KR102355889B1 - Sr(Ⅱ) ion absorbent using a layered vanadosilicate and method of removing Sr(Ⅱ) ion using the same - Google Patents

Abstract

Nuclear power plants contain very harmful radioactive species, including ⁹⁰ Sr, which are highly toxic biologically, causing blood and bone cancers in the human body, as well as useful species such as unused fuel and other useful isotopes. Waste nuclear fuel rods containing these were produced. The spent fuel rods must ultimately be reprocessed to extract useful species from them and remove harmful radioactive species. One of the difficult tasks during the reprocessing process is the removal ^{of traces of 90} Sr (~ 8x10 ^-11 M) from liquid waste (5 M) with ^{high concentrations of Na + .} Since the concentration limit ^{of 90} Sr in drinking water set by the US Environmental Protection Agency ^{is 6.3Х10 -16 M, a 90} Sr adsorbent having a very high selectivity of more than 63 billion times for ⁹⁰ Sr compared to more than 63 billion Na was used. It should be possible to remove the trace amount of ⁹⁰ Sr (~ 8x10 ^{-11 M) by development.} However, to date, no materials have shown the ability to remove the trace ^{90 Sr from the highly concentrated Na + solution.} The present application proposes a novel material capable of capturing ⁹⁰ Sr under the highly concentrated Na ^{+ condition.} The material also has a very high capacity for removing ⁹⁰ Sr from the groundwater and the soil contaminated with ⁹⁰ Sr.

Description

Sr(II) ion absorbent using a layered vanadosilicate and method of removing Sr(II) ion using the same}

Herein, Sr ²⁺ ion adsorbent, the Sr ²⁺ ion method of removing Sr ²⁺ ions by using an adsorbent, tea bags for drinking water purification including the Sr ²⁺ ion adsorbent, and polluted water treatment using the layered silicate Bar I it's about how

The contribution of nuclear power plants to global electricity is significant today (11%) and will continue to increase in the future. However, nuclear power plants produce spent nuclear fuel rods that contain useful and harmful fission products as well as unused fuel. Thus, the spent fuel rods are reprocessed to recover unused fuel and to separate useful and harmful fission products. Among the above harmful fission products, ⁹⁰ Sr has a high fission yield (5.73% for U-235 as fuel), and its half-life is medium (28.8 years), which makes it easy for human bone and animal bone. It is the most biologically toxic species because it accumulates and causes blood cancer and bone cancer by high-energy b-ray emission. Therefore, the U.S. Environmental Protection Agency (EPA) has set ^{an upper limit for 90} Sr-induced radioactivity in drinking water at 8 pCi/L or 0.3 Bq/L, which in terms of chemical concentration is ⁹⁰ Sr-0.057 ppq ( parts per quadrillion) or 6.3 x 10 ^-16 M. ^{This means that virtually all 90} Sr must be removed from reprocessed liquid waste before being released into the environment. In this regard, the ⁹⁰ Sr concentration in the reprocessed liquid waste ranges from ˜7 ppt (parts per trillion) to 26 ppb (parts per billion). In fact, the ⁹⁰ Sr concentration of this lower limit (~7 ppt) itself is already a very low concentration to be removed from solution even when present as a single component in the solution. On the other hand, the reprocessed liquid waste usually contains ^{Na +} at a concentration exceeding 115,000 ppm (parts per million) or 5 M. Therefore, efforts have been focused to develop at least 630 billion times more ⁹⁰ Sr removing agent in the material from the treatment of waste solutions containing high concentrations of Na to extract the ⁹⁰ Sr of ~ 7 ppt than ⁹⁰ Sr. The ⁹⁰ Sr removal agent must also have radiation shielding properties to successfully perform ^{the 90 Sr removal operation under such high radiation conditions.}

Based on the above background, various inorganic compounds have been investigated as ^{90 Sr scavengers.} They are titanosilicate (CST), layered metal chalcogenide (KMS-1), micas, metal substituted niobate, antimony silicate, titanate, and manganese oxide. However, with the exception of KMS-1, titanate, and CST, the Sr ²⁺ removal ability of other materials was evaluated under low Na concentration conditions. Even in the above three exceptional cases, although their performance was evaluated under highly concentrated Na condition (> 5 M), the tested initial Sr ²⁺ concentration (24 ppb to 20 ppm) was actually ⁹⁰ Sr in reprocessed liquid waste. much higher than the lower limit of concentration (~7 ppt). Thus, to date, while close to the ⁹⁰ Sr concentration ~ 7 ppt was no material that exhibits the ability to remove the ⁹⁰ Sr from the solution than the concentration of Na ⁺ 5 M. We report a novel layered vanadosilicate material, SGU-7, which exhibits the highest ability to capture ⁹⁰ Sr from a concentration of 6.2 ppt or 6.8x10 ^-11 M in a 5 M Na ^{+ solution.}

Akhilesh Tripathi, Timothy Hughbanks, and Abraham Clearfield disclose the first frameworks composed of vanadosilicate clusters [Akhilesh Tripathi, Timothy Hughbanks, and Abraham Clearfield, "The First Framework Solid Composed of Vanadosilicate Clusters", J. Am . Chem. Soc. 125, 35, pp. 10528 - 10529, (2003)].

Herein, Sr ²⁺ ion adsorbent, the Sr ²⁺ ion method of removing Sr ²⁺ ions by using an adsorbent, tea bags for drinking water purification including the Sr ²⁺ ion adsorbent, and polluted water treatment using the layered silicate Bar I it's about how

However, the problems to be solved by the present application are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

A first aspect of the present disclosure provides an ^{Sr 2+ ion adsorbent comprising a layered vanadosilicate.}

A second aspect of the present disclosure is ^{a method for removing Sr 2+} ions from contaminated water to be removed ^{Sr 2+ ions comprising 50 ppm or less of Sr 2+} ions and one or more other competing metal ions, wherein the one or more other competing metal ions There is provided a method for removing ^{Sr 2+} ions, comprising using ^{the Sr 2+} ion adsorbent according to the first aspect, wherein the total concentration of ions is at least 1 M.

A third aspect of the present application provides a tea bag for purifying drinking water, comprising the ^{Sr 2+} ion adsorbent ^{according to the first aspect and a container accommodating the Sr 2+ ion adsorbent, but through which the ions can pass.}

The fourth aspect of the present application, there is provided a Sr ²⁺ using an ion adsorbent for removing Sr ²⁺ ions, polluted water treatment method according to the first aspect.

According to the embodiments of the present application, layered vanadosilicate is provided as a material capable of adsorbing ^{Sr 2+} ions mixed in a solution of highly concentrated competing metal ions (eg, Na ^{+ ).}

In accordance with implementations of the present embodiment, the layered bar I With Sr ²⁺ ion adsorbent comprising a silicate to remove Sr ²⁺ ions in an effective and a very high rate from the ground water and soil contamination due to Sr ²⁺ ions have.

According to embodiments herein, a novel layered vanadosilicate material, SGU-7, has an excellent ability to trap ^{Sr 2+} ions from a concentration ^{of 6.2 ppt or 6.8x10 -11 M in a 5 M Na solution.}

^{The capture of traces of 90 Sr (parts per trillion or ppt level) from highly concentrated Na +} (5 M or 115,000 ppm) liquid waste produced from the reprocessing of spent nuclear fuel rods is essential for the continuous operation of nuclear power plants. It is important. However, none of the adsorbents showed such capabilities. According to embodiments herein, we present a novel layered layer with unit cell parameters of a =23.58 Å, b =30.04 Å, c =12.31 Å, β =100.2°, and a space group of P 12 ₁ / a 1 . It was found that the vanadosilicate, SGU-7, can effectively trap ⁹⁰ Sr from a 5 M Na ^{+ solution containing 6.2 ppt of 90 Sr.} SGU-7 can also ^{effectively capture 1-ppb levels of 226} Ra from 2 M NaCl solution, and Cs ⁺ and Sr ²⁺ from groundwater, so that it can effectively trap groundwater and soil contaminated with ²²⁶ Ra, ⁹⁰ Sr, and ^{137 Cs.} can be used immediately to improve

1 is an SEM, TEM image and diffraction data of SGU-7 samples for structural analysis. FIG. 1a is a typical SEM image of Na(95)-SGU-7 in the form of a plate, and FIG. 1b is a Fourier diffractogram (Fourier). An angular dark field (ADF) image and a simulated ADF image according to [010] using a diffractogram), in which a red sphere indicates the position of a V atom. 1c is a synchrotron powder x-ray diffraction (PXRD) pattern of Na(95)-SGU-7 and Sr(95)-SGU-7; 1d to 1f are 3D (EDF) data projection images observed according to Na(95)-SGU-7, Ca(82)-SGU-7 and Sr(95)-SGU-7 [001], respectively.
2 is a scanning transmission electron microscope (STEM) image and energy dispersive spectrometry (EDS) analysis image of Na-SGU-7 according to [010], wherein FIG. 2(a) is a low magnification ADF, FIG. 2(b) is a red color Experimental high-resolution ADF image using the intensity profile according to the arrow, FIG. 2(c) is a high-resolution ADF image simulated using the intensity profile, FIG. 2(d) is an experimental ADF image, FIG. 2(e) an experimental ABF image, and FIG. 2(f) is the EDS spectrum, where the insets in FIGS. 2(d) and 2(e) are the filtered images (overlaid with the atomic structural model) after applying p 2 symmetry. Oxygen and cations in the structural model are omitted for clear comparison, and Cu, Fe, and Co in the EDS spectrum occur in the device, grid, and holder.
Figure 3 is a high resolution transmission electron microscopy (HRTEM) image of Na-SGU-7, Figure 3 (a) is [100], Figure 3 (b) is [010], Figure 3 (c) ) is [001], and FIG. 3(d) is an image taken along different domain axes of [101], FIG. 3(e) is an image showing the shape of a hexagonal 2D nanosheet with the indicated crystal axis, and FIG. 3 (f) is the corresponding TEM image from the indicated area.
4 is an image analyzed using 3D-EDT (3-dimensional electron diffraction tomography) data for the crystal structures of Na-SGU-7 and Sr(95)-SGU-7 and precisely analyzed for synchrotron PXRD data. 4(a) and 4(c) are atomic structure models of Na-SGU-7 and Sr-SGU-7 analyzed using 3D EDT data, respectively, and FIGS. 4(b) and 4(d) are synchrotron As structural models of Na-SGU-7 and Sr-SGU-7 analyzed precisely for PXRD data, blue and yellow polyhedrons represent VO ₆ and SiO ₄ , respectively, and purple and green spheres represent Na and Sr ions, respectively. Here, green and white mixed spheres indicate site occupancy less than 1, and water molecules are not shown for clarity.
5 is a detailed analysis image of Na-SGU-7 and Sr(95)-SGU-7, and FIG. 5(a) is a detailed analysis result of Rietveld analysis of Na-SGU-7 (inset shows peak shape anisotropy; Precision analysis result: R _exp =0.026, R _p =0.06, R _wp =0.086, R _bragg = 0.042), and FIG. 5(b) is a detailed analysis of the structural model of Na-SGU-7. 5(c) is a Rietveld precision analysis result of Sr(95)-SGU-7 sample (R _exp =0.027, R _p =0.057, R _wp =0.077, R _bragg =0.036), FIG. 5(d) is a precisely analyzed structural model of Sr(95)-SGU-7 (yellow: Na, cyan: Sr and red: O. Some cations are white in part due to shared occupancy).
6 is a schematic diagram of well-defined pentanuclear vanadate (V ₅ ) chains, FIG. 6(a) is _{a schematic diagram of V 5} chains arranged in each sheet, and FIG. 6(b) is a schematic diagram of _{V 5 chains} .
7 is a crystal structural model of Na-SGU-7, (a) [101], (b) and (c) the crystal structure of Na-SGU-7 according to the [010] orientation, and the cations are is omitted, and the green, blue and red spheres represent vanadium, silicon and oxygen atoms, respectively.
^{8 shows radioactive 90} Sr and ²²⁶ Ra from highly concentrated Na ⁺ nuclear waste solutions. As capture data, FIG. 8(a) shows the log K _d of Na-SGU-7 with known reference materials obtained from a 5 M Na ^{+ solution containing 35 ppb of Sr 2+ at an initial pH=14.} , K _d and comparative data of the degree of ion exchange (top of each bar), and Figure 8(b) is Na-SGU-7 and Na-CST from a 2 M Na ^{+ solution containing 5.4 ppt of 90 Sr under neutral conditions.} is ^{the comparative data of 90} Sr- trapping ability, and FIG. 8(c) is a ^{comparison of the radioactive 90} Sr trapping function of Na-SGU-7 and Na-CST from a 5 M Na ^{+ solution containing 6.2 ppt of 90 Sr under neutral conditions.} data, and Figure 8(d) is a comparison data of ^{the radioactive 226} Ra trapping ability of Na-SGU-7 and Na-4-Mica in a 2 M Na ^{+ solution containing 1.1 ppb of 226} Ra (5×10 ^{-9 M),} All the above experiments were performed under the condition of 1 L/g.
9 is ^{Sr 2+} and Cs ^{+ removal and kinetic data of Sr 2+} ion exchange with Na-SGU-7 in simulated groundwater, and FIG. 9(a) is Na-SGU-7 and known in simulated groundwater. Log K _d , K _d and ion exchange degree comparison data of Sr ²⁺ adsorbent, FIG. 9(b) shows Na-SGU-7 under 1 L/g condition with ^{[Sr 2+} ] _{i = 42 ppb after 12 hours.} used to Sr ^2+, Ca ^2+, Mg ²⁺ and K ⁺ and Na ⁺ removal from the increase in the ground water is a plot of (% of the initial amount of each cation), Figure 9 (c) are [Sr ^2+] _i = 1.03 ppm in 1 L / g of Na-SGU-7 Sr ²⁺ concentration with time for Sr ²⁺ removal (left y-axis, and the red curve) and Sr ²⁺ removed (right y-axis by performed under conditions and blue curve). ^{In addition, FIG. 9(d) shows the degree of Sr 2+} removal by Na = SGU-7 and the corresponding log K ^{for [Sr 2+} ] _i of 0.043 ppm to 31 ppm under the condition of 1 L/g groundwater with pH = 7. _d , and FIG. 9(e) is a ^{plot of Sr 2+} uptake by Na-SGU-7 versus pH during ^{Sr 2+} removal under 1-equivalent conditions ^{with [Sr 2+} ] _i = 1.03 ppm (mg/g) ), and FIG. 9(f) shows ^{Sr 2+} removal from groundwater by Na-SGU-7 for pH (3, 7, 13 and 14) under 1 L/g condition ^{with [Sr 2+} ] _{i = 1.03 ppm.} It is a plot in degrees (%). Also, Fig. 9(g) shows Sr ^{from a 5 M Na +} solution with Na-SGU-7 for pH (3, 7, 13 and 14) under 1 L/g condition ^{with [Sr 2+} ] _{i = 1.03 ppm.} ²⁺ is a plot of the degree of removal (%), and FIG. 9(h) is log from groundwater under the condition of 1 L/g ^{for [Cs +} ] _i ^{for each case of [Cs +} ] _i = 8 ppb and 24 ppb. Plots of K _d values and Cs ⁺ degree of rejection.
10 is data regarding the stability of Na-SGU-7 under acidic and basic conditions, FIG. 10(a) is an SEM image of pure Na-SGU-7, and FIG. 10(b) is acidic (pH=3) ) after immersion in the solution for 12 hours, FIG. 10(c) is after immersion in a basic solution of pH=13 for 12 hours and FIG. 10(d) is Na-SGU- after immersion in a basic solution of pH=14 for 12 hours. 7 SEM images, and FIG. 10(e) is an X-ray diffraction pattern corresponding to them.
11 is As data on the effect of pH on the performance of Na-SGU-7 and Na-CST, Fig. 11(a) is [Sr ²⁺ ] ^{Sr 2+} removal degree from groundwater with Na-SGU-7 as ^{the Sr 2+} -scavenger for pH (3, 7, 13, and 14) under 1 L/g condition with _{i = 1.03 ppm} is a plot of (%), and FIG. 11(b) is ^{the Sr 2+} − Na as a scavenger with respect to pH (3, 7, 13, and 14) under 1 L/g condition ^{with [Sr 2+} ] _{i =1.03 ppm.} A plot of Sr ²⁺ removal (%) from a 5 M Na ^{+ solution with -CST-7.}

