, 利用交流阻抗等电化学方法对该膜的导电性能进行了研究.实验结果表明, 所制备的交联聚合物的室温电导率达到10-5~10-4 S/cm, 当IALi的质量分数为3%时, 所制备的聚合物电解质膜的电导率最大可达到1.89×10-4 S/cm.     

Interactions in water-alcohol mixtures: Conductance of lithium picrate in solutions of water and isomeric pentanols at 25°C

Conductance measurements of lithium picrate in solutions of water in n-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol and 3-methyl-1-butanol have been carried out at 25°C. Ionic association and conductance were found to change with water content and with the molecular structure of the alcohols (i.e. position of the OH group and degree of branching of the alkyl chain). These results indicate that both conductance and ion pair formation are not the consequence of the simple motion of ions in the electrical field as required by the continuum model. A more realistic approach, involving the internal structure of the solvent mixtures, has been considered.     

高效毛细管电泳电导检测对阴离子表面活性剂分离测定的研究

以Ca2 +为分离介质 ,甲酰胺为添加剂 ,通过对缓冲体系、缓冲液浓度、酸度、Ca2 +浓度、甲酰胺浓度、电泳电压和进样时间的优化选择 ,用毛细管电泳 -电导检测法分离了十二烷基硫酸钠(K12)和十二烷基苯磺酸钠(LAS) ;在10mmol/LTris -11mmol/LCit(pH4.5)运行缓冲液中 ,上述两组分在16min内完全分离 ;K12和LAS的线性范围分别为5.0×10-6～8.0×10-3 mol/L和5.0×10-6 ～5.0×10-3 mol/L ;检出限(S/N=3)分别为2.5×10-6 和3.0×10-6 mol/L,应用于合成洗衣粉样和合成水样中K12 和LAS测定 ,结果令人满意。     

Ion channels of biological membranes: prediction of single channel conductance

The Poisson-Boltzmann equation was solved numerically for models of the pore regions of the Shaker K⁺ channel and of two glycoporins (LamB and ScrY) to yield electrostatic potential profiles along the pore axes. From these potential profiles, single-channel current-voltage (I–V) relations were calculated. The importance of a proper treatment of the ionisation state of two rings of aspartate sidechains at the mouth of the K⁺ channel pore emerged from such calculations. The calculated most likely state, in which only two of the eight aspartate sidechains were deprotonated, yielded better agreement with experimental conductance data. An approximate calculation of single-channel conductances based simply on pore geometry yielded very similar conductance values for the two glycoporins. This differed from an␣experimentally determined conductance ratio of ScrY:LamB=10:1. Preliminary electrostatics calculations appeared to reproduce the observed difference in conductance between the two glycoporins, confirming that single-channel conductance is determined by electrostatic as well as geometric considerations. Received: 25 May 1998 / Accepted: 4 August 1998 / Published online: 2 November 1998     

电导法研究过饱和铝酸钠溶液均相成核过程

采用自行研制电导在线跟踪仪, 配套特制的传感器式电导电极, 研究铝酸钠溶液均相成核过程中溶液电导变化规律, 及溶液过饱和度对反应诱导期作用; 通过测定铝酸钠溶液均相成核过程诱导期, 结合溶液均相成核理论, 测得323 K下, 饱和度S>3.8的铝酸钠溶液均相成核过程中的表观反应级数n=4±1, 固-液界面能γ=(40.6±2.0) mJ·m-2, 并据此估算临界成核粒径rc=(1.1±0.2) nm. 研究结果与文献值吻合, 证明该套仪器具有较高的灵敏度和可靠性.     

Studies on the Anode/Electrolyte Interfacein Lithium Ion Batteries

Summary.  Rechargeable lithium ion cells operate at voltages of 3.5–4.5 V, which is far beyond the thermodynamic stability window of the battery electrolyte. Strong electrolyte reduction and anode corrosion has to be anticipated, leading to irreversible loss of electroactive material and electrolyte and thus strongly deteriorating cell performance. To minimize these reactions, anode and electrolyte components have to be combined that induce the electrolyte reduction products to form an effectively protecting film at the anode/electrolyte interface, which hinders further electrolyte decomposition reactions, but acts as membrane for the lithium cations, i.e. behaving as a solid electrolyte interphase (SEI). This paper focuses on important aspects of the SEI. By using key examples, the effects of film forming electrolyte additives and the change of the active anode material from carbons to lithium storage alloys are highlighted. Received May 30, 2000. Accepted June 14, 2000     

