Sodium manganate mesoporous silicate composite material for adsorbing cesium ions in radioactive wastewater as well as preparation method and application of sodium manganate mesoporous silicate composite material

Abstract

The invention discloses a sodium manganate mesoporous silicate composite material for adsorbing cesium ions in radioactive wastewater as well as a preparation method and application thereof, and relates to the field of radioactive wastewater treatment.The sodium manganate mesoporous silicate composite material is prepared by dissolving NaMoO4.H2O and CSN2H4 in deionized water respectively, stirring, carrying out a hydrothermal reaction, washing, drying and carrying out electron beam irradiation to obtain ball-flower-shaped MoS2; the preparation method comprises the following steps: dissolving sodium manganate / MoS2 in deionized water, dissolving flower-ball-shaped MoS2 and Na2SiO3. 9H2O in deionized water, carrying out ultrasonic treatment, dissolving (CH3COO) 2Mn. 4H2O in deionized water, mixing, stirring, carrying out a hydrothermal reaction, cooling, washing, drying and grinding to obtain the sodium manganate / MoS2 composite material. The composite material disclosed by the invention has good adsorption performance on cesium ions, is suitable for treating radioactive wastewater, still shows excellent selective adsorption capacity under different pH conditions and an environment in which multiple metal cations coexist, and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the field of radioactive wastewater treatment, and in particular to a sodium manganese silicate mesoporous silicate composite material for adsorbing cesium ions in radioactive wastewater, a preparation method and an application thereof. Background Art

[0002] The rapid development of nuclear power technology inevitably produces a large amount of wastewater containing radioactive nuclides, such as 137Cs and 90Sr, which has aroused people's concerns about environmental and social security. If these wastewaters containing radioactive nuclides are not properly treated or leak into the environment due to sudden natural disasters, they will bring huge potential hazards to the ecosystem and human society. In particular, cesium (137Cs), a radioactive nuclide with a relatively long half-life (30.1 years) and high gamma ray radiation (661.9 KeV), has more prominent potential hazards and may cause a series of biological diseases, causing immeasurable negative impacts on humans and the ecological environment. Therefore, in order to ensure the safety of the ecosystem and human health, it is of vital importance to remove cesium ions in aqueous solutions, especially in radioactive wastewater.

[0003] The current preferred options for treating this type of wastewater include the following: inducing precipitation reactions through chemical means, using solvents for extraction, applying membrane technology to achieve separation, and using various materials for adsorption. (1) Chemical precipitation is a method that adds flocculants to wastewater containing radioactive elements and uses redox reactions to generate insoluble compounds between the radioactive elements and the flocculants. In actual operation, it is widely adopted due to its simplicity, low cost, and adaptability to large-scale wastewater treatment. However, this method also has limitations, such as low separation efficiency and the possibility that the radioactive sludge after precipitation may cause secondary pollution problems. (2) Solvent extraction is a classic separation process, the core of which is to utilize the relative solubility difference of the target in two immiscible liquids. This method mainly relies on the adsorption of special extractants to separate cesium ions and shows excellent potential in treating cesium-containing wastewater. Although its application prospects are considered positive, the technology faces two major obstacles: first, the relatively high production cost, and second, the need for a relatively harsh reaction environment. These limiting factors not only increase the overall cost of the extraction process, but may also have adverse effects on the environment. (3) Membrane separation technology has been widely used in advanced fields of water treatment and wastewater management, mainly due to its simple operation steps and mild treatment conditions. Although membrane separation technology is highly efficient, stable and environmentally friendly in the treatment of radioactive wastewater without causing secondary pollution, the high cost of membrane materials and the limitation of its treatment efficiency have hindered its application in a wider range of fields. In addition, traditional filter membranes may suffer surface structural damage due to radiation exposure when exposed to highly radioactive substances for a long time, which not only reduces its interception effect on radioactive isotopes, but also may reduce the service life of the filter membrane. (4) The adsorption method effectively removes cesium ions from wastewater through the ion exchange, complexation and electrostatic interaction mechanism of the adsorbent, making it tightly attached to the surface of the adsorbent. This method can be widely used to remove cesium ions, thanks to its easily accessible raw materials, low cost, excellent removal effect, simple operation process and no secondary pollution. According to their composition, adsorbents are divided into two types: organic and inorganic. Although inorganic adsorbents have weaker cesium ion adsorption capacity than organic adsorbents, they are more resistant to radiation and more suitable for adsorbing nuclides in real radioactive environments. Therefore, the development of inorganic adsorbents with excellent performance is particularly critical for the removal of cesium ions. Summary of the invention

