A highly selective Cs + Ion exchangers, process for their preparation and use

Abstract

The application is a high-selectivity Cs + Ion exchanger and its preparation method and application. The molecular formula of the ion exchanger is (CH3NH3)Na2Sb9S 15 ·3.5H2O; the preparation is carried out in a ternary mixed solvent composed of methylamine hydrochloride, N,N'-dimethylurea and hydrazine hydrate, an ammonium / methylamine / water molecular mixed template agent is generated in situ, and the assembly of antimony and sulfur atoms is cooperatively induced, so that an inorganic molecular sheet compound with an elliptical pore cavity is synthesized, and then the inorganic molecular sheet compound is subjected to Na + Ion substitution and activation on the template to prepare (CH3NH3)Na2Sb9S 15 ·3.5H2O (Na-SbS) ion exchanger. The exchanger in the application can selectively capture Cs + Ions from a complex solution containing multiple coexisting ions, and has the characteristics of fast adsorption rate, easy elution and radiation resistance.

Description

Technical fields:

[0001] This invention belongs to the field of cesium water treatment, specifically relating to a method for treating Cs in complex acidic water environments where numerous competing ions exist. + Ion exchangers with ultra-high selectivity, their preparation methods, and their applications. Background technology:

[0002] Enrichment and recovery of fission isotopes produced by nuclear cycles 137 Cs(t 1 / 2 =30.2 years) Not only is it beneficial for the safe handling and disposal of high-level radioactive waste liquids and the promotion of sustainable development of nuclear energy, but more importantly, it can turn waste into treasure and realize the comprehensive utilization value of isotopes. On the one hand, 137 Cs is present in relatively high concentrations in high-level radioactive waste (approximately 0.03-0.04 mol / L). -1 ), often in Cs + It exists in a form that is highly mobile, and its decay process can release a large amount of radiation (E). γ =661keV) and heat, making deep geological burial processes require larger geological treatment spaces. 137 Separating Cs can effectively reduce the heat release of high-level radioactive waste, increase the capacity of disposal facilities, and eliminate safety hazards during long-term storage (Energies, 2019, 12, 596-618). On the other hand, a sudden nuclear accident could release a large amount of radioactive material. 137 The leakage of Cs isotopes led to their significant accumulation in plants and animals in the surrounding area (Transactions of the Chinese Society of Agricultural Engineering, 2020, 36, 221-227; Nuclear Chemistry and Radiochemistry, 2015, 37, 341-354). 137 Cs can be transferred through the food chain and accumulate in the human body, causing cell / soft tissue damage or death, and inducing vomiting or other mental disorders (J. Environ. Chem. Eng., 2018, 6, 5845-5854). Through rapid capture... 137 Using Cs to block its spread is beneficial to improving the effectiveness of nuclear pollution control and effectively protecting environmental safety and public health. (Extracted) 137 After purification, Cs can be used to prepare lightweight, reliable, and durable nuclear batteries, which are widely applicable to instruments and equipment that require long-term power supply (such as communication satellites, spacecraft, submarines, etc.) and have important value in national defense science and technology and people's livelihood economy (Nuclear Chemistry and Radiochemistry, 2019, 41, 27-39). 137Cs can also be used to create gamma radiation sources for numerous technological and medical applications, including thickness measurement, nuclear radiation weighing, irradiation breeding, instrument sterilization, and cancer treatment (Open Geosciences, 2020, 12, 11-24; Sci. Total Environ., 2019, 651, 250-260; J. Radiat. Res. Appl. Sci. 2015, 8, 477-482). Therefore, selective extraction of fission isotopes... 137 Cs is a crucial component for the efficient recovery of useful substances and the realization of closed-loop recycling of waste liquid.

[0003] Ion exchange has the advantages of simple operation, easy automation, and good decontamination and purification effect, making it a good method for enriching radioactive substances in water. 137 Cs + Important methods (Solvent Extr. Ion Exch., 2000, 18, 655-678; Molecules, 2023, 28, 1935; Int. J. Environ. Res. Public Health, 2022, 19, 10183). However, apart from 137 Cs + In addition, high-level radioactive waste and nuclear-contaminated water usually contain large amounts of other ions, which can... 137 Cs + The enrichment of these ions creates competition or interference, which brings many difficulties to the purification of nuclides. These ions mainly include the following three categories: (1) Hundreds of radioactive isotopes produced by reactor operation, such as representative fission products. 90 Sr、 99 Tc (Coord. Chem. Rev., 2021, 427, 213473), neutron-activated product 60 Co、 63 Ni (Environ. Sci. Pollut. Res., 2020, 27, 6824-6836), rare earth element 144 Ce、 147 Pm et al. (J. Chromatogr. A, 2017, 1499, 1-20); (2) Alkali (earth) metal ions introduced during precipitation, flocculation, and extraction, such as Na + K + Mg 2+ Ca 2+ (J. Phys. Chem. C, 2017, 121, 10594-10608; Molecules, 2023, 28, 1935); (3) High-level radioactive waste liquid generated from spent fuel reprocessing also contains high concentrations of H2. +(Nat. Commun., 2022, 13, 658; J. Am. Chem. Soc., 2017, 139, 16494-16497). High-energy irradiation and heat release from radioactive nuclides can damage the structure of organic ion exchange resins, leading to material deactivation and decomposition (Chem. Sci., 2016, 7, 4804-4824). In contrast, although inorganic ion exchangers such as zeolites, clays, and titaniasilicates have better heat and radiation resistance, their Cs... + However, the exchange performance is easily affected by the salinity and acidity of the environment, leading to material deactivation, deterioration, pulverization, or even dissolution (Solvent Extr. Ion Exch. 2000, 18, 655-678). Therefore, there is an urgent need to develop a highly selective ion exchanger to achieve high selectivity under harsh conditions such as high acidity, high salinity, and coexistence of multiple radioactive isotopes. 137 Cs + Efficient enrichment and separation.

[0004] Thioantimonate materials, composed of an antimony-sulfur anionic framework and countercations, typically exhibit good acid and alkali stability and are a promising class of ion exchangers for practical applications, currently under research. Chinese invention patent CN114669269B discloses a Cs... + 、Sr 2+ A dual-function potassium antimony thioate ion exchanger, K₂Sb₄S₇·2H₂O, is produced under hypoeutectic solvothermal conditions using a single NH₄⁺ ion. + Template agent-induced formation, followed by K + Prepared through ion activation, the material exhibits a simple chain-like anionic arrangement. However, this material has the following limitations: the pores between the molecular chains are large and irregular, lacking specific and precise adsorption sites; therefore, the K+ filling these pores... + Ions can react with Cs + 、Sr 2 + Na + Ca 2+ It exchanges multiple ions, has low selectivity, and its adsorption behavior is easily affected by H+ in the solution. + The influence of this factor prevents the material from selectively separating and extracting Cs. + ion. Summary of the Invention:

[0005] The purpose of this invention is to overcome the effects of radioactive isotope ions, alkali (earth) metal ions, and H+ in nuclear wastewater and nuclear-contaminated water. + The interference effect of Cs provides a way to... +This paper presents a highly selective ion exchanger, its preparation method, and its applications. The ion exchanger utilizes a structure-directing effect of a mixed template agent to construct and crystallize an exchanger framework with specific adsorption sites. Preparation is carried out in a ternary mixed solvent consisting of methylamine hydrochloride, N,N'-dimethylurea, and hydrazine hydrate. An in-situ generated ammonium / methylamine / water molecule mixed template agent is used to synergistically induce the assembly of antimony and sulfur atoms, synthesizing an inorganic molecular sheet compound with elliptical cavities. This is then further processed by hydration of Na+. + Ions were used to substitute and activate the template agent to prepare (CH3NH3)Na2Sb9S, which can be mass-produced. 15 • 3.5H₂O (denoted as Na-SbS) ion exchanger. Na-SbS [Sb₉S] 15 ] n 3n- The elliptical cavities unique to Cs layers + It provides highly matched adsorption sites, filling the pores with hydrated Na. + The ions can react with Cs with high selectivity. + Ion exchange occurs. Even in highly acidic media (pH=2), Na-SbS can resist Sr. 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ Eu 3+ Na + K + Mg 2+ Ca 2+ Despite the influence of numerous coexisting cations (removal rates all below 10%), Cs were precisely enriched and separated. + Ions (removal rate all above 94%). Na-SbS also features fast adsorption rate, convenient elution, and radiation resistance.

