Method for modifying microporous zeolite by using amido podand and application of amido podand to adsorption of radionuclides

Abstract

The invention discloses a method for modifying microporous zeolite by using amido podand and application of the modified microporous zeolite in adsorbing radionuclides, and belongs to the field of radioactive waste treatment. The method of the invention comprises the following steps; the preparation method comprises the following steps: firstly, pretreating microporous zeolite, adding a certain proportion of a silane coupling agent into a microporous zeolite molecular sieve, stirring for a certain time in a constant-temperature water bath, drying to obtain a product, dropwise adding the pretreated material into a certain proportion of an amido pod ether solution, stirring for a period of time in an ice bath, and drying to obtain the modified microporous zeolite. According to the invention, the coupling agent is grafted into the pore channel of the microporous pure silica zeolite in situ, and then the amide ether compound is grafted with the coupling agent to realize solid-liquid adsorption. The method has the advantages of being simple in technological process, safe, reliable and the like. The prepared modified microporous zeolite has the advantages of high stability, high adsorption capacity, high coordination capability and the like.

Description

Technical Field

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

[0002] Amide podoid compounds are an important organic extractant with excellent extraction performance for lanthanide and actinide ions. They have attracted special attention in the research of high-level radioactive waste liquid treatment. They can efficiently separate related ions in waste liquid and play an important role in purifying high-level radioactive waste liquid. However, amide podoid molecules are toxic and volatile, and are prone to explosion when exposed to open flames. The waste liquid after extraction is also difficult to handle. Microporous pure silicon molecular sieve is an inorganic material with porous properties, unique crystal structure and uniform pore structure. Its special pore structure allows certain particles of 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 functionally modify pure silicon molecular sieves, and the modified molecular sieve composites have shown superior performance.

[0003] With the rapid development of the nuclear energy industry, the amount of spent fuel is increasing. Spent fuel often contains a large amount of radioactive nuclides. Due to their long half-life and strong radioactivity, if they are not treated in time, these nuclides will have a serious impact on the environment. Therefore, the treatment of radioactive nuclides in high-level liquid waste is crucial to the global ecosystem. In the high-level liquid waste treatment system, the performance of the adsorption material is the key factor affecting its removal effect.

[0004] Targeting Eu in high-level liquid waste 3+ , a method of combining amide pods with microporous zeolite molecular sieves was selected to graft amide pods molecules on the surface of the molecular sieve to prepare an adsorption material with stronger adsorption capacity. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for adsorbing radioactive nuclides by using amide pod ether 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 by using amide pod ether, comprising the following steps:

[0007] Step 1: Pretreatment of microporous zeolite: Add 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 pod ether solution dropwise to the pretreated microporous zeolite obtained in step 1, stir in an ice bath under alkaline environment, and obtain the modified microporous zeolite after drying.

[0009] Furthermore, in step 1, 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; 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 22-28h, and the stirring speed is 120-150r / min; the washing adopts a toluene solution, the drying temperature is 40-60°C, and the drying time is 2-4h.

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

[0013] Furthermore, in step 2, the alkaline environment is prepared 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 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, which is specifically added to a solution containing radioactive nuclides after being fully ground, and reacted under oscillation 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, convenient 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 liquid-liquid extraction of radionuclides, which limits their practical application. The present invention reduces the emulsification phenomenon and loss of extractant, and the pore structure of zeolite and the grafted amide-ether synergistically improve the adsorption selectivity and stability. The present invention is easy to regenerate, generates less waste, and has a safer solid form, which 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 is further described in detail below in conjunction with specific embodiments. The examples given are only for illustrating the present invention, not for limiting the scope of the present invention.

[0023] The experimental methods in the following examples are all 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 Maclean official website, and the silane coupling agent used was purchased from the Maclean official website.

[0026] The method for adsorbing radioactive nuclides by using amide pods modified microporous zeolite provided by the present invention comprises the following steps: firstly, 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, and then adding a certain proportion of amide pods solution dropwise to the pre-treated 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 the linking agent is the type of silane coupling agent used, which can be propyltrimethoxysilane, propylaminotrimethoxysilane, or aminopropyltriethoxysilane.

[0031] The concentration of the connecting 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 pretreatment method can be 22 to 28 hours.

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

[0035] After the water bath in the above method is finished, washing is required, that is, toluene is used to wash the pretreated zeolite. 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 2-4 hours.

[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 method, the solid-liquid ratio is zeolite / total volume of solution. 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 method, 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 into the reaction system, which can be specifically 7h to 10h.

[0040] In the above-mentioned microporous zeolite modification process method, 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 in the above method is finished, washing is required, that is, toluene is used to wash the modified microporous zeolite. The washed microporous zeolite needs to be dried, that is, placed in an oven, and the drying temperature and time can be 40-60° C. and 2-4 hours.

[0043] Example 1

[0044] (1) Using toluene as solvent, 10% N-aminoethyl-γ-propylaminotrimethoxysilane was added to the ground microporous zeolite under nitrogen environment, and the mixture was reacted for 24 hours at 50° C. and 130 r / min in a water bath thermostat, 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 at a temperature below 10° C. under ice bath stirring. The reaction was carried out at 130 r / min for 8 h, and then the zeolite was washed, filtered and dried.

[0046] (3) The modified microporous zeolite was fully ground and added to a concentration of 1000 ppm Eu(HNO 3 ) 3 The solution was stirred and shaken at room temperature for 24 h to react.

