Batch Extraction Experiments Research Articles

Surrogates for Liquid-Liquid Extraction.

Fuel surrogates are mixtures that mimic the properties of real fuels with only a small number of components, simplifying the calculation and simulation of fuel-related processes. This work extends a previously published surrogate optimization algorithm toward the generation of fuel surrogates with a focus on liquid-liquid extraction characteristics. For this purpose, experimental liquid-liquid equilibrium data from batch extraction experiments are incorporated into the calculation procedure as an additional constraint. The use of the method is demonstrated by optimizing a surrogate for the catalytic reformate. Application of the surrogate to an extraction process and comparison with experimental data demonstrate that the resulting surrogate accurately depicts the properties of the real mixture with regard to liquid-liquid extraction performance. This demonstrates that the use of such surrogates is of particular interest for mixtures used as extracting agents for biofuels.

Trace-scale extraction of carrier-free tungsten radioisotope as a homolog of Sg using ionic liquid from acid solutions: Kinetic study

This study aimed to find a rapid extraction system for the preparation of a Seaborgium (Sg) aqueous chemistry experiment in the future. A new approach for extraction of 181W tracer as a lighter homolog of (Sg) by ionic liquids is explored. A natural tantalum target was activated by a beam of 9 MeV proton at Cologne University to produce carrier-free 181W. The preliminary batch extraction experiments of the carrier-free 181W from HCl and H2SO4 solutions have been evaluated. Different batch extraction parameters such as feed acidity, diluent type, ionic strength (KCl feed) and reducing agent as a function of time were explored. The obtained results demonstrated that the highest distribution of carrier-free 181W from 0.001 M acidic solutions using the used ionic liquid is observed. A significant rapid kinetic for the extraction of trace-scale using the used ionic liquid is achieved within 5 sec. The preliminary results are necessary to design the upcoming aqueous experiments of Sg. The next goal will be on-line experiments with the centrifuge system SISAK to develop the aqueous chemistry extraction of Sg using the most promising and adequate experimental setup.

Stabilization of As and Heavy Metal-Contaminated Soils by Two Mine Drainage-Treated Sludges

This study explored and analyzed the potential of the practical use of acid mine drainage-treated sludge (AMDS) as a new soil stabilizer for arsenic (As) and heavy metals. Various analyses, toxicity evaluations, and extraction batch experiments were performed to investigate the characteristics of the AMDS as a soil stabilizer and to identify the main mechanisms to fix As and heavy metals on the AMDS in soil. Two types of AMDS, copper metal mine drainage-treated sludge (MMDS) and coal mine drainage-treated sludge (CMDS) and four contaminated soils with different pollution scenarios were used in the experiments. ‘Soil A’ and ‘Soil D’ were mainly contaminated with Cd, Pb and Zn. ‘Soil B’ and ‘Soil C’ were contaminated with As. Results from XRD, XRF, SEM-EDS, TG-DTA, and BET analyses suggested that AMDS is mainly composed of Fe- and Ca- bearing minerals such as CaCO3, Ca(OH)2 and amorphous Fe-oxide (hydroxide), which have a large surface area and high adsorption capacity for As and heavy metals. From batch extraction experiments, the Pb stabilization efficiency of both of the AMDSs in soil A, which has a high Pb and Zn content, was higher than 90%. The high heavy metal stabilization efficiency comes directly from the electrostatic attraction between metal cations and the negatively charged AMDS surface and/or from the co-precipitation of metal oxide (hydroxide) and CaCO3, which occurs comprehensively on the AMDS surface. In the case of Zn, the stabilization efficiency in soil A was somewhat low due to the adsorption competition with Pb, but the Zn stabilization efficiency of the CMDS in soil A was higher than 80% (70% or higher for the MMDS). For soil D, the Zn stabilization efficiency of two AMDSs was higher than 85% because of the lower concentration of other heavy metals in soil D, compared to in soil A. The As stabilization efficiency of the AMDSs in soil contaminated with As (soil B and soil C) was higher than 85%, (mostly > 95%). The overall stabilization efficiency of two AMDSs for heavy metals and As were higher than 75% and 85% (mostly > 90%), respectively, regardless of soil type. We concluded that this high As stabilization efficiency was due to the formation of a new complex by ligand exchange between the Fe- (oxide) hydroxide and the arsenate and also to the cation bridge effect between the AMDS surface and the arsenate as well as the co-precipitation.