[0006] The technical solution of the present invention is as follows:

[0007] A highly selective Cs + Ion exchanger, the molecular formula of which is: (CH3NH3)Na2Sb9S 15 ·3.5H2O;

[0008] In the aforementioned exchanger, each Sb atom is coordinated by three S atoms to form a {SbS3} trigonal pyramidal unit. Three {SbS3} units are connected at common angles to form a {Sb3S6} cluster. The {Sb3S6} cluster is alternately connected to Sb atoms to form a {Sb4S6} chain. Two adjacent chains are connected by {SbS3} bridging groups to form a ribbon-like {Sb9S} chain. 15}, and form a 10-membered ring {Sb10 S 10 The elliptical cavity of} contains hydrated Na + The ions, acting as counter cations, fill the central positions on both sides of the elliptical cavity, forming Cs. + Provides highly selective adsorption sites;

[0009] The bands are arranged in parallel and connected by Sb···S weak interactions to form a two-dimensional [Sb9S] band. 15 ] n 3n- Anion plates together construct the Na-SbS crystal lattice structure.

[0010] The highly selective Cs + A method for preparing an ion exchanger, comprising the following steps:

[0011] (1) Add methylamine hydrochloride, N,N'-dimethylurea, and hydrazine hydrate (98%) to a reaction vessel and stir to form a mixed solvent. Then add antimony powder and sulfur powder, stir evenly, and react at 150-200℃ for 2-5 days. Allow to cool naturally, wash with water 1-3 times, and dry to obtain the crystalline precursor (NH4). 0.5 (CH3NH3) 2.5 Sb9S 15 ·0.5H2O (denoted as SbS);

[0012] The molar ratios are: methylamine hydrochloride: N,N'-dimethylurea = 1:1-3; hydrazine hydrate (98%): N,N'-dimethylurea = 1:1-3; antimony powder: sulfur powder: methylamine hydrochloride = 1:1-5:4-10.

[0013] (2) Soak the crystal precursor in a 0.3-3M NaCl aqueous solution, stir at 70-90℃ for 2-24h, filter, wash with water 3-5 times, and air dry to obtain Na-SbS ion exchanger.

[0014] The mass percentage concentration of the hydrazine hydrate is 98%.

[0015] The highly selective Cs + Ion exchangers are used to enrich Cs from acidic solutions containing multiple coexisting metal ions. + ion.

[0016] Specifically, one of the following three methods:

[0017] Method 1, batch adsorption, includes the following steps:

[0018] The ion exchanger was added to the solution to be treated and stirred for 0.5 min to 12 h to complete the Cs process. + Adsorption of ions;

[0019] The solution to be treated contains Cs + Cs ions + The concentration range of the ions is 0.2-8000 ppm;

[0020] In the adsorption method described above, the ratio of solution volume to exchanger mass is 100-2000 mL / g. -1 ;

[0021] The pH of the solution to be treated is 0-12;

[0022] Alternatively, method two, ion exchange column adsorption, includes the following steps:

[0023] The aforementioned ion exchanger is added as a stationary phase to the chromatography column, and the solution to be treated flows through the column to complete the removal of Cs. + Adsorption of ions;

[0024] The volume of the packed exchanger stationary phase is 0.5-50 cm³. 3 ;

[0025] per 1cm 3 The flow rate of the stationary phase treatment solution is 0.1-20 mL / min. -1 ;

[0026] The solution to be treated contains Cs + Cs ions + The concentration range of the ions is 0.2-8000 ppm;

[0027] The pH of the solution to be treated is 0-12;

[0028] Alternatively, method three, microporous membrane adsorption, includes the following steps:

[0029] The above-mentioned ion exchanger was ball-milled and then mixed with an N-methylpyrrolidone solution of polyvinylidene fluoride. The mixture was stirred for 5-60 minutes to obtain a homogeneous slurry. This slurry was then uniformly coated onto the surface of an aqueous PTFE microporous filter membrane substrate with a thickness of 30-200 μm and allowed to air dry naturally for 3-50 hours to prepare a Na-SbS / PTFE microporous filter membrane. The solution to be treated was then rapidly passed through the prepared microporous filter membrane using vacuum filtration to complete the treatment of Cs. + Adsorption of ions.

[0030] The particle size of the ion exchanger after ball milling is 0.5-20 μm;

[0031] The mass ratio of ion exchanger to polyvinylidene fluoride is 5-50:1;

[0032] The concentration of N-methylpyrrolidone solution of polyvinylidene fluoride is 10-100 mg / mL. -1 ;

[0033] In the Na-SbS / PTFE microporous filter membrane, the thickness of the Na-SbS exchanger layer is 20-200 μm;

[0034] per 1cm 2 The flow rate of the solution treated by the Na-SbS / PTFE microporous membrane was 0.2-3 mL / min. -1 ;

[0035] The solution to be treated contains Cs + Cs ions + The concentration range of the ions is 0.2-8000 ppm;

[0036] The pH of the solution to be treated is 0-12;

[0037] Methods 1, 2, and 3 are described below.

[0038] The solution to be treated also contains coexisting ions Sr 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ Eu 3+ Na + K + Mg 2+ Ca 2+ One or more of the following; the concentration range of each ion is 0-20000ppm; when the content of the element is 0, it means that the element is not present.

[0039] The solution to be treated is radioactive wastewater, or a mixture of one or more of deionized water, lake water, tap water, and seawater containing Cs. + Ionic solutions.

[0040] Optionally, the exchanger adsorbs Cs by method one. + Then, immerse in a 1-3M NaCl solution and stir for 5-24 hours to complete the elution. After elution, remove, wash, dry, and reuse.

[0041] Optionally, the exchanger adsorbs Cs using method two. + After ionization, elution is completed by continuously pumping 1-3M NaCl solution through the exchange column, and the column can be reused.

[0042] Optionally, the exchanger adsorbs Cs via method three. +After ionization, a 1-3M NaCl solution is continuously filtered under reduced pressure through a Na-SbS / PTFE microporous membrane to complete elution, allowing for reuse.

[0043] The essential features of this invention are:

[0044] Previously reported inorganic Cs + Ion exchangers are often susceptible to interference from solution acidity, salt content, and coexisting ions, leading to decreased adsorption activity, poor selectivity, and even damage and / or decomposition of the material structure.

[0045] This invention utilizes a mixed ammonium / organic amine template to synthesize hydrated Na. + A stepwise ion-activated method was used to prepare a mass-producible Na-SbS ion exchanger, achieving highly selective enrichment of Cs in nitric acid solution (pH = 1-3). + Ions. Na-SbS against Cs + It exhibits rapid adsorption kinetics (1 min, R > 82%) and high equilibrium removal rate (10 min, R > 94%), however, it has limitations for coexisting Sr. 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ Eu 3+ Na + K + Mg 2+ Ca 2+ Many ions showed almost no adsorption effect (120 min, R < 10%), and each ion had little to no adsorption effect with Cs. + Separation coefficient SF between Cs / M All are greater than 141, which can reduce Cs + It is completely separated from other coexisting ions.

