Flower-shaped lanthanum-magnesium oxide defluorination agent, preparation method and application thereof

Abstract

The application discloses a flower-shaped lanthanum-magnesium oxide fluoride removing agent and a preparation method and application thereof. The preparation method comprises the following steps: dissolving lanthanum salt, magnesium salt, urea and PVP in a solvent to obtain a reaction solution; placing the reaction solution in a temperature of 140-200 DEG C to react; separating the reaction material to obtain a solid product after the reaction; and washing, drying and calcining the solid product in sequence to obtain the flower-shaped lanthanum-magnesium oxide fluoride removing agent. The fluoride removing agent is composed of La2CO5 and MgO, the flower-shaped structure can effectively prevent the problems of surface area reduction and active site reduction caused by self-agglomeration, the surface is rich in a large number of hydroxyl active groups, carbonate active groups, magnesium ion and lanthanum ion active sites, the fluoride removing agent can utilize physical action and chemical action to quickly remove fluoride ions in water, effectively remove low-concentration fluoride ions in water, and overcome the defects of low fluoride ion adsorption capacity and slow speed of conventional materials.

Description

Technical Field

[0001] This invention belongs to the field of water purification materials and water treatment technology, specifically relating to a flower-shaped lanthanum magnesium oxide defluorinating agent, its preparation method, and its application. Background Technology

[0002] Fluorine is a naturally occurring trace chemical element, essential for the growth of bones and teeth in plants and animals. However, excessive intake of fluoride ions can lead to a range of diseases, such as dental fluorosis, skeletal fluorosis, and damage to the kidneys, liver, and brain, causing immune dysfunction and, in severe cases, even death. my country's "Standards for Drinking Water Quality" (GB5749-2022) clearly stipulates that the fluoride content in drinking water should be less than 1.0 mg / L. Fluoride pollution is caused by both geological factors, such as regionally high-fluoride groundwater, and by excessive fluoride emissions from modern industrial production. Improper disposal of fluoride-containing wastewater, waste gas, and waste residue generated during these production processes can cause serious fluoride pollution.

[0003] The areas in my country with excessive fluoride ion levels in water sources are mainly concentrated in the Northwest region, as well as some economically underdeveloped areas. Due to the dispersed geographical locations, complex environments, diverse forms of fluoride contamination, unclear removal mechanisms, high treatment difficulty, and high costs, the overall foundation of fluoride pollution treatment technology remains weak, resulting in the fact that the problem of fluoride pollution in my country's drinking water has not yet been effectively resolved. Therefore, the development of efficient fluoride pollution treatment materials and technologies is of great social, economic, and environmental significance and is urgently needed.

[0004] The treatment and improvement of fluoride ion concentration in water has been a hot topic in recent years. Traditional technologies for removing fluoride ions from drinking water include coagulation and sedimentation, adsorption, membrane separation, ion exchange, and electrochemical methods. Compared with other technologies, adsorption is more mature, less expensive, and simpler to operate, making it widely used as a highly efficient method for removing ions from water. However, low concentrations of fluoride ions in water are difficult to remove because the lower the fluoride ion concentration, the lower the adsorption capacity of the material. Materials need sufficient active sites to effectively capture these low concentrations of fluoride ions, and most materials struggle to reduce fluoride ion concentrations to below 1 ppm. Therefore, developing adsorbents capable of adsorbing low concentrations of fluoride ions is urgently needed. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a flower-like lanthanum magnesium oxide defluorinating agent, its preparation method, and its application. The preparation method provided by this invention can rapidly prepare the flower-like lanthanum magnesium oxide defluorinating agent, which can quickly remove low concentrations of fluoride ions from water.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a flower-shaped lanthanum magnesium oxide defluorinating agent includes the following steps:

[0008] Lanthanum salt, magnesium salt, urea, and PVP are dissolved in a solvent to obtain a reaction solution. The reaction solution is placed in a sealed reaction vessel and reacted at 140–200°C for 1–3 hours. After the reaction, the reactants are separated to obtain a solid product. The solid product is then washed, dried, and calcined to obtain a flower-shaped lanthanum magnesium oxide defluorinating agent. In the above reaction process, PVP acts as a structure directing agent, enabling the material to form a flower-like structure, which greatly reduces the material agglomeration.

