Preparation and application of hexamethylenetetramine modified mercuric sulfide silica gel

Abstract

The invention discloses a hexamethylenetetramine modified mercuric sulfide silica gel preparation method, which comprises: 1, placing silica gel in a dilute nitric acid solution, and carrying out activation treatment to obtain activated silica gel; 2, adding the activated silica gel into a mercuric nitrate solution, carrying out dipping treatment, and drying to obtain mercuric salt modified silica gel; step 3, adding the mercury salt modified silica gel obtained in the step 2 into an L-cysteine solution, carrying out dipping treatment, and then carrying out hydrothermal reaction, filtering, washing and drying to obtain mercuric sulfide silica gel; and 4, adding the mercuric sulfide silica gel obtained in the step 3 into a hexamethylenetetramine solution, carrying out dipping treatment, and drying to obtain the hexamethylenetetramine modified mercuric sulfide silica gel. The hexamethylenetetramine modified mercuric sulfide silica gel can simultaneously trap elemental iodine and methyl iodide, has high adsorption capacity for elemental iodine and methyl iodide, and is simple in preparation method and convenient for large-scale application.

Description

Technical Field

[0001] The present invention belongs to the technical field of iodine adsorption materials. More specifically, the present invention relates to the preparation and application of hexamethylenetetramine-modified mercury sulfide silica gel. Background Art

[0002] Nuclear energy, as a new energy source, has been continuously developed and utilized. Although the nuclear power supply in China accounts for 5% of the total electricity, the radioactive waste generated by nuclear power is huge. Effectively and safely managing the radioactive waste generated at each stage of the nuclear fuel cycle is a challenge in the process of nuclear energy utilization, and this is also the main reason restricting the development of nuclear energy. However, during the process of recovering key elements from spent fuel reprocessing, a large amount of radioactive gas will inevitably be released due to acid leaching. Radioactive iodine ( 129 I and 131 I) gas is one of these released gases and has extremely strong radioactivity and biological toxicity. The effective capture of radioactive iodine has become an important research direction in the field of spent fuel reprocessing. There is a specially designed iodine filter device in the tail gas treatment process of the reprocessing plant, and its stable operation and efficient purification are important guarantees for ensuring the compliance of tail gas emissions. The tail gas enters the iodine filter after being heated to above 130 °C. In the iodine filter, when the gas passes through the filter layer filled with silver-loaded silica gel adsorbent, most of the iodine (mainly 129 I) is adsorbed by the silver-loaded silica gel. The silver-loaded silica gel iodine adsorbent used in the reprocessing plant still adopts the scientific research achievements of the 1980s. Although it can generally meet the operation requirements of the reprocessing plant, there are problems such as small iodine adsorption capacity and high cost during use. Therefore, it is necessary to develop a new type of efficient and economical adsorption material to replace the traditional silver-based material, which has important practical significance for the effective capture of radioactive iodine vapor, improving the spent fuel reprocessing technology level in China, and promoting the sustainable development of nuclear energy. Summary of the Invention

[0003] An object of the present invention is to solve at least the above problems and / or defects and provide at least the advantages described hereinafter.

[0004] To achieve these objects and other advantages of the present invention, a preparation method of hexamethylenetetramine-modified mercury sulfide silica gel is provided, including the following steps:

[0005] Step 1: Place silica gel in a dilute nitric acid solution for activation treatment to obtain activated silica gel;

[0006] Step 2: Add the activated silica gel to a mercury nitrate solution for impregnation treatment, and then dry to obtain mercury salt-modified silica gel;

[0007] Step 3: Add the mercury salt-modified silica gel obtained in Step 2 into the L-cysteine solution, perform impregnation treatment, then carry out hydrothermal reaction, filter, wash, and dry to obtain mercury sulfide silica gel.

[0008] Step 4: Add the mercury sulfide silica gel obtained in Step 3 into the hexamethylenetetramine solution, perform impregnation treatment, and dry to obtain hexamethylenetetramine-modified mercury sulfide silica gel.

[0009] Preferably, in Step 1, the concentration of the dilute nitric acid solution is 3-5 wt%; the silica gel is water-resistant silica gel; the mass-volume ratio of the silica gel to the dilute nitric acid solution is 1 g: 3-5 mL.

[0010] Preferably, in Step 1, the specific method of the activation treatment is: stir at 90-110 °C for 3-5 h, filter, wash 1-5 times successively with deionized water and absolute ethanol, and then dry in an air atmosphere at 110-150 °C for 20-28 h.