[0046] The beneficial effects of this invention are as follows:

[0047] 1. This invention employs a mixed solvent synthesis strategy using methylamine hydrochloride, N,N'-dimethylurea, and hydrazine hydrate (98%), inducing Na+ hydration via a mixed template of ammonium / organic amine / water molecules. + An inorganic layered Na-SbS ion exchanger with elliptical cavities was prepared using a stepwise ion-activated method. The exchanger has a well-defined molecular structure, with elliptical cavities formed by Cs. + It provides precise adsorption sites with good selectivity. This exchanger also features simple preparation, good reproducibility, high yield, and radiation resistance.

[0048] 2. The Na-SbS ion exchanger prepared in this invention exhibits good performance against Cs in acidic solution. +It exhibits extremely high selective enrichment capacity. In solutions containing Sr at pH 1-3... 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ Eu 3+ Na + K + Mg 2+ Ca 2+ When multiple ions coexist, the exchanger's effect on Cs + The removal rate can reach over 94%, but the removal rate for coexisting ions is less than 10%.

[0049] 3. The Na-SbS ion exchanger prepared in this invention has a positive effect on Cs. + It exhibits fast adsorption kinetics, high removal rate, and maximum adsorption capacity. In pure water, Na-SbS exhibits strong adsorption capacity for Cs. + The removal rate reached 99.21% within 1 minute and reached equilibrium within 5 minutes, with a removal rate of 99.68% and a saturated adsorption capacity of 101.26 mg / g. -1 It is suitable for emergency treatment of water bodies containing radioactive ions.

[0050] 4. The Na-SbS ion exchanger prepared by this invention has strong acid and alkali resistance. It can maintain good stability from NaOH solution with pH=12 to nitric acid solution with a concentration of 3.5M, and is suitable for treating acidic and alkaline radioactive waste. Attached image description:

[0051] Figure 1 The diagram shows the preparation process of the Na-SbS ion exchanger in this invention, along with the overall appearance and magnified morphology images of the product. Figure 1 (a) in the diagram is a flowchart of the preparation process of Na-SbS ion exchanger. Figure 1 Image (b) shows the overall appearance and magnified morphology of the Na-SbS ion exchanger product.

[0052] Figure 2 This is an image showing the molecular structure of the Na-SbS ion exchanger determined by single-crystal XRD in this invention. Figure 2 (a) shows the structure of the inorganic layers in the Na-SbS ion exchanger. Figure 2 (b) in the figure represents the stacking form of the Na-SbS ion exchanger.

[0053] Figure 3 This is the energy-dispersive X-ray spectrum of the Na-SbS ion exchanger in this invention.

[0054] Figure 4The SbS precursor, Na-SbS ion exchanger, and Cs in this invention are used in this invention. + Thermogravimetric curves of the saturated exchange product Cs-SbS, under argon atmosphere, at a heating rate of 10 °C / min. -1 .

[0055] Figure 5 The image shows the XRD pattern of a single crystal of the SbS precursor used in this invention, as well as the XRD patterns of the SbS precursor, Na-SbS ion exchanger, and Cs. + Measured XRD pattern of the saturated exchange product Cs-SbS.

[0056] Figure 6 The images show the XRD patterns of the Na-SbS ion exchanger in this invention before and after irradiation with 200 kGy β or 200 kGy γ rays.

[0057] Figure 7 The SbS precursor and Na-SbS ion exchanger used in this invention for Cs in water at pH 6 + Graph showing the change in ion removal rate over time.

[0058] Figure 8 The SbS precursor and Na-SbS ion exchanger used in this invention for Cs in water at pH 2 + Graph showing the change in ion removal rate over time.

[0059] Figure 9 The Na-SbS ion exchanger in this invention reacts with Cs in water at pH 6. + Isothermal adsorption curves of ions and fitting results.

[0060] Figure 10 The Na-SbS ion exchanger in this invention reacts with Cs in water at pH 2. + Isothermal adsorption curves of ions and fitting results.

[0061] Figure 11 The Na-SbS ion exchanger and Cs in this invention + SEM images and elemental distribution diagrams of the saturated exchange product Cs-SbS.

[0062] Figure 12 Cs in this invention + Energy dispersive X-ray spectrum of saturated exchange product Cs-SbS.

[0063] Figure 13 The Na-SbS ion exchanger in this invention is used for Cs + The trend of ion removal rate with the initial pH of the solution and the pH of the solution after exchange.

[0064] Figure 14The Na-SbS ion exchanger in this invention is used for Cs + The trend of ion removal rate with the concentration of nitric acid in the solution.

[0065] Figure 15 This shows the variation of Sb precipitation amount in the Na-SbS ion exchanger with the pH of the solution in this invention.

[0066] Figure 16 The effect of Na-SbS ion exchanger on Cs under different acidity and alkalinity conditions in this invention + XRD pattern of the product after ion adsorption.

[0067] Figure 17 The Na-SbS ion exchanger in this invention is used for Cs + The removal rate of ions varies with the number of single Na+ ions coexisting in the solution. + K + Mg 2+ Ca 2+ Trends in ion concentration.

[0068] Figure 18 The Na-SbS ion exchanger of this invention is used in deionized water (DW), mineral water (MW), tap water (TW), lake water (LW), and seawater (SW) environments to enhance the exchange of Cs. + Ion removal rate.

[0069] Figure 19 The Na-SbS ion exchanger in this invention is used in single CO3... 2- HCO3 - NO3 - and SO4 2- When it exists for Cs + Ion removal rate.

[0070] Figure 20 The Na-SbS ion exchanger in this invention is used for mixed Cs + 、Sr 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ and Eu 3+ The graph shows the change in the removal rate of various ions in the solution over time.

[0071] Figure 21 The Na-SbS ion exchanger in this invention is used for mixed Cs + 、Sr 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ and Eu3+ The trend of removal rate of various ions in solution with the change of initial pH of solution.

[0072] Figure 22 The Na-SbS ion exchanger in this invention is used to treat Cs under pH=6 conditions. + And 10 times the excess of single Sr 2 + Co 2+ Ni 2+ Ce 3+ Comparison of removal rates of coexisting ions.

[0073] Figure 23 The Na-SbS ion exchanger in this invention is used to treat Cs under pH=6 conditions. + And 50 times the excess of single Sr 2 + Co 2+ Ni 2+ Ce 3+ Comparison of removal rates of coexisting ions.

[0074] Figure 24 The Na-SbS ion exchanger in this invention, under pH=2 conditions, enhances the exchange capacity of Cs. + And 10 times the excess of single Sr 2 + Co 2+ Ni 2+ Ce 3+ Comparison of removal rates of coexisting ions.

[0075] Figure 25 The Na-SbS ion exchanger in this invention, under pH=2 conditions, enhances the exchange capacity of Cs. + And 50 times the excess of a single Sr 2 + Co 2+ Ni 2+ Ce 3+ Comparison of removal rates of coexisting ions.

[0076] Figure 26 This is a diagram of the Na-SbS-filled ion exchange column apparatus used in this invention.

[0077] Figure 27 The Na-SbS-filled ion exchange column used in this invention, under pH=2 conditions, is suitable for processing ion exchange columns containing mixed Cs. + 、Sr 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ and Eu 3+The graph shows the trend of ion removal rate as a function of bed volume in the first round of column filtration experiment of ion solution.