Hereinafter, with reference to the accompanying drawings, embodiments and examples of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily carry out. However, the present application may be embodied in several different forms and is not limited to the embodiments and examples described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout this specification, when a part is "connected" with another part, this includes not only the case where it is "directly connected" but also the case where it is "electrically connected" with another element interposed therebetween. do.

Throughout this specification, when a member is said to be located “on” another member, this includes not only a case in which a member is in contact with another member but also a case in which another member is present between the two members.

Throughout this specification, when a part "includes" a certain element, it means that other elements may be further included, rather than excluding other elements, unless otherwise stated.

As used herein, the terms "about," "substantially," and the like are used in a sense at or close to the numerical value when the manufacturing and material tolerances inherent in the stated meaning are presented, and to aid in the understanding of the present application. It is used to prevent an unconscionable infringer from using the mentioned disclosure in an unreasonable way.

As used throughout this specification, the term “step of doing” or “step of” does not mean “step for”.

Throughout this specification, the term "combination(s) of these" included in the expression of the Markush form means one or more mixtures or combinations selected from the group consisting of the components described in the expression of the Markush form, It means to include one or more selected from the group consisting of the above components.

Throughout this specification, reference to “A and/or B” means “A or B, or A and B”.

Throughout this specification, “ppm” refers to parts per million (10 ⁻⁶ ) as a concentration unit of a solution, and “ppb” refers to parts per billion (10 ⁻⁹ ) as a concentration unit for a solution. means, "ppt" as a concentration unit of a solution means parts per trillion (parts per trillion, 10 ^-12 ), "ppq" as a concentration unit of a solution, 1,000 trillion parts (parts per quadrillion, 10 ^-15 ) means

Hereinafter, embodiments of the present application have been described in detail, but the present application may not be limited thereto.

A first aspect of the present disclosure provides an ^{Sr 2+ ion adsorbent comprising a layered vanadosilicate.}

In one embodiment of the present application, the layered vanadosilicate may have a microporous structure.

In one embodiment of the present application, the layered vanadosilicate may include ^{V ( IV) which is vanadium having an oxidation number of +4.}

In one embodiment of the present application, the ^{layered vanadosilicate including V ( IV)} , which is vanadium having an oxidation number of +4, may be represented by the following formula (1):

[Formula 1]

In Formula 1,

M is at least one selected from Na, Li, and K, and 0≤a≤5; 1≤b; and d = 2 (b+c+10).

In one embodiment of the present application, M may be one or more alkali metals selected from Na, Li, and K, but is not limited thereto. In one embodiment of the present application, M may be Na.

, b=30.04 Å, c=12.31 Å, β=100.2°의 단위 셀 파라미터, 및 P12₁/a1의 공간 그룹을 갖는 것일 수 있다. In one embodiment of the present application, the layered vanadosilicate is a = 23.58

, b = 30.04 Å, c = 12.31 Å, unit cell parameters of β = 100.2°, and a space group of P 12 ₁ / a 1 .

^{In one embodiment of the present application, the layered vanadosilicate comprising V ( IV)} which is vanadium having an oxidation number of +4 according to Formula 1 is vanadium having an oxidation number of +5 according to Formula 2 below ^(V) It may be obtained by reducing a vanadosilicate comprising, but is not limited thereto:

[Formula 2]

In Formula 2,

M is at least one selected from Na, Li, and K, 0≤a'≤5; 1≤b′; and d′=2(b′+c′+10).

In one embodiment of the present application, M may be one or more alkali metals selected from Na, Li, and K, but is not limited thereto. In one embodiment of the present application, M may be Na.

In one embodiment of the present application, the vanadosilicate containing V ^(V) , which is vanadium having an oxidation number of +5 according to Formula 2, is reduced with an organic reducing agent and/or an inorganic reducing agent to obtain +4 according to Formula 1 It may be to prepare a layered vanadosilicate including ^{V ( IV)} , which is vanadium having an oxidation number, but is not limited thereto. Here, the organic reducing agent is a carboxyl group, a hydroxyl group, an aldehyde group, an amine group, a sulfite group, a bisulfite group, a carbonate group, a bicarbonate group, a phosphorous acid group, a hypophosphorous acid group, a thiol group, a cyan group, a thiocyanate group, It may include at least one organic reducing agent having a functional group selected from the group consisting of an ammonium group, a hydrazinyl group, a borohydride group, an amide group, a silane group, an amino group, a carbamoyl group, a urea group, and combinations thereof. A non-limiting example of the organic reducing agent may be oxalic acid, but is not limited thereto. Non-limiting examples of the inorganic reducing agent include inorganic acids, halogen salts of metals, thiosulfate salts of metals, sulfite salts of metals, bisulfite salts of metals, ferrites, sulfites of metals, metal hydrides, metal borohydrides , including those selected from the group consisting of ammonium salts of metals, persulfates of metals, periodic salts of metals, hypophosphorous acid, ammonium hypophosphite, hypophosphite of metals, ethylenediaminetetraacetic acid salts of metals, and combinations thereof may be, but is not limited thereto.

In one embodiment of the present application, in Formula 1, M ⁺ and/or H ⁺ may be substituted by aqueous ion-exchange with the corresponding divalent cation, Sr ^{2+, but is not limited thereto.} In one embodiment of the present application, the layered ^{vanadosilicate may be more stable after Sr 2+} ion-exchange than before Sr ²⁺ ion-exchange, but is not limited thereto.

In one embodiment of the present application, the Sr ²⁺ ion to be adsorbed may be radioactive Sr.

In one embodiment of the present application, the Sr ²⁺ ion adsorbent may be in the form of a powder, a foam, a film, or a fixed bed column filled with the adsorbent, but is not limited thereto.

A second aspect of the present application is a method for removing ^{Sr 2+} ions from contaminated water to be removed ^{Sr 2+ ions comprising about 50 ppm or less of Sr 2+} ions and one or more other competing metal ions, wherein the one or more other competing metal ions are removed. There is provided a method for removing ^{Sr 2+} ions comprising using ^{the Sr 2+} ion adsorbent according to the first aspect, wherein the total concentration of metal ions is from about 1 M to about 8 M.

Although a detailed description of overlapping parts with the first aspect of the present application is omitted, the contents described for the first aspect of the present application may be equally applied even if the description thereof is omitted in the second aspect of the present application.

In one embodiment of the invention, the Sr ²⁺ ion removal the concentration of Sr ²⁺ ions contained in the target can be up to about 50 ppm contamination. However, without being limited thereto. ^{The concentration of Sr 2+} ions included in the Sr ²⁺ ion removal target contaminated water may be 30 ppm or less, but is not limited thereto. ^{The concentration of Sr 2+} ions included in the Sr ²⁺ ion removal target contaminated water is about 50 ppm or less, about 40 ppm or less, about 30 ppm or less, about 20 ppm or less, about 10 ppm or less, about 5 ppm or less, about 1 ppm or less, about 900 ppb or less, about 800 ppb or less, about 700 ppb or less, about 600 ppb or less, about 500 ppb or less, about 400 ppb or less, about 300 ppb or less, about 200 ppb or less, about 100 ppb or less, about 50 ppb or less, about 40 ppb or less, about 30 ppb or less, about 20 ppb or less, about 10 ppb or less, about 5 ppb or less, about 1 ppb or less, about 900 ppt or less, about 800 ppt or less, about 700 ppt or less, about 600 ppt or less, about 500 ppt or less, about 400 ppt or less, about 300 ppt or less, about 200 ppt or less, about 100 ppt or less, about 50 ppt or less, about 45 ppt or less, about 40 ppt or less, about 35 ppt or less, about 30 ppt or less, about 25 ppt or less, about 20 ppt or less, about 15 ppt or less, about 10 ppt or less, about 9 ppt or less, about 8 ppt or less, about 7 ppt or less, about 6 ppt or less, about 5 ppt or less, about 4 ppt or less, about 3 ppt or less, about 2 ppt or less, or about 1 ppt or less, but is not limited thereto.

