CN110801818A - A composite functional material for removing radioactive iodine and its application - Google Patents

Abstract

The invention provides a composite functional material for removing radioactive iodine and its application. The technical scheme combines the mussel biomimetic chemical method to polymerize dopamine monomer on the surface of the titanium silicon carbide powder material etched by hydrofluoric acid as a secondary The secondary reaction platform is then loaded with nano-sized Bi ₆ O ₇ particles to obtain a powdered two-dimensional layered composite functional adsorbent for removing radioactive iodide ions in the waste liquid. In the present invention, the material synthesis method is simple, the sensitivity of the reaction conditions is low, the synthesized adsorbent material is a two-dimensional layered structure, has a large specific surface area, increases the reactive sites, and has good comprehensive performance and high stability. , the adsorption rate is significantly improved, and it is an effective adsorbent for the treatment of iodide ions in radioactive waste liquid. The nanometer Bi ₆ O ₇ particles and iodide ions on the surface of the material form bismuth iodide crystallites. As an adsorbent, the adsorption rate is high, the adsorption stability time is about 50 minutes, and the iodide ion removal rate can reach about 70%.

Description

A composite functional material for removing radioactive iodine and its application

technical field

The invention relates to the technical field of environmental materials, further relates to the purification treatment technology of radioactive waste liquid in environmental protection, and in particular relates to a composite functional material for removing radioactive iodine and its application

Background technique

Radioactive iodine refers to radioactive isotopes of iodine, mainly including ¹²⁹ I, ¹³¹ I, ¹²³ I, ¹²⁴ I and ¹²⁵ I and the like. As one of the products of nuclear fission, radioactive iodine widely exists in nuclear fission waste liquid in the form of ¹³¹ I, and its half-life ranges from 8.04 days to 1.57×10 ⁷ years. It can flow in natural water bodies. In addition, radioactive iodine is also widely used in the medical field, such as ¹³¹ I for the treatment of hyperthyroidism and thyroid cancer, ¹²⁵ I for thyroid tumor biopsy, thyroid scan and radioimmunoassay measurement, etc. Radioactive iodine is extremely harmful to the human body, and its accumulation in the human body may lead to diseases such as metabolic disorders, leukemia, and thyroid cancer. Therefore, the harmless treatment of radioactive iodine is an important technical means to reduce pollution and ensure public safety.

In the prior art ^, the methods for removing I mainly include ion exchange method, membrane separation method, precipitation method, adsorption method, etc., wherein the adsorption method is the main removal method in practical application, and it has the advantages of simplicity and convenience, easy operation, and removal There are many advantages of high rate. However, the pros and cons of its effect greatly depend on the properties of the adsorbent material itself. Therefore, the development of an efficient adsorbent material is the key to ensure the effective implementation of such methods. In the prior art, conventional adsorption materials for removing radioactive iodide ions are inefficient and inconvenient to prepare and use.

SUMMARY OF THE INVENTION

The present invention aims to provide a composite functional material for removing radioactive iodine and its application in view of the technical defects of the prior art, so as to solve the technical problem of low adsorption efficiency of conventional iodine ion adsorption materials in the prior art.

Another technical problem to be solved by the present invention is that the conventional iodide ion adsorption material is inconvenient to prepare, and the controllability of the preparation process is low.

To achieve the above technical purpose, the present invention adopts the following technical solutions:

A composite functional material for removing radioactive iodine, the composite functional material is prepared by the following method:

1) mixing titanium silicon carbide with excess hydrofluoric acid and reacting, centrifuging the solid phase after the reaction, washing, and drying to obtain MXene material;

2) Dissolving the MXene material obtained in step 1) in a solution with a pH of 8 to 9, ultrasonically vibrating, adding dopamine and stirring, washing and centrifuging after the reaction, taking the solid phase, and drying to obtain the MXene-PDA material ;

3) using ethanol and ethylene glycol as a solvent and using bismuth nitrate pentahydrate as a solute to prepare a solution, adding the MXene-PDA material obtained in step 2) into it, ultrasonically dispersing, reacting, washing and centrifuging after the reaction, and taking the solid phase, After drying, the composite functional material is obtained.

