Bismuth-based adsorbent, preparation method and application thereof

Abstract

The invention belongs to the field of iodine adsorption material technology, and in particular to a kind of bismuth-based adsorbent and its preparation method and application. The present invention is with P123 as structure directing agent, and its surface is rich in silanol, with tetraethyl orthosilicate as silicon source, bismuth salt is bismuth source, and washing, drying and calcining are carried out successively after hydrothermal synthesis, bismuth is loaded on SBA 15 surface, bismuth-based adsorbent (Bi SBA 15) is obtained, SBA 15 is the molecular sieve with porous structure, Bi has affinity and stability to silica substrate to iodine vapor, and the adsorption capacity of obtained bismuth-based adsorbent to iodine vapor is high, strong stability. The present invention prepares bismuth-based iodine adsorbent under neutral conditions, without the need to add acid source, more environmentally friendly, while the present invention uses " one-step method ", directly bismuth source is doped in mesoporous material pore wall during synthesis of SBA 15, simple to operate, with low cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of iodine adsorption materials, and in particular relates to a bismuth-based adsorbent and a preparation method and application thereof. Background Art

[0002] With the continuous development of nuclear energy, spent fuel reprocessing waste gas (including 129 I. 131 I. 3 H. 14 C. 85 Kr and 133 The treatment of Xe, etc. has attracted much attention. Iodine is a radioactive nuclide with a half-life of about 8 days ( 131 I) to 1.6×10 7 Year( 129 I), 129 Iodine is highly toxic, highly mobile, and has a long half-life, causing serious environmental problems. Iodine vapor is sublimated iodine. Inhalation of iodine vapor can damage the respiratory tract, leading to tracheitis, pneumonia, and even pulmonary edema. In severe cases, it can lead to poisoning and death. Exposure to radioactive iodine can also cause metabolic disorders, mental retardation, and an increased risk of thyroid cancer. Therefore, the removal of iodine vapor from nuclear waste is essential.

[0003] Radioactive iodine is widely present in nuclear waste gas, mostly in the form of elemental iodine. Existing technologies typically use adsorption to remove iodine. Solid adsorption methods primarily include activated carbon adsorption, microporous exchange resin adsorption, silver exchange or silver-impregnated zeolite adsorption, and alumina adsorption. However, these current adsorbents all suffer from low iodine adsorption capacity. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a bismuth-based adsorbent and its preparation method and application. The bismuth-based adsorbent prepared by the preparation method of the present invention has a high adsorption capacity for iodine.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a bismuth-based adsorbent, comprising the following steps:

[0007] Adding homogeneous solution A dropwise to homogeneous solution B to obtain a homogeneous sol, wherein the homogeneous solution A comprises ethyl orthosilicate, persulfate and water, and the homogeneous solution B comprises bismuth salt, P123 and water;

[0008] The homogeneous sol is subjected to hydrothermal synthesis and then solid-liquid separation, and the obtained solid is washed, dried and calcined in sequence to obtain the bismuth-based adsorbent.

[0009] Preferably, the usage ratio of ethyl orthosilicate and persulfate is 4.6 mL: 0.0495-0.2 g.

[0010] Preferably, the mass ratio of the bismuth salt to P123 is 0.396-1.584:2.

[0011] Preferably, the dropping rate is 60 to 80 drops / min.

[0012] Preferably, the temperature of the hydrothermal synthesis is 80-130° C., and the time is 12-48 hours.

[0013] Preferably, the drying temperature is 40-100° C. and the drying time is 8-24 hours.

[0014] Preferably, the calcination temperature is 450-550° C. and the calcination time is 4-12 hours.

[0015] Preferably, the calcination is carried out in an argon-hydrogen mixed gas atmosphere, and the volume concentration of hydrogen in the argon-hydrogen mixed gas is 3-5%.

[0016] The present invention also provides a bismuth-based adsorbent obtained by the preparation method described in the above technical solution, comprising SBA-15 and bismuth, wherein the bismuth is loaded on the surface of the SBA-15.

[0017] The present invention also provides the use of the bismuth-based adsorbent described in the above technical solution in adsorbing iodine.

