A spherical cesium ion adsorbent, a preparation method and application thereof
By preparing spherical cesium ion adsorbents using chitosan, ZIF-8, and nickel ferrocyanide, the problems of low cesium ion adsorption efficiency and high cost in existing technologies have been solved, achieving highly selective and efficient cesium ion adsorption, which is suitable for environmental protection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA UNIV OF PETROLEUM (EAST CHINA)
- Filing Date
- 2024-01-16
- Publication Date
- 2026-06-09
Smart Images
Figure CN117816129B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of adsorption and separation materials technology, specifically to a spherical cesium ion adsorption material, its preparation method, and its application. Background Technology
[0002] The leakage of nuclear waste poses a serious threat to the environment. Among all radioactive pollutants, the leaked radioactive cesium (137Cs) has a half-life of 30.28 years and is the main source of radiation, possessing toxic effects by releasing beta particles and strong gamma rays. Furthermore, cesium ions have high solubility and mobility in the environment, significantly impacting terrestrial and aquatic organisms. Radioactive cesium can also be ingested and accumulated by organisms, undergoing bioaccumulation through the food chain, ultimately posing a threat to humans, leading to cancer, gene mutations, and other diseases. Therefore, from the perspective of protecting the environment and all life on Earth, it is of great significance to efficiently remove and solidify cesium from cesium-containing nuclear waste while minimizing disruption to the original environment. Thus, exploring novel, highly efficient, and environmentally friendly adsorbent materials for radioactive cesium is imperative.
[0003] Currently, common methods for removing cesium from liquid resources include chemical precipitation, solvent extraction, and ion exchange. Among these, ion exchange is widely studied due to its advantages such as high selectivity, simple process, and wide applicability. This invention designs and provides a novel spherical cesium ion adsorbent. This novel spherical cesium ion adsorbent adsorbs cesium ions from cesium-containing aqueous solutions, exhibiting excellent adsorption effect with minimal pH influence. The material is readily available and inexpensive, making it suitable for practical applications. Summary of the Invention
[0004] In view of the problems existing in the prior art, the purpose of this invention is to provide a spherical cesium ion adsorbent, its preparation method and application. The spherical cesium ion adsorbent is low in cost, easy to solidify cesium ions, and has high adsorption capacity and high selectivity for cesium ions.
[0005] To achieve the above objectives, the technical solution provided by the present invention is as follows:
[0006] In a first aspect, the present invention provides a spherical cesium ion adsorbent, wherein the spherical cesium ion adsorbent is a spherical bead with a diameter of 2-2.5 mm and an ordered porous honeycomb structure on the surface, and is made of chitosan, ZIF-8 and nickel ferrocyanide.
[0007] Secondly, the present invention provides a method for preparing a spherical cesium ion adsorbent, the specific preparation process including the following steps:
[0008] Step 1: First, dissolve chitosan in an aqueous acetic acid solution and stir for 3 hours to obtain a chitosan solution. Then, add zinc salt and stir for 5 hours, followed by sonication for 1 hour to obtain a bubble-free zinc salt / chitosan solution.
[0009] Step 2: Using a syringe and an 18G needle, the zinc salt / chitosan solution was dropped into a NaOH solution containing 2-methylimidazole. The mixture was reacted in an oil bath at 80°C for 12 hours. After filtration and washing until neutral, the mixture was freeze-dried for 24 hours to obtain chitosan / ZIF-8 beads.
[0010] Step 3: Immerse the chitosan / ZIF-8 beads prepared in Step 2 in a nickel salt solution for 6 hours, filter and wash, then immerse in a potassium ferrocyanide solution for 12 hours, filter and wash again, and freeze-dry for 24 hours to obtain spherical cesium ion adsorbent.
[0011] As a further technical solution of the present invention, the acetic acid aqueous solution in step one has a mass percentage of 3.2 wt% and a volume of 30 ml-50 ml, and the chitosan solution has a mass percentage of 2 wt%; the zinc salt is one or more of zinc nitrate, zinc chloride, and zinc sulfate, and the zinc salt molar concentration in the zinc salt / chitosan solution is 0.01 mol / L.
[0012] As a further technical solution of the present invention, the concentration of the NaOH solution in step two is 1 mol / L, and the volume is 100 ml-150 ml; the molar mass of 2-methylimidazolium is 0.06 mol-0.07 mol.
