Rubidium and cesium adsorbent as well as preparation method and application thereof

Abstract

The invention provides a rubidium and cesium adsorbent and a preparation method and application thereof. The preparation method comprises the following steps: providing a doped and modified Prussian blue analogue, wherein the Prussian blue analogue comprises a Prussian blue matrix material and a transition metal doping element doped in the Prussian blue matrix material; granulating a mixed material containing the doped and modified prussian blue analogue and a granulating agent to obtain a rubidium and cesium adsorbent precursor; a mixed reaction system containing the rubidium and cesium adsorbent precursor and a surface modifier are subjected to a reaction, the surface modifier contains one or more functional structures of an amino group, a sulfonic group, a carboxyl group, a sulfydryl group, an acryloyloxy group, an epoxy group, a crown ether structure and a calixarene structure, and therefore the rubidium and cesium adsorbent is obtained. Through a multi-aspect synergistic strategy of transition metal doping, granulation and surface modification, the prepared rubidium and cesium adsorbent has good stability and high adsorption capacity, and has strong selectivity to Cs < + > / Rb < + >.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rubidium and cesium adsorption materials, and particularly relates to a rubidium and cesium adsorbent and a preparation method and application thereof. BACKGROUND

[0002] As alkali metal elements, rubidium (Rb) and cesium (Cs) exhibit high chemical activity due to the easy loss of the outermost single electron. Their unique photoelectric properties, low ionization energy and strong ion exchange capacity make them have wide applications in new energy, new materials, night vision equipment, optical fiber communication and catalysis.

[0003] In nature, Rb and Cs resources are distributed in hard rock mines such as lithium mica and cesium spar, as well as liquid resources such as seawater, geothermal water, salt lake brine and solid waste resource leaching solution. With the gradual depletion of hard rock mines and the environmental pollution problems caused by traditional extraction methods (such as high-temperature calcination and strong acid and alkali leaching), the leaching solution resources in the comprehensive utilization process of salt lake brine and solid waste resources containing rubidium and cesium become important alternative resources due to their abundant reserves. However, the concentration of Rb⁺ and Cs⁺ in brine and leaching solution is low, and they coexist with high-concentration K⁺, Na⁺ and other ions (in some cases, the concentration of K⁺, Na⁺ is thousands to hundreds of thousands times higher than that of Rb⁺ / Cs⁺). In addition, as the concentration increases, a large amount of rubidium and cesium ions will be carried away with the precipitation of potassium, making the separation and extraction of Rb⁺ / Cs⁺ extremely challenging. + + + + + + + +

[0004] The existing solvent extraction method and precipitation method have problems such as organic pollution, high cost and low adaptability, while the adsorption method has become a research hotspot due to its high efficiency, low consumption and environmental protection characteristics. The adsorption method usually uses inorganic adsorbents such as aluminosilicates (such as zeolites, montmorillonite, etc.), heteropolyacid salts, polyvalent metal acid salts, hydrated oxides and metal ferrocyanides, iron cyanides, etc. Among them, Prussian blue analogues (PBAs, general formula: M1[M2(CN)6], wherein M1 and M2 are transition metals) have unique pore structures and certain selectivity, and are considered as one of the adsorbents with good application potential. However, the existing PBAs face four core problems: 1) poor structural stability: the skeleton is easy to collapse (such as Fe-CN-Co bond rupture) in acidic (for example, pH<3) or alkaline (for example, pH>10) environment, leading to the dissolution of metal ions; 2) insufficient selectivity: in the presence of high-concentration K⁺, Cs + / Rb + ​​​​​​​​3) Low mechanical strength: PBAs are mostly ultra-fine powders, which cannot be directly used in industrial fixed bed, adsorption tower, etc., and need to be granulated, but the existing granulation process will cause more than 30% adsorption capacity loss; 4) Short cycle life: in the elution process (such as using 1 M HNO3 for elution), it is easy to cause the loss of active sites, and the capacity will attenuate after recycling. SUMMARY

[0005] To solve all or part of the above technical problems, the present application provides the following technical solutions: The first aspect of the present application provides a preparation method of rubidium and cesium adsorbent, comprising: Granulating the mixture containing Prussian blue type material and granulating agent to obtain a rubidium and cesium adsorbent precursor; Reacting the mixed reaction system containing the rubidium and cesium adsorbent precursor and a surface modifier, the surface modifier containing a functional structure of one or more of amino, sulfonic acid group, carboxyl, mercapto, acryloyloxy, epoxy, crown ether structure, and calixarene structure, to obtain a rubidium and cesium adsorbent.

[0006] The present application uses a surface modifier containing a specific functional group and / or a specific structure to graft and modify the surface of the granulated adsorbent, strengthens its specific recognition of Cs + / Rb + , and solves the problem of selective decrease of existing Prussian blue analogs in the presence of high concentration of potassium ions. + / Rb +

[0007] In some embodiments, the Prussian blue type material is a doped and modified Prussian blue analog, which includes a Prussian blue type base material and a transition metal doping element doped therein.

[0008] By optimizing the crystal structure of the Prussian blue type material through transition metal doping, the acid and alkali resistance is enhanced, and the metal dissolution rate is reduced, so that the adsorbent has high adsorption capacity and long service life, and solves the problem of easy collapse of the skeleton of existing Prussian blue analogs in strong acid and strong alkali environment. That is, the preferred scheme obtains an adsorbent with good stability, high adsorption capacity and strong selectivity for Cs + / Rb + by means of the multi-aspect synergistic strategy of "transition metal doping-granulation-surface modification".