[0018] The present invention provides a method for preparing a bismuth-based adsorbent, comprising the following steps:

[0019] Adding homogeneous solution A dropwise to homogeneous solution B to obtain a homogeneous sol, wherein the homogeneous solution A comprises ethyl orthosilicate, persulfate and water, and the homogeneous solution B comprises bismuth salt, P123 and water;

[0020] The homogeneous sol is subjected to hydrothermal synthesis and then solid-liquid separation, and the obtained solid is washed, dried and calcined in sequence to obtain the bismuth-based adsorbent.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention uses surfactant P123 as a structure-directing agent, the surface of which is rich in silanol groups, TEOS (tetraethyl orthosilicate) as a silicon source, and bismuth salt as a bismuth source. After hydrothermal synthesis, washing, drying and calcination are performed in sequence, and bismuth is loaded on the surface of SBA-15 to obtain a bismuth-based adsorbent (Bi-SBA-15). SBA-15 is a molecular sieve with a porous structure. Bi has affinity for iodine vapor and stability on a silicon dioxide substrate. The prepared bismuth-based adsorbent has a high adsorption capacity for iodine vapor, and the adsorption capacity ranges from 245.9 to 625.5 mg / g.

[0023] Furthermore, the synthesis of traditional SBA-15 is carried out under acidic conditions and requires the addition of an acid source such as HCl, HNO3 or HBr. The homogeneous sol of the present invention includes tetraethyl orthosilicate, persulfate, bismuth salt, P123 and water. The homogeneous sol is hydrothermally synthesized to prepare SBA-15 without the need to add an acid source, thereby achieving the preparation of a bismuth-based iodine adsorbent under neutral conditions, which is more environmentally friendly. At the same time, the present invention directly dopes the bismuth source into the pore wall of the SBA-15 mesoporous material during the hydrothermal synthesis of SBA-15, adopts a "one-step method" to prepare the bismuth-based adsorbent, which is simple to operate and low in cost.

[0024] The present invention also provides the use of the bismuth-based adsorbent described in the above technical solution in iodine adsorption. The bismuth-based adsorbent of the present invention has a high adsorption capacity for iodine vapor. At the same time, Bi has stability on the silica substrate. The bismuth-based adsorbent has good radiation stability and good specific surface area and pore size characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 This is a flow chart of a method for preparing an adsorbent according to an embodiment of the present invention;

[0027] Figure 2 The figures are the physical pictures of the products of each step in the preparation process of the adsorbent in Comparative Example 1 and Examples 1 to 6, wherein the upper row is the product before calcination and the lower row is the product after calcination;

[0028] Figure 3 The XRD small-angle patterns of SBA-15 prepared in Comparative Example 1 and Bi-SBA-15 prepared in Examples 1 to 6 are shown;

[0029] Figure 4 XRD wide-angle patterns of SBA-15 prepared in Comparative Example 1 and Bi-SBA-15 prepared in Examples 1 to 6;

[0030] Figure 5 XRD wide-angle spectra of the Bi-SBA-15 materials prepared in Examples 1 to 6 after adsorption of iodine vapor;

[0031] Figure 6 The adsorption capacity of iodine vapor by the SBA-15 prepared in Comparative Example 1 and the bismuth-based adsorbents prepared in Examples 1 to 6 at 130°C;

[0032] Figure 7 The XRD patterns of the bismuth-based adsorbents prepared in Examples 5 and 6 before and after irradiation;

[0033] Figure 8 The BET spectra of the bismuth-based adsorbents prepared in Examples 5 and 6, wherein the left figure is the bismuth-based adsorbent prepared in Example 5, and the right figure is the bismuth-based adsorbent prepared in Example 6;

[0034] Figure 9 Schematic diagram of the synthesis mechanism of the bismuth-based adsorbent according to an embodiment of the present invention;

[0035] Figure 10 This is a graph showing the relationship between the amount of bismuth acetate used and the amount of iodine adsorbed by the adsorbent;

[0036] Figure 11 This is the relationship between the amount of tetraethyl silicate and the quality of the product. DETAILED DESCRIPTION

[0037] The present invention provides a method for preparing a bismuth-based adsorbent, comprising the following steps:

[0038] Adding homogeneous solution A dropwise to homogeneous solution B to obtain a homogeneous sol, wherein the homogeneous solution A comprises ethyl orthosilicate, persulfate and water, and the homogeneous solution B comprises bismuth salt, P123 and water;

[0039] The homogeneous sol is subjected to hydrothermal synthesis and then solid-liquid separation, and the obtained solid is washed, dried and calcined in sequence to obtain the bismuth-based adsorbent.

