Nitric Acid Extraction into the TODGA/TBP Solvent

The tridentate diglycolamide ligand N,N,N′,N′-tetraoctyl diglycolamide (TODGA) shows many interesting properties and is a very good extractant for the minor actinides (MAs) and lanthanides but, due to its low loading capacity, requires a phase modifier when used in a solvent extraction process. Consequently, applications of TODGA in conjunction with tri-butyl phosphate (TBP) in novel DIAMEX and SANEX processes for recovering MAs have been reported. However, TODGA and TBP also extract nitric acid and this has a significant influence on process performance. Here new distribution data for the extraction of nitric acid into solvent phases containing TODGA and TBP have been collected and modeled using an equilibrium-based approach accounting for nitric acid activities in the aqueous phase. Models for the extraction of nitric acid using the individual extractants were obtained using a variety of complexes and these were then combined to give the extraction of the mixed TODGA and TBP solvent. Using this approach, the nitric acid extraction of the mixed TODGA/TBP system can be reliably reproduced indicating that no significant synergistic or antagonistic complexes are formed in solution.     

Thermal stability study of a new guanidine suppressor for the next-generation caustic-side solvent extraction process

Cesium stripping performance of thermally stressed solvent worsens slowly over time in batch tests of the Next-Generation Caustic-Side Solvent Extraction (NG-CSSX) process. NG-CSSX is currently used in full-scale equipment at the Savannah River Site for the selective removal of caesium from high-level salt waste. Recently, a new guanidine, N,N’,N”-tris(3,7-dimethyloctyl)guanidine (TiDG), was chosen for use as the suppressor, a lipophilic organic base needed for stripping, and the present study was undertaken to address the question of its stability. The NG-CSSX process solvent was evaluated for a period of three months under a variety of temperature and storage conditions. The performance of the solvent was tested at 30-day increments using an extraction, scrub, strip and extraction (ES₂S₃E) sequence. The results provide insights into the effects of storage and process conditions, the stripping behaviour of TiDG and the stability of the new solvent composition.     

Modified Diglycolamides for the An(III) + Ln(III) Co-separation: Evaluation by Solvent Extraction and Time-Resolved Laser Fluorescence Spectroscopy

The use of two recently developed diglycolamide-based extractants for the co-separation of trivalent actinides (An(III)) and lanthanides (Ln(III)) is described and compared to the well-known extractant TODGA (N,N,N’,N’-tetraoctyl diglycolamide). The addition of one or two methyl groups to the central methylene carbon atoms of the TODGA molecule leads to a reduction of the extraction efficiency for An(III) and Ln(III). This is attributed to a lower complex formation constant, which was proven by Time-Resolved Laser Fluorescence Spectroscopy (TRLFS). Conditional stability constants were determined by solvent extraction and TRLFS. The reduction in extraction efficiency leads to overall reduced distribution ratios of all tested metal ions, including Sr(II). The reduced Sr(II) extraction is beneficial as a co-extraction in a solvent extraction process could be avoided, while an efficient extraction of the desired An(III) and Ln(III) is still achieved. Furthermore, this might be a benefit, as the stripping behavior might be improved, even at moderate nitric acid concentrations. The slightly higher affinity of the diglycolamides towards Eu(III) over Am(III) is represented by all ligands, although the selectivity is rather low. This results in promising extraction properties of the modified diglycolamides towards the development of continuous solvent extraction processes.     

An Advanced TALSPEAK Concept for Separating Minor Actinides. Part 1. Process Optimization and Flowsheet Development

A solvent extraction system was developed for separating trivalent actinides from lanthanides. This “Advanced TALSPEAK” system uses 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) to extract the lanthanides into an n-dodecane-based solvent; the actinides are retained in a citrate-buffered aqueous phase by complexation to a polyaminocarboxylate ligand. Several aqueous-phase ligands were investigated, and N-(2-hydroxyethyl)ethylenediamine-N,N’,N’-triacetic acid (HEDTA) was chosen for further study. Batch distribution measurements indicate that the separation of americium (Am) from the light lanthanides increases as the pH increases. However, previous investigations indicated that the extraction rates for the heavier lanthanides decrease with increasing pH. Therefore, a balance between these competing effects is required. An aqueous phase at pH 2.6 was chosen for further process development, because this offered optimal separation. Centrifugal-contactor single-stage efficiencies were measured to characterize the system’s performance under flow conditions, and an Advanced TALSPEAK flowsheet was designed.     

