Adsorption resin for treating cesium-containing waste liquid and preparation method thereof

Abstract

The invention relates to the technical field of cesium adsorption resin materials, and discloses an adsorption resin for treating cesium-containing waste liquid and a preparation method thereof, and the preparation method specifically comprises the following steps: 1, generating a polymer: dissolving resorcinol, formaldehyde and sodium bicarbonate in deionized water, heating, reducing pressure, slowly evaporating water, and forming the polymer after a period of time; 2, cooling the solid product overnight, washing with hydrochloric acid, soaking with water, and drying; and 3, crushing the polymer, repeatedly washing, and drying to finally obtain the adsorption resin. In the step 1, the mass of the resorcinol is 320-350 g, the formaldehyde is a 37% aqueous solution, the volume of the formaldehyde is 250-280 mL, the mass of the sodium bicarbonate is 200-205 g, and the volume of the deionized water is 4-5 L. The cesium adsorption resin prepared by the invention has the advantages of high selectivity, good adsorption effect, high mechanical strength and simple preparation method, and can be suitable for treating radioactive waste liquid with complex components and harsh conditions, such as nuclear waste storage tank supernatant.

Description

Technical Field

[0001] This invention relates to the field of cesium adsorption resin materials technology, specifically to an adsorption resin for treating cesium-containing waste liquid and its preparation method. Background Technology

[0002] The global use of nuclear energy and nuclear fuel reprocessing generates large quantities of waste containing high-level radioactive liquids, which are typically stored in large underground tanks. Among these wastes is radioactive cesium (especially ¹³). 7 Cesium (Cs) poses significant challenges to the long-term safety and stability of waste storage tanks, subsequent treatment processes, and the environment due to its high pyrolytic activity, long half-life of approximately 30 years, and easy migration in the environment. Therefore, efficient separation of cesium from the supernatant of waste from storage tanks is crucial for reducing the overall heat load of the tanks, lowering the radiation dose rate of subsequent solidification treatments, and even for potential recycling¹³ 7 Cs isotopes are of vital strategic importance. However, separating cesium from tank supernatants faces extremely harsh chemical and physical challenges. These waste liquids typically exhibit high ionic strength (high salt content), strong corrosivity, and even strong oxidizing properties. Simultaneously, the high dose of radiation present in the system can trigger radiodecomposition of water, generating reactive species such as hydroxyl radicals, which severely impact the structure and performance of the separation materials. Furthermore, any practical separation technology and its media must be able to withstand the mechanical forces in the process flow (such as bed expansion / contraction and particle abrasion), avoid bed fouling, and maintain long-term stable hydrodynamic performance and high throughput.

[0003] Currently, two ion exchange treatment methods are used to treat tank supernatant to remove cesium:

[0004] (1) Elutionable and regenerable organic ion exchange resins: After the adsorption of these materials (usually organic polymer resins) is saturated, the adsorbed cesium can be eluted by specific chemical reagents (such as acid or salt solutions), so that the resin can be regenerated and recycled, which helps to reduce the volume of secondary waste.

[0005] (2) Non-elutable inorganic ion exchangers: These materials (such as zeolites, heteropolyacids, ferrocyanides, etc.) are usually highly selective for cesium ions and generally have excellent radiation resistance. After adsorption, these materials are often solidified together with the adsorbed radionuclides (such as vitrification) rather than being regenerated for reuse.

[0006] Despite these studies, developing a novel ion exchange medium that can simultaneously meet the requirements of high selectivity, excellent chemical / radiative stability, good kinetic performance, and good mechanical strength remains a goal that those skilled in the art continue to strive for when processing the supernatant of nuclear waste storage tanks with complex composition and harsh conditions.