[0040] In the present invention, unless otherwise specified, the materials and equipment used are commercially available products in the art.

[0041] The present invention adds a homogeneous solution A dropwise into a homogeneous solution B to obtain a homogeneous sol, wherein the homogeneous solution A comprises ethyl orthosilicate, persulfate and water, and the homogeneous solution B comprises bismuth salt, P123 and water.

[0042] The present invention mixes ethyl orthosilicate, persulfate and water to obtain a homogeneous solution A.

[0043] In the present invention, the persulfate is preferably an alkali metal persulfate, more preferably sodium persulfate. The addition of the persulfate to the homogeneous solution A eliminates the need for a strong acid environment in the subsequent SBA-15 synthesis process.

[0044] In the present invention, the usage ratio of ethyl orthosilicate (tetraethyl silicate) and persulfate is preferably 4.6 mL (4.3 g): 0.0495-0.2 g, more preferably 4.6 mL: 0.0495 g.

[0045] The present invention preferably first mixes persulfate and water to obtain a persulfate aqueous solution, and then drops the ethyl orthosilicate into the persulfate aqueous solution; the concentration of the persulfate aqueous solution is preferably 3.3 g / L, and the volume ratio of the ethyl orthosilicate to the persulfate aqueous solution is preferably 4.6:15; the rate of addition is preferably 60 to 80 drops / min, more preferably 70 drops / min; the rate of addition can ensure the orderly structure of the SBA-15 and sufficient subsequent hydrothermal synthesis reaction. The present invention preferably further includes stirring after dropping the ethyl orthosilicate into the sodium persulfate aqueous solution, the stirring temperature is preferably 30 to 40° C., more preferably 35° C., and the stirring time is preferably 3 to 4 hours, so that the sodium persulfate and ethyl orthosilicate are evenly mixed in the solution.

[0046] The present invention mixes bismuth salt, P123 and water to obtain a homogeneous solution B.

[0047] In the present invention, the bismuth salt preferably includes one or more of bismuth acetate, bismuth nitrate and bismuth chloride, more preferably bismuth acetate.

[0048] In the present invention, the mass ratio of the bismuth salt to P123 is preferably 0.396-1.584:2, more preferably 0.396:2, 0.595:2, 0.792:2, 0.991:2, 1.189:2 or 1.584:2; the P123 is a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (PEO-PPO-PEO) with a weight-average molecular weight of 5800, and the P123 is a template.

[0049] The present invention preferably first mixes P123 and water to obtain a P123 aqueous solution, which is then mixed with the bismuth salt. The preparation method of the P123 aqueous solution preferably includes the following steps: dissolving P123 in deionized water and stirring until completely dissolved to obtain a P123 aqueous solution; the stirring temperature is preferably 35-40°C, the time is preferably 3-4 hours, and the concentration of the P123 aqueous solution is preferably 23.5g / L. The P123 aqueous solution and the bismuth salt are preferably mixed by stirring, and the stirring temperature is preferably 35-40°C. The present invention has no special requirements for the stirring time, as long as the P123 and the bismuth source (bismuth salt) are evenly mixed in the solution.

[0050] After obtaining the homogeneous solution A and the homogeneous solution B, the present invention adds the homogeneous solution A dropwise into the homogeneous solution B to obtain a homogeneous sol.

[0051] In the present invention, the dropping rate is preferably 60 to 80 drops / min, more preferably 70 drops / min. The dropping rate will affect the structure and morphology of the synthesized SBA-15. The dropping rate of the present invention can ensure that the SBA-15 structure is orderly.