Remediation of arsenic-containing ferrihydrite in soil using iron- and sulfate-reducing bacteria: Implications for microbially-assisted clean technology

The iron-reducing bacterium (IRB) Shewanella oneidensis MR-1 and a sulfate-reducing bacterium (SRB) Desulfovibrio vlugaris miyazaki, were used in varying sequences for batch and column arsenic extraction experiments to assess their use in alleviating arsenic pollution from arsenic-containing ferrihydrite in soil. Both batch (four conditions) and column experiments show variations in biological sequence affect the arsenic release and species. The results of arsenic release from batch conditions are: IRB-SRB (2.28 mg/g) > SRB-IRB (1.72 mg/g) > SRB+IRB (0.55 mg/g) > Control group (pure water, 0.04 mg/g). Further cycle operations from batch experiments showed that IRB-SRB operation always obtained the best performance of releasing arsenic. The column experiments achieved greater arsenic release: SRB+IRB (10.87 mg/g) > IRB-SRB (7.54 mg/g) > SRB-IRB (6.48 mg/g) relative to arsenic in the pristine samples (36.6 mg/g). Flow methods could obtain more releasing performance than batch experiment. The hydraulic conductivity in the column experiments was best in the SRB-IRB operation (average water difference: 0.39 psi for SRB-IRB, 0.86 psi for IRB-SRB and 1.07 psi for SRB+IRB). After the biological operation, chemical treatment (0.5 M, (NH4)2HPO4) only desorbed 11.14–39.81% of the total arsenic quantity of each operation. Reductive dissolution is the main driving reason for arsenic release, though the formation of FeS was found to hinder arsenic release. Analysis of the solids showed that the SRB+IRB operation results in 58.07% arsenic released. These results suggest that microbially-assisted reduction using iron- and sulfate-reducing bacteria may be an effective technology for remediating arsenic-bearing soil e.g. paddy soil using systems such as an in-situ injection and pump.

Batch and Column Extraction of Lead from Al-Doura Oil Refinery Soil

The aim of this research is to investigate the extraction of lead (Pb) from soil of Al-Doura oil refinery in Baghdad/Iraq. Ethylenediaminetetraacetic acid disodium salt (Na2EDTA) and Hydrochloric acid (HCl) solution were used as extractants. Soil washing method was practiced in two ways, batch extraction and column extraction experiments. A set of batch experiments were carried out at different conditions of extractant (Na2EDTA, HCl) concentration, contact time, pH and agitation speed. From the batch experiments, the maximum removal percentages of Pb that have been obtained were 70 % using Na2EDTA (0.1M) at pH 4 , agitation speed 200 and at equilibrium time 4 hours and 65 % using HCl (1M) at pH 1.08 , agitation speed 200 at equilibrium time 5 hours. 
 Column experiments were conducted at different conditions of extractant (Na2EDTA, HCl) concentration, contact time and flow rate. The maximum removal percentages of Pb were 78% using Na2EDTA (0.1M) at pH 4 , flow rate 30 ml/hr and equilibrium time 8 hours and 75% using HCl (1M) at pH 1.08, flow rate 20 ml/hr and equilibrium time 10 hours. 
 The column extraction proved that the extractant volume required to achieve high removal efficiency is less than that of the batch extraction, but requires a longer contact time.
 The experimental data of batch and column extraction were applied in four kinetic models; first order, parabolic diffusion, two constant and Elovich model to find best fit model for extraction system. For batch extraction, the parabolic diffusion and two-constant models gave the best correlation {coefficient of determination (R2)} with experimental data using HCl and Na2EDTA respectively. While for column extraction, Elovich model gave good correlation with experimental data.

