A composite aerogel of adsorbing Cs + , Sr 2+ in water and a preparation method thereof

Abstract

The application discloses a composite aerogel for adsorbing Cs + , Sr 2+ in wastewater and a preparation method thereof. The MoS2@SA aerogel is obtained by mixing molybdenum disulfide (MoS2) nanosheets and sodium alginate (SA), cross-linking with calcium chloride and freeze-drying; the ZIF-8 / MoS2@SA aerogel is obtained by sequentially immersing the MoS2@SA aerogel into a solution containing zinc acetate dihydrate and 2-methyl imidazole and then cyclically growing ZIF-8; and the KMg@ZIF-8 / MoS2@SA aerogel is obtained by sequentially immersing the ZIF-8 / MoS2@SA aerogel into a solution containing potassium ferrocyanide and magnesium chloride and then growing potassium ferrous hydroxide magnesium. The composite aerogel can effectively adsorb heavy metal ions Cs and Sr in water and is widely used in wastewater treatment processes discharged by research institutes, factories and the like.

Description

Technical Field

[0001] The present invention belongs to the field of water treatment adsorption materials, and specifically relates to a method for adsorbing Cs in wastewater. + 、Sr 2+ Preparation method of composite aerogel, Background Art

[0002] With the rapid increase in population and rapid industrial development, global energy demand has exploded. Nuclear power has become one of the most important resources for coping with energy shortages. However, nuclear energy safety has always been a challenging issue. Although the discharged nuclear wastewater has been treated, according to the report of the International Atomic Energy Agency, 10 radioactive isotopes ( 3 H. 14 C. 134 Cs, 137 Cs, 60 Co、 125 Sb, 106 Such as 90 Sr. 99 Tc, 129 I). Among these radionuclides, 137 Cs and 90 Sr is one of the most harmful radioactive elements, causing serious pollution and damage to the environment and threatening human life. 137 Cs and 90 The half-lives of Sr are both very long, 30.12 years and 28.79 years respectively, which will damage the environment over a long period of time. 137 Cs is usually Cs + exists in the form of 90 Sr is usually expressed as Sr 2+ It exists in the form of ions, which can quickly migrate into the food chain due to its high water solubility and high environmental mobility. + With K + 、Na + have similar chemical properties, and Sr 2+ With Ca 2+ Because they have similar chemical properties, they can be easily assimilated by terrestrial and aquatic organisms and then enter the human food chain, where they are easily absorbed by the body, causing cell damage or death and soft tissue cancers such as thyroid cancer. Therefore, it is necessary to develop effective methods to remove them from aqueous nuclear waste. 137 Cs and 90 Sr. is crucial.

[0003] Molybdenum disulfide (MoS2) is a graphene-like two-dimensional transition metal sulfide with a unique three-layer stacked atomic layer (S-Mo-S) sandwich structure and excellent chemical stability and structural designability. In addition, the abundant sulfur groups on the surface and edges of MoS2 give it good adsorption properties for heavy metal elements. Therefore, in recent years, MoS2 has become an ideal material for adsorption and reduction removal of heavy metal elements in wastewater. + The capacity of Cs2 has been greatly improved by researchers at home and abroad. However, these composite modified nano-MoS2 can + There are also disadvantages such as low removal capacity and slow removal rate. Therefore, how to improve the treatment of Cs by MoS2 + The removal capacity and removal rate of heavy metal wastewater pollution remain extremely challenging research topics.

[0004] 2-Methylimidazole zinc salt ZIF-8 is composed of metal ions (Zn 2+ ) and an organic ligand (2-methylimidazole), and was first designed, synthesized, and reported by the research group of Academician Chen Xiaoming at Sun Yat-sen University. ZIF-8 is the most thoroughly studied ZIFs material and the most widely used ZIFs material. In the crystal structure of ZIF-8, polyhedra represent Zn, spheres represent N, and lines represent C. It has a sod-type topology and is composed of 1.16 nm nanocages connected by six-membered windows of 0.34 nm in size. ZIF-8 has many characteristics such as high thermal stability, high chemical stability, high controllability, high pore volume, and high hydrophobicity, and has been widely used in many fields.