[0004] The purpose of the present invention is to solve the above-mentioned problems in the prior art and provide a sodium manganese silicate mesoporous silicate composite material for adsorbing cesium ions in radioactive wastewater, a preparation method and an application thereof. The sodium manganese silicate mesoporous silicate composite material has the advantages of being able to be stably reused under different pH environments, having good adsorption properties, high efficiency and the like, and has broad application prospects in the field of radioactive wastewater treatment.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] A method for preparing a sodium manganese silicate mesoporous silicate composite material for adsorbing cesium ions in radioactive wastewater comprises the following steps:

[0007] 1) Hydrothermally react NaMoO4·H2O and CSN2H4, centrifuge, wash and dry to obtain flower-ball-shaped MoS2, and irradiate the flower-ball-shaped MoS2 with electron beam for improvement;

[0008] 2) The modified flower-ball-shaped MoS2 and manganese silicate are mixed, then subjected to hydrothermal reaction, centrifuged, washed, dried and ground to obtain a composite material.

[0009] In step 1), NaMoO4·H2O and CSN2H4 are dissolved in deionized water at a mass ratio of 1:1-3 (preferably 1:2-3), and stirred at a speed of 150-250 rpm for 0.3-1 h; preferably, the speed is 200 rpm and the stirring time is 0.5-0.7 h.

[0010] In step 1), the hydrothermal reaction is as follows: the mixed solution is transferred to a stainless steel reaction vessel filled with polytetrafluoroethylene and maintained at 150-250° C. for 15-25 hours; preferably, the temperature is 200-220° C. and the time is 18-20 hours.

[0011] In step 1), the washing is: washing the obtained black precipitate with deionized water for 3 times; the drying is: drying the black precipitate at 50-80°C for 20-30h to obtain flower ball-shaped MoS2; preferably, the drying temperature is 60°C and the drying time is 22-25h.

[0012] In step 1), the flower ball-shaped MoS2 is irradiated with an electron beam, the irradiation energy is 1~10MeV, the beam current intensity is 50~300mA, and the irradiation time is 1~4h; preferably, the irradiation energy is 3~8MeV, the beam current intensity is 100~200mA, and the irradiation time is 2~3h.

[0013] In step 2), the method for mixing the modified flower-ball-shaped MoS2 and manganese silicate is as follows: first, the modified flower-ball-shaped MoS2 and Na2SiO3·9H2O are dissolved in water and ultrasonically treated to obtain a mixed solution; then (CH3COO)2Mn·4H2O is dissolved in water, and the mixture is added dropwise to the mixed solution at a rate of 1~3 mL / min and stirred thoroughly. Preferably, the dropping rate is 1~2 mL / min.

[0014] In step 2), the ultrasonic treatment is to dissolve the modified flower ball-shaped MoS2 and Na2SiO3·9H2O in deionized water and perform ultrasonic treatment for 20 to 40 minutes, preferably for 30 minutes.

[0015] In step 2), the stirring is that the mixture is stirred at 150-250 rpm for 1.5-3 h; preferably, the rotation speed is 180-200 rpm and the stirring time is 2 h.

[0016] In step 2), the mass ratio of MoS2, Na2SiO3·9H2O and (CH3COO)2Mn·4H2O is 1:4.7~123.5:0.75~20, preferably 1:12.3~59.1:2~9.6.

[0017] In step 2), the hydrothermal reaction is as follows: the mixture is transferred to a stainless steel reaction vessel lined with polytetrafluoroethylene, and reacted at 150-250°C for 10-14h, preferably at 180-200°C for 12h.

[0018] In step 2), the washing is to wash the precipitate with distilled water three times by centrifugation; the drying and grinding are to dry at 50-70°C for 20-25h and grind; preferably, the drying temperature is 60°C and the drying time is 24h.

[0019] Application of a sodium manganese silicate mesoporous silicate composite material for adsorbing cesium ions in radioactive wastewater, which can be applied to radioactive wastewater with various pH values ​​and containing alkali metal ions such as K + , Ca 2+ 、Na + It has the ability to selectively adsorb cesium ions in radioactive wastewater