[0078] Figure 28 This is a graph showing the trend of ion removal rate as a function of bed volume in the first round of elution experiment of the Na-SbS-filled ion exchange column in this invention.

[0079] Figure 29 The Na-SbS-filled ion exchange column used in this invention, under pH=2 conditions, is suitable for processing ion exchange columns containing mixed Cs. + 、Sr 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ and Eu 3+ The graph shows the trend of ion removal rate as a function of bed volume in the second-round column filtration experiment of ion solution.

[0080] Figure 30 This is a graph showing the trend of ion removal rate as a function of bed volume in the second round of elution experiments using the Na-SbS-filled ion exchange column of this invention.

[0081] Figure 31 The Na-SbS-filled ion exchange column used in this invention, under pH=2 conditions, is suitable for processing ion exchange columns containing mixed Cs. + 、Sr 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ and Eu 3+ The graph shows the trend of ion removal rate as a function of bed volume in the experiment of third-round column filtration of ion solution.

[0082] Figure 32 This is a graph showing the trend of ion removal rate as a function of bed volume in the third round of elution experiment of the Na-SbS packed ion exchange column in this invention.

[0083] Figure 33 The images show photographs of the Na-SbS / PTFE microporous filter membrane in flat and bent states, as well as a diagram of an apparatus for applying the Na-SbS / PTFE microporous filter membrane to vacuum filtration.

[0084] Figure 34 The image shown is a SEM image of the cross-section of the Na-SbS / PTFE microporous filter membrane in this invention, with embedded small images showing SEM images of the filter membrane surface.

[0085] Figure 35 The Na-SbS / PTFE microporous filter membrane in this invention is used to filter mixed Cs at pH=6. +、Sr 2+ Co 2 + Ni 2+ Ce 3+ 、Sm 3+ and Eu 3+ The graph shows the trend of ion removal rate as a function of the volume of the filtered solution in the first round of membrane filtration experiments.

[0086] Figure 36 This is a graph showing the trend of ion removal rate as a function of the volume of the filtration solution in the first round of elution experiment using the Na-SbS / PTFE microporous filter membrane in this invention.

[0087] Figure 37 The Na-SbS / PTFE microporous filter membrane in this invention is used to filter mixed Cs at pH=6. + 、Sr 2+ Co 2 + Ni 2+ Ce 3+ 、Sm 3+ and Eu 3+ The graph shows the trend of ion removal rate as a function of the volume of the filtered solution during the second round of membrane filtration experiments on the ion solution.

[0088] Figure 38 This is a graph showing the trend of ion removal rate as a function of the volume of the filtration solution in the second round of elution experiment using the Na-SbS / PTFE microporous filter membrane in this invention.

[0089] Figure 39 The Na-SbS / PTFE microporous filter membrane in this invention is used to filter mixed Cs at pH=6. + 、Sr 2+ Co 2 + Ni 2+ Ce 3+ 、Sm 3+ and Eu 3+ The graph shows the trend of ion removal rate as a function of the volume of the filtered solution during the third round of membrane filtration experiments.

[0090] Figure 40 This is a graph showing the trend of ion removal rate as a function of the volume of the filtration solution in the third round of elution experiment using the Na-SbS / PTFE microporous filter membrane in this invention. Detailed implementation method:

[0091] The present invention will now be described in detail with reference to embodiments and accompanying drawings, in order to help readers better understand the technical solutions, but the scope of protection of the present invention is not limited thereto.

[0092] Unless otherwise specified, all raw materials used in the examples were purchased commercially and were not further purified or processed.

[0093] The testing method in the embodiments of the present invention is as follows:

[0094] Diffraction data of powder samples were measured using a Rigaku SmartLab 9kW X-ray diffractometer (XRD), Cu target, Kα rays.

[0095] Crystal structure data were acquired using a Rigaku XtaLab PRO single-crystal X-ray diffractometer (SC-XRD), Cu target, Kα rays.

[0096] Energy-dispersive X-ray spectroscopy (EDS) and elemental distribution were measured using a FEIQuanta FEG 250 scanning electron microscope.

[0097] The concentration of ions in the solution was determined using a ThermoFisher iCAP RQ inductively coupled plasma mass spectrometer (ICP-MS).

[0098] In the embodiments of the present invention, the removal rate R (%) is calculated in the following manner;

[0099] R = (C0 - C) f ) / C0×100% (1)

[0100] In the embodiments of the present invention, the allocation coefficient K d (mL g -1 ) is calculated in the following way;

[0101] K d =V / m×(C0-C f ) / C f (2)

[0102] In the embodiments of the present invention, the Langmuir isothermal adsorption model is represented as follows:

[0103] q e =q m (bC e ) / (1+(bC e (3)

[0104] Example 1

[0105] Preparation and product characteristics of Na-SbS ion exchanger.

[0106] like Figure 1As shown in (a), 0.54 g (8 mmol) of methylamine hydrochloride, 1.41 g (16 mmol) of N,N'-dimethylurea, and 0.4 mL (8.24 mmol) of hydrazine hydrate (98%) were mixed. Then, 0.122 g (1 mmol) of antimony powder and 0.128 g (4 mmol) of sulfur powder were added and mixed until a viscous consistency was reached. The mixture was then sealed in a 20 mL stainless steel reactor lined with polytetrafluoroethylene and reacted at 170 °C for 4 days. After cooling to room temperature, the mixture was washed 3-4 times with deionized water and then air-dried to obtain 0.111 g of crystalline SbS precursor. 0.1 g of the SbS precursor was added to 20 mL of 2 M sodium chloride solution and stirred at 80 °C for 8 hours. The solid product was filtered, washed twice with water, washed twice with ethanol, and then air-dried to obtain the product shown in Figure 1. Figure 1 The Na-SbS ion exchanger shown in (b) has a yield of approximately 60.1% based on the antimony powder as the raw material.

[0107] The yield is calculated as follows: (mass of the Na-SbS ion exchanger product / molecular weight of the product × 9) / (moles of antimony powder in the raw material) × 100%.

[0108] Figure 2 The image shows the single-crystal XRD molecular structure of Na-SbS ion exchanger. From... Figure 2 As shown in (a), each Sb atom coordinates with three adjacent S atoms to form a {SbS3} trigonal pyramid. The three {SbS3} units are connected by a shared vertex S atom, forming a {Sb3S6} cluster. The {Sb3S6} cluster is alternately connected with Sb atoms to form a {Sb4S6} chain, and two adjacent chains are connected by {SbS3} bridging groups to form a ribbon-like {Sb9S} chain. 15}, and form a 10-membered ring {Sb 10 S 10 The elliptical cavity of} contains hydrated Na + Ions and CH3NH3 + ions (Na) + CH3NH3 + A molar ratio of 2:1) is used as a countercation to fill the central positions on both sides of the elliptical cavity, forming Cs. + It provides highly selective adsorption sites. The bands are aligned in parallel and connected by weak Sb···S interactions to form a two-dimensional [Sb9S] band. 15 ] n 3n- Anion exchange membranes. For example... Figure 2 As shown in (b), the anion plates are arranged in parallel to form the Na-SbS lattice structure.

[0109] Table 1 lists the mass percentages of each element in the Na-SbS ion exchanger obtained based on ICP-MS and C, H, N, O, and S elemental analysis techniques. The measured results are in good agreement with the theoretical values.

[0110] Table 1. Measured values ​​of element content (mass percentage) in Na-SbS ion exchanger and its comparison with that based on (CH3NH3)Na2Sb9S 15 The theoretical value calculated from the molecular formula of 3.5H2O.

