Interfacial Activity of Hydroxyoximes and mechanism and kinetics of palladium(II) extraction

Surface excess isothermers were determined and interpreted for systems containing 2-hydroxy-5-t-nonylbenzaldehyde oxime ( 1 ), 2-hydroxy-5-t-octylacetophenone oxime ( 2 ) and 2-hydroxy-5-t-octylbenzophenone oxime ( 3 ). These surface excess isotherms were used to predict reaction orders with respect to hydroxyoximes for various versions of interfacial process. Agreement with the experimental data was observed both for the interfacial and bulk aqueous mechanism. The surface activity of extractants cannot be recognized as the sole evidence for the interfacial mechanism of extraction. More experimental kinetic data are needed in order to determine the effect of hydroxyoxime concentration upon the reaction order. According to the interfacial mechanism, with the formation of the stable 2:1 complex as the limiting step the reaction order in hydroxyoxime equal to 1 is observed over a large range of hydroxyoxime concentration, but increases to 1.5-2.0 for very low concentrations.     

INTEKFACIAL ACTIVITY OF 2-HYDH0XY-5-ALKYLBEKZALDEHYDE OXIMES AHD MECHANISM AND KINETICS OF COPPER EXTRACTION

Different adsorption isotherms such as the Gibbs, Szyszkowski,Frumkln and Temkin and polynomial were found as fits well to experimental interfacial tension isotherms for 2-hydroxy-5-alkylbenzaldehyde oximes at octane/water and xylene/water interfaces. The values of surface excess computed according to them increase as the length of the alkyl chain length increases for xylene/water system. Different behaviour was found at octane/water interface.

The interfacial activity data were used to predict reaction orders against hydroxyoxime for different proposed mechanisms of copper extraction from acid sulphate solution.It was shown that an interfacial mechanism is very probable for compounds with long alkyl chains. For these compounds the extraction limiting step is the reaction between hydroxyoxime molecules present near the interface and the intermediate 1:1 complex.     

Effect of Hydrophobicity and Interfacial Activity of 2-Hydroxy-5-alkylbenzophenone Oximes upon the Rate of Copper Extraction from Acidic Sulfate Solution

Abstract

The rates of copper extraction from acidic sulfate solutions with 2-hydroxy-5-alkylbenzophenone oximes of various hydrophobicities were measured by means of the drop ascending method, and they are discussed from the view of hydroxyoxime partition between both extraction phases and hydroxyoxime interfacial activity. The measured extraction rates are compared with those predicted from partition and interfacial activity data for various versions of the extraction mechanism. The ratios of specific extraction constants for oximes of various hydrophobicities are estimated for the interfacial mechanism with the preadsorption of hydroxyoximes at the hydrocarbon/water interface. The order of the specific rate constants determined for the interfacial reaction is in agreement with the order of the free energy of hydroxyoxime adsorption at the hydrocarbon/water interface.     

Extraction of copper from dilute solutions by LIX 64N. Effect of dekalin and tetralin as diluents on the equilibrium and rate of mass transfer

Liquid-liquid equilibrium data and mass transfer rates for the extraction of copper from dilute aqueous sulphate solutions by LIX 64N with dekalin (decahydronaphthalene) and tetralin (1,2,3,4-tetrahydronaphthalene) as diluents are reported. The stripping of copper from the organic phase was also studied. For an initial copper concentration of 1.5 g dm^?3 extraction efficiency decreases as the concentration of tetralin increases in the diluent mixtures of dekalin-tetralin. This behaviour is explained as a result of the formation of oxime aggregates and the interaction between the oxime and the diluent. Initial rates of extraction and stripping were determined by the single drop technique. The linear relation between initial rates of extraction and the difference of interfacial tension between the extractant in the diluent and the diluent itself holds for the system under investigation.     

EXTRACTION MECHANISM OF PALLADIUM WITH DIDODECYLMONOTHIOPHOSPHORIC ACID IN HEPTANE DILUENT

ABSTRACT

Kinetic study of the extraction of palladium(D) with didodecylmonothiophosphoric acid in n-heptane diluent was carried out using a stirred transfer cell to clarify the extraction mechanism. The effect of surfactants on the kinetics of palladium extraction was also investigated, to elucidate the role of surfactants used in liquid surfactant membranes. Moreover, the interfacial tension between the organic and aqueous phases was measured to elucidate the adsorption equilibrium of the surfactants. It was found that the interfacial activity of each surfactant is higher than that of the extractant. In the kinetic study of palladium extraction, the experimental results of the extraction rate was analyzed by the interfacial reaction model, taking into account of the adsorption of the surfactant and extractant. The rate-determining step of palladium extraction was the complex formation between four chloro-palladium complexes and the extractant at the interface, and the extraction rate constants of each palladium species were obtained. The extraction rate of palladium in n-heptane diluent was much faster than that in toluene. Additionally, it was suggested that there was particular interaction between the surfactant and extractant at the interface. The effect of the surfactant on the extraction rate was explained by taking into account the adsorption of the surfactant at the interface.     