[0009] ​Further, the chemical formula of the Prussian blue type base material is K2A[Fe(CN)6], wherein A includes one or more combinations of Mg, Fe, Co, Ni, and Cu, the transition metal doping element includes one or more combinations of Al, Co, Mn, Zr, Zn, Cu, and Ni, and when A is a transition metal, the transition metal doping element is different from A. The transition metal doping element preferably includes Co, so as to further improve the adsorption effect of the adsorbent.

[0010] For example, the Prussian blue type base material can include K2MgFe(CN)6, K2Fe[Fe(CN)6], K2Co[Fe(CN)6], K2Ni[Fe(CN)6], K2Cu[Fe(CN)6], and the like, but is not limited thereto.

[0011] Further, the content of the transition metal doping element in the doped and modified Prussian blue analog is 0.5wt% to 5wt%.

[0012] Further, the preparation method of the doped and modified Prussian blue analog includes: reacting a mixed reaction system containing potassium ferrocyanide, an A ion source, and a transition metal doping element source at room temperature to 100°C to obtain the doped and modified Prussian blue analog, wherein the A ion source is used to provide A ions, and the A ions include at least one of Mg ions, Fe ions, Co ions, Ni ions, and Cu ions.

[0013] For example, the A ion source can include magnesium chloride, iron chloride, cobalt chloride, nickel chloride, copper chloride, and the like, but is not limited thereto.

[0014] For example, the preparation method of the doped and modified Prussian blue analog specifically includes: providing an A solution containing 0.01mol / L to 1.5mol / L of K4[Fe(CN)6]·3H2O, a B solution containing 0.01mol / L to 1.5mol / L of A ions, and a C solution containing 0.0001mol / L to 0.6mol / L of a transition metal doping element; mixing the B solution and the C solution to form a BC mixed solution, then adding the A solution into the BC mixed solution dropwise, controlling the reaction temperature at room temperature to 100°C, stopping stirring and standing for 0.1h to 12h after the BC mixed solution is completely added into the A solution, and reacting to obtain the doped and modified Prussian blue analog.

[0015] In some embodiments, the granulation specifically comprises: mixing the Prussian blue type material with a granulating agent and a first solvent to form a mixture, and dropping the mixture into water to obtain the granular rubidium-caesium adsorbent precursor. The granulated adsorbent after granulation has high mechanical strength and high compressive strength, and is suitable for fixed bed and adsorption tower adsorption process, and has good industrial applicability. The present application uses a new modified granulation technology, so that the powder material maintains high adsorption capacity after forming, and meets the requirements of column adsorption industrial application.

[0016] In some embodiments, the granulating agent comprises a polymer binder, which may, for example, comprise a combination of one or more of polyacrylonitrile (PAN), polyvinyl chloride (PVC), and polyvinylidene fluoride. In some preferred embodiments, the granulating agent comprises PAN and PVC. PVC has strong binding properties, but is relatively hydrophobic. Therefore, an appropriate amount of PAN can be introduced to not only increase the strength, but also provide hydrophilic groups, so that the three work together to maintain strength and not be too hydrophobic to reduce adsorption capacity. PVC and PAN may, for example, be mixed in a mass ratio of 1-8:1-2, and a mass ratio of 8:2 is preferred. If the amount of PAN is too large, granulation cannot be achieved.

[0017] In some embodiments, the mass of the Prussian blue type material used in the granulation is 70wt%-95wt% of the total mass of the Prussian blue type material and the granulating agent.

[0018] In some embodiments, the mass of the granulating agent used in the granulation is 5wt%-30wt% of the total mass of the Prussian blue type material and the granulating agent.

[0019] For example, in the granulation, the granulating agent is first dissolved in the first solvent to form a mixed solution, and then the Prussian blue type material is added to form the mixture. The mass-to-volume ratio of the Prussian blue type material to the mixed solution may, for example, be (1:1.7-2.3) g / ml.

[0020] In some embodiments, the first solvent may, for example, comprise any one or more of N-methylpyrrolidone, N,N-dimethylformamide (DMF), and N,N-dimethylacetamide (DMAc), but is not limited thereto.

[0021] In some embodiments, the reaction temperature of the mixed reaction system is room temperature to 60°C.

[0022] In some embodiments, the reaction time of the mixed reaction system is 0.5h-6h.

[0023] In some embodiments, the content of the rubidium-caesium adsorbent precursor in the mixed reaction system is 70wt%-95wt%.

[0024] In some embodiments, the content of the surface modifier in the mixed reaction system is 0.1wt%-5wt%.

[0025] In some embodiments, the surface modifier comprises one or a combination of ethylenediamine, polyethyleneimine, p-aminobenzenesulfonic acid, sodium p-aminobenzenesulfonate, glutamic acid, tris(hydroxymethyl)aminomethane, 4'-amino-benzo-15-crown-5, 2-aminomethyl-18-crown-6, 4'-amino-benzo-15-crown-5, 4'-amino-benzo-21-crown-7, KH-590, KH-550, KH-570, KH-792, A-174, A-1891, GPTMS-SH, 5-aminomethylcalix[4]arene-[bis-4-(2-ethylhexyl)benzocrown-6], aminated calix[4]arene bis(crown-6-ether), aminated calix[4]arene bis(crown-7-ether).