[0020] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0021] The present invention compounds manganese silicate and flower-ball-shaped MoS2 to obtain a composite material that efficiently adsorbs cesium ions. The electron beam irradiation modification process of the present invention aims to increase the specific surface area and active sites through the interaction between high-energy electrons and the surface atoms of the flower-ball-shaped MoS2, and optimize the crystal structure to improve the adsorption capacity and mechanical stability of the material. The irradiation parameters such as the selection of irradiation energy of 1-10 MeV and beam intensity of 50-300 mA ensure effective modification without destroying MoS2, wherein the preferred irradiation conditions are 3-8 MeV energy and 100-200 mA intensity to achieve the best surface modification effect. In addition, (CH3COO)2Mn·4H2O is added dropwise at a rate of 1-3 mL / min to ensure that manganese ions are evenly distributed in the solution, fully react with the modified MoS2, and form a composite material with a stable structure, especially at the preferred dropwise acceleration rate of 1-2 mL / min, the uniformity of the reaction solution is optimal. The adjustment of the mass ratio of MoS2, Na2SiO3·9H2O and (CH3COO)2Mn·4H2O to 1:4.7~123.5:0.75~20 is based on the consideration of optimal adsorption efficiency and cost-effectiveness. Through these optimized designs, this technical solution significantly improves the removal efficiency of cesium ions in radioactive wastewater, has a wide pH adaptability range and high selective adsorption performance, and can efficiently remove cesium ions even in wastewater containing other alkali metal ions. At the same time, it has excellent radiation resistance and good regeneration performance, is economical and suitable for long-term stable operation, and provides a new solution with broad application prospects for the field of wastewater treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Figure a is a SEM (scanning electron microscope) image of the composite material mesoporous sodium manganese silicate / flower-shaped MoS2 prepared in Example 1; b and C are TEM (transmission electron microscope) images of mesoporous sodium manganese silicate / flower-shaped MoS2. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Unless otherwise specified, the reagents used in the following examples can be obtained from commercial sources.

[0024] Example 1

[0025] (1) 0.1 g NaMoO4·H2O and 0.15 g CSN2H4 were dissolved in deionized water respectively and stirred at 200 rpm for 0.5 h. The mixed solution was transferred to a stainless steel reaction vessel filled with polytetrafluoroethylene and kept at 200 °C for 20 h. The obtained black precipitate was washed with deionized water for 3 times and dried at 60 °C for 22 h to obtain flower ball-shaped MoS2. The flower ball-shaped MoS2 was irradiated with an electron beam with an irradiation energy of 5 MeV and a beam current of 150 mA for 2 h to obtain improved flower ball-shaped MoS2.

[0026] (2) 0.1 g of irradiated modified MoS2 and 2.84 g of Na2SiO3·9H2O were dissolved in 50 mL of deionized water and subjected to ultrasonic treatment for 30 min.

[0027] (3) Dissolve 0.46 g (CH3COO)2Mn·4H2O in 10 mL of deionized water and add it dropwise to the above solution at a rate of 1 mL / min.

[0028] (4) After the mixture was stirred at 200 rpm for 2 h, it was transferred to a 100 mL PTFE-lined stainless steel reaction vessel and reacted at 180 °C for 12 h.

[0029] (5) After cooling to room temperature, the precipitate was washed three times with distilled water by centrifugation, and then dried at 60 °C for 24 h and ground to obtain a composite material. The obtained composite material was scanned by SEM and TEM. Figure 1 shown.

[0030] (6) When the solution volume is 50 mL and Cs + Under the reaction conditions of initial concentration of 5.0 mg / L, pH = 8, adsorbent dosage of 1.0 g / L, and adsorption time of 1 h, the composite material prepared in step 5) was poured in.

[0031] (7) Pour out the liquid and take a sample for testing.

[0032] Example 2

[0033] The process is carried out in accordance with Example 1, except that the pH of the solution in step (6) is adjusted to 13.

[0034] Example 3

[0035] The process is carried out in accordance with Example 1, except that the pH of the solution in step (6) is adjusted to 2.

[0036] Example 4

[0037] The method is carried out in accordance with Example 1, except that the solution in step (6) is Na+ , K + , Ca 2+ , Cs + The initial concentrations of the mixed alkali metal solutions were 0.01 mol / L.

[0038] Comparative Example 1

[0039] The composite material was prepared according to Example 1, except that in step (1), the flower ball-shaped MoS2 was not modified by electron beam irradiation.

[0040] Comparative Example 2

[0041] The composite material is prepared in accordance with Example 1, except that in step (1), the spherical MoS2 is irradiated with an electron beam having an irradiation energy of 0.25 MeV and a beam intensity of 25 mA for 0.5 h to obtain an incompletely modified spherical MoS2.

[0042] Comparative Example 3

[0043] The composite material was prepared according to Example 1, except that in step (2), 0.01 g of irradiated modified flower ball-shaped MoS2 and 2.84 g of Na2SiO3·9H2O were dissolved in 50 mL of deionized water.