Extraction of copper from acid sulphate solutions by 2-hydroxy-5-(1,1,3,3-tetramethylbutyl)-benzaldehyde,-acetophenone and -benzophenone oximes

2-Hydroxy-5-(1,1,3,3-tetramethylbutyl)-benzaldehyde E-oxime ( 1 ), 2-hydroxy-5-(1,1,3,3-tetramethylbutyl)-acetophenone E-oxime ( 2 ) and 2-hydroxy-5-(1,1,3,3-tetramethylbutyl)-benzophenone E-oxime ( 3 ) were synthesized and used for copper extraction from acidic sulphate solutions. The dissociation constants of the phenolic group of the oximes and the stability constants for their complexes with copper were determined. An extraction model is discussed taking under consideration the association of the oxime and the solvation of the complex. It was found that 1 can extract copper more efficiently from acidic aqueous solutions and at a higher rate than 2 and 3. 1 is a stronger acid than 2 and 3 . However, it is a weaker acid than the Z isomer of 3 . The proposed model fits the experimental data well. When the oxime is used in excess, solvation of the copper complex seems probable.     

HS-LIX65N从氯化物介质中萃铜的萃取动力学研究

采用HS-LIX65N为萃取剂(稀释剂为Escaid 100)进行了从氯化物(CuCl_2-NaCl-HCl)介质中萃取铜的动力学研究.实验在一恒界面池(Lewis cell)中进行,本文着重研究了不同的两相组成对铜的萃取传质速率的影响.在判定HS-LIX65N从氯化物介质中萃取铜的控制机制为带有吸附和解吸过程的界面化学反应的基础上,确定了铜的1-2络合物(即CuR_2)的生成为反应控制步骤;而且实验结果表明,在一定的实验条件下,CuCl+是主要的被萃取组分.在理论分析的基础上,建立了如下萃取动力学模型:N_(cu)=[RH]i/a_(H~+)[1.791×10~(-5)(a_(cu~(2+))+1.882×10~(-4)(a_(CuCl~+)]用此模型计算所得结果与实验结果的平均偏差为5.29%.     

Study of the Kinetics of Copper Extraction with (anti)-2-Hydroxy-5-nonylbenzophenone Oxime Using a Rotating Diffusion Cell

Abstract

A rotating diffusion cell was used to study the chemical reaction in which copper is transferred from an aqueous sulfate phase to an organic phase containing a copper-complexing agent (purified anti-2-hydroxy-5-nonylbenzo-phenone oxime) dissolved in n-decane. A mathematical model was developed to describe the contributions of the kinetic and diffusive resistances to the overall resistance to mass transfer. Application of this model to the experimental data enabled an overall rate equation for the reversible copper extraction reaction to be written. The active oxime species in the extraction reaction was found to be the monomer with first-order kinetics. The extraction reaction rate was also found to be dependent on aqueous phase hydrogen ion concentration with negative first-order kinetics. The extraction rate constant was determined as 1.3 × 10^?5 cm/s. Assumption that the reverse rate is dependent on hydrogen ion concentration with first-order kinetics enabled the reverse rate constant to be calculated as 6.8 × 10^?3 cm⁴/mol·s.     

KINETICS MODEL FOR INTERFACIAL REACTION OF COPPER EXTRACTION WITH 1-(2'-HYDROXY-5'-NONYLPHENYL)-l-ETHANONE (E)-OXIME AND 1-(2'-HYDROXY-5'-METHYLPHENYL)-1-DECANONE (E)-OXIME

Abstract

A kinetic model for the interfacial reaction of copper extraction with Individual 1-(2'-hydroxy-5'-nonylphenyl)-1-ethanone (E)-oxime and 1-(2'-hydroxy-5'-methylphenyl)-1-decanone (E)-oxime having the same hydrophobicity was used to interpret the effect of hydroxyoxime partition and interfacial activity upon the rate of copper extraction from acidic sulfate solutions. Due to similar hydrophobicity of studied extractants the proposed model, which is very sensitive to the errors of the partition coefficient determination, cannot support any version of extraction mechanism.     

