Influence of Some Organic Additives on the Extractive Separation of Americium(III) by Sulfoxides

Abstract

The solvent extraction behavior of americium(III) from aqueous nitrate media by two long-chain aliphatic sulfoxides has been examined systematically in the presence of several water-miscible organic solvents to study their possible synergistic effect on metal ion extraction. Methanol, ethanol, n- and isopropanol, n-butanol, dioxane, acetone, as well as acetonitrile, were employed as the organic component of the mixed (polar) phase. These additives affected the extraction to varying degrees. Extractability of Am increased 5 to 10-fold with increasing concentration of some of these additives, with the maximum enhancement being observed in the presence of acetone or acetonitrile. However, alcohols are generally very poor in this respect. Possible reasons for such behavior are briefly discussed. The distribution of several common contaminants was also investigated at the optimum condition for americium extraction.     

Extraction Equilibria of Butyric Acid with Organic Solvents

Abstract

Fourteen solvents (five with a tertiary amine and different diluents, four C8-C18 alcohols, dibutylether, two hydrocarbons, and two vegetable oils) have been tested for the extraction of butyric acid. The highest distribution coefficient for butyric acid is shown by solvents with tertiary amines. A ternary solvent with amine extractant, n-alkanes as diluent, and higher alcohol as modifier can be advantageous in this procedure. Amines enable the extraction of acid at a pH above the pK _a value up to about pH 5.6. With an increase of the molecular weight of alcohol, the value of the distribution coefficient decreases. Its value for pure alcohols is independent of the concentration of acid in the aqueous phase. Equilibrium data suggest that the stoichiometry of the acid-alcohol complex is 2:1, and only undissociated acid is extracted.     

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.     

Reactive Extraction of Formic Acid by using Tri Octyl Amine (TOA)

Abstract

Distribution of formic acid (methanoic acid) between water and tri octyl amine (TOA) dissolved in various alcohols (isoamyl alcohol, hexan-1-ol, octan-1-ol, nonan-1-ol, decan-1-ol) as diluents, as well as the extraction capacity of pure diluent alone have been studied at isothermal conditions. All measurements were carried out at 298.15 K. The difference between the physical extraction and reactive extraction was studied. The loading factor, T _T, extraction efficiency, D _E, modified separation factor, S _F, and, distribution coefficients, K _D were calculated. The isoamylalcohol was found most effective solvent with maximum distribution value of 14.521. Possible equilibrium complexation constants for (acid:amine) (5:1), (6:1), and (7:1) have been determined as values of about 21.8 × 10³, 15.6 × 10⁴, and 11.1 × 10⁵ for K₅₁, K₆₁, and K₇₁, respectively with isoamylalcohol. Furthermore, Linear Solvation Energy Relationship (LSER) model equation has been obtained to calculate distribution coefficients for alcohols with regression coefficient of 0.981.     

Effect of Possible Interferences on the Extraction of 1-Butanol from Aqueous Solution by the Ethyl Esters of Soybean Oil Fatty Acids

Abstract

The methyl, ethyl, propyl and butyl esters of vegetable and tree oils are effective solvent extractants for 1-butanol from aqueous solution. Early applications of this process will probably involve bacterial mixed solvent fermentations of relatively impure waste and low-valued carbohydrates. Two types of materials, salts and solvents, could be expected to affect the extraction of 1-butanol from such industrial fermentation systems. The effect of four salts, three alcohols, and a ketone were evaluated using factorial experiments. Variations in NaCl, Na₂SO₄, Na₂SO₃, and KHPO₄ from 0 to 0.15 M on the extraction of 0.1 to 4.1% 1-butanol from aqueous solutions at 25,40, and 55 C gave small changes in distribution coefficient. Mild increases occurred with increasing teperature and increasing NaCl, Na₂SO₄, and KH₂PO₄. Mild decreases in 1-butanol extraction occurred with increasing Na₂SO₃. Variations in acetone, ethanol, and 2-propanol concentrations ranging between 0 and 4% w/v at 25, 40 and 55 C gave small changes in distribution coefficient at 1-butanol concentrations ranging between 0.1 and 4.1% w/v had little effect. A slight increase in 1-butanol extraction was observed with increasing 1-pentanol under similar conditions.     