[0026] The crown ethers such as 4'-amino-benzo-15-crown-5, 2-aminomethyl-18-crown-6, 4'-amino-benzo-15-crown-5, 4'-amino-benzo-21-crown-7 can be used to provide crown ether structure; the structures of 5-aminomethylcalix[4]arene-[bis-4-(2-ethylhexyl)benzocrown-6], aminated calix[4]arene bis(crown-6-ether), aminated calix[4]arene bis(crown-7-ether) contain both calixarene structure and crown ether structure.

[0027] The surface modifier can modify the granulating agent in the granules obtained by granulation, and the granulating agent after surface modification introduces a functional group of robusium and cesium, so as to also have a certain adsorption effect of rubidium and cesium, that is, the prussian blue type material and the granulating agent realize synergistic adsorption, so as to improve the adsorption capacity and solve the problem of large loss of adsorption capacity caused by the existing granulation process. Specifically, the surface modifier containing the above-mentioned functional groups such as amino group, sulfonic acid group, carboxyl group, mercapto group, acryloxy group, and epoxy group can make the granulating agent robusium and cesium ions, and repel anions, thereby improving the selectivity; the surface modifier containing crown ether ring and cup structure can complex with rubidium and cesium ions, or only allow rubidium ions and cesium ions to pass through, thereby improving the selectivity.

[0028] In a typical embodiment, the preparation method of the rubidium and cesium adsorbent comprises: Mixing the prussian blue type material, the granulating agent, and the first solvent to form a mixture, and uniformly dropping the mixture into water to obtain a mixture containing granular rubidium and cesium adsorbent precursor; Adding the second solvent and the surface modifier to the mixture to form the mixed reaction system, and reacting at room temperature-60°C for 0.5h-6h.

[0029] For example, the second solvent includes one or more of water, methanol, and ethanol, but is not limited thereto.

[0030] The second aspect of the present application provides a rubidium and cesium adsorbent prepared by the preparation method of any one of the above technical solutions.

[0031] The third aspect of the present application provides the use of the rubidium and cesium adsorbent in adsorbing and recovering rubidium and cesium.

[0032] The fourth aspect of the present application provides a method for adsorbing and recovering rubidium and cesium, comprising: contacting the rubidium and cesium adsorbent of any one of the above technical solutions with a feed liquid containing rubidium and / or cesium to perform adsorption.

[0033] In some embodiments, after the adsorption is completed, the adsorbent adsorbed with rubidium and / or cesium is subjected to desorption treatment. The desorption treatment can use a solution containing nitric acid, ammonium chloride, and ammonium nitrate. After the desorption is completed, deionized water can be used to wash it to neutral. The rubidium and cesium adsorbent of the present application has good cycle stability and can be repeatedly used for multiple times.

[0034] In some embodiments, the feed liquid containing rubidium and / or cesium also contains potassium ions and / or sodium ions. The present application improves the selective adsorption capacity of the adsorbent to Rb + / Cs + by surface modification, and inhibits the competitive adsorption of K + , Na + , and thus it is particularly suitable for efficient recovery of low-concentration Rb + / Cs + under a high-sodium and high-potassium background, such as a high-potassium and high-concentration salt system with a rubidium and cesium ion concentration of 20 mg / L to 1 g / L.

[0035] In some embodiments, the feed liquid is a strong acidic feed liquid with a pH value of less than 3, or the feed liquid is a strong alkaline feed liquid with a pH value of more than 10.

[0036] In some embodiments, the feed liquid is a head ash leaching solution, a solid waste leaching solution, a salt lake brine, or radioactive waste water.

[0037] Compared with the prior art, the present application has at least the following beneficial effects: (1) The present application uses a surface modifier containing a specific functional group to perform surface grafting modification on the granulated adsorbent, thereby improving the specific recognition of the adsorbent to Cs + / Rb + and improving the selectivity of the adsorbent; (2) The preferred embodiment of the method provided by the present application obtains good stability, high adsorption capacity, and strong Rb + / Cs+ A granular rubidium-caesium adsorbent with selectivity and high mechanical strength. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments described in the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0039] Figure 1 is a flowchart of preparing the rubidium-caesium adsorbent in the embodiments of the present application; Figure 2a is a SEM image of the rubidium-caesium adsorbent in Example 9 of the present application; Figure 2b is a SEM image of the rubidium-caesium adsorbent in Example 9 of the present application after adsorbing Cs + Figure 2c is a TEM image of the rubidium-caesium adsorbent in Example 9 of the present application; Figure 2d is an EDS image of the rubidium-caesium adsorbent in Example 9 of the present application; Figure 2e is an EDS image of the rubidium-caesium adsorbent in Example 9 of the present application after adsorbing Cs + Figure 3 is a comparison chart of the adsorption performance of the rubidium-caesium adsorbent in Examples 1-9 of the present application; Figure 4 is a comparison chart of the adsorption performance of the rubidium-caesium adsorbent in Example 9 of the present application under different pH conditions, wherein the vertical coordinate adsorption capacity represents the adsorption capacity of the rubidium-caesium adsorbent for cesium in the solution corresponding to the pH value; Figure 5 is a chart of the cesium adsorption cycle of the rubidium-caesium adsorbent in Example 9 of the present application. DETAILED DESCRIPTION

[0040] The present application will be more fully understood from the following detailed description taken in connection with the accompanying drawings. Detailed embodiments of the present application are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the present application and can be embodied in various forms. Therefore, specific functional details disclosed herein are not to be interpreted as limiting, but only as a representative basis for teaching one skilled in the art to employ the present application in virtually any appropriate detailed embodiment. The present application is based on and claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 62 / 947, 1 10, filed December 14, 2019, the disclosure of which is incorporated by reference herein in its entirety.

