A method for modifying microporous zeolite using amide podal and its application in adsorbing radionuclides

Abstract

The present invention discloses a method for modifying microporous zeolite using amide pods and its application in adsorbing radioactive nuclides, belonging to the field of radioactive waste treatment. The method of the present invention comprises the following steps: first, pre-treating the microporous zeolite, adding a certain proportion of silane coupling agent to the microporous zeolite molecular sieve, stirring in a constant temperature water bath for a certain period of time, and drying to obtain a product, then adding a certain proportion of amide pods solution to the pre-treated material dropwise, stirring in an ice bath for a period of time, and drying to obtain a modified microporous zeolite. The present invention grafts a linker into the pores of microporous pure silica zeolite in situ, and then grafts an amide ether compound with the linker to achieve solid-liquid adsorption. The method of the present invention has the advantages of simple process, safety and reliability. The modified microporous zeolite prepared by the present invention has the advantages of high stability, high adsorption capacity, high coordination ability, etc.

Description

Technical Field

[0001] The present invention relates to the field of radioactive waste treatment, and in particular to a method for modifying microporous zeolite by utilizing amide podand and an application thereof in adsorbing radioactive nuclides. Background Art

[0002] Amide podal compounds are an important organic extractant with excellent extraction performance for lanthanide and actinide ions. They have attracted particular attention in the research of high-level radioactive liquid waste treatment. They can efficiently separate related ions in the waste liquid and play an important role in the purification of high-level radioactive liquid waste. However, amide podal molecules are toxic and volatile, and are prone to explosion when exposed to open flames. The waste liquid after extraction is also difficult to treat. Microporous pure silicon molecular sieve is an inorganic material with porous properties, a unique crystal structure, and a uniform pore structure. Its special pore structure allows particles of certain specific sizes to remain in the molecular sieve. However, it has an electrically neutral skeleton structure and cannot be directly used for ion adsorption. Therefore, in previous studies, people have used different methods to functionalize and modify pure silicon molecular sieves. The modified molecular sieve composites have shown superior performance.

[0003] With the rapid development of the nuclear energy industry, the amount of spent fuel generated continues to increase. Spent fuel often contains a large number of radioactive nuclides. Due to their long half-lives and strong radioactivity, these nuclides will have serious impacts on the environment if not promptly treated. Therefore, the treatment of radioactive nuclides in high-level liquid waste is crucial to the global ecosystem. In high-level liquid waste treatment systems, the performance of adsorbent materials is a key factor affecting their removal effectiveness.

[0004] Eu in high-level liquid waste 3+ , the method of combining amide podzol and microporous zeolite molecular sieve was chosen to graft amide podzol molecules on the surface of the molecular sieve to prepare an adsorption material with stronger adsorption capacity. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a method for adsorbing radioactive nuclides by using amide pods modified microporous zeolite, which has the characteristics of simple process, energy saving, environmental protection, safety and reliability.

[0006] The present invention discloses a method for modifying microporous zeolite using amide pods, comprising the following steps:

[0007] Step 1: Pretreatment of microporous zeolite: Add the hydrolyzed silane coupling agent solution to the microporous zeolite, stir in a constant temperature water bath, wash and dry;

[0008] Step 2: Modification of microporous zeolite: Add the amide podal solution dropwise to the pretreated microporous zeolite obtained in step 1, stir in an ice bath under alkaline conditions, and dry to obtain the modified microporous zeolite.

[0009] Furthermore, in step 1, the silane coupling agent solution is a mixed solution of a silane coupling agent and toluene; the silane coupling agent is selected from one of propyltrimethoxysilane, propylaminotrimethoxysilane, and aminopropyltriethoxysilane; and the concentration of the silane coupling agent solution is 5% to 15%.

[0010] Furthermore, in step 1, the solid-liquid ratio of the microporous zeolite to the silane coupling agent solution is 1 g: 80-120 mL.

[0011] Furthermore, in step 1, the pretreatment of the microporous zeolite is carried out entirely under a nitrogen atmosphere; the water bath temperature is 30-60°C, the water bath time is 22-28 hours, and the stirring speed is 120-150 r / min; the washing adopts a toluene solution, the drying temperature is 40-60°C, and the drying time is 2-4 hours.

[0012] Furthermore, in step 2, the amide pods solution is a mixed solution of amide pods and toluene, with a concentration of 35% to 50%.

[0013] Furthermore, in step 2, the alkaline environment is created by adding triethylamine, and the solid-liquid ratio of the microporous zeolite to the total solution is 1 g:80-120 mL.

