KR20170022522A

KR20170022522A - Method for preparing titanosilicate using dropwise method and titanosilicate absorbent for removing radioactive nuclides prepared thereby

Info

Publication number: KR20170022522A
Application number: KR1020150117626A
Authority: KR
Inventors: 임우택; 최상준; 김영훈; 김후식; 이하영
Original assignee: 안동대학교 산학협력단
Priority date: 2015-08-21
Filing date: 2015-08-21
Publication date: 2017-03-02

Abstract

(B) preparing a second mixed solution by mixing sodium hydroxide and distilled water, (c) mixing the first mixed solution and the second mixed solution, and (c) mixing the first precursor and the silicon precursor, To a reaction vessel, stirring the mixture at a constant rate, and supplying the second mixture solution to the first mixture solution in a dropping manner to prepare a third mixture solution, and (d) heating the third mixture solution to crystallize And a step of preparing the titanosilicate by a drop method.
The method for producing titanosilicate using a drop method according to the present invention is characterized in that a mixed solution in which a titanium precursor and a silicon precursor are mixed is strongly stirred with a stirrer using a hydrothermal reactor having a large capacity Teflon container and a supply container capable of controlling a flow rate, At the same time, sodium hydroxide aqueous solution was uniformly supplied in a dropwise manner, uniformly mixed and stirred to maintain the reaction molar ratio constant without solidification of the reaction solution, thereby continuously maintaining the optimum conditions for the synthesis reaction. Thus, the titanosilicate It can be mass-produced efficiently.

Description

TECHNICAL FIELD The present invention relates to a titanosilicate-based adsorbent and a titanosilicate-based adsorbent. The titanosilicate-based adsorbent is a titanosilicate-

The present invention relates to a method for producing titanosilicate using a drop method and a titanosilicate-based adsorbent produced thereby.

Recently, the necessity of an efficient treatment technology of radioactive liquid wastes generated in case of a nuclear accident after the accident in Fukushima nuclear power plant in Japan has become an important issue. Conventionally, in order to treat such radioactive liquid wastes, liquid waste is evaporated, concentrated And the solidification process using paraffin as a solidifying agent is used to treat radioactive liquid waste.

However, the disposal method of radioactive liquid waste using the waste liquid evaporator is very effective for the concentration of waste, but it disadvantageously reduces the weight loss effect by concentrating all the solids without discriminating between the nuclides and non-nuclides, A large amount of operation cost is required due to the use of energy, and the efficiency of the evaporation process is significantly lowered due to scaling or entrainment in the evaporator due to organic matter.

In order to overcome the above-mentioned problems, various types of liquid radioactive treatment facilities such as an ion-exchange resin, a precise or ultrafiltration membrane, a reverse osmosis membrane, and the like have been recently operated for each nuclear reactor model.

However, the above-mentioned methods have limitations in handling a large amount of radioactive waste solution in the event of an emergency, and thus environmental degradation of the nuclear power plant is greatly reduced along with economic loss due to delays in power generation restart or significant environmental pollution. This is a desperate need.

Most of the radioactive nuclides of the liquid radioactive waste generated in the nuclear industry are Cs, Sr and I, and they are nuclides requiring long time-lapse and excessive shielding due to the emission of gamma rays. In particular, among the various radionuclides, Cs has a very high solubility, which is one of the elements requiring attention in the treatment of general nuclear waste. It has chemical properties similar to K, so it is readily absorbed by living organisms, Muscle, and the like, and is known to be highly involved in the genetic influence particularly on reproductive organs. Therefore, if Cs is selectively removed preferentially, subsequent waste treatment and radiation shielding management can be greatly facilitated.

Recently, research on the separation and removal of radioactive materials using various adsorbents and ion exchange resins has been carried out with the advantage of being capable of permanent treatment by adsorption or ion exchange treatment of radioactive liquid wastes, There is an increasing interest in adsorbents having a high selectivity to radioactive nuclides such as Cs and Sr.

Accordingly, it has been reported that the titanosilicate-based adsorbent is actively studied because it has high structural selectivity due to the high selectivity to Cs, and has excellent adsorption capacity and can be desorbed after use. It is progressing.

