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.     

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.     

ACTIVITIES OF METAL EXTRACTANTS AS DETERMINED FROM INTERFACIAL TENSION ISOTHERM

Activity/correction coefficients of hydroxyoxime extractants and triisooctylamine in extraction systems containing non-solvating diluents were computed from the interfacial tension isotherms. The deviations from the Gibbs isotherm were considered. in which concentration instead of activities were used. The interfacial tension isotherms were matched by the spline function and the polynomial Computed activity/correction coefficients can be used to model the equilibrium of copper and palladium (II) extraction.     

Separation of Cobalt and Nickel by Liquid Surfactant Membranes Containing a Synthesized Cationic Surfactant

ABSTRACT

Separation of cobalt(II) and nickel(II) by using a hydroxyoxime extractant has been investigated both in liquid-liquid extraction and in a liquid surfactant membrane(LSM) system. In the liquid-liquid equilibrium extraction studies, hydroxyoximes showed significant extractability for nickel ions, although LIX 84 was found to have exceptional chelating affinity for nickel ions. In the LSM system functionalized by hydroxyoxime, the cobalt ions were efficiently separated from nickel ions as a result of slower permeation of nickel chelates across the emulsion membrane. More complete cobalt recovery was achieved in the LSMs dosed with LIX 860 than when the same carrier was applied to the liquid-liquid extraction system. Furthermore, cobalt permeation rate was enhanced threefold when a quaternary ammonium type of cationic surfactant was used as an emulsifier due to carrier interaction with surfactant at the reaction interface. The permeation mechanism of ions in LSMs was elucidated by an interfacial reaction model which took into account the adsorption of the carrier and surfactant at the reaction interface.     

Hydrophile lipophile balance of hydroxyoximes in McGowan scale and their partition and extraction properties

Hydroxyoxime hydrophobicity was characterized by hydrophile lipophile balance in McGowan scale, and the relationship's log partition coefficient vs HLB^Ga and extraction rate vs HLB^Ga were discussed. The effect of the alkyl length and structure upon hydroxyoxime hydrophile lipophile balance and partition coefficients can be qualitatively considered using the effective length of the alkyl. The partition data for homologous series can be predicted from HLB^Ga. Relationships between extraction rate and HLB^Ga do not support the traditional view of the extraction mechanism. It supports the idea of the mechanism change from the bulk aqueous to the interfacial mechanism with the increase in hydroxyoxime hydrophobicity.     

RATE OF COPPER EXTRACTION AND INTERFACUL ACTIVITY OF MODEL β-DHCETONES

ABSTRACT

Interfacial tension isotherms and rate of copper extraction were studied for model β-diketones of LIX 54 and of pyrazolone type. The effect of the position and structure of the hydrophobic alky1 group upon interfacial activity and rate of extraction is discussed. The preadsorption of extractant molecules at the water/hydrocarbon interface is not needed to obtain a quick and effective extraction.     

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.     

不同平均分子量及其分布烷基芳基磺酸盐的制备与性能

以直链α烯烃、苯、甲苯、混和二甲苯等为原料,采用原位离子液体催化烷基化反应分别合成出不同碳数的直链烷基苯、烷基甲苯和烷基二甲苯,经降膜式磺化、中和反应、提纯等方法制得不同相对分子质量的烷基芳基磺酸盐,其纯度均大于97.0%,仪器分析证明了其结构与设计相符。不同平均分子量、不同分布形式的磺酸盐体系降低油水界面张力能力不同;平均分子量为432、递增分布和反正态分布体系与碱、聚合物组成的三元复合体系在人造岩心上,室内模拟驱油可在水驱基础上提高采收率22%以上。     

5709-庚烷从硫酸介质中萃取钴、镍体系的界面特性——(Ⅱ)钴、镍萃取动力学反应控制步骤的判定

在实验测定5709-庚烷草取钴、镍体系界面张力的基础上建立了相应体系的界面张力等温线模型。探索了由萃取体系界面特性数据判定萃取动力学过程控制机制的途径,即由界面张力等温线计算得到界面超量等温线,然后再与界面化学反应机制进行关联,进而确定反应中对应萃取剂的反应级数。按此论证了5709-庚烷萃取钴、镍的界面化学反应过程为: 其中被萃金属离子的1-2络合物的生成反应为过程控制步骤。     

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.     