[0013] As a further technical solution of the present invention, the nickel salt in step three is one or more of nickel chloride, nickel nitrate, and nickel sulfate, and its solution concentration is 0.05mol / L-0.1mol / L; the concentration of potassium ferrocyanide solution is 0.05mol / L-0.1mol / L.
[0014] Thirdly, the present invention provides an application of a spherical cesium ion adsorbent, wherein the spherical cesium ion adsorbent is mixed with a cesium ion-containing solution under neutral or alkaline conditions for adsorption and separation.
[0015] As a further technical solution of the present invention, the mass ratio of the spherical cesium ion adsorbent to the volume ratio of the cesium ion-containing solution is (0.5-2):1g / L, preferably 0.5:1g / L, 0.6:1g / L, or 0.7:1g / L.
[0016] As a further technical solution of the present invention, the pH range of the neutral or alkaline conditions is 5-11, preferably pH=7; the mixing is carried out in a constant temperature rotary shaker for 22-26 hours, the temperature of the constant temperature rotary shaker is 24-26℃, preferably 24℃, 25℃, or 26℃; the rotation speed of the constant temperature rotary shaker is 150-300 rpm, preferably 160 rpm, 170 rpm, or 180 rpm.
[0017] As a further technical solution of the present invention, the concentration of cesium ions in the cesium-containing solution is 10-200 mg / L.
[0018] As a further technical solution of the present invention, the cesium-containing solution also includes any one or a combination of at least two of potassium chloride, sodium chloride, magnesium chloride, or calcium chloride.
[0019] Compared with existing technologies, this invention uses chitosan, ZIF-8, and nickel ferrocyanide as raw materials. First, chitosan / ZIF-8 beads are prepared by in-situ synthesis. Then, nickel ferrocyanide is loaded onto the chitosan / ZIF-8 beads by impregnation to prepare beads with cesium ion adsorption properties. This method is low in cost, easy to recycle, and can achieve rapid solid-liquid separation after adsorbing cesium ions. It is easy to recover, has high adsorption efficiency, and is suitable for adsorbing low concentrations of cesium ions from cesium-containing aqueous solutions. Attached Figure Description
[0020] Figure 1 The X-ray powder diffraction (XRD) pattern of the spherical cesium ion adsorbent prepared in Example 1 of this invention;
[0021] Figure 2 The image is a scanning electron microscope (SEM) image (1 mm) of the spherical cesium ion adsorbent prepared in Example 1 of the present invention.
[0022] Figure 3 The image shows a scanning electron microscope (SEM) image (30 μm) of the spherical cesium ion adsorbent prepared in Example 1 of this invention.
[0023] Figure 4 The Fourier transform infrared (FT-IR) spectrum of the spherical cesium ion adsorbent prepared in Example 1 of this invention is shown. Detailed Implementation
[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0025] Example 1
[0026] This embodiment provides a method for adsorbing cesium ions, the method comprising the following steps:
[0027] (a) 1 g of chitosan was added to 50 ml of 3 wt% acetic acid aqueous solution, dissolved, and then 10 mmol of zinc nitrate hexahydrate was added. After stirring evenly, the bubbles were removed by ultrasonication to obtain Zn. 2+ / Chitosan mixed solution;
[0028] (b) Prepare 150 ml of 1 mol / L NaOH solution and dissolve it in 50 mmol of 2-methylimidazole. Add the Zn obtained in step (a) 2+ The chitosan mixed solution was dropped into a 2-methylimidazole / NaOH solution using a 10ml syringe and an 18G needle to obtain small beads with a diameter of about 2.5mm. The mixture was reacted in an oil bath at 80℃ for 12h, washed until neutral, and then freeze-dried for 24h to obtain chitosan / ZIF-8 beads.
[0029] (c) The chitosan ZIF-8 beads obtained in step (b) were first soaked in 100 ml of 0.1 mol / L nickel chloride solution for 6 h, washed, and then soaked in 100 ml of 0.1 mol / L potassium ferrocyanide solution. After washing, they were freeze-dried for 24 h to obtain spherical cesium ion adsorbent. The X-ray powder diffraction pattern (XRD), scanning electron microscope (SEM) image (1 mm), scanning electron microscope (SEM) image (30 μm), and Fourier transform infrared (FT-IR) spectrum of the spherical cesium ion adsorbent are shown below. Figure 1-4 As shown;
[0030] (d) The spherical cesium ion adsorbent obtained in step (c) is mixed with a solution containing 100 mg / L Cs at a solid-liquid ratio of 1:2 g / L. + A metal ion solution with pH 8 was mixed at 25°C with stirring until the adsorption equilibrium of the metal ions was reached.
