Effect of a water-insoluble organic acid on amine extraction of acetic acid from aqueous solutions. Equilibrium studies

The effect of a water-insoluble organic acid, di(2-ethylhexyl)phosphoric acid (D2EHPA), on the extraction equilibrium of acetic acid from aqueous media with xylene solutions of tri-n-octylamine (TOA) was systematically investigated. In the absence of D2EHPA, the formulation of the extracted species in the organic phase and equilibrium constants for the formation of these species were numerically determined. Synergistic and antagonistic effects on the extraction of acetic acid were observed in the presence of D2EHPA, mainly depending on the concentration of TOA and the concentration ratio of D2EHPA to TOA. Finally, the influence of temperature on the extraction of acetic acid with TOA and/or D2EHPA was investigated.     

Extraction and Stripping Behavior of Iron (III) from Phosphoric Acid Medium by D2EHPA Alone and Its Mixtures with TBP/TOPO

In the present study an attempt has been made to understand the extraction and stripping behavior of iron (III) with D2EHPA alone and its mixture with TBP or TOPO in phosphoric acid medium. Effect of variables such as concentrations of iron (III), phosphoric acid, and phosphate in the aqueous phase, D2EHPA, TBP, and TOPO concentrations in the organic phase and temperature on the extraction process has been studied. The extraction of iron (III) decreased with increase in phosphoric acid concentration. The increase in D2EHPA concentration increased the extraction of iron (III). The presence of TOPO or TBP with D2EHPA showed antagonism. The increase in temperature decreased the extraction of iron (III) with D2EHPA alone and its mixture with either TOPO or TBP showing the exothermic nature of the extraction reaction. The stripping of iron (III) by various reagents followed the order: oxalic acid > phosphoric acid > hydrochloric acid > sulphuric acid > mixture of sulphuric and hydrofluoric acids > ascorbic acid > citric acid irrespective of extraction systems. Higher temperature favors the stripping. The effect of diluents on iron (III) extraction has also been studied. The mechanism of extraction has been explained in the light of the results obtained.     

Synergistic extraction and separation of Fe(III) and Zn(II) using TBP and D2EHPA

Waste chloride pickle liquors from hot-dip galvanizing plants, steel plants and flue dust contain reasonable amounts of heavy metals such as Zn, Cr, Ni, etc. Iron is invariably associated with most of these materials and comes into solution during leaching. Thus, the synergistic extraction of zinc(II) and iron(III) from leach solutions in tri-n-butyl phosphate (TBP)–di(2-ethylhexyl) phosphoric acid (D2EHPA) system diluted in kerosene was investigated. The Zn and Fe concentrations in the leach liquor used in the present study were 2 g/L. Experiments were carried out in the pH range of 0.5–4.0, temperature of 25°C, using sole D2EHPA, sole TBP and D2EHPA–TBP mixtures at different ratios. Results showed that the co-extraction of zinc(II) and iron(III) increased with increasing equilibrium pH using D2EHPA. It is demonstrated that the mixtures of TBP and D2EHPA are more efficient and selective than D2EHPA alone. At low pH values, the separation factor is low when pure D2EHPA is used as an extractant; however, using TBP as a synergist, the separation factor increases and results in a better separation of zinc from iron. Increasing TBP to D2EHPA ratios in the organic phase caused a slight shift to the right in the extraction isotherm of iron and a marked shift to the right in the extraction isotherm of zinc, and the maximum separation factor of 13.3 × 10³ was achieved at a TBP to D2EHPA volume ratio of 4:1 (0.58 M TBP: 0.12 M D2EHPA). Furthermore, the effect of equilibrium pH, organic to aqueous phase ratio and Cl^? concentration on the selective extraction was investigated. Using two extraction stages at the O/A ratio of 2:1 and pH_e (equilibrium pH) of 3 and 1 for zinc and iron, respectively, 99% of zinc(II) and 96.25% of iron(III) were extracted.     

Extraction of 2-chloroethanol from aqueous solutions by trioctylamine

The trioctylamine (TOA) with kerosene as a diluent was used to separate 2-chloroethanol from aqueous hydrochloride acid solution. The stoichiometry of complex data was studied with infrared spectroscopic and the result shows that the ratio of 2-chloroethanol to amine in the complex was 1:2. The equilibrium constant was assumed to be 4.05 × 10⁵. Effects of temperature, equilibrium pH, TOA concentration, organic phase to aqueous (O/A) phase ratio and contact time on extraction yield of 2-chloroethanol were investigated. The results show that extraction yield can reach 58.2% under the optimum conditions.     