Preferably, in step 1), the hydrofluoric acid is a hydrofluoric acid solution with a concentration greater than 40%; the dosage ratio of titanium silicon carbide and the hydrofluoric acid solution with a concentration greater than 40% is 3g:80mL.

Preferably, the solution described in step 2) is a tris(hydroxymethyl)aminomethane solution.

Preferably, the solution described in step 3), wherein the volume ratio of ethanol and ethylene glycol is 2:1.

Preferably, the mass ratio of MXene material to dopamine in step 2) is 5:3.

Preferably, the rotating speed of the centrifugation is not less than 5000r/min; the drying treatment is freeze-drying; the washing described in step 2) is realized by using ethanol and ultrapure water; step 1) and steps 3) The washing is realized by using ultrapure water.

Preferably, step 1) includes: adding 3 g of titanium silicon carbide powder to the tetrafluoroethylene-lined reaction kettle, then adding a hydrofluoric acid solution with a concentration greater than 40% dropwise to it until the excess, and vigorously stirring during the dropwise addition, After the reaction is stable, ultrasonically vibrate for 5 min, and then react at 60 °C for 48 h. After the reaction is completed, cool to room temperature, centrifuge at 6000 r/min to take the solid phase, and wash with ultrapure water for 3 to 5 times to remove the hydrogen that does not participate in the reaction. hydrofluoric acid, freeze-dried for 24 h to obtain MXene material.

Preferably, step 2) includes: dissolving 61 mg of tris(hydroxymethyl)aminomethane in 50 mL of ultrapure water to prepare a solution with a pH of 8 to 9, dissolving 1 g of the MXene material obtained in step 1) in the solution, and ultrasonically oscillating for 5 to 10 min Until the material is uniformly dispersed, add 500 mg of dopamine to it and shake it ultrasonically for 5 min, stir at room temperature for 6 h, wash with ultrapure water and ethanol after the reaction until the solution changes from yellow to colorless, and centrifuge the solid phase at 5000 r/min. , freeze-dried for 12 h to obtain MXene-PDA material.

Preferably, step 3) includes: fully mixing 34 mL of ethanol and 17 mL of ethylene glycol, then dissolving 0.97 g of bismuth nitrate pentahydrate therein, ultrasonically and fully stirring until the bismuth nitrate is completely dissolved, and then MXene- The PDA material was added into it, ultrasonically dispersed for 30min, and then the obtained suspension was moved to a tetrafluoroethylene-lined reaction kettle, and the reaction was sealed at 160°C for 10h. After the reaction, washed with ultrapure water for 3 to 5 times until the solution was transparent. , the solid phase was obtained by centrifugation at a rotational speed of 5500 r/min, and freeze-dried for 24 h to obtain the composite functional material.

On the basis of the above technical solutions, the present invention further provides the application of the above composite functional material for adsorbing iodine ions.

Preferably, the application is to mix the composite functional material with a solution containing iodide ions, and the pH value of the solution containing iodide ions is 5-8.

In the above technical solutions, the MXene material is a two-dimensional inorganic compound, and these materials are composed of transition metal carbides, nitrides or carbonitrides with a thickness of several atomic layers. It is possible to be used as an adsorption material or adsorption substrate material. At the same time, as a two-dimensional layered material, it has a high specific surface area. If used as a substrate material, it can greatly increase the adsorption active sites and rapidly increase the reaction rate. The mussel biomimetic technology mainly uses the self-polymerization of dopamine in solution to form a stable polydopamine polymer coating. This reaction is less sensitive to conditions and does not require stimulation from the external environment, and the formed coating can almost adhere On the surface of any solid material, and no surface pretreatment is required for the base material, the technology is easy to operate, has good controllability, and has high performance of synthetic materials.