[0007] To address this issue, we propose an adsorption resin for treating cesium-containing wastewater and its preparation method. Summary of the Invention

[0008] The purpose of this invention is to provide an adsorption resin for treating cesium-containing waste liquid and a method for preparing the same, thereby solving the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: an adsorption resin for treating cesium-containing waste liquid, wherein the resin has the structure of Formula 1:

[0010]

[0011] Formula 1

[0012] This invention also includes an adsorption resin for treating cesium-containing wastewater and a method for preparing the resin, wherein the resin preparation steps are as shown in Formula 2:

[0013]

[0014] Formula 2

[0015] Specifically, the following steps are included:

[0016] Step 1: To generate a polymer, resorcinol, formaldehyde, and sodium bicarbonate are dissolved in deionized water, heated, and the pressure is reduced to allow the water to evaporate slowly. After a period of time, a polymer is formed.

[0017] Step 2: After cooling the solid product overnight, wash it with hydrochloric acid, then soak it in water, and then dry it.

[0018] Step 3: Crush the polymer, wash it repeatedly, and then dry it to obtain the adsorption resin.

[0019] Preferably, in step 1, the mass of resorcinol is 320-350 g, the formaldehyde is a 37% aqueous solution with a volume of 250-280 mL, the mass of sodium bicarbonate is 200-205 g, and the volume of deionized water is 4-5 L.

[0020] Preferably, in step 1, the heating temperature is 80-100℃.

[0021] Preferably, in step 2, the hydrochloric acid concentration is 0.5 mol / L and the water immersion time is 2-3 hours.

[0022] Preferably, in step 3, the polymer pulverization particle size is 500-1000µm, and the drying temperature is 80-100℃.

[0023] This invention provides an adsorption resin for treating cesium-containing wastewater and a method for preparing the same. The adsorption resin and its preparation method for treating cesium-containing wastewater have the following beneficial effects:

[0024] The cesium adsorption resin prepared by this invention has high selectivity, good adsorption effect, high mechanical strength, and simple preparation method. It can be applied to the treatment of radioactive waste liquids with complex composition and harsh conditions, such as the supernatant of nuclear waste storage tanks. Attached Figure Description

[0025] Figure 1 The image shows the FT-IR spectrum of resorcinol formaldehyde resin.

[0026] Figure 2 This is a SEM image of resorcinol-formaldehyde resin.

[0027] Figure 3 The adsorption kinetics curve of cesium on resorcinol-formaldehyde resin is shown. Detailed Implementation

[0028] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0029] Example 1

[0030] This embodiment provides a method for preparing an adsorption resin for treating cesium-containing waste liquid, comprising the following steps:

[0031] 330 g of resorcinol, 255 mL of 37% formaldehyde solution (molar ratio of resorcinol to formaldehyde 1.8:2.1), and 202 g of sodium bicarbonate were dissolved in 4 L of deionized water and transferred to a 10 L round-bottom flask. The flask was heated on a rotary evaporator at 100 °C under reduced pressure to allow the water to evaporate slowly. After heating for 2 hours, the resulting polymer was cooled overnight. The solid product was washed with 0.5 M hydrochloric acid, then soaked in water for 2 hours, and then dried. The polymer was pulverized to a particle size of ~500 µm, and the washing process was repeated. It was then dried in air at 80 °C.

[0032] Example 2

[0033] The difference from Example 1 is that the molar ratio of resorcinol to formaldehyde is adjusted to 1.8:2.2, that is, 330 g of resorcinol and 267 mL of 37% formaldehyde solution.

[0034] The adsorption resin of Example 1 was characterized by FT-IR spectroscopy and SEM. Figure 2 It can be seen that the adsorption resin obtained in Example 1 has a porous structure and good mechanical properties.

[0035] Adsorption kinetics and exchange capacity were tested on the adsorption resin of Example 1. 20 ml of a 20 mg·L⁻¹ cesium solution (pH 10, adjusted by adding ammonia) was added to 0.05 g of adsorbent. The resulting mixture was placed on a shaker and shaken at 300 rpm for different times. After shaking, the adsorbent was filtered, and the concentrations before and after adsorption were determined by flame atomic absorption spectrometry. Typical kinetic curves are shown below. Figure 3 As shown.