[0011] Preferably, in Step 2, the preparation method of the mercury nitrate solution is: add concentrated nitric acid with a concentration of 65-68 wt% into deionized water to prepare a dilute nitric acid solution, and then dissolve mercuric nitrate hydrate in the dilute nitric acid solution to obtain a mercury nitrate solution; wherein, the volume ratio of the concentrated nitric acid to the deionized water is 1: 8-10; the mass-volume ratio of the mercuric nitrate hydrate to the dilute nitric acid solution is 0.25-0.35 g: 1 mL.

[0012] Preferably, in Step 2, the mass-volume ratio of the activated silica gel to the mercury nitrate solution is 0.5-1.0 g: 1 mL; the impregnation treatment is: impregnate at room temperature for 20-28 h; the drying is: dry in an air atmosphere at 110-150 °C for 20-28 h.

[0013] Preferably, in Step 3, the preparation method of the L-cysteine solution is: add L-cysteine into ethylene glycol to obtain an L-cysteine solution with a concentration of 45-55 g / L.

[0014] Preferably, in Step 3, the impregnation treatment is: impregnate at room temperature for 0.5-2 h; the hydrothermal reaction is: react in a polytetrafluoroethylene container in an air atmosphere at 170-190 °C for 20-28 h; the washing is: wash 1-5 times successively with deionized water and absolute ethanol; the drying is: dry in an air atmosphere at 180-220 °C for 20-28 h; the volume-mass ratio of the L-cysteine solution to the activated silica gel in Step 2 is 5-10 mL: 1 g.

[0015] Preferably, in Step 4, the preparation method of the hexamethylenetetramine solution is: dissolve hexamethylenetetramine in deionized water to obtain a hexamethylenetetramine solution with a concentration of 150-250 g / L.

[0016] Preferably, in the fourth step, the impregnation treatment is: impregnating for 20 - 28 h at room temperature; the drying is: drying for 20 - 28 h in an air atmosphere at 80 - 120 °C; the volume - mass ratio of the hexamethylenetetramine solution to the activated silica gel in the second step is 1 - 2 mL:1 g.

[0017] Application of the hexamethylenetetramine - modified mercury sulfide silica gel prepared by the preparation method as described above in capturing radioactive gaseous iodine.

[0018] The present invention has at least the following beneficial effects: The hexamethylenetetramine - modified mercury sulfide silica gel of the present invention can capture both elemental iodine and methyl iodide, has a high adsorption capacity for elemental iodine and methyl iodide, and at the same time, the preparation method of the present invention is simple and convenient for large - scale application.

[0019] Other advantages, objectives, and features of the present invention will be partially reflected by the following description, and partially will be understood by those skilled in the art through the research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 XRD patterns of the activated silica gel prepared in Comparative Example 1, the mercury sulfide silica gel prepared in Comparative Example 3, and the hexamethylenetetramine - modified mercury sulfide silica gel prepared in Example 1 of the present invention;

[0021] Figure 2 FT - IR patterns of the activated silica gel prepared in Comparative Example 1, the mercury sulfide silica gel prepared in Comparative Example 3, and the hexamethylenetetramine - modified mercury sulfide silica gel prepared in Example 1 of the present invention;

[0022] Figure 3 SEM patterns of the activated silica gel (a, b) prepared in Comparative Example 1, the mercury sulfide silica gel (c, d) prepared in Comparative Example 3, and the hexamethylenetetramine - modified mercury sulfide silica gel (e, f) prepared in Example 1 of the present invention;

[0023] Figure 4 TGA patterns of the activated silica gel prepared in Comparative Example 1, the mercury sulfide silica gel prepared in Comparative Example 3, and the hexamethylenetetramine - modified mercury sulfide silica gel prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] The following further describes the present invention in detail with reference to the drawings, so that those skilled in the art can implement it according to the description in the specification.