Titano silicate is a macroporous material having a pore size of 4 to 8 Å and is known to be synthesized by hydrothermal synthesis under alkaline conditions such as alumino, silicate and zeolite, and it is known that Ti, which is coordinated with the octahedron, , Zinc, arsenic, and mercury, and is known to be the most excellent material for removing radioactive nuclides Cs and Sr from the radioactive waste solution.

However, titanosilicates have a very limited crystallization region, and titanium is known to be difficult to synthesize because the reactants and final products are sensitive to pH.

For example, IE-911, a titanosilicate sorbent developed by UOP in the US, is known to have high selectivity for Cs and is used for the treatment of high-level waste water in the Handford Nuclear Power Plant in the United States.

In the case of studies on titanosilicate inorganic adsorbents in Korea, there is a disadvantage that it is difficult to synthesize materials having pure crystals because the synthesizable region is very narrow compared with other adsorbents. Therefore, the synthesis of other adsorbents (zeolite, etc.) The research is still insignificant, and the synthesis capacity remains at a size of 100 mL, and the yield in synthesis is also very small.

Therefore, various methods have been tried to mass-produce pure titanosilicate by applying a conventional method of sequentially synthesizing titanium reagent, silicate reagent, sodium hydroxide and distilled water. However, in the first place, the synthesis solution rapidly reacts to form a solid state, There is a phenomenon in which the material tends to adhere to the inner wall of the container, and there is a problem that the reaction of the reaction pressure and the temperature due to the increase in the capacity causes the synthesis of the other substance without crystallizing the titanosilicate. Research is confronting the limit.

Therefore, for the broad research and application of titanosilicate, research on a method for mass-synthesis of titanosilicate while maintaining excellent selectivity and adsorptivity to Cs is needed.

US Patent No. 6479427 (published on November 12, 2002) US Publication No. 2014/0190892 (published on July 10, 2014) Korean Patent Laid-Open No. 10-2012-0003319 (published on Jan. 10, 2012) Korean Patent Publication No. 10-2010-0110997 (published on October 14, 2010)

Disclosure of the Invention The present invention has been devised to solve the problems of the prior art as described above, and it is an object of the present invention to provide a method for producing titanosilicate capable of mass-synthesizing titanosilicate with high efficiency and maintaining excellent selectivity to cesium and adsorptivity .

According to an aspect of the present invention, there is provided a method for preparing a mixed solution, comprising: (a) mixing a titanium precursor and a silicon precursor to prepare a first mixed solution; (b) mixing sodium hydroxide and distilled water to prepare a second mixed solution; (C) supplying the first mixed solution to a reaction vessel, stirring the mixture at a constant rate, and supplying the second mixed solution in a dropping manner to the first mixed solution to prepare a third mixed solution; and and d) heating the third mixed solution to produce a crystallized titanosilicate. The present invention also provides a method of manufacturing a titanosilicate using a drop method.

The titanium precursor may be titanium isopropoxide (TTIP) or titanium tetrachloride.

The silicon precursor may include at least one selected from the group consisting of tetraethylorthosilicate (TEOS), fumed silica, and silica sol.

In addition, the reaction vessel is made of Teflon.

The third mixed solution is characterized by containing titanium: silicon: sodium: water in a reaction molar ratio of 1: 1.0 to 1.5: 5 to 10: 140 to 150.

The step (d) is performed at a temperature of 150 to 200 ° C for at least 48 hours.

The method may further include washing the titanosilicate crystallized in the step (d) and drying the titanosilicate.

The crystallized titanosilicate may be treated with distilled water, at least one selected from hydrochloric acid (HCl), nitric acid (HNO ₃ ), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ) and sodium hydroxide And then washed.

The present invention also provides a titanosilicate-based adsorbent for removing radionuclides comprising titanosilicate prepared by the above-described method.

The method for producing titanosilicate according to the present invention is characterized in that a mixed solution in which a titanium precursor and a silicon precursor are mixed is strongly stirred by a stirrer using a hydrothermal reactor having a large capacity Teflon vessel and a supply vessel capable of controlling a flow rate, By uniformly mixing and stirring a uniform amount of aqueous sodium hydroxide solution, the reaction molar ratio is kept constant without solidification of the reaction solution, thereby maintaining the optimal conditions for the synthesis reaction to efficiently mass-produce titanosilicate can do.