The invention provides a composite functional material for removing radioactive iodine and its application. The technical scheme combines the mussel biomimetic chemical method, so that dopamine monomer can be etched by hydrofluoric acid on the surface of titanium silicon carbide powder (MXene) material. The polymerization is used as a secondary reaction platform to support nano-Bi ₆ O ₇ particles, and a powdered two-dimensional layered composite functional adsorbent is obtained to remove radioactive iodide ions in the waste liquid. In the present invention, the material synthesis method is simple, the sensitivity of the reaction conditions is low, the synthesized adsorbent material is a two-dimensional layered structure, has a large specific surface area, increases the reactive sites, and has good comprehensive performance and high stability. , the adsorption rate is significantly improved, and it is an effective adsorbent for the treatment of iodide ions in radioactive waste liquid. The composite functional material provided by the invention has a two-dimensional layered structure. The surface nano-Bi ₆ O ₇ particles and iodide ions form bismuth iodide microcrystals. As an adsorbent, the adsorption rate is high, and the adsorption stability time is about 50 minutes. The ion removal rate can reach about 70%.

The formation mechanism of bismuth-based oxide in step 3) of the present invention is that bismuth nitrate pentahydrate forms a complex with ethylene glycol first, and then decomposes to form a bismuth-based oxide when heated to a certain temperature. The reaction complex equation is: Bi(NO ₃ ) ₃ 5H ₂ O+HOCH ₂ CH ₂ OH+C ₂ H ₅ OH→Bi ₂ (OCH ₂ CH ₂ O) ₃ +C ₂ H ₅ ONO ₂ +H ₂ O, the decomposition equation of the formed bismuth-based complex is : Bi ₂ (OCH ₂ CH ₂ O) ₃ +H ₂ O→Bi ₆ O ₇ +HOCH ₂ CH ₂ OH+O ₂ .

The present invention is used as a composite functional material for the adsorption of iodide ions in radioactive waste liquid.

The mechanism equation for the adsorption of iodide ions by bismuth-based oxides is: Bi ₆ O ₇ +I ^- +O ₂ +H ₂ O→Bi ₄ I ₂ O ₅ +OH ^- .

Compared with the prior art, the advantages of the present invention are: the present invention proposes a two-dimensional layered MXene material as the substrate, which has a larger specific surface area, which increases the reactive sites, and combines the mussel biomimetic chemical method to carry the material. Compared with the traditional iodine ion removal method, the nanometer bismuth oxide is used to synthesize a high-efficiency iodine-removing adsorbent. Compared with the traditional iodine ion removal method, the invention has the advantages of simple operation, convenient synthesis, low secondary pollution to the environment, high iodide ion removal rate, significantly accelerated adsorption rate, and selectivity. Good and many other advantages.

Description of drawings

Fig. 1 is the scanning electron microscope picture of the material of the present invention;

Fig. 2 is the XRD pattern of the material of the present invention;

Fig. 3 is the adsorption kinetic curve diagram of the material of the present invention;

Fig. 4 is the isothermal adsorption line of the material of the present invention;

Figure 5 is a graph showing the effect of pH on the material of the present invention.

Detailed ways

Specific embodiments of the present invention will be described in detail below. In order to avoid unnecessary details, well-known structures or functions will not be described in detail in the following embodiments. The language of approximation used in the following examples can be used for quantitative expressions, showing that some variation in quantity is permissible without changing the basic function. Unless defined otherwise, technical and scientific terms used in the following examples have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

A composite functional material for removing radioactive iodine, the composite functional material is prepared by the following method:

(1) Take 3g of the purchased titanium silicon carbide powder raw material in a 100ml polytetrafluoroethylene lined reactor, then dropwise add HF (>40%) to the reactor until the excess (about 80ml) is added dropwise. With vigorous stirring during the process, after the reaction was stable, the obtained suspension was sonicated for 5 min, and then reacted at 60 °C for 48 h. After the reaction was completed, it was cooled to room temperature and centrifuged at 6000 r/min, and washed 3-5 times with ultrapure water. The HF that did not participate in the reaction was removed, and the obtained black powder was freeze-dried at low temperature for 24 h.