INTERFACIAL ACTIVITY OF HDEHP AND KINETICS OF NICKEL EXTRACTION IN VARIOUS DILUENTS

ABSTRACT

The interfacial behavior of HDEHP at various diluents/0.05M (H₂,Na₂)SO₄ interfaces was examined using the Drop Volume Method. Different adsorption isotherms such as the Gibbs and Szyszkowski were found as fits well to the experimental interfacial tension isotherms. The values of surface excess at saturated interface,calculated according to them by using the concentration of individual species (e.g. organic monomeric species),increase in the order: MIBK<chloroform <benzene～toluene～xylene<CCl₄ <n-hexane～n-heptane

The interfacial activity data were used to discuss the mechanism and kinetics of nickel extraction. It was shown that the interfacial mechanism is very probable and the extraction limiting step is the reaction between HDEHP molecules present near the interface and the intermediate 1:2 complex just as following

Ni(H₂O) ₄A_2(int,0) +2H₂A_2(int,0) =Ni(H₂O) ₂A₂˙2H₂A_2(int,0) +2H₂O_(int,0)

The investigation of the influence of diluent on the extraction rate supports the mechanism suggested.     

Kinetic Studies of Extraction and Stripping of Copper with Dibenzoylmethane

Abstract

Kinetic studies of the extraction of copper with dibenzoylmethane and the stripping of copper were carried out in a stirred transfer cell, along with a study of the extraction equilibrium of copper with the extractant at 303 K. The extraction and stripping rates were analyzed by a model of the interfacial reaction between the extractant and the adsorbed 1:1 copper chelate complex accompanied by the mass transfer steps of the species. Furthermore, the extraction rate was simulated by using the equilibrium and reaction rate constants obtained from the analysis.     

铜的反萃取动力学研究

本文用NaCl-HCl水相进行了从负载HS-LIX65N有机相中反萃取铜的动力学研究.实验是在与萃取动力学研究所用的同一恒界面池(Lewis cell)内进行的.实验结果表明:铜的反萃速率几乎与两相内搅拌器的转速无关,但却正比于两相间的界面积,再加上测得的高活化能值,表明了铜的反萃过程具有明显的界面化学反应控制的特征.根据实验结果建立了经验数学模型,又按照带有吸附和解吸过程的界面化学反应控制机理和水膜内化学反应控制机理分析了这一反萃动力学的过程机制.数据处理表明:此过程具有“真正的界面化学反应”(即带有吸附和解吸过程的界面化学反应)控制的特征.其数学模型为:N_(Ca)=5.7×10~(-8)[(?)_2]_b~(0.884)[H~+]_b~(0.758)[Cl~-]_b~(0.906)式中浓度单位为mol/l,计算值与实验值的平均相对偏差为0.5%.应予指出:不能完全排除水相侧扩散膜内的界面化学反应对铜的反萃传质的贡献.     

Copper extraction from diluted sulphate solutions by 2-hydroxy-5-tert-butylbenzaldehyde oxime

A study of the influence of the equilibrium pH of the aqueous phase and the oxime concentration in octane, isooctane, xylene and ethylene dichloride showed that 2-hydroxy-5-tert-butylbenzaldehyde oxime (HBBO) forms a yellow complex with copper with a molar ratio of ligand: metal equal to 2:1. The same results were obtained using Job's and slope ratio methods. The diluents examined influence the copper extraction by HBBO, especially at low pH values in the aqueous phase. The order of extractability is as follows: isooctane=octane>xylene>ethylene dichloride. At low pH values, HBBO shows greater extraction power than 2-hydroxy-alkyl-benzophenone oximes. Computer calculations suggest that polymerisation of the complex does not occur. However, a solvation of the complex occurs when excess of the oxime is used.     

SOLVENT EXTRACTION OF COPPER(II), NICKEL(II), AND COBALT(II) FROM SODIUM CHLORIDE SOLUTIONS BY OCTANAL OXIME

The extraction of divalent copper, nickel, and cobalt from sodium chloride solutions with octanal oxime (OCOX) was found to proceed by the following reaction:

The association of octanal oxime in toluene was taken into account in the modelling of the extraction reaction, and the formation constants for dimers and trimers were calculated using vapour-pressure osmometry. Stability constants for the formation of aqueous copper-chloro species were also calculated.     

Interfacial activity of 4-alkylphenylamines and the rate of palladium(II) extraction

Interfacial tension isotherms were determined in hydrocarbon-water systems for 4-alkylphenylamines containing from 6 to 16 carbon atoms in their alkyl chains, and the surface excess isotherms were computed and interpreted using various adsorption isotherms. Palladium(II) was extracted with 4-alkylphenylamines from 3 M HCI solutions. The maximum extraction rate of palladium(II) is observed for 4-decyl- and 4-dodecylphenylamines which exhibit good interfacial activity. Compounds soluble in the aqueous phase (4-hexylphenylamine) or in toluene (4-hexadecylphenylamine) extract palladium(II) slower than 4-decyl- and 4-dodecyl- phenylamines.     

