A method for adsorbing radioactive iodide ions in radioactive wastewater

Abstract

The present invention discloses a method for adsorbing radioactive iodide ions in radioactive wastewater, which includes the following process: adding silver copper oxide to the radioactive wastewater, and the iodide ions in the radioactive wastewater react with the silver copper oxide, so that the concentration of iodide ions in the radioactive wastewater is reduced. The adsorption of radioactive iodide ions in radioactive wastewater by the silver copper oxide of the present invention belongs to chemical adsorption, which has the characteristics of fast adsorption speed, high adsorption efficiency and adsorption capacity, the adsorbed product is not easy to desorb, is easy to solidify and dispose, is convenient for recycling, is convenient to use and is not easily affected by interfering ions and pH. The silver copper oxide has a strong selective adsorption effect on iodide ions in the wastewater environment of long half-life radioactive element iodine, and can effectively improve the radioactive pollution of iodine in the water environment, and solve the main problems of spent fuel reprocessing and radioactive water pollution.

Description

Technical Field

[0001] The present invention belongs to the technical field of nuclear waste treatment, and particularly relates to a method for adsorbing radioactive iodide ions in radioactive wastewater. Background Art

[0002] Radioactive iodine is an inevitable product of nuclear fission. If it is released into the environment, the radioactive iodine in water bodies can easily enter the human body through drinking water, fish and other channels, and thus be rapidly and selectively enriched by the thyroid gland, causing the human body to be continuously irradiated with a relatively large dose, leading to thyroid diseases and even cancer. Therefore, it is of great significance to treat radioactive iodine in spent fuel or contaminated nuclear wastewater.

[0003] The traditional treatment process is mainly the solid-phase adsorption method. However, when removing iodide ions in radioactive wastewater, problems such as poor selective adsorption of iodide ions, large desorption rate of the adsorbed product, difficulty in subsequent fixation treatment, low adsorption efficiency and slow adsorption speed will occur. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a method for adsorbing radioactive iodide ions in radioactive wastewater, and the present invention can efficiently adsorb iodide ions in radioactive nuclear wastewater.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A method for adsorbing radioactive iodide ions in radioactive wastewater, comprising the following process:

[0007] Adding silver copper oxide to radioactive wastewater, and the iodide ions in the radioactive wastewater react with the silver copper oxide to reduce the concentration of iodide ions in the radioactive wastewater.

[0008] Preferably, the pH value range of the radioactive wastewater is 3.5 - 11.5.

[0009] The adsorption method of the present invention further includes a process for adjusting the pH value of radioactive wastewater: when the pH value of the radioactive wastewater is less than 3.5, ammonia water is used to adjust the pH value to 3.5 - 11.5; when the pH value of the radioactive wastewater is greater than 11.5, nitric acid is used to adjust the pH value to 3.5 - 11.5.

[0010] Preferably, the volume-mass ratio of silver copper oxide to radioactive wastewater is 1 mg / ml.

[0011] Preferably, the concentration of iodide ions in the radioactive wastewater is 760 ppm - 1020 ppm.

[0012] Preferably, the reaction temperature of the radioactive wastewater and the silver copper oxide is 22 - 28 °C, and the reaction time is 50 - 70 min.

[0013] Preferably, after adding silver copper oxide to the radioactive wastewater, ultrasonic stirring is first carried out until the silver copper oxide is completely dispersed, and then oscillation and / or stirring are carried out during the reaction process of the radioactive wastewater and the silver copper oxide.

[0014] Preferably, the radioactive wastewater includes nitrate ions, carbonate ions, sulfate ions, bicarbonate ions, chloride ions and iodide ions.

[0015] Preferably, the adsorption capacity of silver copper oxide for iodide ions in radioactive wastewater is above 700 mg / g.

[0016] Preferably, the silver copper oxide is Ag2Cu2O3.