[0047] The test showed that the structure of the modified microporous zeolite did not change significantly before and after modification. 3 ) 3 The adsorption capacity can reach 120 mg / g after 24 hours of reaction in the solution, which is 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 environment, and the mixture was reacted for 24 hours at 50° C. and 130 r / min in a water bath thermostat, and 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 at a temperature below 10° C. under ice bath stirring. The reaction was carried out at 130 r / min for 8 h, and then the zeolite was washed, filtered and dried.

[0051] (3) The modified microporous zeolite was fully ground and added to a concentration of 1000 ppm Eu(HNO 3 ) 3 The solution was stirred and shaken at room temperature for 24 h to react.

[0052] The results showed that the modified microporous zeolite had no significant changes in structure before and after modification. 3 ) 3The adsorption capacity can reach 100 mg / g after 24 hours of reaction in the solution, which is 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 environment, and the mixture was reacted for 24 hours at 50° C. and 130 r / min in a water bath thermostat, then 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 at a temperature below 10° C. under ice bath stirring. The reaction was carried out at 130 r / min for 8 h, and then the zeolite was washed, filtered and dried.

[0056] (3) The modified microporous zeolite was fully ground and added to a concentration of 1000 ppm Eu(HNO 3 ) 3 The solution was stirred and shaken at room temperature for 24 h to react.

[0057] The test showed that the structure of the modified microporous zeolite did not change significantly before and after modification. 3 ) 3 The adsorption capacity can reach 110 mg / g after 24 hours of reaction in the solution, which is greatly improved compared with the microporous zeolite before modification.

[0058] Comparative Example 1

[0059] (1) The microporous zeolite is placed in a three-necked flask, and toluene is used as the solvent. The ratio of zeolite, toluene and triethylamine is 0.8 g:40 ml:20 ml. When stirred in an ice bath below 10°C, 2.5 ml of 2,2'-oxodiacetyl chloride solution is added dropwise. The mixture is reacted at 130 r / min for 8 h, and then washed, filtered and dried.

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

[0061] After testing, in the presence of 1000ppm Eu(HNO 3 ) 3 The adsorption capacity of the microporous zeolite in the solution after 24 hours of reaction 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 at a temperature below 10°C under ice-bath stirring. 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, add the solution obtained by vacuum rotary evaporation in the above step to the pretreated microporous zeolite under nitrogen environment, the ratio of solution to toluene is 10ml:100ml, react in a water bath thermostat at 50°C and 130r / min for 24h, wash, filter and dry.

[0065] (3) The modified microporous zeolite was fully ground and added to a concentration of 1000 ppm Eu(HNO 3 ) 3 The solution was stirred and shaken at room temperature for 24 h to react.

[0066] The test showed that the structure of the modified microporous zeolite did not change significantly before and after modification. 3 ) 3 The adsorption capacity after 24 h of reaction in the solution is 24.59 mg / g, which is greatly reduced compared with the zeolite material modified in the method of the present invention.

[0067] In summary, the microporous zeolite pure silicon molecular sieve in the present invention is an inorganic material with porous properties, unique crystal structure and uniform pore structure. Its special pore structure allows certain particles of specific size to stay in the molecular sieve. However, it has an electrically neutral skeleton structure and cannot be directly used for ion adsorption. The present invention grafts the linker in situ into the microporous pure silicon zeolite pores, and then grafts the amide-ether compound with the linker to achieve solid-liquid adsorption, which can effectively overcome the above problems.

[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 principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for modifying microporous zeolite using amide pod ether, characterized in that: The following steps are involved: Step 1: Pretreatment of microporous zeolite: Add hydrolyzed silane coupling agent solution to the microporous zeolite, stir in a constant temperature water bath, wash and dry; Step 2: modification of microporous zeolite: add the amide pod ether solution dropwise to the pretreated microporous zeolite obtained in step 1, stir in an ice bath under alkaline environment, and obtain the modified microporous zeolite after drying.

2. The method for modifying microporous zeolite using amide pod ether according to claim 1, characterized in that: In step 1, 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; and the concentration of the silane coupling agent solution is 5% to 15%.

3. The method for modifying microporous zeolite using amide pod ether according to claim 1, characterized in that: In step 1, the solid-liquid ratio of the microporous zeolite to the silane coupling agent solution is 1 g: 80-120 mL.

4. The method for modifying microporous zeolite using amide pod ether according to claim 1, characterized in that: In step 1, the pretreatment of the microporous zeolite is carried out under a nitrogen atmosphere throughout the process; the water bath temperature is 30-60°C, the water bath time is 22-28h, and the stirring speed is 120-150r / min; the washing adopts a toluene solution, the drying temperature is 40-60°C, and the drying time is 2-4h.

5. The method for modifying microporous zeolite using amide pod ether according to claim 1, characterized in that: In step 2, the amide pod ether solution is a mixed solution of amide pod ether and toluene, with a concentration of 35% to 50%.

6. The method for modifying microporous zeolite using amide pod ether according to claim 1, characterized in that: In step 2, the alkaline environment is formed by adding triethylamine, and the solid-liquid ratio of the microporous zeolite to the total solution is 1 g: 80-120 mL.

7. The method for modifying microporous zeolite using amide pod ether according to claim 1, characterized in that: 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; the washing adopts a toluene solution, the drying temperature is 40-60° C., and the drying time is 2-4 h.

8. A modified microporous zeolite prepared according to any one of claims 1 to 7.

9. The modified microporous zeolite according to claim 8 is used for adsorbing radionuclides.

10. The use according to claim 9, characterized in that: The modified microporous zeolite is fully ground and added into a solution containing radioactive nuclides, and the reaction is carried out under shaking and stirring at room temperature.