[0041] ​​In addition, unless otherwise specified, the various raw materials used in the following examples can be obtained from the market or the like, and the various production and testing equipment used are known in the art, and the testing methods used are also known in the art.

[0042] Example 1 The present embodiment provides an Al-doped and polyethyleneimine-modified rubidium and cesium adsorbent and a preparation method thereof, Figure 1 is a schematic diagram of the preparation process of the present embodiment, which specifically comprises the following steps: (1) Take 63.4 g of K4[Fe(CN)6]·3H2O, add 300 ml of deionized water, stir uniformly to form a stable homogeneous solution A; take 30.6 g of MgCl2·6H2O, add 200 ml of deionized water, stir uniformly to form a stable homogeneous solution B; take 4 g of AlCl3·6H2O, add 50 ml of deionized water, stir uniformly to form a stable homogeneous solution C; (2) Mix solution B and solution C, then uniformly drop the obtained BC mixed solution into solution A, and continuously stir solution A, when the BC mixed solution is completely dropped into solution A, stop stirring and stand for 2 h, then filter with a Buchner funnel, continuously wash with deionized water, and dry at 60°C for standby, to obtain Al-doped K2MgFe(CN)6; (3) Dissolve 5 g of PAN and PVC respectively in 100 mL of N-methyl pyrrolidone, add 50 g of the above-prepared Al-doped K2MgFe(CN)6, stir uniformly to form a mixture, uniformly drop the mixture into deionized water to obtain a granulated rubidium and cesium adsorbent precursor; (4) Continue to add 100 ml of deionized water to the reaction product of step (3), and add 2 ml of polyethyleneimine, heat and oscillate at 60°C for 5 h to obtain an Al-doped and polyethyleneimine-modified granulated rubidium and cesium adsorbent, which has a large number of amino groups on the surface.

[0043] Example 2 The present embodiment provides an Al-doped and polyethyleneimine-modified rubidium and cesium adsorbent and a preparation method thereof, (1) Take 63.4 g of K4[Fe(CN)6]·3H2O, add 300 ml of deionized water, stir uniformly to form a stable homogeneous solution A; take 30.6 g of MgCl2·6H2O, add 200 ml of deionized water, stir uniformly to form a stable homogeneous solution B; take 4 g of AlCl3·6H2O, add 50 ml of deionized water, stir uniformly to form a stable homogeneous solution C; (2) mixing solution B and solution C, then dropping the obtained BC mixed solution into solution A at a constant speed, continuously stirring solution A, stopping stirring and standing for 2 h after the BC mixed solution is completely dropped into solution A, then filtering by using a Buchner funnel, continuously washing with deionized water, drying at 60°C for standby, obtaining Al-doped K2MgFe(CN)6; (3) respectively taking 5 g of PAN and PVC and dissolving them in 100 mL of N-methyl pyrrolidone, adding 50 g of the Al-doped K2MgFe(CN)6 prepared above, stirring to form a mixture, dropping the mixture into deionized water at a constant speed, and obtaining a granulated rubidium-caesium adsorbent precursor; (4) continuously adding 100 ml of deionized water to the reaction product of step (3), and adding 2 ml of ethylenediamine, heating and oscillating at 60°C for 5 h, and obtaining an Al-doped and ethylenediamine-modified granulated rubidium-caesium adsorbent, which has a large number of amino groups on the surface.

[0044] Example 3 The present embodiment provides an Al-doped and 2-aminoethanesulfonic acid-modified rubidium-caesium adsorbent and a preparation method thereof, specifically comprising the following steps: (1) taking 63.4 g of K4[Fe(CN)6]·3H2O, adding 300 ml of deionized water, stirring to form a stable homogeneous solution A; taking 30.6 g of MgCl2·6H2O, adding 200 ml of deionized water, stirring to form a stable homogeneous solution B; taking 4 g of AlCl3·6H2O, adding 50 ml of deionized water, and stirring to form a stable homogeneous solution C; (2) mixing solution B and solution C, then dropping the obtained BC mixed solution into solution A at a constant speed, continuously stirring solution A, stopping stirring and standing for 2 h after the BC mixed solution is completely dropped into solution A, then filtering by using a Buchner funnel, continuously washing with deionized water, and drying at 60°C for standby, obtaining Al-doped K2MgFe(CN)6; (3) respectively taking 5 g of PAN and PVC and dissolving them in 100 mL of N-methyl pyrrolidone, adding 50 g of the Al-doped K2MgFe(CN)6 prepared above, stirring to form a mixture, dropping the mixture into deionized water at a constant speed, and obtaining a granulated rubidium-caesium adsorbent precursor; (4) continuously adding 100 ml of deionized water to the reaction product of step (3), and adding 2 ml of 2-aminoethanesulfonic acid, heating and oscillating at 60°C for 5 h, and obtaining an Al-doped and 2-aminoethanesulfonic acid-modified granulated rubidium-caesium adsorbent, which has a large number of sulfonic acid groups on the surface.