(2) First, weigh 61 mg of tris(hydroxymethylaminomethane) and dissolve it in 50 ml of ultrapure water to prepare an alkaline solution with a pH of 8-9, then add 1 g of the previously prepared MXene and ultrasonically oscillate for 5-10 min until the material is uniformly dispersed, then Add 500 mg of dopamine and sonicate for 5 min, stir at room temperature for 6 h, wash with ultrapure water and ethanol after the reaction until the solution changes from yellow to colorless, centrifuge at 5000 r/min, and freeze-dried the obtained solid at low temperature for 12 h.

(3) Measure 34ml of ethanol and 17ml of ethylene glycol and mix thoroughly, then weigh 0.97g (0.002mol) of bismuth nitrate pentahydrate and dissolve it in the above solution, ultrasonically and fully stir until the bismuth nitrate is completely dissolved, then the modified MXene The material was added to the alcoholic solution of bismuth nitrate pentahydrate by ultrasonic for 30min to make it fully dispersed, and the suspension was moved to a polytetrafluoroethylene-lined reactor and reacted for 10h under the sealing condition of 160℃. Washed with pure water for 3-5 times until the solution was transparent, centrifuged at 5500r/min, and finally freeze-dried at low temperature for 24h to obtain a gray-brown solid powder.

Observing the surface morphology of the final product under a scanning electron microscope is shown in Figure 1. It is found that the surface of the modified MXene has a petal-like structure, which is speculated to be a sheet-like nano-Bi ₆ O ₇ in the present invention.

Then, the specific phase of the MXene surface was determined by X-ray diffraction, and the fitted XRD curve was shown in Figure 2. According to the standard comparison card, it was determined that the surface material was flaky nano-Bi ₆ O ₇ .

The maximum adsorption capacity and adsorption kinetics of the adsorbent were studied, and the curve was drawn in Figure 3. It was found that the adsorbent reached equilibrium in about 50 minutes, and the maximum adsorption capacity was about 70 mg/g.

The adsorption isotherm is measured for the adsorbent, and the drawing curve is shown in Figure 4. According to the Langmuir adsorption isotherm model and the Freundlich adsorption isotherm model, the equilibrium data is fitted and it is found that the adsorbent of the present invention is based on monomolecular layer adsorption, and there is no adsorption in the adsorption process. The interference of other molecular layers, and the adsorption active sites are evenly distributed on the surface of the adsorbent, which also reflects from the side why the adsorption equilibrium time of the adsorbent is greatly improved, and also explains why the adsorbent does not rely on the diffusion model for particle diffusion. Complete the adsorption of iodide ions.

The present invention studies the effect of pH on the adsorption performance of the adsorbent, and the specific result is drawn as shown in Figure 5. According to the curve, it can be seen that when the pH is 5, the adsorbent reaches the maximum adsorption capacity of 44.05 mg/g, and with the increase of pH, The adsorption performance decreased gradually, while the maximum adsorption dropped sharply to 7.55 mg/g in the process of pH from 9 to 10, because the hydroxide concentration in the solution increased exponentially with the increase of pH, and the reaction solubility product did not change In some cases, the presence of a large amount of hydroxide hinders the chemical reaction of Bi ₆ O ₇ with iodide ions, resulting in a decrease in the adsorption performance.

