EXTRACTION OF TITANIUM(IV) BY MIXTURES OF MONO- AND DH(2-ETHYLHEXYL) PHOSPHORIC ACID ESTERS

ABSTRACT

Solvent extraction of titanium(IV) from hydrochloric acid solutions by mixtures of mono- and di-2-ethylhexyl phosphoric acid esters (MEHPA and DEHPA) has been investigated as a function of HC1 concentration in the aqueous phase and extractants concentration in the organic phase

It was found that MEHPA extracts Ti, 3 orders of magnitude more efficiently than DEHPA. Efficiency of extraction by MEHPA does not depend on acid concentration in the aqueous phase in the range of 0·1 – 8·8 mole/Kg. As a rule Ti/MEHPA ratio in the complex is 1/2. At low aqueous phase acidities (0·1–1·0 mole/Kg HCl) formation of six- (or eight-) coordinate bidentate hydrated Ti(IV)-2MEHPA complexes is suggested. At acidities above 7·0 mole/Kg HC1 titanium forms tridentate six- (or eight-) coordinate complexes. At medium acidities (2·0–6·0 mole/Kg HCl) mixtures of these complexes are formed. Prolonged mixing of the phases or aging of the organic phase leads to dehydration and to transformation of bidentate to tridentate Ti-2MEHPA complexes. Ti-2MEHPA complexes are colorless

At ratios Ti/MEHPA<0·5 formation of Ti-MEHPA hydrated or solvated complex ions is suggested which form emulsion in the aqueous phase. These species slowly react with DEHPA and formation of Ti:MEHPA:DEHPA=1:1:2 complex is realized. This complex is yellow.     

Mutual Influence of Iron(III) and Gold(III) as Macroconstituents in the Extraction Systems Forming Three Liquid Phases

Abstract

The extraction of a mixture of iron(III) and goId(III) by either pure or diluted (benzene as diluent) diisopropyl ether (IPE) from aqueous solutions of hydrochloric acid at 20°C was investigated. The dependence of metal extraction on the initial concentration of hydrochloric acid, iron(III), and IPE was studied under conditions of third phase formation. It was found that under certain conditions, gold(III) coextracted with iron(IH).     

EXTRACTION OF GALLIUM/III/ FROM HYDROCHLORIC ACID BY DIISOPROPYL ETHER AND MIXTURE DIISOPROPYL ETHER-PENTANOL

In systems containing gallium (III) and hydrochloric acid, extraction with pure IPE and a mixture of IPE - pentanol was studied. The influence of the initial concentration of acid and the solvent composition as well as the temperature on the extraction of the gallium and the equilibrated phase volumes was examined. The synergistic extraction of gallium (III)was found with a mixture of IPE - pentanol and a maximum value of ΔD in a 20 %vol. of alcohol mixture. The conditions of the third liquid phase formation were found and its effect on the extraction was discussed.     

PURIFICATION OF WET PROCESS PHOSPHORIC ACID BY SOLVENT EXTRACTION WITH PROPYL ETHERS.

The distribution data for the impurities (SO⁼ ₄, F^?, Fe, Al and Mg) during purification of wet phosphoric acid (WPA) with di-n-propy1 ether (DPE), di-n-propy1 ether containing 6. 5% of the isomer n-propylriso-propyl ether (DPE(M)) and di-iso-propyl ether (DIPE) at 25°C are reported. The distribution of phosphoric acid (PA)(SO⁼ ₄, F^?, Fe, Al and Mg between the conjugated phases has been investigated. The system W-WPA-DIPE shows a three-liquid-phases-at-equilibrium zone with 65.7% of phosphoric acid in the aqueous phase, 43.9% in the heavy organic phase and 4.3% in the light organic phase. The degree of purification increases, for the three solvents studied, when decreasing the PA concentration in the organic phase (except for F^?when using DPE}. Purification data for iso-arayl alcohol (1) and these three solvents are compared, showing that di-n-propyl ether with 6.5% of the isomer propyl-iso-propyl ether is the best solvent (from all solvents investigated in these series) for the purification of the wet process phosphoric acid studied.     

