A fluoride removal agent for wastewater and its preparation method

Abstract

This invention relates to the field of defluoridation technology, and proposes a defluoridating agent for wastewater and its preparation method. The wastewater defluoridating agent comprises the following components by weight: 40-60 parts of polyaluminum ferric chloride, 5-10 parts of sodium carboxymethyl cellulose, 2-20 parts of ferric ammonium ethylenediaminetetraacetate, 5-20 parts of sodium lauryl phosphate, 5-15 parts of ethylenediaminetetraacetic acid, 1-10 parts of polyethylene glycol, and 200-240 parts of water. This technical solution solves the problem of low defluoridation rate in existing wastewater defluoridating agents.

Description

Technical Field

[0001] This invention relates to the field of defluoridation technology, specifically to a defluoridation agent for wastewater and its preparation method. Background Technology

[0002] With rapid industrial development, the fluoride content in wastewater discharged from industries such as aluminum electrolysis, steel, phosphate fertilizer, glass, ceramics, and electronics is increasing daily. Simultaneously, in certain geological areas, groundwater may naturally contain high concentrations of fluoride ions. If this fluoride-containing wastewater is discharged directly without effective treatment, it will pose a serious threat to the ecological environment and human health.

[0003] Fluorine is an essential trace element for the human body, but excessive intake can lead to diseases such as dental fluorosis and skeletal fluorosis, affecting the normal development and function of bones and teeth. Environmentally, high concentrations of fluoride ions can negatively impact aquatic ecosystems, interfering with the normal physiological metabolism and reproduction of aquatic organisms and disrupting the ecological balance of water bodies. Traditional fluoride removal methods include precipitation, adsorption, and ion exchange, but these methods often have limitations. Precipitation is not ideal for removing low concentrations of fluoride ions and produces large amounts of sludge; adsorption methods involve difficult and costly adsorbent regeneration; and ion exchange methods have strict requirements for influent water quality and are complex to operate.

[0004] In summary, existing wastewater defluoridation agents have low defluorination rates; therefore, developing highly efficient wastewater defluoridation agents is of significant practical importance. Summary of the Invention

[0005] This invention proposes a defluoridating agent for wastewater and its preparation method, which solves the problem of low defluoridation rate of defluoridating agents for wastewater in related technologies.

[0006] The technical solution of the present invention is as follows: This invention proposes a fluoride removal agent for wastewater, the raw materials of which include the following components by weight: 40-60 parts of polyaluminum ferric chloride, 5-10 parts of sodium carboxymethyl cellulose, 2-20 parts of ferric ammonium ethylenediaminetetraacetate, 5-20 parts of sodium lauryl phosphate, 5-15 parts of ethylenediaminetetraacetic acid, 1-10 parts of polyethylene glycol, and 200-240 parts of water.

[0007] As a further technical solution, the mass ratio of the ferric ammonium ethylenediaminetetraacetate to the sodium lauryl phosphate is 0.5~1.5:1.

[0008] This invention further improves the defluorination rate of wastewater defluorinating agents by adjusting the mass ratio of ferric ammonium ethylenediaminetetraacetate to sodium lauryl phosphate to 0.5~1.5:1.

[0009] As a further technical solution, the mass ratio of ferric ammonium ethylenediaminetetraacetate to sodium lauryl phosphate is 1:1.

[0010] This invention further improves the defluorination rate of wastewater defluorinating agents by adjusting the mass ratio of ferric ammonium ethylenediaminetetraacetate to sodium lauryl phosphate to 1:1.

[0011] As a further technical solution, the mass ratio of ethylenediaminetetraacetic acid to polyethylene glycol is 1~3:1.

[0012] This invention further improves the defluorination rate of wastewater defluorinating agents by adjusting the mass ratio of ethylenediaminetetraacetic acid to polyethylene glycol to 1~3:1.

[0013] As a further technical solution, the mass ratio of ethylenediaminetetraacetic acid to polyethylene glycol is 2:1.