In one embodiment of the present application, the ^{total concentration of the one or more other competing metal ions included in the Sr 2+} ion removal target contaminated water may be about 1 M to about 8 M, but is not limited thereto. In one embodiment of the present application, the ^{total concentration of the one or more other competing metal ions included in the Sr 2+} ion removal target contaminated water is about 2 M to about 6 M of the total concentration of the one or more other competing metal ions may be, but is not limited thereto. The total concentration of the one or more other competing metal ions included in the Sr ²⁺ ion removal target contaminated water is about 1 M to about 8 M, about 1 M to about 7 M, about 1 M to about 6 M, about 1 M to about 5 M, about 1 M to about 4 M, about 1 M to about 3 M, about 1 M to about 2 M, about 2 M to about 8 M, about 2 M to about 7 M, about 2 M to about 6 M, about 2 M to about 5 M, about 2 M to about 4 M, about 2 M to about 3 M, about 3 M to about 8 M, about 3 M to about 7 M, about 3 M to about 6 M , about 3 M to about 5 M, about 3 M to about 4 M, about 4 M to about 8 M, about 4 M to about 7 M, about 4 M to about 6 M, about 4 M to about 5 M, about 5 M to about 8 M, about 5 M to about 7 M, about 5 M to about 6 M, about 6 M to about 8 M, about 6 M to about 7 M, about 7 M to about 8 M, However, the present invention is not limited thereto.

In one embodiment of the present application, ^{the pH of the contaminated water to be removed Sr 2+} ions may be about 3 to about 14, but is not limited thereto. The pH of the Sr ²⁺ ion removal target contaminated water is about 3 to about 14, about 3 to about 13, about 3 to about 12, about 3 to about 11, about 3 to about 10, about 3 to about 9, about 3 to about 8, about 3 to about 7, about 3 to about 6, about 3 to about 5, about 3 to about 4, about 4 to about 14, about 4 to about 13, about 4 to about 12, about 4 to about 11, about 4 to about 10, about 4 to about 9, about 4 to about 8, about 4 to about 7, about 4 to about 6, about 4 to about 5, about 5 to about 14, about 5 to about 13, about 5 to about 12, about 5 to about 11, about 5 to about 10, about 5 to about 9, about 5 to about 8, about 5 to about 7, about 5 to about 6, about 6 to about 14, about 6 to about 13, about 6 to about 12, about 6 to about 11, about 6 to about 10, about 6 to about 9, about 6 to about 8, about 6 to about 7, about 7 to about 14, about 7 to about 13, about 7 to about 12, about 7 to about 11, about 7 to about 10, about 7 to about 9, about 7 to about 8, about 8 to about 14, about 8 to about 13, about 8 to about 12, about 8 to about 11, about 8 to about 10, about 8 to about 9, about 9 to about 14, about 9 to about 13, about 9 to about 12, about 9 to about 11, about 9 to about 10, about 10 to about 14, about 10 to about 13, about 10 to about 12, about 10 to about 11, about 11 to about 14, about 11 to about 13, about 11 to about 12, about 12 to about 14, about 12 to about 13, or about 13 to about 14, but is not limited thereto. When the pH of the contaminated water to be removed from ^{Sr 2+ ions is less than about 3, the absorption or removal degree of Sr 2+} may rapidly decrease, but is not limited thereto.

In one embodiment of the present application, the competing metal ion may be at least one selected from ^{Na +} , Ca ²⁺ , Mg ²⁺ , and K ^{+ , but is not limited thereto.}

In one embodiment of the present application, the Sr ²⁺ ion adsorbent includes a layered vanadosilicate, and the layered vanadosilicate may have a microporous structure.

In one embodiment of the present application, the layered vanadosilicate may include ^{V ( IV) which is vanadium having an oxidation number of +4.}

In one embodiment of the present application, the ^{layered vanadosilicate including V ( IV)} , which is vanadium having an oxidation number of +4, may be represented by the following formula (1):

[Formula 1]

In Formula 1,

M is at least one selected from Na, Li, and K, and 0≤a≤5; 1≤b; and d = 2 (b+c+10).

In one embodiment of the present application, M may be one or more alkali metals selected from Na, Li, and K, but is not limited thereto. In one embodiment of the present application, M may be Na.

In one embodiment of the present application, the layered vanadosilicate has a unit cell parameter of a = 23.58 Å, b = 30.04 Å, c = 12.31 Å, β = 100.2°, and a space group of P 12 ₁ / a 1 . it could be

In one embodiment of the present application, the layered vanadosilicate according to Formula 1 may be obtained by reducing a vanadosilicate containing V ^{(V), which is vanadium having an oxidation number of +5 according to Formula 2 below,} It is not limited to:

[Formula 2]

In Formula 2,

M is at least one selected from Na, Li, and K, 0≤a'≤5; 1≤b′; and d′=2(b′+c′+10).

In one embodiment of the present application, M may be one or more alkali metals selected from Na, Li, and K, but is not limited thereto. In one embodiment of the present application, M may be Na.

In one embodiment of the present application, in Formula 1, M ⁺ and/or H ⁺ may be substituted by aqueous ion-exchange with the corresponding divalent cation, Sr ^{2+, but is not limited thereto.} In one embodiment of the present application, the layered vanadosilicate included in ^{the Sr 2+ ion adsorbent may be more stable after Sr 2+} ion-exchange than before Sr ²⁺ ion-exchange, but is not limited thereto.

In one embodiment of the present application, the Sr ²⁺ ion to be adsorbed may be radioactive Sr.

In one embodiment of the present application, the Sr ²⁺ ion adsorbent may be in the form of a powder, a foam, a film, or a fixed bed column filled with the adsorbent, but is not limited thereto.

A third aspect of the present application provides a tea bag for purifying drinking water, comprising a container accommodating ^{the Sr 2+} ion adsorbent and the Sr ^{2+ ion adsorbent according to the first aspect, wherein the ions are permeable.}

Although detailed descriptions of parts overlapping with the first and second aspects of the present application are omitted, the descriptions of the first and second aspects of the present application are equally applicable even if the description is omitted in the third aspect of the present application. can

In one embodiment of the present application, the drinking water purification tea bag may be for removing radioactive Sr in drinking water, but is not limited thereto.

In one embodiment of the present application, the container included in the tea bag for purifying drinking water may be in the form of a nonwoven fabric or a form of plastic, but is not limited thereto.

In one embodiment of the present application, the Sr ²⁺ ion adsorbent includes a layered vanadosilicate, and the layered vanadosilicate may have a microporous structure.

In one embodiment of the present application, the layered vanadosilicate may include ^{V ( IV) which is vanadium having an oxidation number of +4.}

In one embodiment of the present application, the ^{layered vanadosilicate including V ( IV)} , which is vanadium having an oxidation number of +4, may be represented by the following formula (1):

[Formula 1]

In Formula 1,

M is at least one selected from Na, Li, and K, and 0≤a≤5; 1≤b; and d = 2 (b+c+10).

In one embodiment of the present application, M may be one or more alkali metals selected from Na, Li, and K, but is not limited thereto. In one embodiment of the present application, M may be Na.

In one embodiment of the present application, the layered vanadosilicate has a unit cell parameter of a = 23.58 Å, b = 30.04 Å, c = 12.31 Å, β = 100.2°, and a space group of P 12 ₁ / a 1 . it could be

^{In one embodiment of the present application, the layered vanadosilicate comprising V ( IV)} which is vanadium having an oxidation number of +4 according to Formula 1 is vanadium having an oxidation number of +5 according to Formula 2 below ^(V) It may be obtained by reducing a vanadosilicate comprising, but is not limited thereto:

[Formula 2]

In Formula 2,

M is at least one selected from Na, Li, and K, 0≤a'≤5; 1≤b′; and d′=2(b′+c′+10).

In one embodiment of the present application, M may be one or more alkali metals selected from Na, Li, and K, but is not limited thereto. In one embodiment of the present application, M may be Na.

In one embodiment of the present application, in Formula 1, M ⁺ and/or H ⁺ may be substituted by aqueous ion-exchange with the corresponding divalent cation, Sr ^{2+, but is not limited thereto.} In one embodiment of the present application, the layered vanadosilicate included in ^{the Sr 2+ ion adsorbent may be more stable after Sr 2+} ion-exchange than before Sr ²⁺ ion-exchange, but is not limited thereto.

In one embodiment of the present application, the Sr ²⁺ ion to be adsorbed may be radioactive Sr.

In one embodiment of the present application, the Sr ²⁺ ion adsorbent may be in the form of a powder, a foam, a film, or a fixed bed column filled with the adsorbent, but is not limited thereto.

The fourth aspect of the present application, there is provided a Sr ²⁺ using an ion adsorbent for removing Sr ²⁺ ions, polluted water treatment method according to the first aspect.

Although detailed descriptions of parts overlapping with the first to third aspects of the present application have been omitted, the descriptions of the first to third aspects of the present application will be equally applied even if the description is omitted from the fourth aspect of the present application. can

In one embodiment of the present application, the contaminated water may be groundwater, seawater, or a nuclear waste solution, but is not limited thereto.

In one embodiment of the present application, the Sr ²⁺ ion adsorbent includes a layered vanadosilicate, and the layered vanadosilicate may have a microporous structure.

In one embodiment of the present application, the layered vanadosilicate may include ^{V ( IV) which is vanadium having an oxidation number of +4.}

In one embodiment of the present application, the ^{layered vanadosilicate including V ( IV)} , which is vanadium having an oxidation number of +4, may be represented by the following formula (1):

[Formula 1]

In Formula 1,

M is at least one selected from Na, Li, and K, and 0≤a≤5; 1≤b; and d = 2 (b+c+10).

In one embodiment of the present application, M may be one or more alkali metals selected from Na, Li, and K, but is not limited thereto. In one embodiment of the present application, M may be Na.

In one embodiment of the present application, the layered vanadosilicate has a unit cell parameter of a = 23.58 Å, b = 30.04 Å, c = 12.31 Å, β = 100.2°, and a space group of P 12 ₁ / a 1 . it could be

^{In one embodiment of the present application, the layered vanadosilicate comprising V ( IV)} which is vanadium having an oxidation number of +4 according to Formula 1 is vanadium having an oxidation number of +5 according to Formula 2 below ^(V) It may be obtained by reducing a vanadosilicate comprising, but is not limited thereto:

[Formula 2]

In Formula 2,

M is at least one selected from Na, Li, and K, 0≤a'≤5; 1≤b′; and d′=2(b′+c′+10).

In one embodiment of the present application, M may be one or more alkali metals selected from Na, Li, and K, but is not limited thereto. In one embodiment of the present application, M may be Na.

In one embodiment of the present application, in Formula 1, M ⁺ and/or H ⁺ may be substituted by aqueous ion-exchange with the corresponding divalent cation, Sr ^{2+, but is not limited thereto.} In one embodiment of the present application, the layered vanadosilicate included in ^{the Sr 2+ ion adsorbent may be more stable after Sr 2+} ion-exchange than before Sr ²⁺ ion-exchange, but is not limited thereto.

In one embodiment of the present application, the Sr ²⁺ ion to be adsorbed may be radioactive Sr.

In one embodiment of the present application, the Sr ²⁺ ion adsorbent may be in the form of a powder, a foam, a film, or a fixed bed column filled with the adsorbent, but is not limited thereto.

Hereinafter, the present application will be described in more detail using examples, but the following examples are only illustrative to help the understanding of the present application, and the content of the present application is not limited to the following examples.

[Example]

1. Sr ²⁺ Preparation of Adsorbents and Related Materials

(1) Substances used

sodium silicate solution I (17% to 19% Na ₂ O, and 35% to 38% SiO ₂ , Kanto), sodium silicate solution II (10.6% Na ₂ O, and ˜26.5% SiO ₂ , Sigma-Aldrich), sodium Silicate solution III (27% SiO ₂ , 8% Na ₂ O, Merck), tetraethyl orthosilicate (Si(OC ₂ H ₅ ) ₄ , 98%, Acros), vanadium(V) oxide (V ₂ O ₅ , 99 %, Aldrich), titanium isopropoxide [Ti(OC ₃ H ₇ ) ₄ , 98%, Junsei], TiCl ₃ solution (20% in 3% HCl, Alfa Aesar), TiCl ₃ solution (10% m/m 15% m/m TiCl ₃ solution in HCl, Merck), copper sulfate pentahydrate (CuSO ₄ ·5H ₂ O, 99%, Alfa-Aesar), oxalic acid dihydrate (H ₂ O ₄ C ₂ ·2H ₂ O 99% , Sigma-Aldrich), sulfuric acid (H ₂ SO ₄ , 95%, Duksan), hydrochloric acid (HCl, 36.5% to 38.0%, Sigma-Aldrich), sodium hydroxide (NaOH, 93%, Samchun), sodium chloride ( NaCl, 99%, Samchun), Potassium Chloride (KCl, 99%, Oriental), Potassium Fluoride (KF, 95%, Samchun), Strontium Chloride Hexahydrate (SrCl ₂ 6H ₂ O, 98.5%, Samchun), Potassium Carbonate (K ₂ CO ₃ , 99%, Aldrich), manganese powder, (Mn, 325 mesh, 99.3%, metal based, Alfa Aesar), tin powder (Sn, <150 μm, 99.5% trace metal based, Sigma-Aldrich) ), sulfur powder (S, 98%, Junsei), sodium tetraphenylborate (NaTPB, 99.5%, Acros), ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA, 99% to 101%, Sigma-Aldrich), ethanol (EtOH, 95%, SK), phlogopite mica (K-PMica, near Perth, Ontario, Canada) was purchased and used without further purification.