Direct Selective Extraction of Actinides (III) from PUREX Raffinate using a Mixture of CyMe4BTBP and TODGA as 1-cycle SANEX Solvent

Abstract

Within the framework of our research activities related to the partitioning of spent nuclear-fuel solutions, the direct selective extraction of trivalent actinides from a simulated PUREX raffinate was studied using a mixture of CyMe₄BTBP and TODGA (1-cycle SANEX). The solvent showed a high selectivity for trivalent actinides with a high lanthanide separation factor. However, the coextraction of some fission product elements (Cu, Ni, Zr, Mo, Pd, Ag, and Cd) from a simulated PUREX raffinate was observed, with distribution ratios up to 30 (Cu). The extraction of Zr and Mo could be suppressed using oxalic acid but the use of the well-known Pd complexant N-(2-Hydroxyethyl)-ethylendiamin-N,N′,N′-triacetic acid (HEDTA) was unsuccessful. During screening experiments with different amino acids and derivatives, the sulfur-bearing amino acid L-Cysteine showed good complexation of Pd and prevented its extraction into the organic phase without influencing the extraction of the trivalent actinides Am (III) and Cm (III). The optimization studies included the influence of the L-Cysteine and HNO₃ concentration and the kinetics of the extraction. The development of a process-like extraction series showed very promising results in view of further optimizing the process. A strategy for a single-cycle process is proposed within this article.     

A Comparative Study on Response Surface Optimization of Supercritical Fluid Extraction Parameters to Obtain Portulaca Oleracea Seed Oil with Higher Bioactive Content and Antioxidant Activity Than Solvent Extraction

Portulaca oleracea (purslane) seed oil is a rich source of omega-6 and omega-3 fatty acids. Extraction of the purslane seed oil while preserving its high nutritive quality has been a challenge since conventional solvent extraction has many adverse effects on bioactive content. This study aims the optimization of purslane seed oil supercritical fluid extraction (SFE) conditions and to compare purslane seed oils obtained with SFE and conventional solvent extraction in terms of oil yield, along with the purslane seed oil quality and bioactive content. For this purpose, the SFE process parameters (pressure, temperature, static time, and dynamic time) are optimized for oil yield, omega-6, omega-3, and antioxidant activity using response surface methodology (RSM). Optimum SFE pressure, temperature, static time, and dynamic time levels are determined as 350 bar, 50 °C, 20 min, and 90 min, respectively. Oil yield and physicochemical quality properties of conventional solvent extract and SFE samples are determined and compared. Consequently, samples obtained via SFE and solvent extraction have similar quality properties. Distinctly, SFE allows an extraction with 5.6% higher total phenolic compound (TPC) and 33% higher antioxidant activity than solvent extraction. Practical Applications: In the study, the extraction of purslane oil using supercritical fluid extraction is optimized with different approaches. At optimum conditions, purslane oil is extracted and all physicochemical properties and the process efficiency (yield) are compared with the solvent-extracted samples. The results of this study make supercritical fluid extraction of purslane seed oil possible since all optimum operating conditions of a pilot-sized extractor are reported in the study. It is believed that the results provide a good starting point for industrial operations. Moreover, researchers also believe that research studies unveiling the new potential oil-bearing seeds are important to overcome the vegetable oil shortage that emerged this year.     

Comparative Evaluation of CMPO and Diglycolamide Based Solvent Systems for Actinide Partitioning in Mixer-Settler Runs Using Tracer-Spiked PHWR Simulated High Level Waste

The TRUEX solvent (0.2 M CMPO + 1.2 M TBP) was employed for countercurrent extraction studies with radiotracers spiked pressurized heavy water reactor simulated high level waste (PHWR-SHLW) employing a 12-stage of mixer-settler. The results of the mixer-settler runs with CMPO were compared with those obtained under identical conditions employing TODGA (N,N,N’,N’-tetraoctyl diglycolamide) and T2EHDGA (N,N,N’,N’-tetra-2-ethylhexyl diglycolamide) as the extractants. Even though the TRUEX solvent revealed quantitative extraction of trivalent actinides and lanthanides in 5 stages at O/A = 1, stripping of the extracted metal ions from the loaded organic phase was poor with dilute HNO₃ solution (0.2 M HNO₃). Quantitative stripping could not be achieved in 12 stages even when a complexing solution (0.1 M citric acid + 0.1 M HNO₃) was employed as the strippant. In contrast, the stripping from loaded TODGA and T2EHDGA solvents was possible in < 6 stages with 0.2 M HNO₃. The experimental results suggested that the performance of TRUEX solvent was inferior to the diglycolamide based extractants such as TODGA and T2EHDGA.     