[0005] Metal ferrocyanide mainly refers to transition metal (Fe, Co, Ni, Cu, Zn) ferrocyanide, the chemical formula is A a M b [Fe(CN)6] c , where A represents a monovalent cation such as Cs or K, and M represents a transition metal ion. Metal ferrocyanide is a class of substances with an octahedral central cubic structure, in which the metallic iron ions are connected by CΞN bonds and alternately form a three-dimensional network aggregate structure at the nodes of the central cubic lattice. The monovalent cations fill the gaps in the cubic lattice to provide charge compensation. Ferrocyanide has zeolite properties and can react with K in aqueous solution. + 、Na + Plasma exchange is fast, and the affinity for metal ions is: Cs + >Rb + >NH 4+ >K + >Na + >Li + Based on this, ferrocyanide is often used as an ion exchanger to treat Cs-containing+ Furthermore, the transition metals in ferrocyanide are typically nickel, cobalt, copper, and zinc, which often increase production costs. Replacing these transition metals with inexpensive metals is often the best solution. Summary of the Invention

[0006] The present invention aims to provide a method for adsorbing Cs in wastewater. + 、Sr 2+ Composite aerogel and preparation method thereof. The present invention first synthesizes MoS2@SA aerogel and then cyclically grows ZIF-8 and potassium magnesium ferrocyanide on the surface to obtain KMg@ZIF-8 / MoS2@SA aerogel, which is used to adsorb metal ions Cs and Sr in water and has broad application prospects.

[0007] The present invention first provides a method for adsorbing Cs in water. + 、Sr 2+ The preparation method of the composite aerogel comprises the following steps:

[0008] (1) The MoS2 dispersion and sodium alginate (SA) solution were mixed evenly to obtain a mixed solution, the mixed solution was freeze-dried and then taken out, calcium chloride solution was added for cross-linking reaction, and MoS2@SA aerogel was obtained after washing and drying;

[0009] (2) The MoS2@SA aerogel was sequentially immersed in a soluble zinc salt aqueous solution and a 2-methylimidazole aqueous solution for one growth cycle, and then freeze-dried; after being taken out, the growth cycle was repeated to obtain ZIF-8 / MoS2@SA aerogel;

[0010] Specifically, the MoS2@SA aerogel is first immersed in a soluble zinc salt aqueous solution for 3 to 6 hours, and then immersed in a 2-methylimidazole aqueous solution for 3 to 6 hours, and a growth cycle is performed. The aerogel that has grown ZIF-8 once is taken out and the above steps are repeated. The aerogel is freeze-dried for 24 to 72 hours to obtain ZIF-8 / MoS2@SA aerogel. The growth steps are three times in total, and the cycle time is 6 to 12 hours. The MoS2@SA aerogel fully reacts in the soluble zinc salt and 2-methylimidazole solution to generate small spherical particles with smooth surfaces and clear boundaries. In practical applications, Zn is achieved by breaking the Zn-O in ZIF-8. 2+ Select Exchange Sr 2+ Selective adsorption effect.

[0011] (3) The ZIF-8 / MoS2@SA aerogel was immersed in potassium ferrocyanide aqueous solution and magnesium chloride aqueous solution in turn and freeze-dried to obtain potassium ferrocyanide-loaded magnesium aerogel, which was labeled as KMg@ZIF-8 / MoS2@SA aerogel.

[0012] Specifically, the ZIF-8 / MoS2@SA aerogel was first immersed in an aqueous solution of potassium ferrocyanide for 3-6 hours, and then immersed in an aqueous solution of magnesium chloride for 3-6 hours to grow. The product was removed, washed with pure water, and freeze-dried for 24-72 hours to uniformly grow potassium ferrocyanide and magnesium ferrocyanide on the surface of the ZIF-8 / MoS2@SA aerogel.

[0013] In the above technical solution, preferably, the mass ratio of MoS2 and SA is 1:1, and the concentration of sodium alginate in the mixed solution is 5~10 mg / mL.

[0014] Preferably, the MoS2 dispersion and SA solution in step (1) are mixed by stirring first and then ultrasonic mixing at a temperature of 30-50°C, a rotation speed of 300-500 r / min, and a mixing time of 0.5-2 h.