Extraction equilibria and separation of phenylalanine and aspartic acid from water with di(2‐ethylhexyl)phosphoric acid

The distribution equilibria of single and binary L ‐phenylalanine and L ‐aspartic acid between water and a kerosene solution of di(2‐ethylhexyl)phosphoric acid (D2EHPA) were studied. It was shown that the distribution ratios of phenylalanine generally increased with increasing aqueous pH (2–5) in the D2EHPA concentration range 0.1–0.5 mol dm^?3, but those of aspartic acid decreased with increasing solution pH. Different reaction stoichiometries were proposed for the extraction of phenylalanine and aspartic acid under the conditions studied. The extraction equilibrium constants were obtained. Competitive extraction in binary systems was more apparent in the pH range where the cationic form of amino acids was not predominant. The present results indicated that selective separation of phenylalanine to aspartic acid was possible with this cationic extractant when they were extracted at higher pH and stripped using higher acidity of HCl solution. Copyright © 2006 Society of Chemical Industry     

Selective and Synergistic Extraction of Nickel from Simulated Cr-Ni Electroplating Bath Solutions using LIX 63 and D2EHPA as Carriers

The main goal of the present study is to explain synergistic extraction of nickel from simulated Cr-Ni electroplating bath solutions (SEBS) using 5,8-diethyl-7-hydroxydodecane-6-one oxime (LIX 63) and di-(2-ethylhexyl) phosphoric acid (D2EHPA) as extractants by emulsion liquid membrane (ELM) technique. The importance of membrane composition and aqueous phase properties on nickel extraction percentage has been highlighted for the selective extraction of nickel. Some important parameters like acid concentration, stripping solution type and concentration, mixing speed, extractant concentrations, phase ratio, and surfactant concentration was studied to improve the extraction and stripping efficiencies. Higher than > 99% of nickel was recovered at optimum conditions within 6 min. The higher separation factors (β_Ni/Cr) were obtained as 580. As a result, the nickel extraction kinetic with D2EHPA has been defined as faster than LIX63. So, the kinetic transport of nickel mainly depends on LIX63 than D2EHPA. According to these results, D2EHPA behaves as a synergistic extractant in the present extraction mechanism.     

Removal of Cu2+ from Water Using Liquid-Liquid Microchannel Extraction

The very good extraction selectivity of Cu²⁺ from water was demonstrated with a new microchannel equipment, by employing di-(2-ethylhexyl)phosphoric acid (D2EHPA) as an extractant and kerosene as a solvent. The effects of different experimental parameters on the extraction efficiency E, the volumetric mass transfer coefficient K_La, and the entrainment were experimentally investigated. The results showed that the extraction efficiency increased with increasing temperature, extractant concentration, phase ratio (organic/aqueous), and pH. The total flow rate, phase ratio, and pH were found to have a great effect on the mass transfer, whereas the temperature and the extractant concentration showed little effect.     

Synergistic effect of various neutral donors in D2EHPA for selective neodymium separation from lanthanide series via HFSLM

The separation of Nd(III) from lanthanide series via hollow fiber supported liquid membrane (HFSLM) using synergistic extractant was investigated. Optimum extraction and stripping obtained were 94.5% and 85.1% using D2EHPA and TOPO mixtures (0.5:0.5 M/M) as the synergistic extractant. Reaction order for both extraction and stripping were first-order with rate constants of 1.444 and 1.338 min⁻¹, respectively. The experimental results were used to correlate with the models. Results showed that the concentration of Nd(III) from the experiment fitted in well with the model results. The average deviation was 1.95% and 2.18% for predictions in both feed and stripping sides, respectively.     

Equilibrium studies on reactive extraction of lactic acid with an amine extractant

Equilibrium studies on the extraction of lactic acid from aqueous solutions with tri-n-octylamine (TOA) in xylene were made in the temperature range 293–323 K. The formulation of the extracted species in the organic phase and the corresponding equilibrium constants were numerically determined at different temperatures. Also, the apparent thermodynamic functions were calculated. Finally, the effect of a water-insoluble organic acid, di(2-ethylhexyl)phosphoric acid (D2EHPA), on this extraction was investigated. Synergistic and antagonistic effects were observed in the presence of D2EHPA, mainly depending on the concentration ratio of D2EHPA to TOA.     

中空纤维支撑液膜萃取Cu(II)的传递性能

The transport of Cu(II) from aqueous solutions containing buffer media through hollow fiber supported liquid membrane (HFSLM) using di(2-ethylhexyl) phosphoric acid (D2EHPA) dissolved in kerosene as membrane phase and hydrochloric acid as striping phase was investigated. A set of factors were studied, including tube side velocity, shell side velocity, pH of the feed phase, Cu(II) concentration in the feed phase, buffer media concentration and D2EHPA concentration in the membrane phase. Experimental results indicate that the mass transfer coefficient increases with increasing both carrier concentration in the organic phase and flow rates on the tube side and shell side, and decreases with increasing initial Cu(II) concentration in the feed phase. With increasing pH value and acetate concentration in the feed phase, the mass transfer coefficient reaches a maximum value then decreases. The optimal operating conditions are obtained at pH value of 4.44 and 0.1 mol&;#8226;L－1 acetic ion concentration in feed phase, and carrier volume fraction of around 10% in kerosene as organic phase. A mathematical model of the transport mechanism through HFSLM is devel-oped. The modeled results agree well with the experimental ones.     