Improving the Robustness of Trivalent Actinides/Lanthanides Separation by Bis(2,4,4-trimethylpentyl)dithiophosphinic Acid: Batch Extraction and Process Demonstration

ABSTRACT Separation studies during the past decades have demonstrated that ligands with “soft” donor atoms (e.g., N and S, relative to O) show greater affinity to An(III) over Ln(III) in solvent extraction. Among these ligands for An(III)/Ln(III) separation, bis(2,4,4-trimethylpentyl) dithiophosphinic acid (HBTMPDTP), the active component of the commercially available Cyanex 301 product, has been found to exhibit exceptionally high selectivity for An(III) over Ln(III). However, effective Ln(III)/An(III) separation in this system can only be achieved under relatively high and narrow pH conditions, thus requiring accurate control of the acidity during the extraction. To cope with this problem, in this work we deliberately select formic acid as a buffer reagent to control and stabilize the pH for An(III)/Ln(III) separation by HBTMPDTP. Both batch extraction and process demonstration experiments were conducted to verify the applicability of the proposed extraction system. In particular, the process testing on 14-stage centrifugal contactors with simulated waste confirms that the pH can be well stabilized, and meanwhile high An(III)/Ln(III) separation factors are maintained. Decontamination factors of Am(III) from Ln(III) as high as 50,000 were achieved. This work has successfully demonstrated the efficiency of An(III)/Ln(III) separation and the robustness of operation in the modified system.

Chitosan-based ion-imprinted polymer for selective extraction of Zn(II) in aqueous samples

ABSTRACT In this study, a new strategy for novel chitosan-based ion-imprinted polymer (IIP) preparation was adopted for selective separation and recovery of Zn(II) ions from aqueous environmental samples using batch extraction experiments. The Zn(II) ion-imprinted polymer was prepared by precipitation copolymerisation of methacrylamide and 2,2- azobisisobutyronitrile along with Zn(II) ions and toluene as a functional complexing monomer, initiator, template ion, and porogenic solvent, respectively, in the presence of chitosan. The ethylene glycol dimethacrylate and tetraethyl orthosilicate were used as cross-linking agents. The prepared Zn(II) ion-imprinted polymer was characterised by Fourier transform infrared spectroscopy, field emission scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis, and inductively coupled plasma-optical emission spectroscopy to determine the structural and functional IIP variations before and after Zn(II) adsorption. Characterisation results suggested the formation of Zn(II) ion-imprinted polymer with excellent thermal stability and also have the potential for selective Zn(II) extraction. Further, the Zn(II) sorption using IIP sorbent was also evaluated as a function of pH, IIP sorbent dosages, Zn(II) ion concentration, sorption time, and IIP sorbent reusability. The Zn(II) sorption equilibrium was studied using various isotherm and kinetic models, and the result suggested that the Langmuir and pseudo-second-order model as the best to explain the sorption process. Sorption capacity was calculated using Langmuir isotherm linear equation and its value was found to be 3.06 mg/g. The method detection limit (MDL) and limit of quantification (LOQ) of sorbent were calculated as 0.1 and 0.3 mg/L, respectively. Finally, the developed sorbent Zn(II) IIP was found to be effective in the selective extraction of Zn(II) from the tap and river water samples.

Rational design and synthesis of magnetic covalent organic frameworks for controlling the selectivity and enhancing the extraction efficiency of polycyclic aromatic hydrocarbons.

