Fluorine removal agent, preparation method thereof and fluorine removal method

Abstract

The invention provides a fluorine removal agent, a preparation method thereof and a fluorine removal method, and relates to the field of sewage treatment. The fluorine removal agent is prepared from the following raw materials in percentage by mass: 10 to 40 percent of modified sepiolite, 30 to 50 percent of modified Y-type molecular sieve and 20 to 40 percent of strongly basic anion exchange resin, wherein the total mass of the raw materials is 100 percent; the modified sepiolite is prepared from the following raw materials: sepiolite, hydrochloric acid and triethylamine; the modified Y-type molecular sieve comprises the following raw materials: a Y-type molecular sieve, 1, 2-propane diamine-N, N, N ', N'-tetraacetic acid and hexadecyl trimethyl ammonium chloride, the use amount of the 1, 2-propane diamine-N, N, N ', N'-tetraacetic acid is 5-10% of the mass of the Y-type molecular sieve, and the use amount of the hexadecyl trimethyl ammonium chloride is 1-5% of the mass of the Y-type molecular sieve. The fluorine removal agent provided by the invention does not contain iron and aluminum elements and can be used for efficiently treating fluorine ions in a water body.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, in particular to a defluoridating agent, a preparation method thereof and a defluoridating method. Background Art

[0002] Excessive fluoride content in water bodies will cause water pollution. Therefore, it is necessary to pay close attention to the fluoride content when treating sewage.

[0003] Current defluoridation methods can be broadly categorized as follows: electrodialysis, precipitation, ion exchange, membrane filtration, and adsorption. The most commonly used method is the use of defluoridation agents. However, existing defluoridation agents often contain iron and aluminum compounds or polymers (such as ferric sulfate, aluminum sulfate, and polyaluminum chloride), which can easily enter water bodies, introducing new sources of pollution and potentially impacting the effectiveness of other treatment processes.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The object of the present invention is to provide a defluorination agent and a preparation method thereof and a defluorination method to solve the above problems.

[0006] In order to achieve the above objectives, the present invention adopts the following technical solutions:

[0007] A defluoridating agent, the raw materials of which, calculated based on the total mass as 100%, include:

[0008] Modified sepiolite 10-40%, modified Y-type molecular sieve 30-50% and strong basic anion exchange resin 20-40%;

[0009] The raw materials of the modified sepiolite include: sepiolite, hydrochloric acid and triethylamine;

[0010] The raw materials of the modified Y-type molecular sieve include Y-type molecular sieve, 1,2-propylenediamine-N,N,N',N'-tetraacetic acid and hexadecyltrimethylammonium chloride, the amount of the 1,2-propylenediamine-N,N,N',N'-tetraacetic acid is 5-10% of the mass of the Y-type molecular sieve, and the amount of the hexadecyltrimethylammonium chloride is 1-5% of the mass of the Y-type molecular sieve.

[0011] Optionally, in the raw materials of the defluoridating agent, the mass proportion of the modified sepiolite can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% or any value between 10-40%; the mass proportion of the modified Y-type molecular sieve can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, 101%, 102%, 103%, 104%, 105%, 106%, 107%, 108%, 109%, 11 % or any value between 30-50%; the mass proportion of the strong basic anion exchange resin can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% or any value between 20-40%; the amount of the 1,2-propylenediamine-N,N,N',N'-tetraacetic acid can be 5%, 6%, 7%, 8%, 9%, 10% or any value between 5-10% of the mass of the Y-type molecular sieve, and the amount of the hexadecyltrimethylammonium chloride can be 1%, 2%, 3%, 4%, 5% or any value between 1-5% of the mass of the Y-type molecular sieve.

[0012] Preferably, the strongly basic anion exchange resin is D201.

[0013] Preferably, the preparation method of the modified sepiolite comprises:

[0014] The sepiolite is mixed with hydrochloric acid, heated and refluxed, and then solid-liquid separated to obtain acid-modified sepiolite;

[0015] The acid-modified sepiolite is mixed with the triethylamine and subjected to organic modification to obtain the modified sepiolite.

[0016] The purpose of hydrochloric acid treatment is to remove impurities. At the same time, acid-modified sepiolite also has a large amount of H + , which facilitates the loading of triethylamine; after modification with triethylamine, the ability of sepiolite to remove fluoride ions is greatly improved.

[0017] Preferably, the temperature of the organic modification is room temperature.

[0018] Preferably, the raw material of the modified sepiolite further includes nano-cerium oxide.