Application of gas anti-solvent process to the recovery of andrographolide from <Emphasis Type="Italic">Andrographis paniculatanees</Emphasis>

The gas anti-solvent (GAS) process was employed to extract andrographolide, which is the active ingredient found in Andrographis Paniculatanees, using carbon dioxide as an anti-solvent. The effects of temperature, flow rate and solvent type on the extraction recovery, particle size and morphology were investigated in this study. The experiments were conducted at the temperature ranging from 25–45 °C, carbon dioxide flow rate of 1–15 mL/min, and various types of organic solvents (methanol, ethanol, acetone and N,N-dimethylformamide). The extracted product was analyzed using high performance liquid chromatography (HPLC). The highest extraction yield was found to be 1.24 g andrographolide per 100 g of A. paniculata when using acetone as a solvent, carbon dioxide flow rate of 5 mL/min and the temperature of 35 °C. It was also found that no significant change in size or morphology of the precipitates was observed when changing temperature, carbon dioxide flow rate and solvents.     

Behavior of Molybdenum (VI) in {DMDOHEMA–HDEHP/nitric acid} Liquid–Liquid Extraction Systems

The EXAm (extraction of americium) process was developed for americium recycling in future nuclear fuel cycles. In this solvent extraction system, a combination of two extractants, N,N′-dimethyl-N,N′-dioctyl-hexylethoxy malonamide (DMDOHEMA) and di-2-ethylhexyl phosphoric acid (HDEHP), in TPH (hydrogenated tetrapropylene) is used to extract americium in the first step of the process at high acidity (HNO₃ 5–6 M). Americium is co-extracted with light lanthanides and other fission products like molybdenum, iron, ruthenium, etc.. Molybdenum is selectively scrubbed during the second step at low acidity using citric or glycolic acid as a buffer and complexing agent. The speciation of Mo(VI) in aqueous solutions is highly dependent on acidity and Mo concentration. In this article, a simple thermodynamical model is proposed for Mo(VI) scrubbing based on batch extraction experiments (with pH and cation concentration variations) and stoichiometries of complexes formed in the organic phase according to electrospray ionization mass spectrometry (ESI-MS) experiments and published data on Mo(VI) speciation. At high acidity ([HNO₃] > 1 M), the MoO₂²⁺ species is strongly extracted by the solvent DMDOHEMA–HDEHP according to a solvate mechanism. At lower acidity ([HNO₃] < 1 M), cation exchange mechanisms become predominant and DMDOHEMA does not participate to the extraction Mo(VI) anymore. During Mo scrubbing at pH higher than 1, the extraction of Mo as neutral species (like MoO₃) and anionic species (like MoO₄^2–) has to be taken into account in the model to predict the “bell-shape” of Mo distribution ratio evolution as a function of pH. This model was then implemented in the PAREX simulation code developed by the CEA to build the flowsheet for the “Mo scrubbing” section of EXAm process and predict Mo concentrations profiles in batteries of mixer-settlers during pilot-scale tests.     

Ultrasonic extraction of ferulic acid from Angelica sinensis

In this paper, the extraction of ferulic acid, a pharmacologically active ingredient from the root of Angelica sinensis with ultrasonic extraction was investigated. Percolation and supercritical fluid extraction (SFE) were also employed to make comparisons with ultrasonic extraction. Three variables, which including the concentration of solvent, the ratio of solvent volume to sample (mL/g), and extraction time, were found to have great influence on ultrasonic extraction. The optimum extraction conditions were using pure ethanol with a ratio of solvent volume to sample 8:1 (mL/g) and extraction time of 30 min. Under the optimum extraction conditions, the extraction yield could reach 6.5% mass fraction, which was higher than that of SFE process with ethanol as co‐solvent and nearly a content of ferulic acid 1.0%; both the yield and the content of ferulic acid were higher than those obtained by percolation. Moreover, the time of ultrasonic extraction was significantly shortened. Overall, Ultrasonic extraction was shown to be highly efficient in the extraction of ferulic acid from Angelica sinensis.     