(2) Preparation of Na-SGU-7

Na ₂ SiO ₃ , V ₂ O _5, oxalic acid, NaOH, NaCl and H ₂ O (distilled and deionized water) was prepared a gel (gel) formed, wherein the molar ratio of the synthetic gel SiO ₂ : V ₂ O ₅ : H ₂ C ₂ O ₄ : Na ₂ O: NaCl: H ₂ O as 5.49: 1: 3.67: 5.30: 9.99: 365. The gel was prepared as follows.

Preparation of silicon source solution : NaOH solution (3 g NaOH and 20 g H ₂ O) was mixed with 12.2 g Na ₂ SiO ₃ (17% to 19% Na ₂ O, and 35% to 38%, SiO _2, Kanto) and 12 g of water was added to the formed sodium silicate solution. NaCl solution (8 g NaCl and 33 g water) was added to the mixture and the mixture was stirred vigorously.

Preparation of Vanadium Source Solution : Oxalic acid (6.4 g) was added to a 100 mL round bottom flask containing water (25 g) and heated until the oxalic acid was dissolved. Then V ₂ O ₅ (2.5 g) was added to the flask. The heterogeneous mixture was heated for 20 minutes, at which time the yellow V ₂ O ₅ powder was completely dissolved in the solution and the solution turned greenish blue. The greenish blue V source solution was cooled to room temperature and then gradually added to the sodium silicate solution. The mixture was very viscous; Therefore, the mixture was homogenized using a spatula and stirring was continued. After aging at room temperature for 15 hours, the gel was transferred to a 50 mL Teflon-lined autoclave and placed in a preheated oven at 220° C. for 40 hours under static conditions. Purple crystals were collected by centrifugation, washed with a large amount of water, and finally washed with ethanol and dried at 80° C. for 3 hours.

(3) Preparation of Na-CST (sodium crystalline silicon titanate, Na ₂ Ti ₂ SiO ₇ ・2H ₂ O)

The sodium form (Na-CST) of crystalline silicon titanate was synthesized according to a known procedure. The gel was prepared by mixing titanium isopropoxide [Ti(OC ₃ H ₇ ) ₄ ] and tetraethyl orthosilicate [TEOS, Si(OC ₂ H ₅ ) _{4 ] in a plastic beaker.} Titanium isopropoxide (4.56 g) was mixed with 3.33 g of TEOS, wherein the Ti:Si molar ratio was 1:1. NaOH solution (6.32 M, 26 mL) was added to the mixture with vigorous stirring as a white powder precipitated. The heterogeneous mixture was stirred at room temperature for 4 hours and then transferred to a 65 mL Teflon-lined autoclave using 15 mL of distilled deionized water. The autoclave was then placed in a preheated oven at 170° C. for 10 days. The solid was collected by centrifugation, washed with a large amount of water, and then dried at 100° C. for 1 hour.

(4) Preparation of H-CST (hydrogen crystalline silicon titanate, H ₂ Ti ₂ SiO ₇ ·xH ₂ O)

The sodium form of crystalline silicon titanate (Na-CST, Na ₂ Ti ₂ SiO ₇ .2H ₂ O) was converted to hydrogen crystalline silicon titanate _{according to a known procedure (H-CST, H 2} Ti ₂ SiO ₇ .xH) ₂ O). First, 500 mg of Na-CST powder was dispersed in 70 mL of 0.1 M HCl aqueous solution. The solution was stirred at room temperature for 1 h (300 rpm). The solid was collected by centrifugation, washed with a large amount of water, and then dried at 100° C. for 1 hour.

(5) Preparation of KMS-1 [K _2x Mn _x Sn _3-x S ₆ (x=0.5-0.95)]

KMS-1 was synthesized according to a known procedure. Briefly, a mixture was prepared by mixing the elements Sn (7.14 g), Mn (1.656 g), S (5.78 g), K ₂ CO ₃ (4.16 g), and water (40 mL). The mixture was stirred at room temperature for 1 hour and transferred to a Teflon-lined stainless-steel autoclave. The autoclave was placed in a preheated oven at 200° C. for 96 hours under static conditions. After the hydrothermal reaction, the autoclave was cooled naturally to room temperature. The brown polycrystalline product was collected by centrifugation, washed with water and dried at 60° C. for 6 hours.

(6) Preparation of K-depleted phlogopite mica by topotactic leaching

K-depleted phlogopite mica was prepared according to a known procedure. _{Briefly, large crystals of phlogopite mica [KMg 3} Si ₃ AlO ₁₀ (OH) ₂ , ideal formula] were obtained near Perth, Ontario, Canada. The crystals were broken into small pieces by hand and then crushed using a grinder in the presence of water. After grinding, the mica slurry was dispersed in water and allowed to settle for 1 hour. The supernatant solution containing the mica particles with a size smaller than 1 μm was collected for ^{Sr 2+ removal studies.} The phlogopite mica (size <1 μm, 3 g) was incubated with 1.0 M sodium chloride (NaCl), 0.2 N sodium tetraphenylborate (NaTPB), 0.01 M disodium ethylenediaminetetraacetic acid (EDTA) at 70° C. for 24 hours. It was stirred with 100 mL of a solution containing This procedure was repeated 4 times to confirm maximal removal of ^{K + from the galleries of mica.} The sample was collected by centrifugation and washed repeatedly with a solution containing 40% 0.5 M NaCl and 60% acetone (v/v) to remove the precipitated potassium tetraphenylborate (NaTPB) from the sample. After the initial washing, the K-depleted phlogopite [Na _0.90 K _0.1 Mg _1.75 Si _2.75 AlO _8.25 (OH) ₂ ] was washed with a large amount of deionized water to remove all incorporated NaCl, and then they were dried in air.

(7) Preparation of ETS-10

A silicon source solution was prepared by first dissolving _{Na 2} SiO ₃ (18.4 g, 17% to 19% Na ₂ O, and 35% to 38%, SiO ₂ , Kanto) in water (60 g). To this, NaOH solution (2.4 g NaOH and 20 g water) was added with vigorous stirring, and the mixture was stirred for 2 h. For the preparation of the titanium source solution, titanium isopropoxide (5.7 g), H ₂ SO ₄ (4.5 g), and water (35 g) were mixed together and heated at 100° C. for 90 minutes, and finally 10 mL of water was added to the mixture and cooled to room temperature. The titanium source solution was added dropwise to the silicon source solution, and the mixture was stirred for 1 hour. A diluted KF solution (1.2 g KF and 15 g water) was added to the mixture. The mixture was aged at room temperature for 16 hours, transferred to a Teflon-lined autoclave, and heated at 200° C. for 22 hours under static conditions. After the autoclave was cooled to room temperature, the crystals were collected by centrifugation and washed with plenty of water. Scanning electron microscopy (SEM) shows a typical crystal size of 200 nm to 300 nm, and these crystals can also be used as seeds for AM-6 and SGU-29 synthesis.

(8) Preparation of AM-6

Preparation of silicon source solution : NaOH solution (3 g NaOH and 20 g water) was mixed with 12.2 g Na ₂ SiO ₃ (17% to 19% Na ₂ O, and 35% to 38%, SiO ₂ , Kanto) and 40 g of water was added to the sodium silicate solution. A diluted KCl solution (3 g KCl and 10 g water) was added to the mixture and the mixture was stirred vigorously.

Preparation of Vanadium Source Solution : H ₂ SO ₄ (4.9 g) was added to a 100 mL round bottom flask containing water (10 g). Then, to the flask _{were sequentially added V 2} O ₅ (1.7 g) and EtOH (4 g). While the heterogeneous mixture turned into a blue solution, the mixture was refluxed for 40 minutes. The blue vanadium source solution was added dropwise to the silicon source solution. The mixture was aged at room temperature for 15 hours; Seed ETS-10 (50 mg) was added to the gel and the gel was transferred to a 50 mL Teflon-lined autoclave and placed in a preheated oven at 230° C. for 48 hours under static conditions. The precipitated pale yellow crystals were collected, washed and dried at 100° C. for 1 hour.

(9) Manufacture of SGU-29

SGU-29 was synthesized according to a known procedure. The silicon source by mixing sodium silicate (40 g, 10.6% Na ₂ O, and ˜26.5% SiO ₂ , Sigma-Aldrich), 1.3 g NaOH, 12 g KCl, 18.5 g NaCl, and 60 g water. A solution was prepared. The mixture was stirred vigorously (800 rpm) at room temperature for 3 h. A copper source solution was prepared by dissolving _{CuSO 4} ·5H ₂ O (9 g) in 30 g of water containing 1.2 g of H ₂ SO _{4 .} Then, the copper source solution was added dropwise to the sodium silicate solution. The mixture was aged at room temperature for 15 hours and the pH was adjusted to 10.66 (if necessary) by adding _{H 2} SO _{4 diluted in water.} The seed ETS-10 (100 mg) was added to the gel and the gel was transferred to the 50 mL Teflon-lined autoclave and placed in a preheated oven at 215° C. for 24 hours under static conditions. The precipitated pale purple crystals were collected by centrifugation at 8,000 rpm and washed with plenty of water. The sample was dried at 100° C. for 2 hours.

(10) Preparation of ETS-4

The gel composed of Na ₂ SiO ₃ , Ti[OCH(CH ₃ ) ₂ ] ₄ , H ₂ SO ₄ , NaOH, KF, and H ₂ O was prepared, wherein SiO ₂ : TiO ₂ : H ₂ SO ₄ : The molar ratios of the synthetic gels in terms of Na ₂ O: KF: H ₂ O are 5.3: 1: 2.11: 7.26: 0.95: 303, respectively. A silicon source solution was prepared by first dissolving 18.3 g of Na ₂ SiO ₃ solution (17% to 19% Na ₂ O, and 35% to 38%, SiO ₂ , Kanto) in 58 g of water. To this, a NaOH solution (4 g of NaOH and 20 g of water) was added with vigorous stirring, and the mixture was stirred for 2 hours. For the preparation of the titanium source solution, titanium isopropoxide (6 g), H ₂ SO ₄ (4.5 g), and water (20 g) were mixed together and heated at 100° C. for 90 minutes, and finally 10 mL H ₂ O was added to the mixture and cooled at room temperature. The titanium source solution was added dropwise to the silicon source solution, and the mixture was stirred for 1 hour. A diluted KF solution (1.2 g KF and 15 g water) was added to the mixture. The mixture was aged at room temperature for 16 hours, transferred to a Teflon-lined autoclave, and heated at 200° C. for 22 hours under static conditions. After the autoclave was cooled to room temperature, the crystals were collected by centrifugation, washed with a large amount of water and dried at 80° C. for 2 hours.

(11) Preparation of AM-1

AM-1 was synthesized according to a known procedure. Briefly, NaOH solution (2.85 g NaOH and 13 g water) was added to 20.1 g sodium silicate solution (27% SiO ₂ , 8% Na ₂ O, Merck) and the mixture was stirred for 10 min. Then 16.5 g of a TiCl ₃ solution (20% in 3% HCl, Alfa Aesar) was added dropwise. The mixture was stirred vigorously at room temperature for 5 hours, transferred to a Teflon-lined autoclave, and heated at 230° C. for 96 hours under static conditions. After the autoclave was cooled to room temperature, the crystals were collected by centrifugation, washed with a large amount of water and dried at 80° C. for 2 hours. to obtain crystals with a size of 0.5 μm to 1 μm; 100 mg of these AM-1 crystals were pulverized using a mortar and pestle, and added as seeds to the same starting gel to initiate a novel hydrothermal reaction at 230°C for 24 hours.