[0015] Preferably, the concentration of the calcium chloride solution in step (1) is 0.1-1 mol / L.

[0016] Preferably, the MoS2 described in step (1) is MoS2 nanosheets, which are prepared by the following method: dissolving or dispersing ammonium molybdate and thiourea in water, stirring and mixing uniformly, hydrothermally reacting at 180-220°C for 24-48 hours, naturally cooling to room temperature, washing with deionized water and ethanol, and freeze-drying to obtain MoS2 nanosheets; wherein the molar ratio of thiourea to molybdenum ions in ammonium molybdate is 1:4-5.

[0017] Preferably, the freeze-drying temperature in step (1) is -50 to -60°C, and the freezing time is 24 to 72 hours.

[0018] Preferably, the molar ratio of the soluble zinc salt to 2-methylimidazole in step (2) is 1:8-9; the concentration of the soluble zinc salt aqueous solution is 0.09-0.1 mol / L; and the volume ratio of the soluble zinc salt aqueous solution to the 2-methylimidazole aqueous solution is 1:1.

[0019] Preferably, the immersion time in step (2) is 3 to 6 hours; and the total number of repeated growth cycles is more than three times.

[0020] Preferably, the concentration of the potassium ferrocyanide aqueous solution in step (3) is 0.5-1.5 mol / L; the concentration of the magnesium chloride aqueous solution is 1-3 mol / L.

[0021] Preferably, the immersion time in step (3) is 3 to 6 hours; the freeze-drying temperature is -50 to -60°C, and the freezing time is 24 to 72 hours.

[0022] The application further provides the composite aerogel prepared by the method.

[0023] The application further provides application of the composite aerogel prepared by the method in adsorbing Cs + and Sr 2+ in water.

[0024] In one specific embodiment of the application, 20 mg of KMg@ZIF-8 / MoS2@SA aerogel is added to a system of 20 mL of a solution with a Cs + and Sr 2+ concentration of 100 mg / L, and after oscillation adsorption in a constant-temperature shaker at 220 r / min for 24 h, the removal rate of Cs + and Sr 2+ in the wastewater can reach 98.9% and 99.8%, respectively, and the purpose of purifying Cs + and Sr 2+ in the wastewater can be achieved by simple drying and separation after adsorption of the composite aerogel.

[0025] The application synthesizes MoS2 by a simple hydrothermal method, and then MoS2 and SA are crosslinked by calcium chloride to prepare MoS2@SA aerogel, and ZIF-8 is grown on the surface under the condition that Mo-S and C=O bonds gradually appear in the XPS spectrum of the aerogel, and after the successful construction of Zn-O bonds, KMg@ZIF-8 / MoS2@SA aerogel is obtained by growing potassium ferrocyanide magnesium on the surface. The KMg@ZIF-8 / MoS2@SA aerogel is used for selectively removing radioactive elements Cs and Sr in water, and can be used again by simple drying and separation, thereby saving energy and protecting the environment.

[0026] The application has the following beneficial effects:

[0027] (1) The KMg@ZIF-8 / MoS2@SA aerogel provided by the application uses SA as a carrier, loads MoS2, and grows ZIF-8, and finally grows potassium ferrocyanide magnesium with selective adsorption performance for Cs + and Sr 2+ , and Mg 2+ has strong selectivity for Sr 2+ , thereby realizing efficient purification of Cs and Sr ions, and compared with a traditional industrial method for separating Cs and Sr, the method has low energy consumption, high selective separation efficiency, can perform one-step solidification separation, has no secondary pollution, effectively avoids the shortcomings of redundant separation operation and large amount of waste liquid in the traditional method, and the composite KMg@ZIF-8 / MoS2@SA aerogel can efficiently adsorb Cs + and Sr 2+ in wastewater, and the adsorption efficiency is as high as 98.9% and 99.8%, respectively.

