Kinetics Of Solvent Extraction Research Articles

Kinetics of ultrasound-assisted solvent extraction of vanadium with methyltrioctylammonium chloride (MAC)

The ultrasound-assisted extraction process of vanadium from the aqueous phase to the organic phase by methyltrioctylammonium chloride (MAC) was studied. The factors that influence the vanadium extraction rate such as stirring speed, temperature, and ultrasound power were investigated. The rate expression of vanadium extraction with ultrasound was established. The extraction process could consist of diffusion and chemical capturing steps at the aqueous-organic interface. This study demonstrated that the diffusion resistance could be eliminated by increasing the stirring speed and ultrasound power. The vanadium extraction process without diffusion resistance conformed to the first-order kinetic model. The activation energy (Ea) of this extraction process was determined as 36.7 kJ mol−1 along with a pre-exponential factor k0a as 3.27 × 105 s−1, while the ultrasound enhancement factor can be expressed as ε = 1 + 1.40 × 10−2P - 6.61 × 10−5P2. The optimal extraction kinetics are identified by examining the factors affecting the vanadium extraction rate (rextr), which are stirring speed ≥ 200 rpm, ultrasound power (P) = 90 W, extraction temperature (T) = 318.15 K. This study provides a theoretical basis for the extraction process of vanadium and aids the design of ultrasound-assisted extraction applications.

Kinetic study of uranium (VI) extraction with tributyl-phosphate in a stratified flow microchannel

Solvent extraction kinetics are of considerable importance in process and apparatus design, especially when the mass transfer is coupled with a chemical reaction. In such circumstances, the mass transfer can either be diffusion limited, reaction limited, or both in a mixed regime. Conventional extraction techniques lead to acquire an overall mass transfer coefficient for fast chemical systems. The latter brings together diffusional and reactional parts that are difficult to distinguish independently. This problem is addressed using a high velocity parallel flow microfluidic setup for the investigation of the extraction kinetics of the fast chemical system U(VI):HNO3/TBP:TPH. Experimental data were analyzed using a combination of overall mass transfer resistance calculations and advection–diffusion-reaction models. Results indicate that a chemically limited regime was obtained at a high initial concentration (119 g.l−1) of uranium (VI) due to Marangoni convections. Whereas, for low initial concentrations (10–30 g.l−1) and short residence times in the microchannel (≤13 ms), both diffusion and reaction impact the transfer rate. The obtained value of the apparent rate constant under current operating conditions ([HNO3] = 3 M, % TBP = 30 % (v/v)) was of (6.5 ± 1.7) × 10−4 m.s−1. This value is much higher than what conventional extraction techniques predicted, indicating the better mass transfer efficiency in the microfluidic setup due to the decrease of the diffusional limitation.

Isothermal kinetics of ethanolic extraction of total hypericin from pre-extracted Hypericum perforatum flowers.

Hypericum perforatum L., Hypericaceae (St John's wort) is a highly familiar plant in the medicinal community which recently showed good antiviral activities including against some types of coronavirus. Establishing the kinetics of isothermal extraction of total hypericin (TH) from the pre-extracted flowers of H. perforatum flowers. The solvent extraction of TH from the remaining solid residue after the pre-extraction procedure was performed providing isothermal conditions at the temperature of 313K, 323K, and 328K (±1K) using ethanol as a solvent. The feasibility of mathematical modelling of the isothermal kinetics of TH extraction was explored applying some of the frequently used kinetic models of solvent extraction: first-order reaction model, film theory model, unsteady-state diffusion model, parabolic diffusion model, Elovich's equation. The kinetic complexity was examined using the differential isoconversional method. The kinetics of isothermal solvent extraction of TH is a kinetic elementary process with the unique rate-determining step. It was found that the kinetics of isothermal extraction of TH can be best described employing the theoretical Jander three-dimensional (3D) diffusional model and its suitability for modelling the investigated extraction was confirmed with statistical parameters [adjusted linear correlation coefficient (R2 adj )=0.998-0.999 and the standard error (SE)=0.005-0.006]. The values of the model kinetic parameters (rate constant (kM /min-1 ), activation energy (Ea =21.0±4.9kJ/mol) and pre-exponential factor (lnA=3.1±2.2min-1 ) were calculated. Based on the model mechanism of the kinetics of the investigated extraction a new mathematical model is suggested and the controlling step of the overall process was found.

