Mass Transfer Rate through Liquid Membranes: Interfacial Chemical Reactions and Diffusion as Simultaneous Permeability Controlling Factors

Abstract

Equations describing the permeability of a liquid membrane to metal cations have been derived taking into account aqueous diffusion, membrane diffusion, and interfacial chemical reactions as simultaneous permeability controlling factors. Diffusion and chemical reactions have been coupled by a simple model analogous to the one previously described by us to represent liquid-liquid extraction kinetics. The derived equations, which make use of experimentally determined interfacial reaction mechanisms, qualitatively fit unexplained literature data regarding Cu²⁺ transfer through liquid membranes. Their use to predict and optimize membrane permeability in practical separation processes by setting the appropriate concentration of the membrane carrier [LIX 64 (General Mills), a commercial β-hydroxy-oxime] and the pH of the aqueous copper feed solution is briefly discussed.     

乳状液膜分离Zn^2＋的界面传质阻力及传质模型

用Ｌｗｅｉｓ恒界面传质池对乳状液膜分离Ｚｎ＾２＋的传质阻力进行实验研究，结果表明由于表面活性剂单分子层的形成，使界面传质阻力占整个传质阻力的８５％。在此基础上所建立的既考虑界面传质阻力又考虑膜破碎的液膜传质模型能使用理论计算值与实验测定值符合较好。     

Interfacial Mass Transfer in Ligand Accelerated Metal Extraction by Liquid Surfactant Membranes

Abstract

Interfacial mass transfer rates were determined for the extraction of Co(II), Ni(II), and Cu(II) by di-(2-ethyl hexyl) phosphoric acid by using a modified Lewis cell. This allowed us to elucidate the effect of ligands on liquid surfactant membrane extraction of heavy metal ions by ligand addition to the external aqueous phase. The effects of different ligands on the kinetics of extraction and the influence of surfactant on interfacial resistance to mass transfer were then examined.     

Solvent Extraction Behavior of Trivalent Metals with Liquid Ion Exchangers

Abstract

A systematic liquid-liquid extraction behavior of some trivalent metals has been carried out with the high-molecular-weight synthetic carboxylie acid SRS-100 with benzene as diluent. In most cases extraction was quantitative; but in the casss of gallium and antimony the maximum extraction was 97.2 and 65%, respectively. Using pure solvent (without benzene diluent), quantitative extraction (> 99%) of gallium was possible with SRS-100 at pH 4.6. Gradual neutralization techniques have been adopted to study the extraction behavior of antimony in the pH range 2.0–6.5. The effect of metal ion concentration, solvent concentration, salting-out agents, diluents, and finally the interferences of associated elements were critically examined. The percentage extraction at various ranges of pH has also been studied. Some important separations have been carried out by exchange reactions. The proposed methods are very simple, rapid, and fairly selective. They can be carried out both at micro and macro levels.     

Countercurrent Extraction. Mass Transfer Kinetics and Time-Dependent Behavior

Abstract

The time-dependent behavior of countercurrent extraction columns is modeled mathematically. The effects of aqueous and organic phase flow rates, number of theoretical plates, mass transfer kinetics, and pulse influent concentration overloads are determined. Use of an asymmetrical upwind algorithm to model advection allows substantial reductions in the computer time required. The effluent organic phase approaches its steady-state concentration much more rapidly than does the effluent aqueous phase.     

Interfacial Mass Transfer in the Reactive Extraction Process of Succinic Acid from Viscous Aqueous Solutions

The reactive extraction of succinic acid with TOA dissolved in butyl acetate from viscous aqueous solutions which simulate the rheological behavior of Actinobacillus succinogenes broths underlined the strong influence of viscosity and pH on interfacial mass flow, mass transfer driving force, and mass transfer coefficient. The magnitudes of these effects are attenuated by 1-octanol addition into the solvent phase, the interfacial mass transfer rate being accelerated for 1.2-3 times, depending on the apparent viscosity and the pH-value of the aqueous solution. The influences of the extraction parameters and mechanism have been included in a mathematical model adequate for the solute mass transfer coefficient from aqueous to organic phase.     