Effects of hydrophobic chain length on temperature dependence of monolayer behavior of ester-type tartaric geminis

Ester-type tartaric gemini amphiphiles bearing two carboxyl groups and two hydrophobic alkanoyl groups were prepared from L-tartaric acid, and the pressure-area (π-A) isotherms for a series of symmetric tartaric gemini amphiphiles were measured by the conventional film-balance technique. The effects of the length of the hydrophobic alkanoyl chains and of the subphase temperature (T(sub)) on the π-A isotherms for these compounds were examined. As the length of the hydrophobic alkyl chain increased, a more tightly packed monolayer was formed at the air-water interface. The melting temperature (T(m)) of the monolayer on the water surface was evaluated from the subphase temperature (T(sub)) dependence of the monolayer static elasticity ε(s), based on a π-A isotherm. A clear relationship between T(m) and hydrophobic carbon number (n) was observed for 2D monolayers of tartaric geminis on water surfaces, as well as for fatty acids and/or 3D solids.     

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.     

Surface and Self-Aggregation Properties of Bis-Benzimidazolones Derivatives of <Emphasis Type="SmallCaps">d</Emphasis>-Glucose

The surface and self-aggregation properties in water of a new series of amphiphilic homologues, bis-benzimidazolone derivatives of d-glucose, were investigated. Parameters such as the maximal surface excess concentration, minimal area per molecule at the interface, and critical micelle concentration (CMC) were found to be significantly dependent on the hydrophobic alkyl chain length. The synthesized compounds form micelles at remarkably low concentrations, and CMCs derived from surface tension measurements show a minimum as a function of the alkyl chain length; this unusual trend can be attributed to the formation of submicellar aggregates in compounds with long alkyl chains, as evidenced from fluorescence probe spectroscopy data. At high surfactant concentrations, lyotropic liquid crystalline phases with hexagonal structure are formed. Small angle X-ray scattering measurements indicate that the characteristic nanoscopic lengths increase with water swelling and alkyl chain length.     

Discussion of the Physicochemical Effects of Modifiers on the Extraction Properties of Hydroxyoximes. A Review

Abstract

The physicochemical aspects of hydroxyoxime modification with various modifiers containing oxygen atoms are discussed. This kind of modification is unique to hydroxyoxime reagents, which form weak intramolecular and intermolecular hydrogen bonds. These bonds can easily be destroyed not only by modifier molecules (alcohols, alkylphenols, and esters) but also by solvating diluents. Alcohols are stronger modifiers than alkylphenols. The drawback of these modifiers is their strong self‐association, which is eliminated in esters and sterically hindered alcohols. The extraction properties of strong hydroxyoxime extractants can also be modified by adding weak reagents (hydroxyoximes or β‐diketones), which form co‐associates with strong extractants. The use of sterically hindered esters seem rational for two reasons: they inhibit hydroxyoxime adsorption at the hydrocarbon/water interface with oximino group penetrating the aqueous layers; and they show negligible adsorption. Due to these phenomena, hydroxyoxime extractants are more stable, and a retardation of the extraction is not observed in the presence of hindered esters. There is currently no general explanation of the chemistry of modification. Many published works focus only on the interactions of modifiers with extractants, neglecting the interactions with metal complexes. In order to achieve a substantial progress in our understanding of the phenomenon of modification, interactions between complexes and modifiers must be studied and explained.     

The effect of amphiphilic salts on the interface of two immiscible liquids

Calculation of the thermodynamic characteristics of the interface of two immiscible electrolyte solutions (ITIES) was carried out using the self-consistent mean-field theory for adsorption and/or aggregation developed by Scheutjens and Fleer (1). The effect of tetraalkyl-ammonium-halogenid salts on the interfacial tension of 1,2-dichloro-ethane-water system was calculated for different alkyl groups, hence for different amphiphilic salts. For comparison, experimental determination of the interfacial tension was also carried out using a dynamic drop-weight method. It is found that the interfacial tension is significantly reduced due to the presence of the salts and the effect is larger for larger alkyl groups. Qualitative agreement was found between the calculated and the measured data. The model calculations showed also that the concentration of water near the interface may change non-monotonously.     