[0014] This invention further improves the defluorination rate of wastewater defluorinating agents by adjusting the mass ratio of ethylenediaminetetraacetic acid to polyethylene glycol to 2:1.

[0015] As a further technical solution, the basicity of the polyaluminum ferric chloride is 60%~90%.

[0016] As a further technical solution, the polyethylene glycol includes one of PEG-800, PEG-1000, and PEG-1500.

[0017] As a further technical solution, the polyethylene glycol is PEG-1000.

[0018] This invention also proposes a method for preparing a defluoridating agent for wastewater, comprising the following steps: S1. Dissolve polyaluminum ferric chloride in water, add sodium carboxymethyl cellulose to obtain the first mixture; S2. After mixing ferric ammonium ethylenediaminetetraacetate and sodium lauryl phosphate, add the first mixture and dissolve to obtain the second mixture; S3. Add ethylenediaminetetraacetic acid and polyethylene glycol to the second mixture, mix well, and obtain a defluorinating agent.

[0019] As a further technical solution, the dissolution temperature in S2 is 35~55℃.

[0020] The working principle and beneficial effects of this invention are as follows: In this invention, polyaluminum ferric chloride (PAFC) serves as a key raw material for defluorination. The various high-valence polynuclear ions generated during its hydrolysis can complex with fluoride ions, causing them to precipitate or be adsorbed onto the surface of its hydrolysis products, thus effectively removing fluoride ions from wastewater. Furthermore, compared to single aluminum or iron salts, PACFC exhibits wider pH adaptability and better coagulation effects when treating complex water qualities, thereby increasing the defluorination rate. Sodium carboxymethyl cellulose (CMC) increases the viscosity of the solution during defluorination, allowing other defluorination components to disperse better in the wastewater, ensuring a more uniform and thorough defluorination reaction. Simultaneously, the carboxyl groups in its molecular structure possess certain adsorption properties, enabling weak interactions with fluoride ions, assisting other key defluorination components and enhancing the overall defluorination effect. The synergistic combination of ferric ammonium ethylenediaminetetraacetate (EDTA) and sodium lauryl phosphate further improves the defluorination effect of wastewater defluorination agents. Ethylenediaminetetraacetic acid (EDTA) possesses strong chelating ability, forming stable chelates with various metal ions. During defluorination, it can chelate with potentially interfering metal ions (such as calcium, magnesium, and iron) in wastewater, preventing these metal ions from forming difficult-to-remove complexes with fluoride ions. This reduces interference with the defluorination process, allowing the defluorinating agent to act more effectively on fluoride ions. Polyethylene glycol (PEG) has good water solubility and dispersibility, improving the solubility and dispersion of each component of the defluorinating agent in wastewater, ensuring sufficient contact between each component and fluoride ions, and increasing reaction efficiency. The synergistic effect of EDTA and PEG enhances the defluorination rate of wastewater defluorinating agents. Detailed Implementation

[0021] 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] In the following examples and comparative examples, the basicity of polyaluminum ferric chloride is 90%, and the manufacturer is Zhengzhou Chuangshi Water Purification Materials Co., Ltd.; the viscosity of sodium carboxymethyl cellulose is 3100 mPa·s, the degree of substitution is 0.92, and the content is 99.7 wt%; the content of ferric ammonium ethylenediaminetetraacetate is 98 wt%, the content of sodium lauryl phosphate is 98 wt%, the content of ethylenediaminetetraacetic acid is 98 wt%, and the polyethylene glycol is PEG-1000.

[0023] Example 1 A wastewater defluoridating agent comprises the following components by weight: 60 parts polyaluminum ferric chloride, 10 parts sodium carboxymethyl cellulose, 2 parts ferric ammonium ethylenediaminetetraacetate, 20 parts sodium lauryl phosphate, 5 parts ethylenediaminetetraacetic acid, 10 parts polyethylene glycol, and 240 parts water. Its preparation method includes the following steps: S1. Dissolve polyaluminum ferric chloride in water, add sodium carboxymethyl cellulose to obtain the first mixture; S2. After mixing ferric ammonium ethylenediaminetetraacetate and sodium lauryl phosphate, add the first mixture and dissolve at 55°C to obtain the second mixture. S3. Add ethylenediaminetetraacetic acid and polyethylene glycol to the second mixture, mix well, and obtain the defluorinating agent.