[0028] (2) Using composite aerogel to adsorb Cs in water + 、Sr 2+ Afterwards, it can be effectively separated from the reaction system through simple drying and separation technology without secondary pollution;

[0029] (3) The composite aerogel provided by the present invention has a strong effect on the Cs in pure water, tap water and seawater. + 、Sr 2+ Both have good adsorption and removal effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 SEM image of KMg@ZIF-8 / MoS2@SA aerogel;

[0031] Figure 2 XRD patterns of KMg@ZIF-8 / MoS2@SA aerogel and comparative materials;

[0032] Figure 3 TGA graphs of KMg@ZIF-8 / MoS2@SA aerogel and comparative materials;

[0033] Figure 4 This is the real water sample adsorption diagram of KMg@ZIF-8 / MoS2@SA aerogel;

[0034] Figure 5 This is the recycling diagram of KMg@ZIF-8 / MoS2@SA aerogel. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Example 1

[0036] (1) MoS2 nanosheets were synthesized by a simple hydrothermal method. 2.498 g of ammonium molybdate ((NH4)6Mo7O2·4H2O) and 4.606 g of thiourea (CH4N2S) were dissolved in 70 mL of deionized water and stirred vigorously for 30 min. The mixed solution was then transferred to a 100 mL reactor and heated to 220°C for 24 h. After cooling naturally to room temperature, the black product was rinsed several times with deionized water and ethanol and freeze-dried using a freeze dryer (-55°C for 72 h) to obtain MoS2 nanosheets.

[0037] Take 50 mL of 20 mg / mL MoS2 dispersion, add 50 mL of 20 mg / mL sodium alginate solution, stir at 300 r / min at 40℃ for 10 min, and ultrasonically react for 30 min. The obtained product is freeze-dried (-55℃, 24 h) and then taken out. 0.1 mol / L calcium chloride solution is added for cross-linking. After alternately washing with ethanol and pure water, it is freeze-dried (-55℃, 72 h) to obtain MoS2@SA aerogel.

[0038] (2) The MoS2@SA aerogel was taken out and immersed in 0.432 g of zinc acetate dihydrate dissolved in 20 mL of aqueous solution for 3 h, and then immersed in 1.324 g of 2-methylimidazole dissolved in 20 mL of aqueous solution for 3 h for growth, and freeze-dried (-55°C, 72 h) to obtain ZIF-8 / MoS2@SA aerogel.

[0039] (3) Take the ZIF-8 / MoS2@SA aerogel and soak it in 4.2239 g of potassium ferrocyanide dissolved in 20 mL of aqueous solution (to ensure that the concentration of the prepared solution is 0.5 mol / L) for 3 h, and then soak it in 2.033 g of magnesium chloride dissolved in 20 mL of aqueous solution for 3 h for growth. Then freeze-dry (-55℃, 72 h) to obtain KMg@ZIF-8 / MoS2@SA aerogel.

[0040] Take 20 mg of the composite aerogel prepared in Example 1 and add it into the system with 20 mL of Cs + 、Sr 2+ The concentration of Cs in the wastewater was 100 mg / L and the solution was placed in a constant temperature shaker at 220 r / min for 24 h. + 、Sr 2+ The removal rates can reach 98.9% and 99.8% respectively. After adsorption, the composite aerogel can be separated by simple drying to achieve the adsorption of Cs in water. + 、Sr 2+ purpose. Example 2

[0041] (1) As in Example 1, MoS2 nanosheets were synthesized using a simple hydrothermal method. 25 mL of 20 mg / mL MoS2 dispersion was added to 25 mL of 20 mg / mL sodium alginate solution of equal mass. The mixture was stirred at 300 r / min at 40°C for 10 min and ultrasonically reacted for 30 min. The obtained product was freeze-dried (-55°C, 24 h) and then taken out. 0.5 mol / L calcium chloride solution was added for cross-linking. The product was alternately washed with ethanol and pure water and then freeze-dried (-55°C, 72 h) to obtain MoS2@SA aerogel.

[0042] (2) The MoS2@SA aerogel was taken out and immersed in 0.216 g of zinc acetate dihydrate dissolved in 10 mL of aqueous solution for 3 h, and then immersed in 0.662 g of 2-methylimidazole dissolved in 10 mL of aqueous solution for 3 h for growth, and freeze-dried (-55°C, 72 h) to obtain ZIF-8 / MoS2@SA aerogel.