Kinetics of solvent extraction of zirconium from acidic raffinate using tributyl phosphate

ABSTRACT Kinetics of solvent extraction of zirconium, from raffinate generated in zirconium purification plant, have been studied, using tributyl phosphate as the extractant solvent. The system being a liquid-liquid dispersive system, it is chemical reaction kinetics controlled. The order of reaction, pre-exponential factor, and activation energy were determined. It was estimated that the extraction of zirconium and the co-extraction of nitric acid have an activation energy of 38.02 kJ/mole and 5.7 kJ/mole, respectively. Predictions of the distribution coefficient of zirconium between the organic and aqueous phases were made through the determined rate constants. Kinetics was also studied in terms of activity.

Optimization and kinetics of ultrasound-assisted solvent extraction of gamma oryzanol from dried rice bran soapstock

Optimization and kinetics of ultrasound-assisted solvent extraction of gamma oryzanol from dried rice bran soapstock

Optimization and kinetics of ultrasound-assisted solvent extraction of gamma oryzanol from dried rice bran soapstock

Optimization and kinetics of ultrasound-assisted solvent extraction of gamma oryzanol from dried rice bran soapstock

Kinetics of Oil Extraction from Candlenut (Aleurites moluccana)

Oil from candlenut (Aleurites moluccana) was extracted using a solvent extraction technique. The influence of three parameters namely extraction time, extraction temperature as well as liquid to solid (L/S) ratio on the candlenut oil yield were studied to optimise the extraction conditions for achieving maximum oil yield. The maximum candlenut oil yield (35.67%) was achieved using methanol as a solvent at a temperature of 45oC for 80 min of extraction period. The optimum L/S ratio was 10ml/g. It was found that the candlenut oil yield increases with the increase of extraction time, extraction temperature and L/S ratio. Kinetics of solvent extraction of oil from candlenut was evaluated using Peleg’s model and Logarithmic model. The model parameters were calculated using the experimental data. The kinetics of candlenut oil extraction conforms very well to the Peleg’s model with a high R2 value of 0.9927 and low MRPD value of 1.827%. However, the Logarithmic model can fairly describe the candlenut oil extraction process with the values of R2 and MRPD of 0.9653 and 4.352%, respectively.

A study of cerium extraction kinetics by TODGA in acidified and non-acidified organic solvent phases in the context of fission product management

In the context of management of the waste streams arising from the reprocessing of spent nuclear fuel, studies have been conducted into the solvent extraction kinetics of lanthanide fission products by the oxygen-donor ligand N,N,N’,N’-tetraoctyl diglycolamide (TODGA) and the effects of solvent phase acidity on the effectiveness of this organic extractant molecule. In this study, we observe a reduction in the rate of cerium extraction as solvent phase acidity increases, attributed to aggregation of the extractant. The effect is shown to be reversible through neutralization while a permanent prevention method is the subject of further work.

First Evidence of Solvent Spillage under Subcritical Conditions in Aerogel Production

The first evidence of solvent spillage under subcritical conditions during aerogel production is presented. The main objective was to understand the underlying phenomena controlling the solvent extraction kinetics during autoclave pressurization. Alginate, silica, and polyurethane as gels and ethanol, methyl ethyl ketone, and ethanol/water as solvents were investigated. When CO2 diffuses in the gel solvent, there is a volume expansion of the liquid solvent. This expanded liquid mixture spills out of the gel and accumulates as a separate liquid phase at the bottom of the autoclave. A lag time was observed between the start of the autoclave pressurization and the moment in which liquid starts to accumulate in the autoclave. The time needed for the solvent to start accumulating at the bottom of the autoclave is controlled by capillary forces and the saturation of the CO2-gas phase, on which temperature has an important effect. Low operating temperature and thereby low solubility of the solvent in the gas phase is suggested as the factor that enhances the kinetics of solvent removal at subcritical conditions.