Separation of NaOH by Solvent Extraction Using Weak Hydroxy Acids

Abstract

Separation of sodium hydroxide from aqueous salt solutions at elevated pH may be accomplished by use of solvent extraction with weak hydroxy acids. A series of lipophilic weak hydroxy acids, including alkyl phenols and fluorinated alcohols, has been characterized with regard to their ability to extract sodium into 1‐octanol as a function of temperature and extractant concentration. Isotherms are presented at 10, 25, and 60°C, employing extractant concentrations up to 1 M and aqueous NaOH concentrations up to 7 M. Near stoichiometric loading of all compounds tested may be achieved in a process postulated to be simple cation exchange. Extraction strength increases with the expected acidity of the hydroxy acids. Strongest extraction was observed with two alkyl phenols and 4‐n‐octyl‐α,α‐bis(trifluoromethyl)benzyl alcohol. Essentially complete removal of free hydroxide from a solution containing sodium hydroxide, nitrate, and aluminate was accomplished using 1 M 4‐tert‐octylphenol in 1‐octanol at 60°C. Consequently, as the pH of the solution was lowered, aluminum was observed to precipitate as the Bayerite form of Al(OH)₃. Contacting the loaded solvent with water released NaOH into the strip solution, and good selectivity for hydroxide vs. nitrate and aluminate was obtained. Since hydroxide equivalents rather than the hydroxide ion itself are believed to be extracted by the weak hydroxy acids, the process is referred to as pseudo‐hydroxide extraction. Application of this concept to sodium removal and caustic recycle in the treatment of alkaline nuclear waste appears feasible.     

Prediction of Optimum Composition of the Mixed Solvent N-Methylpyrrolidone/Ethylene Glycol for the Extraction of Aromatics

Abstract

The optimum composition of mixed solvent which is usually determined experimentally is predicted by a method in which the minimum total energy required for extraction and subsequent solvent recovery by distillation is calculated. The method is demonstrated using N-methylpyrrolidone (NMP) and monoethylene glycol (EG) as mixed solvent for the extraction of benzene from a hexane/benzene mixture. UNIFAC method was used to predict liquid phase equilibria in extraction and liquid-vapor equilibria in distillation. To demonstrate the method flexibility, ethylene glycol was replaced by water as another alternative solvent, and the optimum composition of the new mixed solvent of NMP/water was predicted. However this particular mixed solvent required much higher energy than NMP/EG case.     

Development of Effective Solvent Modifiers for the Solvent Extraction of Cesium from Alkaline High‐Level Tank Waste

Abstract

A series of novel alkylphenoxy fluorinated alcohols were prepared and investigated for their effectiveness as modifiers in solvents containing calix[4]arene‐bis‐(tert‐octylbenzo)‐crown‐6 for the extraction of cesium from alkaline nitrate media. The structure of the fluorinated portion of the modifier influences the chemical stability, and a modifier that contained a terminal 1,1,2,2‐tetrafluoroethoxy group was found to decompose following long‐term exposure to warm alkaline solutions. However, replacement of the tetrafluoroethoxy group with a 2,2,3,3‐tetrafluoropropoxy group led to a series of modifiers that possessed the alkaline stability required for a solvent extraction process. Within this series of modifiers, the structure of the alkyl substituent (tert‐octyl, tert‐butyl, tert‐amyl, and sec‐butyl) of the alkylphenoxy moiety was found to have a profound impact on the phase behavior of the solvent in liquid–liquid contacting experiments, and hence on the overall suitability of the modifier for a solvent extraction process. The sec‐butyl derivative [1‐(2,2,3,3‐tetrafluoropropoxy)‐3‐(4‐sec‐butylphenoxy)‐2‐propanol] (Cs‐7SB) was found to possess the best overall balance of properties with respect to third phase and coalescence behavior, cleanup following degradation, resistance to solids formation, and cesium distribution behavior. Accordingly, this modifier was selected for use as a component of the solvent employed in the Caustic‐Side Solvent Extraction (CSSX) process designed for the removal of cesium from high‐level nuclear waste (HLW) at the U.S. Department of Energy's (DOE) Savannah River Site. In batch equilibrium experiments, this solvent has also been successfully shown to extract cesium from both simulated and actual solutions generated from caustic leaching of HLW tank sludge stored in tank B‐110 at the DOE's Hanford Site.     