[0019] The addition of nano-cerium oxide is beneficial to improving the ability of modified sepiolite to remove fluoride ions.

[0020] Preferably, the nano-cerium oxide is added to a mixed system of the acid-modified sepiolite and the triethylamine.

[0021] Preferably, the amount of the nano-cerium oxide is 5-10% of the mass of the sepiolite.

[0022] Optionally, the amount of the nano-cerium oxide can be 5%, 6%, 7%, 8%, 9%, 10% or any value between 5% and 10% of the mass of the sepiolite.

[0023] The present application also provides a method for preparing the defluorination agent, comprising:

[0024] The Y-type molecular sieve, the 1,2-propylenediamine-N,N,N',N'-tetraacetic acid and water are mixed, and a first impregnation is performed at room temperature. Then, the hexadecyltrimethylammonium chloride is added, and a second impregnation is performed at a low temperature to obtain a modified Y-type molecular sieve;

[0025] The modified Y-type molecular sieve, the modified sepiolite and the strong alkaline anion exchange resin are mixed to obtain the defluorination agent.

[0026] The weak acidity of 1,2-propylenediamine-N,N,N',N'-tetraacetic acid makes it easy to load into the pores of the Y-type molecular sieve (clean Y-type molecular sieve is weakly alkaline), but it is not stable. If used directly in the impregnation process, the 1,2-propylenediamine-N,N,N',N'-tetraacetic acid will dissolve in water and be carried away by the wastewater during the sewage treatment process. Therefore, it needs to be stabilized first. Because 1,2-propylenediamine-N,N,N',N'-tetraacetic acid is easily soluble in water, hexadecyltrimethylammonium chloride is not used as a conventional surfactant. Instead, its cationic surfactant properties are used to promote the stability of the loaded 1,2-propylenediamine-N,N,N',N'-tetraacetic acid. At the same time, hexadecyltrimethylammonium chloride can also be used as a supplementary material in the sewage treatment process to improve fluoride removal efficiency.

[0027] Preferably, the amount of water added is based on the amount of water needed to immerse the Y-type molecular sieve;

[0028] The low temperature condition corresponds to a temperature of 30-50°C.

[0029] If the temperature is too low, the water solubility of hexadecyltrimethylammonium chloride will be poor; if the temperature is too high, the loading equilibrium between 1,2-propylenediamine-N,N,N',N'-tetraacetic acid and hexadecyltrimethylammonium chloride will be disrupted, and the effect will be worse.

[0030] The time for the first and second immersions is usually 2-24 hours.

[0031] The present application also provides a method for removing fluorine, comprising:

[0032] The defluoridating agent is added to the pretreated fluoride-containing wastewater and allowed to stand.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The defluoridation agent provided in the present application improves sepiolite to enhance its selective adsorption of fluoride ions. The Y-type molecular sieve, 1,2-propylenediamine-N,N,N',N'-tetraacetic acid and hexadecyltrimethylammonium chloride are used in combination. On the one hand, the adsorption capacity of the Y-type molecular sieve is enhanced. On the other hand, the interference of metal ions in the wastewater with the removal of fluoride ions is eliminated by 1,2-propylenediamine-N,N,N',N'-tetraacetic acid; hexadecyltrimethylammonium chloride helps to further enhance the Y-type molecular sieve's ability to remove fluoride ions; and the strong alkaline anion exchange resin can further enhance the defluoridation ability of the defluoridation agent.

[0035] Compared with the prior art using ferric sulfate, aluminum sulfate, and polyaluminum chloride, the defluoridating agent provided by the present application will not significantly increase the iron and aluminum content in water.

[0036] The preparation method of the defluoridating agent provided in the present application comprises first modifying the Y-type molecular sieve and then mixing it with the modified sepiolite, and the preparation is simple.

[0037] The defluorination method provided in this application has high defluorination efficiency. DETAILED DESCRIPTION

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0039] Example 1

[0040] This embodiment provides a defluorination agent, the preparation method of which includes:

[0041] (1) mixing sepiolite with dilute hydrochloric acid (immersing the sepiolite in dilute hydrochloric acid), heating and refluxing, and then filtering to obtain acid-modified sepiolite;

[0042] (2) mixing the acid-modified sepiolite with triethylamine (immersing the sepiolite in triethylamine), performing organic modification, filtering, and naturally drying to obtain modified sepiolite;

[0043] (3) 500 g of Y-type molecular sieve (purchased from Shandong Hefa Environmental Protection Technology Co., Ltd.), 50 g of 1,2-propylenediamine-N,N,N',N'-tetraacetic acid, and water were mixed and impregnated at room temperature. Then, 25 g of hexadecyltrimethylammonium chloride was added and impregnated at 50°C to obtain a modified Y-type molecular sieve;

[0044] The modified Y-type molecular sieve, the modified sepiolite and the strong basic anion exchange resin D201 were mixed in a ratio of 50%, 10% and 40% to obtain a defluorination agent.