[0052] In the present invention, the dosage ratio of ethyl orthosilicate, persulfate, P123 and bismuth acetate in the homogeneous sol is preferably 4.6 mL: 0.0495-0.2 g: 2 g: 0.396-1.584 g, more preferably 4.6 mL: 0.0495 g: 2 g: xg, where x is 0.595, 0.792, 0.991, 1.189 or 1.584.

[0053] In the present invention, the molar ratio of silicon in the tetraethyl orthosilicate to bismuth in the bismuth salt is preferably 6 to 30:1, more preferably 6.726:1.

[0054] In the present invention, the dropping step preferably includes stirring, the stirring temperature is preferably 35-40° C., the stirring time is preferably 24 h, and the homogeneous sol obtained after the stirring is a uniform mixed liquid.

[0055] After obtaining the homogeneous sol, the present invention performs hydrothermal synthesis on the homogeneous sol and then performs solid-liquid separation, and sequentially washes, dries and calcines the obtained solid to obtain the bismuth-based adsorbent.

[0056] In the present invention, the temperature of the hydrothermal synthesis is preferably 80 to 130° C., more preferably 100° C.; the time is preferably 12 to 48 hours, more preferably 24 hours. In a specific embodiment of the present invention, the hydrothermal synthesis is crystallization in a polytetrafluoroethylene reactor. The homogeneous sol of the present invention includes tetraethyl orthosilicate, persulfate, bismuth salt, P123 and water. The homogeneous sol is hydrothermally synthesized, tetraethyl orthosilicate is hydrolyzed, and molecular sieve SBA-15 is generated under the action of P123. No acid source is added, thereby realizing the preparation of bismuth-based iodine adsorbent under neutral conditions, which is more environmentally friendly. SBA-15 is prepared during the hydrothermal synthesis process, and the bismuth source is doped into the pore wall of the SBA-15 mesoporous material, realizing the "one-step" preparation of bismuth-based adsorbent, which is simple to operate and low in cost.

[0057] In the present invention, the washing preferably includes sequentially washing with deionized water and washing with ethanol. The washing with deionized water is preferably performed until there is no foam. The number of times of washing with deionized water and washing with ethanol is preferably 5 or more.

[0058] In the present invention, the drying temperature is preferably 40 to 100° C., more preferably 100° C.; the drying time is preferably 8 to 24 hours, more preferably 8 hours.

[0059] In the present invention, the calcination temperature is preferably 450-550° C., more preferably 500-550° C.; the calcination time is preferably 4-12 h, more preferably 6-10 h.

[0060] In the present invention, the calcination is preferably carried out in an argon-hydrogen mixed gas atmosphere, wherein the volume concentration of hydrogen in the argon-hydrogen mixed gas is preferably 3-5%, more preferably 4%. The hydrogen concentration described in the present invention has both a reducing effect and a protective effect. The calcination can burn off excess template and simultaneously reduce the bismuth salt to metallic bismuth, which is loaded on the surface of SBA-15.

[0061] The present invention also provides a bismuth-based adsorbent obtained by the preparation method described in the above technical solution, comprising SBA-15 and bismuth, wherein the bismuth is loaded on the surface of the SBA-15.

[0062] In the present invention, the Bi loading in the bismuth-based adsorbent is preferably 0-20 mol%, and is not 0, more preferably 4 mol%, 6 mol%, 8 mol%, 10 mol%, 12 mol%, 15 mol%, and more preferably 15 mol%.

[0063] In the present invention, the SBA-15 surface includes the surface inside the pore wall of the SBA-15 mesoporous material.

[0064] The present invention also provides the use of the bismuth-based adsorbent described in the above technical solution in adsorbing iodine.

[0065] In the present invention, the iodine is preferably iodine vapor. The present invention has no particular requirements for the method of adsorbing iodine vapor. The bismuth-based adsorbent can be placed in iodine vapor for adsorption. The adsorption temperature is preferably 130°C, and the adsorption time is preferably 6 hours. In a specific embodiment of the present invention, the bismuth-based adsorbent is placed in a small crucible. The small crucible containing the bismuth-based adsorbent is then placed in a large crucible containing iodine. The large crucible is then sealed and placed in a 130°C oven for adsorption.

[0066] In the present invention, the adsorption mechanism of iodine by the bismuth-based adsorbent is as follows: Bi loaded on the surface of SBA-15 reacts with iodine in the following manner:

[0067] 3I2+2Bi→2BiI3.

