Preparation of silica aerogel grafted choline hydroxide material and application of silica aerogel grafted choline hydroxide material in iodine vapor capture

Abstract

The invention discloses a preparation method of a silicon dioxide aerogel grafted choline hydroxide material, which comprises the following steps: dissolving 3-glycidoxytrimethoxysilane in absolute ethyl alcohol, and carrying out ultrasonic oscillation until the solution is completely and uniformly mixed; adding water and a sodium hydroxide solution into the mixture, adjusting the pH value to be alkaline, continuously carrying out ultrasonic uniform mixing, adding silicon dioxide aerogel powder, heating in a water bath, carrying out suction filtration to obtain powder, and washing the powder with absolute ethyl alcohol for later use; and adding a choline hydroxide solution with a certain concentration into absolute ethyl alcohol, pouring the powder into the solution, heating in a water bath, and carrying out suction filtration and drying on the solution to obtain the silicon dioxide aerogel grafted choline hydroxide material. The method has the beneficial effects that the choline hydroxide greatly improves the adsorption capacity of the silicon dioxide aerogel to iodine vapor, so that the silicon dioxide aerogel grafted choline hydroxide material has better capture capacity to the iodine vapor; the adsorption on iodine vapor is facilitated; and the preparation cost is low.

Description

Technical Field

[0001] The invention belongs to the environmental protection field of using aerogel materials for adsorbing radioactive iodine vapor in the environment, and specifically relates to the preparation of a silicon dioxide aerogel grafted choline hydroxide material and its application in capturing iodine vapor. Background Art

[0002] As a promising energy source, nuclear energy has the potential to replace traditional fossil fuels with its inherent advantages such as cleanliness, high efficiency and relatively low cost. With the continuous development of nuclear energy, the problem of harmful radioactive spent fuel has become increasingly prominent. Non-radioactive isotopes, especially radioactive iodine (I-129 and I-131), have a long half-life and are very harmful to the environment and the human body. Radioactive iodine is quickly absorbed by the thyroid gland, resulting in concentrated radiation exposure in this organ. This may cause thyroiditis, thyroid dysfunction, and even increase the risk of thyroid cancer.

[0003] The development of an adsorbent that can efficiently adsorb iodine has important practical significance. At present, common materials used for iodine adsorption on the market include covalent organic frameworks (COFs), metal organic frameworks (MOFs), zeolites, silver-based materials and graphene composites. Although these materials perform well in the adsorption of iodine, their preparation process is usually complicated and costly, and harmful substances may be produced during the manufacturing process, which limits their popularity and promotion in practical applications. In contrast, aerogel materials have become a more ideal choice for iodine adsorbents due to their low density, high porosity, environmental harmlessness and low cost. Therefore, as a new type of adsorbent, aerogel materials have broad development prospects and are expected to be more widely used in the field of iodine adsorption. Summary of the invention

[0004] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0005] In order to achieve these purposes and other advantages according to the present invention, a method for preparing a silica aerogel grafted choline hydroxide material is provided, comprising the following steps:

[0006] Step 1: dissolve 3-glycidyl propoxy trimethoxy silane in anhydrous ethanol, and ultrasonically vibrate at room temperature until the solution is completely mixed; then add water and sodium hydroxide solution, adjust the pH to alkaline, and continue to ultrasonically mix;

[0007] Step 2: Add silica aerogel powder to the solution of step 1, heat in a water bath, filter and obtain powder, and rinse the powder with anhydrous ethanol for later use;

[0008] Step 3: Add a certain concentration of choline hydroxide solution into anhydrous ethanol, pour the powder obtained in step 2 into the solution, heat it in a water bath for a period of time, and then filter and dry the solution to obtain a silica aerogel grafted choline hydroxide material.

[0009] Preferably, in the step 1, the volume ratio of 3-glycidyl propoxy trimethoxy silane, anhydrous ethanol, water and sodium hydroxide solution is 1-2:18-19:1:1, the concentration of 3-glycidyl propoxy trimethoxy silane is 98%wt, the concentration of sodium hydroxide solution is 0.01-0.03M, the pH is adjusted to 8-10, and the ultrasonic frequency is 40-60kHz.

[0010] Preferably, in step 2, the silica aerogel powder is commercially available hydrophobic silica aerogel, the water bath heating temperature is 40-60°C, and the heating is performed for 12h-24h. During the filtration process, the powder is rinsed with anhydrous ethanol 2-3 times. After filtration, the powder adheres to the filter paper, and the filter paper is rinsed with anhydrous ethanol, carefully scraped with a spoon, and placed in a culture dish for later use.

