Separation of Quercentin by Pre-dispersed Solvent Extraction

Pre-dispersed solvent extraction (PDSE) was used to extract quercentin from its diluted solution. The influences of temperature, phase volume ratio (PVR), concentration of sodium Dodecyl benzene sulphonate and pH value etc. on the extraction efficiency were examined. It is found that, compared with traditional extraction techniques under the same condition, a higher extraction productivity can be obtained by PDSE. The stability of colloidal liquid aphrons plays an important role in this process. In a certain scope, the extraction efficiency increases with PVR. Excessive amount of solvent is not much helpful. A new analytical method by using ultraviolet spectrometer to determine the concentration of quercentin is established.     

Selective Actinide Extraction with a Tri‐Synergistic Mixture Using a Centrifugal Contactor Battery

Abstract

The reprocessing of spent nuclear fuels produces a quantity of high‐level liquid waste (HLLW), which is subsequentely vitrified. The most important contributors to the long‐term radiotoxicity of the vitrified HLLW are the so‐called minor actinides (MAs), which are neptunium, americium, and curium. This paper presents the results obtained during some extraction tests of americium(III) in a synthetic liquid waste representative of that coming from the PUREX and DIAMEX processes, obtained by dissolving the respective nitrate salts of the lanthanides(III) in a diluted solution of nitric acid and spiked with ²⁴¹Am and ¹⁵²Eu. The extraction process employed a tri‐synergistic organic extractant mixture and a centrifugal contactor battery of eight stages.     

Demonstration of a TODGA‐Based Continuous Counter‐Current Extraction Process for the Partitioning of Actinides from a Simulated PUREX Raffinate,Part II: Centrifugal Contactor Runs

Abstract

The efficiency of the partitioning of trivalent actinides from a PUREX raffinate is demonstrated with a TODGA+TBP extractant mixture dissolved in an industrial aliphatic solvent TPH. Based on the results of cold and hot batch extraction studies and with the aid of computer code calculations, a continuous counter‐current process is developed and two flowsheets are tested using miniature centrifugal contactors. The feed solution used is a synthetic PUREX raffinate, spiked with ²⁴¹Am, ²⁴⁴Cm, ²⁵²Cf, ¹⁵²Eu, and ¹³⁴Cs. More than 99.9% of the trivalent actinides and lanthanides are extracted and back‐extracted and very high decontamination factors are obtained for most fission products. The co‐extraction of zirconium, molybdenum, and palladium is prevented using oxalic acid and HEDTA. However, 10% of ruthenium is extracted and only 3% is back‐extracted using diluted nitric acid. The experimental steady‐state concentration profiles of important solutes are determined and compared with model calculations and good agreement is generally obtained.     

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.     

Recovery of Chloroform from Effluent with Solvent Extraction–Distillation Process

Abstract

A solvent extraction–distillation process for recovery of chloroform in aqueous effluent was developed. Sutfonated kerosene was used for extraction of chloroform. When the flow ratio of organic phase to aqueous phase is 0.1, the chloroform concentration in the aqueous effluent can be decreased from 10 g/L to about 100 mg/L by 3-stage countercurrent extraction. The distribution ratio of chloroform between sulfonated kerosene and water is about 50. Sodium sulfate in the aqueous effluent will enhance the distribution. A small amount of water was added to the distillation column for stripping chloroform in sulfonated kerosene. RPC was used as a commercial extractor. Scale-up from the data of the pilot test was based on the Karr correlation. Recovery of chloroform was over 90%, and residual kerosene in the aqueous effluent from the extraction was lower than 70 mg/L. It is expected that the technique can be used for the recovery of other organic solvents miscible with kerosene.     

Modelling of the Extraction and Back‐Extraction Equilibria of Zinc from Spent Pickling Solutions

Abstract

This work reports the study of the chemical equilibria of the extraction and back‐extraction of zinc from spent pickling solutions. Tributyl phosphate was used as a selective extractant and service water as a back extraction agent. Feed solutions had an average composition of 6.4 M Cl^?, 1.2 M Zn⁺², 1.7 M Fe⁺² and traces of other heavy metals i.e., Pb, Ni, Cu, Mn. Under the experimental conditions the ion ZnCl₄ ^2? was the predominant zinc species in feed. A careful experimental design was performed obtaining the equilibria mathematical models and parameters, K_EX=0.137 (mol/L)^?4, and K_BEX=1.46 [?].     

