A kind of Cloud-Point Extraction Technique of utilizing is from the method for aqueous phase enriched uranium, thorium
Technical field
The invention belongs to the nuclear fuel cycle field, be specifically related to a kind of cloud point extraction that utilizes from the method for aqueous phase enriched uranium, thorium.
Background technology
Uranium is a kind of topmost nuclear fuel in the present Nuclear energy uses, and thorium is the potential resources of Nuclear energy uses.Simultaneously, both all have biological pathogenic.Based on application prospect and the toxicity of uranium, thorium, uranium, thorium in effectively enrichment, separation, testing environment and the biological sample are very important.
Cloud point extraction (cloud point extraction, be called for short CPE) technology is a kind of novel separation and concentration technology that developed recently gets up, the solubilising that mainly utilizes nonionic surfactant solution and phase-splitting realize to the enrichment of solute with separate.To nonionic surfactant solution, when temperature was higher than certain value, solution becomes was muddy, is separated; One is the very little rich tensio-active agent phase of volume mutually, and another is that surfactant concentration is the water of micelle-forming concentration mutually.This phenomenon is the cloud point phenomenon, and corresponding temperature is called cloud point.Utilize this character, in cloud point extraction, metal ion and extraction agent form in the nonpolar nuclear that hydrophobic title complex enters micella; When temperature is higher than the cloud point of nonionogenic tenside, be separated, the metal ion that is solubilized in the micella is separated out with tensio-active agent, thereby realizes the extracting and separating of metal ion.Compare with conventional solvent extraction, this technology need not be used a large amount of poisonous and hazardous organic solvents, having the remarkable advantages such as coefficient of concentration is high, simple to operate, low-cost, the safety of being separated, high speed, is a kind of novel eco-friendly isolation technique, has good industrial application potentiality.
Adopt more existing reports of enrichment U (VI), Th (IV) of Cloud-Point Extraction Technique, such as (Draye M. such as Draye, et al, J.Chem.Technol.Biotechnol., 2006,81,1872) adopting oxine (8-HQ) is extraction agent, the extraction UO take TX-114 as tensio-active agent
2 2+When pH>4, extraction efficiency can reach 100%, but is reduced to gradually pH<2 with pH, and extraction efficiency levels off to 0.Dibenzoyl (DBM), 1-(pyridylazo)-acidic extractants such as beta naphthal (PAN) also are used to cloud point extraction UO
2 2+, Th
4+In, but all have substantially unfruitful problem under the acidic conditions.And in practical application, in nuclear fuel reprocessing, the acidity of solution often is in a higher level, thereby has limited the application of cloud point extraction.Neutral-neutral Extractants such as tributyl phosphate (TBP), has preferably effect of extracting under acidic conditions in the conventional solvent extraction, but relatively poor (Pashalidis I., et al., J.Radioanal.Nucl.Chem. of effect in cloud point extraction, 2010,286,461).
Summary of the invention
The purpose of this invention is to provide a kind of method of utilizing Cloud-Point Extraction Technique to extract U (VI) or Th (IV) from aqueous phase.
Method from aqueous phase extraction U (VI) or Th (IV) provided by the present invention is to adopt the cloud point extraction method, take trialkylphosphine oxide (TRPO) as extraction agent, Diethylene Glycol list [(1,1,3, the 3-tetramethyl butyl) phenyl] ether (TX-114) is tensio-active agent, C
nMimNTf
2Class (be 1-alkyl-3-Methylimidazole two trifluoromethane sulfimides) ionic liquid is additive, from the aqueous solution that contains uranyl ion or thorium ion of different condition with certain ionic strength with UO
2 2+Or Th
4+Extracting and separating out efficiently.
C involved in the present invention
nMimNTf
2The specific examples of class ionic liquid comprises: C
2MimNTf
2, C
4MimNTf
2, C
6MimNTf
2, C
8MimNTf
2, C
10MimNTf
2, C
12MimNTf
2Deng, these ionic liquids can use separately, also one or more can be mixed together.
