High-selectivity strontium adsorption material, preparation method and application thereof

Abstract

The application belongs to the technical field of adsorbing materials, and particularly relates to a high-selectivity strontium adsorbing material, a preparation method and application. The preparation method of the high-selectivity strontium adsorbing material comprises the following steps: loading rare earth ions on collagen fibers to obtain an intermediate material; and reacting an oxalate salt and a dimethylamine cation mixed solution with the intermediate material to generate a MOF crystal material with cavities in situ. The application takes dimethylamine cations as exchange ions, and the crystal structure formed by the coordination of rare earth ions and oxalate ions has a cavity size matching the hydrated ion radius of strontium, and has high selectivity to strontium ions, so that the strontium ions can be removed with high selectivity in the presence of various ions.

Description

Technical Field

[0001] This invention belongs to the field of adsorption materials technology, specifically relating to highly selective strontium adsorption materials, their preparation methods, and applications. Background Technology

[0002] Driven by energy demand, nuclear energy, as a cleaner energy source, has developed rapidly. However, while providing convenience, nuclear energy also generates large amounts of wastewater containing radioactive nuclides. Among them, strontium-90 ( 90 Strontium (Sr) is one of the most dangerous radioactive contaminants in the environment, with a half-life of 28 years. Because of its chemical similarity to calcium, Sr readily binds to bones and continues to irradiate local tissues, eventually leading to osteosarcoma and leukemia. Removal of Sr from the aquatic environment is crucial. 2+ It is crucial to prevent harm to the environment and human health. Adsorption and ion exchange are simple and efficient technologies for treating low-level radioactive wastewater, but current strontium ion adsorbents generally suffer from poor selectivity and are easily affected by coexisting ions.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] To address the problems in the background art, the present invention provides a highly selective strontium adsorbent material, its preparation method, and its application.

[0005] To achieve the above objectives, the first technical solution adopted by the present invention is as follows:

[0006] A method for preparing highly selective strontium adsorbent materials includes the following steps:

[0007] Intermediate materials were obtained by loading rare earth ions onto collagen fibers.

[0008] A mixed solution of oxalate and dimethylamine cations was reacted with an intermediate material to generate MOF crystalline material with cavities in situ.

[0009] Preferably, the molar concentration of the oxalate is 0.1-0.50 mmol / L. -1 The concentration of the dimethylamine cation is 0.2-0.6 mmol / L. -1 .

[0010] Preferably, the rare earth ions include yttrium ions, erbium ions, gadolinium ions, holmium ions, and europium ions.

[0011] Preferably, the molar concentration of the rare earth ions is 0.05-0.20 mmol / L. -1 .

[0012] Preferably, the intermediate material is prepared by dispersing collagen fibers in a rare earth ion solution, stirring at room temperature for 0.5-2 hours, adjusting the pH of the solution to 5.0-6.0, reacting at 40-45℃ for 6-12 hours, and then cooling to room temperature.

[0013] Preferably, the method for preparing the cavity-containing MOF crystal material is as follows: a mixed solution of oxalate and dimethylamine cation is slowly added to the intermediate material, the pH of the reaction system is adjusted to 3-7, the mixture is stirred for 0.5-1 h, and then washed and dried.

[0014] Preferably, the collagen fiber is a carboxylated collagen fiber.

[0015] The present invention also discloses highly selective strontium adsorbent materials obtained by any of the preparation methods described above.

[0016] The second technical solution adopted in this invention is:

[0017] Highly selective strontium adsorbent materials are used to remove strontium from water.

[0018] Preferably, continuous column adsorption is used for removal.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. This invention uses dimethylamine cation as the exchange ion and forms a crystal structure through coordination between rare earth ions and oxalate ions. The cavity size matches the hydrated ion radius of strontium, which has high selectivity for strontium ions and can selectively remove strontium ions in the presence of multiple ions.

[0021] 2. After the rare earth oxalate is fixed on the collagen fiber, the material prepared by the present invention is very suitable for continuous column adsorption operation due to the multi-level fiber structure and low mass transfer resistance of the collagen fiber. Attached Figure Description

[0022] Figure 1 The adsorbent material CFs-SA-YOX prepared in Example 2 of this invention exhibits good adsorption properties for Cs when multiple ions coexist. + 、Sr 2+ K + Mg 2+ and Na + Removal rate and separation coefficient;

[0023] Figure 2 The dynamic adsorption performance of the adsorbent material CFs-SA-YOX prepared in Example 2 of this invention on surface water when filled in a packing column. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention. Unless otherwise specified, specific conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0025] The first embodiment of the present invention provides a method for preparing a highly selective strontium adsorbent material, comprising the following steps:

[0026] Intermediate materials were obtained by loading rare earth ions onto collagen fibers.