Downstream Processing of Lactic Acid by Membrane-Based Solvent Extraction∗

Abstract

Lactic acid has extensive use in the food and chemical industry. About half the lactic acid used in the world is produced by fermentation of carbohydrates using lactic acid bacteria. The recovery of lactic acid from the fermentation broth is more difficult than the fermentation itself. In the present work a study of membrane-based solvent extraction as a separation unit for the continuous downstream processing of lactic acid from fermentation broth was carried out. The experiments were performed using simulated fermentation broths made of lactic acid in acetate buffer or distilled water as the feed solution. The effects of membrane material, organic carrier, and pH of the feed solution on membrane extraction efficiency were investigated. A separation degree of 35% was obtained by using a polyether-etherketone (PEEK-WC 14%) membrane with 5% trioctylamine as the organic carrier in n-heptane. The experimental results obtained with the simulated system encourage the use of membrane-based solvent extraction with a real fermentation broth.

     

Modification and Evaluation of Non‐Polar Sorbents for Solid‐Phase Extraction

Abstract

Modification of packings for solid‐phase extraction through high‐frequency low‐temperature plasma treatment is a new method to obtain a wide variety of sorbents. This method is still in the process of investigation and application. In this study, several commercial sorbents have been modified in high‐frequency low‐temperature plasma with the mixed hydrogen/benzene system. The solvation parameter model is used to characterize the sorption properties of commercially available and plasma treated sorbents for solid‐phase extraction. Chromatographic test mixtures from the literature were used to probe hydrophobicity, free silanol interactions and shape selectivity of the sorbents. The physical and retention properties of the plasma treated sorbents indicate their suitability to be used in solid‐phase extraction. Some suggestions concerning the possible practical application of the newly obtained sorbents have been made.     

Separation of Zinc Ions from an Acidic Mine Drainage using a Stirred Transfer Cell–Type Emulsion Liquid Membrane Contactor

Abstract

This is a report on the separation and recovery of zinc ions from an acidic mine drainage using a stirred transfer cell‐type emulsion liquid membrane contactor. Di(2‐ethylhexyl) phosphoric acid was used as a highly selective carrier for the transport of zinc ions through the emulsified liquid membrane. A study was made of the effect on the extraction extent and initial extraction rate of the following variables: pH and initial metal concentration of the feed phase, carrier content in the organic solution, a stripping agent concentration in the receiving phase, and stirring speed in the transfer cell. The content of sulfuric acid as a stripping agent did not show in the studied range any significant influence on metal permeation through the SLM, although a minimum hydrogen ion concentration of 100 g/L is suggested in the internal aqueous solution to ensure an acidity gradient between both aqueous phases to promote the permeation of metal ions toward the strip liquor. Results show that using a pH of 4.0 in the feed acid solution, a concentration of 3% w/w_o of phosphoric carrier in the organic phase and a H₂SO₄ content of 100 g/L in the strip liquor, the extent and rate of extraction through the liquid membrane can be highly favored, pointing to the potential of this method for extracting heavy metals from many kinds of dilute aqueous solutions.     

Synergistic Solvent Extraction and Separation of Lanthanide(III) Ions with 4‐Benzoyl‐3‐Phenyl‐5‐Isoxazolone and the Quaternary Ammonium Salt

The solvent extraction of the lanthanide(III) ions (without Pm) with a 4‐benzoyl‐3‐phenyl‐5‐isoxazolone(HPBI) alone and in the presence of the quaternary ammonium salt Aliquat 336 in perchlorate form (QClO₄) in C₆H₆ was investigated by the slope analysis method. The composition of the extracted species was determined as Ln(PBI)₃ and Q[Ln(PBI)₄] (Q⁺ is the quaternary ammonium salt cation). The values of the equilibrium constant were calculated. Synergistic effects were found for all lanthanide metals when they were extracted with a binary mixture of HPBI and QClO₄. The influence of the synergistic agent on the extraction process has been discussed. The parameters of the extraction process were determined. The separation factors between adjacent metals were evaluated.     

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.     

Investigation into the Extraction–Chromatographic Separation of a Binary Mixture in a Series of Multistage Columns

Theoretical Foundations of Chemical Engineering - The semibatch multistage extraction chromatographic separation of a binary system of components has been experimentally studied under various...     