LIQUID-LIQUID EQUILIBRIUM OF THE WATER-PHOSPHORIC ACID-3-PENTANONE SYSTEM AT 25°C. A COMPARATIVE STUDY OF THE EXTRACTION POWER OF DIFFERENT SOLVENTS

Abstract

Solubility and liquid-liquid phase equilibrium data have been determined for the Water-Phosphoric Acid-3-Pentanone ternary system at 25 °C. Tie lines have been obtained and the plait point composition calculated. The phosphoric acid extraction capability of 3-Pentanone has been compared to that of other solvents previously studied. A systematic approach to the effects of chain length, functional group, branching and cyclation on the extraction power of the different solvents reported in the literature shows that the compatibility between solvent and phosphoric acid is higher for alcohols followed by ketones, esters and ethers. Branching and cyclation lead to a higher solubility of the acid into the organic phase, while an increase in the chain length results in a wider heterogeneous zone (i.e. in a decreasing solubility).     

Optimization of microwave-assisted extraction of bioactive compounds from pistachio (Pistacia vera L.) hull

ABSTRACT

Phenolic compounds were extracted from pistachio hull using microwave-assisted solvent extraction (MASE). The effects of four parameters, microwave power, extraction time, solvent to sample ratio, and ethanol concentration were evaluated. The extraction conditions were optimized by response surface methodology to enhance the total phenolic content (TPC). Optimal conditions were found as 140 W microwave power, 4.5 min extraction time, 19:1 (v/w) solvent to sample ratio, and 56% ethanol concentration to get maximum TPC (62.24 mg GAE/g dry hull). Also, MASE was compared with conventional solvent extraction (CSE) and MASE gave higher TPC, yield, and antioxidant activity.     

General Model for Aggregation of Metal-extractant Complexes in Acidic Organophosphorus Solvent Extraction Systems

Abstract

The physicochemical nature of the metal-extractant aggregates formed in the organic phase of acidic organophosphorus solvent extraction systems was investigated to further understand hydrometallurgical extraction. The experimental techniques of fluorescence, FT-IR, and NMR spectroscopy, static and dynamic light-scattering, tensiometry, as well as classical physicochemical methods and extraction measurements, were employed to clarify the nature of the molecular aggregates associated with the extraction of Ca²⁺, Co²⁺, Ni²⁺, and Zn²⁺ by di(2-ethylhexyl)phosphoric acid (HDEHP) in n-alkane diluents. Significantly, there appears to be three regimes of aggregation behavior in solvent extraction systems consistent with the mechanism suggested earlier by Neuman and co-workers [Colloids Surfaces, 46, 45 (1990)]. A simplified model is proposed herein for the aggregation of metal-extractant complexes in acidic organophosphorus solvent extraction systems: as the concentration of metal-extractant complexes increases, the initial metal-extractant complexes or nuclei grow in size via a stepwise polymerization mechanism to form linear aggregates that eventually undergo a structural reorganization to form cyclic aggregates or reversed micelles which, in turn, are capable of further growth. Furthermore, the role of reversed micelles and other association microstructures in solvent extraction is briefly addressed. Although the model seems to be fairly general and provides a unifying interpretation of the species formed in the organic phase of solvent extraction systems, complexities in practical extraction systems must be considered for a detailed understanding of the solvent extraction mechanism.     

Optimization of Microwave‐Assisted Extraction of Flavonoid from Radix Astragali using Response Surface Methodology

Abstract

Response surface methodology (RSM) was applied to predict optimum conditions for microwave‐assisted extraction (MAE) of flavonoid from Radix Astragali. A central composite design was used to monitor the effect of temperature, extraction time, solvent‐to‐material ratio, and the ethanol concentration on yield of total flavanoid (TFA). Optimum extraction conditions were predicted as 108.2°C, 26.7 min, 23.1 ml/g solvent‐to‐material ratio and 86.2% ethanol. The maximum yield 1.234±0.031 mg/g was close to the yield of Soxhlet and higher than that of ultrasound assisted extraction and heat reflux extraction. MAE was an effective alternative to conventional extraction methods.     