[0027] A mixed solution of oxalate and dimethylamine cations was reacted with an intermediate material to generate MOF crystalline material with cavities in situ.

[0028] In this embodiment of the invention, dimethylamine cations are used as exchange ions to form crystals through coordination with rare earth ions and oxalate ions. The cavity size of the crystal matches the hydrated ionic radius of strontium, thus exhibiting high selectivity for strontium ions. Even when multiple ions coexist, strontium ions can be removed with high selectivity.

[0029] Individual rare earth oxalate particles are extremely small, making solid-liquid separation difficult after adsorption and resulting in high mass transfer resistance, which is unsuitable for continuous column adsorption operations. However, when immobilized on collagen fibers, the multi-level fiber structure and low mass transfer resistance of the collagen fibers make the prepared adsorbent material highly suitable for continuous column adsorption operations.

[0030] In some preferred embodiments, to further improve the adsorption performance of the adsorbent material, the collagen fiber is carboxylated collagen fiber. Carboxylated collagen fiber uses compounds containing both aldehyde and carboxyl groups, such as dialdehyde polysaccharides. The aldehyde groups of these compounds can covalently bind to the amino groups of the collagen fiber, stably fixing them onto the collagen fiber, while simultaneously increasing the carboxyl content of the collagen fiber, thus carboxylating it. Because rare earth ions have a stronger coordination ability with carboxyl groups, the adsorbent material prepared using carboxylated collagen fiber has a better effect.

[0031] The collagen fibers can be selected from cowhide, sheepskin, pigskin, and other commonly used animal hides.

[0032] Regarding the concentration of rare earth ions, those skilled in the art can choose according to the adsorption effect. The higher the rare earth ion loading, the more MOF crystals are generated in situ, and the better the material's adsorption performance for strontium ions.

[0033] In some preferred embodiments, the molar concentration of the rare earth ions is 0.05-0.20 mmol / L. -1 Commonly used rare earth ions include yttrium ions (Yttrium ions). + ), Erbium ions (Er 3+ ), gadolinium ions (Gd) 3+ ), holmium ions (Ho) 3+ europium ions (Eu) 3+ ).

[0034] Regarding the concentration of oxalate, a low concentration affects its loading on collagen fibers, resulting in a low adsorption capacity; an excessively high concentration can lead to detanning. Therefore, the molar concentration of oxalate is preferably controlled at 0.1-0.50 mmol / L. -1 .

[0035] In some preferred embodiments, the concentration of the dimethylamine cation is 0.2-0.6 mmol / L. -1 .

[0036] In some preferred embodiments, based on the concentration of each of the above raw materials, the amount used is based on the mass of collagen fiber, and can be selected as collagen fiber: rare earth salt: dimethylamine and oxalate mixture = 1g:(20~30)ml:(20~30)ml.

[0037] The specific preparation method for the intermediate material is as follows: Collagen fibers are dispersed in a rare earth ion solution, stirred at room temperature for 0.5-2 hours, the pH of the solution is adjusted to 5.0-6.0, and the reaction is carried out at 40-45℃ for 6-12 hours, followed by cooling to room temperature. This step loads rare earth ions onto the collagen fibers, providing binding sites for the subsequent coordination reaction with oxalate.

[0038] The specific preparation method for MOF crystal materials with cavities can be as follows: a mixed solution of oxalate and dimethylamine cations is slowly added to the intermediate material, the pH of the reaction system is adjusted to 3~7, and after stirring for 0.5~1 h, the material is washed and dried.

[0039] To make the technical solution of the present invention clearer, the adsorption material and its application effects of the present invention will be described in detail below through several specific embodiments.

[0040] Example 1

[0041] 1 g of collagen fibers was dispersed in 20 ml of 0.1 mmol L. -1 In an erbium nitrate solution, the mixture was stirred at room temperature for 0.5 h, then the pH was adjusted to 5.0, and the reaction was carried out at 40 °C for 6 h. After cooling to room temperature, 0.1 mmol L⁻¹ was slowly added. -1 Oxalic acid and 0.2 mmol / L -1A mixed solution of dimethylamine hydrochloride was prepared, the pH of the reaction system was adjusted to 4.0, and the mixture was stirred for 0.5 h. The solution was then washed with deionized water and dried to obtain the adsorbent material CFs-ErOX.