(12) Preparation of AM-4

AM-4 was synthesized according to a known procedure. NaOH solution (14.76 g NaOH and 39 g water) was added to 27.1 g sodium silicate solution (27% SiO ₂ , 8% Na ₂ O, Merck) and the mixture was stirred for 30 min. Then 27.1 g of TiCl ₃ solution (15% m/m TiCl ₃ solution in 10% m/m HCl, Merck) was added dropwise. The mixture was stirred at room temperature for 4 hours and transferred to a Teflon-lined autoclave. The hydrothermal reaction was performed at 230° C. for 96 hours under static conditions. The reaction mixture was cooled to room temperature, and the product was collected by centrifugation, washed with plenty of water and dried at 80° C. for 2 hours. to obtain crystals with a size of 1 μm to 2 μm; 100 mg of these AM-4 crystals were crushed using a mortar and pestle, and added as seeds to the same starting gel to initiate a novel hydrothermal reaction at 230°C for 24 hours.

(13) Preparation of NaX

^{Na +} and purchased zeolite X (Lot number 943196110142 from UOP) were ion exchanged by placing 1 g of zeolite X powder in a glass vial containing 90 mL of 1 M NaCl solution and then stirring at 70° C. for 120 min. This procedure was repeated twice. After ion-exchange, the sample was washed with plenty of water until the chloride test with _{AgNO 3 solution was negative.}

(14) Preparation of Ca(81)-SGU-7

^{Na-SGU-7 was ion exchanged with Ca 2+} by placing 1 g of SGU-7 powder in a glass vial containing 90 mL of 0.50 M aqueous CaCl ₂ solution followed by stirring at 70° C. for 180 min. This procedure was repeated 3 times to achieve the maximum degree of ion exchange.

(15) Preparation of Sr-SGU-7

^{Na-SGU-7 was ion-exchanged with Sr 2+} by placing 1 g of SGU-7 powder in a glass vial containing 90 mL of 0.25 M SrCl ₂ solution, followed by stirring at 70° C. for 180 minutes. This procedure was repeated three times. After ion exchange, the sample was washed with plenty of water until the chloride test with _{AgNO 3 solution was negative.}

2. Structural analysis of Na-SGU-7 (pure SGU-7), etc.

A scanning electron microscope (SEM) image of the obtained purple pure SGU-7 crystals showed that their morphology had an average size of 1.25 μm to 1.5 μm and a thickness of about 20 nm to 30 nm (see FIG. 1A ). This indicates that it has a thin pseudo-hexagonal plate. Because of the very thin plate shape of the crystal and the deep overlap of reflections in the powder XRD profile, it is difficult to even obtain unit-cell parameters with powder XRD. 3D-EDT made it possible to analyze the structure of SGU-7, which will be described later in detail. A high-resolution scanning transmission electron microscope (STEM) ADF image of pure SGU-7 is shown in Fig. 1b. In ADF mode, the heavier atoms must appear brighter than the lighter atoms, as the contrast depends on the thickness of the sample and the atomic number of the element forming the structure. Figure 1b shows the crystal of the [010] orientation. According to this projection, the observed contrast is mainly related to the presence of the Si and V atomic columns as O (oxygen) is much lighter and its contribution is significantly lower. In this case, the proximity between the two elements in the projected image allows the obtained signal to be attributed to the combined Si and V. In Figure 1b, an experimental ADF micrograph is presented with the simulated one shown in the inset. This clearly indicates that it contains a pupil/channel (dark contrast) perpendicular to the plate surrounded by four chains about 18.5 Å long. Each chain contains 5 strong scatterers (indicated by red dots) separated by 3.7 Å. V atoms form -V-O-V- chains in a manner similar to the -Ti-O-Ti- chains observed in ETS-10 and ETS-4. By analyzing the intensity profile along the -V-O-V- chain, it can be observed that the central signal is more intense compared to the other four signals (Fig. 2). This is due to the presence of Si atomic columns that are much closer to the V columns (the projection), which results in higher atomic densities that cannot be separately analyzed due to their shorter distance, but all of them provide higher contrast. contribute to The simulated image based on the obtained crystallographic data is shown in the inset. The simulations were performed using QSTEM software to produce 20 nm supercells with microscopic parameters of 15 mrad convergence half-angle and 30 mrad ADF inner collection angle. The intensity profiles extracted from the experimental image (raw data) and the simulated one are very similar to each other, where 5 signals besides Si (5 maxima in the intensity profile) are identified due to the presence of 5 atomic V columns can be In both cases, the signal at the five centers is slightly higher compared to the others due to the closer to V of Si in the projection, demonstrating good agreement between the proposed model and the measured high-resolution images (Fig. 2). .

The measured Brunauer-Emmet Teller (BET) surface area of pure SGU-7 based on the _{N 2} adsorption isotherm at 77 K (Type I isotherm) ^{is 500 m 2} /g with a pupil volume ^{of 0.406 cm 3} g ^-1 , which is It is indicated that the material is a typical microporous material. The unit cell composition of the pure SGU-7 was determined to be _{Na 38} H ₂ Si ₈₀ V ₂₀ O _220· 55H _{2 O.} Thus, the pure SGU-7 contains ^{2H +} ions corresponding to 5% of the cation sites. Since Na ⁺ is the major cation in the pure sample at a percentage of 95%, the pure SGU-7 is hereafter denoted Na-SGU-7. The oxidation state of the V atoms in Na-SGU-7 is IV. This was determined by magnetic susceptibility, V 2p core-level X-ray photoelectron spectroscopy (XPS), and electron spin resonance (ESR) data.

^{Na +} and H ⁺ ions of Na-SGU-7 readily convert ^{Na +} and H ⁺ ions into divalent cations such as ^{Ca 2+} and Sr ²⁺ by aqueous ion exchange of the Na + and H + ions with the corresponding divalent cations (M ^{2+ ).} has been replaced The unit cell composition of SGU-7 exchanged with maximum Ca ²⁺ and Sr ²⁺ _{is, respectively, Ca 16.4} Na _7.2 Si ₈₀ V ₂₀ O _220· 74H ₂ O and Sr ₁₉ Na ₂ Si ₈₀ V ₂₀ O _220· 82H ₂ O to be. The M ²⁺ -exchanged SGU-7 samples are ^{denoted as M 2+} (x)-SGU-7, where M ²⁺ represents the major divalent cation and x in parentheses represents the degree of ion exchange as a percentage. Thus, the maximum Ca ²⁺ and Sr ²⁺ -exchanged SGU-7 samples are denoted as Ca(82)-SGU-7 and Sr(95)-SGU-7, respectively. Comparison of the maximum degree of ion exchange indicates that SGU-7 has the highest affinity for ^{Sr 2+} ions rather than ^{Ca 2+ .} In addition, the crystallinity of SGU-7 remained high after ion exchange, as shown in the synchrotron powder X-ray diffraction data (Fig. 1c).

High-resolution PXRD data of Na-SGU-7 (red) and Sr(95)-SGU-7 (black) (Fig. 1c) measured at the ID22 beamline at the European Synchrotron Radiation Facility (ESRF, France) indicates that they have high crystallinity (see Table 1 below).

[Table 1]

However, the unit cell could not be accurately determined and the crystal structure of SGU-7 could not be resolved from powder diffraction data due to severe preferred orientation, peak overlap and anisotropy. Therefore, the initial crystal structure models of Na-SGU-7, Ca(82)-SGU-7, and Sr(95)-SGU-7 were obtained from electron diffraction data obtained for several single sub-μm size crystals. became 3D EDT datasets were collected and processed using EDT-COLLECT and EDT-PROCESS software (Analitex), respectively. The inverse spatial coverage range was 105° to 115° when using an electron-beam-tilt step 0.15° for all samples. Laue class 2/m and the unit cell parameters were determined from a partially reconstructed 3D inverse space ( FIGS. 1D to 1F ). The determined unit cell parameters of Na-SGU-7 are a = 23.58 Å, b = 30.04 Å, c = 12.31 Å, β = 100.2° (see [Table 2] below).

[Table 2]

For Na-SGU-7, the reflection condition is summarized as {h 0 l : h =2n}, suggesting possible spatial groups P 1 a 1 , P 12/ a 1 and P 12 ₁ / a 1 . . The final spatial group of Na-SGU-7 was further confirmed to be P 12 ₁ / a using the additional reflection condition {0 k 0: k =2n} observed in the selected area electron diffraction (SAED) pattern. became The determined symmetry was used in the ab initio structure solution of Na-SGU-7 based on the reflection intensity extracted from the 3D EDT dataset.

The 3D EDT data recorded from Sr(95)-SGU-7 and Ca(82)-SGU-7 samples indicate that the symmetry of crystals gradually changes from P 12 ₁ / a 1 to C 12/ m 1 . (See Table 2 above and FIGS. 1E and 1F). From structural analysis of Na-SGU-7, Sr(60)-SGU-7, Sr(95)-SGU-7, and Ca(82)-SGU-7, the present inventors can conclude: ( 1) When Sr ²⁺ ion exchange degree or Ca ²⁺ ion exchange degree is less than 60%, Sr ²⁺ cation or Ca ²⁺ cation occupies an intra-layer position of Na-SGU-7 by displacing ^{Na + ion} . The symmetry does not change ( P 12 ₁ / a 1 ), but under the condition { hkl: h+k =2n}, the reflection intensity decreases significantly. (2) When the ^{degree of Sr 2+} ion exchange or Ca ²⁺ ion exchange rate reaches 80% to 95%, Sr ²⁺ or Ca ^{2+ becomes an interlayer Na +} ion occupying a higher symmetric interlayer Wyckoff position. start replacing them. This leads to a change in the space group to C 12/ m 1 . Replacing monovalent Na ⁺ cations with divalent cations (eg Sr ²⁺ and Ca ²⁺ ) requires doubling the amount of Na+ cations to maintain charge balance in the unit cell.

To further investigate the atomic structure of Na-SGU-7, high-resolution TEM images were obtained along different domain axes. The corresponding image is shown in FIG. 3 . The packing of the layer along the b axis can be observed in the images along the [100] and [001] orientations ( FIGS. 3A and 3C ), which is consistent with the identified structural model. Images according to the layer orientation are shown in FIGS. 3b and 3f. Bright contrasts of circles and small dots correspond to large and small pupils, respectively. The large pupils resemble 10-membered rings determined from their size. The identified structure of SGU-7 can be related to AM-14, vanadosilicate, and its X-ray powder diffraction pattern and crystal morphology are similar to those of SGU-7. However, structural details and specific properties of AM-14 have not been reported. In terms of the layered structure, SGU-7 can also be compared to KMS-1. However, ^{their behaviors are completely different in that the interlayer distance of KMS-1 increases when replacing 2K +} ions with Sr ²⁺ ions, while the interlayer distance of SGU-7 remains constant (Fig. 1c). Some minor phases were observed under STEM observation, the structure of which will not be discussed in detail herein.

Synchrotron PXRD patterns of Na-SGU-7 and Sr(95)-SGU-7 (Fig. 1c), and Ca(82)-SGU-7 can be indexed using unit cells and spatial groups determined from 3D EDT data and The finely analyzed unit cell parameters vary slightly for Ca(82)-SGU-7 and Sr(95)-SGU-7 samples. Atomic crystal structures were further precisely analyzed through Rietveld detailed analysis ( FIGS. 4b and 4d ). A large peak shape anisotropy exists (Fig. 5a and its inset), which is consistent with the crystal morphology observed by SEM images. Perhaps due to the strong dynamic scattering effect in electron diffraction, not all cations can be located in the ab initio structure solution. A differential Fourier map using synchrotron PXRD data clearly indicates the presence of ^{Na + cations in the vanadosilicate sheet. Additional Na +} ions and water molecules located between the zig-zag 10-ring channels and the vanadosilicate sheet were determined and analyzed precisely ( FIG. 5b ). In the case of Na-SGU-7, the crystal structure change occurs at 120° C., indicating that dehydration of the sample is not possible without interference with the structure. Thus, the ^{possible positions of the additional Na +} and water molecules were identified depending on compatible water-water and Na ^{+ -water distances.} Crosslinking between adjacent vanadosilicate sheets is ensured by Na-O interaction. In the case of Sr(95)-SGU-7, all Na ⁺ atoms ^{between the vanadosilicate sheets were replaced with Sr 2+} ( FIG. 5d ), which leads to the space group change observed in the EDT data.