[0111] Element types N(％) C(％) H(％) O(％) S(％) Na (%) Sb(%) Experimental values 0.87 0.64 0.852 3.39 27.455 2.84 64.51 Theoretical value 0.82 0.70 0.76 3.26 28.00 2.68 63.79

[0112] like Figure 3 As shown, the energy-dispersive X-ray spectroscopy confirms that the mass and atomic percentage of each element in the Na-SbS ion exchanger conform to (CH3NH3)Na2Sb9S 15 The elemental composition of the molecular formula 3.5H2O.

[0113] like Figure 4 As shown, the Na-SbS ion exchanger loses 3.67% of its weight in the temperature range of 40-200℃, which is consistent with the theoretical weight loss of 3.67% for water of crystallization molecules within the material, confirming the (CH3NH3)Na2Sb9S 15 The molecular formula 3.5H₂O does indeed contain 3.5 molecules of water of crystallization, i.e., Na. + It exists in the form of hydrated ions.

[0114] like Figure 5 As shown, the XRD pattern of the SbS precursor is consistent with the spectrum fitted from the single crystal data, proving that the prepared SbS precursor has high purity. Na-SbS ion exchanger and its Cs + The diffraction pattern of the adsorption-saturated product Cs-SbS is similar to that of the SbS precursor, proving that after Na... + Activation and Cs + After adsorption, the anionic framework of the material is still maintained.

[0115] like Figure 6 As shown, the powder XRD patterns of Na-SbS ion exchanger before and after irradiation with 200 kGyβ or 200 kGyγ are highly consistent, indicating that the internal framework structure of the material is well maintained, the material does not decompose, and it has excellent radiation resistance.

[0116] Example 2

[0117] SbS precursor and Na-SbS ion exchanger for Cs under neutral and acidic conditions + Adsorption kinetics of ions.

[0118] Take SbS precursor, Na-SbS ion exchanger and Cs containing 6 ppm respectively + Aqueous solutions mixed (V / m = 1000 mL g) -1 The mixture was stirred continuously at room temperature (20℃) for different times (0-240 min) with pH = 2 and 6. The resulting solutions were filtered, diluted, and then Cs was determined by ICP-MS. + The concentration of ions. For example... Figure 7 As shown, under neutral pH = 6 conditions, the SbS precursor for Cs + The adsorption rate of ions is slow; only 39.16% of Cs can be adsorbed in 1 minute. + It takes 20 minutes to reach equilibrium, at which point Cs... + The removal rate was 89.19%. The activated Na-SbS ion exchanger showed a significantly increased adsorption rate, removing 99.21% of Cs within 1 minute. + The ions reach adsorption equilibrium in 5 minutes, at which point Cs + The removal rate was 99.68%, and the corresponding allocation coefficient K d Cs 3.11×10 5 mL g -1 .like Figure 8 As shown, under acidic conditions of pH 2, the SbS precursor and Na-SbS ion exchanger have different effects on Cs. + The adsorption rate and removal rate of ions can be maintained well, with the Na-SbS ion exchanger showing good performance in adsorption equilibrium for Cs. + The removal rate was 97.14%. This indicates that the Na+ removal from the precursor is effective. + Ion activation can effectively enhance the Cs-linked properties of ion exchangers. + It exhibits high adsorption rate and removal rate, and its performance is unaffected by changes in solution acidity, demonstrating good adsorption capacity even under acidic conditions.

[0119] Example 3

[0120] Na-SbS ion exchanger for Cs under neutral and acidic conditions + Isothermal adsorption curves of ions.

[0121] Take samples Na-SbS and Cs + Aqueous solutions mixed (V / m = 1000 mL g) -1 At pH=6, Cs + When the initial ion concentration is 3-530 ppm and the pH is 2, Cs +The initial ion concentration was 3-695 ppm, and the mixture was stirred continuously at room temperature (20℃) for 4 hours. The initial and post-reaction solutions were collected, filtered, diluted, and then Cs were determined by ICP-MS. + The concentration of ions. For example... Figure 9 , Figure 10 As shown, by fitting the isothermal adsorption curves using the Langmuir model, it can be determined that Na-SbS adsorbs Cs under neutral pH=6 and acidic pH=2 conditions. + The saturated adsorption capacity of the ions was 101.26 mg g. -1 and 63.02 mg g -1 This indicates that Na-SbS ion exchangers exhibit good adhesion to Cs under neutral and acidic conditions. + All ions exhibit high saturation adsorption capacity.

[0122] Example 4 Na-SbS ion exchanger and Cs + Characterization of the adsorption saturated product Cs-SbS.

[0123] Take a sample of Na-SbS and 8000 ppm of Cs + Mixing aqueous solutions of ions (V / m = 1000 mL g) -1 The mixture was stirred continuously at room temperature (pH=6) for 4 hours. After the reaction, the solid product was filtered out, washed three times with water, and then naturally dried to obtain the saturated adsorbed product Cs-SbS. Figure 11 As shown, Na-SbS ion exchanger and Cs + After ion exchange, the crystal morphology of the product Cs-SbS remained intact, with no surface pulverization or breakage, confirming that the Na-SbS ion exchanger possesses high mechanical strength to withstand ion substitution and shuttle. Elemental distribution shows that Na and Cs are uniformly distributed in both the Na-SbS and Cs-SbS samples.

[0124] Figure 12 This is the energy-dispersive X-ray spectrum of Cs-SbS, where the atomic percentages of each element are consistent with the elemental composition after material exchange in Example 1 and the Cs composition fitted in Example 3. + Saturated adsorption capacity.

[0125] Example 5: Na-SbS ion exchanger on Cs under different acid and alkaline environments + Ion adsorption performance test.

[0126] Take samples of Na-SbS and 6 ppm Cs at different pH levels. + The solutions were mixed (pH = 1-12 and 1-4.5M nitric acid solution, V / m = 1000 mL g). -1The mixture was stirred continuously at room temperature (20℃) for 2 hours. The initial and post-reaction solutions were then filtered, diluted, and Cs were determined by ICP-MS. + The concentration of ions. For example... Figure 13 As shown, Na-SbS affects Cs in the pH range of 1-12. + All ions exhibit good adsorption activity, with partition coefficients R0 at pH 2-12. Cs It can reach 98.16%-99.73%; at pH=1, R Cs It can also reach 91.90%.

[0127] like Figure 14 As shown, Na-SbS reacts with Cs in a 1M nitric acid solution. + The removal rate can reach 55.97%; when the nitric acid concentration increases to 2M, 3M, and 3.5M, Cs + The removal rates of Na-SbS for Cs were 33.42%, 22.32%, and 15.14%, respectively. + The removal rate of Cs decreases further with increasing nitric acid concentration; when the concentration increases to 4.5M, the removal rate further decreases. + The removal rate decreased to 3.92%. This fully demonstrates that the Na-SbS ion exchanger still retains a certain amount of Cs even under strongly acidic conditions. + Ion adsorption activity.

[0128] In addition, the solutions after adsorption reactions under different acid and alkaline conditions were filtered, diluted, and then the concentration of Sb was determined by ICP-MS to assess the chemical stability of the Na-SbS exchanger. Figure 15 As shown, the Sb concentration of the Na-SbS ion exchanger was 12.42, 15.37, and 7.32 ppm at pH = 12, pH = 9, and pH = 6, respectively. With increasing solution acidity, the amount of Sb precipitated gradually decreased, ranging from 0.79 to 3.21 ppm in the range of pH = 3 to 3.5M nitric acid solution, accounting for only 0.12-0.50% of the Sb composition in the added Na-SbS ion exchanger. However, when the nitric acid concentration increased to above 4M, the amount of Sb precipitated gradually increased, and Na-SbS gradually dissolved. This indicates that the Na-SbS ion exchanger has excellent acid resistance and can withstand the corrosion of 3.5M concentrated nitric acid.