[0017] The present invention has the following beneficial effects:

[0018] In the method for adsorbing radioactive iodide ions in radioactive wastewater of the present invention, the adsorption of radioactive iodide ions in radioactive wastewater by silver copper oxide belongs to chemical adsorption, which has the characteristics of fast adsorption speed. After testing, the adsorption equilibrium can be reached in 50 min - 70 min, with high adsorption efficiency and adsorption capacity. The adsorption capacity for iodide ions is as high as above 700 mg / g. The adsorbed product is not easy to desorb, is easy to solidify and dispose, is convenient for recovery, is easy to use and is not easily affected by interfering ions and pH. The silver copper oxide has a strong selective adsorption effect on iodide ions in the wastewater environment of long half-life radioactive element iodine, can effectively improve the radioactive pollution of iodine in the water environment, and solve the main problems of spent fuel reprocessing and radioactive water pollution. Brief Description of the Drawings

[0019] Figure 1 It is the transmission electron microscope image of Ag2Cu2O3 of the silver copper oxide adopted by the present invention;

[0020] Figure 2 It is the transmission electron microscope image of Ag2Cu2O3 of the silver copper oxide of the present invention after fully adsorbing iodide ions;

[0021] Figure 3 It is the isothermal adsorption diagram of iodide ion concentration of 63.45 - 1649.7 ppm in Example 1 of the present invention;

[0022] Figure 4 It is the kinetic adsorption diagram in Example 2 of the present invention;

[0023] Figure 5 It is the experimental diagram of the influence of solution pH on iodide ion adsorption in Example 3 of the present invention;

[0024] Figure 6 It is the experimental diagram of the influence of interfering ions on iodide ion adsorption in Example 4 of the present invention;

[0025] Figure 7 This is the desorption diagram of the product after iodine ion attachment in Example 5 of the present invention; Detailed implementation manners

[0026] The present invention will be further described below in conjunction with the drawings and embodiments.

[0027] The purpose of the present invention is to solve the problems of poor selective adsorption of iodine ions in wastewater, high desorption rate of the product after adsorption, low adsorption efficiency and slow adsorption speed. The silver copper oxide provided by the present invention in the method for removing iodine ions from wastewater has an extremely low desorption rate, less than 1%, is easy to be fixed and disposed, has a high adsorption capacity, up to more than 700 mg / g, a fast adsorption speed, and can reach adsorption equilibrium within 50 - 70 minutes, which provides the possibility for highly selective treatment of radioactive iodine-containing wastewater.

[0028] Specifically, the method for adsorbing radioactive iodine ions in radioactive wastewater of the present invention comprises the following steps:

[0029] Step 1) Weigh 20 mg of silver copper oxide and add it into 20 mL of iodine ion solution respectively, stir ultrasonically until completely dispersed, and react under the condition of water bath oscillation at 22 - 28 °C. The concentration of iodine ions in the iodine ion solution is 762 ppm - 1016 ppm.

[0030] Step 2) For the iodine ion solution with the concentration described in Step 1), detect it at different times, and detect its dynamic adsorption degree of iodine ions within 1 minute - 24 hours.

[0031] Step 3) Add 20 mg of silver copper oxide powder into 20 mL of iodine ion solution with different pH values (pH = 3.5 - 11.5) respectively. The pH range of the solution is 3.5 - 11.5, and the pH value is adjusted with nitric acid and ammonia water. Stir ultrasonically until completely dispersed, and react under the condition of water bath oscillation at 22 - 28 °C. The concentration of iodine ions in the iodine ion solution is 762 ppm. Then measure the remaining iodine ion concentration of the filtrate of this series of solutions after reacting for 24 hours, and monitor the adsorption degree of silver copper oxide to iodine ions under different pH values.

[0032] Step 4) 20 mg of silver copper oxide was added to 20 ml of an iodide ion solution containing a large amount of other interfering ions, including nitrate, carbonate, sulfate, bicarbonate, and chloride, with a concentration ratio of 1000:1. The solution was ultrasonically stirred until completely dissolved, and then reacted in a 22-28°C water bath with shaking for 24 hours, resulting in an iodine ion concentration of 0.762 ppm and an interfering ion concentration of 762 ppm. The filtrates of these solutions were then tested for residual iodide ion to monitor the degree of adsorption of iodide ion in the presence of a large amount of other interfering ions.

