Magnetically Assisted Chemical Separation Research Articles

High impact of uranyl ions on carrying-releasing oxygen capability of hemoglobin-based blood substitutes.

The effect of radioactive UO2 (2+) on the oxygen-transporting capability of hemoglobin-based oxygen carriers has been investigated in vitro. The hemoglobin (Hb) microspheres fabricated by the porous template covalent layer-by-layer (LbL) assembly were utilized as artificial oxygen carriers and blood substitutes. Magnetic nanoparticles of iron oxide (Fe3 O4 ) were loaded in porous CaCO3 particles for magnetically assisted chemical separation (MACS). Through the adsorption spectrum of magnetic Hb microspheres after adsorbing UO2 (2+) , it was found that UO2 (2+) was highly loaded in the magnetic Hb microspheres, and it shows that the presence of UO2 (2+) in vivo destroys the structure and oxygen-transporting capability of Hb microspheres. In view of the high adsorption capacity of UO2 (2+) , the as-assembled magnetic Hb microspheres can be considered as a novel, highly effective adsorbent for removing metal toxins from radiation-contaminated bodies, or from nuclear-power reactor effluent before discharge into the environment.

Adsorption of U(VI) from aqueous solution by Triocthylamine (TOA) functionalized magnetite nanoparticles as a novel adsorbent

Adsorption of U (VI) from aqueous solutions was investigated using magnetically assisted chemical separation (MACS) process. In the present study, Triocthylamine (TOA) functionalized magnetite nanoparticles (TOAFMNPs) were applied as a novel adsorbent for adsorption of U (VI) from aqueous solutions. The effects of initial pH, Triocthylamine to magnetite nanoparticles weight ratio, amount of adsorbent, stirring time and initial U(VI) concentration on U(VI) adsorption efficiency were investigated by batch experiments. The adsorption of U(VI) using this adsorbent was pH dependent, and the optimal pH was 5.5. In kinetics studies, the adsorption equilibrium can be reach within 20 min., and the experimental data were well fitted by the pseudo-second-order model. The highest value of U(VI) adsorption (93.8%) was achieved in optimum conditions. The Langmuir isotherm model correlates well with the U(VI) adsorption equilibrium data for the concentration range 10-80 mg/l. The maximum U(VI) adsorption capacity onto adsorbent was 27.5 mg/g at room temperature. Present study suggests that TOAFMNPs could be employed as a potential adsorbent for U(VI) adsorption, and also could provide a simple and fast separation method for removal of U(VI) ion from solutions

Separation of hafnium and zirconium using TBP modified ferromagnetic nanoparticles: Effects of acid and metals concentrations

In the magnetically assisted chemical separation (MACS) process, ferromagnetic nanoparticles modified by solvent extractant are used to separate hafnium from zirconium. The contaminant-loaded nanoparticles are recovered using a magnetic field. The contaminants attached to the magnetic nanoparticles are subsequently removed using a small volume of stripping agent. In this study, tributylphosphate (TBP) modified magnetic nanoparticles with particle size of 10nm were evaluated for the extraction and separation of hafnium from zirconium. Laboratory scale investigations were carried out on the effects of type and concentration of acid, and also concentration of Hf and Zr ions on the efficiency of extraction and separation stages. It was found that 4M hydrochloric acid, 10ppm Zr and 7.5ppm Hf ions gave the best results with SF=1.4 and 1.5 for the extraction and stripping stages, respectively.