涡轮萃取塔在林可霉素萃取中的应用研究

林可霉素是一种高效广谱抗生素,有着广泛的应用。目前在工业生产中,大多采用多级混合澄清槽从发酵液中萃取林可霉素,但混合澄清槽存在占地面积大、溶剂储存量大、操作费用高,操作环境差等问题。涡轮萃取塔是一种高效的萃取塔,有着占地面积小、溶剂储存量低、萃取效率高等优点。在直径50 mm小型涡轮萃取塔中对林可霉素进行了研究:在不同相比、不同转数条件下,研究了林可霉素的传质情况及液滴直径大小分布特征。实验结果表明:在相同流量的情况下,随着转速增高,分散相滞留率随之增高,林可霉素的萃取效果越好。在相同转速、轻相流量不变的情况下,重相流量越低,林可霉素的萃取效果越好。研究结果表明:涡轮萃取塔用于林可霉素的萃取是可行的。     

Coalescence Extraction: A Novel,Rapid Means of Performing Solvent Extractions

Abstract

We report the development of a novel solvent extraction technique which exploits the coalescence properties exhibited by some solvent combinations at elevated temperatures. The technique allows for instantaneous mixing which approaches the theoretical extraction limit. In the extraction of Pb²⁺ from aqueous solution into either 2,4-pentanedione or glutaronitrile containing dicyclohexano-18-crown-6 (DC18C6), extraction times were reduced from 2 hours to less than 1 minute. The K _ex value for extracting Pb²⁺ into glutaronitrile with DC18C6 as the extractant was determined to be 260. The novel coalescence extraction technique is compared to traditional systems in terms of extraction efficiency, speed of extraction, and feasibility of practical applications.     

Predispersed Solvent Extraction

Abstract

A novel method for solvent extraction from aqueous solution dispenses with a mixer-settler as the solvent is precomminuted in the form of aphrons which, after extraction, are buoyed to the surface by micrometer-sized bubbles. Extraction from solutions as dilute as a few parts per billion is possible in seconds.     

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.     

HYDROMETALLURGY OF STRATEGIC METALS

ABSTRACT

This paper gives a short overview of the importance of solvent extraction in the production and recycling of strategic metals. Both the present situation and possible developments are considered. The use of solvent extraction in the processing of powdered metal-containing materials with tailor-made characteristics is also discussed as it is attracting increasing attention.     

Numerical Simulation of Uranium Extraction from Nitric Acid Medium Using Hollow-Fiber Contactor

ABSTRACT

A two-dimensional axisymmetric computational fluid dynamics (CFD) model is presented to simulate uranium extraction from nitric acid medium using tri-n-butyl phosphate in n-dodecane in a hollow-fiber membrane contactor operated in non-dispersive solvent extraction mode. CFD model solves continuity and momentum-transport equations for the feed and shell sides and species transport equations for the feed side, shell side, as well as the membrane. Complex boundary conditions of flux continuity and concentration jump are implemented in the CFD model. The estimates of percentage of uranium extraction obtained from CFD simulations for different parametric conditions are compared with the experimental results, and a good agreement is observed. The validated CFD model is used to gain detailed insights into the hydrodynamics and mass transfer.

Abbreviations CFD: Computational fluid dynamics; NDSX: Non-dispersive solvent extraction; TBP: Tri n-butyl phosphate     

PURIFICATION OF HYDROCHLORIC ACID BY ISOOCTANE EXTRACTION

ABSTRACT

Removal of organic compounds from hydrocloric acid can be performed by a solvent extraction process followed by a solvent regeneration step by adsorption with sepiolite. The extraction study includes the analysis of the influence of the operating conditions, the determination of the solute distribution coefficient for isooctane and the effect of temperature on the extraction. The adsorption isotherms were calculated to check the technical viability of the method. The obtained efficiency of extraction is close to 90 wt%, whereas that of the solvent regeneration recovery is over 67 wt%     

Centrifugal Contactors for Laboratory-Scale Solvent Extraction Tests

Abstract

A 2-cm contactor (minicontactor) was developed and used at Argonne National Laboratory for laboratory-scale testing of solvent extraction flowsheets. This new contactor requires only 1 L of simulated waste feed, which is significantly less than the 10 L required for the 4-cm unit that had previously been used. In addition, the volume requirements for the other aqueous and organic feeds are reduced correspondingly. This paper (1) discusses the design of the minicontactor, (2) describes results from having applied the minicontactor to testing various solvent extraction flowsheets, and (3) compares the minicontactor with the 4-cm contactor as a device for testing solvent extraction flowsheets on a laboratory scale.