The SGU-7 samples exhibit a well-defined layered structure with complete separation of the vanadosilicate sheet, which is stacked along the b- axis, resulting in Na-SGU-7 ( FIGS. 4a and 4b ) and Sr(95)-SGU- It provides a large interlayer space between them for water and cations as shown in case 7 ( FIGS. 4c and 4d ). In the case of Na-SGU-7 and Sr(95)-SGU-7, Na ⁺ and Sr ²⁺ ions connect adjacent vanadate sheets through their terminal oxygen atoms, respectively. The atomic arrangement determined within the layer is essentially the same for all three cases. Most surprisingly, the five vanadate ions in SGU-7 combine into a finite linear chain, which forms well-defined O-[VO ₄ -O] ₅ chains in each sheet ( FIGS. 6 and 7b ). _{This is -O-[VO 4} -O] _n - and - with infinite one-dimensional vanadate and titanate chains formed by an undefined infinite (n=∞) edge sharing of _{TiO 6} and VO ₆ octahedrons, respectively. O—[TiO ₄ —O] _n — is in contrast to the cases of AM-6 and ETS-10. These five V-atoms in the wire may correspond to the indicated scatterers (Fig. 1b). Therefore, SGU-7 offers a unique opportunity to study the physicochemical properties of oligomeric pentanuclear vanadate chains with well-defined chain lengths. The pentanuclear vanadate (V ₅ ) chains extend along the [101] orientation and _{are isolated from each other by [SiO 4} ] tetrahedra ( FIG. 7b ). As a result, zig-zag 10-ring channels are formed along the [010] orientation (Fig. 7c). The distinct layered structure of the SGU-7 is filled with channels extending perpendicular to the layers, breaking successive chains of _{-O-VO 4} -O-, separating them into _{V 5 chains.} The infinite -O-[VO ₄ -O] _n - chain (V _∞ ) of AM-6 exhibits a longitudinal oscillation peak at 871 cm ^{-1 in the Raman spectrum.} In SGU-7, the V ₅ chains exhibit a stronger and sharper Raman band at ^{889 cm −1} , which is higher than that of the V _∞ ^{wire by 18 cm −1} , which indicates that the length of _{V 5 is} It is due to the fact that it is shorter than that of V _∞.

3. Experimental method

(1) Sr ²⁺ capture

Sr ²⁺ - ²⁺ Sr by the _{scavenger-containing} collection of Sr ²⁺ from the solution was carried out as follows. To a 50 mL glass vessel were added 20 mL of Sr ²⁺ ₋ containing solution and 20 mg of adsorbent. The mixture was initially sonicated for 5 minutes and then stirred using a temperature-controlled water bath at 25° C. or the desired temperature for 12 hours or 24 hours. In most experiments, the volume to mass ratio ( V/m ) was 1 L/g or 1 L of solution per gram of ^{Sr 2+ -scavenger.} Only the liquid portion of the heterogeneous solution was isolated by centrifugation. ^{The concentration of Sr 2+} in the supernatant was determined by inductively coupled plasma-mass spectroscopy (ICP-MS). The amount of ^{radioactivity 226} Ra in solution was determined by measuring the alpha radiation emitted from the daughter nuclide ^{222 Rn.} The concentration of ^{radioactivity 137} Cs was measured using a gamma counter. Each data point represents the average of the three measured values.

(2) radioactive ⁹⁰ Sr ²⁺ capture

Radioactive waste solutions with initial activities of 28 Bq/mL and 32 Bq/mL (5.4 ppt and 6.2 ppt of ⁹⁰ Sr, respectively) were obtained from Eckert & Ziegler (Georgia, USA). The required amount of NaNO ₃ was added to the solution to obtain ⁹⁰ Sr ²⁺ -containing 2 M and 5 M Na ^{+ solutions.}

Trace of radioactive ⁹⁰ Sr ²⁺ was captured by adding 20 mg of Sr ²⁺ -scavenger to 20 mL of ⁹⁰ Sr ²⁺ -containing 2 M or 5 M Na ^{+ solution.} The mixture was sonicated at 25° C. for 24 h and stirred magnetically. The solution was centrifuged at 8,000 rpm and filtered. ^{The amount of 90} Sr ²⁺ in the supernatant was measured using Cerenkov radiation technique.

(3) radioactive ²²⁶ Ra ²⁺ capture

^{A radioactive 226} Ra ²⁺ solution with an initial activity of 43 Bq/mL (1.16 ppb) was prepared by dissolving ²²⁶ RaCl ₂ in water at a concentration of about 5x10 ^{-9 M. A 2 M Na +} solution was prepared by adding the required amount of NaCl to the solution. ^{After 226} Ra ²⁺ collection, the ^{concentration of radioactive 226} Ra ²⁺ in the supernatant was determined by ^{the 222} Rn emanation method using a liquid scintillation counter.

(4) pH-dependent Sr ²⁺ -Preparation of containing solutions

The initial Sr ²⁺ concentration adjusted to 1.02 ppm Sr ^{2+ Sr 2+} -containing solutions with different pH were prepared by adding the required amount of HCl or NaOH to the solution.

(5) Preparation of reaction mixture according to 1-equivalent conditions

In a typical experiment, 5 mg of SGU-7 powder and 1.027 L of a ^{solution containing 1.03 ppm of Sr 2+} were introduced into a 2 L glass flask. The mixture was sonicated for 5 minutes and the solution kept at room temperature with stirring for 12 hours. The volume to mass ratio of the solution was 205 L/g.

4. Analytical means

method. Computer-controlled Agilent (7700x series) inductively coupled plasma mass spectrometer (ICP) with octopole reaction system (ORS) with improved performance of helium (He) collision mode (detection limit of 0.2 ppt for Sr) -MS) was used to determine the concentrations of Sr ²⁺ , Ca ²⁺ , Mg ²⁺ , K ⁺ and Na ⁺ ions in the solution. Eight standard solutions ranging from 0 ppb to 1000 ppb were prepared by diluting standard solutions provided from Agilent. Standard samples were prepared in 5% nitric acid solution with ^{1 ppb 153} Eu internal standard to correct for instrumental drift and matrix effects during analysis. Na ⁺ highly concentrated solutions (2 M to 5 M Na ⁺ ions) were diluted to the ^{lower Na +} concentration by a factor of 10 or 20.

Characterization: Scanning Electron Microscopy (SEM) images were obtained using a field-emission scanning electron microscope JEOL JSM-7600 and Hitachi S-4300 operating at an accelerating voltage of 15 kV and 20 kV, respectively. Powder X-ray diffraction (XRD) patterns were obtained using a Rigaku D/MAX-2500/pc diffractometer. HRTEM images and selected area electron diffraction (SAED) patterns were collected on a JEM-2100F as well as a JEOL JEM-4010 microscope operating at 400 kV (Cs=0.8 mm, point resolution=1.5 Å) with LaB6 filaments. Energy dispersive X-ray spectroscopy (EDX) analysis was performed on a JEOL JEM-2100F. 3D using a high-tilt specimen holder on a JEOL JEM 2100F microscope operating at 200 kV (Cs = 0.8 mm, point resolution = 1.9 Å) with a Schottky-type field spinning gun, equipped with a Gatan US1000 CCD camera (2K x 2K). EDT data sets were collected. HRTEM images were simulated using the software Emap. The above structures were solved in a direct way using Sir 2014. _{High resolution spherical strain corrected (C s} -corrected) scanning transmission electron microscopy (STEM) was performed using a JEOL Grand ARM operating at 300 kV. The microscope is equipped with a cold field radiation gun and dual calibrators for the STEM and TEM modes to ensure point resolution in both cases of 0.7 Å. Before observation, the samples were deeply ground using a mortar and pestle and dispersed in absolute ethanol. A few drops of this suspension were placed on a holey carbon copper microgrid.

Multi-slice STEM simulation : To simulate the STEM-ADF data of the SGU-7 along the [010] direction, we used the QSTEM program. The crystalline supercell dimension used was 48.28Х103.22Х23.8 Å ³ , where 20 Å was used as the ideal thickness due to good agreement between the experimental and simulated data and information obtained from the SEM observations. The parameters used are: C _s = 0 mm, U _acc = 300 kV, internal collection angle 30 mrad and anti-convergence angle 15 mrad.

Zero-field cooled (ZFC) sensitivity measurement of SGU-7 samples from 4K to 300K in a magnetic field of 1000 G of a SQUID magnetometer (MPMS5) was performed at the Korea Basic Science Research Institute located at Korea University. Electron spin resonance (ESR) spectra were measured at room temperature on a Bruker A200 electron spin resonance spectrometer. ^{In a homemade setup equipped with an Ar +} ion laser (Spectra-Physics Stabilite 2017), a spectrometer (Horiba Jobin Yvon TRIAX 550), and a CCD detector (Horiba Jobin Yvon Symphony) as excitation beam source, cooled to 196°C. Raman spectra of the samples were recorded. The wavelength of the excitation beam was 514.5 nm. XPS data were measured using the ESCALAB250 XPS system from the Korea Basic Science Institute located in Busan. ^{Sr 2+} absorption and chemical composition were determined using ICP-MS (detection limit of 1 ppb), 7700 series, Agilent Technologies.

High-resolution powder diffraction data were recorded at the ID22 beamline at the European Synchrotron Radiation Facility (ESRF, France). Samples were packaged with 0.7 and 0.5 diameter borosilicate capillaries. The first series of diffraction patterns were collected at an energy of 31 keV (0.3999 Å) and used for the Pawley fit. In an attempt to remove some of the water molecules without inducing significant changes, a second series of diffraction patterns were collected after in situ pumping at an energy of 35 keV (0.3543 Å) and moderate heating (50° C. to 100° C.). The above patterns were used for Rietveld precise analysis of Na-SGU7 and Sr-SGU7. Pawley and Rietveld precision analyzes were performed using the TOPAS software package.

Calculation Details . Molecular dynamics (MD) simulations were performed at 298K. All calculations were performed by the BIOVIA Materials Studio 2016 package. We used a canonic (NVT) ensemble and a Nose thermostat with a Q ratio of 0.01. A very short time step of 1 fs was used to effectively integrate the equations of motion. After the initial 300 ps (3 x 10 ⁵ steps) equilibration, 10 ns (1 x 10 ⁷ steps) operation was performed with frame output every 2,500 steps. Therefore, a total of 4,000 constructs were used to obtain the average data. In addition, the present inventors performed three or more simulations on each model to obtain an average value. Na-SGU-7 (Na ₃₈ H ₂ Si ₈₀ V ₂₀ O ₂₂₀ 55H ₂ O, P 12 ₁ /a1, a = 23.58 Å, b = 30.04 Å, c = 12.31 Å, β = 100.2°) and Na-CST (Na ₈ Ti ₈ Si ₄ O ₂₈ ·8H ₂ O, P4 ₂ /mcm, a = b =7.8082 Å, c = 11.9735 Å, α = β = γ =90°) was used as the initial structural model. To obtain the Sr ²⁺ ion-exchange model, the present inventors made only one ^{Sr 2+} ion exchange model, mimicking the experimental conditions of ^{low Sr 2+ concentration (ppt) compared to extremely high Na +} ion concentration (ppm). . UFF (Universal Force Field) was used. The backbone charge was assigned using the charge balance method. The charges of O and H of Na, Sr, and H ₂ O were assigned +1, +2, -0.672 and +0.336, respectively. The summation of electrostatics ^{was performed by the Ewald method with an accuracy of 1.0 e −5} kcal/mol and the van der Waals interactions were cut using the cubic spline method with a 18.5 Å cutoff distance and long-range correction was applied.

5. Na ⁺ Sr of Na-SGU-7 from highly concentrated solution ²⁺ -Evaluation of capture ability

Initial evaluation of Na-SGU-7 for Sr ^{2+ removal included 35 ppb of Sr 2+} (as SrCl ₂ ) and 5.0 M Na ⁺ (115,000 ppm, as 4 M of NaNO ₃ ). This was performed using a simulated alkaline nuclear waste solution of pH = 14. The experiment was performed under 1 L/g condition by adding 20 mg of Sr ²⁺ -scavenger to 20 mL of the simulated waste solution. The applied 1 L / g condition often Sr ²⁺ - is used to evaluate the initial capacity of the scavenger - Sr ²⁺ from the contaminated solution. The performance of Na-SGU-7 was then compared to the performances of ^{12 other competing Sr 2+} -scavengers listed on the x-axis of FIG. 4A . The reason why 35 ppb was chosen as the concentration of ^{Sr 2+} is that it is close to or slightly above the upper limit of the concentration of ^{90 Sr in the reprocessed waste solution (26 ppb). The degree of Sr 2+} exchange by Na-SGU-7 was 99.1% after 12 hours and the corresponding partition coefficient ( K _d ) was 110,982 mL/g. Therefore, Na-SGU-7 showed the highest performance among the 13 samples tested (see Table 3 below).