[0024] Example 2 A wastewater defluoridating agent comprises the following components by weight: 40 parts polyaluminum ferric chloride, 5 parts sodium carboxymethyl cellulose, 20 parts ferric ammonium ethylenediaminetetraacetic acid, 5 parts sodium lauryl phosphate, 15 parts ethylenediaminetetraacetic acid, 1 part polyethylene glycol, and 200 parts water. Its preparation method includes the following steps: S1. Dissolve polyaluminum ferric chloride in water, add sodium carboxymethyl cellulose to obtain the first mixture; S2. After mixing ferric ammonium ethylenediaminetetraacetate and sodium lauryl phosphate, add the first mixture and dissolve at 35°C to obtain the second mixture. S3. Add ethylenediaminetetraacetic acid and polyethylene glycol to the second mixture, mix well, and obtain the defluorinating agent.

[0025] Example 3 A wastewater defluoridating agent comprises the following components by weight: 50 parts polyaluminum ferric chloride, 8 parts sodium carboxymethyl cellulose, 12 parts ferric ammonium ethylenediaminetetraacetic acid, 6 parts sodium lauryl phosphate, 10 parts ethylenediaminetetraacetic acid, 2 parts polyethylene glycol, and 220 parts water. Its preparation method includes the following steps: S1. Dissolve polyaluminum ferric chloride in water, add sodium carboxymethyl cellulose to obtain the first mixture; S2. After mixing ferric ammonium ethylenediaminetetraacetate and sodium lauryl phosphate, add the first mixture and dissolve at 45°C to obtain the second mixture. S3. Add ethylenediaminetetraacetic acid and polyethylene glycol to the second mixture, mix well, and obtain the defluorinating agent.

[0026] Example 4 The only difference between this embodiment and Embodiment 3 is that the raw materials in this embodiment include the following components by weight: 50 parts of polyaluminum ferric chloride, 8 parts of sodium carboxymethyl cellulose, 4 parts of ferric ammonium ethylenediaminetetraacetate, 14 parts of sodium lauryl phosphate, 10 parts of ethylenediaminetetraacetic acid, 2 parts of polyethylene glycol, and 220 parts of water.

[0027] Example 5 The only difference between this embodiment and embodiment 3 is that the raw materials in this embodiment include the following components by weight: 50 parts of polyaluminum ferric chloride, 8 parts of sodium carboxymethyl cellulose, 6 parts of ferric ammonium ethylenediaminetetraacetate, 12 parts of sodium lauryl phosphate, 10 parts of ethylenediaminetetraacetic acid, 2 parts of polyethylene glycol, and 220 parts of water.

[0028] Example 6 The only difference between this embodiment and Embodiment 3 is that the raw materials in this embodiment include the following components by weight: 50 parts of polyaluminum ferric chloride, 8 parts of sodium carboxymethyl cellulose, 9 parts of ferric ammonium ethylenediaminetetraacetate, 9 parts of sodium lauryl phosphate, 10 parts of ethylenediaminetetraacetic acid, 2 parts of polyethylene glycol, and 220 parts of water.

[0029] Example 7 The difference between this embodiment and Embodiment 3 is that the raw materials in this embodiment include the following components by weight: 50 parts of polyaluminum ferric chloride, 8 parts of sodium carboxymethyl cellulose, 10.8 parts of ferric ammonium ethylenediaminetetraacetate, 7.2 parts of sodium lauryl phosphate, 10 parts of ethylenediaminetetraacetic acid, 2 parts of polyethylene glycol, and 220 parts of water.