[0042] CFs-ErOX in real lake water (6.2 mg L / L) -1 Sr 2+ 4.6 mg L -1 K + 6.0 mg L -1 Na + 35.7 mg L - 1 Ca 2+ 9.4 mg L -1 Mg 2+ In pH=7.7, for Sr 2+ The removal rate is over 92%.

[0043] Example 2

[0044] 2 g of collagen fibers (CFs) and 1 g of dialdehyde sodium alginate (DSA) were dispersed in 50 ml of deionized water, the pH of the solution was adjusted to 8.0, and the reaction was carried out at 40 °C for 6 h to obtain carboxylated collagen fibers (CFs-SA).

[0045] Disperse CFs-SA g in 60 ml of 0.2 mmol L -1 In a yttrium nitrate solution, the mixture was stirred at room temperature for 1 h, then the pH was adjusted to 6.0, and the reaction was carried out at 45°C for 12 h. After cooling to room temperature, 0.4 mmol L⁻¹ was slowly added. -1 Oxalic acid and 0.5 mmol L -1 A mixed solution of dimethylamine hydrochloride was prepared, the pH of the reaction system was adjusted to 6.0, and the mixture was stirred for 1 h. The solution was then washed with deionized water and dried to obtain the adsorbent material CFs-SA-YOX.

[0046] CFs-SA-YOX contains 8.8 mg L -1 Sr 2+ 43.9 mg L -1 Cs + 62.6 mg L -1 K + 122.5 mg L -1 Na + and 5.8 mg L -1 Mg 2+ In the solution of Sr 2+ The removal rate was still 96.3%, and the separation coefficient was as high as 2.6×10. 4 ,like Figure 1As shown, it exhibits good selectivity. CFs-SA-YOX in real mineral water (6.0 mg / L) -1 Sr 2+ 2.1 mg L -1 K + 0.4 mg / L -1 Na + 6.6 mg L -1 Ca 2+ 2.6 mg L -1 Mg 2+ In pH=7.4), for Sr 2+ The removal rate is over 98%.

[0047] 2 g of CFs-SA-YOX was packed into a 1 cm diameter column with a bed height of 12 cm. The column contained 8.8 mg / L of [a specific substance / component]. -1 Sr 2+ 43.9 mg L -1 Cs + 62.6 mg L -1 K + 122.5 mg L -1 Na + and 5.8 mg L -1 Mg 2+ and 12.0 mg L -1 Ca 2 + The surface water flows at a rate of 0.3 mL / min -1 Through packed columns, its dynamic adsorption performance is as follows: Figure 2 As shown. After 73 hours of system operation, the packing column began to break through, with a treated water volume of 1.305 L. Before the breakthrough, Sr 2+ The removal rates were all above 95%, demonstrating excellent dynamic adsorption performance.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing highly selective strontium adsorbent materials, characterized in that, Includes the following steps: Intermediate materials were obtained by loading rare earth ions onto collagen fibers. A mixed solution of oxalate and dimethylamine cations was reacted with an intermediate material to generate MOF crystalline material with cavities in situ. The rare earth ions include yttrium ions, erbium ions, gadolinium ions, holmium ions, and europium ions.

2. The preparation method according to claim 1, characterized in that, The molar concentration of the oxalate is 0.1-0.50 mmol / L, and the concentration of the dimethylamine cation is 0.2-0.6 mmol / L.

3. The preparation method according to claim 1, characterized in that, The molar concentration of the rare earth ions is 0.05-0.20 mmol / L.

4. The preparation method according to claim 1, characterized in that, The intermediate material is prepared by dispersing collagen fibers in a rare earth ion solution, stirring at room temperature for 0.5-2 hours, adjusting the pH of the solution to 5.0-6.0, reacting at 40-45℃ for 6-12 hours, and then cooling to room temperature.

5. The preparation method according to claim 1, characterized in that, The method for preparing the cavity-containing MOF crystal material is as follows: a mixed solution of oxalate and dimethylamine cation is slowly added to the intermediate material, the pH of the reaction system is adjusted to 3-7, and after stirring for 0.5-1 h, the material is washed and dried.

6. The preparation method according to claim 1, characterized in that, The collagen fibers are carboxylated collagen fibers.

7. A highly selective strontium adsorbent material obtained by any one of the preparation methods described in claims 1-6.

8. The highly selective strontium adsorbent material as described in claim 7 is used to remove strontium from water.

9. The application as described in claim 8, characterized in that, Removal was performed using continuous column adsorption.

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