二（2-乙基已基）磷酸萃取氨基苯甲酸的平衡特性

A series of extraction equilibrium experiments for aminobenzoic acid with di(2-ethylhexyl)phosphoric acid (D2EHPA) dissolved in n-octane or 1-octanol was carried out. The effects of aminobenzoic acid concentration,D2EHPA concentration and pH on the distribution ratio were discussed in detail. The infrared spectra of the organic phase loaded with solute illustrated that pH had little effect on the structure of the complex formed. There proceed ion association and cation-exchange.reaction in the extraction. An expression of the equilibrium distribution was proposed.     

Study and Optimization of Amino Acid Extraction by Emulsion Liquid Membrane

Abstract

A batch extraction of an essential amino acid, phenylalanine, from an aqueous solution of different concentrations by an Emulsion Liquid Membrane (ELM) was developed using D2EHPA as a cationic carrier, Span 80 as the surfactant, paraffin, and kerosene as the diluents, and HCl as the internal electrolyte. All effective parameters such as the initial pH of the aqueous external phase, the electrolyte concentration in the aqueous internal phase, carrier, and surfactant concentration in the emulsion, the volume ratio of the organic to aqueous internal phase (Roi), the volume ratio of the W/O emulsion to the aqueous external phase (Rew) and time were examined and optimized using the Taguchi method. Applying the Taguchi method to analyze the experimental results, the effects and contribution of each of the factors on the extraction efficiency were obtained. The results obtained from the experiments illustrated that with a stable emulsion, by optimizing all the effective parameters, a considerable amount of phenylalanine can be extracted in a short time with an acceptable ratio of swelling and breakage.     

草酸强化三价铁离子的反萃性能

二(2-乙基己基)磷酸(P204)常作为溶液净化除铁的萃取剂，P204-磺化煤油体系中Fe³⁺与有机相形成络合能力较强的萃合物，使得Fe³⁺反萃比较困难，需采用较高浓度的酸作为反萃剂，但高浓度的酸会破坏有机分子的结构，影响萃取剂循环利用。针对P204-磺化煤油负铁有机相反萃困难的问题，提出利用草酸为反萃剂对负载1g/L铁的P204-磺化煤油有机相的反萃行为进行研究，考察了反萃转速、草酸浓度、反萃温度、反萃时间和相比对Fe³⁺反萃率的影响。结果表明：以反萃转速200r/min，草酸0.4mol/L，反萃时间10min，反萃温度40℃，反萃相比1∶1，采用二级逆流萃取方式，铁的反萃率可以达到99%以上；Fe³⁺反萃过程是吸热反应，其反应的焓变为81.58kJ/mol，反萃过程符合准一级反应动力学方程，对应活化能为49.5kJ/mol。进一步研究了反萃后P204-磺化煤油有机相对Fe³⁺的萃取性能。结果表明：经5次草酸反萃后的P204-磺化煤油有机相萃铁性能几乎不变，对比于高浓度的酸反萃，草酸反萃简化了反萃流程，降低了萃取剂的消耗。     

二(2-乙基己基)磷酸萃取L-色氨酸

以二 (2 -乙基己基 )磷酸 (D2EHPA) -正辛烷 (体系A)及D2EHPA -正辛醇 +正辛烷 (体系B)萃取L -色氨酸为对象 ,研究了D2EHPA浓度、L -色氨酸初始浓度、稀释剂组成以及pH值对萃取平衡分配系数的影响 .结果表明 ,在实验研究涉及的pH值 (1.0     

Synergistic Effect of D2EHPA and Cyanex 272 on Separation of Zinc and Manganese by Solvent Extraction

The effect of bis-2-ethylhexylphosphoric acid (D2EHPA), bis (2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272), and tri-butyl phosphate (TBP) and their mixtures in various proportions for the separation and extraction of zinc and manganese from sulfate solutions were investigated. Experiments were carried out in the pH range of 0.5–5.0 at 25, 40, and 60°C. It was shown that the extraction of zinc and manganese by D2EHPA and/or Cyanex 272 can be increased by the increase in pH and temperature. The synergistic extraction and separation of zinc and manganese with a mixture of D2EHPA and Cyanex 272 was studied and the results showed that mixing the two extractants improved the extraction capacity of the mixture. Increasing the D2EHPA to Cyanex 272 ratio in the organic phase, caused a right shifting of extraction isotherms of manganese and zinc; shifting the manganese curve was more than zinc. The manganese curve had considerable right shifting with 5% D2EHPA and 15% Cyanex 272. TBP did not affect the zinc (Zn) and manganese (Mn) extraction. The stoichiometric coefficients of Zn and Mn were determined with 20% and 5% D2EHPA and 15% Cyanex 272 by applying the slope analysis method. The organic phase was stripped by sulfuric acid.     