Solvent Extraction Separation of Trivalent Americium from Curium and the Lanthanides

The sterically constrained, macrocyclic, aqueous soluble ligand N,N′-bis[(6-carboxy-2-pyridyl)methyl]-1,10-diaza-18-crown-6 (H₂BP18C6) was investigated for separating americium from curium and all the lanthanides by solvent extraction. Pairing H₂BP18C6, which favors complexation of larger f-element cations, with acidic organophosphorus extractants that favor extraction of smaller f-element cations, such as bis-(2-ethylhexyl)phosphoric acid (HDEHP) or (2-ethylhexyl)phosphonic acid mono(2-ethylhexyl) ester (HEH[EHP]), created solvent extraction systems with good Cm/Am selectivity, excellent trans-lanthanide selectivity (K_ex,Lu/K_ex,La = 10⁸), but poor selectivity for Am against the lightest lanthanides. However, using an organic phase containing both a neutral extractant, N,N,N’,N’-tetra(2-ethylhexyl)diglycolamide (TEHDGA), and HEH[EHP] enabled rejection of the lightest lanthanides during loading of the organic phase from aqueous nitric acid, eliminating their interference in the americium stripping stages. In addition, although it is a macrocyclic ligand, H₂BP18C6 does not significantly impede the mass transfer kinetics of the HDEHP solvent extraction system.     

Studies on the Use of N,N,N´,N´-Tetra(2-ethylhexyl) Diglycolamide (TEHDGA) for Actinide Partitioning. I: Investigation on Third-Phase Formation and Extraction Behavior

Abstract

Diglycolamides have emerged as an interesting class of extractants for actinide partitioning from high-level waste (HLW). N,N,N´,N´-tetraoctyl diglycolamide (TODGA) has been extensively studied for lanthanide-actinide co-extraction behavior. The present work deals with a branched isomer of TODGA, that is, N,N,N´,N´-tetra(2-ethylhexyl) diglycolamide (TEHDGA). TEHDGA was studied for the extraction of ²⁴¹Am and third-phase formation. The effect of using different phase modifiers on the prevention of the formation of a third phase during nitric acid extraction by TEHDGA along with the acid uptake behavior by TEHDGA in the presence of the modifiers was studied. The modifiers used for this purpose were di(n-hexyl)octanamide (DHOA), isodecanol, and n-decanol. The effect of the modifiers on the uptake of ²⁴¹Am as a function of acid concentration and as a function of modifier concentration was also examined. DHOA was found to be a suitable modifier, in spite of its high acid uptake. The uptake of lanthanides Ce, La, Eu, Gd, and Nd and elements such as Fe, Ni, Mn, Mo, Ru, Sr, and Cs with DHOA-modified TEHDGA–n-dodecane solvent systems were investigated. The results obtained indicated that, while DHOA-modified TEHDGA/n-dodecane extracted lanthanides and actinides, it did not show any significant uptake of other elements. Thus, the TEHDGA-DHOA/n-dodecane solvent system can be used effectively for the partitioning of lanthanides and actinides from HLW.     

Ultrasonic extraction of ferulic acid from Ligusticum chuanxiong

The extraction of ferulic acid, a pharmacologically active ingredient from the root of Ligusticum chuanxiong, with ultrasonic extraction was investigated. Percolation and supercritical fluid extraction (SFE) were employed to make comparisons with ultrasonic extraction. Three variables, which included the concentration of solvent, the ratio of solvent volume/sample (mL/g), and extraction time, were found to have a great influence on ultrasonic extraction. The optimum extraction was with pure ethanol with a solvent volume/sample ratio 8:1 (mL/g) and extraction time of 30 min. Under the optimum extraction conditions, the extraction yield could reach 8.8% which was higher than that using SFE with ethanol as co-solvent and a content of ferulic acid of 0.7%; both the yield and the content were higher than those obtained by percolation. Ultrasonic extraction significantly shortened the time required for the extraction process. Overall, ultrasonic extraction was shown to be highly efficient in the extraction of ferulic acid from Ligusticum chuanxiong.     

Whole Cell Biotransformation of 5-(4-(2-(2-Pyridyl)methylamino)ethoxy)benzylidenethiazolidine-2,4-dione to its Benzyl Derivative Using a Yeast Reductase

Whole yeast cell reductive biotransformation of a benzylidene thiazolidinedione to its corresponding benzyl derivative has been scaled up from laboratory to small pilot plant scale. The fermentation conditions for the yeast Rhodotorula rubra were examined and cell titres increased by optimising the medium. Problems encountered in handling substrates of low water solubility are discussed. Various techniques are described for adapting the procedure for process scale operation using the general principles of process scale-up and integration. Liquid–liquid extraction using a dense solvent was performed on whole broth systems using a continuous flow liquid–liquid separator. Fatty acid impurities were removed using selective solvent extraction. © 1997 SCI.     