[0025] It should be understood that the terms such as "having", "comprising", and "including" used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0026] Example 1

[0027] A preparation method of hexamethylenetetramine-modified mercuric sulfide silica gel, comprising the following steps:

[0028] Step 1: Place 300 g of water-resistant silica gel into 945 mL of a dilute nitric acid solution with a mass concentration of 3 wt%, stir in a constant-temperature oil bath at 100 °C for 4 h, filter with a sieve, wash 3 times with deionized water and absolute ethanol, then put it into a blast drying oven and dry in an air atmosphere at 130 °C for 24 h to obtain activated silica gel;

[0029] Step 2: Add 1.5 mL of 68 wt% concentrated nitric acid to 12.5 mL of deionized water to prepare a dilute nitric acid solution. Dissolve 4.2699 g of mercuric nitrate hydrate in 14 mL of the dilute nitric acid solution to obtain a mercuric nitrate solution. Weigh 10 g of activated silica gel and add it to the mercuric nitrate solution, impregnate at room temperature for 24 h, then put it into a blast drying oven and dry in an air atmosphere at 130 °C for 24 h to obtain mercuric salt-modified silica gel;

[0030] Step 3: Add 3.6235 g of L-cysteine to 70 mL of ethylene glycol to obtain an L-cysteine solution. Add the mercuric salt-modified silica gel obtained in Step 2 to the L-cysteine solution, impregnate at room temperature for 1 h, then transfer it to a 100 mL polytetrafluoroethylene bottle, place it in a reaction kettle, carry out a hydrothermal reaction in an air atmosphere at 180 °C for 24 h, filter and wash 3 times with deionized water and absolute ethanol, put it into a blast drying oven and dry in an air atmosphere at 200 °C for 24 h to obtain mercuric sulfide silica gel;

[0031] Step 4: Dissolve 2.5 g of hexamethylenetetramine in 13 mL of deionized water to obtain a hexamethylenetetramine solution. Add the mercuric sulfide silica gel obtained in Step 3 to the hexamethylenetetramine solution, impregnate at room temperature for 24 h, then put it into a blast drying oven and dry in an air atmosphere at 100 °C for 24 h to obtain hexamethylenetetramine-modified mercuric sulfide silica gel.

[0032] Comparative Example 1

[0033] A preparation method of activated silica gel, comprising: placing 300 g of water-resistant silica gel into 945 mL of a dilute nitric acid solution with a mass concentration of 3 wt%, stirring in a constant-temperature oil bath at 100 °C for 4 h, filtering with a sieve, washing 3 times with deionized water and absolute ethanol, then putting it into a blast drying oven and drying in an air atmosphere at 130 °C for 24 h to obtain activated silica gel.

[0034] This comparative example is the activated silica gel prepared in Step 1 of Example 1.

[0035] Comparative Example 2

[0036] A preparation method of mercuric salt-modified silica gel, comprising the following steps:

[0037] Step 1: Place 300 g of water - resistant silica gel into 945 mL of a dilute nitric acid solution with a mass concentration of 3 wt%, stir - treat it in a constant - temperature oil bath at 100 °C for 4 h, filter it with a sieve, wash it 3 times with deionized water and absolute ethanol, then put it into a forced - air drying oven and dry - treat it in an air atmosphere at 130 °C for 24 h to obtain activated silica gel;

[0038] Step 2: Add 1.5 mL of 68 wt% concentrated nitric acid to 12.5 mL of deionized water to prepare a dilute nitric acid solution. Dissolve 4.2699 g of mercuric nitrate hydrate in 14 mL of the dilute nitric acid solution to obtain a mercuric nitrate solution. Weigh 10 g of activated silica gel and add it to the mercuric nitrate solution, impregnate it at room temperature for 24 h, then put it into a forced - air drying oven and dry - treat it in an air atmosphere at 130 °C for 24 h to obtain mercury - salt - modified silica gel.

[0039] This comparative example is the mercury - salt - modified silica gel prepared by Steps 1 to 2 of Example 1.

[0040] Comparative Example 3

[0041] A preparation method of mercury sulfide silica gel includes the following steps:

[0042] Step 1: Place 300 g of water - resistant silica gel into 945 mL of a dilute nitric acid solution with a mass concentration of 3 wt%, stir - treat it in a constant - temperature oil bath at 100 °C for 4 h, filter it with a sieve, wash it 3 times with deionized water and absolute ethanol, then put it into a forced - air drying oven and dry - treat it in an air atmosphere at 130 °C for 24 h to obtain activated silica gel;