N,N,N′,N′-tetraoctyl-3-oxapentane-1,5-diamide impregnated magnetic particles for the uptake of lanthanides and actinides from nuclear waste streams

A novel, simple technique based on magnetically assisted chemical separation (MACS) has been developed for the uptake of lanthanides and actinides from pure nitric acid solutions as well as from Simulated Pressurized Heavy Water Reactor-High Level Waste (PHWR-SHLW). Uptake profiles of various metal ions, such as Pu(IV), U(VI), Th(IV), Am(III), Eu(III), Sr(II), Cs(I) and Fe(III) were investigated as a function of time and nitric acid concentrations usingN,N,N′,N′-tetraoctyl-3-oxapentane-1,5-diamide (TODGA) impregnated magnetic particles and compared withN,N′-dimethyl-N,N′-dibutyl tetradecyl malonamide (DMDBTDMA) and trialkyl phosphine oxide coated magnetic particles and also with TODGA coated extraction chromatographic resins. The uptake of various metal ions follows the order Eu(III) > Am(III) > Th(IV) > Pu(IV) > U(VI) > Sr(II) > Fe(III) > Cs(I) in pure nitric acid solutions. On the other hand, distinctly high distribution coefficient (Kd) value has been observed for Pu(IV) as compared to Eu(III) and Am(III) in SHLW. Further, no significant extraction of Cs(I) or Sr(II) was observed in SHLW. Also, at any acidity theKdvalue of a given metal ion is less in the SHLW as compared to that in pure HNO3, apparently due to the co-extraction of the other metal ions present in SHLW. The loading capacity of the TODGA impregnated magnetic particles with respect to Th(IV), U(VI) and Eu(III) was determined, along with the distribution isotherms to simulate multiple contacts. The adsorption models of Langmuir and Freundlich were fitted to the experimental data and best correlations was obtained for Langmuir model suggesting monolayer adsorption is the prevalent mechanism. The stability and reusability of the TODGA coated magnetic particles was also assessed.

Evaluation of Cyanex 923-coated magnetic particles for the extraction and separation of lanthanides and actinides from nuclear waste streams

In the magnetically assisted chemical separation (MACS) process, tiny ferromagnetic particles coated with solvent extractant are used to selectively separate radionuclides and hazardous metals from aqueous waste streams. The contaminant-loaded particles are then recovered from the waste solutions using a magnetic field. The contaminants attached to the magnetic particles are subsequently removed using a small volume of stripping agent. In the present study, Cyanex 923 (trialkylphosphine oxide) coated magnetic particles (cross-linked polyacrylamide and acrylic acid entrapping charcoal and iron oxide, 1:1:1, particle size=1–60 μm) are being evaluated for the possible application in the extraction and separation of lanthanides and actinides from nuclear waste streams. The uptake behaviour of Th(IV), U(VI), Am(III) and Eu(III) from nitric acid solutions was investigated by batch studies. The effects of sorption kinetics, extractant and nitric acid concentrations on the uptake behaviour of metal ions were systematically studied. The influence of fission products (Cs(I), Sr(II)) and interfering ions including Fe(III), Cr(VI), Mg(II), Mn(II), and Al(III) were investigated. The recycling capacity of the extractant-coated magnetic particles was also evaluated.

Novel separation and preconcentration of trace amounts of copper(II) in water samples based on neocuproine modified magnetic microparticles

A novel, simple method based on magnetically assisted chemical separation (MACS) has been developed for analytical purposes. In this method, neocuproine modified magnetic microparticles was used for selective extraction and preconcentration of copper(II) ions from aqueous solutions. The advantages of this method include consumption of organic solvents almost eliminated and applications on unclear (containing suspended particles) samples without any preliminary filtration step. This method combines simplicity and selectivity of solvent extraction with easy separation of magnetic microparticles from solution with magnet. In addition, it can be considered as a simple method for determination of partition coefficient. The influence of different parameters, such as presence of extractant, amount of extractant loaded on the microparticles, reducing agent, pH, equilibrium time, ionic strength, type and least amount of stripping solution and limit of detection, were evaluated. Also, the effects of various cationic and anionic interferences on the percent recovery of copper were studied. Copper ions were extracted from solution at pH 6 and were stripped from microparticles with 0.5 M HNO 3. Extraction efficiencies for solutions with volumes up to 100 ml were >99%. Limit of detection was 1.5 μg/l. The method was applied to the recovery and determination of copper in different water samples.