1 is a process diagram showing a method for producing titanosilicate according to the present invention.
Fig. 2 is an actual image of titanosilicate prepared according to Example 1. Fig.
FIG. 3 is a graph showing the results of X-ray diffraction analysis of titanosilicate prepared according to Examples 1 to 3, Comparative Example 1 and Comparative Example 2. FIG.
4 is a graph showing the results of analysis of cesium adsorption capacity of titanosilicate prepared according to Examples 1 to 3 and Comparative Example 1. Fig.
FIG. 5 is a graph showing the results of analysis of cesium adsorption ability at a high salt concentration of titanosilicate prepared according to Examples 1 to 3 and Comparative Example 1. FIG.

Hereinafter, the present invention will be described in detail.

The present invention relates to a process for preparing and mixing a mixed solution containing titanium and silicon and an aqueous solution of sodium hydroxide, wherein the reaction mixture is uniformly mixed at a constant molar ratio at the time of mixing to produce a reaction solution in which a constant reaction molar ratio is maintained, And more particularly, to a high-yield titanosilicate production method capable of mass-producing pure titanosilicate by heating the reaction solution.

FIG. 1 is a process diagram showing a method for producing titanosilicate using a drop method according to the present invention.

As shown in FIG. 1, the method for preparing titanosilicate using a drop method according to the present invention comprises the steps of (a) mixing a titanium precursor and a silicon precursor to prepare a first mixed solution, (b) mixing sodium hydroxide and distilled water (C) feeding the first mixed solution into a reaction vessel and stirring the mixture at a constant speed, and supplying the second mixed solution into the first mixed solution in a dropping manner to form a third mixed solution, And (d) heating the third mixed solution to prepare a crystallized titanosilicate.

The step (a) may be a step of preparing a precursor for producing titanosilicate. The titanium precursor and the silicon precursor may be mixed to prepare a first mixed solution. The titanium precursor and the silicon precursor may be mixed as described below And the skeleton of the titanosilicate crystal having the octahedron and the tetrahedron at the same time.

The first mixed solution may be configured to include a titanium precursor and a silicon precursor in a ratio of 1: 1 to 1: 4 to prepare titanosilicate in a step to be described later.

When the proportion of the titanium precursor is less than 1 or more than 4, the titanium content of the titanosilicate to be produced is not sufficient and the purity of the titanosilicate may be lowered or the adsorption capacity may be lowered. And the like.

At this time, titanium isopropoxide (TTIP) or titanium tetrachloride (TiCl ₄ ) alone or a mixture thereof may be used as the titanium precursor.

The silicon precursor may be configured to use a tetraethylorthosilicate (TEOS), a fumed silica, a silica sol, or a mixture thereof to form a titanosilicate skeleton. have.

In the step (b), the second mixed solution may be prepared by completely dissolving sodium hydroxide in distilled water.

When the second mixed solution is added to the first mixed solution, the sodium ion contained in the second mixed solution acts as a structure stabilizing ion, thereby stabilizing the titanosilicate crystals prepared in the step described later.

In the step (c), the third mixed solution is prepared by mixing the second mixed solution prepared as described above into the first mixed solution.

In the method for producing titanosilicate according to the present invention, a first mixed solution and a second mixed solution are prepared and mixed for the production of titanosilicate, and they are uniformly mixed at a constant molar ratio at the time of mixing so that a constant reaction molar ratio is maintained To produce a third mixed solution.

For reference, when the second mixed solution is excessively added in the production of the third mixed solution, the solidification phenomenon occurs in which the titanium and silicon contained in the first mixed solution abruptly react with sodium hydroxide to aggregate the third mixed solution. It is difficult to prepare the dispersed third mixed solution. If a small amount of the second mixed solution is added, the synthesis time of the titanosilicate may increase or the synthesis of the titanosilicate may not proceed smoothly .

Therefore, a uniform amount of the second mixed solution can be supplied to the first mixed solution at an appropriate rate by using the drop method, and the third mixed solution can be configured to be continuously stirred to produce a sufficiently dispersed third mixed solution.

For this purpose, in this step, a hydrothermal reactor having a large capacity container and a container capable of controlling the flow rate are used, and the first mixed solution is supplied to the hydrothermal reactor, and then stirred with a stirrer, And a third mixing solution in which the reaction molar ratio is kept constant without solidification phenomenon in which the reaction solution is solidified is constructed. In the following step, in the synthesis of the titanosilicate, Can be continuously maintained in order to efficiently mass-produce pure titanosilicate.