A series of three-dimensional magnetic covalent organic frameworks were designed and synthesized via monomer selection, coating thickness optimization, and composite strategy transformation. Their structure properties including morphology, functional group, surface area, and pore size were characterized. The relationship between the structural properties and analytical performance was systematically investigated by density functional theory calculation and batch extraction experiments for polycyclic aromatic hydrocarbons. It is proven that the extractant modified by monomer 1,4-phthalaldehyde provides a hizgh affinity for high molecule weight polycyclic aromatic hydrocarbons and the right balance between extraction and elution efficiency. The relationship between coating thickness and mass transfer rate of polycyclic aromatic hydrocarbons was studied by accurate tuning of coating layers via layer-by-layer method. A mathematical model was derived and employed to determine that two coating layers were sufficient to provide the highest extraction efficiency with the shortest equilibrium time. The extractants synthesized by two different composite strategies (layer-by-layer and one-step) show opposite selectivity for polycyclic aromatic hydrocarbons. After optimization of theextraction conditions, dispersed solid-phase extraction coupled with gas chromatography-mass spectroscopy method was developed providing a wide linear range (5-500ngL-1), good linearity (R2 > 0.9923), high precision in intra-day (RSD% < 8.2%) and inter-day (RSD% < 12.3%) detection, and low detection limits (1.5-15.1ngL-1). The method was applied to thesimultaneous determination of 16 polycyclic aromatic hydrocarbons with acceptable recoveries, which were 87-109% for groundwater, 83-116% for East Lake water, and 82-116% for Yangtze River water samples.

Optimization of parameters for the extraction of Pb from lateritic soil using EDTA

In this study, we optimized the factors influencing the remediation of Pb-contaminated laterite soil by Ethylenediamenetetraacetic acid (EDTA) washing technology. Soil was artificially contaminated with Pb and laboratory extractions were carried out by varying (1) pH of EDTA, (2) EDTA–Pb molar ratio, (3) Solution–soil ratio and (4) the number of steps in the sequential extraction process. The batch extraction experiments were designed using central composite design (CCD)-based response surface methodology by varying these four factors at five different levels. The range adopted for these factors were; pH (4–8), EDTA–Pb molar ratio (0–4), Solution–soil ratio (3–21) and number of steps of extraction (1–5). The significance and adequacy of the model given by CCD were tested using analysis of variance (ANOVA). Numerical optimization results showed that the maximum extraction efficiency of 90.82% is obtained at a desirability of 0.97 when pH of EDTA was 4, EDTA–Pb molar ratio was 3, solution–soil ratio was 16.5 and the number of steps was 4. Laboratory extraction carried out adopting the numerically optimized factors gave an extraction efficiency of 89.6%. The optimized parameters can be adopted when ex situ remediation of Pb-contaminated laterite soil is carried out using EDTA washing technique.

Accelerated Carbonation of Recycled Aggregates Using the Pressurized Supercritical Carbon Dioxide Sparging Process

The carbonation of recycled aggregate was accelerated by sparging with supercritical carbon dioxide (scCO2) to reduce the amount of time needed for carbonation, which is necessary for the pH neutralization of recycled aggregate. To accelerate the carbonation process, pressurized scCO2 was sparged into two different types of recycled aggregates immersed in water for 1 h, followed by standstill for 2 h (in total, a 3 h treatment process). The reduction of the pH of the treated aggregates due to carbonation was investigated using batch extraction experiments. A continuous column extraction experiment for the scCO2-sparged recycled aggregate was also performed to identify the effect of pH reduction under the condition of non-equilibrium reaction. From XRD, SEM/EDS, and TG/DTA analyses, much of the portlandite in the recycled aggregates was consumed. In its place, calcite was created as a secondary mineral during only 3 h of treatment (1 h scCO2 sparging and 2 h stationing), indicating satisfactory carbonation of the aggregate. The results of the batch extraction experiments for both of the two recycled aggregate types also showed that the average pH of scCO2-sparged aggregate decreased from 12.0 to &lt;9.8 (the tolerance limit for recycling). The pH of the eluent from the column packed with the scCO2-sparged aggregate also remained as &lt;9.8, suggesting that a 1 h scCO2 sparging process is sufficient to carbonate waste concrete aggregate and to create an alternative construction material resource.