[0014] Furthermore, in step 2, the ice bath temperature is 0-10° C., the ice bath time is 7-10 h, and the stirring speed is 120-150 r / min.

[0015] Furthermore, in step 2, the washing adopts a toluene solution, the drying temperature is 40 to 60° C., and the drying time is 2 to 4 hours.

[0016] The present invention also provides a modified microporous zeolite prepared by the method.

[0017] The present invention also provides a modified microporous zeolite for use in adsorbing radioactive nuclides, specifically, the modified microporous zeolite is fully ground and then added to a solution containing radioactive nuclides, and the reaction is carried out under shaking and stirring at room temperature.

[0018] Furthermore, the radioactive waste liquid produced by nuclear chemical industry is adsorbed by zeolite and converted into solid state, which improves the adsorption capacity of zeolite.

[0019] Furthermore, the modified zeolite has higher stability and adsorption capacity.

[0020] The beneficial effects of the present invention are:

[0021] The present invention has the characteristics of simple process, easy mass production, safety and reliability. Amide-ether compounds have the disadvantages of dependence on organic solvents, complex operation, loss of extractant, difficulty in regeneration and insufficient selectivity in the liquid-liquid extraction of radioactive nuclides, which limit their practical application. The present invention reduces the emulsification phenomenon and loss of extractant, and the pore structure of the zeolite and the grafted amide-ether synergistically improve the adsorption selectivity and stability. The present invention is easy to regenerate, produces less waste, and has a safer solid form, and is suitable for the treatment of highly radioactive waste liquid. The modified microporous zeolite prepared by the present invention has the advantages of high stability, high adsorption capacity, high coordination ability and the like. The method of the present invention has good industrial application prospects. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below in conjunction with specific embodiments. The examples given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0023] The experimental methods in the following examples are conventional methods unless otherwise specified.

[0024] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0025] The zeolite used in the following examples was purchased from the official website of Maclean, and the silane coupling agent used was purchased from the official website of Maclean.

[0026] The method for adsorbing radioactive nuclides by using amidopod ether modified microporous zeolite provided by the present invention comprises the following steps: firstly, pretreating the microporous zeolite, adding a certain proportion of silane coupling agent to the microporous zeolite molecular sieve, stirring in a constant temperature water bath for a certain period of time, and drying to obtain a product, then dropwise adding a certain proportion of amidopod ether solution to the pretreated material, stirring in an ice bath for a period of time, and drying to obtain the modified microporous zeolite.

[0027] In the above-mentioned pretreatment method, the microporous zeolite pretreatment process includes four influencing factors: solid-liquid ratio, preparation temperature, linker concentration, and reaction time.

[0028] The solid-liquid ratio in the above-mentioned pretreatment method is zeolite / connector. In this experiment, toluene is used as the reaction solvent, and the solid-liquid ratio can be 1g:80-120ml.

[0029] The reaction temperature of the above-mentioned pretreatment method is a water bath temperature, which can be 30-60°C.

[0030] In the above-mentioned pretreatment method, the type of linking agent, that is, the type of silane coupling agent used, can be propyltrimethoxysilane, propylaminotrimethoxysilane, or aminopropyltriethoxysilane.

[0031] The concentration of the linking agent in the above-mentioned pretreatment method is a mixed solution of silane coupling agent / silane coupling agent and toluene, which can be 5% to 15%.

[0032] The above pretreatment method needs to be carried out in a nitrogen environment, that is, the gas in the three-necked flask needs to be kept as nitrogen.

[0033] The reaction time of the above-mentioned pretreatment method can be 22 to 28 hours.

[0034] The stirring described in the above pretreatment method needs to be stirred while maintaining the morphology of the granular zeolite, and the stirring speed can be 120-150 r / min.

[0035] After the water bath is completed, the above method needs to be washed, that is, the pretreated zeolite is washed with toluene. The washed microporous zeolite needs to be dried, that is, placed in an oven. The drying temperature and time can be 40-60°C and 2-4h.

[0036] In the above method, the microporous zeolite modification process includes five influencing factors: solid-liquid ratio, modifier concentration, reaction temperature, and reaction time.

[0037] In the above-mentioned microporous zeolite modification process, the solid-liquid ratio is zeolite / total solution volume. In this experiment, toluene is used as the reaction solvent, and the solid-liquid ratio can be 1g:80ml~120ml.