[0043] (3) Take the ZIF-8 / MoS2@SA aerogel and soak it in 4.2239 g of potassium ferrocyanide dissolved in 20 mL of aqueous solution (to ensure that the concentration of the prepared solution is 0.5 mol / L) for 3 h, and then soak it in 2.033 g of magnesium chloride dissolved in 20 mL of aqueous solution for 3 h for growth. Then freeze-dry (-55℃, 72 h) to obtain KMg@ZIF-8 / MoS2@SA aerogel.

[0044] Take 20 mg of the composite aerogel prepared in Example 2 and add it into the system with 20 mL of Cs + 、Sr 2+ The concentration of the solution was 100 mg / mL, and the adsorption was carried out in a constant temperature shaker at 220 r / min for 24 h. The Cs in the wastewater was detected. + 、Sr 2+ The removal rates can reach 95.1% and 96.7% respectively. Example 3

[0045] (1) As in Example 1, MoS2 nanosheets were synthesized using a simple hydrothermal method. 50 mL of 10 mg / mL MoS2 dispersion was added to 50 mL of 10 mg / mL sodium alginate solution. The mixture was stirred at 300 r / min at 40°C for 10 min and ultrasonically reacted for 30 min. The obtained product was freeze-dried (-55°C, 24 h) and then taken out. 0.1 mol / L calcium chloride solution was added for cross-linking. The product was washed alternately with ethanol and pure water and then freeze-dried (-55°C, 72 h) to obtain MoS2@SA aerogel.

[0046] (2) The MoS2@SA aerogel was taken out and immersed in 0.864 g of zinc acetate dihydrate dissolved in 40 mL of aqueous solution for 3 h, and then immersed in 2.648 g of 2-methylimidazole dissolved in 40 mL of aqueous solution for 3 h for growth, and freeze-dried (-55°C, 72 h) to obtain ZIF-8 / MoS2@SA aerogel.

[0047] (3) Take ZIF-8 / MoS2@SA aerogel and soak it in 4.2239 g potassium ferrocyanide (0.01 mol) dissolved in 10 mL aqueous solution (to ensure the concentration of the prepared solution is 1 mol / L) for 3 h, and then soak it in 2.033 g magnesium chloride (0.02 mol) dissolved in 10 mL aqueous solution for 3 h. Then grow it and freeze-dry it (-55℃, 72 h) to obtain KMg@ZIF-8 / MoS2@SA aerogel.

[0048] Take 20 mg of the composite aerogel prepared in Example 3 and add it into the system with 20 mL of Cs + 、Sr 2+ The concentration of the solution was 100 mg / mL, and the adsorption was carried out in a constant temperature shaker at 220 r / min for 24 h. The Cs in the wastewater was detected. + 、Sr 2+ The removal rates can reach 92.8% and 94.4%.

[0049] Comparative Example 1:

[0050] MoS2@SA aerogel was prepared in the same manner as in Example 1. + 、Sr 2+ The removal rates can reach 72.8% and 53.7% respectively.

[0051] Comparative Example 2:

[0052] The same method as in Example 1 was used to prepare ZIF-8 / MoS2@SA aerogel. + 、Sr 2+ The removal rates can reach 81.3% and 68.7% respectively.

[0053] Comparative Example 3:

[0054] The difference from Example 1 is that in step (3), ferric chloride is used instead of magnesium chloride, and the concentration of the ferric chloride solution is 2 mol / L, to obtain KFe@ZIF-8 / MoS2@SA aerogel. + 、Sr 2+ The removal rates were 92.8% and 70.2% respectively.

[0055] The KMg@ZIF-8 / MoS2@SA aerogel prepared in Example 1 was characterized and analyzed as follows:

[0056] Figure 1This is a SEM image of the KMg@ZIF-8 / MoS2@SA aerogel. The material was characterized using a Hitachi SU8020 scanning electron microscope. Sample preparation: 5 mg of sample was dispersed in 10 mL of anhydrous ethanol and sonicated for 0.5 h. After drying, the sample was adhered to a copper plate with conductive adhesive and gold-sprayed for measurement and analysis of the surface micromorphology. The flower-like layered structure of MoS2 can be observed, with small, angular, and spherical particles, characteristic of ZIF-8, appearing within the layers. This not only increases the specific surface area of ​​the adsorbent but also creates numerous functional groups and adsorption sites, providing a foundation for the aerogel's selective heavy metal adsorption performance.