[0031] Example 2
[0032] This embodiment provides a method for adsorbing cesium ions, the method comprising the following steps:
[0033] (a) 1 g of chitosan was added to 50 ml of 3 wt% acetic acid aqueous solution, dissolved, and then 9 mmol of zinc nitrate hexahydrate was added. After stirring evenly, the bubbles were removed by ultrasonication to obtain Zn. 2+ / Chitosan mixed solution;
[0034] (b) Prepare 150 ml of 1 mol / L NaOH solution and dissolve it in 40 mmol of 2-methylimidazole. Add the Zn obtained in step (a) 2+ The chitosan mixed solution was dropped into a 2-methylimidazole / NaOH solution using a 10ml syringe and an 18G needle to obtain small beads with a diameter of about 2.5mm. The mixture was reacted in an oil bath at 80℃ for 12h, washed until neutral, and then freeze-dried for 24h to obtain chitosan / ZIF-8 beads.
[0035] (c) The chitosan ZIF-8 beads obtained in step (b) were soaked in 100 ml of 0.1 mol / L nickel chloride solution for 6 h, washed and then soaked in 100 ml of 0.1 mol / L potassium ferrocyanide solution, washed and then freeze-dried for 24 h to obtain spherical cesium ion adsorbent.
[0036] (d) The spherical cesium ion adsorbent obtained in step (c) is mixed with a solution containing 100 mg / L Cs at a solid-liquid ratio of 1:2 g / L. + A metal ion solution with pH 8 was mixed at 25°C with stirring until the adsorption equilibrium of the metal ions was reached.
[0037] Example 3
[0038] This embodiment provides a method for adsorbing cesium ions, the method comprising the following steps:
[0039] (a) 1 g of chitosan was added to 50 ml of 3 wt% acetic acid aqueous solution, dissolved, and then 11 mmol of zinc nitrate hexahydrate was added. After stirring evenly, the bubbles were removed by sonication to obtain Zn. 2+ / Chitosan mixed solution;
[0040] (b) Prepare 150 ml of 1 mol / L NaOH solution and dissolve it in 60 mmol of 2-methylimidazole. Add the Zn obtained in step (a) 2+ The chitosan mixed solution was dropped into a 2-methylimidazole / NaOH solution using a 10ml syringe and an 18G needle to obtain small beads with a diameter of about 2.5mm. The mixture was reacted in an oil bath at 80℃ for 12h, washed until neutral, and then freeze-dried for 24h to obtain chitosan / ZIF-8 beads.
[0041] (c) The chitosan ZIF-8 beads obtained in step (b) were soaked in 100 ml of 0.1 mol / L nickel chloride solution for 6 h, washed and then soaked in 100 ml of 0.1 mol / L potassium ferrocyanide solution, washed and then freeze-dried for 24 h to obtain spherical cesium ion adsorbent.
[0042] (d) The spherical cesium ion adsorbent obtained in step (c) is mixed with a solution containing 100 mg / L Cs at a solid-liquid ratio of 1:2 g / L. + A metal ion solution with pH 8 was mixed at 25°C with stirring until the adsorption equilibrium of the metal ions was reached.
[0043] Example 4
[0044] This embodiment provides a method for adsorbing cesium ions. Except for step (d), where the pH of the mixture is 3, the method is the same as in Example 1.
[0045] Example 5
[0046] This embodiment provides a method for adsorbing cesium ions. Except for step (d), where the pH of the mixture is 4, the method is the same as in Example 1.
[0047] Example 6
[0048] This embodiment provides a method for adsorbing cesium ions. Except for step (d), where the pH of the mixture is 5, the method is the same as in Example 1.
[0049] Example 7
[0050] This embodiment provides a method for adsorbing cesium ions. Except for step (d), where the pH of the mixture is 6, the method is the same as in Example 1.