[0068] In the present invention, the mass ratio of the bismuth-based adsorbent to iodine is preferably 1:0.1-2.

[0069] To further illustrate the present invention, the bismuth-based adsorbent, its preparation method, and application are described in detail below with reference to the accompanying drawings and examples. However, these should not be construed as limiting the scope of protection of the present invention.

[0070] In a specific embodiment of the present invention, the preparation method of the sodium persulfate aqueous solution is as follows: 0.0495 g of sodium persulfate (Na2S2O8) is dissolved in 15 mL of deionized water to obtain a sodium persulfate aqueous solution with a concentration of 3.3 g / L.

[0071] In a specific embodiment of the present invention, the preparation method of the P123 aqueous solution is as follows: 2 g of P123 is dissolved in 85 mL of deionized water, and stirred at 35° C. for 3 h to obtain a P123 aqueous solution with a concentration of 23.5 g / L.

[0072] Comparative Example 1

[0073] 4.6 mL of ethyl orthosilicate was added dropwise to 15 mL of 3.3 g / L sodium persulfate aqueous solution and stirred at 35 °C for 3 h to obtain homogeneous solution A; 23.5 g / L of P123 aqueous solution was homogeneous solution B;

[0074] The homogeneous solution A was added dropwise to 85 mL of the homogeneous solution B at a rate of 70 drops / min, and stirred at 35°C for 24 hours to obtain a homogeneous sol; the homogeneous sol was placed in a polytetrafluoroethylene reactor and subjected to hydrothermal synthesis at 100°C for 24 hours;

[0075] The solid-liquid mixture after hydrothermal synthesis was filtered and washed five times with deionized water and ethanol respectively; the obtained solid was then dried in a drying cabinet at 100°C for 8 hours; and finally, calcined at 550°C in an argon-hydrogen atmosphere (hydrogen concentration of 4% by volume) for 6 hours to obtain a white powdery SBA-15 adsorbent (S101).

[0076] Example 1

[0077] 4.6 mL of ethyl orthosilicate was added dropwise to 15 mL of a 3.3 g / L sodium persulfate aqueous solution and stirred at 35°C for 3 h to obtain a homogeneous solution A. 0.396 g (denoted as m) of bismuth acetate was dissolved in 85 mL of a 23.5 g / L P123 aqueous solution and stirred at 35°C until completely dissolved to obtain a homogeneous solution B.

[0078] The homogeneous solution A was added dropwise to the homogeneous solution B at a rate of 70 drops / min, and stirred at 35°C for 24 hours to obtain a homogeneous sol; the homogeneous sol was placed in a polytetrafluoroethylene reactor and subjected to hydrothermal synthesis at 100°C for 24 hours;

[0079] The solid-liquid mixture after hydrothermal synthesis was filtered and washed five times with deionized water and ethanol respectively; the obtained solid was then dried in a drying cabinet at 100°C for 8 hours; finally, it was calcined at 550°C in an argon-hydrogen atmosphere (hydrogen volume concentration of 4%) for 6 hours to obtain a gray powdered Bi-SBA-15-1 adsorbent (S102).

[0080] Example 2

[0081] The only difference between this embodiment and embodiment 1 is the mass of bismuth acetate. In this embodiment, m is 0.595 g, and a gray powdery Bi-SBA-15-2 adsorbent (S103) is obtained.

[0082] Example 3

[0083] The only difference between this embodiment and embodiment 1 is the mass of bismuth acetate. In this embodiment, m is 0.792 g, and a gray powdery Bi-SBA-15-3 adsorbent (S104) is obtained.

[0084] Example 4

[0085] The only difference between this embodiment and embodiment 1 is the mass of bismuth acetate. In this embodiment, m is 0.991 g, and a gray powdery Bi-SBA-15-4 adsorbent (S105) is obtained.

[0086] Example 5

[0087] The only difference between this embodiment and embodiment 1 is the mass of bismuth acetate. In this embodiment, m is 1.189 g, and a gray powdery Bi-SBA-15-5 adsorbent (S106) is obtained.