[0036] Experimental data can be approximated by two models (Elovich model and Dumwald-Wagne model) to fit the quasi-second-order equations and second-order rate equations. The static exchange rate of cesium, ( The calculation (mg / g) is as follows:

[0037]

[0038] – Initial concentration of cesium, mg·L⁻¹, Ce – Equilibrium concentration of cesium, mg·L⁻¹, – Solution volume, L, m – Mass of adsorbent.

[0039] The average cesium exchange capacity calculated from several batches of adsorbent was found to be 170 mg·g⁻¹.

[0040] Cs adsorption experiments were conducted on Examples 1-2 above in cyclic mode. A single column was packed with resorcinol-formaldehyde resin in the OH- form. 10 L of prepared simulated waste liquid was circulated within the column for 5 hours, with samples taken every hour.

[0041] The waste liquid composition was as follows: initial Cs concentration – 1.0 mg / L, boric acid concentration – 1.5 g / L, pH = 11.0. The target pH was adjusted using a saturated NaOH solution (40% wt.). The Cs concentration in the resulting solution was determined using FAAS. The obtained data are shown in the table below.

[0042] Table 1

[0043] Cycle time / hour Example 1 Cs absorption rate / % Example 2 Cs absorption rate / % 1 98.82 98.20 2 98.99 99.45 3 98.97 99.44 4 99.22 99.53 5 98.44 97.72

[0044] As shown in Table 1, the adsorption resins of Examples 1-2 exhibit a selective adsorption efficiency of over 98% for cesium within 1 hour of circulation and over 99% within 4 hours. The porosity of the resin can be adjusted by regulating the ratio of resorcinol to formaldehyde, thereby regulating the adsorption efficiency. Therefore, the adsorption resin prepared by the method described in this invention is simple to prepare, has good adsorption performance, high mechanical strength, and a selective adsorption efficiency of over 98% for cesium.

[0045] The above description is merely an illustrative embodiment of the present invention and is not intended to limit the scope of the invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the present invention should fall within the scope of protection of the present invention. Furthermore, it should be noted that the components of the present invention are not limited to the overall application described above. Each technical feature described in the specification can be used individually or in combination as needed. Therefore, the present invention naturally covers other combinations and specific applications related to the inventive points of this case.

Claims

1. An adsorption resin for treating cesium-containing wastewater, characterized in that: The resin has the structure of Formula 1: ； Formula 1.

2. A method for preparing an adsorption resin for treating cesium-containing waste liquid, characterized in that: The resin preparation step is as described in Formula 2: ； Formula 2 Specifically, the following steps are included: Step 1: To generate a polymer, resorcinol, formaldehyde, and sodium bicarbonate are dissolved in deionized water, heated, and the pressure is reduced to allow the water to evaporate slowly. After a period of time, a polymer is formed. Step 2: After cooling the solid product overnight, wash it with hydrochloric acid, then soak it in water, and then dry it. Step 3: Crush the polymer, wash it repeatedly, and then dry it to obtain the adsorption resin.

3. The method for preparing an adsorption resin for treating cesium-containing wastewater according to claim 2, characterized in that: In step 1, the mass of resorcinol is 320-350 g, the formaldehyde is a 37% aqueous solution with a volume of 250-280 mL, the mass of sodium bicarbonate is 200-205 g, and the volume of deionized water is 4-5 L.

4. The method for preparing an adsorption resin for treating cesium-containing wastewater according to claim 2, characterized in that: In step 1, the heating temperature is 80-100℃.

5. The method for preparing an adsorption resin for treating cesium-containing wastewater according to claim 2, characterized in that: In step 2, the hydrochloric acid concentration is 0.5 mol / L, and the water immersion time is 2-3 hours.

6. The method for preparing an adsorption resin for treating cesium-containing wastewater according to claim 2, characterized in that: In step 3, the polymer is pulverized to a particle size of 500-1000µm and dried at a temperature of 80-100℃.

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