Parametric optimization of green synergistic reactive extraction of lactic acid using trioctylamine,Aliquat336, and butan-2-ol in sunflower oil by response surface methodology

A novel green synergistic reactive extraction technique for the removal of lactic acid (LA) from aqueous solution was explored. Response surface methodology (RSM) was applied to optimize the process variables for LA synergistic reactive extraction using a mixture of trioctylamine and Aliquat336 as extractants. During this present investigation, 2-butanol and sunflower oil were used as organic and green diluent. Systematic investigation has been carried out to obtain the optimum process conditions viz. initial LA concentration, pH of aqueous solution, extractant ratio, extractant concentration, solvent ratio, phase ratio, temperature, stirring speed, and contact time for maximizing the LA distribution coefficient (K_D) and extraction efficiency (%, η). The highest experimentally achievable LA distribution coefficient (K_D) and extraction efficiency (%) at optimized process conditions were found to be in close agreement with those predicted by numerical optimization using RSM. Thus, the results of present finding have been shown a great ability of sunflower oil as an economic and environmentally friendly green solvent for LA extraction.     

两种芳烃抽提工艺的技术对比

从溶剂性质、工艺流程、操作参数和产品质量等方面对N-甲酰基吗啉(NFM)抽提蒸馏和环丁砜液液抽提工艺进行了分析对比。结果表明:两者都是芳烃抽提的优良溶剂;NFM抽提蒸馏工艺流程简单、操作条件缓和,操作费用低;两种工艺产品质量没有本质区别。     

Combining CMPO and HEH[EHP] for Separating Trivalent Lanthanides from the Transuranic Elements

Combining octyl(phenyl)-N,N-diisobutyl-carbamoylmethylphosphine oxide (CMPO) and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) into a single process solvent for separating transuranic elements from liquid high-level waste is explored. The lanthanides and americium can be co-extracted from HNO₃ into 0.2 mol/L CMPO + 1.0 mol/L HEH[EHP] in n-dodecane. The extraction is relatively insensitive to the HNO₃ concentration within 0.1–5 mol/L HNO₃. Americium can be selectively stripped from the CMPO/HEH[EHP] solvent into a citrate-buffered N-(2-hydroxyethyl)ethylenediaminetriacetic acid solution. Separation factors >14 can be achieved in the range pH 2.5–3.7, and the separation factors are relatively insensitive to pH—a major advantage of this solvent formulation.     

Modeling the Kinetics of Antioxidant Extraction from Origanum vulgare and Brassica nigra

In the present research work, the effect of solvents, particle size, solvent/solid ratio, and temperature on the extraction efficiency of oregano (Origanum vulgare) and mustard (Brassica nigra) were investigated. The extraction process proceeded at a fast rate followed by a slower one. Particle size, solvent type, solvent/solid ratio and temperature had a positive effect on the extraction process, and maximum extraction was achieved by ethanol. Extraction kinetics was determined with a mathematical model derived from Fick's second law. The results were verified with Fick's diffusion model for extraction kinetics in all experiments, which provided the initial rate and extent of solid–liquid extraction. Antioxidant values were determined using 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and 2, 2′-azino-Bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS). The extracts of O. vulgare and B. nigra prepared using ethanol showed optimal antioxidant activity.     

Kariya (Hildegardia barteri) seed oil extraction: comparative evaluation of solvents,modeling, and optimization techniques

In this work, the effects of solid/solvent ratio (0.10–0.25?g/ml), extraction time (3–8?h), and solvent type (n-hexane, ethyl acetate, and acetone) together with their shared interactions on Kariya seed oil (KSO) yield were investigated. The oil extraction process was modeled via response surface methodology (RSM), artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) while the optimization of the three input variables essential to the oil extraction process was carried out by genetic algorithm (GA) and RSM methods. The low mean relative percent deviation (MRPD) of 0.94–4.69% and high coefficient of determination (R²) > 0.98 for the models developed demonstrate that they describe the solvent extraction process with high accuracy in this order: ANFIS, ANN, and RSM. The best operating condition (solid/solvent ratio of 0.1?g/ml, extraction time of 8?h, and acetone as solvent of extraction) that gave the highest KSO yield (32.52?wt.%) was obtained using GA-ANFIS and GA-ANN. Solvent extraction efficiency evaluation showed that ethyl acetate, n-hexane, and acetone gave maximum experimental oil yields of 19.20?±?0.28, 25.11?±?0.01, and 32.33?±?0.04?wt.%, respectively. Properties of the KSO varied based on the type of solvent used. The results of this work showed that KSO could function as raw material in both food and chemical industries.     

The nondistillation alcohol extraction process for soybean oil

Summary A new vegetable oil extraction process has been developed, with alcohol as the oil solvent. The process requiresno distillation to recover the oil or the solvent characteristics of the alcohol. This has been demonstrated by reuse of the solvent more than 85 times. The theoretical energy requirement of the process is about three-fourths that of the hexane process. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.