[0045] Example 2

[0046] This embodiment provides a defluorination agent, the preparation method of which includes:

[0047] (1) mixing sepiolite with dilute hydrochloric acid (immersing the sepiolite in dilute hydrochloric acid), heating and refluxing, and then filtering to obtain acid-modified sepiolite;

[0048] (2) mixing the acid-modified sepiolite with triethylamine (immersing the sepiolite in triethylamine), performing organic modification, filtering, and naturally drying to obtain modified sepiolite;

[0049] (3) 500 g of Y-type molecular sieve, 25 g of 1,2-propylenediamine-N,N,N',N'-tetraacetic acid, and water were mixed and impregnated at room temperature. Then, 5 g of hexadecyltrimethylammonium chloride was added and impregnated at 30°C to obtain a modified Y-type molecular sieve;

[0050] Modified Y-type molecular sieve, modified sepiolite and strong basic anion exchange resin D201 were mixed in the proportions of 30%, 40% and 30% to obtain a defluoridating agent.

[0051] Example 3

[0052] This embodiment provides a defluorination agent, the preparation method of which includes:

[0053] (1) mixing sepiolite with dilute hydrochloric acid (immersing the sepiolite in dilute hydrochloric acid), heating and refluxing, and then filtering to obtain acid-modified sepiolite;

[0054] (2) mixing the acid-modified sepiolite with triethylamine (immersing the sepiolite in triethylamine), performing organic modification, filtering, and naturally drying to obtain modified sepiolite;

[0055] (3) 500 g of Y-type molecular sieve, 40 g of 1,2-propylenediamine-N,N,N',N'-tetraacetic acid, and water were mixed and impregnated at room temperature. Then, 15 g of hexadecyltrimethylammonium chloride was added and impregnated at 40° C. to obtain a modified Y-type molecular sieve;

[0056] The modified Y-type molecular sieve, the modified sepiolite and the strong basic anion exchange resin D201 were mixed in a ratio of 45%, 35% and 20% to obtain a defluorination agent.

[0057] Example 4

[0058] The difference from Example 1 is that 20-30 μm nano-cerium oxide (purchased from Ningbo Jinlei Nanomaterial Technology Co., Ltd.) is further added in step (2), and the added amount is 5% of the mass of the sepiolite.

[0059] Example 5

[0060] The difference from Example 1 is that the second immersion temperature is 20°C.

[0061] Example 6

[0062] Different from Example 1, the second immersion temperature is 60°C.

[0063] Comparative Example 1

[0064] The difference from Example 1 is that only modified Y-type molecular sieve is used.

[0065] Comparative Example 2

[0066] In contrast to Example 1, only modified sepiolite was used.

[0067] Comparative Example 3

[0068] The difference from Example 1 is that only the strongly basic anion exchange resin D201 is used.

[0069] Comparative Example 4

[0070] The difference from Example 1 is that only modified Y-type molecular sieve and modified sepiolite are used, with a mass ratio of 1:1.

[0071] Comparative Example 5

[0072] The difference from Example 1 is that only modified Y-type molecular sieve and strong basic anion exchange resin D201 are used, with a mass ratio of 1:1.

[0073] Comparative Example 6

[0074] The difference from Example 1 is that only modified sepiolite and strong basic anion exchange resin D201 are used, with a mass ratio of 1:1.

[0075] Comparative Example 7

[0076] The difference from Example 1 is that sepiolite is used instead of modified sepiolite.

[0077] Comparative Example 8

[0078] The difference from Example 1 is that the modified Y-type molecular sieve is replaced by Y-type molecular sieve.

[0079] Comparative Example 9

[0080] The difference from Example 1 is that acid-modified sepiolite is used instead of modified sepiolite.

[0081] Comparative Example 10

[0082] The difference from Example 1 is that cetyltrimethylammonium chloride is not used in the preparation of the modified Y-type molecular sieve.

[0083] Comparative Example 11

[0084] Different from Example 1, 1,2-propylenediamine-N,N,N',N'-tetraacetic acid was not used in the preparation of the modified Y-type molecular sieve.