采用不同载体的中空纤维更新液膜Cu(Ⅱ)传质的研究(英文)

The extraction ability of organophosphorus extractant D2EHPA (di-2-ethylhexyl phosphoric acid) and hydroximic extractant Lix984N are investigated by the extraction equilibrium experiments. Effects of carrier concentration and organic/aqueous volume ratio on the mass transfer of hollow fiber renewal liquid membrane (HFRLM) are studied. Results show that, in the extracting process, kerosene and n-heptane are more suitable than methyl-isobutyl ketone, butylacetate and benzene as the diluents of D2EHPA or Lix984N. The favorable feed pH is 4.4 for D2EHPA and 2.6 for Lix984N. The mass transfer flux of HFRLM increases with carrier concentration and finally reaches a plateau. The mass transfer flux and the overall transfer coefficient increase with the or-ganic/aqueous volume ratio, reach the maximum and then decrease.     

Distribution Behavior of Amino Acid by Extraction with Di(2-ethylhexyl) Phosphoric Acid

Abstract

The distribution equilibrium of l-tryptophan (l-Trp) by extraction with di(2-ethylhexyl) phosphoric acid (D2EHPA) dissolved in n-hexane was studied. The effects of L-Trp and D2EHPA concentrations, pH, and ionic strength, particularly of L-Trp loading in the organic phase, on extraction equilibrium were examined in detail. When the amino acid loading ratio (the molar concentration ratio of the equilibrium amino acid in the organic phase to the initial dimeric D2EHPA) was less than 3 × 10^?3, one L-Trp molecule was extracted by forming a complex with four monomeric D2EHPA molecules, and the extraction equilibrium constant (K _e) was determined to be 0.045 dm³/mol. Above this loading ratio the equilibrium formula did not hold, and the apparent equilibrium constant (K _a) increased significantly with increasing loading ratio. The phenomenon was explained by taking into account two parallel reactions in which fewer D2EHPA molecules, two and one respectively, were needed to extract one l-Trp molecule.     

Process for the Recovery of Cobalt and Nickel from Sulphate Leach Liquors with Saponified Cyanex 272 and D2EHPA

Abstract

In this paper, a process is reported for the recovery of cobalt and nickel from copper raffinate solutions using partially saponified Cyanex 272 and D2EHPA as the extractants. The aqueous feed contains 1.65 g/L cobalt and 16.42 g/L nickel. More than 99.9% cobalt separation was achieved with 0.13 M Cyanex 272 (60% neutralized with alkali) in two counter‐current stages at an aqueous to organic phase ratio of 1.1:1. Co‐extraction of nickel was 0.18% only. Stripping of cobalt from a loaded organic phase was carried out with synthetic spent electrolyte solution at an organic to aqueous phase ratio of 2.5 in two counter‐current stages to generate a pregnant electrolyte solution to produce cobalt metal by electrowinning. Similarly, optimum conditions for nickel extraction with 60% neutralized 1 M D2EHPA at O/A ratio of 1.4 in 2 two stages and stripping of metal with synthetic spent electrolyte at O/A ratio of 1.6 in two stages were standardized. Extraction and stripping efficiencies were >99% and the flowsheet of the process is demonstrated.     

非离子表面活性剂TX114浊点萃取D2EHPA的规律

引言浊点萃取[1-2]是利用表面活性剂水溶液的增溶和分相行为实现溶质富集的分离技术。由于分相后表面活性剂的富集相(亦称凝聚相)与水相的体积比非常小(0.007～0.04)[3],所以,对于被增溶的物质能够提供非常高的富集倍数和萃取效率。目前浊点萃取技术主要广泛应用于痕量有害物质     

二(2-乙基己基)磷酸萃取L-苯丙氨酸

以二（2-乙基己基）磷酸（D2EHPA）-正辛烷萃取L-苯丙氨酸为对象,研究了D2EHPA浓度、L-苯丙氨酸初始浓度以及pH值对萃取平衡分配系数的影响。不同pH值下负载有机相的红外谱图分析表明,D2EHPA与L-苯丙氨酸形成的萃合物结构与pH值无关。提出了在萃取过程中同时存在着离子交换反应和质子转移反应的观点。1个氨基酸分子与2个二（2-乙基己基）磷酸二聚体相结合。本文建立的萃取平衡分配系数关联式,拟合精度令人满意。