At this time, the above-mentioned large-capacity reaction vessel can be configured to use various known well-known vessels which are not reactive. For example, it is preferable to use a vessel made of Teflon.

Also, the third mixed solution may be composed of titanium: silicon: sodium: water in a reaction molar ratio of 1: 1.0 to 1.5: 5 to 10: 140 to 150 so that the selectivity and adsorptivity to cesium Can be configured to mass produce excellent pure titanosilicates.

In the step (d), the third mixed solution is heated to induce a crystallization reaction to produce a titanosilicate crystal. The third mixed solution is heated to induce hydrothermal synthesis to form a crystallized titanosilicate .

In this step, the hydrothermal synthesis is preferably carried out at a temperature of 100 to 300 ° C for 24 to 150 hours, more preferably at a temperature of 150 to 200 ° C for at least 48 hours, To form a titanosilicate crystal.

In this step, the titanosilicate crystals having improved selectivity are prepared by additionally washing the titanosilicate crystals prepared in this step. Distilled water, hydrochloric acid (HCl), nitric acid (HNO ₃ ), sulfuric acid (H ₂ SO ₄ ) , Phosphoric acid (H ₃ PO ₄ ), sodium hydroxide (NaOH), or the like.

For example, the titanosilicate can be prepared by cooling the titanosilicate to room temperature, washing with distilled water, and washing with 1 M hydrochloric acid and 1 M sodium hydroxide, respectively.

The method may further include drying the washed titanosilicate crystals. The drying may be performed using various known drying methods, and preferably at a temperature of 50 ° C.

The method of manufacturing the titanosilicate using the drop method according to the present invention as described above is characterized in that a mixed solution in which a titanium precursor and a silicon precursor are mixed using a hydrothermal reactor having a large capacity of Teflon container and a supply container capable of controlling the flow rate, The reaction solution is uniformly mixed and stirred to uniformly supply an aqueous solution of sodium hydroxide in a uniform amount in a dropping manner while maintaining a constant molar ratio of the reaction solution without solidification phenomenon, The titanosilicate can be efficiently mass produced.

The present invention also provides a titanosilicate-based adsorbent for removing radioactive nuclides containing titanosilicate prepared by the above-described method, wherein the titanosilicate having a strong selectivity and adsorptivity to cesium is dissolved in fresh water or seawater It can be effectively used as an adsorbent for removing radionuclides capable of treating the contained radioactive material.

Hereinafter, the present invention will be described in more detail with reference to examples. The embodiments presented are only a concrete example of the present invention and are not intended to limit the scope of the present invention.

&Lt; Example 1 >

Titanium silicate was prepared under the conditions shown in Table 1 below. To this end, a hydrothermal synthesizer having a 10 L capacity Teflon vessel was charged with 650 g of titanium isopropoxide (TTIP) and 480 g of tetraethylorthosilicate TEOS) was added and stirred for a sufficient time with a stirrer.

750 L of sodium hydroxide was added to 7 L of distilled water to completely dissolve it, and an aqueous solution of sodium hydroxide was supplied to a large-capacity column equipped with a coke, followed by placing it on the hydrothermal synthesizer.

The coke was opened and sodium hydroxide aqueous solution was continuously supplied to the vessel containing TTIP and TEOS at a constant time interval and stirred vigorously for 1 hour after the supply of the sodium hydroxide solution was completed.

The hydrothermal synthesizer having a mixed solution of TTIP, TEOS and sodium hydroxide was heated in an electric furnace at a temperature of 170 ± 5 ° C for 96 hours to prepare titanosilicate. The titanosilicate thus prepared was dissolved in ethanol and distilled water Washed and dried in an oven at 50 ° C to obtain titanosilicate. The obtained titanosilicate was photographed and shown in FIG.

[Table 1]

As shown in FIG. 2, it was confirmed that the obtained titanosilicate was well synthesized in the form of fine powder.

Further, in order to analyze the synthesis of the titanosilicate, the titanosilicate according to Example 1 was subjected to X-ray diffraction analysis, and the results of the analysis are shown in FIG.

As shown in FIG. 3, it was confirmed that the characteristic diffraction pattern of the titanosilicate was clearly observed under the conditions of Example 1, and it was confirmed that the titanosilicate can be effectively prepared using the drop method.