[0085] A defluorination test was conducted on wastewater from a coking plant (pre-treated to remove solids). The average parameters of the original water sample are shown in Table 1:

[0086] Table 1 Original water sample parameters (unit: mg / L)

[0087]

[0088]

[0089] The defluoridating agents obtained in the Examples and Comparative Examples were added to the wastewater at a rate of 10 g per 100 mg / L of fluoride content. The wastewater was stirred and allowed to stand for 30 minutes. The fluoride content in the treated wastewater was tested, as shown in Table 2 below:

[0090] Table 2 Test data (unit: mg / L)

[0091] project Fluoride content Example 1 0.26 Example 2 0.45 Example 3 0.38 Example 4 0.11 Example 5 1.96 Example 6 1.53 Comparative Example 1 58.41 Comparative Example 2 96.17 Comparative Example 3 204.85 Comparative Example 4 8.66 Comparative Example 5 15.47 Comparative Example 6 47.93 Comparative Example 7 13.71 Comparative Example 8 46.52 Comparative Example 9 30.45 Comparative Example 10 42.84 Comparative Example 11 34.72

[0092] It can be seen from Table 1 that, compared with Example 1, the fluorine content of the treated water sample in Example 4 is further reduced, indicating that the addition of nano-cerium oxide can effectively improve the fluorine removal ability of sepiolite; compared with Example 1, the fluorine content of Comparative Examples 1 to 6 is significantly increased, indicating that there is a certain synergistic effect between the three, and the modified Y-type molecular sieve plays a more important role, and the role of D201 is relatively weak; compared with Example 1, the fluorine content of Comparative Examples 7 to 11 is significantly increased, indicating the importance of modification of sepiolite and Y-type molecular sieve.

[0093] Please note that the technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The above embodiments only express several implementation methods of the present application. The description is relatively specific and detailed, but it cannot be understood as a limitation on the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of this application, several variations and improvements can be made, which all fall within the scope of protection of this application. Therefore, the scope of protection of the patent in this application shall be based on the attached claims.

Claims

1. A defluorination agent, characterized in that: The raw materials are calculated based on the total mass as 100%, including: Modified sepiolite 10-40%, modified Y-type molecular sieve 30-50% and strong basic anion exchange resin 20-40%; The raw materials of the modified sepiolite include: sepiolite, hydrochloric acid and triethylamine; The raw materials of the modified Y-type molecular sieve include Y-type molecular sieve, 1,2-propylenediamine-N,N,N',N'-tetraacetic acid and hexadecyltrimethylammonium chloride, the amount of the 1,2-propylenediamine-N,N,N',N'-tetraacetic acid is 5-10% of the mass of the Y-type molecular sieve, and the amount of the hexadecyltrimethylammonium chloride is 1-5% of the mass of the Y-type molecular sieve.

2. The defluorination agent according to claim 1, wherein The strongly basic anion exchange resin is D201.

3. The defluorination agent according to claim 1, wherein The preparation method of the modified sepiolite comprises: The sepiolite is mixed with hydrochloric acid, heated and refluxed, and then solid-liquid separated to obtain acid-modified sepiolite; The acid-modified sepiolite is mixed with the triethylamine and subjected to organic modification to obtain the modified sepiolite.

4. The defluorination agent according to claim 3, characterized in that The temperature of the organic modification is room temperature.

5. The defluorination agent according to any one of claims 1 to 4, characterized in that The raw materials of the modified sepiolite also include nano-cerium oxide.

6. The defluorination agent according to claim 5, characterized in that The nano-cerium oxide is added into a mixed system of the acid-modified sepiolite and the triethylamine.

7. The defluorination agent according to claim 5, characterized in that The amount of the nano-cerium oxide is 5-10% of the mass of the sepiolite.

8. A method for preparing the defluorination agent according to any one of claims 1 to 7, characterized in that: include: The Y-type molecular sieve, the 1,2-propylenediamine-N,N,N',N'-tetraacetic acid and water are mixed, and a first impregnation is performed at room temperature. Then, the hexadecyltrimethylammonium chloride is added, and a second impregnation is performed at a low temperature to obtain a modified Y-type molecular sieve; The modified Y-type molecular sieve, the modified sepiolite and the strong alkaline anion exchange resin are mixed to obtain the defluorination agent.

9. The method for preparing a defluorinating agent according to claim 8, wherein: The amount of water added is based on the amount of water that can submerge the Y-type molecular sieve; The low temperature condition corresponds to a temperature of 30-50°C.

10. A method for removing fluorine, characterized in that: include: The defluoridating agent is added to the pretreated fluoride-containing wastewater and allowed to stand.

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