Chemical Synthesis, Processing, and Characterization of Nanostructured Fe−B for the Magnetically Assisted Chemical Separation of Hazardous Waste

Nanostructured Fe−B alloys have been synthesized by reducing aqueous FeCl2 with potassium borohydride both in the presence and in the absence of an applied magnetic field and investigated for the separation of hazardous waste in the magnetically assisted chemical separation (MACS) process. Linear chain and discrete particle microstructures of Fe−B are obtained depending on the reaction conditions. The Fe−B samples exhibit a saturation magnetization as high as 190 emu/g after annealing in a 90%Ar−10%H2 atmosphere at 400 °C. The Fe−B magnetic materials are then encapsulated within a uniform polyacrylamide matrix using a solution-based technique developed in this study. With an optimum surfactant concentration, homogeneous Fe−B/polyacrylamide composite materials could be readily prepared. The particle size of the composite could be controlled by varying the monomer concentration during the polymerization. Laboratory level testing with a surrogate species (cobalt ions) indicates that these materials are highl...

Separation of Uranium from Nitric- and Hydrochloric-Acid Solutions with Extractant-Coated Magnetic Microparticles

The magnetically assisted chemical separation (MACS) process utilizes selective magnetic microparticle composites to separate dissolved metals from solution. In this study, MACS particles were coated with neutral and acidic organophosphorus extractants,octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO), tributyl phosphate (TBP), trioctylphosphine oxide (TOPO), and bis(2-ethyl-hexyl)phosphoric acid (D2EHPA or HDEHP) and were evaluated for the separation of uranyl ions from nitric- and hydrochloric-acid solutions. The results suggest that a synergistic interaction between the particle surface and solvent coating may explain why the particles display, in some cases, orders of magnitude of higher partitioning coefficients than are estimated from solvent-extraction measurements. Particles coated with TBP and those coated with a combination of TOPO and D2EHPA displayed the most desirable characteristics for removing uranium from dilute acid environments typical of contaminated groundwater. Uranium separation from moderate to highly acidic waste streams typical of Department of Energy (DOE) nuclear wastes is best accomplished using particles coated with a combination of CMPO and TBP. The submitted manuscript has been created by the University of Chicago as Operator of Argonne National Laboratory (“Argonne”) under Contract No. W-31-109-ENG-38 with the U.S. Department of Energy. The U.S. Government retains for itself, and others acting on its behalf, a paid-up, nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.

Extractant-coated magnetic particles for cobalt and nickel recovery from acidic solution

Waste minimization and recycling practices can often constitute a significant fraction of industrial operating costs. Magnetically assisted chemical separation (MACS) is a simple, cost-effective process that utilizes micrometer-sized magnetic composite materials containing a sorbed layer of chelating or ion exchange material. This paper presents the use of MACS particles for recovering cobalt and nickel from acidic solution.

EVALUATION OF EXTRACTANT-COATED FERROMAGNETIC MICROPARTICLES FOR THE RECOVERY OF HAZARDOUS METALS FROM WASTE SOLUTION

A magnetically assisted chemical separation (MACS) process developed at Argonne National Laboratory is a compact method for the extraction of transuranic (TRU) metals from, and volume reduction of, liquid waste streams that exist at many DOE sites. The MACS process utilized the selectivity afforded by solvent extractant/ion-exchange materials in conjunction with magnetic separation to provide a more efficient chemical separation. Recently, the principle of the MACS process has been extended to the evaluation of acidic organophosphorus extractants for hazardous metal recovery from waste solutions. Moreover, process scale-up design issues were addressed in respect to particle filtration and recovery. Two acidic organophosphorus compounds have been investigated for hazardous metal recovery, bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex{reg_sign} 272) and bis(2,4,4-trimethylpentyl) dithiophosphinic acid (Cyanex{reg_sign} 301). These extractants coated onto magnetic microparticles demonstrated superior recovery of hazardous metals from solution as compared with data from solvent extraction experiments. The results illustrate the possibility for diverse applications of this technology for dilute waste streams. Preliminary process scale-up experiments with a high-gradient magnetic separator at Oak Ridge National Laboratory revealed the potential for very low microparticle loss rates.