[0033] Step 5) The product of step 2) after 24 hours of reaction is placed in water, ultrasonically stirred until completely dispersed, and then shaken in a water bath. The iodide ion concentration in the solution is measured at different times of 30-50 hours to monitor the dynamic desorption of the adsorbed iodide ions.

[0034] Example 1

[0035] The method for adsorbing radioactive iodine ions in radioactive wastewater in this embodiment comprises the following steps:

[0036] Step 1) Weigh 20 mg of Ag2Cu2O3 powder (the powder TEM image is as follows Figure 1 The powders were added to 20 mL of iodide ion solutions of different concentrations, the concentrations of which were 63.45 ppm, 126.9 ppm, 253.8 ppm, 380.7 ppm, 507.6 ppm, 634.5 ppm, 761.4 ppm, 888.3 ppm, 1015.2 ppm, 1142.1 ppm, 1269 ppm, 1395.9 ppm, 1522.8 ppm and 1649.7 ppm, respectively, and ultrasonically vibrated for 3 minutes to completely disperse the powder in the iodide ion solution, and then reacted in a water bath at 22-28° C. for 24 h;

[0037] Step 2) The solution after reaction for 24 hours in step 1) was taken out, and the supernatant was filtered using a disposable sterile syringe and a disposable water filter, and finally the iodine ion concentration after filtration was measured using a UV-visible spectrophotometer. e , through the formula Q e =(ρ0-ρ e )V / m can be used to calculate the adsorption capacity Q e , where Q e is the adsorption capacity at different concentrations, ρ0 is the initial concentration, ρ e is the concentration after adsorption, V is the volume of the solution, and m is the mass of the adsorbent; while the reaction product of step 1) with an iodide ion solution having a solubility greater than or equal to 761.4 ppm is centrifuged and dried, the transmission electron microscopy image of the powder is as follows Figure 2as shown

[0038] The results of the isothermal adsorption experiment in step 3) are as Figure 3 shown. Ag2Cu2O3 has a large adsorption capacity for iodide ions. As the initial concentration of iodide ions increases, the adsorption capacity also continuously increases, and the adsorption capacity at equilibrium can reach 745.5 mg / g.

[0039] Example 2

[0040] The method for adsorbing radioactive iodide ions in radioactive wastewater in this example includes the following steps:

[0041] Step 1) Weigh 20 mg of Ag2Cu2O3 powder (the transmission electron micrograph of this powder is as Figure 1 shown) and add it to 20 ml of an iodide ion solution with a concentration of 634.5 ppm. After ultrasonic stirring until completely dispersed, react under the condition of water bath oscillation at 22 - 28 °C.

[0042] Step 2) Conduct kinetic detection on the reaction in step 1), that is, when the reaction time t reaches 1, 5, 10, 30, 60, 120, 300, 480, 900, 1200, and 1440 minutes, conduct detection. That is, at the above times, take the supernatant and filter it with a disposable sterile syringe and a disposable water-based filter, and finally measure the concentration ρ e of iodide ions after filtration with a UV-visible spectrophotometer. Through the formula Q e =(ρ0 - ρ e )V / m, the adsorption capacity Q e can be calculated, where Q e is the adsorption capacity at time t, ρ0 is the initial concentration, ρ e is the concentration after adsorption, V is the solution volume, and m is the mass of the adsorbent.

[0043] 3) The kinetic adsorption results are as Figure 4 shown. The adsorption time of Ag2Cu2O3 for iodide ions is very fast, and the adsorption equilibrium is reached within 50 - 70 min, indicating that its adsorption efficiency is very high.