康普顿散射法测定溶液浓度

基于光子与物质相互作用的康普顿散射效应,利用康普顿散射光子数与散射体的电子密度成正比的原理,提出了用康普顿散射测定溶液浓度的方法,描述了相应的试验装置和测定溶液浓度的步骤,并用此方法测定了氢氧化钠和氯化钾溶液的浓度,分析了引起误差的原因。试验结果表明,用所提出的方法测定溶液的浓度是可行的。     

纳滤膜对电解质溶液分离特性的理论研究(I): 单一电解质溶液

电解质溶液在纳滤膜中的截留率对于膜法海水淡化和重金属离子的脱除非常重要. 本文假定膜具有狭缝状孔, 采用扩展Nernst-Planck方程、Donnan平衡模型和Gouy-Chapman理论来描述电解质溶液中离子在膜孔内的传递现象. 使用纯水透过系数、膜孔径及膜表面电势来表征纳滤膜的分离特征, 这三个参数可通过Levenberg-Marquardt方法由实验数据关联得到. 本文使用该模型计算了两种商用纳滤膜(NF45和SU200)对1-1型(NaCl, KCl, LiCl), 2-1型(K₂SO₄)和2-2型(MgSO₄)单一电解质溶液的截留率, 并与实验数据进行了比较, 两者吻合较好. 计算结果表明电解质溶液中离子在纳滤膜孔内传递的主要机理是离子的扩散和电迁移, 纳滤膜对电解质溶液中离子的分离效果主要由空间位阻和静电效应决定. 该模型在低浓度时对电解质溶液通过纳滤膜的截留率计算结果较准确, 但对高浓度电解质溶液则偏差较大.     

Conductance of 1:1 electrolytes in methyl formate

The electrolytic conductivities of LiClO₄, LiAlCl₄, LiAsF₆, NaClO₄, NaBPh₄, and Bu₄NClO₄ have been measured in methyl formate at 25°C. Evidence is presented for strong association between the perchlorate ion and the formyl proton of the solvent. Ion association and triple ion formation constants suggest that LiClO₄, LiAlCl₄, and NaClO₄ form solvent separate ion pairs and triple ions. NaBPh₄ forms contact ion pairs and triple ions, and the remaining salts appear to form both types of ion pairs and triple ions.     

纳滤膜对电解质溶液分离特性的理论研究(II): 混合电解质溶液

假定纳滤膜具有狭缝状孔, 使用纯水透过系数、膜孔径及膜表面电势来表征纳滤膜的分离特征, 用流体力学半径和无限稀释扩散系数表征了离子特性. 采用扩展Nernst-Planck方程、Donnan平衡模型和Poisson-Boltzmann理论描述了混合电解质溶液中离子在膜孔内的传递现象, 计算了三种商用纳滤膜(ESNA1-LF, ESNA1和LES90)对同阴离子、同阳离子和含四种离子的混合电解质体系中离子的截留率, 并与实验数据进行了比较. 计算结果表明, 电解质溶液中离子在纳滤膜孔内传递的主要机理是离子的扩散和电迁移, 纳滤膜对混合电解质溶液中离子的分离效果主要由空间位阻和静电效应决定. 该模型在低浓度时对含一价离子的混合电解质溶液通过纳滤膜的截留率计算结果比较准确, 但对高浓度或含高价离子的混合电解质溶液则偏差较大.     

A Kinetic Model of Metal Ion Electrodeposition from Solutions of PPM and PPB Concentrations

Abstract

A mathematical, kinetic model is presented for the electro-deposition of heavy metal ions present in solutions in ppm and ppb concentrations. The model is based on the two main assumptins: of metal monolayer formation, and of simultaneous metal deposition and dissolution.     

The Analysis of Galvanizing Preflux Solutions for Zinc by Flow Injection-Flame Atomic Absorption Spectrometry

Abstract

A direct flow injection flame atomic absorption spectrometry method of determining zinc salt solutions with concentrations of 100's g dm^?3 is reported. It was shown that high concentrations of KCl, NaCl and NH₄Cl do not significantly interfere with the determination of zinc in both the mg dm^?3 and g dm^?3 concentration ranges. Where g dm^?3 concentrations were determined a secondary spectral line at 307.6 nm was found satisfactory. Galvanizing preflux solutions were analyzed both after dilution to the mg dm^?3 range at 213.9 nm and directly injected at 307.6 nm. Precisions of better than 6.6% rsd were observed by the direct method compared with better than 4.8 by dilution techniques. Concentrations up to 110 g dm^?3 in zinc were determined the total salt content being greater than 300 g dm^?3.