Influence of Temperature on Extraction

Abstract

The literature data related to the influence of temperature on extraction are very often controversial. It appeared advisable to undertake an investigation of such an influence in systems containing diisopropyl ether (IPE), because of their ability to form three coexisting liquid phases.

In the extraction system H₂O-HC1-FeC13-IPE, the volume changes and the metal distribution depending on temperature (ranging from 13 to 40° C) and the initial concentration of hydrochloric acid (5 to 11 M) were examined. The formation of the third phase (heavy organic phase) is of special interest in the separation processes because a very high concentration of metal can be expected. The complexity of such a multi-component and multiphase system makes a phenomenological approach more appropriate than a thermodynamic one.

In the three-phase system an increase in temperature increases the distribution ratio of iron(III) whereas in the two-phase system, the distribution ratio decreases. The extraction factors based on phase volume and distribution ratio were calculated. Phase transformations occur in a narrow temperature range. A decrease of the initial acid concentration and an increase in temperature contribute to an increase in the number of equilibrated phases. Choice of the appropriate temperature in similar systems offers new possibilities in the application of extraction in separation procedures.     

THE SOLVENT EXTRACTION OF SELECTED ORGANIC COMPLEXANTS BY TRUEX PROCESS SOLVENT∗

The extraction by TRUEX solvent of ¹⁴C-labelled acetic, glycolic, and citric acids, and ¹⁴C-labelled glycine, EDTA, and ethylenediamine has been studied from aqueous solutions having different nitric acid concentrations. Only acetic and citric acids are extracted to a significant extent. Their behavior can be compared to that of oxalic acid. If the aqueous phase contains a high concentration of aluminum and iron(III) species, as in some nuclear waste solution, the extraction of aqueous complexants into the organic phase is strongly suppressed. By measuring distribution ratios of irradiated ¹⁴C-labelled acetic acid, citric acid and EDTA, it has been demonstrated that the radiolytic degradation of these compounds leads, at least in part, to oxalic acid. A scrub procedure, utilizing basic aluminum nitrate, has been successfully tested in order to remove any co-extracted oxalic acid from the TRUEX solvent.     

Extraction and separation of D/L-lactic acid in simulated fermentation broth

The recovery of lactic acid from fermentation broth plays an important part in production of lactic acid. In this case, the extraction of lactic acid from simulated fermentation broth was processed by tri-n-octylamine dissolved in oleyl alcohol. The extraction efficiency was investigated with several variables, and the optimal condition of extraction of lactic acid (10 mg mL⁻¹) from aqueous solution was tri-n-octylamine/oleyl alcohol (30/70, v/v) and solvent phase/ fermentation (1/2, v/v) stirred for 60 min under room temperature. The optimal back extraction of lactic acid was obtained by hot water (∼90 °C) with solvent phase/water (1/4, v/v). The back extracted racemic lactic acid was direct enantiomeric analyzed and separated by chiral ligand chromatography due to strict requirement of absolute configuration in pharmaceutical field and food science. The effect of various parameters on enantioselectivity was discussed and the (L)-phenylalaninamide·HCl (6.0 mmol L⁻¹) and CuSO⁴·5H₂O (3.0 mmol L⁻¹) dissolved in methanol/water (5/95, v/v) at pH=6.0 was the suitable mobile phase for chiral ligand exchange separation of (D, L)-lactic acids. By the investigations, a convenient systemic method was established for extraction and separation of (D, L)-lactic acid.     