[0044] Comparative Example 4

[0045] The composite material was prepared according to Example 1, except that in step (2), 0.8 g of irradiated modified flower ball-shaped MoS2 and 2.84 g of Na2SiO3·9H2O were dissolved in 50 mL of deionized water.

[0046] Comparative Example 5

[0047] The composite material was prepared according to Example 1, except that in step (3), 0.46 g (CH3COO)2Mn·4H2O was dissolved in 10 mL of deionized water and added dropwise to the above solution at a rate of 5 mL / min.

[0048] Comparative Example 6

[0049] The same method was carried out as in Comparative Example 1, except that the pH of the solution was adjusted to 13.

[0050] Comparative Example 7

[0051] The same method was carried out as in Comparative Example 1, except that the pH of the solution was adjusted to 2.

[0052] Comparative Example 8

[0053] Refer to Comparative Example 1, except that the solution in step (6) is Na +, K + , Ca 2+ , Cs + The initial concentrations of the mixed alkali metal solutions were 0.01 mol / L.

[0054] Table 1

[0055]

[0056] The treated solutions were subjected to fitting analysis of the adsorption process by adsorption kinetics to detect the cesium ion removal rate, and the results are recorded in Table 1. As can be seen from Table 1, under the action of the composite material of the present invention, Cs ions in radioactive wastewater can be efficiently removed, and the effect is significantly better than that of the comparative example.

Claims

1. A method for preparing a sodium manganese silicate mesoporous silicate composite material for adsorbing cesium ions from radioactive wastewater, characterized in that: The following steps are involved: 1) Hydrothermally react NaMoO4·H2O and CSN2H4, centrifuge, wash and dry to obtain flower-ball-shaped MoS2, and irradiate the flower-ball-shaped MoS2 with electron beam for improvement; 2) The modified flower-ball-shaped MoS2 and manganese silicate are mixed, then subjected to hydrothermal reaction, centrifuged, washed, dried and ground to obtain a composite material.

2. The method for preparing a sodium manganese silicate mesoporous silicate composite material for adsorbing cesium ions from radioactive wastewater as claimed in claim 1, characterized in that: In step 1), the mass ratio of NaMoO4·H2O and CSN2H4 is 1:1~3.

3. The method for preparing a sodium manganese silicate mesoporous silicate composite material for adsorbing cesium ions from radioactive wastewater as claimed in claim 1, characterized in that: In step 1), the temperature of the hydrothermal reaction is maintained at 150-250° C. for 15-25 hours.

4. The method for preparing a sodium manganese silicate mesoporous silicate composite material for adsorbing cesium ions from radioactive wastewater as claimed in claim 1, characterized in that: In step 1), the flower ball-shaped MoS2 is irradiated with an electron beam, the irradiation energy is 1-10 MeV, the beam current intensity is 50-300 mA, and the irradiation time is 1-4 h.

5. The method for preparing a sodium manganese silicate mesoporous silicate composite material for adsorbing cesium ions from radioactive wastewater as claimed in claim 1, characterized in that: In step 2), the method for mixing the modified flower-ball-shaped MoS2 and manganese silicate is as follows: first, the modified flower-ball-shaped MoS2 and Na2SiO3·9H2O are dissolved in water and ultrasonically treated to obtain a mixed solution; then (CH3COO)2Mn·4H2O is dissolved in water and added dropwise to the aforementioned mixed solution at a rate of 1-3 mL / min and stirred thoroughly.

6. The method for preparing a sodium manganese silicate mesoporous silicate composite material for adsorbing cesium ions from radioactive wastewater as claimed in claim 5, characterized in that: In step 2), the mass ratio of MoS2, Na2SiO3·9H2O and (CH3COO)2Mn·4H2O is 1:4.7~123.5:0.75~20.

7. The method for preparing a sodium manganese silicate mesoporous silicate composite material for adsorbing cesium ions from radioactive wastewater as claimed in claim 1, characterized in that: In step 2), the temperature of the hydrothermal reaction is maintained at 150-250° C. for 10-14 hours.

8. A sodium manganese silicate mesoporous silicate composite material for adsorbing cesium ions from radioactive wastewater, characterized in that: Prepared by any preparation method of claims 1 to 7.

9. The use of a sodium manganese silicate mesoporous silicate composite material for adsorbing cesium ions from radioactive wastewater as claimed in claim 8, characterized in that: Used to adsorb cesium ions in wastewater.

10. The use according to claim 9, characterized in that: The wastewater contains alkali metal ions other than cesium ions.

Images