[0045] Example 4 The embodiment provides a Co-doped and 2-aminoethanesulfonic acid modified rubidium and cesium adsorbent and a preparation method thereof, and specifically comprises the following steps. (1) 63.4 g of K4[Fe(CN)6]·3H2O is taken, 300 ml of deionized water is added, and a stable homogeneous solution A is formed after uniform stirring; 30.6 g of MgCl2·6H2O is taken, 200 ml of deionized water is added, and a stable homogeneous solution B is formed after uniform stirring; 4 g of CoCl3·6H2O is taken, 50 ml of deionized water is added, and a stable homogeneous solution C is formed after uniform stirring; (2) solution B and solution C are mixed, then the obtained BC mixed solution is uniformly dropped into solution A, and solution A is continuously stirred, when the BC mixed solution is completely dropped into solution A, the stirring is stopped and the solution is left still for 2 h, then the solution is filtered by using a Buchner funnel, and is continuously washed with deionized water, and is dried at 60℃ for standby, to obtain Co-doped K2MgFe(CN)6; (3) 5 g of PAN and PVC are respectively taken and dissolved in 100 mL of N-methyl pyrrolidone, 50 g of the prepared Co-doped K2MgFe(CN)6 is added, and the mixture is uniformly stirred to form a mixed material, and the mixed material is uniformly dropped into deionized water to obtain a granulated rubidium and cesium adsorbent precursor; (4) 100 ml of deionized water is continuously added to the reaction product of step (3), and 2 ml of 2-aminoethanesulfonic acid is added, and the mixture is heated and oscillated at 60℃ for 5 h, to obtain a Co-doped and 2-aminoethanesulfonic acid modified granulated rubidium and cesium adsorbent, and the surface of the adsorbent contains a large number of sulfonic acid groups.

[0046] Embodiment 5 The embodiment provides a Cu-doped and 2-aminoethanesulfonic acid modified rubidium and cesium adsorbent and a preparation method thereof, and specifically comprises the following steps. (1) 63.4 g of K4[Fe(CN)6]·3H2O is taken, 300 ml of deionized water is added, and a stable homogeneous solution A is formed after uniform stirring; 30.6 g of MgCl2·6H2O is taken, 200 ml of deionized water is added, and a stable homogeneous solution B is formed after uniform stirring; 4 g of CuCl2·6H2O is taken, 50 ml of deionized water is added, and a stable homogeneous solution C is formed after uniform stirring; (2) solution B and solution C are mixed, then the obtained BC mixed solution is uniformly dropped into solution A, and solution A is continuously stirred, when the BC mixed solution is completely dropped into solution A, the stirring is stopped and the solution is left still for 2 h, then the solution is filtered by using a Buchner funnel, and is continuously washed with deionized water, and is dried at 60℃ for standby, to obtain Cu-doped K2MgFe(CN)6; (3) 5 g of PAN and 5 g of PVC were dissolved in 100 mL of N-methyl pyrrolidone, 50 g of the K2MgFe(CN)6 doped with Cu prepared above was added, and the mixture was stirred to form a mixture, and the mixture was dropped into deionized water at a constant speed to obtain a granulated rubidium-caesium adsorbent precursor; (4) 100 ml of deionized water and 2 ml of 2-aminoethanesulfonic acid were added to the reaction product of step (3), and the mixture was heated and shaken at 60°C for 5 h to obtain a Cu-doped and 2-aminoethanesulfonic acid-modified granulated rubidium-caesium adsorbent, and the surface of the adsorbent contained a large number of sulfonic acid groups.

[0047] Example 6 The present embodiment provides a Mn-doped and 4'-amino-benzo-15-crown-5-modified rubidium-caesium adsorbent and a preparation method thereof, and specifically comprises the following steps: (1) 63.4 g of K4[Fe(CN)6]·3H2O was dissolved in 300 ml of water to obtain a solution A; 30.6 g of MgCl2·6H2O and 4 g of MnCl2·6H2O were dissolved in 250 ml of water to obtain a mixed solution B; (2) Solution B was added to solution A, and the mixture was stirred and reacted for 2 h, and then filtered, washed and dried at 60°C to obtain K2MgFe(CN)6 doped with Mn; (3) 5 g of PAN and 5 g of PVC were dissolved in 100 mL of N-methyl pyrrolidone, 50 g of the K2MgFe(CN)6 doped with Mn prepared above was added, and the mixture was stirred to form a mixture, and the mixture was dropped into deionized water at a constant speed to obtain a granulated rubidium-caesium adsorbent precursor; (4) 100 ml of an aqueous solution containing 2 g of 4'-amino-benzo-15-crown-5 was added to the reaction product of step (3), and the mixture was modified at 60°C for 5 h to obtain a Mn-doped and 4'-amino-benzo-15-crown-5-modified rubidium-caesium adsorbent.