[0011] Preferably, in the step three, the concentration of the choline hydroxide solution is 44%wt, the volume ratio of the choline hydroxide solution to anhydrous ethanol is 1-2:18-19, the water bath temperature is 40-60°C, the water bath heating time is 12-24h, the powder adheres to the filter paper after filtration, and is carefully scraped into a culture dish with a spoon, the drying oven temperature is 45-60°C, and the drying time is 12-24h.

[0012] The present invention also uses a silicon dioxide aerogel grafted choline hydroxide material in capturing iodine vapor.

[0013] The present invention has at least the following beneficial effects:

[0014] (1) Choline hydroxide is chemically grafted onto the surface of silica aerogel through the crosslinking agent 3-glycidyl propoxy trimethoxy silane. Iodine vapor can be effectively adsorbed on the surface of the material. The porous structure of the aerogel particles also leads to its better ability to capture iodine vapor.

[0015] (2) The present invention modifies the silica aerogel, and the electrostatic effect of choline hydroxide can provide good active sites, which greatly increases the adsorption capacity of the modified silica aerogel for iodine vapor, which is beneficial to the adsorption of iodine vapor;

[0016] (3) The preparation process of the present invention is simple, the preparation cost is low, and it is green and environmentally friendly.

[0017] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a SEM image of the silica aerogel grafted choline hydroxide material prepared in Example 5;

[0019] Figure 2 This is a SEM image of the silica aerogel grafted choline hydroxide material prepared in Example 5 after adsorbing iodine vapor;

[0020] Figure 3 This is a physical picture of the silica aerogel grafted choline hydroxide material prepared in Example 5;

[0021] Figure 4 This is a physical picture of the silica aerogel grafted choline hydroxide material prepared in Example 5 after adsorbing iodine vapor;

[0022] Figure 5 The FT-IR result diagram of the silica aerogel grafted with choline hydroxide material before and after iodine vapor adsorption in Example 5 and the commercially available silica aerogel in Comparative Example 2;

[0023] Figure 6 This is an adsorption curve diagram of the silica aerogel grafted choline hydroxide material prepared in Example 5;

[0024] Figure 7 The XRD results of the silica aerogel grafted with choline hydroxide material and adsorbed with iodine vapor prepared in Example 5 and the commercially available silica aerogel in Comparative Example 2;

[0025] Figure 8 This is a thermal weight loss curve of the silica aerogel grafted choline hydroxide material prepared in Example 5;

[0026] Fig. 9 This is a thermogravimetric analysis curve of the silica aerogel grafted choline hydroxide material prepared in Example 5;

[0027] Fig.10 This is a graph showing the adsorption performance of the silica aerogel grafted choline hydroxide material prepared in Example 5 to gaseous iodine under different humidity environments;

[0028] Fig.11 This is a pseudo-first-order kinetic model diagram of the adsorption of the silica aerogel grafted choline hydroxide material prepared in Example 5;

[0029] Fig.12 This is a diagram of the adsorption quasi-second-order kinetic model of the silica aerogel grafted choline hydroxide material prepared in Example 5;

[0030] Fig.13 This is the adsorption-desorption curve of the silica aerogel grafted choline hydroxide material prepared in Example 5 before and after the adsorption of iodine vapor. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0032] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0033] Example 1

[0034] A method for preparing a silica aerogel grafted choline hydroxide material comprises the following steps:

[0035] Step 1: Dissolve 2 mL of 3-glycidyl propoxy trimethoxy silane in 18 mL of anhydrous ethanol and ultrasonically vibrate at room temperature until the solution is completely mixed; then add 1 mL of water and 1 mL of 0.01 M sodium hydroxide solution, adjust the pH to alkaline, and continue ultrasonically mixing;

[0036] Step 2: Add 1 g of silica aerogel powder to the solution of step 1, heat the beaker containing the solution in a 60° C. water bath for 12 h, and then filter to obtain powder. Rinse the powder with anhydrous ethanol for 3 times and set aside;

[0037] Step 3: Add 2 mL of 44% wt choline hydroxide solution into 18 mL of anhydrous ethanol, pour the powder obtained in step 2 into the solution, heat in a 45° C. water bath for 12 h, then filter the solution and dry it in a drying oven at 45° C. for 24 h to obtain a silica aerogel grafted choline hydroxide material.