EVALUATION OF EXTRACTANT-COATED FERROMAGNETIC MICROPARTICLES FOR THE RECOVERY OF HAZARDOUS METALS FROM WASTE SOLUTION

ABSTRACT A magnetically assisted chemical separation (MACS) process developed at Argonne National Laboratory is a compact method for the extraction of transuranic (TRU) metals from, and volume reduction of, liquid waste streams that exist at many DOE sites. The MACS process utilized the selectivity afforded by solvent extractant/ion-exchange materials in conjunction with magnetic separation to provide a more efficient chemical separation. Recently, the principle of the MACS process has been extended to the evaluation of acidic organophosphorus extractants for hazardous metal recovery from waste solutions. Moreover, process scale-up design issues were addressed in respect to particle filtration and recovery. Two acidic organophosphorus compounds have been investigated for hazardous metal recovery, bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex® 272) and bis(2,4,4-trimethylpentyl) dithiophosphinic acid (Cyanex® 301). These extractants coated onto magnetic microparticles demonstrated superior recovery of hazardous metals from solution as compared with data from solvent extraction experiments. The results illustrate the possibility for diverse applications of this technology for dilute waste streams. Preliminary process scale-up experiments with a high-gradient magnetic separator at Oak Ridge National Laboratory revealed the potential for very low microparticle loss rates.

Optimizing the coating process of organic actinide extractants on magnetically assisted chemical separation particles

Abstract The coatings of ferromagnetic-charcoal-polymer microparticles (1–25 gm) with organic extractants specific for actinides were optimized for use in the magnetically assisted chemical separation (MACS) process. The organic extractants, octyl (phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) dissolved in tributyl phosphate (TBP), coated the particles when a carrier organic solvent was evaporated. Coated particles were heated in an oven overnight to drive off any remaining carrier solvent and fix the extractants on the particles. Partitioning coefficients for americium obtained with the coated particles routinely reached 3000–4000 ml g−1, approximately 10 times the separation efficiency observed with the conventional solvent extraction system using CMPO and TBP.

Sorption Capacity of Ferromagnetic Microparticles Coated with CMPO

Magnetically assisted chemical separation (MACS) was developed at Argonne National Laboratory as a compact process for reducing the volume of high-level aqueous waste streams that exist at many U.S. Department of Energy sites. In the MACS process, ferromagnetic particles coated with solvent extractants are used to selectively separate transuranic nuclides and heavy metals from aqueous wastes. The contaminant-loaded particles are recovered from the waste stream by using a magnet. For the recovery of transuranic species the extractant used is octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) dissolved in tri-n-butyl phosphate (TBP). To better understand the extraction chemistry of this solvent/particle system, europium was used to monitor the sorption capacity of the MACS particles for lanthanides and actinides. Europium concentrations varying from 10−7 M to 10−1 M were prepared with 3M NaNO3 in 0.1M HNO3. Neutron activation analysis was used to measure the concentration of europium. The sorption capacity was evaluated, along with the sorption isotherms to simulate multiple contact stages. The maximum absorption capacities obtained was 0.62 mmol/g. The adsorption models of Langmuir and Freundlich and the extended Langmuir model of Brunauer, Emmett, and Teller (BET) were fitted to the data. The best correlations were obtained from the Langmuir and BET models, a result that supports a monolayer adsorption mechanism. The Langmuir and BET models suggested a loading capacity of 0.33 mmol/g and 0.25 mmol/g, respectively. The Freundlich model results support favorable metal loading with a 1/n value of 0.3. The submitted manuscript has been authored by a contractor of the U.S. Government under contract No. W-31-109-ENG-38. Accordingly, the U.S. Government retains a non-exclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purposes.