Ionic liquid is the organic compound that a class fully is comprised of zwitterion and is in a liquid state under room temperature or close temperature, have nontoxic, without remarkable vapour pressure, environmentally friendly, without flammable, fusing point is low and liquid zone between the advantages such as wide, Heat stability is good, solubilized gas chromatography and inorganics, be described as " green solvent ".Ionic liquid can change the physicochemical property of surfactant soln as additive.The present invention uses C
nMimNTf
2The class ionic liquid is additive, has greatly improved the accumulation ability of extraction system to uranium, thorium ion.
TRPO of the present invention both can be single material, such as trioctylphosphine oxide (TOPO) (TOPO), triheptylphosphine oxide, trihexylphosphine oxide etc.; Also can be the mixture of two or more trialkylphosphine oxides; Certainly also can be the trialkylphosphine oxide compound that contains different alkyl chain lengths; Or be the mixture of above-mentioned various materials.The extraction ability of trialkyl (mixing) phosphine oxide is similar to TOPO.
It is tensio-active agent that the present invention adopts TX-114, and the concentration of TX-114 in the aqueous solution is generally 0.008-0.02mol/L, preferred 0.01-0.02mol/L; Adopt TRPO as extraction agent, the concentration of TRPO in the aqueous solution is generally 0-0.005mol/L (but not comprising 0mol/L), preferred 0.0002-0.002 mol/L; Adopt C
nMimNTf
2The class ionic liquid is as additive, C
nMimNTf
2Concentration in the aqueous solution is generally 0-0.004mol/L (but not comprising 0mol/L), preferred 0.0002-0.003mol/L.Generally speaking, extracted aqueous phase UO
2 2+Or Th
4+Concentration be 0-0.0001mol/L, preferred 0-0.00005mol/L.
When the ionic strength of extraction system does not reach 0.05mol/L, can be by in extraction system, adding salt (such as NaNO
3, NaCl) regulate.The ionic strength of described extraction system is preferred 〉=0.5mol/L.
Among the present invention, water condition to be extracted is variable, and this aqueous phase can also comprise the acid (HNO for example of different concns except the uranyl ion or thorium ion that contain different concns
3, HCl) and salt (NaNO for example
3, NaCl) etc. impurity.Utilize TRPO-C
nMimNTf
2Using cloud point extraction system can be from the efficient extracting and enriching U of the aqueous phase of above various different conditions (VI), Th (IV).
The present invention is with the two trifluoromethane sulfimide (C of 1-alkyl-3-Methylimidazole
nMimNTf
2) class ionic liquid, tensio-active agent TX-114 and Neutral-neutral Extractants trialkylphosphine oxide (TRPO) be combined, obtained that U (VI), Th (IV) are had the extraction system of efficient extraction ability, usually o'clock all significantly Extraction of Uranium, thorium ion in pH value≤6 have better application prospect.
Description of drawings
Fig. 1 be the adding of different ionic liquid on the histogram of the impact of cloud point extraction uranium, Extraction of thorium rate (1: without ionic liquid, 2:C
2MimNTf
2, 3:C
4MimNTf
2, 4:C
6MimNTf
2, 5:C
8MimNTf
2, 6:C
10MimNTf
2, 7:C
12MimNTf
2); Wherein, [TX-114]=0.01mol/L, [TOPO]=0.0005mol/L, [UO
2 2+]=0.00005mol/L or [Th
4+]=0.00005mol/L, [NaNO
3]=0.1mol/L, [ILs]=0.001mol/L.
Fig. 2 is TOPO-C
4MimNTf
2The cloud point system is to the schematic diagram that concerns of the percentage extraction of uranium and TX-114 concentration; Wherein, [TOPO]=0.0005mol/L, [UO
2 2+]=0.00005mol/L, [NaNO
3]=0.1mol/L, [C
4MimNTf
2]=0.001mol/L.