[0038] Example 2

[0039] A method for preparing a silica aerogel grafted choline hydroxide material comprises the following steps:

[0040] Step 1: Dissolve 2 mL of 3-glycidyl propoxy trimethoxy silane in 18 mL of anhydrous ethanol and ultrasonically vibrate at room temperature until the solution is completely mixed; then add 1 mL of water and 1 mL of 0.01 M sodium hydroxide solution, adjust the pH to alkaline, and continue ultrasonically mixing;

[0041] Step 2: Add 1 g of silica aerogel powder to the solution of step 1, heat the beaker containing the solution in a 60° C. water bath for 12 h, and then filter to obtain powder. Rinse the powder with anhydrous ethanol for 3 times and set aside;

[0042] Step 3: Add 2 mL of 44% wt choline hydroxide solution into 18 mL of anhydrous ethanol, pour the powder obtained in step 2 into the solution, heat in a 60° C. water bath for 12 h, then filter the solution and dry it in a drying oven at 45° C. for 24 h to obtain a silica aerogel grafted choline hydroxide material.

[0043] Example 3

[0044] A method for preparing a silica aerogel grafted choline hydroxide material comprises the following steps:

[0045] Step 1: Dissolve 2 mL of 3-glycidyl propoxy trimethoxy silane in 18 mL of anhydrous ethanol and ultrasonically vibrate at room temperature until the solution is completely mixed; then add 1 mL of water and 1 mL of 0.01 M sodium hydroxide solution, adjust the pH to alkaline, and continue ultrasonically mixing;

[0046] Step 2: Add 1 g of silica aerogel powder to the solution of step 1, heat the beaker containing the solution in a 60° C. water bath for 12 h, and then filter to obtain powder. Rinse the powder with anhydrous ethanol for 3 times and set aside;

[0047] Step 3: Add 2 mL of 44% wt choline hydroxide solution into 18 mL of anhydrous ethanol, pour the powder obtained in step 2 into the solution, heat in a 45° C. water bath for 24 h, then filter the solution and dry it in a drying oven at 45° C. for 24 h to obtain a silica aerogel grafted choline hydroxide material.

[0048] Example 4

[0049] A method for preparing a silica aerogel grafted choline hydroxide material comprises the following steps:

[0050] Step 1: Dissolve 2 mL of 3-glycidyl propoxy trimethoxy silane in 18 mL of anhydrous ethanol and ultrasonically vibrate at room temperature until the solution is completely mixed; then add 1 mL of water and 1 mL of 0.01 M sodium hydroxide solution, adjust the pH to alkaline, and continue ultrasonically mixing;

[0051] Step 2: Add 1 g of silica aerogel powder to the solution of step 1, heat the beaker containing the solution in a 60° C. water bath for 12 h, and then filter to obtain powder. Rinse the powder with anhydrous ethanol for 3 times and set aside;

[0052] Step 3: Add 2 mL of 44% wt choline hydroxide solution into 18 mL of anhydrous ethanol, pour the powder obtained in step 2 into the solution, heat in a 60° C. water bath for 24 h, then filter the solution and dry it in a drying oven at 45° C. for 24 h to obtain a silica aerogel grafted choline hydroxide material.

[0053] Example 5

[0054] A method for preparing a silica aerogel grafted choline hydroxide material comprises the following steps:

[0055] Step 1: Dissolve 2 mL of 3-glycidyl propoxy trimethoxy silane in 18 mL of anhydrous ethanol and ultrasonically vibrate at room temperature until the solution is completely mixed; then add 1 mL of water and 1 mL of 0.01 M sodium hydroxide solution, adjust the pH to alkaline, and continue ultrasonically mixing;

[0056] Step 2: Add 1 g of silica aerogel powder to the solution of step 1, heat the beaker containing the solution in a 60° C. water bath for 24 h, and then filter to obtain powder. Rinse the powder with anhydrous ethanol for 3 times and set aside;

[0057] Step 3: Add 2 mL of 44% wt choline hydroxide solution into 18 mL of anhydrous ethanol, pour the powder obtained in step 2 into the solution, heat in a 60° C. water bath for 24 h, then filter the solution and dry it in a drying oven at 45° C. for 24 h to obtain a silica aerogel grafted choline hydroxide material.

[0058] Example 6

[0059] A method for preparing a silica aerogel grafted choline hydroxide material comprises the following steps:

[0060] Step 1: Dissolve 2 mL of 3-glycidyl propoxy trimethoxy silane in 18 mL of anhydrous ethanol and ultrasonically vibrate at room temperature until the solution is completely mixed; then add 1 mL of water and 1 mL of 0.01 M sodium hydroxide solution, adjust the pH to alkaline, and continue ultrasonically mixing;

[0061] Step 2: Add 1 g of silica aerogel powder to the solution of step 1, heat the beaker containing the solution in a 60° C. water bath for 24 h, and then filter to obtain powder. Rinse the powder with anhydrous ethanol for 3 times and set aside;

[0062] Step 3: Add 1 mL of 44% wt choline hydroxide solution to 19 mL of anhydrous ethanol, pour the powder obtained in step 2 into the solution, heat in a 60° C. water bath for 24 h, then filter the solution and dry it in a drying oven at 45° C. for 24 h to obtain a silica aerogel grafted choline hydroxide material.