Non‐Isothermal Non‐Adiabatic Dehydrogenation of Cyclohexane in Catalytic Membrane Reactors

Abstract

This study focuses on modeling and analysis of the non‐isothermal, non‐adiabatic, dehydrogenation of cyclohexane in membrane catalytic reactors. The dehydrogenation reaction is endothermic with a low equilibrium conversion of 0.06 at a temperature of 473 K and pressure of 101 kPa. The membrane reactor removes hydrogen from the reaction mixture and results in increase of the reaction conversion. The analysis is made as a function of feed flow rate, feed temperature, feed composition, inert flow rate in the feed stream, flow rate of sweep gas, pressures of the tube side and shell side, permeability constant of hydrogen, and tube diameter. The analysis also includes a study of the co‐current and the counter‐current flow modes. The results show lower conversion for the counter‐current flow mode, because of the decrease in the driving force for permeation. A comparison of model predictions against previous literature studies shows good agreement.     

Pseudo‐Hydroxide Extraction in the Separation of Sodium Hydroxide from Aqueous Solutions Using Alkyl Phenols

Abstract

Pseudo‐hydroxide extraction of sodium hydroxide from aqueous solution using four alkyl phenols of nearly identical molecular weight in 1‐octanol at 25°C was examined to understand the effect of alkyl substituents. The order of extraction strength among the four alkyl phenols tested was 4‐tert‐octylphenol>3,5‐di‐tert‐butylphenol>2,4‐di‐tert‐butylphenol>2,6‐di‐tert‐butyl‐4‐methylphenol. A good correlation with phenol pK _a was observed, indicating that extraction strength is determined by phenol acidity, as modified by steric effects in proximity to the phenol –OH group. The effective partition ratios (P _eff) of two phenols from 1 M NaOH solution were determined, showing that the phenols remain predominantly in the 1‐octanol phase even when converted to their sodium salts. However, the hydrophobicity of the tested phenols may not be sufficient for process purposes. The equilibrium constants for the governing extraction equilibria were determined by modeling the data using the program SXLSQI, supporting the cation‐exchange extraction mechanism. The proposed mechanism consists of two simple sets of equilibria for

1. Ion‐pair extraction to give Na⁺OH^? ion pairs and corresponding free ions in 1‐octanol the phase and

2. Cation exchange by monomeric phenol molecules (HAs) to form monomeric organic‐phase Na⁺A^? ion pairs and corresponding free organic‐phase ions.

Analysis of the Processes of Extraction–Chromatographic Separation in a Cascade of Mixing–Settling Extractors

Theoretical Foundations of Chemical Engineering - An analysis of the processes of extraction separation of a mixture of components in a cascade of mixing–settling extractors operating in the...     

Experimental Verification of Caustic‐Side Solvent Extraction for Removal of Cesium from Tank Waste

Abstract

A caustic‐side solvent extraction (CSSX) process was developed to remove Cs from Savannah River Site (SRS) high‐level waste. The CSSX process was verified in a series of flowsheet tests at Argonne National Laboratory (ANL) in a minicontactor (2‐cm centrifugal contactor) using simulant. The CSSX solvent, which was developed at Oak Ridge National Laboratory (ORNL), consists of a calixarene‐crown ether as the extractant, an alkyl aryl polyether as the modifier, trioctylamine as the suppressant, and Isopar®L as the diluent. For Cs removal from the SRS tank waste, the key process goals are that: (1) Cs is removed from the waste with a decontamination factor greater than 40,000 and (2) the recovered Cs is concentrated by a factor of 15 in dilute nitric acid. In the flowsheet verification tests, the objectives were to: (1) prove that these process goals could be met; (2) demonstrate that they could be maintained over a period of several days as the CSSX solvent is recycled; and (3) verify that the process goals could still be met after the solvent composition was adjusted. The change in composition eliminated the possibility that the calixarene‐crown ether could precipitate from the solvent. The process goals were met for each of the verification tests. The results of these tests, which are summarized here, show that the CSSX process is a very effective way to remove Cs from caustic‐side waste.     

Third Phase Formation in the Extraction of Inorganic Acids by TBP in n‐Octane

Abstract

The extraction of HNO₃, HClO₄, H₂SO₄ and H₃PO₄ by 20% (v/v) TBP (0.73 M) in n‐octane was measured under identical conditions up to and beyond the critical point of third phase formation (Limiting Organic Concentration, or LOC condition). The data, together with those obtained previously for HCl, allowed us to establish the following lyotropic series of effectiveness with respect to third phase formation in the extraction of acids by TBP: HClO₄>H₂SO₄>HCl>H₃PO₄>HNO₃. This series correlates with the amount of water present into the organic phase at the point of phase splitting. This result reinforces the validity of the reverse micellar model developed previously for the extraction of metal salts by TBP. The measurements of LOC values as a function of temperature revealed major differences among the acid‐TBP systems investigated. For HClO₄, the strong increase of the LOC value with increasing temperatures is accompanied by a large favorable entropy change. The opposite is true for HCl, while H₂SO₄ and H₃PO₄ represent intermediate cases. Measurements of the LOC values for the extraction of HClO₄ by TBP dissolved in a series of diluents confirmed that topological parameters, such as the Connectivity Index, CI, are useful for predicting the critical condition for phase splitting in different diluents. Based on the linear correlation between LOC values for HClO₄ and CI values of diluents, the effective Connectivity Index of the French nuclear reprocessing diluent, HTP, a complex mixture of highly branched alkanes, was determined.     