On the permeation rate of copper extraction through liquid membranes

The understanding of the permeation rate of metal ions through liquid membranes is important for the design of such systems. In this paper, the permeation rates of copper ions through liquid surfactant membranes, including interfacial reaction rates and the diffusion rate of the copper ion, were analyzed using a model based on a mobilized hollow spherical globule configuration. The analysis shows that the extracting reaction is dominant at the external interface of the membrane and the stripping reaction is dominant at the internal interface; this means the reactions at both interfaces are not in equilibrium during the course of extraction. It also shows that the extraction rate, the diffusion rate and the stripping rate are not of equal value, especially at the early stage of the run.     

辐射交联聚丙烯腈偕胺肟纤维的制备及其对钒(Ⅲ)的吸附研究

采用60Coγ射线对聚丙烯腈纤维进行预辐射交联,并经偕胺肟化反应,制备了含有偕胺肟基的聚丙烯腈螯合纤维,用于钒(Ⅲ)离子的吸附行为研究。结果表明,辐射交联可以有效提高聚丙烯腈纤维的肟胺化反应速率;经肟胺化和吸附之后的纤维力学性能良好;较高的肟胺化程度导致聚丙烯腈纤维对三氯化钒具有很高的吸附容量。     

Extraction of copper from acid sulphate solutions by 2-hydroxy-5-n-nonyl and 2-hydroxy-4′-n-nonylbenzophenone oximes

The study of copper extraction shows that the position of the chain (5 or 4′) does not influence the statics of copper extraction from ammonia solutions by alkyl derivatives of 2-hydroxybenzophenone oxime. Acid solutions of 2-hydroxy-4′-n-nonylbenzo-phenone oxime can extract more copper than 2-hydroxy-5-n-nonylbenzophenone oxime, but less than 2-hydroxy-5-n-alkylbenzaldehyde oxime.     

THE KINETICS OF COBALT(II) EXTRACTION WITH EHEHPA IN HEPTANE FROM ACETATE SYSTEM USING AN IMPROVED LEWIS CELL TECHNIQUE†

ABSTRACT

The cobalt(II) extraction kinetics and mechanism with EHEHPA (2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester) were investigated by an improved constant interfacial area stirred cell. The effects of the buffer species, stirring rate, temperature, specific interfacial area and surfactants on the extraction rate showed that the extraction regime was dependent on the extraction conditions and the most probable reaction zone was at the liquid-liquid interface. This extraction process was reaction controlled at lower concentration of the reactants, while it was mixed chemical reaction-diffusion or diffusion controlled only for higher concentration of the reactants. An interfacial extraction reaction model with diffusion was derived. The kinetics of the extraction process was simulated with this model.     

Kinetics and Mechanism in the Liquid-Phase Hydrogenation of Maleic Anhydride and Intermediates

The influence of zinc oxide on the kinetics and mechanism of the liquid-phase hydrogenation of maleic anhydride (MA) and intermediates was investigated on copper-based catalysts. No influence of zinc oxide on the hydrogenation of maleic anhydride was observed in previous experiments. The discontinuous hydrogenation of succinic anhydride (SA) resulted in the formation of γ-butyrolactone (γ-BL) and 1,4-butanediol (1,4-BD) on a copper/zinc catalyst. On a zinc-free copper catalyst only γ-butyrolactone was formed while the hydrogenation of γ-butyrolactone to 1,4-butanediol was inhibited. It was observed that succinic anhydride which is adsorbed on the copper surface of the catalyst prevents the adsorption of γ-butyrolactone. On copper/zinc catalysts the reversible adsorption of succinic anhydride on the inactive zinc oxide crystallites, which led to a reversible decrease of the carbon balance, is responsible for a decrease of the succinic anhydride coverage of the copper sites. It appears that the decrease of the succinic anhydride coverage of the copper surface is proceeding by surface diffusion of succinic anhydride to the adjacent zinc oxide crystallites. On this basis two different reaction pathways via succinic anhydride adsorbed on the copper surface and via succinic anhydride adsorbed on the zinc oxide crystallites were proposed for the hydrogenation of maleic anhydride and intermediates. Kinetic modeling of the reaction pathway taking into account both reaction pathways led to good agreement of calculated and experimental results.