[0063] Application Examples

[0064] The silica aerogel grafted choline hydroxide material prepared in Examples 1 to 6 was subjected to a gaseous iodine adsorption experiment; the method is: non-radioactive iodine was used to replace the radioactive iodine; first, excess iodine was placed at the bottom of a 500mL gas collecting bottle, 0.05g of silica aerogel grafted choline hydroxide material (Examples 1 to 6) was placed in a crucible, the crucible was placed in the gas collecting bottle, the bottle cap was covered, and the gas collecting bottle was placed in a 75°C oven. At different time intervals, the longest adsorption was 70h before taking it out of the oven, cooling it to room temperature, and the iodine vapor content adsorbed by the silica aerogel grafted choline hydroxide material was determined by the gravimetric method. The calculation formula is as follows:

[0065] Q=(m 2 -m 1 ) / m 1 ×100wt%

[0066] Where Q is the adsorption amount of iodine, m 1 (mg) and m 2 (mg) are the weights of the silica aerogel grafted choline hydroxide material before and after capturing iodine. Three adsorption experiments were carried out in parallel for each material and the average value was taken.

[0067] Figure 1 This is a SEM image of the silica aerogel grafted with choline hydroxide prepared in Example 5. It can be seen from the figure that the grafted silica aerogel material has a granular structure and a rough surface, which is conducive to the adsorption of iodine vapor;

[0068] Figure 2 This is a SEM image of the silica aerogel grafted choline hydroxide material prepared in Example 5 after adsorbing iodine vapor. The image shows that the material surface has dense pores, and the surface is rough, with a large specific surface area, and can effectively contact iodine;

[0069] Figure 3 This is a physical picture of the silica aerogel grafted choline hydroxide material prepared in Example 5, which is in the form of small white particles, which is easy to put into a container and meets the actual application scenario of iodine adsorption;

[0070] Figure 4 This is a photo of the silica aerogel grafted choline hydroxide material prepared in Example 5 after absorbing iodine vapor. After absorbing iodine vapor, the color changes to dark brown. From the color change, it can be clearly seen that the material has a capture effect on iodine vapor;

[0071] Figure 5 The FT-IR results of the silica aerogel grafted with choline hydroxide in Example 5 before and after iodine vapor adsorption and the commercially available silica aerogel in Comparative Example 2 (SiO 2 Aerogel refers to commercially available silica aerogel, modified SiO 2Aerogel refers to silica aerogel grafted with choline hydroxide material, modified SiO 2 Aerogel-I refers to the silica aerogel grafted with choline hydroxide material after the iodine is adsorbed. The 3500cm -1 The height of the peak at is significantly increased. This peak is caused by the stretching vibration of -OH, which indicates that -OH on the material may have a strong adsorption effect on iodine.

[0072] Figure 6 This is the adsorption curve of the silica aerogel grafted choline hydroxide material prepared in Example 5. It can be seen that the material has a high adsorption efficiency for gaseous iodine. As time increases, the iodine capture amount increases accordingly, and the adsorption equilibrium is basically reached within 15 hours, and the maximum adsorption amount is as high as 1362.43 mg / g;

[0073] Figure 7 The xrd results of the silica aerogel prepared in Example 5 after grafting choline hydroxide material and iodine vapor adsorption and the commercially available silica aerogel in Comparative Example 2 (SiO 2 Aerogel refers to commercially available silica aerogel, modified SiO 2 Aerogel refers to silica aerogel grafted with choline hydroxide material, modified SiO 2 Aerogel-I refers to the silica aerogel grafted with choline hydroxide material after the iodine is adsorbed. After the iodine vapor is adsorbed, the peak at 23° disappears, indicating that the interaction between iodine and the material destroys the structure of the raw material, and also indicates that the material and iodine are effectively combined;

[0074] Figure 8 , Fig. 9 This is a thermal weight loss curve of the silica aerogel grafted choline hydroxide material prepared in Example 5 of the present invention (SiO 2 Aerogel refers to commercially available silica aerogel, modified SiO 2 Aerogel refers to silica aerogel grafted with choline hydroxide material, modified SiO 2 Aerogel-I refers to the silica aerogel grafted with choline hydroxide material after the iodine adsorption is completed. As shown in the figure, the material has a mass loss of less than 20% before 200°C and has good thermal stability;