Solvent extraction kinetics of Ag(I) with methyl ketonic p-tert-octylcalix[4]arene in the modified Lewis cell technique

The solvent extraction kinetics of Ag(I) with methyl ketonic p-tert-octylcalix[4]arene as a hydrophobic extractant have been studied using a modified Lewis cell system. The effects of different parameters affecting the extraction efficiency such as the stirring speed, the temperature, and the Ag concentration were all investigated. The initial Ag(I) extraction efficiency was found to rapidly increase on increasing the stirring speed in the Lewis cell to 170 rpm after which a plateau in the efficiency occurred. That is, Ag(I) extraction was influenced by diffusion up to 170 rpm, with the diffusion contribution being minimized over 170 rpm. Thus, for the cell configuration employed, 170 rpm represents the crossover point between diffusion and chemical reaction control at the liquid–liquid interface. The results are thus in accord with the efficiency of Ag(I) extraction by methyl ketonic p-tert-octylcalix[4]arene being governed by a mixed regime (diffusion and chemical reaction) for the liquid–liquid extraction system investigated. Furthermore, study of the thermodynamic parameters indicated that the adsorption process was spontaneous and exothermic in nature. Overall, using a modified Lewis cell system it has been possible to identify the factors influencing the efficiency of extraction under different conditions for the above liquid–liquid extraction system.

Solvent extraction kinetics of Sm(III), Eu(III) and Gd(III) with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester

Abstract Solvent extraction kinetics of Sm (III), Eu (III) and Gd (III) from hydrochloric acid have been focused on using 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (P507) with Anordning for Kontinuerlig Undersokning av Fordelningsfaktore vid Vatske Extraction (AKUFVE). Compared with the conventional set-up, some advantages emerge obviously, for example, fast phase separation, easy operation and convenience of kinetic data acquisition. First of all, the extraction mechanism was discussed based on the dimeric model of P507. Secondly, the effects of stirring speed were investigated and 420 r·min− 1 was determined of the following experiments. The effects of pH, concentration of rare earth elements (REEs) and P507 on the extraction rate were analyzed. The results indicated that the extraction mechanism changed with the increasing concentration of P507. Then, the experiments with different temperature were carried out. It turned out that the values of apparent activation energy (Ea) for Sm(III), Eu(III) and Gd(III) extracted by P507 were 26.80 kJ·mol− 1, 13.40 kJ·mol− 1 and 11.10 kJ·mol− 1 respectively, the resistance of the entire process was limited by diffusion or both of diffusion and reaction. Finally, the correlation equations were obtained, and the theoretical results fit with the experimental data well, most relative error was within ± 30%.

The Effects of Nitric Acid on Extraction Properties of TODGA During Fission Product Management

ABSTRACTIn the context of management of the wastes arising from the reprocessing of spent nuclear fuel, studies have been conducted into the solvent extraction kinetics of lanthanide fission products by TODGA and the effects of solvent phase acidity on the effectiveness of this organic extractant molecule. In this study we observe an increase in organic phase viscosity increasing acidity and, potentially by consequence, that the rate of cerium extraction is summarily decreased.

High Precision Droplet-Based Microfluidic Determination of Americium(III) and Lanthanide(III) Solvent Extraction Separation Kinetics

A new method for studying solvent extraction kinetics has been applied for measuring americium and lanthanide extraction rate constants. This droplet-based microfluidic method uses commercially available components and provides rapid, high throughput and accurate determination of absolute interfacial mass transfer rate constants. Reported for the first time are americium extraction rates relevant to TALSPEAK-type process conditions, including the americium and lanthanide rate dependencies on pH and extractant power.