[Table 3]

Simulated waste solution composition: Sr ²⁺ (35 ppb), Na ⁺ (115,000 ppm, or 5 M), pH = 14. Batch conditions 1 L/g, equilibration time 12 h at 25°C.

The ratio of the amount of solution 1 mL Sr ²⁺ remaining amount (Equation 1) of each removing Sr ²⁺ per 1 g of the removing agent, - the distribution coefficient K _d is Sr ²⁺

where [Sr ²⁺ ] _i and [Sr ²⁺ ] _f are the initial and final concentrations of Sr ²⁺ , V is the mL volume of the solution, and m is the weight of the ^{Sr 2+} -scavenger in g . Based on the above results, the present inventors, the two best samples, Na-SGU-7 and Na-CST, respectively, 46,000 ppm (2 M) and 115,000 ppm (5 M) of Na ⁺ were selected as two candidates to be tested for ppt level radioactive ^{90 Sr removal in the presence of Na + (see Table 3 above).}

The radioactivity of ⁹⁰ Sr in the tested 2 M Na ⁺ solution is 28,100 Bq/L, which ^{corresponds to 5.4 ppt or 6.0 x 10 -11} M (Fig. 8b). The results show that Na-SGU-7 can still remove 35.6% (20.82 picomole/Lg) of ^{90 Sr ions from the 2 M Na + solution, where the concentration of Na +} (2 M) is higher than ^{the concentration of 90 Sr.} 33 billion times higher. The calculated K _d of Na-SGU-7 was 536 mL/g. Under the same conditions, Na-CST is ^{7.5% of 90} Sr or 1,790 Bq/Lg can only be removed, which is 5.4 times lower than that of NaSU-7. _{The K d} of Na-CST is 69 mL/g, which is 7.8 times lower than that of Na-SGU-7 (536 mL/g).

^{The radioactivity of 90} Sr in the tested 5 M Na ⁺ solution is 32,100 Bq/L, which corresponds to ^{6.2 ppt or 6.8x10 -11 M.} Na-SGU-7 was still able to remove 10.9% (7.21 picomole/Lg) of the ^{90 Sr ions from the 5 M Na + solution ( FIG. 8c ), which was 90} despite the presence ^{of 115,000 ppm Na + ions.} Corresponding to 3,400 Bq/Lg of Sr, the concentration of ^{Na +} ions is 73 billion times higher than that ^{of 90 Sr.} The calculated K _d of Na-SGU-7 was 119 mL/g. The radioactivity removed by Na-CST under the same conditions was 4.4% (2.86 picomole/Lg) or 1,350 Bq/Lg, which was 2.5 times lower than that of Na-SGU-7. _{The K d} of Na-CST was 44 mL/g, which was 2.7 times lower than that of Na-SGU-7.

The results clearly indicate that Na-SGU-7 is the best material capable of removing ^{even ppt level radioactivity 90} Sr from the nuclear waste solution containing ^{5 M Na + .} To investigate the relative cation exchange energies of the two materials, we performed molecular dynamics simulations for Na-SGU-7 and Na-CST, and their Sr ^{2+ -exchange forms at 298 K.} In both cases, the ^{degree of Sr 2+ exchange is limited to one Sr 2+} ion (1 puc) per unit cell, so that the degree of ^{Sr 2+ ion exchange is very low while the concentration of Na+} is very high in the exchange conditions as close as possible to the actual exchange condition. made We found that the unit cell formula, symmetry, and parameters used for Na-CST are Na ₈ Ti ₈ Si ₄ O ₂₈ 8H ₂ O, P4 ₂ /mcm, and a=b=7.8082 Å, c=11.9735 Å , α=β=γ=90°. The Sr ²⁺ ion exchange process was expressed by Equation (2).

E ₁ E ₂ E ₃ E ₄

where [] _SrR and [] _Sol represent the concentrations of Sr-remover and the species in parentheses in solution, respectively. The ^{change in enthalpy of cation exchange reaction for Sr 2+} -scavenger (ΔE _R ) was obtained from equation (3).

ΔER = (E ₃ + E ₄ ) - (E ₁ + E ₂ ) (3)

The obtained ΔE _SGU-7 and ΔE _CST are -99.19 kcal/mol and -64.89 kcal/mol, respectively, indicating that Na-SGU-7 has a 1.5-fold higher thermodynamic affinity for ^{Sr 2+ than Na-CST.} indicates that it has

The above results explain why Na-SGU-7 is superior to Na-CST in Sr ^{2+ -removal in an extremely Na + rich solution.} This also indicates that the acquisition of thermodynamic stability is the driving force for the effective extraction of Sr ^{2+ under highly concentrated Na + conditions.} Consistent with this, according to a comparison of the in situ ^{powder X-ray diffraction patterns of the Na +} - and Sr ²⁺ -exchange forms of SGU-7 and CST obtained at various temperatures, the thermal stability of SGU-7 shows that Na ⁺ It shows an increase from 70°C to 180°C when replaced with ^{Sr 2+ .} However, the Sr ²⁺ -induced increase in thermal stability was not observed from CST. Rather, maximally Sr ^{2+ -exchanged} CST exhibits reduced thermal stability at temperatures above 225°C. Therefore, the present inventors concluded that the acquisition of structural stability acts as the main driving force for the particularly higher affinity for ^{Sr 2+} of SGU-7 than CST under ^{extremely high Na + conditions.}

6. Na ⁺ of Na-SGU-7 from highly concentrated solution. ²²⁶ Ra-capture ability evaluation

After obtaining information that SGU-7 has an excellent ability to trap ⁹⁰ Sr in highly concentrated Na ⁺ solutions, we conducted experiments to demonstrate ^{the 226 Ra-capturing ability of SGU-7, which is 226} Ra and ⁹⁰ Sr. Because they belong to the same group on the periodic table. In fact, ²²⁶ Ra is produced from ²³⁸ U, the most abundant (99.3%) isotope of U found in nature. ^{The half-life of 226} Ra is 1,622 years, which is converted to ²²² Rn, a carcinogenic gas that causes radioactive lung cancer. Therefore, effective capture of radioactive 226Ra from groundwater and radioactive liquid waste is very important for human health. ^{Therefore, we evaluated the 226} Ra-capturing ability of SGU-7 from a ^{2 M Na +} solution under neutral pH conditions. One of the reasons we chose the 2 M Na+ solution condition is to compare the results with those of Na-4-Mica, which has the highest ^{226 Ra-capturing ability.} Another reason is that if SGU-7 can ^{effectively capture 226} Ra in a ^{2 M Na +} solution, it can necessarily capture ^{226 Ra from groundwater. The initial radioactivity of the 226} Ra solution ( ^{as in the form of 226} RaCl ₂ ) was 43,000 Bq/L, which corresponds to 1.1 ppb as a chemical concentration. The 226Ra capture experiment was performed under the condition of 1 L/g using 20 mL of 226Ra solution and 20 mg of Na-SGU-7. The results show that, despite the fact that the concentration ^{of Na +} (2 M) ^{is 400 million times higher than that of 226} Ra ²⁺ , Na-SGU-7 contains 34.1% (1.71 nanomole/Lg) of ^{226 Ra ions from the 2 M Na + solution.} ) can be captured (Fig. 8d). Under the same conditions, Na-4-Mica only captured 5.5% (0.28 nanomole/Lg), which is 5.1 times lower than that of Na-SGU-7. The calculated K _d values of Na-SGU-7 and Na-4-Mica were 516 mL/g and 58 mL/g, respectively. Therefore, SGU-7 also has good ²²⁶ Ra trapping ability ^{in 2 M Na + solution.}

7. Sr of Na-SGU-7 from groundwater ²⁺ -Evaluation of capture ability

In the case of Sr ^2+, Sr ²⁺ present inventors of the Na-SGU-7 - is extended to evaluate the absorption into groundwater. To this end, an aqueous solution containing a neutral underground water of the simulated polluted with ^{Sr 2+ 42 ppb Sr 2+, 131.3} ppm Na +, 24.1 ppm Ca 2+, 10.1 ppm Mg 2+, and 7.3 ppm K ⁺ ions are used became Sr ²⁺ removal experiment was also performed under the condition of 1 L/g using 20 mL of groundwater and 20 mg of adsorbent. ^{The Sr 2+} -removing ability of Na-SGU-7 was compared with the Sr ²⁺ -removing ability of 12 other Sr ^{2+ -removing} agents (FIG. 9a and [Table 4]). Furthermore, Na-SGU-7 and the difference in Na-CST is small, but, Na-SGU-7 is Sr ²⁺ - was the highest performance in removing Sr ²⁺ from the contaminated ground water. These results show that Na-SGU-7 can also be used as ^{an Sr 2+} -scavenger for the effective removal of ^{90 Sr from unintentionally contaminated soil and groundwater.}

[Table 4]

Groundwater composition: Sr ²⁺ (0.042 ppm), Na ⁺ (131 ppm), Ca ²⁺ (24 ppm), Mg ²⁺ (10 ppm), K ⁺ (7 ppm). Batch conditions 1 L/g, equilibration time 12 h at 25°C.

^{While analyzing the disappearance of Sr 2+} from groundwater, the present inventors also analyzed changes in the concentration of the competing ions in groundwater. The present inventors confirmed that while 99.7% of Sr ²⁺ was eliminated from the simulated groundwater, 81.6% of Ca ²⁺ , 63.7% of Mg ²⁺ , and 8.5% of K ⁺ were also eliminated ( FIG. 9b ). On the other hand, although ^{the initial concentration of Na +} (131.3 ppm) was much higher than that of other metal ions, ^{the concentration of Na +} increased by 42% (55.1 ppm). Therefore, the present results show that Na ^{+ ions present in SGU-7 have Ca 2+} , Mg ²⁺ and even K even though the initial concentration of K ⁺ (7.3 ppm) is ^{much smaller than that of Na +} (131.3 ppm). ^Shows that it has been replaced with + . The above results show that the affinity of SGU-7 for metal ions increases in the order of ^{Na +} << K ⁺ < Mg ²⁺ < Ca ²⁺ < Sr ^{2+ .} This result also shows that when the valence charges of the metal ions are the same, SGU-7 has a higher affinity for divalent cations than monovalent cations, and softer (larger) cations compared to harder (smaller) cations. showed a higher affinity for Na-CST also showed a similar cation affinity profile. However, in the case of Na-CST, the ^{amount of ion exchange of Ca 2+} , Mg ²⁺ and K ⁺ to the host was higher than that to SGU-7. This phenomenon, although small, shows that Na-CST has a higher affinity for ^{Ca 2+} , Mg ²⁺ and K ^{+ than SGU-7.} This result explains why ^{SGU-7 exhibits superior Sr 2+} -capturing ability than Na-CST while capturing ^{Sr 2+ from groundwater.}

Sr ²⁺ removal rate of

The Sr ^{2+ -removal} rate is one of the important points to check while evaluating the performance of the ^{Sr 2+ -removal agent.} [Sr ²⁺ ] ^{More than 99% of Sr 2+} ions from the groundwater were removed within 5 minutes by SGU-7 under the 1 L/g condition of _{i = 1.03 ppm ( FIG. 9c ).} ^{This result indicates that the Sr 2+} removal rate by Na-SGU-7 from groundwater is very fast. Another important point to check is the Sr ²⁺ -removal capacity of the Sr-scavenger. This given amount of Sr ^2+-removing agent and Sr ²⁺ with respect to the solutions of a given volume-can be carried out by obtaining the best [Sr ^2+] _i to the remover to remove the Sr ²⁺ in an amount of 95% or more, and , because it provides very useful information about the amount of ^{Sr 2+} scavenger required to remove the ^{contaminated Sr 2+} from the solution. It was found that SGU-7 could remove 95.1% of Sr ^{2+ from groundwater at [Sr 2+} ] _i = 31.4 ppm under the condition of 1 L/g (Fig. 9d and [Table 5] below). The obtained K _d value was ^{higher than 10 4} mL/g ^{at [Sr 2+} ] _i = 31.4 ppm. These results indicate that SGU-7 has a very high ^{Sr 2+ removal capacity in groundwater.}

[Table 5]

Groundwater composition: Na ⁺ : 131 ppm, Ca ²⁺ : 24 ppm, Mg ²⁺ : 10 ppm, K ⁺ : 7 ppm. Batch conditions 1 L/g, equilibration time 12 h at 25°C.

Sr ²⁺ - Effect of temperature on capture capacity

Another important information for obtaining Sr ²⁺ -scavengers is the effect of temperature on ^{Sr 2+ -capturing capacity. The Sr 2+} -scavenger capacity of SGU-7 remained the same at >99% regardless of the temperature between 10 °C and 70 °C.