From Coffee to Biodiesel—Deep Eutectic Solvents for Feedstock and Biodiesel Purification

Over three billion cups of coffee are consumed daily, making waste coffee grounds readily available throughout the world. Containing approximately 10–15 wt% of oil, they have great potential for biodiesel production. The goal of this work was to produce high quality biodiesel from waste coffee grounds. One fresh and four different types of waste coffee grounds were collected. Oil was extracted by the Soxhlet method with n-hexane and then purified via extractive deacidification with a potassium carbonate-based deep eutectic solvent. Biodiesels were synthesized by means of alkali catalyzed transesterification at different catalyst:methanol:oil mass ratios and reaction times. Impurities present in crude biodiesels were extracted with a choline chloride-based deep eutectic solvent. All batch extraction experiments were performed at room conditions in a small scale extractor. Optimal conditions for synthesis and purification were defined in order to assure high quality of the produced biodiesel. Additionally, continuous column extraction with the choline chloride-based solvent was tested as a purification method for crude biodiesel. Stabilization time and optimal biodiesel to solvent mass ratio were determined. The potassium carbonate-based solvent efficiently reduced the total acid number of the feedstock (deacidification efficiency ranged from 86.18 to 94.15%), while the one based on choline chloride removed free glycerol and glycerides from crude biodiesels. After continuous purification, the purified biodiesel was of excellent quality with glycerol and glyceride contents below the EN 14214 limit.

In situ reductive dissolution to remove Iodine-129 from aquifer sediments

The use of an aqueous reductant (Na-dithionite) with pH buffer (K-carbonate, pH 12) was evaluated in this laboratory study as a potential remedial approach for removing Fe oxide associated iodine and enhancing pump-and-treat extraction from iodine-contaminated sediments in the unconfined aquifer in the 200 West Area of the Hanford Site. X-ray fluorescence data of untreated sediment indicated that iodine was largely associated with Fe (i.e., potentially incorporated into Fe oxides), but XANES data was inconclusive as to valence state. During groundwater leaching, aqueous and adsorbed iodine was quickly released, then additional iodine was slowly released potentially from slow dissolution of one or more surface phases. The Na-dithionite treatment removed greater iodine mass (2.9x) at a faster rate (1–4 orders of magnitude) compared to leaching with groundwater alone. Iron extractions for untreated and treated sediments showed a decrease in Fe(III)-oxides, which likely released iodine to aqueous solution. Solid phase inorganic carbon and aqueous Ca and Mg analysis further confirmed that significant calcite dissolution did not occur in these experiments meaning these phases did not release significant iodine. Although it was expected that, after treatment, 127I concentrations would eventually be lower than untreated sediments, continued, elevated iodine concentrations for treated samples over 750 h were observed for leaching experiments. Stop flow events during 1-D column leaching suggested that some iodide precipitated within the first few pore volumes. Further, batch extraction experiments compared iodine-129/127 removal and showed that iodine-129 was more readily removed than iodine-127 suggesting that the two are present in different phases due to their different origins. Although significantly greater iodine is removed with treatment, the long-term leaching needs to be investigated further as it may limit dithionite treatment at the field scale.

Separation of Ac-225 from Lanthanide Fission Products using a Reverse Phase Chromatographic Process Incorporating a Solvent Impregnated Resin