[0044] Example 3

[0045] The method for adsorbing radioactive iodide ions in radioactive wastewater in this example includes the following steps:

[0046] Step 1) Weigh 20 mg of Ag2Cu2O3 powder (the transmission electron micrograph of this powder is as Figure 1were separately added to 20 mL of iodide ion solutions with different pH values (pH = 3.5 - 11.5). The pH range of the solution was 3.5 - 11.5, and the pH value was adjusted with nitric acid and ammonia water. After ultrasonic stirring until completely dispersed, the reaction was carried out under the condition of water bath oscillation at 22 - 28 °C. The iodide ion concentration in the iodide ion solution was 634.5 ppm;

[0047] After step 2), the remaining iodide ion concentration in the filtrate of the solution in step 1) after 24 hours of reaction was measured. That is, the supernatant was taken and filtered with a disposable sterile syringe and a disposable water-based filter. Finally, the iodide ion concentration ρ of the filtered solution was measured with a UV-visible spectrophotometer e , through the formula Q e =(ρ0 - ρ e )V / m, the adsorption capacity Q e can be calculated. Among them, Q e is the adsorption capacity at different pH values, ρ0 is the initial concentration, ρ e is the concentration after adsorption at different pH values, V is the solution volume, and m is the mass of the adsorbent; thus, the adsorption degree of Ag2Cu2O3 for iodide ions under different pH values can be known;

[0048] The results of the influence of pH on the adsorption of iodide ions by Ag2Cu2O3 are as Figure 5 shown. It can be seen that when the pH range is 3.5 - 11.5, the adsorption efficiency of iodide ions is still higher than 90%. Generally, radioactive wastewater is usually acidic, so it can be known that this will not affect the use of Ag2Cu2O3 to treat radioactive wastewater.

[0049] Example 4

[0050] The method for adsorbing radioactive iodide ions in radioactive wastewater in this example includes the following steps:

[0051] Step 1) Weigh 20 mg of Ag2Cu2O3 powder (the transmission electron micrograph of this powder is as Figure 1 shown) and separately add it to 20 ml of iodide ion solution containing a large number of other interfering ions. Among them, the other interfering ions include nitrate ions, carbonate ions, sulfate ions, bicarbonate ions, and chloride ions. The concentration of interfering ions is 640 ppm, and the iodide ion concentration is 0.64 ppm. After ultrasonic stirring until completely dissolved, the reaction is carried out under the condition of water bath oscillation at 22 - 28 °C for 24 h;

[0052] After step 2), the remaining iodide ions in the filtrate of the solution in step 1) are detected. Filter it with a disposable sterile syringe and a disposable water-based filter. Finally, measure the iodide ion concentration ρ of the filtered solution with a UV-visible spectrophotometer e , through the formula Q e =(ρ0 - ρe )V / m can be used to calculate the adsorption capacity Q e , where Q e is the adsorption capacity under the action of different interfering ions, ρ0 is the initial concentration, ρ e is the concentration after adsorption under the action of different interfering ions, V is the volume of the solution, and m is the mass of the adsorbent; thus, the adsorption degree of Ag2Cu2O3 for iodide ions under different interfering ion conditions can be known;

[0053] Step 3) The results of the influence of interfering ions on the adsorption of iodide ions are as Figure 6 shown. When Ag2Cu2O3 adsorbs iodide ions in the presence of a large amount of other interfering ions, the adsorption efficiency still exceeds 95%, indicating its high selective adsorption, which shows that this material is suitable for the case where the solution contains a large amount of nitrate ions, carbonate ions, sulfate ions, bicarbonate ions, and chloride ions.

[0054] Example 5

[0055] The method for adsorbing radioactive iodide ions in radioactive wastewater in this example includes the following steps:

[0056] Step 1) Weigh 20 mg of Ag2Cu2O3 powder (the transmission electron microscope image of this powder is as Figure 1 shown), add it to 20 ml of an iodide ion solution with a concentration of 634.5 ppm, ultrasonically stir until completely dispersed, react for 24 h under the condition of water bath oscillation at 22 - 28 °C, detect the iodide ions in the filtrate of the reaction solution, filter it with a disposable sterile syringe and a disposable water-based filter, and finally measure the concentration ρ of the filtered iodide ions with a UV-visible spectrophotometer e , and the adsorption capacity Q can be calculated through the formula Q e =(ρ0 - ρ e )V / m e , where Q e is the adsorption capacity under the action of different interfering ions, ρ0 is the initial concentration, ρ e is the concentration after adsorption under the action of different interfering ions, V is the volume of the solution, and m is the mass of the adsorbent;