Fig. 3 is TOPO-C
4MimNTf
2The cloud point system is to the schematic diagram that concerns of the percentage extraction of uranium and TOPO concentration; Wherein, [TX-114]=0.01mol/L, [UO
2 2+]=0.00005mol/L, [NaNO
3]=0.1mol/L, [C
4MimNTf
2]=0.001mol/L.
Fig. 4 is TOPO-C
4MimNTf
2The cloud point system is to percentage extraction and the C of uranium
4MimNTf
2Concentration concern schematic diagram; Wherein, [TX-114]=0.01mol/L, [TOPO]=0.0005mol/L, [UO
2 2+]=0.00005mol/L, [NaNO
3]=0.1mol/L.
Fig. 5 is the schematic diagram that concerns of cloud point extraction uranium, Extraction of thorium rate and aqueous phase acidity; Wherein, [TX-114]=0.01mol/L, [TOPO]=0.0005mol/L, [UO
2 2+]=0.00005mol/L or [Th
4+]=0.00005mol/L, [NaNO
3]=0.1mol/L, [ILs]=0.001mol/L.
Fig. 6 is the schematic diagram that concerns of the percentage extraction of cloud point extraction uranium and water salinity; Wherein, [TX-114]=0.01mol/L, [TOPO]=0.0005mol/L, [UO
2 2+]=0.00005mol/L, [ILs]=0.001mol/L.
Embodiment
The present invention will be described below by specific embodiment, but the present invention is not limited thereto.
Experimental technique described in the following embodiment if no special instructions, is ordinary method; Described reagent and material if no special instructions, all can obtain from commercial channels.
Embodiment 1, utilize cloud point extraction to extract UO from aqueous phase
2 2+Or Th
4+
When carrying out extraction experiments, in the 10mL centrifuge tube, add successively quantitative tensio-active agent TX-114, extraction agent TOPO, ionic liquid, uranyl ion (UO
2 2+) or thorium ion (Th
4+) solution and NaNO
3Solution is settled to 10mL with three distilled water.Shake up rear 70 ℃ of constant temperature 2h, while hot centrifugation, the concentration (measuring method: ICP-AES is inductively coupled plasma atomic emission) of getting upper water facies analysis U (VI) or Th (IV).Extraction enters the U (VI) of tensio-active agent phase or the concentration of Th (IV) is tried to achieve with minusing, tries to achieve thus percentage extraction E.
TX-114 concentration is not that 0.01mol/L, TOPO concentration are 0.0005mol/L, NaNO in acid adding and the aqueous solution outside
3Concentration is under the condition of 0.1mol/L, does not add or add different C
nMimNTf
2Ionic liquid is to containing uranyl ion ([UO
2 2+]=0.00005mol/L) or thorium ion ([Th
4+Uranyl ion or thorium ion extract in the aqueous solution of]=0.00005mol/L), measure percentage extraction.The results are shown in Figure 1 (1: without ionic liquid, 2:C
2MimNTf
2, 3:C
4MimNTf
2, 4:C
6MimNTf
2, 5:C
8MimNTf
2, 6:C
10MimNTf
2, 7:C
12MimNTf
2).
As shown in Figure 1, outside, under the condition of acid adding, when TX-114 concentration is 0.01mol/L in the aqueous solution, do not adopt separately the UO of the TOPO cloud point extraction 0.00005mol/L of 0.0005mol/L
2 2+And Th
4+, extraction efficiency is~36% and 30%.In system, add 0.001mol/L C
2MimNTf
2The time, extraction efficiency all increases to~and 75% and~66%.With C
2MimNTf
2Replace with respectively C
4MimNTf
2, C
6MimNTf
2, C
8MimNTf
2, C
10MimNTf
2Or C
12MimNTf
2The time, the extraction efficiency of the extraction system of U and C
2MimNTf
2System is basic identical; For the extraction system of Th, add C
4MimNTf
2, C
6MimNTf
2, C
8MimNTf
2System extraction efficiency with add C
2MimNTf
2System is basic identical, and adds C
10MimNTf
2And C
12MimNTf
2The system extraction efficiency decrease.