[0057] Figure 2 The XRD patterns of the KMg@ZIF-8 / MoS2@SA aerogel and a comparative material were obtained using a DX-2700 X-ray diffractometer from Shanghai Precision Instruments Co., Ltd. Sample preparation: An appropriate amount of sample was prepared for diffractometry. Measurements were performed using a Cu target, an operating voltage of 35 kV, a current of 25 mA, and a scan step of 0.02° over a scanning range of 5° to 80°, with data collected every 0.5 seconds. The crystal structure of the material was analyzed. The figure shows distinct characteristic peaks at 2θ = 14.9°, 15.5°, 17.6°, 24.9°, 35.8°, 44.7°, and 51.3° for the KMg@ZIF-8 / MoS2@SA aerogel, indicating the successful growth of potassium magnesium ferrocyanide on the ZIF-8 / MoS2@SA aerogel surface. These diffraction peaks are consistent with those reported in the literature.

[0058] Figure 3 The TGA graphs of KMg@ZIF-8 / MoS2@SA aerogel and a comparative material were obtained using a TG-209-F3 thermogravimeter from NETZSCH, Germany. Sample preparation: An appropriate amount of sample (2-3 mg) was placed in the autosampler tray and heated at a rate of 10°C / min to 800°C in air. Data was collected and analyzed for the high-temperature resistance of the material. The graph shows that the mass loss of the KMg@ZIF-8 / MoS2@SA aerogel can be divided into three stages: the first stage is caused by the evaporation of water or residual methanol adsorbed in the adsorbent cavities or on the surface of the material; the second stage is a more rapid weight loss due to the collapse and thermal decomposition of the adsorbent material structure; and the third stage is caused by further structural decomposition within the material. After heating at 800°C, the KMg@ZIF-8 / MoS2@SA aerogel exhibits three stages of mass loss, yet the remaining mass remains as high as 71.4701% of its original mass, demonstrating excellent high-temperature resistance.

[0059] Figure 4This is the adsorption diagram of real water sample of KMg@ZIF-8 / MoS2@SA aerogel. The flame atomic absorption spectrometer of Jinan Jiedao Analytical Instrument Co., Ltd. was used. The actual water sample of the present invention was collected from the Yellow Sea. Sample preparation: To prepare the adsorption solution, the actual water sample was mixed with Cs + 、Sr 2+ The solution was mixed to reach 100 mg / L Cs at pH 6 and temperature 293 K. + 、Sr 2+ Concentration. Take the sample supernatant after adsorption and filter it using a 0.22 µm filter membrane, dilute it proportionally to within 0~10 mg / L and then place it into the instrument for testing. Figure 4 It can be seen that the aerogel has a strong effect on the Cs + 、Sr 2+ The adsorption law is the same as that of the tap water. The adsorption capacity is shown as pure water > tap water > Yellow Sea water. The reason is that there are many common positive-valent metal ions in the tap water environment, such as K + , Ca 2+ 、Na + Mg 2+ The ionic radius of these ions is small, which makes it easy for the adsorbent to undergo ion exchange reaction and occupy adsorption sites, resulting in a decrease in its adsorption efficiency in tap water. In seawater, there are not only more types and quantities of positively charged metal ions, but also the pH is often kept at an alkaline level, which makes KMg@ZIF-8 / MoS2@SA aerogel more effective in adsorbing Cs + 、Sr 2 + There will be OH - precipitation, thus affecting the adsorption efficiency of aerogel.