[0129] Cs + After ion exchange, the solid products in different acid and alkaline environments were filtered, washed three times with water, and then naturally dried before XRD analysis. Figure 16As shown, the Na-SbS ion exchanger maintains similar diffraction patterns across a pH range of 2-12. However, when the solution acidity is further increased to pH 1 up to 3.5M nitric acid solution, the peak intensity of the XRD pattern decreases, indicating that the Na-SbS ion exchanger transforms into a solid acid form. This demonstrates that the Na-SbS ion exchanger exhibits good structural stability in different acidic and alkaline environments.

[0130] Example 5

[0131] Na-SbS ion exchanger for Cs in aqueous environments containing other coexisting ions + Ion adsorption performance test.

[0132] Na-SbS ion exchanger was added to a solution containing 6 ppm of Cs. + Ions and single Na + K + Mg 2+ Ca 2+ (All were prepared with chloride, and the concentration of each cation was 0.1-100 mmol / L) -1 In a mixed solution (V / m = 1000 mL g) -1 The mixture was stirred continuously at room temperature (20℃) for 2 hours. The initial and post-reaction solutions were then filtered, diluted, and Cs were determined by ICP-MS. + The concentration. For example... Figure 17 As shown, the concentration range is 0.1-100 mmol / L. -1 Na + Mg 2+ Ca 2+ Ion pairs Cs + The adsorption of Cs is almost unaffected. + The removal rates can all reach over 95.68%. Low concentrations of K + For Cs + The adsorption of ions has little effect; as the concentration increases, K... + For Cs + The adsorption of ions produced a certain inhibitory effect, but even K + The concentration increased to 10, 100 mmol / L -1 Cs + The removal rates still reached 88.59% and 40.22%, respectively. This shows that the Na-SbS ion exchanger effectively removes Cs... + The adsorption of ions exhibits high selectivity and can effectively resist coexisting Na+. + K + Mg 2+ Ca 2+ The influence of ions.

[0133] Na-SbS ion exchanger was added to a solution containing 6 ppm of Cs. + In deionized water (DW), mineral water (MW), tap water (TW), lake water (LW), and seawater (SW) solutions (V / m = 1000 mL g), the concentration of ions was measured. -1 The mixture was stirred continuously at room temperature (20℃) for 2 hours. The initial and post-reaction solutions were then filtered, diluted, and Cs were determined by ICP-MS. + The concentration. For example... Figure 18 As shown, Na-SbS pairs with Cs + The adsorption of ions is almost unaffected by DW, MW, TW, and LW environments, Cs + The removal rates were all above 95.4%. Even in seawater (SW), Cs + The removal rate can reach 77.63%. This indicates that Na-SbS ion exchanger is suitable for various actual water environments with different salinities.

[0134] Na-SbS ion exchanger was added to a solution containing 3 ppm Cs. + Ions and single CO3 2- HCO3 - NO3 - SO4 2- In a mixed solution (all prepared from sodium salts, each anion concentration of 30 ppm) (V / m = 1000 mL g -1 The mixture was stirred continuously at room temperature (20℃) for 2 hours. The initial and post-reaction solutions were then filtered, diluted, and Cs were determined by ICP-MS. + The concentration. For example... Figure 19 As shown, 30 ppm CO3 2- HCO3 - NO3 - SO4 2- Coexisting ion pairs Cs + Almost no impact, Cs + The ion removal rates were all above 99.53%. This indicates that the Na-SbS ion exchanger effectively removes Cs... + The adsorption exhibits high selectivity and can effectively resist coexisting CO3. 2- HCO3 - NO3 - SO4 2- The influence of ions.

[0135] The Na-SbS sample was added to a mixture containing Cs. + 、Sr 2+ Co 2+ Ni 2+ Ce3+ 、Sm 3+ Eu 3+ Cations (prepared from chloride, each cation concentration 6 ppm) in solutions of different acidities (V / m = 1000 mL g) -1 The mixture was stirred continuously for different times (0-120 min) at room temperature (20℃) with pH = 2-10. The resulting solution was then filtered, diluted, and Cs was determined by ICP-MS. + 、Sr 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ Eu 3+ The concentration. For example... Figure 20 As shown, under pH=6 conditions, the Na-SbS ion exchanger reduced the concentration of Cs within 1 minute. + The removal rate can reach 97.74%, while the removal rate for other coexisting ions is no more than 13.51%; it can reach Cs within 20 minutes. + Adsorption equilibrium was reached, with a removal rate of 99.79%, while other competing ions failed to reach equilibrium within 120 minutes, with a maximum removal rate not exceeding 68.92%. Figure 21 As shown, within a pH range of 2-10, after 120 min of exchange, the Na-SbS ion exchanger can selectively capture Cs. + Especially in solutions with pH = 2 or 3, Na-SbS ion exchangers can remove more than 95% of Cs. + It only adsorbs certain ions, showing no adsorption activity for any other coexisting ions, with a removal rate of approximately 0-5%. This fully demonstrates that when nuclear wastewater or nuclear-contaminated water contains various other fission products (such as Sr), it is highly susceptible to damage. 2+ ), activated products (Co) 2+ Ni 2+ ), rare earth elements (Ce) 3+ 、Sm 3+ Eu 3+ At that time, the Na-SbS ion exchanger still exhibited extremely high Cs. + Adsorption selectivity allows for efficient adsorption of Cs. + Separate from other nuclides.

[0136] The Na-SbS sample was added to a solution containing 6 ppm Cs. + Ions and single Sr 2+ Co 2+ Ni 2+ Ce 3+ In a mixed solution of ions (concentrations of 60 ppm and 300 ppm) (V / m = 1000 mL g) -1(pH = 2, 6), stirred continuously for 2 hours at room temperature (20℃). Initial and post-reaction solutions were collected, filtered, diluted, and Cs determined by ICP-MS. + 、Sr 2+ Co 2+ Ni 2+ Ce 3+ The concentration. For example... Figure 22 and Figure 23 As shown, in a single Sr 2+ Co 2+ Ni 2+ Ce 3+ Ion concentrations 10 to 50 times higher than Cs + In a solution with pH = 6, Na-SbS affects Cs + The removal rates of all ions were above 99.35%, while the removal rates of other coexisting ions did not exceed 17.88%; for example... Figure 24 and Figure 25 As shown, when the acidity of the solution increases to pH=2, Cs + The removal rate of Cs ions remained above 96.23%, while the removal rate of other coexisting ions did not exceed 10.63%. This indicates that, regardless of neutral or acidic conditions, the Na-SbS ion exchanger is effective for removing Cs ions. + It exhibits extremely high selectivity, even against 10 to 50 times the excess of Sr. 2+ Co 2+ Ni 2 + Ce 3+ Ions have no adsorption activity.

[0137] Example 6

[0138] Ion exchange columns are used for Cs in acidic solutions containing multiple coexisting ions. + Ion adsorption and elution.