[0009] As a preferred technical solution, the molar ratio of the lanthanum salt to the magnesium salt is (0.5-2):1. Further, the lanthanum salt is at least one selected from lanthanum nitrate, lanthanum chloride, and lanthanum acetate; and the magnesium salt is at least one selected from magnesium nitrate, magnesium chloride, and magnesium acetate.

[0010] As a preferred technical solution, the solvent is ethanol, an aqueous solution of ethanol, DMF, or an aqueous solution of DMF.

[0011] As a preferred technical solution, the washing involves alternating rinsing with water and ethanol several times; the drying temperature is 40-80℃, and the time is 12-24 hours; the calcination equipment is a muffle furnace, and the calcination temperature is 300-500℃, and the time is 2-5 hours.

[0012] Another object of the present invention is to provide a flower-like lanthanum magnesium oxide defluorinating agent prepared by the above-described preparation method, wherein the flower-like lanthanum magnesium oxide defluorinating agent is composed of La2CO5 and MgO; when the flower-like lanthanum magnesium oxide defluorinating agent functions in water, its surface is rich in hydroxyl active groups, carbonate active groups, magnesium ion and lanthanum ion active sites, and the carbonate ions it contains have a good F ion removal effect under alkaline conditions, which may be because the carbonate active sites avoid OH under alkaline conditions. - With F - Competition with [other technologies] enables the rapid removal of low concentrations of fluoride ions from water.

[0013] The third objective of this invention is to provide the application of the above-described flower-shaped lanthanum magnesium oxide defluorinating agent in removing fluoride ions from water. After adsorption, the flower-shaped lanthanum magnesium oxide defluorinating agent obtained by filtration can be reused by soaking in an alkaline solution.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] The flower-like lanthanum magnesium oxide defluorinating agent provided by this invention is composed of La2CO5 and MgO. Its flower-like structure effectively prevents the reduction of surface area and active sites caused by material aggregation. Its surface has a large number of active groups, enabling it to rapidly remove low concentrations of fluoride ions from water through physical and chemical actions. It achieves rapid adsorption and capture of fluoride ions, removing an initial concentration of approximately 5 mg / L of fluoride ions within 5 minutes, bringing the concentration down to below 1 mg / L (the standard for drinking water). This overcomes the shortcomings of conventional materials, such as low adsorption capacity and slow speed. The defluorinating agent prepared by this invention can be recycled and reused, without causing secondary pollution to water bodies. The preparation method provided by this invention is time-efficient and simple, improving production efficiency and making it suitable for industrial production. Attached Figure Description

[0016] Figure 1 The image shows the SEM morphology of the flower-shaped lanthanum magnesium oxide defluorinating agent material prepared in Example 3.

[0017] Figure 2 The images show the XRD patterns of the flower-shaped lanthanum magnesium oxide defluorinating agent materials prepared in Examples 1 to 3.

[0018] Figure 3 The graph shows the fluoride removal rate of the flower-shaped lanthanum magnesium oxide defluorinating agent material prepared in Example 3. Detailed Implementation

[0019] The present invention will be further described below with reference to embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0021] Example 1

[0022] A method for preparing a flower-shaped lanthanum magnesium oxide defluorinating agent includes the following steps:

[0023] Step 1: Add lanthanum salt and magnesium salt in a 1:1 molar ratio (1.732 g lanthanum nitrate hexahydrate, 1.026 g magnesium nitrate hexahydrate), 1.3 g urea and 2.4 g PVP to 60 ml DMF solution and stir at room temperature for 2 h;

[0024] Step 2: Pour the above solution into a 100ml polytetrafluoroethylene inner liner and react at 170℃ for 2 hours;

[0025] Step 3: Separate the reaction products from the solution by centrifugation, wash with ethanol and water 5 times in a cycle, dry in a vacuum environment at 60℃ for 12 hours, and calcine in a muffle furnace at 300℃ for 2 hours to obtain the flower-shaped lanthanum magnesium oxide defluorinating agent.