[0060] Figure 5 Figure 2 shows the recycling of KMg@ZIF-8 / MoS2@SA aerogel. The results were obtained using a flame atomic absorption spectrometer from Jinan Jiedao Analytical Instrument Co., Ltd. Sample preparation: 20 mg of KMg@ZIF-8 / MoS2@SA aerogel was added to a solution containing 100 mg / L Cs + 、Sr 2+ The solution was placed in a conical flask and allowed to stand for 24 h. The aerogels were then eluted with 20 mL of 1 mol / L hydrochloric acid to study their cycling performance. The eluted KMg@ZIF-8 / MoS2@SA aerogels were dried in an oven for 24 h and then used again for Cs + 、Sr 2+ The adsorption experiment was carried out on the solution. The process was repeated five times, and the supernatant of the sample after adsorption was taken and filtered using a 0.22 µm filter membrane. The sample was diluted proportionally to within 0-10 mg / L and then placed in the instrument for testing. Figure 5It can be seen that KMg@ZIF-8 / MoS2@SA aerogel still maintains excellent adsorption capacity (Cs + Reaching 48.19 mg / g, Sr 2+ reached 85.21 mg / g), Cs + 、Sr 2+ The adsorption efficiency remains above 90%, proving that KMg@ZIF-8 / MoS2@SA aerogel has good recycling capacity.

[0061] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for adsorbing Cs in water + 、Sr 2+ The method for preparing a composite aerogel is characterized in that: The steps include: (1) The MoS2 dispersion and the sodium alginate solution were mixed evenly to obtain a mixed solution, the mixed solution was freeze-dried and then taken out, calcium chloride solution was added for cross-linking reaction, and the MoS2@SA aerogel was obtained after washing and drying; (2) The MoS2@SA aerogel was sequentially immersed in a soluble zinc salt aqueous solution and a 2-methylimidazole aqueous solution for one growth cycle, and then freeze-dried; after being taken out, the growth cycle was repeated to obtain ZIF-8 / MoS2@SA aerogel; (3) The ZIF-8 / MoS2@SA aerogel was immersed in potassium ferrocyanide aqueous solution and magnesium chloride aqueous solution in sequence for full reaction, and then freeze-dried to obtain KMg@ZIF-8 / MoS2@SA aerogel.

2. The adsorption of Cs in water according to claim 1 + 、Sr 2+ The method for preparing a composite aerogel is characterized in that: The mass ratio of MoS2 and sodium alginate in step (1) is 1:1, and the concentration of sodium alginate in the mixed solution is 5-10 mg / mL; and / or the concentration of the calcium chloride solution is 0.1-1 mol / L.

3. The adsorption of Cs in water according to claim 1 + 、Sr 2+ The method for preparing a composite aerogel is characterized in that: The MoS2 described in step (1) is MoS2 nanosheets, which are prepared by the following method: dissolving or dispersing ammonium molybdate and thiourea in water, stirring and mixing uniformly, hydrothermally reacting at 180-220°C for 24-48 hours, naturally cooling to room temperature, washing, and freeze-drying to obtain MoS2 nanosheets; wherein the molar ratio of molybdenum ions to thiourea in ammonium molybdate is 1:4-5.

4. The adsorption of Cs in water according to claim 1 + 、Sr 2+ The method for preparing a composite aerogel is characterized in that: The molar ratio of the soluble zinc salt to 2-methylimidazole in step (2) is 1:8-9; the concentration of the soluble zinc salt aqueous solution is 0.09-0.1 mol / L; and the volume ratio of the soluble zinc salt aqueous solution to the 2-methylimidazole aqueous solution is 1:

1.

5. The adsorption of Cs in water according to claim 1 + 、Sr 2+ The method for preparing a composite aerogel is characterized in that: The concentration of the potassium ferrocyanide aqueous solution in step (3) is 0.5-1.5 mol / L; the concentration of the magnesium chloride aqueous solution is 1-3 mol / L.

6. The adsorption of Cs in water according to claim 1 + 、Sr 2+ The method for preparing a composite aerogel is characterized in that: The immersion time in step (2) is 3 to 6 hours; the total number of repeated growth cycles is more than three times; and / or the immersion time in step (3) is 3 to 6 hours.

7. The adsorption of Cs in water according to claim 1 + 、Sr 2+ The method for preparing a composite aerogel is characterized in that: The freeze-drying temperature is -50 to -60°C, and the freezing time is 24 to 72 hours.

8. The composite aerogel prepared by the method according to any one of claims 1 to 7.

9. The composite aerogel according to claim 8 absorbs Cs in water + 、Sr 2+ Application in.

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