Sr under '1-equivalent' conditions and operable pH range ²⁺ degree of removal

Sr ²⁺ - Two other important point to make in order to assess the quality of the removing agent is Sr ²⁺ - operating remover is shown a very high performance, such as K _d> 10,000 mL / g (or log K _d> 4) available under a range of pH and "1 eq (one-equivalent)" conditions is about Sr ²⁺ Sr ²⁺ removed by a remover. Here, "one-equivalent" condition is the total number of Sr ²⁺ ions tested (target) concentration (a concentration of interest) in a total of Sr ²⁺ Sr ^2+, which resides in removing agent that resides in the solution - is equal to the number of replaceable site means that Thus, when [Sr ²⁺ ] _i is decreased, the total volume of the solution increases to hold 1 equivalent of Sr ²⁺ ions for ^{a given amount of Sr 2+ scavenger.} For example, for SGU-7, when [Sr ²⁺ ] _i = 1.03 ppm, based on its ion exchange sites, 205 L to give ^{the same number of Sr 2+ for 1 g of SGU-7} As much Sr ²⁺ solution is required. This also shows that when the routinely used 1 L/g condition was ^{applied to SGU-7 with [Sr 2+} ] _i = 1.03 ppm, only a very small fraction of the exchangeable site of SGU-7 was utilized. Nevertheless, the reason why the 1 L/g condition is widely used is that ⁹⁰ Sr is highly toxic even at very low concentrations, pushing the ^{ion exchange equilibrium towards the complete removal of Sr 2+ from the solution.} [Sr ²⁺ ] _i = 1.03 ppm under these '1-equivalent' conditions, the operable pH ^{of a Sr 2+} solution with a K _d >10 mL/g was 3-14. (FIG. 9e). This pH range is the same as that of KMS-1. However, the K _d of SGU-7 is 1,366,000 mL/g, whereas the K _d of KMS-1 is 25,000 mL/g, so at pH = 3.2, SGU-7 shows better performance than KMS-1 ( ] Reference). ^{Furthermore, Sr 2+} uptake by KMS-1 is greater than 55 mg/g in the pH range of 4-6, whereas Sr ²⁺ uptake by SGU-7 is greater than 105 mg/g in the pH range of 3-13. . This further demonstrates that SGU-7 is superior to KMS-1 in ^{Sr 2+ -removal ability. Interestingly, Sr 2+} uptake by SGU-7 at pH = 7 (109.0 mg/g) is small but slightly higher than under acidic or basic conditions (106.0 mg/g to 108.5 mg/g). This phenomenon appears to arise from the fact that there are extra cations such as ^{H +} under acidic conditions ^{and Na +} ions under basic conditions, ^{and these extra cations interfere with ion exchange of Sr 2+ to SGU-7.} At pH = 2, Sr ²⁺ uptake by SGU-7 was particularly very low (19.0 mg/g). This occurs because the structure of SGU-7 is stable in the pH range of 3 to 14 ( FIG. 10 ) but collapses at pH 2.6.

[Table 6]

Batch conditions 1 L/g, equilibration time 12 h at 25°C. * [MJ Monos, N. Ding and MG Kanatzidis, Proc. Natl. Acad. Sci. USA ., 2008, 105 , 3696-3699.].

Interestingly, the SGU-7 Sr ²⁺ - under removal capacity is much larger [Sr ^2+] _i = 1.03 ppm in 1 L / g condition than the amount of Sr ²⁺ ions in the ground water, pH is slightly increased from 3 to 14 In spite of this, the ^{degree of Sr 2+} -removal gradually increased ( FIG. 9f ). Most notably, in a 5M Na ⁺ solution, under the condition of 1 L/g with ^{[Sr 2+} ] _i ^{= 1.03 ppm, the degree of Sr 2+ -removal} from the solution sharply increased as the pH increased (Fig. 9g). . Thus, the Sr ²⁺ -removal was only 7.8% and 14.5% at pH 3 and 7, but 98.8% and 99.1% at pH 13 and 14, respectively. This is a highly desirable property for ^{Sr 2+ -scavengers} as it can be used to remove ^{radioactive 90} Sr ²⁺ directly from a pool of radioactive liquid waste solution having a pH of 14. Na-CST works similarly, but ^{with low Sr 2+} removal (Fig. 11).

8. Cs of SGU-7 ⁺ -Evaluation of capture ability

Although SGU-7 shows a high affinity for softer divalent cations such as ^{Sr 2+} and Ra ^{2+ , we also evaluated the Cs +} − trapping ability of SGU-7. The initial concentration of Cs ⁺ ([Cs ^+] _i) are respectively 8 ppb and 24 ppb of 1 L / g under ground water conditions, 77% and 75%, respectively, of Cs ⁺ is removed, respectively (Fig. 9h). The corresponding K _d values were 3,367 mL/g and 2,946 mL/g, respectively. [Cs ^+] _i is 24 ppb (2,946 mL / g) of SGU-7 of the K _d value of K of the two optimal material reported _d value of 17,500 mL / g (K-SGU -45) and 3,300 mL / g to 4,900 mL/g (CST), but still higher than the third optimal material, 2,300 mL/g (Na-PMica), which is 26 ppb of [Cs ⁺ ] _i under similar 1 L/g groundwater conditions. was measured. Although there are already significant amounts of two divalent cations, 24.1 ppm and 10.1 ppm respectively, Ca ²⁺ and Mg ^{2+ ,} and even higher amounts of the other monovalent cations, 131.3 ppm and 7.3 ppm respectively, Na ⁺ and K ⁺ . Despite this, the fact that SGU-7 can still ^{capture Cs+} from the groundwater is actually quite interesting. This again shows that SGU-7 has a much higher affinity for softer cations.

9. Reuse experiment of SGU-7

As a possible means for reusing SGU-7, the present inventors performed an experiment to remove ^{Sr 2+} ions from Sr(95)-SGU-7 ^{with Na + ions using a 5 M NaCl solution.} Even after washing 0.5 g of Sr(95)-SGU-7 4 times with 500 mL of 5 M NaCl solution for 2 hours, ^{2% of Sr 2+} still remains in SGU-7. This indicates that SGU-7 can be regenerated by ^{highly concentrated Na +} solution to remove ⁹⁰ Sr ²⁺ ions from ^{highly 90} Sr ^{2+ -contaminated solution.} However, as 42 ppb when the concentration of ⁹⁰ Sr ²⁺ is very low, and decreases gradually as the 1 L / g even removing ⁹⁰ Sr ²⁺ from the ground water increases the number of cycles under the following conditions, is used by using the high-concentration ion ⁺ Na Regeneration of Na-SGU-7 indicates that it is not effective to remove ⁹⁰ Sr ²⁺ from the solution contaminated with ^{very small amounts of 90} Sr ^{2+ .}

10. Conclusion

In summary, SGU-7 is a novel layered microporous vanadosilicate material with unit cell parameters a =23.58 Å, b =30.04 Å, c =12.31 Å, β =100.2˚ with spatial groups of P 12 ₁ / a 1 . . This material removes extremely biotoxic ppt-level traces of ⁹⁰ Sr ²⁺ from high pH (>13) extremely Na ^{+ rich (> 5 M) liquid waste produced during spent fuel rod reprocessing process.} It shows excellent ability to remove ^{most 90} Sr ²⁺ ions from accidentally contaminated groundwater ^{even with 90} Sr ²⁺ concentrations as high as 31 ppm. Acquisition of thermodynamic stability and increase in structural stability are driving forces for its excellent affinity for ⁹⁰ Sr ^{2+ and excellent selectivity for Sr 2+} with respect to ^{Na +} and other cations in groundwater and highly concentrated Na ⁺ (> 5 M) It gives the ability to effectively remove ^{Sr 2+} from liquid waste and incidentally contaminated groundwater. In addition, 1-ppb level of ²²⁶ Ra ²⁺ from 2 M NaCl solution and ppb level of Cs ⁺ from groundwater can be effectively captured. Its unique structure comprises a periodic network of isolated pentanuclear vanadate (V ₅ ) chains, whose optical and electrical properties can be exploited for various future applications.

The above description of the present application is for illustration, and those of ordinary skill in the art to which the present application pertains will understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present application. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and likewise components described as distributed may also be implemented in a combined form.

The scope of the present application is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims, and their equivalents should be construed as being included in the scope of the present application. .

Claims (20)

^{An Sr 2+} ion adsorbent comprising layered vanadosilicate, comprising:
The layered vanadosilicate has a microporous structure,
The layered vanadosilicate is represented by the following formula (1 ^{) comprising V ( IV)} , which is vanadium having an oxidation number of +4:
[Formula 1]

In Formula 1,
M is at least one selected from Na, Li, and K,
0≤a≤5;
1≤b; and
d=2 (b+c+10),
Sr ²⁺ ion adsorbent.
delete delete delete The method of claim 1,
wherein the layered vanadosilicate has a unit cell parameter of a =23.58 Å, b =30.04 Å, c =12.31 Å, β =100.2°, and a space group of P 12 ₁ / a ^{1 Sr 2+} ion adsorbent .
The method of claim 1,
^{The layered vanadosilicate containing V ( IV)} , which is vanadium having an oxidation number of +4 according to Chemical Formula 1, is reduced ^{to a vanadosilicate containing V ( V)} , which is vanadium having an oxidation number of +5 according to Chemical Formula 2 below. Which is obtained by, Sr ²⁺ ion adsorbent:
[Formula 2]

In Formula 2,
Wherein M is at least one selected from Na, Li, and K,
0≤a′≤5;
1≤b′; and
d′=2(b′+c′+10).
The method of claim 1,
wherein M ⁺ and/or H ⁺ are substituted by aqueous ion-exchange with the corresponding divalent cation, Sr ^{2+ , Sr 2+} ion adsorbent.
8. The method of claim 7,
The layered silicate is I bar Sr ²⁺ ion-exchange than Sr ²⁺ ion-in will be more stable after exchange, Sr ²⁺ ion adsorbent.
The method of claim 1,
The Sr ²⁺ ion to be adsorbed is a radioactive Sr, Sr ²⁺ ion adsorbent.
The method of claim 1,
The Sr ²⁺ ion adsorbent is in the form of a powder, foam, film, or a fixed bed column packed with the adsorbent, Sr ²⁺ ion adsorbent.
A method for removing ^{Sr 2+} ions from contaminated water to be removed ^{Sr 2+} ions containing 50 ppm or less of Sr ²⁺ ions and one or more other competing metal ions, the method comprising:
the total concentration of said one or more other competing metal ions is between 1 M and 8 M;
^{In order to remove Sr 2+} ions from the Sr ²⁺ ion removal target contaminated water ^{, the Sr 2+} ion adsorbent according to any one of claims 1 to 10 is used.
A method for removing ^{Sr 2+} ions, including.
12. The method of claim 11,
^{The concentration of Sr 2+} ions contained in the Sr ²⁺ ion removal target contaminated water is 30 ppm or less, the method of removing ^{Sr 2+ ions.}
12. The method of claim 11,
The total concentration of the one or more other competing metal ions included in the Sr ²⁺ ion removal target contaminated water is 2 M to 6 M, the method for removing ^{Sr 2+ ions.}
12. The method of claim 11,
The pH of the Sr ²⁺ ion removal target contaminated water is 3 to 14, the method for removing ^{Sr 2+ ions.}
12. The method of claim 11,
The competing metal ions are Na ⁺ , Ca ²⁺ , Mg ²⁺ , and K ⁺ will at least one selected from, Sr ²⁺ ion removal method.
12. The method of claim 11,
The layered vanadosilicate included in the Sr ^{2+ ion adsorbent is more stable after Sr 2+} ion-exchange than before Sr ²⁺ ion-exchange, Sr ²⁺ ion removal method.
^{Sr 2+} ion adsorbent according to any one of claims 1, 5 to 10, and
A container accommodating the Sr ²⁺ ion adsorbent but allowing ions to pass through
Containing, drinking water purification tea bag.
18. The method of claim 17,
The drinking water purification tea bag is for removing radioactive Sr in drinking water, drinking water purification tea bag.
^{11. A} method for treating polluted water for removing ^{Sr 2+} ions using the Sr 2+ ion adsorbent according to any one of claims 1 to 10.
20. The method of claim 19,
The polluted water is groundwater, seawater, or a nuclear waste solution, the polluted water treatment method.

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