[0057] Step 2) Put the reaction product in Step 1 into water, wash it 3 times with deionized water and anhydrous ethanol respectively, centrifuge it, and dry it in an oven at 60 ± 2 °C to obtain the dried powder

[0058] Step 3) Weigh 20 mg of the powder dried in Step 2 and add it to 20 ml of deionized water. After ultrasonic stirring until completely dispersed, shake it in a water bath at 22 - 28 °C. Measure the iodide ion concentration in the solution after different times of 5, 10, 20, 30, 40, and 50 h. Detect the iodide ions in the filtrate of the solution after different reaction times, filter it with a disposable sterile syringe and a disposable water-based filter, and finally measure the iodide ion concentration ρ of the filtered solution with a UV-visible spectrophotometer. t , through the formula Q t = ρ t V / m, the desorption capacity Q can be calculated. t , where Q t is the desorption capacity under different times of action, ρ t is the concentration after desorption under different times of action, V is the solution volume, and m is the mass of the desorbent; thus, the desorption situation after Ag2Cu2O3 adsorbs iodide ions can be known.

[0059] The desorption results are as Figure 7 shown. The results show that the desorption rate of the product after Ag2Cu2O3 adsorption is less than 1%. It can be seen that Ag2Cu2O3 has a very high solidification effect on iodide ion adsorption, good stability, is not easy to desorb, and is convenient for subsequent solidification treatment.

Claims

1. A method for adsorbing radioactive iodide ions in radioactive wastewater, characterized in that, It includes the following processes: Adding silver copper oxide to the radioactive wastewater, and the iodide ions in the radioactive wastewater react with the silver copper oxide to reduce the concentration of iodide ions in the radioactive wastewater; The silver copper oxide is Ag2Cu2O3; The concentration of iodide ions in the radioactive wastewater is 760 ppm - 1020 ppm.

2. The method for adsorbing radioactive iodide ions in radioactive wastewater according to claim 1, wherein The pH value range of the radioactive wastewater is 3.5 - 11.

5.

3. The adsorption method of radioactive iodide ions in radioactive wastewater according to claim 2, characterized in that, It also includes the process of adjusting the pH value of the radioactive wastewater: when the pH value of the radioactive wastewater is less than 3.5, ammonia water is used to adjust the pH value to 3.5 - 11.5; when the pH value of the radioactive wastewater is greater than 11.5, nitric acid is used to adjust the pH value to 3.5 - 11.

5.

4. A method for adsorbing radioactive iodide ions in radioactive wastewater according to claim 1, characterized in that, The volume - mass ratio of silver copper oxide to radioactive wastewater is 1 mg / ml.

5. The adsorption method of radioactive iodide ions in radioactive wastewater according to claim 1, characterized in that, The reaction temperature of the radioactive wastewater and silver copper oxide is 22 - 28 °C, and the reaction time is 50 - 70 min.

6. The method for adsorbing radioactive iodide ions in radioactive wastewater according to claim 1, characterized in that, After adding silver copper oxide to the radioactive wastewater, ultrasonic stirring is first carried out until the silver copper oxide is completely dispersed, and then oscillation and / or stirring are carried out during the reaction process of the radioactive wastewater and silver copper oxide.

7. A method for adsorbing radioactive iodide ions in radioactive wastewater according to claim 1, characterized in that, The radioactive wastewater contains nitrate ions, carbonate ions, sulfate ions, bicarbonate ions, chloride ions and iodide ions.

8. The adsorption method of radioactive iodide ions in radioactive wastewater according to claim 1, characterized in that, The adsorption capacity of silver copper oxide for iodide ions in the radioactive wastewater is above 700 mg / g.

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