[0088] Example 6

[0089] The only difference between this embodiment and embodiment 1 is the mass of bismuth acetate. In this embodiment, m is 1.584 g, and a gray powdery Bi-SBA-15-6 adsorbent (S107) is obtained.

[0090] The specific surface area of ​​the Bi-SBA-15-6 adsorbent of Example 6 was calculated using the BET method to be 566.25 m 2 ·g -1 The pore volume was calculated by the BJH method to be 1.033 cm 3 ·g -1 , the average pore diameter is 6.673nm.

[0091] Figure 1 This is a flow chart of a method for preparing an adsorbent according to an embodiment of the present invention. Ethyl orthosilicate is dropped into an aqueous sodium persulfate solution and stirred to obtain a homogeneous solution A. Bismuth acetate is dissolved in an aqueous P123 solution to form a homogeneous solution B. Homogeneous solution A is added dropwise to homogeneous solution B and stirred to obtain a homogeneous sol. The obtained homogeneous sol is subjected to hydrothermal synthesis. The solid-liquid mixture after the hydrothermal synthesis is filtered, washed, dried, and calcined in a 4% argon-hydrogen atmosphere to obtain an adsorbent.

[0092] Figure 2 The top row shows the product after drying and before calcination. The top row shows the product after calcination. The top row shows the product after calcination. The top row shows the product after calcination. The bismuth-based adsorbents prepared in Examples 1 to 6 are converted to gray (dark gray or nearly black), indicating that bismuth is successfully loaded.

[0093] Figure 3 The XRD patterns of the adsorbent of Comparative Example 1 and the bismuth-based adsorbents of Examples 1 to 6 are as follows: S101, S102, S103, S104, and S105 have two obvious small-angle diffraction peaks in the range of 1.4 to 1.8, indicating that the obtained samples have a mesoporous structure. Figure 3 It can be seen that with Bi 3+ As the addition amount gradually increases, the small-angle diffraction peak of modified SBA-15 (Bi-SBA-15) gradually moves to the high-angle direction until it disappears. This may be because as Bi 3+ Increasing the addition amount destroyed the orderly pore formation during the synthesis process.

[0094] Figure 4 The XRD patterns of the adsorbent of Comparative Example 1 and the bismuth-based adsorbents of Examples 1 to 6 indicate that bismuth was successfully loaded onto the surface of SBA-15.

[0095] Application Example 1

[0096] The bismuth-based adsorbents of Examples 1 to 6 and the adsorbent of Comparative Example 1 were subjected to iodine adsorption tests, respectively. The specific methods are as follows:

[0097] Weigh m1g of adsorbent (SBA-15 or Bi-SBA-15-1~6) and place it in a small crucible. Then place the small crucible in a large crucible containing 2g of iodine. Then seal the large crucible and place it in a 130℃ oven for 6h. After cooling, weigh the mass of the adsorbent material after iodine absorption, record it as m2g, and calculate its adsorption capacity Q according to the following formula:

[0098]

[0099] The bismuth-based adsorbents prepared in Examples 1 to 6 were subjected to XRD analysis after iodine adsorption. The results were as follows: Figure 5 As shown. Figure 5 It can be seen that iodine becomes stable BiI3 after being adsorbed by the bismuth-based adsorbent, which is a stable substance.

[0100] The adsorption results of iodine vapor by the bismuth-based adsorbents of Examples 1 to 6 and the adsorbent of Comparative Example 1 at 130°C are as follows: Figure 6 and as shown in Table 1.

[0101] Table 1 Iodine adsorption capacity of the adsorbents of Examples 1 to 6 and Comparative Example 1

[0102]

[0103] As can be seen from Table 1, the adsorption capacity of iodine vapor by the bismuth-based adsorbent of the present invention ranges from 245.9 to 625.5 mg / g, and the adsorption capacity of iodine is high.

[0104] Figure 7 The XRD patterns of the bismuth-based adsorbents prepared in Examples 5 and 6 before and after 600 kGy γ-irradiation are shown. The XRD diffraction peaks of the bismuth-based adsorbent materials do not change before and after γ-irradiation, indicating that the bismuth-based adsorbent materials prepared in the present invention have good irradiation stability.