[0075] Fig.10 The adsorption performance of the silica aerogel grafted choline hydroxide material prepared in Example 5 of the present invention on gaseous iodine under different humidity environments shows that the humidity of 50% has little effect on the adsorption performance of the material;

[0076] Fig.11 , Fig.12The adsorption kinetic model of the silica aerogel grafted choline hydroxide material prepared in Example 5 of the present invention is more consistent with the pseudo-second-order adsorption kinetics, proving that the pores of the material play a role in capturing iodine vapor;

[0077] Fig.13 The adsorption-desorption curves of the silica aerogel grafted choline hydroxide material prepared in Example 5 of the present invention before and after the adsorption of iodine vapor indicate that the high porosity of the material is more conducive to capturing iodine vapor.

[0078] Comparative Example 1

[0079] A method for preparing a silica aerogel grafted choline hydroxide material comprises the following steps:

[0080] Step 1: Dissolve 2 mL of 3-glycidyl propoxy trimethoxy silane in 18 mL of anhydrous ethanol and ultrasonically vibrate at room temperature until the solution is completely mixed; then add 1 mL of water and 1 mL of 0.01 M sodium hydroxide solution, adjust the pH to alkaline, and continue ultrasonically mixing;

[0081] Step 2: Add 1 g of silica aerogel powder to the solution of step 1, heat the beaker containing the solution in a 60° C. water bath for 24 h, filter and obtain powder, rinse the powder with anhydrous ethanol three times to obtain GTPMS-modified silica aerogel; then use the GTPMS-modified silica aerogel to adsorb iodine vapor at 75° C. according to the method in the application example, and the adsorption amount after 18 h is 32.2 mg / g.

[0082] Comparative Example 2

[0083] Commercially available silica aerogel was used as the adsorption material, and iodine vapor was adsorbed at 75° C. according to the method of the application example. The adsorption amount was 21.2 mg / g after 18 hours of adsorption.

[0084] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A method for preparing a silica aerogel grafted choline hydroxide material, characterized in that: The following steps are involved: Step 1: dissolve 3-glycidyl propoxy trimethoxy silane in anhydrous ethanol, and ultrasonically vibrate at room temperature until the solution is completely mixed; then add water and sodium hydroxide solution, adjust the pH to alkaline, and continue to ultrasonically mix; Step 2: Add silica aerogel powder to the solution of step 1, heat in a water bath, filter and obtain powder, and rinse the powder with anhydrous ethanol for later use; Step 3: Add a certain concentration of choline hydroxide solution into anhydrous ethanol, pour the powder obtained in step 2 into the solution, heat it in a water bath for a period of time, and then filter and dry the solution to obtain a silica aerogel grafted choline hydroxide material.

2. The method for preparing the silica aerogel grafted choline hydroxide material according to claim 1, characterized in that: In the step 1, the volume ratio of 3-glycidyl propoxy trimethoxy silane, anhydrous ethanol, water and sodium hydroxide solution is 1-2:18-19:1:1, the concentration of 3-glycidyl propoxy trimethoxy silane is 98%wt, the concentration of sodium hydroxide solution is 0.01-0.03M, the pH is adjusted to 8-10, and the ultrasonic frequency is 40-60kHz.

3. The method for preparing the silica aerogel grafted choline hydroxide material according to claim 1, characterized in that: In the step 2, the silica aerogel powder is commercially available hydrophobic silica aerogel, and the water bath heating temperature is 40-60° C. for 12-24 hours. During the filtration process, the powder is rinsed with anhydrous ethanol 2-3 times. After filtration, the powder adheres to the filter paper, and the filter paper is rinsed with anhydrous ethanol, carefully scraped with a spoon, and placed in a culture dish for later use.

4. The method for preparing the silica aerogel grafted choline hydroxide material according to claim 1, characterized in that: In the step 3, the concentration of the choline hydroxide solution is 44%wt, the volume ratio of the choline hydroxide solution to anhydrous ethanol is 1-2:18-19, the water bath temperature is 40-60°C, the water bath heating time is 12-24h, the powder adheres to the filter paper after filtration, and is carefully scraped into a culture dish with a spoon, the drying oven temperature is 45-60°C, and the drying time is 12-24h.

5. Use of the silica aerogel grafted choline hydroxide material prepared by the preparation method according to any one of claims 1 to 4 in capturing iodine vapor.

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