γ‐Radiation Effects on the Performance of HCCD‐PEG for Cs and Sr Extraction

Abstract

Cobalt dicarbollide and polyethylene glycol in phenyltrifluoromethyl sulfone (HCCD/PEG in FS‐13) is currently under consideration for use in the process‐scale selective extraction of fission product cesium and strontium from acidic radioactive solutions. While the Cs and Sr solvent extraction efficiency of this formulation has been previously characterized, this solvent will be exposed to high radiation doses during use, and has not been adequately investigated for radiation stability. Here, HCCD/PEG was γ‐irradiated to various absorbed doses, to a maximum of 432 kGy, using ⁶⁰Co. Irradiations were performed for the neat organic phase, and also for the organic phase in contact with 1 M‐nitric acid mixed by air sparging. Post‐irradiation solvent extraction measurements showed that Cs distribution ratios were unaffected; however, strontium distribution ratios decreased with the absorbed dose under both conditions. The decrease in the extraction efficiency for strontium was greater when in contact with the aqueous phase. The stripping performance was not affected. A mechanism, based on reaction with the products of direct diluent radiolysis, is proposed to explain the decreases in the strontium extraction efficiency.     

A new bubbling extraction tower: Toward liquid–liquid solvent extraction at large aqueous‐to‐oil phase ratios

Enrichment and recovery of valuable components in industrial waste waters by traditional liquid–liquid solvent extraction is not economic due to extremely low concentrations of those targets. Large‐phase‐ratio extraction exhibits potential advantages for recovery of small quantities of target components from large volume of aqueous solutions. A novel bubbling extraction tower is proposed toward performing solvent extraction at large aqueous‐to‐oil phase ratios in this work. Organic extractants were covered onto surface of gas bubbles to form a layer of organic liquid membrane and the dispersed organic phase in tower could be small enough. The target components are extracted from aqueous feed solution onto the surface of the bubbles, and the enrichment ratios could be extremely high. We develop a feasible methodology to calculate tower height and operation phase ratios of the bubbling extraction tower, which is essential for future industrial scale‐up. Experimental results in pilot test are highly consistent with calculations. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3889–3897, 2015     

The Solvent Extraction of Boron with Synthesized Aliphatic 1,3‐Diols: Stripping and Extraction Behavior of Boron by 2,2,5‐Trimethyl‐1,3‐hexanediol

Abstract

A variety of aliphatic 1,3‐diols (4a–c, 5a–c, 6a–c) was synthesized from β‐hydroxy carbonyl compounds (1–3) for potential use in the solvent extraction of boron. Primary‐secondary and primary‐tertiary alcohol structures of 1,3‐diols substituted with isopropyl, isobutyl, and isopentyl groups have been demonstrated to be very efficient for the solvent extraction of boric acid from aqueous solutions. The extraction ability of 2,2,5‐trimethyl‐1,3‐hexanediol (5b) was investigated as a function of 5b concentration, solution pH, solvent properties, and stripping conditions. Extraction efficiency increased with increasing concentration of 5b, and the best extraction of boron (96.8%) was found to be at an equilibrium pH of 2 with 0.5 M of 5b. Chloroform, toluene, chlorobenzene, 2‐octanol, and n‐amyl alcohol were found to be suitable solvents for the solvent extraction of boron. The boron complex can be recovered from the organic phase by treatment with an aqueous solution of sodium hydroxide. The highest ratio (96.7%) of boron was recovered by 0.1 M of sodium hydroxide solution.     

Extraction of lactic acid into sunflower oil and its recovery into an aqueous solution