[0038] In the above-mentioned microporous zeolite modification process, the concentration of the modifier is amide pods / a mixed solution of amide pods and toluene, which can be 35%-50%.

[0039] In the above-mentioned microporous zeolite modification process method, the modification reaction time is the time after the modifier is added to the reaction system, which can be specifically 7 hours to 10 hours.

[0040] In the above-mentioned microporous zeolite modification process, the modification reaction temperature is the experimental ice bath temperature, specifically 0-10°C.

[0041] The stirring described in the above-mentioned microporous zeolite modification process method needs to be stirred while maintaining the morphology of the granular zeolite, and the stirring speed can be 120-150 r / min.

[0042] After the water bath is completed, the modified microporous zeolite needs to be washed with toluene. The washed microporous zeolite needs to be dried, that is, placed in an oven. The drying temperature and time can be 40-60°C and 2-4h.

[0043] Example 1

[0044] (1) Using toluene as solvent, 10% N-aminoethyl-γ-propylaminotrimethoxysilane was added to the ground microporous zeolite under nitrogen atmosphere. The mixture was reacted for 24 h in a water bath at 50°C and 130 rpm, then washed, filtered, and dried.

[0045] (2) The pretreated microporous zeolite was placed in a three-necked flask, and toluene was used as the solvent. The ratio of zeolite, toluene, and triethylamine was 0.8 g:40 ml:20 ml. 2,2'-oxodiacetyl chloride solution was added dropwise while stirring in an ice bath below 10°C. The reaction was carried out at 130 r / min for 8 h, followed by washing, filtering, and drying.

[0046] (3) The modified microporous zeolite was fully ground and added to a 1000 ppm Eu(HNO3)3 solution, and the reaction was carried out under shaking and stirring at room temperature for 24 h.

[0047] After testing, the modified microporous zeolite obtained did not undergo significant changes in its structure before and after modification. The adsorption capacity could reach 120 mg / g after 24 hours of reaction in a Eu(HNO3)3 solution with a concentration of 1000 ppm, which was greatly improved compared with the microporous zeolite before modification.

[0048] Example 2

[0049] (1) Using toluene as solvent, 10% 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane was added to the ground microporous zeolite under nitrogen atmosphere. The mixture was reacted for 24 h in a water bath at 50°C and 130 rpm, then washed, filtered, and dried.

[0050] (2) The pretreated microporous zeolite was placed in a three-necked flask, and toluene was used as the solvent. The ratio of zeolite, toluene, and triethylamine was 0.8 g:40 ml:20 ml. 2,2'-oxodiacetyl chloride solution was added dropwise while stirring in an ice bath below 10°C. The reaction was carried out at 130 r / min for 8 h, followed by washing, filtering, and drying.

[0051] (3) The modified microporous zeolite was fully ground and added to a 1000 ppm Eu(HNO3)3 solution, and the reaction was carried out under shaking and stirring at room temperature for 24 h.

[0052] After testing, the zeolite structure of the modified microporous zeolite did not change significantly before and after modification. The adsorption capacity could reach 100 mg / g after 24 hours of reaction in a Eu(HNO3)3 solution with a concentration of 1000 ppm, which was greatly improved compared with the microporous zeolite before modification.

[0053] Example 3

[0054] (1) Using toluene as solvent, 10% 3-aminopropyltriethoxysilane was added to the ground microporous zeolite under nitrogen atmosphere, and the mixture was reacted for 24 hours at 50°C and 130 rpm in a water bath, washed, filtered, and dried.

[0055] (2) The pretreated microporous zeolite was placed in a three-necked flask, and toluene was used as the solvent. The ratio of zeolite, toluene, and triethylamine was 0.8 g:40 ml:20 ml. 2,2'-oxodiacetyl chloride solution was added dropwise while stirring in an ice bath below 10°C. The reaction was carried out at 130 r / min for 8 h, followed by washing, filtering, and drying.

[0056] (3) The modified microporous zeolite was fully ground and added to a 1000 ppm Eu(HNO3)3 solution, and the reaction was carried out under shaking and stirring at room temperature for 24 h.

[0057] After testing, the modified microporous zeolite obtained did not undergo significant changes in its structure before and after modification. The adsorption capacity could reach 110 mg / g after 24 hours of reaction in a Eu(HNO3)3 solution with a concentration of 1000 ppm, which was greatly improved compared with the microporous zeolite before modification.