INTERFACIAL COMPOSITION OF MICROEMULSIONS: MODIFIED SCHULMAN-BOWCOTT MODEL

The interfacial composition of oil-external microemulsions formed with sodium stearate, pentanol, brine and various oils (octane, dodecane and hexadecane) was determined in terms of moles of alcohol per mole of surfactant present at the interface (niⁱ_a/n_3,) using a modified three compartment Schulman-Bowcott model. The modified model takes into account the solubility of pentanol in aqueous and hydrocarbon phases. For a constant brine/surfactant ratio, it was found that the value of (niⁱ_a/n_3,) was highest for dodecane containing microemulsion which corresponded to the maximum solubilization of brine in this microemulsion at optimal salinity. This behavior is explained on the basis of chain length compatibility in microemulsions. The optimal salinity for solubilization increased with the chainlength of oil.     

The Influence of Alkyl Chain Length and Steric Effect on Extraction of Zinc(II) Complexes with 1‐Alkyl‐2‐Methylimidazoles

Abstract

The extraction of Zn(II) complexes with six 1‐alkyl‐2‐methylimidazoles (alkyl is from C₅H₁₁ up to C₁₂H₂₅) from nitric solution was studied as a function of pH of the aqueous phase. As the organic solvents toluene, p‐xylene and 1,2,3,4‐tetrahydronaphthalene were used. The stability constants of the complexes in the aqueous phase as well as partition constants of the extractable species were determined. It was demonstrated that both the stability constants (β_c) and the partition constants (P_c) of the complexes increased with increasing alkyl chain length. Pseudo‐tetrahedral complexes were found to dominate at the second and third complexation steps, thus increasing the stability constants and facilitating extraction of the Zn(II) complexes with 1‐alkyl‐2‐methylimidazoles.     

ELECTROPHORETIC MOBILITY OF OIL DROPS IN THE PRESENCE OF SOLVENT EXTRACTION REAGENTS

Abstract

The electrophoretic mobility (EM) of hexane and toluene droplets dispersed in aqueous solution has been investigated as a function of pH in the presence and absence of 5,8-diethyl–7–hydroxy–6–dodecanone oxime (the active extractant in the Henkel reagent, LIX63), Dinonylnaphthalene sulfonic acid (HDNNS), di(2-ethylhexyl) phosphoric acid (HDEHP) and tricaprylyl methyl ammonium chloride (Aliquat 336). Both hexane and toluene droplets were found to be negatively charged at pH > 3, with the absolute EM increasing with pH; the toluene droplets were more negatively charged than the hexane droplets. The hydroxyoxime reagent had no significant effect on the EM, whereas the addition of HDNNS and HDEHP dramatically enhanced the negative charge at the organic/ water interface. In the presence of 1·5 × 10^?4 kmol m^?3 Aliquat 336, the organic drops became less negatively charged and eventually acquired a positive charge at pH < 9. The results are explained In terms of the preferential adsorption of the aqueous phase hydroxyl ions and the polar groups of the various extractants at the organic/water interface.     

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.     

Nickel extraction by 2-hydroxy-5-tert-butylbenzaldehyde oxime

Nickel extraction from aqueous solutions between pH 3 and 10 using 2-hydroxy-5-t-butylbenzaldehyde oxime was investigated. Iso-octane, octane, xylene and dichloro-ethane were used as diluents. It was found that nickel extraction is dependent upon the equilibrium pH, the mol ratio of oxime : nickel and the nature of the diluent. The composition of the nickel-oxime complex is in the ratio of 1:2. Extraction data, infrared spectra and cryoscopic measurements have shown the association of the oxime in the organic phase and the solvation of the nickel complex by the oxime molecules. The degree of solvation was found to be higher in dichloroethane than in octane.