[0048] Example 7 Example 7 is basically the same as Example 1, except that ZrCl4·6H2O is used instead of AlCl3·6H2O in step (1) of Example 1, and 2 g of sodium p-aminobenzenesulfonate is used instead of 2 ml of polyethyleneimine in step (4) of Example 1, and the rest is the same as Example 1, which will not be repeated here. A Zr-doped and sodium p-aminobenzenesulfonate-modified rubidium-caesium adsorbent was prepared.

[0049] Example 8 Example 8 is substantially the same as Example 1, except that in step (1), 2 g of ZnCl2and 2 g of NiCl2are used instead of 4 g of AlCl3·6H2O in Example 1; in step (4), 1.5 g of 2-aminomethyl-18-crown-6 is used instead of 2 ml of polyethyleneimine in Example 1, and the rest is the same as Example 1, which is not repeated here.

[0050] Example 9 Example 9 is different from Example 1 in that Example 9 does not perform Al doping, and an undoped but polyethyleneimine modified rubidium and cesium adsorbent is prepared, and the rest is the same as Example 1, which is not repeated here.

[0051] Example 10 Steps (1), (2), and (3) are exactly the same as Example 1; Step (4): 100 ml of deionized water and ethanol solution (1:1 mixture) and 2 g of 5-aminomethyl calix[4]arene-[bis-4-(2-ethylhexyl) benzo crown-6] are further added to the reaction product of step (3), and heated and shaken at 60°C for 5 h to obtain an Al-doped and 5-aminomethyl calix[4]arene-[bis-4-(2-ethylhexyl) benzo crown-6] modified granulated rubidium and cesium adsorbent, which contains a large number of crown groups on the surface.

[0052] Example 11 Example 11 is different from Example 4 in that Example 11 does not perform Co doping, and an undoped but 2-aminoethanesulfonic acid modified rubidium and cesium adsorbent is prepared, and the rest is the same as Example 4, which is not repeated here.

[0053] Example 12 Example 12 is different from Example 8 in that Example 12 does not perform Zn / Ni doping, and an undoped but 2-aminomethyl-18-crown-6 modified rubidium and cesium adsorbent is prepared, and the rest is the same as Example 8, which is not repeated here.

[0054] Example 13 Example 13 is substantially the same as Example 1, except that: In step (3), the amount of granulating agent used in granulation is 5 wt% of the total mass of Al-doped K2MgFe(CN)6and granulating agent, and the granulating agent is PVC and PAN in a mass ratio of 1:1; In step (4), the polyethyleneimine added is 0.1 wt%.

[0055] The rest is the same as Example 1, which is not repeated here.

[0056] Example 14 Example 14 is substantially the same as Example 1, except that: In step (3), the amount of granulating agent is 30wt% of the total mass of Al-doped K2MgFe(CN)6 and the granulating agent, and the granulating agent is PVC and PAN in a mass ratio of 1:1; In step (4), the polyethyleneimine added is 5wt%.

[0057] The rest is the same as Example 1, which will not be repeated here.

[0058] Comparative Example 1 Comparative Example 1 is different from Example 1 only in that Comparative Example 1 is not modified by polyethyleneimine, and an Al-doped rubidium and cesium adsorbent without polyethyleneimine modification is prepared, and the rest is the same as Example 1, which will not be repeated here.

[0059] Comparative Example 2 Comparative Example 2 is different from Example 4 only in that Comparative Example 2 is not modified by 2-aminoethanesulfonic acid, and a Co-doped rubidium and cesium adsorbent without 2-aminoethanesulfonic acid modification is prepared, and the rest is the same as Example 4, which will not be repeated here.

[0060] Comparative Example 3 Comparative Example 3 is different from Example 8 in that Comparative Example 3 is not modified by 2-aminomethyl-18-crown-6, and a Zn / Ni-doped rubidium and cesium adsorbent without 4'-aminobenzo-15-crown-5 modification is prepared, and the rest is the same as Example 8, which will not be repeated here.

[0061] Comparative Example 4 Comparative Example 4 is different from Example 1 only in that Comparative Example 4 does not perform the granulation process of step (3), but directly modifies the powder adsorbent precursor with the same amount of polyethyleneimine as Example 1. However, it is found that direct modification of the powder cannot occur chemical reaction, and there is no functional group on the surface of the powder after the same modification treatment.

[0062] Figure 2a is the SEM image of the rubidium and cesium adsorbent in Example 9 of the application; Figure 2b is the SEM image of the rubidium and cesium adsorbent in Example 9 of the application after adsorbing Cs + ; Figure 2c is the TEM image of the rubidium and cesium adsorbent in Example 9 of the application; Figure 2d is the EDS image of the rubidium and cesium adsorbent in Example 9 of the application; Figure 2e is the EDS image of the rubidium and cesium adsorbent in Example 9 of the application after adsorbing Cs + ; Figure 2a , Figure 2bIt can be seen that the surface of the adsorbent is rough, which is beneficial to the adsorption of cesium, and the morphology of the adsorbent before and after adsorption changes little; from Figure 2c It can be seen that the crystal lattice stripes of the adsorbent are clear and visible, and the interplanar spacing is 0.3445 nm. Figure 2d It is shown that the adsorbent before adsorption contains K, Mg, Fe, C and N elements, and the adsorbent after adsorption contains K, Mg, Fe, C, N and Cs elements, which indicates that the adsorbent can effectively adsorb Cs + .