&Lt; Example 2 >

The titanosilicate was prepared under the conditions shown in Table 1. For this purpose, a hydrothermal synthesizer having a 1 L capacity Teflon vessel was charged with 65 g of titanium isopropoxide (TTIP) and 48 g of tetraethylorthosilicate TEOS) was used, and 75 g of sodium hydroxide was added to 700 mL of distilled water to prepare titanosilicate.

In order to analyze the synthesis of the titanosilicate, the titanosilicate according to Example 2 was subjected to X-ray diffraction analysis, and the results of the analysis are shown in FIG.

As shown in FIG. 3, it was confirmed that the characteristic diffraction pattern of the titanosilicate was apparent under the conditions of Example 2, and it was confirmed that the titanosilicate can be effectively produced by using the drop method.

&Lt; Example 3 >

To this end, titanosilicate was prepared under the conditions shown in Table 1. To this, 32.5 g of titanium isopropoxide (TTIP) and 24 g of tetraethylorthosilicate (manufactured by Tosoh Corporation) were added to a hydrothermal synthesizer having a 1 L capacity Teflon vessel TEOS) was used, and 37.5 g of sodium hydroxide was added to 350 mL of distilled water to prepare titanosilicate.

To analyze the synthesis of titanosilicate, the titanosilicate according to Example 3 was subjected to X-ray diffraction analysis, and the results of the analysis are shown in FIG.

As shown in FIG. 3, it was confirmed that the characteristic diffraction pattern of the titanosilicate was apparent under the conditions of Example 3, and it was confirmed that the titanosilicate can be effectively produced by using the drop method.

&Lt; Comparative Example 1 &

Titanium silicate was prepared under the conditions shown in Table 1. To this, 6.5 g of titanium isopropoxide (TTIP) and 4.8 g of tetraethyl orthosilicate (manufactured by Tosoh Corporation) were added to a hydrothermal synthesizer equipped with a 100 mL capacity Teflon vessel TEOS) and 70 g of sodium hydroxide dissolved therein was prepared. The hydrothermal synthesizer having the mixed solution thus prepared was heated in an electric furnace at a temperature of 170 ± 5 ° C for 84 hours to prepare titanosilicate The prepared titanosilicate was washed with ethanol and distilled water using a vacuum filtration apparatus, and then dried in an oven at 50 ° C. to obtain titanosilicate.

In order to analyze the synthesis of titanosilicate, the titanosilicate according to Comparative Example 1 was subjected to X-ray diffraction analysis, and the results of the analysis are shown in FIG.

As shown in FIG. 3, it was confirmed that the characteristic diffraction pattern of the titanosilicate was apparent under the conditions of Comparative Example 1, and it was confirmed that the titanosilicate was produced.

&Lt; Comparative Example 2 &

To this end, a titanosilicate was prepared under the conditions shown in Table 1. To this, 32.5 g of titanium isopropoxide (TTIP), 24 g of tetraethylorthosilicate TEOS) and 350.5 mL of an aqueous solution of sodium hydroxide dissolved in 32.5 g was prepared. The hydrothermal synthesizer having the mixed solution thus prepared was heated in an electric furnace at a temperature of 170 ± 5 ° C for 96 hours to prepare titanosilicate The prepared titanosilicate was washed with ethanol and distilled water using a vacuum filtration apparatus, and then dried in an oven at 50 ° C. to obtain titanosilicate.

In order to analyze the synthesis of titanosilicate, the titanosilicate according to Comparative Example 2 was subjected to X-ray diffraction analysis, and the results of the analysis are shown in FIG.

As shown in Fig. 3, in the condition of Comparative Example 2, characteristic diffraction pattern of titanosilicate does not appear as in Comparative Example 1, and it can be confirmed that titanosilicate is not produced.

<Experimental Example 1> Analysis of the yield of titanosilicate according to the production capacity

The yield of titanosilicate according to Examples 1 to 3 and Comparative Example 1 was measured in order to analyze the yield of titanosilicate with increasing production capacity. The measurement results are shown in Table 2 below.

[Table 2]

As shown in Table 2, it was confirmed that the yield was 25 g in the condition of Example 1, 48 g in the condition of Example 2, and 470 g in the condition of Example 3.