[0043] Step 2: Add 1.5 mL of 68 wt% concentrated nitric acid to 12.5 mL of deionized water to prepare a dilute nitric acid solution. Dissolve 4.2699 g of mercuric nitrate hydrate in 14 mL of the dilute nitric acid solution to obtain a mercuric nitrate solution. Weigh 10 g of activated silica gel and add it to the mercuric nitrate solution, impregnate it at room temperature for 24 h, then put it into a forced - air drying oven and dry - treat it in an air atmosphere at 130 °C for 24 h to obtain mercury - salt - modified silica gel;

[0044] Step 3: Add 3.6235 g of L - cysteine to 70 mL of ethylene glycol to obtain an L - cysteine solution. Add the mercury - salt - modified silica gel obtained in Step 2 to the L - cysteine solution, impregnate it at room temperature for 1 h, then transfer it to a 100 - mL polytetrafluoroethylene bottle, put it into a reaction kettle, carry out a hydrothermal reaction in an air atmosphere at 180 °C for 24 h, filter it and wash it 3 times with deionized water and absolute ethanol, put it into a forced - air drying oven and dry - treat it in an air atmosphere at 200 °C for 24 h to obtain mercury sulfide silica gel.

[0045] This comparative example is the mercuric sulfide silica gel prepared in Steps 1 to 3 of Example 1.

[0046] Comparative Example 4

[0047] A preparation method of hexamethylenetetramine-modified silica gel includes the following steps:

[0048] Step 1: Place 300 g of water-resistant silica gel into 945 mL of a dilute nitric acid solution with a mass concentration of 3 wt%, stir it in a constant-temperature oil bath at 100 °C for 4 h, filter it with a sieve, wash it 3 times with deionized water and absolute ethanol, then put it into a forced-air drying oven and dry it in an air atmosphere at 130 °C for 24 h to obtain activated silica gel;

[0049] Step 2: Dissolve 2.5 g of hexamethylenetetramine in 13 mL of deionized water to obtain a hexamethylenetetramine solution. Weigh 10 g of activated silica gel and add it to the hexamethylenetetramine solution, impregnate it at room temperature for 24 h, then put it into a forced-air drying oven and dry it in an air atmosphere at 100 °C for 24 h to obtain hexamethylenetetramine-modified silica gel.

[0050] In this comparative example, mercuric salt modification and mercuric sulfide treatment are not carried out, and the remaining steps are the same as those in Example 1.

[0051] Comparative Example 5

[0052] A preparation method of hexamethylenetetramine-modified mercuric salt silica gel includes the following steps:

[0053] Step 1: Place 300 g of water-resistant silica gel into 945 mL of a dilute nitric acid solution with a mass concentration of 3 wt%, stir it in a constant-temperature oil bath at 100 °C for 4 h, filter it with a sieve, wash it 3 times with deionized water and absolute ethanol, then put it into a forced-air drying oven and dry it in an air atmosphere at 130 °C for 24 h to obtain activated silica gel;

[0054] Step 2: Add 1.5 mL of 68 wt% concentrated nitric acid to 12.5 mL of deionized water to prepare a dilute nitric acid solution. Dissolve 4.2699 g of mercuric nitrate monohydrate in 14 mL of the dilute nitric acid solution to obtain a mercuric nitrate solution. Weigh 10 g of activated silica gel and add it to the mercuric nitrate solution, impregnate it at room temperature for 24 h, then put it into a forced-air drying oven and dry it in an air atmosphere at 130 °C for 24 h to obtain mercuric salt-modified silica gel;

[0055] Step 3: Dissolve 2.5 g of hexamethylenetetramine in 13 mL of deionized water to obtain a hexamethylenetetramine solution. Add the mercuric salt-modified silica gel obtained in Step 2 to the hexamethylenetetramine solution, impregnate it at room temperature for 24 h, then put it into a forced-air drying oven and dry it in an air atmosphere at 100 °C for 24 h to obtain hexamethylenetetramine-modified mercuric salt silica gel.

[0056] In this comparative example, mercuric sulfide treatment was not carried out, and the remaining steps were the same as those in Example 1.

[0057] Figure 1 XRD patterns of the activated silica gel prepared in Comparative Example 1, the mercuric sulfide silica gel prepared in Comparative Example 3, and the hexamethylenetetramine-modified mercuric sulfide silica gel prepared in Example 1 are shown. As shown in the figure, the XRD pattern of the activated silica gel shows a "bread-like peak", indicating that the activated silica gel is amorphous. New characteristic peaks appear at 2θ = 26.3°, 30.5°, 43.7°, and 51.7° in the mercuric sulfide silica gel, which are attributed to the characteristic peaks of mercuric sulfide, indicating that the silica gel was successfully modified with mercuric sulfide. After modification with hexamethylenetetramine, the peak intensity of the XRD pattern decreased slightly, and a new characteristic peak appeared at 2θ = 17.6°, which is attributed to the characteristic peak of hexamethylenetetramine. This indicates that the mercuric sulfide silica gel was successfully modified with hexamethylenetetramine.