[0063] The rubidium and cesium adsorbents prepared in the above examples and comparative examples were added into a rubidium and cesium solution with a rubidium concentration of 500 mg / L and a cesium concentration of 500 mg / L, and were placed in a sealed plastic bottle, and the temperature was controlled at 25℃ for adsorption experiment. After reaching adsorption equilibrium, the supernatant was taken to the scale, and the concentration was measured using ICP-OES. The absorption capacity was calculated according to the concentration difference before and after adsorption, and the results are shown in Table 1.

[0064] Figure 3 is the adsorption performance comparison chart of the rubidium and cesium adsorbents in examples 1-9 of the present application.

[0065] Table 1

[0066] As can be seen from Table 1, the rubidium and cesium adsorbents prepared based on the method of the present application have high adsorption capacity. It needs to be particularly pointed out that, by comparing example 1 and comparative example 4, it is found that the adsorption capacity of the adsorbent treated by granulation in example 1 is basically equivalent to that of comparative example 4, which indicates that the granulation method adopted in the present application will not cause significant reduction of the adsorption capacity, and the mechanical strength of the granular adsorbent obtained by granulation is significantly higher than that of the powdery adsorbent of comparative example 4, so that it can be used in industrial fixed bed, adsorption tower and other adsorption processes.

[0067] Moreover, doping the Prussian blue type material can also improve the strength of the adsorbent after granulation. The compressive strength of the adsorbent without doping in example 11 is 5.8 N, and the compressive strength of the Co-doped adsorbent in example 4 is 8.3 N.

[0068] The stability of the rubidium and cesium adsorbents prepared in the above examples and comparative examples in strong acid and strong alkali environment was also tested, and the specific method is as follows: Solutions with pH values of 2-12 and containing rubidium ions and cesium ions with a concentration of 500 mg / L were prepared respectively, and the rubidium and cesium adsorbents prepared in the above examples and comparative examples were placed in the rubidium and cesium solutions with pH values of 2-12 for adsorption. After reaching adsorption equilibrium, the adsorption effect was tested.

[0069] Figure 4is a comparison chart of the cesium adsorption performance of the rubidium and cesium adsorbent of embodiment 9 under different pH conditions, Figure 4 The middle ordinate adsorption capacity represents the adsorption capacity of the rubidium and cesium adsorbent for cesium ions in a solution corresponding to the pH value. From the comparison chart of the cesium adsorption performance of the rubidium and cesium adsorbent of embodiment 9 under different pH conditions, Figure 4 It can be seen that the rubidium and cesium adsorbent of embodiment 9 maintains stable adsorption effect in acidic, neutral and alkaline environments.

[0070] The rubidium and cesium adsorbent of embodiment 1 and embodiment 9 was also tested for the dissolution loss rate, and it was found that the adsorbent doped with Al in embodiment 1 had a lower dissolution loss rate and a higher adsorption capacity. After 20 cycles of adsorption, the Fe dissolution loss of the rubidium and cesium adsorbent of embodiment 1 was 0.01%, while the Fe dissolution loss of the rubidium and cesium adsorbent of embodiment 9 was 0.5%. This is because the doping of transition metal ions can further improve the skeleton stability of the adsorbent in strong acid and strong alkali environments, reduce the skeleton collapse and metal ion dissolution, and improve the adsorption capacity, so that it is applicable in environments with a pH value of 2-12. Similarly, the Fe dissolution loss rates of the doped and modified adsorbents of embodiments 1-8 were also tested by the same method, and the Fe dissolution loss rates were all less than 0.01%, and the structures of the adsorbents in strong acid and strong alkali environments were more stable.

[0071] The cycle stability of the rubidium and cesium adsorbent prepared by the present application was also tested, and the test method was as follows: The rubidium and cesium adsorbent of embodiment 9 was placed in a solution containing 500 mg / L of rubidium and cesium, and adsorption was carried out at room temperature. After reaching adsorption equilibrium, the supernatant was taken to the scale, and the concentration was measured by ICP-OES. The adsorption capacity was calculated according to the concentration difference before and after adsorption. Then, the saturated adsorbent was washed with water, and rubidium and cesium ions were desorbed by using a 10% concentration of ammonium nitrate solution. After complete desorption, the adsorbent was washed with deionized water and neutralized to neutral. The above steps were repeated to test the cycle performance.

[0072] Figure 5 is a cycle chart of the cesium adsorption of the rubidium and cesium adsorbent of embodiment 9, and the adsorption effect of the rubidium and cesium adsorbent on cesium is stable during 5 cycles, which indicates that the rubidium and cesium adsorbent prepared by the present application has good cycle stability.

[0073] The rubidium and cesium adsorbents of embodiments 1, 4 and 8 were also used to adsorb rubidium and cesium in a high-concentration potassium ion solution (136 g / L of potassium ions), and the removal rate of the rubidium and cesium was more than 95%. Compared with the three embodiments, the adsorbents of comparative examples 1-3 without surface modification had a removal rate of rubidium and cesium of about 89% in the complex environment. This indicates that the rubidium and cesium adsorbent of the present application can preferentially recognize Cs + , Rb +, and is resistant to potassium ion interference, so it is particularly suitable for adsorbing low-concentration rubidium and cesium in high-potassium solutions, and has good application prospects in complex environments such as head gray leaching solution, solid waste leaching solution, salt lake brine and radioactive wastewater.