[0030] Example 8 The only difference between this embodiment and Example 6 is that the raw materials in this embodiment include the following components by weight: 50 parts of polyaluminum ferric chloride, 8 parts of sodium carboxymethyl cellulose, 9 parts of ferric ammonium ethylenediaminetetraacetate, 9 parts of sodium lauryl phosphate, 4 parts of ethylenediaminetetraacetic acid, 8 parts of polyethylene glycol, and 220 parts of water.

[0031] Example 9 The only difference between this embodiment and Embodiment 6 is that the raw materials in this embodiment include the following components by weight: 50 parts of polyaluminum ferric chloride, 8 parts of sodium carboxymethyl cellulose, 9 parts of ferric ammonium ethylenediaminetetraacetate, 9 parts of sodium lauryl phosphate, 6 parts of ethylenediaminetetraacetic acid, 6 parts of polyethylene glycol, and 220 parts of water.

[0032] Example 10 The only difference between this embodiment and Embodiment 6 is that the raw materials in this embodiment include the following components by weight: 50 parts of polyaluminum ferric chloride, 8 parts of sodium carboxymethyl cellulose, 9 parts of ferric ammonium ethylenediaminetetraacetate, 9 parts of sodium lauryl phosphate, 8 parts of ethylenediaminetetraacetic acid, 4 parts of polyethylene glycol, and 220 parts of water.

[0033] Example 11 The only difference between this embodiment and Embodiment 6 is that the raw materials in this embodiment include the following components by weight: 50 parts of polyaluminum ferric chloride, 8 parts of sodium carboxymethyl cellulose, 9 parts of ferric ammonium ethylenediaminetetraacetate, 9 parts of sodium lauryl phosphate, 9 parts of ethylenediaminetetraacetic acid, 3 parts of polyethylene glycol, and 220 parts of water.

[0034] Comparative Example 1 The only difference between this comparative example and Example 2 is that the raw materials in this comparative example include the following components by weight: 40 parts of polyaluminum ferric chloride, 5 parts of sodium carboxymethyl cellulose, 25 parts of ferric ammonium ethylenediaminetetraacetic acid, 15 parts of ethylenediaminetetraacetic acid, 1 part of polyethylene glycol, and 200 parts of water.

[0035] Comparative Example 2 The only difference between this comparative example and Example 2 is that the raw materials in this comparative example include the following components by weight: 40 parts of polyaluminum ferric chloride, 5 parts of sodium carboxymethyl cellulose, 25 parts of sodium lauryl phosphate, 15 parts of ethylenediaminetetraacetic acid, 1 part of polyethylene glycol, and 200 parts of water.

[0036] Comparative Example 3 The only difference between this comparative example and Example 2 is that the raw materials in this comparative example include the following components by weight: 40 parts of polyaluminum ferric chloride, 5 parts of sodium carboxymethyl cellulose, 15 parts of ethylenediaminetetraacetic acid, 1 part of polyethylene glycol, and 200 parts of water.

[0037] Comparative Example 4 The only difference between this comparative example and Example 2 is that the raw materials in this comparative example include the following components by weight: 40 parts of polyaluminum ferric chloride, 5 parts of sodium carboxymethyl cellulose, 20 parts of ferric ammonium ethylenediaminetetraacetate, 5 parts of sodium lauryl phosphate, 16 parts of ethylenediaminetetraacetic acid, and 200 parts of water.

[0038] Comparative Example 5 The only difference between this comparative example and Example 2 is that the raw materials in this comparative example include the following components by weight: 40 parts of polyaluminum ferric chloride, 5 parts of sodium carboxymethyl cellulose, 20 parts of ferric ammonium ethylenediaminetetraacetate, 5 parts of sodium lauryl phosphate, 16 parts of polyethylene glycol, and 200 parts of water.

[0039] Comparative Example 6 The only difference between this comparative example and Example 2 is that the raw materials in this comparative example include the following components by weight: 40 parts of polyaluminum ferric chloride, 5 parts of sodium carboxymethyl cellulose, 20 parts of ferric ammonium ethylenediaminetetraacetate, 5 parts of sodium lauryl phosphate, and 200 parts of water.