Zinc Extraction Kinetics Studies in the Lewis Cell Based on Conductivity Measurements

In the current study, a novel procedure for studying the zinc solvent extraction kinetics in the Lewis cell is presented. In this study, three steps were followed. In the first step, using the response surface methodology (RSM), the conductivity relation as a function of the pH and the zinc concentration was found. With respect to this model, knowing the pH and the conductivity of a zinc solution, the zinc concentration of the solution is obtained. In the next step, with respect to the RSM design of the experiment, an optimum condition, in which the high extraction of zinc occurred in the Lewis cell, was found to be the pH of 2.88 and the initial zinc concentration of 14.96 g/L. In the final step, the kinetic study was carried out on the solution with the aforementioned condition. Taking into account the mathematical kinetic models obtained by the Lewis cell, the extraction of zinc(II) from a zinc sulfate solution with D2EHPA was limited both by the diffusional and chemical regimes.

Kinetic modeling of pressure-assisted solvent extraction of polyphenols from green tea in comparison with the conventional extraction

In the study, the kinetics of pressure-assisted solvent extraction (PSE) of polyphenols from green tea at different pressures (300, 400, 500MPa) was studied. The model derived from Patricelli, which describes the two step extraction consisting of rapid washing followed by slow diffusion, had been applied to estimate the extraction kinetics. The model parameters were calculated using the experimental results obtained from PSE and conventional solvent extraction (CSE). The results showed a good prediction of Patricelli’s model for extraction kinetics in all experiments (R2⩾0.996), which gave the possibility for estimation of the extraction rate and extent of PSE. The results also showed that the extraction by washing was more efficient with PSE than CSE. In addition, the initial extraction rate of the PSE was always much larger than that of the CSE. Therefore, PSE was more effective for extracting the green tea polyphenols than the CSE.

Impact of instant controlled pressure drop pre-treatment on solvent extraction of edible oil from rapeseed seeds

The fundamental analysis and modeling of kinetics of solvent extraction of rapeseed oil enable the quantification of the “washing” and “diffusion” steps. Both are illustrated through “starting accessibility” and “effective diffusivity”, respectively. This is a relevant way to identify how to intensify and optimize the operating conditions in terms of highest yield and lowest extraction time. Using the instant controlled pressure drop (DIC) expansion as a pre-treatment for the intensification of the whole unit operation, the starting accessibility ratio reached a value of 28.69% against 19.03% for the raw material. Effective diffusivity of DIC treated samples reached a value of 2.05 × 10-12 m2 /s instead of 0.72 × 10-12 m2 /s for the raw material. Regarding oil composition, predominant fatty acids in all extracted rapeseed oils are oleic acid (C18:1 n9) ranged from 57.58 to 59.03%, linoleic acid (C18:2 n6) ranged from 21.23 to 21.89%, and linolenic acid (C18:3 n3) ranged from 9.11 to 9.45%. None of DIC treatment produced a significant variation in relative fatty acid profile.

Instant Controlled Pressure Drop technology: From a new fundamental approach of instantaneous transitory thermodynamics to large industrial applications on high performance–high controlled quality unit operations

Abstract Solvent extraction processes have been largely used in various industries. They recently were improved through new physical concepts such as CO2 Supercritical Fluid Extraction, Ultrasound assisted process, Microwave-assisted extraction, Instant Controlled Pressure Drop DIC-assisted extraction… Systematically, a pretreatment stage of grinding takes place in order to improve the exchange surface increasing the starting accessibility. Swelling of the material structure implies an increase of the porosity thus leading to higher solvent diffusivity within the solid matrix. A new concept of expanded granule powder has recently been defined using Instant Controlled Pressure Drop DIC technology. Whatever the type of solvent is (even CO2-SFE), such a swelled structure dramatically intensifies the kinetics through a higher specific exchange surface thanks to the open pores, while improving the solution solvent–solute diffusivity within the solid. Coupled to ultrasound, the internal transfer of solute within the pore solvent can likewise be intensified by replacing molecular diffusion within the pores by an effective convection transfer. In this work, we carried out a first approach of modeling of solvent extraction kinetics of expanded granules involving higher exchange surface and greater internal diffusion process.