Targeted α-particle therapy (TAT) has been shown in recent years to be a promising route for the treatment of various forms of cancer, and may serve as an alternative to more traditional cancer treatment options. TAT takes advantage of an α-emitting radionuclide’s ability to deliver cytotoxic doses of radiation to tumor cells while causing minimal damage to surrounding healthy tissue. This is possible because of the short path length and high linear energy transfer associated with α -particles, which are on the order of 100 μm or less and around 100 keV/μm, respectively. To this end, a number of α-emitting radionuclides have explored for therapeutic applications including Ac-225, Bi-213, Bi-212, At-211, and Ra-223 with others currently in development. Of these, Ac-225 in particular has proven itself to be an especially appealing isotope for the treatment of some cancers. The value of Ac-225 is derived in part from its four alpha decay chain, which includes Bi-213 (t1/2 = ∼46 minutes), which is in itself a desirable isotope for TAT. The targeted delivery of Ac-225 to tumor sites has been shown in a number of instances to be highly effective for the treatment of several forms of cancer when a conjugate with an antibody, peptide, or protein is produced which can carry the isotope to the target site. One of the more notable instances of the successful treatment of human cancer with Ac-225 has been in the treatment of prostate cancer, for which Ac-225 may be conjugated with Prostate Specific Membrane Antigen for targeted doses to prostate cancer tumor cells. Because of the proven efficacy of Ac-225-containing conjugate species in anticancer treatment applications, demand for this isotope is expected to rise above current production capabilities. The work presented herein describes a new method for the separation of Ac-225 from radiolanthanide impurities resulting from fission of proton irradiated Th-232 target foils. The process incorporates a solvent impregnated resin to achieve the separation, and is the first in a series of resins to be tested as alternatives to current technologies incorporating branched DGA resin. The current resin is comprised of an Amberlite XAD7HP resin that has been loaded with the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethane)sulfonamide ([Bmim][NTf2]) and the extractant N,N-dioctyldiglycolamic acid (DODGAA). Going forward, the resin will be tuned to achieve optimum results by loading the Amberlite scaffold with varying combinations of ionic liquids and extractants. Data presented will include batch extraction experiments including the solvent impregnated resin with complex matrices of metals (La-Lu, Sc, Y, U, Th, Ac) in HCl, HNO3, and citrate-phosphate buffer media over a range of pH. Additionally, results of dynamic column experiments will be presented, and comparisons will be made to separations technologies currently in use.

Development and environmental implication of pedotransfer functions of Cd desorption rate coefficients in historically polluted soils

The desorption rate is an important factor determining cadmium (Cd) ecotoxicity and pollution remediation in soils. The pedotransfer functions (PTFs) of desorption rate coefficients of fresh Cd in soils have been developed in literature. We hypothesized that the aging of Cd pollution would alter Cd desorption process. Taking historically polluted soils as the object, this study aimed at testing the hypothesis and developing new PTFs of desorption rate coefficients for historical Cd. 15 d batch extraction experiments and 13 kinetic models were employed to define Cd desorption rate coefficients in 27 historically polluted soil samples. Compared with fresh Cd, the desorption rate coefficients of historical Cd were lower, and the break time of biphasic desorption processes was retarded to 3 d (4320 min). Different with the usual models for fresh Cd desorption (e.g. parabolic diffusion and two constant rate models), the best models to mimic the historical Cd desorption processes were the pseudo first order, logarithmic, Elovich, and simple Elovich models. The rate-limiting step controlling Cd desorption was changed from the intraparticle diffusion to the interface reaction with aging of pollution. New PTFs of desorption rate coefficients of historical Cd were established (R2 ≥ 0.71). Cd desorption rate coefficients increased with organic matter and clay contents, but decreased with oxalate extractable Fe content, solution pH, cation exchange capacity, and silt content. The key soil properties influencing desorption rate coefficients were not altered by the aging of pollution. The developed PTFs could guide us to adjusting the ecotoxicity and pollution remediation of Cd in historically polluted field soils.

Effects of humic acid and fulvic acid on the sequestration of copper and carbon during the iron oxide transformation

In natural environments, the iron oxide transformation is associated with natural organic matter (NOM) and heavy metals. However, there is still a lack of knowledge on the dynamic interactions among NOM, iron oxides, and heavy metals during the iron oxide transformation process, which has significant implications on the fate of metals and carbon (C) in the environment. In this study, two types of NOM, fulvic acid and humic acid (FA and HA) were used to elucidate the influence of NOM on the iron oxide transformation and the dynamic distribution and speciation of Cu and C during the iron oxide transformation. The X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopy showed that both FA and HA decreased the rates of ferrihydrite transformation to hematite. The EXAFS analysis of Cu speciation and spherical aberration corrected scanning transmission electron microscope (Cs-STEM) showed that Cu could be incorporated into the hematite particles while HA and FA hindered the incorporation of Cu, consistent with the chemical extraction results. Compared with FA, HA resulted in more extractable Cu by diluted acid and less Cu incorporation into iron oxides. The Cs-STEM results showed that both HA and FA resulted in the formation of ellipsoidal hematite particles with a loose structure. Batch extraction experiments and the Cs-STEM imaging, collectively, indicated that HA might penetrate into the loose and porous structure of hematite nanoparticles, which was less evident for FA. Results in this study help to understand the environmental behaviors of C and Cu during the iron oxide transformation process and also shed light on the nanoscale mechanisms of C sequestration within iron oxides.