Demand for lactic acid is growing, especially, for its use in the production of biodegradable polymer (polylactate). The current method of production and separation of lactic acid is both expensive and unsustainable. This is partly due to the cost and lower efficiency of the current method for separating the lactic acid product from the fermentation media. Therefore, the development of alternative technology that will offer efficiency, economic and environmental benefits is of great importance. One of the promising technologies for recovery of lactic acid from fermentation broth is reactive liquid–liquid extraction. In this paper, processes based on reactive extraction of lactic acid into an organic phase and its recovery into an aqueous phase is examined. The percentages of extraction and recovery are determined by using a small pilot-scale microporous hollow-fibre membrane module (HFMM). Firstly, equilibrium experiments were conducted using organic solutions consisting of Aliquat 336 and trioctylamine (as carriers) and tributyl phosphate and sunflower oil (as solvents) The values of the distribution co-efficient (defined as a ratio of the concentration of lactic acid extracted over that remaining in the aqueous solution at equilibrium) were obtained as a function of feed pH (range 4.0–6.5), composition of the organic phase (ratio of carrier to solvent) and temperature (range 8–40°C). The best extraction was obtained with the organic phase of 15wt% tri-octylamine (TOA), 15% aliquat 336 dissolved in 35 wt% tri-butyl phosphate (TBP) and 35% sunflower oil. The percentage extraction from 0.1 M was approx. 70% after 4 h at pH 5.0 and at 35°C at a recirculating flow rate of 15–20 L/h. Lactic acid was reextracted from the organic phase by using 0.5 M sodium carbonate solution and approx. 90% recovery was obtained in 4 h. These results demonstrate that good extraction and recovery of lactic acid in the hollow-fibre membrane are possible. Also because of its potential for application in situ the process would allow to maintain lactic acid concentration at low levels during the fermentation and to improve productivity by suppressing the product inhibition effects.     

Extraction rates of amino acids by an emulsion liquid membrane with tri-n-octylmethylammonium chloride

The extraction rates of amino acids from alkaline aqueous solution into an emulsion liquid membrane containing tri-n-octylmethylammonium chloride as a carrier and Paranox 100 as an emulsifier were measured using a stirred transfer cell. The effects of agitation speed (0·33–0·66 rev s⁻¹), amino acid concentrations (0·5–50 mol m⁻³) and temperature (10–45°C) on the extraction rates were examined. The results were analyzed by a double-film model. The mass transfer coefficients of amino acids (0·26–1·58×10⁻⁵ m s⁻¹) and their complexes (0·60–1·72×10⁻⁵ m s⁻¹) were found to correlate well with the hydrophobicities of the amino acids. It was found that the surfactant layer influenced the mass transfer processes of both amino acids in the aqueous film and their complexes in the organic film. The permeation of amino acids with a large hydrophobicity through the emulsion liquid membrane was promoted by both high distribution and larger mass transfer rates. © 1998 Society of Chemical Industry     

Reactive Extraction of Levulinic Acid Using TPA in Toluene Solution: LSER Modeling,Kinetic and Equilibrium Studies

Abstract

Levulinic acid, a carboxylic acid containing ketone structure, is a clear to brownish semi‐solid melting at 37°C; soluble in alcohol, ether, and chloroform, levulinic acid can be used as an acidulant in foods and beverages. Organic solutions of amines are being used increasingly to separate organic acids from aqueous mixture solutions by reactive extraction. The design of an amine extraction process requires kinetic data for the acid–amine+solvent system used. Kinetic studies for the extraction of levulinic acid from aqueous solution with tripropylamine (TPA) diluted in toluene were carried out using a stirred cell for kinetic studies. Equilibria for levulinic acid extraction by TPA in toluene as a diluent have been determined. All measurements were carried out at 298.15 K. The equilibrium data were also interpreted by a proposed mechanism of complexation by which (1∶1) and (2∶1) acid‐amine complexes are formed. Kinetics of extraction of levulinic acid by TPA in toluene has also been determined. The results of the liquid‐liquid equilibrium measurements were correlated by a linear solvation energy relationship (LSER).     