气液传质过程的界面湍动

界面湍动对相际传质具有重要影响。利用显微激光全息干涉技术研究了 CO2 在乙醇 -水溶液中吸收过程的界面湍动情况 ,实验观察了界面湍动强度与溶液浓度的关系 ,结果表明 ,乙醇浓度越高 ,界面湍动强度越大 ,文中对此进行了分析和讨论。     

乳化液膜传质动力学模型的研究进展

本文综述了乳化液膜传质动力学模型的发展状况：从最简化的平板模型,空心球模型到较为详尽的渐进前沿模型乃至其他传质模型;对各传质动力学模型的优缺点进行了比较和评价,指出了不同模型的应用范围。在此基础上,介绍了改进的渐进前沿模型;同时,对传质动力学模型今后的发展方向进行了预测。     

Separation of Osmium(VIII) from Platinum Group Metals by Extraction with Liquid Ion Exchangers

Abstract

A method is developed for the extraction and separation of osmium from palladium, platinum, ruthenium, rhodium, and iridium with tri-n-octyl amine either from hydrochloric or hydrobromic acid solutions. The extracted species is (R₃NH⁺)₂OsCl₆ ^2-. The method is shown to be applicable to synthetic mixtures.     

Interfacial Behavior of Cyanex 272 and Mass Transfer Kinetics of Ytterbium Using the Constant Interfacial Area Cell

The interfacial behavior of Cyanex 272 has been investigated using the Du Nouy ring method. Different adsorption isotherms such as the Gibbs and Szyszkowski isotherms have been found as fitting well to the experimental data. The values of interfacial excess at the saturated interface increase in the following order: n-heptane > cyclohexane > CCl₄ > toluene > benzene > chloroform, explained according to the stronger solution effect of aromatic hydrocarbon. The effects of temperature, acidity, and ionic strength of the aqueous phase on the interfacial activity of Cyanex 272 are also examined and explained in detail. Moreover, the reaction orders against Cyanex 272 predicted from the interfacial tension isotherms are in agreement with the order determined experimentally, which suggests that the interfacial activity of Cyanex 272 can provide enough strong evidence quantitatively supporting the interfacial mechanism.     

Overall Rate Analysis of the Gaseous Reduction of Stable Oxides Incorporating Chemical Kinetics, Mass Transfer, and Chemical Equilibrium

A unified mathematical relationship for the overall rate of gaseous reduction of a stable oxide that produces a volatile suboxide has been derived including the effects of a product gas in the bulk stream, chemical kinetics, mass transfer, and chemical equilibrium. The important effect of the small equilibrium constant is quantified. How the reaction conditions affect the overall rate at different asymptotic conditions is also elucidated. By using the obtained results, the conflicting previous claims on the rate-controlling mechanism for the hydrogen reduction of silica has been critically examined and reconciled. The small equilibrium constant of this reaction causes it to be rate controlled by mass transfer under typical conditions and its rate to be slow. How the presence of even a small amount of water vapor in the bulk gas greatly enhances the effects of the small equilibrium constant is elucidated from the mathematical derivation. In addition, the small equilibrium constant also causes the apparent activation energy of silica reduction by wet hydrogen to approach the Δ H ° of reaction and that by dry hydrogen to approach     Δ H °. Because of the large positive Δ H ° value associated with reactions with a large positive Δ G ° value, such a reaction has been mistaken to be rate controlled by chemical kinetics.     

支撑液膜萃取乳酸传质模型

本文对使用支撑液膜(Supported Liquid Membrane)从水溶液中革取乳酸(HL)的过程进行了理论分析,经过适当的简化,推导出支撑液膜革取乳酸的传质模型。对模型进行了实验验证,测得了膜的弯曲因子及过程的促进因子,模型计算值与实验值相吻合,同时得出膜内载体三烷基氧磷(TRPO)与乳酸形成的萃合物分子式为HL·TRPO。     

Solvent Extraction Behavior of Cerium(IV), Zirconium,and Thorium with Liquid Ion Exchangers

Abstract

The systematic solvent extraction behavior of cerium(IV), zirconium, and thorium has been studied with the high molecular weight carboxylic acids SRS-100 and Versatic-9, with benzene as diluent. Quantitative extraction has been achieved in almost all cases. Only in the case of zirconium has incomplete extraction (73.5%) been reported with Versatic-9. Quantitative extraction requires three consecutive equilibrations at pH 2.9. The effect of metal ion concentration, solvent concentration, diluents, and the interference of the associated elements were critically examined. The percentage extraction at various ranges of pH has been studied. Exchange reaction techniques have been employed in several systems. The proposed methods are very simple, rapid, and fairly selective. They can be carried out both at micro and macro levels, and they are applicable to extraction of metal ions in the presence of other commonly interfering ions.     