[0058] Comparative Example 1

[0059] (1) Microporous zeolite was placed in a three-necked flask, and toluene was used as the solvent. The ratio of zeolite, toluene, and triethylamine was 0.8 g:40 ml:20 ml. 2,2'-oxodiacetyl chloride solution was added dropwise while stirring in an ice bath below 10°C. The mixture was reacted at 130 r / min for 8 h, washed, filtered, and dried.

[0060] (2) The modified microporous zeolite was fully ground and added to a 1000 ppm Eu(HNO3)3 solution, and the mixture was stirred and shaken at room temperature for 24 h to react.

[0061] After testing, the adsorption capacity of the microporous zeolite after reacting in a Eu(HNO3)3 solution with a concentration of 1000ppm for 24 hours did not change compared with that of the microporous zeolite before modification.

[0062] Comparative Example 2

[0063] (1) Toluene was used as the solvent, and the ratio of toluene, triethylamine, and 3-aminopropyltriethoxysilane was 50 ml:15 ml:7 ml. 2,2'-oxodiacetyl chloride solution was added dropwise while stirring in an ice bath below 10°C. The mixture was reacted at 130 r / min for 12 h, filtered, and the filtrate was evaporated under reduced pressure at 90°C.

[0064] (2) Using toluene as solvent, the solution obtained by vacuum rotary evaporation in the above step was added to the pretreated microporous zeolite under a nitrogen environment. The ratio of the solution to toluene was 10 ml:100 ml. The mixture was reacted for 24 h in a water bath at 50°C and 130 r / min, and then washed, filtered, and dried.

[0065] (3) The modified microporous zeolite was fully ground and added to a 1000 ppm Eu(HNO3)3 solution, and the reaction was carried out under shaking and stirring at room temperature for 24 h.

[0066] After testing, the modified microporous zeolite obtained did not undergo significant changes in its structure before and after modification. The adsorption capacity after 24 hours of reaction in a Eu(HNO3)3 solution with a concentration of 1000 ppm was 24.59 mg / g, which was greatly reduced compared to the zeolite material modified in the method of the present invention.

[0067] In summary, the microporous zeolite pure silica molecular sieve in the present invention is an inorganic material with porous properties, a unique crystal structure, and a uniform pore structure. Its unique pore structure allows particles of certain specific sizes to be retained within the molecular sieve. However, its electrically neutral framework cannot be directly used for ion adsorption. The present invention effectively overcomes this problem by in-situ grafting a linker into the pores of the microporous pure silica zeolite and then grafting an amide-ether compound onto the linker to achieve solid-liquid adsorption.

[0068] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for modifying microporous zeolite using amide pods, characterized in that: The following steps are involved: Step 1: Pretreatment of microporous zeolite: Add the hydrolyzed silane coupling agent solution to the microporous zeolite, stir in a constant temperature water bath, wash and dry; Wherein, the silane coupling agent solution is a mixed solution of silane coupling agent and toluene; the silane coupling agent is selected from one of propyltrimethoxysilane, propylaminotrimethoxysilane, and aminopropyltriethoxysilane; the concentration of the silane coupling agent solution is 5% to 15%; The solid-liquid ratio of the microporous zeolite to the silane coupling agent solution is 1g:80-120mL; The microporous zeolite is pretreated under a nitrogen atmosphere throughout the entire process; the water bath temperature is 30-60°C, the water bath time is 22-28 hours, and the stirring speed is 120-150 r / min; the washing adopts a toluene solution, the drying temperature is 40-60°C, and the drying time is 2-4 hours; Step 2: Microporous zeolite modification: adding the amide podand solution dropwise to the pretreated microporous zeolite obtained in step 1, stirring in an ice bath under alkaline conditions, and drying to obtain the modified microporous zeolite; Wherein, the amide pods solution is a mixed solution of amide pods and toluene, with a concentration of 35% to 50%; The alkaline environment is prepared by adding triethylamine, and the solid-liquid ratio of the microporous zeolite to the total solution is 1g:80-120mL; The ice bath temperature is 0-10° C., the ice bath time is 7-10 hours, and the stirring speed is 120-150 r / min; the washing adopts a toluene solution, the drying temperature is 40-60° C., and the drying time is 2-4 hours.

2. A modified microporous zeolite prepared according to the method of claim 1.

3. The modified microporous zeolite according to claim 2 is used for adsorbing radionuclides.

4. The use according to claim 3, characterized in that The modified microporous zeolite is fully ground and then added into a solution containing radioactive nuclides, and the reaction is carried out under shaking and stirring at room temperature.