Extraction of toluene,o-xylene from heptane and benzyl alcohol from toluene with aqueous cyclodextrins

The separation of aromatic compounds (toluene and o-xylene) from heptane and of benzyl alcohol from toluene with aqueous solutions of cyclodextrins has been experimentally investigated, because cyclodextrins and its derivatives can selectively incorporate several organic compounds, whereas the separation of the aqueous solution of complexed cyclodextrins from the organic feed is simple. Cyclodextrins are not soluble in organic liquids, but cyclodextrin derivatives are highly soluble in water. Hydroxypropyl-β-cyclodextrins with different degrees of substitution and methylated β-cyclodextrin were selected for the extraction of toluene and o-xylene from heptane. Hydroxypropyl-β-cyclodextrin (two different substitution degrees) and hydroxypropyl-α-cyclodextrin were selected for the extraction of benzyl alcohol from toluene. The liquid–liquid distribution experiments were carried out at room temperature. Toluene and o-xylene form 1:1 complexes with different cyclodextrins and heptane can form 1:1 to 1:3 complexes. Benzyl alcohol forms 1:3 complexes with hydroxypropylated cyclodextrins. The models developed describe the experimental data reasonably well, considering the large deviations in the analyses.Aqueous cyclodextrin solutions are not feasible for the separation of aromatic components from aliphatic hydrocarbons, due to low distribution ratios of toluene (0.05) and o-xylene (0.023) between the aqueous and organic phase. With high distribution ratios of benzyl alcohol, between 0.3 and 2.2 depending on the CD concentration (at a solvent-to-feed ratio of 1) and a benzyl alcohol/toluene selectivity of at least 100, aqueous hydroxypropylated cyclodextrin solutions have sufficient potential for extracting benzyl alcohol from toluene.     

Application of Single-Ion Activity Coefficients to Determine the Solvent Extraction Mechanism for Components of High-Level Nuclear Waste

Abstract

The TRUEX solvent extraction process is being developed to remove and concentrate transuranic (TRU) elements from high-level and TRU radioactive wastes that are currently stored at U.S. Department of Energy sites. Phosphoric acid is one of the chemical species of concern in the application of solvent extraction processes for removal of actinides, for instance at the Hanford site, where bismuth phosphate was used to recover plutonium.

The mechanism of phosphoric acid extraction with TRUEX-NPH solvent at 25°C was determined from phosphoric acid distribution ratios, which were measured by using a phosphoric acid radiotracer and a variety of aqueous phases containing different concentrations of nitric acid and nitrate. A model was developed for predicting phosphoric acid distribution ratios as a function of the thermodynamic activities of nitrate ion, and hydrogen ion. The Generic TRUEX Model (GTM) was used to calculate these activities based on the Bromley method. The derived model supports extraction by CMIO and TBP in TRUEX-NPH solvent of a phosphoric acid-nitric acid complex and a CMPO-phosphoric acid complex.     

PUBIFICATION OF WET PROCESS PHOSPHOHIC ACID BY SOLVENT EXTRACTION WITH DIBUTYL ETHER. PART. I. LIQUID-LIQUID EQUILIBRIUM OF THE SYSTEM WATER-PHOSPHORIC ACID-DIBUTYL ETHER AT 25°C.

Solubility and liquid-liquid phase equilibrium data have been determinated for the ternary system water-Phosphoric Acid-Dibutyl Ether at 25°

Data for the binodal curve have been obtained by analyzing the phosphoric acid percentage in both aqueous and organic phases. The plait point composition has been calculated by the Hand, Coolidge and Sherwood methods. The phosphoric acid extraction capacity of dibutyl ether has been compared to that of several solvents previously studied in the Alicante Chemical Engineering Division, showing that dibutyl ether has a phosphoric acid extraction capacity similar to propyl-ether and lower than isoamyl alcohol.     

The Synthesis and Characterization of New Schiff Bases and Investigating them in Solvent Extraction of Chromium and Copper

New Schiff bases containing nitrogen, sulfur and oxygen donor atoms, were designed and synthesized in a multi—step reaction sequence. The Schiff base(I) was used in solvent extraction of metal chlorides such as Cu(II) from aqueous phase to the organic phase. The influences of the parameter functions, such as pH, solvent, ionic strength of aqueous phase, aqueous to organic phase, and concentration of the extractant were investigated to shed light on their chemical extracting properties upon the extractability of metal ions. The effect of chloroform, dichloromethane, and nitrobenzene as organic solvents over the metal chlorides extraction was investigated at 25 ± 0.1°C by using flame atomic absorption and the result is that the ability of extraction in solvents as follows C₆H₅NO₂ > CHCl₃ > CH₂Cl₂.     