[0074] In addition, the present inventors have also carried out tests on other raw materials, process operations and process conditions described in the specification with reference to the foregoing examples, and the prepared rubidium and cesium adsorbents all have good adsorption capacity, skeleton stability, excellent Rb + / Cs + selectivity and mechanical strength.

[0075] In summary, the present application improves the selectivity of Rb + / Cs + by surface grafting surface modifiers with sulfonic acid groups, amino groups, crown ether and other functional groups; and the adsorbent is endowed with excellent mechanical strength by the granulation molding process, and can be directly used for industrial column operation; and the adsorbent provided by the present application exhibits high adsorption capacity and good cycle life, and is particularly suitable for efficient recovery of low-concentration Rb + / Cs + under high potassium background. Further, the skeleton stability of the Prussian blue analogue is enhanced by transition metal doping to reduce the dissolution rate, so that the prepared rubidium and cesium adsorbent has a wide pH range of application, and still maintains structural integrity in strong acid and strong alkaline solutions. The preparation method provided by the present application is simple and low in cost.

[0076] Aspects, embodiments, features, and examples of the present application should be considered illustrative, for explanation, illustration, but not for limiting the present application, the scope of the present application is only defined by the claims.

[0077] Although the present application has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions and / or additions can be made and elements of the described embodiments can be substituted with substantial equivalents without departing from the spirit and scope of the present application. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the present application without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the disclosed specific embodiments for carrying out the present application, but is intended to encompass all embodiments falling within the scope of the appended claims.

Claims

1. A method for producing a rubidium and cesium adsorbent, characterized by, The method comprises: granulating a mixture containing a Prussian blue material and a granulating agent to obtain a rubidium and cesium adsorbent precursor; reacting a mixed reaction system containing the rubidium and cesium adsorbent precursor and a surface modifier to obtain a rubidium and cesium adsorbent, wherein the surface modifier contains a functional structure of one or more of an amino group, a sulfonic acid group, a carboxyl group, a mercapto group, an acryloyloxy group, an epoxy group, a crown ether structure, and a calixarene structure.

2. The method of claim 1, wherein: The Prussian blue material is a doped and modified Prussian blue analogue, which comprises a Prussian blue base material and a transition metal doping element doped therein.

3. The method of claim 2, wherein: The Prussian blue base material has a chemical formula of K2A[Fe(CN)6], wherein A comprises one or more of Mg, Fe, Co, Ni, and Cu, the transition metal doping element comprises one or more of Al, Co, Mn, Zr, Zn, Cu, and Ni, and when A is a transition metal, the transition metal doping element is different from A. The content of the transition metal doping element in the doped and modified Prussian blue analogue is 0.5wt%-5wt%.

4. The method of claim 1, wherein, The granulation specifically comprises: mixing the Prussian blue material, a granulating agent, and a first solvent to form a mixture, and dropping the mixture into water to obtain the granular rubidium and cesium adsorbent precursor.

5. The production method according to claim 1 or 4, characterized by: The granulating agent comprises one or more of a combination of polyacrylonitrile, polyvinyl chloride, and polyvinylidene fluoride. The mass of the Prussian blue material used in the granulation is 70wt%-95wt% of the total mass of the Prussian blue material and the granulating agent. The mass of the granulating agent used in the granulation is 5wt%-30wt% of the total mass of the Prussian blue material and the granulating agent.

6. The method of claim 1, wherein: The reaction temperature of the mixed reaction system is normal temperature-60°C, and / or the reaction time of the mixed reaction system is 0.5h-6h.

7. The method of claim 1, wherein: The content of the rubidium and cesium adsorbent precursor in the mixed reaction system is 70wt%-95wt%. The content of the surface modifier in the mixed reaction system is 0.1wt%-5wt%. The surface modifier comprises one or more of a combination of ethylenediamine, polyethyleneimine, 2-aminoethanesulfonic acid, p-aminobenzenesulfonic acid, sodium p-aminobenzenesulfonate, glutamic acid, tris(hydroxymethyl)aminomethane, 4'-amino-benzo-15-crown-5, 2-aminomethyl-18-crown-6, 4'-amino-benzo-15-crown-5, 4'-amino-benzo-21-crown-7, KH-590, KH-550, KH-570, KH-792, A-174, A-1891, GPTMS-SH, 5-aminomethylcalix[4]arene-[bis-4-(2-ethylhexyl)benzocrown-6], aminated calix[4]arene bis(crown-6-ether), and aminated calix[4]arene bis(crown-7-ether).

8. A rubidium and cesium adsorbent characterized by, The rubidium and cesium adsorbent is prepared by the preparation method of any one of claims 1-7.

9. The rubidium and cesium adsorbent of claim 8 is used for adsorbing and recovering rubidium and cesium.

10. A method for recovering rubidium and cesium by adsorption, characterized by, The method comprises: contacting the rubidium and cesium adsorbent of claim 8 with a feed solution containing rubidium and / or cesium to adsorb; Preferably, the feed solution further contains potassium ions and / or sodium ions; Preferably, the feed solution is a strongly acidic feed solution with a pH value of 3 or less, or the feed solution is a strongly alkaline feed solution with a pH value of 10 or more; Preferably, the feed solution is a head-ash leaching solution, a solid waste leaching solution, a salt lake brine or a radioactive waste water.

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