[0026] Experiments were conducted on actual fluoride-containing water samples. The testing method was as follows: the initial fluoride ion concentration in the fluoride-containing water sample was 5 mg / L, the dosage of the defluorinating agent was 0.3 g / L, and the temperature was 35℃ (the testing methods in other embodiments below are the same as in this embodiment). The test results showed that the flower-like lanthanum magnesium oxide defluorinating agent could reduce the fluoride concentration from an initial concentration of 5 mg / L to below 1.0 mg / L within 3 minutes, meeting the drinking water standard.

[0027] Example 2

[0028] A method for preparing a flower-shaped lanthanum magnesium oxide defluorinating agent includes the following steps:

[0029] Step 1: Add lanthanum salt and magnesium salt in a 1:2 molar ratio (1.155g lanthanum nitrate hexahydrate, 1.367g magnesium nitrate hexahydrate), 2g urea and 3.0g PVP to 60ml ethanol, stir at room temperature for 1h to obtain the reaction solution;

[0030] Step 2: Pour the above reaction solution into a high-pressure reactor with a 100ml polytetrafluoroethylene liner and react at 200℃ for 1 hour.

[0031] Step 3: Separate the reaction products by centrifugation, wash them 6 times with ethanol and water, dry them in a vacuum environment at 80℃ for 24 hours, and calcine them in a muffle furnace at 350℃ for 4 hours to obtain the flower-shaped lanthanum magnesium oxide defluorinating agent.

[0032] Test results on actual fluoride-containing water samples show that the flower-shaped lanthanum magnesium oxide defluorinating agent can reduce the fluoride concentration from an initial concentration of 5 mg / L to below 1.0 mg / L within 5 minutes, meeting drinking water standards.

[0033] Example 3

[0034] A method for preparing a flower-shaped lanthanum magnesium oxide defluorinating agent includes the following steps:

[0035] Step 1: Add lanthanum salt and magnesium salt in a 1:1 molar ratio (1.485 g lanthanum chloride heptahydrate, 0.813 g magnesium chloride hexahydrate), 2.8 g urea and 2.0 g PVP to 60 ml ethanol solution, stir at room temperature for 3 h to obtain the reaction solution;

[0036] Step 2: Pour the above reaction solution into a 100ml polytetrafluoroethylene inner liner and react at 180℃ for 1.5h;

[0037] Step 3: Separate the reaction products by centrifugation, wash them 5 times with ethanol and water, dry them in a vacuum environment at 40°C for 18 hours, and calcine them in a muffle furnace at 400°C for 3 hours to obtain the flower-shaped lanthanum magnesium oxide defluorinating agent.

[0038] Figure 1 The image shows the SEM morphology of the product obtained in Example 3. It can be seen that it consists of nanosheets stacked into a flower-like structure, which effectively prevents the easy accumulation of sheet-like structures, thus reducing its surface area and active sites. This material has a micro / nano structure and exists in water in colloidal form, and will not completely dissolve.

[0039] Figure 2 The images show the XRD patterns of the flower-shaped lanthanum magnesium oxide defluorinating agent materials prepared in Examples 1 to 3. The XRD patterns show that the flower-shaped lanthanum magnesium oxide defluorinating agent is composed of La2CO5 and MgO.

[0040] The test results on actual fluoride-containing water samples show that the material prepared in Example 3 can reduce the fluoride concentration from an initial concentration of 5 mg / L to below 1.0 mg / L within 5 minutes, meeting the drinking water standard.

[0041] Figure 3 The graph shows the recycling removal rate of the flower-shaped lanthanum magnesium oxide defluorinating agent material prepared in Example 3. Figure 3 It can be seen that after multiple cycles of use, the material still maintains a high removal rate of fluoride ions in water, demonstrating excellent recyclability.