[0058] Figure 2 FT-IR spectra of the activated silica gel, mercuric sulfide silica gel, and hexamethylenetetramine-modified mercuric sulfide silica gel are shown. As shown in the figure, the peaks at 468, 802, and 1110 cm -1 are the skeletal vibration peaks of Si-O-Si in the silica gel. The broad and strong band centered at 3443 cm -1 (Si-OH) and the weak absorption at 1036 cm -1 (H-OH) indicate the presence of water. The silica gel shows a characteristic peak of NO -1 at 1387 cm 3 - , which is attributed to the activation treatment with dilute nitric acid. The disappearance of the peak at this position in the mercuric sulfide silica gel and the hexamethylenetetramine-modified silica gel also indicates a change in the form of mercury. After modification with hexamethylenetetramine, stretching vibrations of C-H bonds appear at 2913 cm -1 , bending vibrations of C-H bonds appear at 681 cm -1 , and the region near 1468 cm -1 is the stretching vibration frequency region of C-N bonds, indicating that the modification with hexamethylenetetramine was successful.

[0059] Figure 3 SEM images of the activated silica gel (a, b), mercuric sulfide silica gel (c, d), and hexamethylenetetramine-modified mercuric sulfide silica gel (e, f) are shown. As shown in the figure, the average particle size of the silica gel is 3 - 4 mm, and it can be clearly seen that the surface becomes rough after modification. Some pore collapses were observed, resulting in a certain change in the pore structure, which is caused by the activation of the silica gel. The mercuric sulfide silica gel shows a cauliflower-like structure on the surface, and a protective film is deposited on the surface of the hexamethylenetetramine-modified mercuric sulfide silica gel, making the distribution of active sites on the surface more uniform.

[0060] Figure 4TGA spectra of mercuric sulfide silica gel and hexamethylenetetramine modified mercuric sulfide silica gel. Mercuric sulfide silica gel mainly loses 13.6% of its weight at 300 - 420 °C, which is attributed to the decomposition of mercuric sulfide. Hexamethylenetetramine modified mercuric sulfide silica gel has two weight loss stages. It loses 13.6% of its weight in the range of 140 - 300 °C, attributed to the decomposition of hexamethylenetetramine, and loses 15.9% of its weight in the range of 300 - 420 °C, attributed to the decomposition of mercuric sulfide.

[0061] Application Example

[0062] The silica gels prepared in Example 1 and Comparative Examples 1 - 5 were respectively subjected to static iodine adsorption tests. The specific test method is as follows:

[0063] Weigh 3 g of iodine (or 3 mL of methyl iodide) and place it in a weighing bottle with a specification of 25 mm × 25 mm. Then place the weighing bottle at the bottom of a crucible with a height of 13 cm. After that, cover a quartz sand sheet on the weighing bottle. Put 1 g of silica gel into the porous basket on the quartz sand sheet. Finally, cover the lid and place it in a forced-air drying oven at 130 °C. After reacting for 24 h, take out the container and cool it to room temperature. Finally, weigh the adsorbed silica gel using an electronic balance, set three replicates, and calculate the adsorption capacity using the following formula.

[0064] q t =(m t -m 0 ) / m 0 ×1000

[0065] Where q t (mg / g) represents the adsorption capacity of I 2 and CH 3 I at time t, m 0 (g) and m t (g) respectively represent the initial mass of the silica gel and the mass at time t.

[0066] The results are shown in Table 1. The hexamethylenetetramine modified mercuric sulfide silica gel of the present invention can simultaneously capture elemental iodine and methyl iodide, has a strong adsorption ability for elemental iodine and methyl iodide, the adsorption capacity for elemental iodine reaches 627 mg / g, and the adsorption capacity for methyl iodide reaches 411 mg / g, which is significantly higher than that of the comparative examples.

[0067] Table 1

[0068]

[0069] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those skilled in the art, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the examples shown and described herein.