With C
4MimNTf
2-CPE system extraction U (VI) is example, investigates the impact that various conditions change.Under the condition of acid adding, keeping TOPO concentration is not 0.0005mol/L, NaNO outside
3Concentration is 0.1mol/L, C
4MimNTf
2Concentration is 0.001mol/L, changes TX-114 concentration extraction U (VI) (concentration 0.00005mol/L), measures percentage extraction.As shown in Figure 2, increase with TX-114 concentration, system increases the extraction efficiency of uranyl ion, but lower phase volume increases.So, preferred 0.01-0.02mol/L.
Fig. 3 is under the condition of acid adding outside not, and keeping TX-114 concentration is 0.01mol/L, NaNO
3Concentration is 0.1mol/L, C
4MimNTf
2Concentration is 0.001mol/L, the variation of percentage extraction when changing TOPO extraction U (VI) (concentration 0.00005mol/L).Increase with TOPO concentration, system increases the extraction efficiency of uranyl ion.When TOPO concentration reached 0.002mol/L, extraction efficiency reached 100%.
Under the condition of acid adding, TX-114 concentration is not that 0.01mol/L, TOPO concentration are that 0.0005mol/L extracts U (VI) (concentration 0.00005mol/L) in the aqueous solution outside, measures percentage extraction.With uranyl ion percentage extraction (E) and C
4MimNTf
2The concentration mapping the results are shown in Figure 4.As shown in Figure 4, outside not under the condition of acid adding, when TX-114 concentration in the aqueous solution is that 0.01mol/L, TOPO concentration are when being 0.0005mol/L extraction 0.00005mol/L U (VI), with C in the water
4MimNTf
2Concentration increases, and system increases the extraction efficiency of uranyl ion, works as C
4MimNTf
2When concentration reached 0.003mol/L, extraction efficiency was near 90%.
Adopting TX-114 concentration is that 0.01mol/L, TOPO concentration are 0.0005mol/L, C
4MimNTf
2When concentration was system extraction 0.00005mol/L U (VI), the Th (IV) of 0.001mol/L, extraction efficiency changed with the variation of concentrations of aqueous nitric acid, as shown in Figure 5.With extraction UO
2 2+Be example, when existing without other acid, the pH of solution is about 6.Separately TOPO exists down, increases with acidity, the percentage extraction of U (VI) is improved, when acidity greater than 1moldm
-3The time, the percentage extraction of uranyl ion reduces.Work as C
4MimNTf
2Add (TOPT-IL-U curve among the figure) after the extraction system, with not contain ion liquid system identical, but percentage extraction all remains on more than 60% with the variation tendency of acidity variation extraction rate.In general, the TOPO using cloud point extraction system of ionic liquid participation can extract U (VI), Th (IV) in a larger Acidity Range.
When adopting the inventive method, need in the extraction system to guarantee that certain ionic strength is separated with realization.Adopting TX-114 concentration is that 0.01mol/L, TOPO concentration are 0.0005mol/L, C
4MimNTf
2When concentration was the system extraction 0.00005mol/L U (VI) of 0.001mol/L, extraction efficiency changed with the variation of water sodium nitrate concentration, as shown in Figure 6.With the increase of water salinity, the uranyl ion extraction efficiency increases, and works as NaNO
3Concentration is 0.05mol/L (ionic strength is about 0.05mol/L), and U (VI) percentage extraction is 60%, works as NaNO
3Concentration is during greater than 0.5mol/L (ionic strength is greater than 0.5mol/L), and percentage extraction is substantially constant.