湍球塔气液相界面结构及传质面积

湍球塔因其防堵塞、强湍动、传质面积大等特点,可作为烟气氨法脱碳后用磷石膏浆料净化尾气微量氨的气液传质设备。本文基于湍球塔液滴团聚分散理论研究了液滴和液膜形成的气液相界面结构,并得到气液传质面积的数学模型。在磷石膏浆料吸收氨法脱碳尾气微量氨的湍球塔实验装置中,在气体Re_g157~475、液气比1~6范围内进行实验研究,从实验数据回归得到的气液传质面积与理论计算值吻合。结果表明,湍球塔气液传质面积以团聚分散的液滴为主,湍球表面积占比不足25%。     

The Role of Mass Transfer in the Kinetics of Chemical Oxidation of Anthracine Slurry to Anthraquinone in a Batch Stirred Tank Reactor

The kinetics of chemical oxidation of anthracine powder by acidified dichromate in a batch agitated vessel stirred by a 45° four pitched blade turbine impeller was studied under different conditions. Variables studied were impeller rotation speed, solution physical properties and temperature. The rate of anthracine oxidation was found to increase with temperature according to the Arrhenius equation with an activation energy of 3.98 cal/mole. The rate of anthracine oxidation was found to increase with 0.56 power of impeller rotation speed. The value of the activation energy and the sensitivity of the rate of oxidation to stirring lend support to the diffusion‐controlled nature of the reaction. The data were correlated by the equation: Sh = 0.5 · 10^–3 Sc^0.33 · Fr^0.33 Implication of the above equation for the operation of industrial reactors was noted.     

纤维素酶法提取竹叶黄酮的传质动力学

采用纤维素酶法提取竹叶中的总黄酮类化合物,讨论了温度、原料尺寸、转速及纤维素酶用量对传质速率的影响,并用扫描电镜观察了水提和酶提取后样品的细胞结构变化。结果表明,竹叶黄酮的提取动力学符合平板型Fick第二定律,提取过程主要受内扩散控制;纤维素酶不改变传质动力学机理,它只破坏细胞壁,从而降低扩散阻力使溶质的传质速率和表观扩散系数D′提高。实验还得到了D′与提取温度、竹叶几何尺寸之间的关系,在30～60℃,酶提时的D′为1.95×10 13～6.85×10 13m2·s-1,水提时的D′为1.73×10 13～6.05×10 13m2·s-1;酶提时的活化能Ea为11.853kJ·mol-1,比水提时降低了9.59%。该研究为酶法提取竹叶黄酮的工艺设计及工业化应用提供了理论依据。     

Kinetics of Chemical Reactions During Detonation of Mixtures of Organic Substances with Nitric Acid

The kinetics and mechanism of chemical reactions in detonation waves propagating in mixtures of nitric acid with nitroglycol, ethylene glycol dinitrate, and acetic anhydride were studied within the framework of the Dremin—Trofimov theory of the detonation failure diameter. The state parameters in shock and detonation waves were calculated using the SGKR software package. It was shown that the decomposition of mixtures of nitric acid with organic substances in a detonation wave is a complex reaction which includes several stages. Various kinetic models are considered; effective values of the kinetic parameters are calculated for each model and for the entire process.     

支撑液膜法脱除氨氮的动力学

研究了以聚丙烯为支撑膜、以D2EHPA为载体脱除废水中的氨氮的支撑液膜体系。通过实验确定了料液pH值、载体浓度等与铵离子渗透系数之间的关系;建立了动力学方程。     

吸收过程的界面传质机理

Based on the method of molecular thermodynamics ,the mass transfer mechanism at gas-liquid interface is studied theoretically,and a nowe mathematical model is proposed,Using laser holographic interference technique,the hydrodynamics and mass transfer characteristics of CO2 absorption are measured,It is shown that the calculated results are in good agreement with the experimental data.