On the other hand, in the conditions of Comparative Example 1, the yield of the titanosilicate was very small as 4 g, and when the method of producing the titanosilicate according to the present invention was used, it was confirmed that the titanosilicate could be mass- I could.

<Experimental Example 2> Cesium removal efficiency of the produced titanosilicate

To analyze the cesium removal efficiency of the produced titanosilicate, 0.1 g of titanosilicate according to Examples 1 to 3 and Comparative Example 1 was added to 15 mL of a solution having a cesium concentration of 100 ppm, and the mixture was stirred for 24 hours, The supernatant was sampled, the impurities were removed by a filter, and the content of cesium remaining in the solution was measured using an inductively coupled plasma spectrometer. The results are shown in Table 3 and FIG.

[Table 3]

As shown in Table 3 and FIG. 4, the removal efficiency of cesium ions of the titanosilicate according to Example 1 which was mass-produced using the drop method was 94.6%, 94.4% in the case of the titanosilicate according to Example 2, The titanosilicate content was 93.9%, which is similar to that of Comparative Example 1, so that even when a large amount of titanosilicate was prepared using the drop method, the cesium removal rate was similar to that of the dropwise method, And it can be effectively used for eliminating nuclides.

<Experimental Example 3>: Analysis of cesium removal efficiency at a high salt concentration of the produced titanosilicate

In order to analyze the cesium removal efficiency at the high salt concentration of the prepared titanosilicate, the aqueous solutions having the cesium concentration of 300 ppm and the sodium chloride concentrations of 118 ppm, 1180 ppm and 11800 ppm, respectively, were added to Examples 1 to 3 and Comparative Example 1 And the mixture was stirred for 24 hours. Then, the supernatant was collected, the impurities were removed by a filter, and the content of cesium remaining in the solution was measured using an inductively coupled plasma spectrometer. The measurement results are shown in Tables 4 and 5, 5.

[Table 4]

As shown in Table 4 and FIG. 5, the cesium ion removing ability of the titanosilicate according to Examples 1 to 3, which were mass-produced by using the drop method, was similar to Comparative Example 1 regardless of the increase in the concentration of sodium chloride in the solution And it can be confirmed that titanosilicate prepared by mass-production of titanosilicate using drop method can be effectively used for removing radioactive cesium contained in seawater.

Through the above experimental results, it was confirmed that the titanosilicate can be mass-produced through the drop method of the present invention. Since the purity and cesium ion removal performance are as good as those of pure titanosilicate, It is confirmed that this is a remarkable manufacturing method in mass production and application of silicate.

Claims

(a) preparing a first mixed solution by mixing a titanium precursor and a silicon precursor;
(b) mixing sodium hydroxide and distilled water to prepare a second mixed solution;
(c) supplying the first mixed solution to a reaction vessel, stirring the mixed solution at a constant rate, and supplying the second mixed solution in a dropping manner to the first mixed solution to prepare a third mixed solution; And
(d) heating the third mixed solution to produce a crystallized titanosilicate.

The method according to claim 1,
Wherein the titanium precursor is titanium isopropoxide (TTIP) or titanium tetrachloride. &Lt; RTI ID = 0.0 > 15. < / RTI >

The method according to claim 1,
Wherein the silicon precursor comprises at least one selected from the group consisting of tetraethyl orthosilicate (TEOS), dry silica (Fumed silica), and silica sol (Silica sol).

The method according to claim 1,
Wherein the reaction vessel is made of Teflon.

The method according to claim 1,
Wherein the third mixed solution comprises titanium: silicon: sodium: water in a reaction molar ratio of 1: 1.0 to 1.5: 5 to 10: 140: 150.

The method according to claim 1,
Wherein the step (d) is performed at a temperature of 150 to 200 DEG C for 48 hours or more.

The method according to claim 1,
And washing the titanosilicate crystallized in the step (d) and drying the titanosilicate.

8. The method of claim 7,
The crystallized titanosilicate is washed using distilled water, at least one selected from hydrochloric acid (HCl), nitric acid (HNO ₃ ), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ) and sodium hydroxide Wherein the titanosilicate is produced by a method comprising the steps of:

A titanosilicate-based adsorbent for removing radioactive nuclides comprising a titanosilicate prepared by the method according to any one of claims 1 to 8.