[0139] like Figure 26 As shown, a 1 mL plastic chromatography column was filled with Na-SbS sample (approximately 0.67 g). A constant flow pump was used to transfer a 9100 fixed bed volume (1 fixed bed volume = 1 mL) containing mixed Cs... + 、Sr 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ Eu 3+ An aqueous solution (pH = 2, concentration of each ion 6 ppm) was introduced into the exchange column and allowed to proceed at a rate of 3 mL / min. -1The exchange resin was flowed at a rate that allowed it to pass through. Samples were taken from the effluent every 100 fixed bed volumes, diluted, and then analyzed for Cs using ICP-MS. + 、Sr 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ Eu 3+ The concentration of ions was determined to complete the first round of adsorption experiments. Then, a constant flow pump was used to introduce 1000 mL of 2M NaCl solution into the exchange column, at a rate of 3 mL / min. -1 The exchange resin was flowed at a rate of [missing information], and samples were taken from the effluent every 100 fixed bed volumes. After dilution, the Cs content was determined by ICP-MS. + 、Sr 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ Eu 3+ The concentration of ions was determined to complete the first round of elution experiments.

[0140] The second and third adsorption-elution cycles were then performed. Unlike the first adsorption experiment, the mixed ion solution in the latter two adsorption experiments was processed in a volume of 500 fixed bed volume. Samples were taken from the effluent every 50 fixed bed volumes, diluted, and the ion concentration was measured by ICP-MS.

[0141] like Figure 27 As shown, in the first round of adsorption experiments, the Na-SbS-filled exchange column was effective against Cs. + The removal rate of Cs is much higher than that of other coexisting ions. When the effluent volume is between 0 and 2500 bed volumes, Cs... + The removal rate remained above 99.21%, and when the effluent volume increased to 2600-9100 bed volume, Cs + The removal rate of [specific substance] gradually decreased, eventually dropping to 2.34%; in contrast, other [specific substances] showed better removal rates throughout the experiment. 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ Eu 3+ The removal rates of coexisting ions fluctuated between ±8%. This indicates that the Na-SbS packed exchange column is effective for Cs... + It exhibits high adsorption selectivity and can separate Cs from solutions containing multiple radionuclides. + ion.

[0142] like Figure 28As shown, in the first round of elution experiments, when the outflow volume of 2M NaCl eluent increased from 0 to 1000 bed volumes, Cs + The removal rate gradually increased from -760.95% to -105.91% (Note: a negative ion removal rate here indicates an increase in the concentration of that ion in the solution; -100% here means that the concentration of that ion in the eluent is the same as the initial concentration in the adsorption experiment), while other coexisting ions (Sr... 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ Eu 3+ The removal rates of Cs were close to 0%. This not only confirms that after the first round of adsorption, only Cs were adsorbed in the Na-SbS exchanger. + The absence of other ions further indicates that the 2M NaCl solution is effective against Cs. + Ions have a good elution effect, which is beneficial for the regeneration of exchangers and the recovery of radionuclides.

[0143] like Figures 29 to 32 As shown, in the second and third rounds of adsorption-elution cycle experiments, the Na-SbS-filled exchange column was effective against Cs. + Ions maintain good selective removal effect.

[0144] Example 7

[0145] Microporous membranes are effective for Cs in solutions containing multiple coexisting ions. + Ion adsorption and elution.

[0146] Na-SbS ion exchanger was ball-milled into micron-sized crystal particles. The ball-milled Na-SbS was then dissolved with polyvinylidene fluoride (PVDF) in N-methylpyrrolidone (NMP) at a concentration of 40 mg / mL. -1 Mix the components thoroughly at a mass ratio of 9:1, and then evenly spread the mixture onto a 5cm diameter circular PTFE substrate membrane using a spatula. Allow it to air dry at room temperature to obtain a Na-SbS / PTFE microporous filter membrane. Figure 33 As shown, the obtained Na-SbS / PTFE microporous filter membrane is brick red and can withstand no less than 100 bending cycles without significant damage. Figure 34 As shown, the thicknesses of the Na-SbS layer and the PTFE layer are approximately 70 and 140 μm, respectively. After ball milling, the particle size of Na-SbS is only 1-5 μm, which greatly increases the surface area of ​​the ion exchanger and is beneficial to improving the adsorption rate of Na-SbS. In use, the Na-SbS / PTFE microporous membrane is laid flat on a sand core funnel, and under reduced pressure filtration, 4600 mL of a mixture containing Cs is filtered... + 、Sr 2+Co 2+ Ni 2+ Ce 3+ 、Sm 3+ Eu 3+ The solution (pH = 6, concentration of each ion 2 ppm) was prepared at 36 mL / min. -1 A constant flow rate through the membrane (per 1 cm) 2 The flow rate of the Na-SbS / PTFE microporous membrane was approximately 1.8 mL / min. -1 Samples were taken from the effluent every 100 mL, diluted, and Cs were accurately measured by ICP-MS. + 、Sr 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ Eu 3+ The concentration was determined to complete the adsorption experiment. Then, 2000 mL of 2M NaCl solution was filtered under reduced pressure at 36 mL / min. -1 A constant flow rate through the membrane (per 1 cm) 2 The flow rate of the Na-SbS / PTFE microporous membrane was approximately 1.8 mL / min. -1 Samples were taken from the effluent every 100 mL, diluted, and Cs were accurately measured by ICP-MS. + 、Sr 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ Eu 3+ The concentration was determined to complete the elution experiment.

[0147] Subsequent adsorption-elution cycles were performed. Unlike the first adsorption cycle, the volume of the mixed ion solution treated in the latter two cycles was 500 mL. Samples were taken from the effluent every 50 mL, diluted, and the ion concentration was measured using ICP-MS. Similarly, unlike the first elution cycle, the volume of the eluent used in the latter two cycles was 1200 mL. Samples were taken from the effluent every 100 mL, diluted, and the ion concentration was measured using ICP-MS.

[0148] like Figure 35 As shown, in the first round of adsorption experiments, the Na-SbS / PTFE microporous membrane showed good adsorption performance for Cs. + The removal efficiency of Cs ions is higher than that of other competing ions. When the effluent volume is in the range of 0-400 mL, Cs ions are more effective at removing ions. + The ion removal rate was above 99.29%; when the effluent volume was 800 mL, Cs +The ion removal rate remained above 91.64%; when the effluent volume further increased, Cs + The removal rate gradually decreased and dropped to 11.51% when the effluent volume was 4600 mL. For other coexisting ions, the removal rate rapidly decreased to near 0% in the initial stage of filtration and remained there until the end of the experiment.

[0149] like Figure 36 As shown, in the first round of elution experiments, the effluent volume ranged from 0 to 2000 mL, and the initial stage Cs + The highest ion removal rate was -792.67%, then it rapidly increased and remained at around -6%, indicating that 2M NaCl solution can rapidly and thoroughly elute Cs. + Ions. Since no other coexisting ions were adsorbed in the membrane after the adsorption experiment, the removal rate of these coexisting ions was always 0% in the elution experiment.

[0150] like Figures 37 to 40 As shown, in the second and third adsorption-elution cycles, the Na-SbS / PTFE microporous membrane still maintains excellent selective separation of Cs. + The membrane exhibits excellent ion removal performance, maintaining a removal rate of over 99.9% and demonstrating good elution effect, enabling the membrane to be reused.

[0151] Example 8

[0152] The other preparation steps are the same as in Example 1, except that the reaction temperature is changed from 170℃ to 190℃ and the reaction time is changed from 4 days to 2 days. The obtained material, under acidic pH=2 conditions, reacts with 6 ppm Cs in solution. + The equilibrium removal rate can reach 96.82% (V / m = 1000 mL g). -1 The material properties are similar to those obtained in Example 1.