Claims

1. A method for preparing hexamethylenetetramine modified mercuric sulfide silica gel, characterized in that: The following steps are involved: Step 1, placing silica gel in a dilute nitric acid solution for activation treatment to obtain activated silica gel; Step 2: adding the activated silica gel into a mercuric nitrate solution, performing an immersion treatment, and drying to obtain mercury salt-modified silica gel; Step 3, adding the mercury salt modified silica gel obtained in step 2 into the L-cysteine ​​solution for immersion treatment, then performing a hydrothermal reaction, filtering, washing and drying to obtain mercuric sulfide silica gel; Step 4: adding the mercuric sulfide silica gel obtained in step 3 into a hexamethylenetetramine solution, performing immersion treatment, and drying to obtain hexamethylenetetramine-modified mercuric sulfide silica gel.

2. The method for preparing hexamethylenetetramine-modified mercuric sulfide silica gel according to claim 1, characterized in that: In the step 1, the concentration of the dilute nitric acid solution is 3-5wt%; the silica gel is water-resistant silica gel; and the mass volume ratio of the silica gel to the dilute nitric acid solution is 1g:3-5mL.

3. The method for preparing hexamethylenetetramine modified mercuric sulfide silica gel according to claim 1, characterized in that: In the step 1, the specific method of the activation treatment is: stirring at 90-110° C. for 3-5 hours, filtering, washing with deionized water and anhydrous ethanol for 1-5 times in sequence, and then drying in an air atmosphere at 110-150° C. for 20-28 hours.

4. The method for preparing hexamethylenetetramine modified mercuric sulfide silica gel according to claim 1, characterized in that: In the step 2, the preparation method of the mercuric nitrate solution is: adding concentrated nitric acid with a concentration of 65-68wt% to deionized water to prepare a dilute nitric acid solution, and then dissolving hydrated mercuric nitrate in the dilute nitric acid solution to obtain the mercuric nitrate solution; wherein the volume ratio of the concentrated nitric acid to the deionized water is 1:8-10; and the mass volume ratio of the hydrated mercuric nitrate to the dilute nitric acid solution is 0.25-0.35g:1mL.

5. The method for preparing hexamethylenetetramine modified mercuric sulfide silica gel according to claim 1, characterized in that: In the step 2, the mass volume ratio of activated silica gel to mercuric nitrate solution is 0.5-1.0 g:1 mL; the immersion treatment is: immersing at room temperature for 20-28 hours; and the drying is: drying in an air atmosphere at 110-150° C. for 20-28 hours.

6. The method for preparing hexamethylenetetramine modified mercuric sulfide silica gel according to claim 1, characterized in that: In the step 3, the preparation method of the L-cysteine ​​solution is: adding L-cysteine ​​to ethylene glycol to obtain an L-cysteine ​​solution with a concentration of 45 to 55 g / L.

7. The method for preparing hexamethylenetetramine modified mercuric sulfide silica gel according to claim 1, characterized in that: In the step three, the immersion treatment is: immersing at room temperature for 0.5 to 2 hours; the hydrothermal reaction is: reacting in a polytetrafluoroethylene container at 170 to 190° C. in an air atmosphere for 20 to 28 hours; the washing is: washing with deionized water and anhydrous ethanol in sequence for 1 to 5 times; the drying is: drying at 180 to 220° C. in an air atmosphere for 20 to 28 hours; the volume mass ratio of the L-cysteine ​​solution to the activated silica gel in step two is 5 to 10 mL: 1 g.

8. The method for preparing hexamethylenetetramine modified mercuric sulfide silica gel according to claim 1, characterized in that: In the step 4, the preparation method of the hexamethylenetetramine solution is: dissolving hexamethylenetetramine in deionized water to obtain a hexamethylenetetramine solution with a concentration of 150 to 250 g / L.

9. The method for preparing hexamethylenetetramine modified mercuric sulfide silica gel according to claim 1, characterized in that: In the step 4, the impregnation treatment is: impregnation at room temperature for 20 to 28 hours; the drying is: drying in an air atmosphere of 80 to 120° C. for 20 to 28 hours; the volume mass ratio of the hexamethylenetetramine solution to the activated silica gel in step 2 is 1 to 2 mL: 1 g.

10. Use of hexamethylenetetramine-modified mercuric sulfide silica gel prepared by the preparation method according to any one of claims 1 to 9 in capturing radioactive gaseous iodine.

Images