Effects of Diluents on the Separation of Minor Actinides from Lanthanides with Tetradodecyl-1,10-phenanthroline-2,9-diamide from Nitric Acid Medium.

To investigate the effective separation of actinides (Ans) from lanthanides (Lns), single-stage batch extraction experiments were performed with a novel extractant, tetradodecyl-1,10-phenanthroline-2,9-diamide (TDdPTDA) with various diluents such as 3-nitrobenzotrifluoride (F-3), nitrobenzene, and n-dodecane for Am, Cm, and Lns. The extraction kinetics with TDdPTDA was rapid enough to perform continuous extraction experiments using mixer-settler extractors. The slopes of the distribution ratio versus the TDdPTDA concentration and the distribution ratio versus the nitric acid concentration were similar for F-3 and nitrobenzene systems, but different from the n-dodecane system. These differences were attributed to the characteristics of the diluents. This study revealed high distribution ratios of Am (DAm) and Cm (DCm) for TDdPTDA, with the high separation factors (SFs) of Am from Lns enough for their separation.

Separation of Ac-225 from Lanthanide Fission Products using a Reverse Phase Chromatographic Process Incorporating a Solvent Impregnated Resin

Targeted α-particle therapy (TAT) has been shown in recent years to be a promising route for the treatment of various forms of cancer, and may serve as an alternative to more traditional cancer treatment options. TAT takes advantage of an α-emitting radionuclide’s ability to deliver cytotoxic doses of radiation to tumor cells while causing minimal damage to surrounding healthy tissue. This is possible because of the short path length and high linear energy transfer associated with α -particles, which are on the order of 100 μm or less and around 100 keV/μm, respectively. To this end, a number of α-emitting radionuclides have explored for therapeutic applications including Ac-225, Bi-213, Bi-212, At-211, and Ra-223 with others currently in development. Of these, Ac-225 in particular has proven itself to be an especially appealing isotope for the treatment of some cancers. The value of Ac-225 is derived in part from its four alpha decay chain, which includes Bi-213 (t1/2 = ∼46 minutes), which is in itself a desirable isotope for TAT. The targeted delivery of Ac-225 to tumor sites has been shown in a number of instances to be highly effective for the treatment of several forms of cancer when a conjugate with an antibody, peptide, or protein is produced which can carry the isotope to the target site. One of the more notable instances of the successful treatment of human cancer with Ac-225 has been in the treatment of prostate cancer, for which Ac-225 may be conjugated with Prostate Specific Membrane Antigen for targeted doses to prostate cancer tumor cells. Because of the proven efficacy of Ac-225-containing conjugate species in anticancer treatment applications, demand for this isotope is expected to rise above current production capabilities. The work presented herein describes a new method for the separation of Ac-225 from radiolanthanide impurities resulting from fission of proton irradiated Th-232 target foils. The process incorporates a solvent impregnated resin to achieve the separation, and is the first in a series of resins to be tested as alternatives to current technologies incorporating branched DGA resin. The current resin is comprised of an Amberlite XAD7HP resin that has been loaded with the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethane)sulfonamide ([Bmim][NTf2]) and the extractant N,N-dioctyldiglycolamic acid (DODGAA). Going forward, the resin will be tuned to achieve optimum results by loading the Amberlite scaffold with varying combinations of ionic liquids and extractants. Data presented will include batch extraction experiments including the solvent impregnated resin with complex matrices of metals (La-Lu, Sc, Y, U, Th, Ac) in HCl, HNO3, and citrate-phosphate buffer media over a range of pH. Additionally, results of dynamic column experiments will be presented, and comparisons will be made to separations technologies currently in use.