EXTRACTION EQUILIBRIUM OF PHENOL BY SULFURIC ACID SALTS OF TRIOCTYLAMINE

An investigation was undertaken involving the extraction equilibrium of phenol from an aqueous solution using trioctylamine sulfate salt (TOA salt)/trioctylamine (TOA) as the extractant. The purpose of using trioctylamine as the organic solvent is to increase the total capability of phenol extraction as well as to avoid the use of other organic solvents. In order to prevent the formation of a second phase from the reaction of trioctylamine and sulfuric acid, 1-octanol in an appropriate amount was added to make the organic solution homogeneous. Equilibrium distribution coefficients (K_d) in the extraction of phenol by TOA salt/TOA were measured for various operating conditions. The equilibrium distribution coefficient of phenol (K_d) between two phases decreased with increasing the initial concentration of phenol, thereby decreasing the initial concentration of sulfuric acid, and subsequently increasing the volume ratio of aqueous phase to organic phase. We recommended that the extraction is carried out at low temperature. A higher value of K_d up to 800 was obtained in using trioctylamine sulfate/trioctylamine as the extractant for equal volume ratio of aqueous phase to organic phase.     

Solid–Liquid and Solid–Liquid–Liquid Equilibria in the KI+H2O+i-C3H7OH Ternary System within 10–120°C

The solubility of components, phase equilibria, and critical phenomena in the ternary potassium iodide (KI) +water (H₂O) +isopropyl alcohol (i-C₃H₇OH) system were studied in the range of 10–120°C by the visual polythermal method. Potassium iodide was found to have a salting-out effect at temperatures above 97.0°C, and homogeneous water–isopropanol solutions were delaminated. The formation temperature of the critical tie line of the monotectic state (97.0°C) and the compositions of the solutions corresponding to the critical liquid–liquid solubility points at 104.2, 110.1, 115.6, and 120.1°C were determined. The distribution coefficients of isopropyl alcohol between the organic and aqueous phases in the monotectic state at 100.0, 110.0, and 120.0°C were calculated. The salting-out effect of potassium iodide relative to isopropyl alcohol from aqueous solution is small (the distribution coefficient K_d of isopropanol is 1.8 at 100.0°C) and slightly increases with temperature (K_d is 3.4 at 120.0°C).     

Separation of hydrocortisone and epi-hydrocortisone by solvent extraction

Solvent extraction, instead of traditional crystallization, is suggested as a new method for separation of hydrocortisone and its optical isomer, epi-hydrocortisone. The extraction behavior of alcohols, ketones, esters, ethers and chlorinated hydrocarbons was studied experimentally. For the industrial separation process it was found that the best solvents are n-butyl acetate or chloroform. The distribution coefficients of hydrocortisone and epi-hydrocortisone in an n-butyl acetate/water system at 17°C were found to be 9·98 and 2·62, respectively, and 5·57 and 1·93, respectively, in a chloroform/water system at 17°C. When n-butyl acetate or chloroform solution of crude hydrocortisone (the mixture of hydrocortisone, epi-hydrocortisone and other steroid impurities) was scrubbed by deionized water in a nine-stage cross-current at 25°C, the organic phase hydrocortisone purity increased from 78·10% to 98·22% (wt%) for the n-butyl acetate case and from 78·10% to 98·02% (wt%) for the chloroform case. The medicinal standard for hydrocortisone was attained. The effects of alcohol concentration, temperature, salting-out and pH on extraction are also discussed. ©1997 SCI