[0153] Example 9

[0154] The other preparation steps are the same as in Example 1, except that the amount of methylamine hydrochloride added is replaced by 0.27 g (4 mmol) instead of 0.54 g (8 mmol), and the amount of N,N'-dimethylurea added is replaced by 1.06 g (12 mmol) instead of 1.41 g (16 mmol). The resulting material, under acidic conditions of pH 4, reacts with 6 ppm Cs in the solution. + The equilibrium removal rate can reach 97.66% (V / m = 1000 mL g). -1 The material properties are similar to those obtained in Example 1.

[0155] Example 10

[0156] The other preparation steps are the same as in Example 1, except that the concentration of the sodium chloride solution used to activate the SbS precursor is replaced with 0.5M instead of 2M. The resulting material, under neutral pH=6 and acidic pH=2 conditions, reacts with Cs in the solution. + The saturated adsorption capacity of the ions was 105.53 mg g. -1 and 60.14mg g -1 (V / m=1000mL g -1 The saturated adsorption capacity is close to that of the material obtained in Example 1.

[0157] From the above examples, we can see that hydrated Na can be synthesized through a simple mixed ammonium / organic amine template. + A stepwise method of ion activation can prepare Na-SbS ion exchangers with specific compositions and structures, which can selectively separate and enrich Cs from acidic solutions containing multiple coexisting ions. + Na-SbS ions also have advantages such as high yield, radiation resistance, and fast kinetic response.

[0158] The above-described embodiments are not intended to limit the present invention in any way. Any modifications or alterations made by those skilled in the art without departing from the scope of the present invention using the above-described technical content are equivalent to equivalent implementations and fall within the scope of the technical solution.

[0159] Matters not covered in this invention are common knowledge.

Claims

1. A highly selective Cs + Ion exchangers, characterized by The molecular formula of this ion exchanger is: (CH3NH3)Na2Sb9S 15 ·3.5H2O, denoted as Na-SbS; In the aforementioned exchanger, each Sb atom is coordinated by three S atoms to form a {SbS3} trigonal pyramidal unit. Three {SbS3} units are connected at common angles to form a {Sb3S6} cluster. The {Sb3S6} cluster is alternately connected to Sb atoms to form a {Sb4S6} chain. Two adjacent chains are connected by {SbS3} bridging groups to form a ribbon-like {Sb9S} chain. 15 }, and form a 10-membered ring {Sb 10 S 10 The elliptical cavity of} contains hydrated Na + The ions, acting as counter cations, fill the central positions on both sides of the elliptical cavity, forming Cs. + Provides highly selective adsorption sites; The bands are arranged in parallel and connected by Sb···S weak interactions to form a two-dimensional [Sb9S] band. 15 ] n 3n- Anion plates together construct the Na-SbS crystal lattice structure.

2. The highly selective Cs as described in claim 1 + Preparation methods of ion exchangers Its characteristic is that the method includes the following steps: (1) Add methylamine hydrochloride, N,N'-dimethylurea and hydrazine hydrate to the reaction vessel and stir to form a mixed solvent. Then add antimony powder and sulfur powder and stir evenly. React at 150-200 °C for 2-5 days, cool naturally, wash with water 1-3 times, and dry to obtain the crystalline precursor (NH4). 0.5 (CH3NH3) 2.5 Sb9S 15 0.5H₂O, denoted as SbS; The molar ratios are: methylamine hydrochloride: N,N'-dimethylurea = 1:1-3; hydrazine hydrate: N,N'-dimethylurea = 1:1-3; antimony powder: sulfur powder: methylamine hydrochloride = 1:1-5:4-10. (2) Soak the crystal precursor in 0.3-3 M NaCl aqueous solution, stir at 70-90 °C for 2-24 h, filter, wash with water 3-5 times, and air dry to obtain Na-SbS ion exchanger.

3. The highly selective Cs as described in claim 2 + A method for preparing an ion exchanger, characterized in that the hydrated hydrazine has a mass percentage concentration of 98%.

4. The highly selective Cs as described in claim 1 + The application of ion exchangers is characterized by their use in enriching Cs from acidic solutions containing multiple coexisting metal ions. + ion.

5. The highly selective Cs as described in claim 1 + Application of ion exchangers Its characteristics are specifically one of the following three methods: Method 1, Batch adsorption, Includes the following steps: The ion exchanger was added to the solution to be treated and stirred for 0.5 min–12 h to complete the Cs reaction. + Adsorption of ions; The solution to be treated contains Cs + Cs ions + The concentration range of the ions is 0.2-8000 ppm; In the adsorption method described above, the ratio of solution volume to exchanger mass is 100-2000 mL g. -1 ; The pH of the solution to be treated is 0-12; Alternatively, method two, ion exchange column adsorption, includes the following steps: The aforementioned ion exchanger is added as a stationary phase to the chromatography column, and the solution to be treated flows through the column to complete the removal of Cs. + Adsorption of ions; The volume of the packed exchanger stationary phase is 0.5-50 cm³. 3 ; per 1 cm 3 The flow rate of the stationary phase treatment solution is 0.1-20 mL / min. -1 ; The solution to be treated contains Cs + Cs ions + The concentration range of the ions is 0.2-8000 ppm; The pH of the solution to be treated is 0-12; Alternatively, method three, microporous membrane adsorption, includes the following steps: The above-mentioned ion exchanger was ball-milled and then mixed with an N-methylpyrrolidone solution of polyvinylidene fluoride. The mixture was stirred for 5-60 min to obtain a homogeneous slurry. This slurry was then uniformly coated onto the surface of an aqueous PTFE microporous filter membrane substrate with a thickness of 30-200 μm and allowed to air dry naturally for 3-50 h to prepare a Na-SbS / PTFE microporous filter membrane. The solution to be treated was then rapidly passed through the prepared microporous filter membrane using vacuum filtration to complete the treatment of Cs. + Adsorption of ions; The particle size of the ion exchanger after ball milling is 0.5-20 μm; The mass ratio of ion exchanger to polyvinylidene fluoride is 5-50:1; The concentration of N-methylpyrrolidone solution of polyvinylidene fluoride is 10-100 mg / mL. -1 ; In the Na-SbS / PTFE microporous filter membrane, the thickness of the Na-SbS exchanger layer is 20-200 μm; per 1 cm 2 The flow rate of the solution treated by the Na-SbS / PTFE microporous membrane was 0.2-3 mL / min. -1 ; The solution to be treated contains Cs + Cs ions + The concentration range of the ions is 0.2-8000 ppm; The pH of the solution to be treated is 0-12.

6. The highly selective Cs as described in claim 5 + The application of ion exchangers is characterized in that, in methods one, two, and three, the solution to be treated also contains coexisting ions Sr. 2+ Co 2+ Ni 2+ Ce 3+ 、Sm 3+ Eu 3+ Na + K + Mg 2+ Ca 2+ One or more of the following; the concentration range of each ion is 0-20000 ppm; when the content of the element is 0, it means that the element is not present.

7. The highly selective Cs as described in claim 5 + The application of ion exchangers is characterized in that the solution to be treated is radioactive wastewater, or a mixture of one or more of deionized water, lake water, tap water, and seawater, containing Cs. + Ionic solutions.

8. The highly selective Cs as described in claim 5 + The application of ion exchangers is characterized by: The exchanger adsorbs Cs via method one. + Then, immerse the sample in a 1-3 M NaCl solution and stir for 5-24 hours to complete the elution. After elution, remove the sample, wash and dry it, and reuse it. The exchanger adsorbs Cs using method two. + After ionization, elution is completed by continuously pumping 1-3 M NaCl solution through the exchange column, and the solution can be reused. The exchanger adsorbs Cs via method three. + After ionization, a 1-3 M NaCl solution is continuously filtered under reduced pressure through a Na-SbS / PTFE microporous membrane to complete elution, allowing for reuse.

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