Extraction of Uranium(VI) and Plutonium(IV) with Tetra-Alkylcarbamides

ABSTRACTThe use of tetra-alkylcarbamides as novel extractants for the separation of uranium(VI) and plutonium(IV) by solvent extraction from spent nuclear fuels is investigated in this study. Batch extraction experiments show that tetra-alkylcarbamides strongly extract U(VI) with high distribution ratios. Plutonium(IV) can be co-extracted with U(VI) at high nitric acid concentration, while high U(VI)/Pu(IV) selectivities can be reached at lower acidity. Loading capacity experiments with high uranium concentrations show that alkyl chains longer than butyl are necessary to avoid third phase formation. Nevertheless, the viscosity of uranium-loaded solvents gets too high with alkyl chains longer than pentyl. Overall, this study shows that with TPU extractant (with four pentyl chains), an efficient co-extraction of uranium and plutonium can be reached (DU,Pu > 1) for a concentration of nitric acid higher than 4 mol•L−1, while the partition between uranium(VI) and plutonium(IV) could be operated even at 2 mol•L−1 nitric acid without redox chemistry.

Solvent extraction and stripping of copper in a Y-Y type microchannel reactor

The solvent extraction and stripping of copper have been conducted in a Y-Y type microchannel reactor. The experimental results demonstrate that the Y-Y type microchannel reactor can be used for both Cu extraction and Cu stripping. The effects of residence time, aqueous phase pH, and concentration of extractant on the extent of extraction were investigated. The results indicated that the extent of extraction and the separation factor using a Y-Y type microchannel reactor are greater than those obtained with a conventional batch extraction. The maximum extraction of copper reached 86.02%. Also, the stripping reaction was studied with respect to Cu2+ concentration in the loaded organic phase, H2SO4 concentration, and the organic/aqueous phase ratio. The maximum stripping of copper reached 98.94%.The overall volumetric mass transfer coefficients (KLα) were calculated to evaluate mass transfer characteristics. For comparison, conventional batch extraction experiments were also carried out, in parallel. The laminar flow pattern through the Y-Y microchannel was investigated by numerical simulation, and by experimental measurements. The maximum separation factors, βCu/Fe and βCu/Zn, were found to be 465.53 and 1249.70, respectively. Higher KLα values (0.4937–3.3969 s−1) were obtained for Cu within 5 s using a microchannel reactor compared with values (0.006–0.073 s−1) from batch experiments. Much higher overall volumetric mass transfer coefficients,KLα values (0.4937–3.3969 s−1) for Cu, and lower KLα values for Fe (0.0477–0.3173 s−1) and Zn (0.0395–0.2130 s−1), demonstrated an effective separation between Cu and Fe, Zn.

Experimental and simulation study of nylon 6 solid–liquid extraction process

Abstract The solid–liquid extraction process of nylon 6 to eliminate small molecules, i.e., caprolactam (CL), cyclic dimers (CD) and cyclic trimers (CT), is investigated in detail by both batch extraction experiments and numerical simulations. In the batch extraction experiments, due to the small molecules attaching to the polymeric surface, the basic physical mechanism shifts from surface diffusion to internal diffusion as the extraction proceeded. The experimental data are well reproduced by a diffusion model consisting of two distinct steps, characterized as surface diffusion and internal diffusion. Furthermore, based on the established mass transfer mechanism and diffusion model of the two distinct steps, the equilibrium constants and internal diffusion coefficients of CL, CD and CT are acquired. An industrial countercurrent extraction tower is further simulated. It is found that the extraction efficiency of CL can be significantly improved by increasing the temperature at the bottom portion of the tower. The elimination of CD, which can be greatly promoted by a high-concentration CL-water solution, is controlled by mass transfer resistance, whereas the removal of CL is mainly affected by the equilibrium.