[0051] Example 8
[0052] This embodiment provides a method for adsorbing cesium ions. Except for step (d), where the pH of the mixture is 7, the method is the same as in Example 1.
[0053] Example 9
[0054] This embodiment provides a method for adsorbing cesium ions. Except for step (d), where the pH of the mixture is 8, the method is the same as in Example 1.
[0055] Example 10
[0056] This embodiment provides a method for adsorbing cesium ions. Except for step (d), where the pH of the mixture is 9, the method is the same as in Example 1.
[0057] Example 11
[0058] This embodiment provides a method for adsorbing cesium ions. Except for step (d), where the pH of the mixture is 10, the method is the same as in Example 1.
[0059] Example 12
[0060] This embodiment provides a method for adsorbing cesium ions. Except for step (d), where the pH of the mixture is 11, the method is the same as in Example 1.
[0061] Example 13
[0062] This embodiment provides a method for adsorbing cesium ions. Except for step (d), in which potassium ions are added to the mixed solution at a concentration of 100 mg / L, the method is the same as in Example 1.
[0063] Example 14
[0064] This embodiment provides a method for adsorbing cesium ions. Except for step (d), in which sodium ions are added to the mixed solution at a concentration of 100 mg / L, the method is the same as in Example 1.
[0065] Example 15
[0066] This embodiment provides a method for adsorbing cesium ions. Except for step (d), in which calcium ions are added to the mixed solution at a concentration of 100 mg / L, the method is the same as in Example 1.
[0067] Example 16
[0068] This embodiment provides a method for adsorbing cesium ions. Except for step (d), in which magnesium ions are added to the mixed solution at a concentration of 100 mg / L, the method is the same as in Example 1.
[0069] Comparative Example 1
[0070] This embodiment provides a method for adsorbing cesium ions. Except for the mixing temperature of step (d) being 35°C, the method is the same as that in Example 1.
[0071] Comparative Example 2
[0072] This embodiment provides a method for adsorbing cesium ions. Except for the mixing temperature of step (d) being 45°C, the method is the same as that in Example 1.
[0073] This embodiment uses inductively coupled plasma optical emission spectrometry (ICP-AES) to determine the concentration of cesium ions in the solution and calculates the adsorption amount of cesium ions. Where C0 (mg / L) is the initial concentration of metal ions, C e (mg / L) is the concentration of metal ions in the solution at adsorption equilibrium, V(L) is the solution volume, and m(g) is the mass of adsorbent added; the results are shown in Table 1 and Table 2.
[0074] Table 1:
[0075] Cs+ adsorption capacity (mg / g) Experimental Case 1 65.73 Experimental Case 2 58.49 Experimental Case 3 54.3 Experimental Case 4 50.362 Experimental Case 5 57.20673 Experimental Case 6 64.3746 Experimental Case 7 64.81233 Experimental Case 8 64.62407 Experimental Case 9 64.6454 Experimental Case 10 64.33133 Experimental Case 11 65.4894 Experimental Case 12 64.86113 Comparison Case 1 71.3356 Comparison Case 2 74.432
[0076] Examples 1-12 and Comparative Examples 1 and 2 on Cs + The adsorption results are shown in Table 1. As can be seen from Table 1, the spherical cesium ion adsorbent prepared in this embodiment exhibits good adsorption performance for Cs. + The adsorption capacity can reach 65.73 mg / g;
[0077] A comparison of Examples 2 and 3 with Example 1 shows that both insufficient and excessive ZIF-8 content in the beads will affect the adsorbent's effect on Cs. +The adsorption of ZIF-8 is affected by the fact that too little ZIF-8 will affect the saturation of the bead material, while too much ZIF-8 will affect the viscosity of chitosan and thus affect the adsorption performance of the material.
[0078] As can be seen from the comparison of Examples 4-12, and because it can maintain good adsorption performance in the pH range of 5-11, it is because H+ at low pH... + Excessive influence on the adsorbent's effect on Cs + Adsorption performance;
[0079] As can be seen from Example 1 and Comparative Examples 2 and 3, with the increase of mixing temperature, the spherical adsorbent for Cs... + The increased adsorption capacity indicates that the material has good adhesion to Cs. + Adsorption is an endothermic reaction.