The embodiments of the present invention have been described in detail above, but the above contents are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the scope of the application of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A composite functional material for removing radioactive iodine, characterized in that the composite functional material is prepared by the following method:

1) mixing silicon titanium carbide with excessive hydrofluoric acid, reacting, centrifuging after the reaction is finished, taking a solid phase, washing, and drying to obtain an MXene material;

2) dissolving the MXene material obtained in the step 1) in a solution with the pH value of 8-9, carrying out ultrasonic oscillation, adding dopamine into the solution, stirring, washing and centrifuging after the reaction is finished, taking a solid phase, and drying to obtain an MXene-PDA material;

3) preparing a solution by using ethanol and ethylene glycol as solvents and bismuth nitrate pentahydrate as a solute, adding the MXene-PDA material obtained in the step 2), performing ultrasonic dispersion and reaction, washing and centrifuging after the reaction is finished, taking a solid phase, and drying to obtain the composite functional material.

2. The composite functional material for removing radioactive iodine according to claim 1, wherein said hydrofluoric acid in step 1) is a hydrofluoric acid solution having a concentration of more than 40%; the dosage ratio of the silicon titanium carbide to the hydrofluoric acid solution with the concentration of more than 40 percent is 3g:80 mL.

3. The composite functional material for removing radioactive iodine according to claim 1, wherein the solution in step 2) is a tris solution.

4. The composite functional material for removing radioactive iodine according to claim 1, wherein the volume ratio of ethanol to ethylene glycol in the solution in step 3) is 2: 1.

5. The composite functional material for removing radioactive iodine according to claim 1, wherein the rotation speed of the centrifugation is not lower than 5000 r/min; the drying treatment is freeze drying; the washing in the step 2) is realized by using ethanol and ultrapure water; the washing in the step 1) and the step 3) is realized by using ultrapure water.

6. The composite functional material for removing radioactive iodine according to claim 1, wherein the step 1) comprises: adding 3g of silicon titanium carbide powder into a tetrafluoroethylene lined reaction kettle, dropwise adding a hydrofluoric acid solution with the concentration of more than 40% until the solution is excessive, violently stirring in the dropwise adding process, carrying out ultrasonic oscillation for 5min after the reaction is stable, reacting for 48h at 60 ℃, cooling to room temperature after the reaction is finished, centrifuging at the rotating speed of 6000r/min to take a solid phase, washing with ultrapure water for 3-5 times to remove the hydrofluoric acid which does not participate in the reaction, and freeze-drying for 24h to obtain the MXene material.

7. The composite functional material for removing radioactive iodine according to claim 1, wherein the step 2) comprises: dissolving 61mg of trihydroxymethyl aminomethane in 50mL of ultrapure water to prepare a solution with the pH value of 8-9, dissolving 1g of MXene material obtained in the step 1) in the solution, carrying out ultrasonic oscillation for 5-10min until the material is uniformly dispersed, adding 500mg of dopamine into the solution, carrying out ultrasonic oscillation for 5min, stirring the solution at room temperature for 6h, washing the solution by using ultrapure water and ethanol after the reaction is finished until the solution is colorless from yellow, centrifuging the solution at the rotating speed of 5000r/min to obtain a solid phase, and carrying out freeze drying for 12h to obtain the MXene-PDA material.

8. The composite functional material for removing radioactive iodine according to claim 1, wherein the step 3) comprises: fully mixing 34mL of ethanol and 17mL of ethylene glycol, dissolving 0.97g of bismuth nitrate pentahydrate in the mixed solution, performing ultrasonic treatment and fully stirring until the bismuth nitrate is completely dissolved, adding the MXene-PDA material obtained in the step 2), performing ultrasonic dispersion for 30min, transferring the obtained suspension into a tetrafluoroethylene lining reaction kettle, performing sealed reaction at 160 ℃ for 10h, washing with ultrapure water for 3-5 times after the reaction is finished until the solution is transparent, centrifuging at a rotating speed of 5500r/min to obtain a solid phase, and performing freeze drying for 24h to obtain the composite functional material.

9. Use of the composite functional material of any one of claims 1 to 8 for adsorbing iodide ions.

10. The use according to claim 9, wherein the composite functional material is mixed with a solution containing iodide ions, and the pH value of the solution containing iodide ions is 5-8.

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