Alternatives to Nitric Acid Stripping in the Caustic‐Side Solvent Extraction (CSSX) Process for Cesium Removal from Alkaline High‐Level Waste

Effective alternatives to nitric acid stripping in the Caustic‐Side Solvent Extraction (CSSX) solvent have been demonstrated in this work. The CSSX solvent employs calix[4]arene‐bis(tert‐octylbenzo‐18‐crown‐6) (BOBCalixC6) as the cesium extractant in a modified alkane diluent for decontamination of alkaline high‐level wastes, such as those found at the Savannah River and Hanford sites. Results reported in this paper support the idea that replacement of the nitrate anion by a much more hydrophilic anion like borate can substantially lower cesium distribution ratios on stripping. Without any other change in the CSSX flowsheet, however, the use of a boric acid stripping solution in place of the 1 mM nitric acid solution used in the CSSX process marginally, though perhaps still usefully, improves stripping. The less‐than‐expected improvement was explained by the carryover of nitrate from scrubbing into stripping. Accordingly, more effective stripping is obtained after a scrub of the solvent with 0.1 M sodium hydroxide. Functional alternatives to boric acid include sodium bicarbonate or cesium hydroxide as strip solutions. Profound stripping improvement is achieved when trioctylamine, one of the components of the CSSX solvent, is replaced with a commercial guanidine reagent (LIX^® 79). The more basic guanidine affords greater latitude in the selection of aqueous conditions in that it becomes protonated even at mildly alkaline pH values. Under process‐relevant conditions, cesium distribution ratios on stripping are approximately 100‐fold lower compared with the current CSSX performance. The tolerance to surfactants is good, and the extraction properties of the solvent remain unchanged over three successive extract‐scrub‐strip cycles. From the point of view of compatibility with downstream processing, boric acid represents an attractive stripping agent, as it is also a potentially ideal feed for borosilicate vitrification of the separated ¹³⁷Cs product stream. The possibilities for use of these results toward a dramatically better next‐generation CSSX process, possibly one employing the more soluble cesium extractant calix[4]arene‐bis(2‐ethylhexylbenzo‐18‐crown‐6) (BEHBCalixC6) are discussed.     

Solvent Extraction of Lanthanides(III) with N‐Cinnamoyl‐N‐phenylhydroxylamine and Its Trifluoromethyl Derivative

Abstract

N‐m‐Trifluoromethylcinnamoyl‐N‐phenylhydroxylamine (CF₃‐CPHA) was synthesized. The acid‐dissociation constant and distribution constant between chloroform and water of CF₃‐CPHA and N‐cinnamoyl‐N‐phenylhydroxylamine (CPHA), which was the mother compound of CF₃‐CPHA, were determined spectrophotometrically. The extraction behavior of tervalent lanthanides (Ln), Pr, Eu, and Yb into chloroform solution containing CPHA or CF₃‐CPHA was studied. They are extracted as self‐adduct chelates, LnL₃(HL)₃, where L and HL denote the ligand anion and neutral ligand, respectively. The extraction constants and separation factors for the lanthanides with CPHA and CF₃‐CPHA were evaluated. The extraction constant with CPHA are smaller than that obtained with CF₃‐CPHA. However, it is observed that CPHA possesses higher selectivity than CF₃‐CPHA.     

Separation of Diacteone Alcohol‐Water Mixtures by Membrane Pervaporation

Abstract

A study was conducted to evaluate membrane pervaporation for the separation of diacetone alcohol‐water mixtures using commercially available membranes for organic enrichment and dehydration. Empirical correlations for the effect of the process parameters of feed concentration, feed temperature, permeate‐side pressure, and scale‐up were developed. The solvent‐water mixture was successfully separated with a poly(vinyl alcohol) based Sulzer PERVAP 2210 dehydration membrane. Various dehydration membranes were evaluated and a comparison of the flux and separation factor was made. The membrane performance in separating acetone‐water mixtures was also studied. An overall model to predict the membrane area needed for a scale‐up was developed based on the results.