[0040] The wastewater defluoridating agents prepared in Examples 1-11 and Comparative Examples 1-6 were tested according to the following method: Take a batch of wastewater with a fluoride content of 20.0 mg / L, take 10 L of each as a sample, add 15 mL of the defluorinating agent prepared in Examples 1-11 and Comparative Examples 1-6 respectively, stir at 50 rpm for 12 h at room temperature, detect the fluoride content, and calculate the defluorination rate. The specific test data are shown in Table 1.

[0041] The defluorination rate is calculated as follows: A = (20.0 - c1) / c1 × 100%; c1 is the fluorine concentration measured after 12 hours.

[0042]

[0043] Comparing Example 2 with Comparative Examples 1-3, it is shown that the synergistic effect of ferric ammonium ethylenediaminetetraacetate and sodium lauryl phosphate in the present invention improves the defluorination rate of the wastewater defluorinator. Comparing Example 2 with Comparative Examples 4-6, it is shown that the synergistic effect of ethylenediaminetetraacetic acid and polyethylene glycol in the present invention improves the defluorination rate of the wastewater defluorinator.

[0044] Comparing Examples 5-7 with Examples 3-4, it is shown that adjusting the mass ratio of ferric ammonium ethylenediaminetetraacetate (EDTA) to sodium lauryl phosphate to 0.5-1.5:1 further improves the defluorination rate of the wastewater defluorinator. Comparing Example 6 with Examples 5 and 7, it is shown that adjusting the mass ratio of ferric ammonium EDTA to sodium lauryl phosphate to 1:1 in this invention achieves the best defluorination rate improvement for the wastewater defluorinator. Comparing Examples 9-11 with Examples 6 and 8, it is shown that adjusting the mass ratio of EDTA to polyethylene glycol to 1-3:1 in this invention further improves the defluorination rate of the wastewater defluorinator. Comparing Example 10 with Examples 9 and 11, it is shown that adjusting the mass ratio of EDTA to polyethylene glycol to 2:1 in this invention achieves the best defluorination rate improvement for the wastewater defluorinator.

[0045] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wastewater defluoridating agent, characterized in that, The raw materials include the following components by weight: 40-60 parts of polyaluminum ferric chloride, 5-10 parts of sodium carboxymethyl cellulose, 2-20 parts of ferric ammonium ethylenediaminetetraacetate, 5-20 parts of sodium lauryl phosphate, 5-15 parts of ethylenediaminetetraacetic acid, 1-10 parts of polyethylene glycol, and 200-240 parts of water. The mass ratio of ferric ammonium ethylenediaminetetraacetate to sodium lauryl phosphate is 0.5~1.5:1; The mass ratio of ethylenediaminetetraacetic acid to polyethylene glycol is 1~3:

1.

2. The wastewater defluoridator according to claim 1, characterized in that, The mass ratio of ferric ammonium ethylenediaminetetraacetate to sodium lauryl phosphate is 1:

1.

3. The wastewater defluoridator according to claim 1, characterized in that, The mass ratio of ethylenediaminetetraacetic acid to polyethylene glycol is 2:

1.

4. The wastewater defluoridator according to claim 1, characterized in that, The basicity of the polyaluminum ferric chloride is 60%~90%.

5. The wastewater defluoridator according to claim 1, characterized in that, The polyethylene glycol includes one of PEG-800, PEG-1000, and PEG-1500.

6. The wastewater defluoridator according to claim 5, characterized in that, The polyethylene glycol is PEG-1000.

7. A method for preparing a wastewater defluoridator according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Dissolve polyaluminum ferric chloride in water, add sodium carboxymethyl cellulose to obtain the first mixture; S2. After mixing ferric ammonium ethylenediaminetetraacetate and sodium lauryl phosphate, add the first mixture and dissolve to obtain the second mixture; S3. Add ethylenediaminetetraacetic acid and polyethylene glycol to the second mixture, mix well, and obtain a defluorinating agent.

8. The method for preparing a wastewater defluoridating agent according to claim 7, characterized in that, The dissolution temperature described in S2 is 35~55℃.

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