An Integrated UV-Vis Microfluidic Device for the Study of Concentrated Solvent Extraction Reactions

A custom built microfluidic device that potentially enables real time monitoring of solute transfer across a water/oil interface is presented and discussed. The device consisted of a Pyrex ® glass, Y-Y shaped microchannel fabricated with an inbuilt UV-Vis detection system. The device was connected to a spectrograph by means of optical fibres for detection of the signal. The device was tested against both a blue coloured dye (waxoline blue) and the metallorganic complex of Co(II) and di (2-ethylhexyl) phosphoric acid (DEHPA). Due to the very short optical path length (~ 10 -4 cm), in situ measurements of highly concentrated analytes are shown to be possible. The use of the device for measurements of concentrated solvent extraction kinetics is envisaged.

From BTBPs to BTPhens: The Effect of Ligand Pre-Organization on the Extraction Properties of Quadridentate Bis-Triazine Ligands

The synthesis, lanthanide complexation and solvent extraction of An(III) and Ln(III) radiotracers from nitric acid solutions by a pre-organized, phenanthroline-derived bis-triazine ligand CyMe4-BTPhen are described. It was found that the ligand separated Am(III) and Cm(III) from the lanthanides with remarkably high efficiency, high selectivity, and faster extraction kinetics compared to its 2,2’-bipyridine counterpart CyMe4-BTBP. The origins of the ligands extraction properties were established by a combination of solvent extraction experiments, X-ray crystallography, kinetics and surface tension measurements and lanthanide NMR spectroscopy.

Toward Mechanistic Understanding of Nuclear Reprocessing Chemistries by Quantifying Lanthanide Solvent Extraction Kinetics via Microfluidics with Constant Interfacial Area and Rapid Mixing

The closing of the nuclear fuel cycle is an unsolved problem of great importance. Separating radionuclides produced in a nuclear reactor is useful both for the storage of nuclear waste and for recycling of nuclear fuel. These separations can be performed by designing appropriate chelation chemistries and liquid-liquid extraction schemes, such as in the TALSPEAK process (Trivalent Actinide-Lanthanide Separation by Phosphorus reagent Extraction from Aqueous Komplexes). However, there are no approved methods for the industrial scale reprocessing of civilian nuclear fuel in the United States. One bottleneck in the design of next-generation solvent extraction-based nuclear fuel reprocessing schemes is a lack of interfacial mass transfer rate constants obtained under well-controlled conditions for lanthanide and actinide ligand complexes; such rate constants are a prerequisite for mechanistic understanding of the extraction chemistries involved and are of great assistance in the design of new chemistries. In addition, rate constants obtained under conditions of known interfacial area have immediate, practical utility in models required for the scaling-up of laboratory-scale demonstrations to industrial-scale solutions. Existing experimental techniques for determining these rate constants suffer from two key drawbacks: either slow mixing or unknown interfacial area. The volume of waste produced by traditional methods is an additional, practical concern in experiments involving radioactive elements, both from disposal cost and experimenter safety standpoints. In this paper, we test a plug-based microfluidic system that uses flowing plugs (droplets) in microfluidic channels to determine absolute interfacial mass transfer rate constants under conditions of both rapid mixing and controlled interfacial area. We utilize this system to determine, for the first time, the rate constants for interfacial transfer of all lanthanides, minus promethium, plus yttrium, under TALSPEAK process conditions, as a first step toward testing the molecular mechanism of this separation process.