[0105] Figure 8 These are the BET spectra of the bismuth-based adsorbents prepared in Examples 5 and 6, where the left figure is the bismuth-based adsorbent prepared in Example 5, and the right figure is the bismuth-based adsorbent prepared in Example 6. The bismuth-based adsorbent material is a porous material with a large specific surface area.

[0106] Figure 9 Schematic diagram of the synthesis mechanism of the bismuth-based adsorbent according to an embodiment of the present invention, wherein a homogeneous sol is prepared into a Bi-SBA-15 adsorbent material in one step through hydrothermal synthesis.

[0107] Example 7

[0108] The difference between this embodiment and embodiment 6 is that the mass of bismuth acetate is different. The mass of bismuth acetate is 1.792, 1.947, 2.203 and 2.394 g, respectively. The prepared adsorbent materials are subjected to iodine adsorption tests using the method of application example 1. The maximum adsorption capacity of iodine vapor is 624.7, 626.2, 621.4 and 627.9 mg / g, respectively. Figure 10 shown.

[0109] Example 8

[0110] The maximum adsorption capacity of the material obtained by replacing the bismuth acetate in Example 6 with an equal molar amount of bismuth nitrate for iodine vapor is 569.2 mg / g, and the maximum adsorption capacity of the material obtained by replacing it with bismuth chloride for iodine vapor is 483.6 mg / g. The iodine adsorption test method is the same as that in Application Example 1.

[0111] Example 9

[0112] The difference between this embodiment and embodiment 6 is that the amount of ethyl orthosilicate used is different. The amount of ethyl orthosilicate used is set to 4.8 mL and 5 mL respectively, and the mass of the obtained products is 1.511 g and 1.509 g respectively. Figure 11 shown.

[0113] Comparative Example 2

[0114] The difference between this comparative example and Example 6 is that the bismuth salt is replaced with bismuth acetate and titanium tetrachloride in equal molar amounts (molar ratio of 4:3). The prepared adsorbent material is tested for iodine adsorption using the method of Application Example 1. The maximum iodine adsorption capacity is 23.61 mg / g, and the iodine adsorption performance is much lower than that of the Bi-based adsorbent material of the present invention.

[0115] Although the above embodiments provide a detailed description of the present invention, they are only part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on the embodiments of the present invention without creative work, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a bismuth-based adsorbent, characterized in that: The steps are: Homogeneous solution A is added dropwise to homogeneous solution B to obtain a homogeneous sol, wherein the homogeneous solution A comprises ethyl orthosilicate, persulfate, and water, and the homogeneous solution B comprises bismuth salt, P123, and water; the bismuth salt is bismuth acetate; and the mass ratio of the bismuth salt to P123 is 1.584:2; The homogeneous sol is hydrothermally synthesized and then solid-liquid separated, and the obtained solid is washed, dried and calcined in sequence to obtain the bismuth-based adsorbent; The bismuth-based adsorbent consists of SBA-15 and loaded elemental bismuth.

2. The preparation method according to claim 1, characterized in that The usage ratio of the ethyl orthosilicate and the persulfate is 4.6 mL: 0.0495-0.2 g.

3. The preparation method according to claim 1, characterized in that The dropping rate is 60-80 drops / min.

4. The preparation method according to claim 1 or 2, characterized in that The temperature of the hydrothermal synthesis is 80-130° C., and the time is 12-48 hours.

5. The preparation method according to claim 1, characterized in that The drying temperature is 40-100° C. and the drying time is 8-24 hours.

6. The preparation method according to claim 1, characterized in that The calcination temperature is 450-550° C. and the calcination time is 4-12 hours.

7. The preparation method according to claim 1 or 6, characterized in that The calcination is carried out in an argon-hydrogen mixed gas atmosphere, wherein the volume concentration of hydrogen in the argon-hydrogen mixed gas is 3-5%.

8. The bismuth-based adsorbent obtained by the preparation method according to any one of claims 1 to 7, characterized in that: The invention comprises SBA-15 and bismuth, wherein the bismuth is loaded on the surface of the SBA-15.

9. Use of the bismuth-based adsorbent according to claim 8 in adsorbing iodine.

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