[0080] Table 2:
[0081] Cs+ adsorption capacity (mg / g) Interfering ion adsorption capacity (mg / g) Experimental Case 13 60 -62.4 Experimental Case 14 62.03333 2.81 Experimental Case 15 62.27 2.73 Experimental Case 16 62.7 1.69
[0082] Table 2 shows that the spherical cesium ion adsorbent has a lower effect on Cs in the presence of other cation interferences. + The adsorption capacity of the spherical adsorbent is not significantly affected, and the adsorption capacity of interfering cations K, Na, Mg, and Ca is very small, indicating that the spherical adsorbent has little effect on Cs. + It exhibits high selectivity, with K before and after adsorption. + The increase in K+ content and the negative adsorption value are due to the involvement of K+ on the adsorbent during the adsorption process. + With Cs in solution + Ion exchange is performed.
[0083] In summary, the spherical cesium ion adsorbent provided by this invention achieves both the adsorption of Cs ions and the removal of spherical cesium ions. + It has a high adsorption capacity and high cesium ion selectivity, and the preparation method is simple, the materials are readily available, the cost is low and it is environmentally friendly.
[0084] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
[0085] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A method for preparing a spherical cesium ion adsorbent, characterized in that, The specific preparation process includes the following steps: Step 1: First, dissolve chitosan in an aqueous acetic acid solution and stir for 3 hours to obtain a chitosan solution. Then, add zinc salt and stir for 5 hours, followed by sonication for 1 hour to obtain a bubble-free zinc salt / chitosan solution. Step 2: Using a syringe and an 18G needle, the zinc salt / chitosan solution was dropped into a NaOH solution containing 2-methylimidazole. The mixture was reacted in an oil bath at 80°C for 12 hours. After filtration and washing until neutral, the mixture was freeze-dried for 24 hours to obtain chitosan / ZIF-8 beads. Step 3: Immerse the chitosan / ZIF-8 beads prepared in Step 2 in a nickel salt solution for 6 hours, filter and wash, then immerse in a potassium ferrocyanide solution for 12 hours, filter and wash again, and freeze-dry for 24 hours to obtain a spherical cesium ion adsorbent. The prepared spherical cesium ion adsorbent consists of beads with a diameter of 2-2.5 mm and an ordered porous honeycomb structure on the surface.
2. The method for preparing the spherical cesium ion adsorbent according to claim 1, characterized in that, In step one, the acetic acid aqueous solution contains 3.2 wt% acetic acid and has a volume of 30 ml to 50 ml. The chitosan solution contains 2 wt% chitosan. The zinc salt is one or more of zinc nitrate, zinc chloride, and zinc sulfate. The molar concentration of zinc salt in the zinc salt / chitosan solution is 0.01 mol / L.
3. The method for preparing the spherical cesium ion adsorbent according to claim 2, characterized in that, The NaOH solution in step two has a concentration of 1 mol / L and a volume of 100 ml to 150 ml; the molar amount of 2-methylimidazole is 0.06 mol to 0.07 mol.
4. The method for preparing the spherical cesium ion adsorbent according to claim 2, characterized in that, The nickel salt mentioned in step three is one or more of nickel chloride, nickel nitrate, and nickel sulfate, with a solution concentration of 0.05 mol / L to 0.1 mol / L; the potassium ferrocyanide solution concentration is 0.05 mol / L to 0.1 mol / L.
5. The application of a spherical cesium ion adsorbent prepared by the method described in claim 1, characterized in that, Adsorption and separation are carried out by mixing spherical cesium ion adsorbent with cesium ion-containing solution under conditions of pH range 5-11; the mass ratio of the spherical cesium ion adsorbent to the volume ratio of the cesium ion-containing solution is (0.5-2):1 g / L; the cesium ion concentration in the cesium ion-containing solution is 10-200 mg / L.
6. The application of the spherical cesium ion adsorbent according to claim 5, characterized in that, The mixing is carried out in a constant temperature rotary shaker for 22-26 hours, with the temperature of the constant temperature rotary shaker being 24-26°C and the rotation speed of the constant temperature rotary shaker being 150-300 rpm.
7. The application of the spherical cesium ion adsorbent according to claim 5, characterized in that, The cesium-containing solution also includes any one or a combination of at least two of potassium chloride, sodium chloride, magnesium chloride, or calcium chloride.