[0042] Example 4

[0043] A method for preparing a flower-shaped lanthanum magnesium oxide defluorinating agent includes the following steps:

[0044] Step 1: Add lanthanum salt and magnesium salt in a 2:1 molar ratio (1.685 g lanthanum acetate hydrate, 0.572 g magnesium acetate tetrahydrate), 1.3 g urea and 2.4 g PVP to 60 ml DMF solution, stir at room temperature for 2 h to obtain the reaction solution;

[0045] Step 2: Pour the above solution into a 100ml polytetrafluoroethylene inner liner and react at 190℃ for 2 hours;

[0046] Step 3: Separate the reaction products by centrifugation, wash them three times with ethanol and water, dry them under vacuum at 60°C, and calcine them in a muffle furnace at 500°C for 3 hours to obtain the flower-shaped lanthanum magnesium oxide defluorinating agent.

[0047] Test results on actual fluoride-containing water samples show that the flower-shaped lanthanum magnesium oxide defluorinating agent can reduce the fluoride concentration from an initial concentration of 5 mg / L to below 1.0 mg / L, meeting drinking water standards.

[0048] Comparative Example 1

[0049] Compared with Example 3, the solution in step one is replaced with pure water, while all other processes are the same as in Example 1.

[0050] Experimental results on actual fluoride-containing water samples showed that the prepared material could reduce the fluoride concentration from an initial concentration of 5 mg / L to 4.582 mg / L within 15 minutes, failing to meet the water standard of less than 1.0 mg / L. This indicates that the product prepared using organic solvents such as ethanol or DMF has superior performance. This is mainly because organic solvents cause structural changes in the material during the reaction, increasing the surface area and reducing material aggregation, thus creating more adsorption active sites and enabling the capture of fluoride ions in water. In contrast, when water is used as a solvent, the surface area of ​​the material formed in the aqueous solution is relatively small, resulting in poorer performance.

[0051] Comparative Example 2

[0052] Compared with Example 3, the urea in step one is replaced with 5ml of ammonia water and CO2 gas is flushed for 10 minutes, while the other processes are the same as in Example 1.

[0053] Test results on actual fluoride-containing water samples show that the prepared material can reduce the fluoride concentration from an initial concentration of 5 mg / L to 3.258 mg / L within 10 minutes, which does not meet the water standard of less than 1.0 mg / L.

[0054] Comparative Example 3

[0055] Compared with Example 3, no magnesium salt is added in step one, the amount of lanthanum salt used is the sum of lanthanum salt and magnesium salt in Example 1, and all other processes are the same as in Example 1.

[0056] Test results on actual fluoride-containing water samples showed that the prepared product could reduce the fluoride concentration from an initial concentration of 5 mg / L to 2.582 mg / L within 10 minutes, which did not meet the water standard of less than 1.0 mg / L.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a flower-like lanthanum magnesium oxide defluorinating agent, characterized in that: Includes the following steps: Lanthanum salt, magnesium salt, urea, and PVP are dissolved in a solvent to obtain a reaction solution. The reaction solution is placed in a sealed reaction vessel and reacted at a temperature of 140~200ºC. After the reaction is completed, the reaction materials are separated to obtain a solid product. The solid product is then washed, dried, and calcined to obtain a flower-shaped lanthanum magnesium oxide defluorinating agent. The solvent is ethanol, an aqueous solution of ethanol, DMF, or an aqueous solution of DMF; The calcination temperature is 300~500℃; The flower-shaped lanthanum magnesium oxide defluorinating agent is composed of La2CO5 and MgO; the flower-shaped lanthanum magnesium oxide defluorinating agent is rich in hydroxyl active groups, carbonate active groups, magnesium ion and lanthanum ion active sites.

2. The method for preparing the flower-like lanthanum magnesium oxide defluorinating agent according to claim 1, characterized in that: The molar ratio of the lanthanum salt to the magnesium salt is (0.5-2):

1.

3. The method for preparing the flower-like lanthanum magnesium oxide defluorinating agent according to claim 2, characterized in that: The lanthanum salt is at least one of lanthanum nitrate, lanthanum chloride, and lanthanum acetate.

4. The method for preparing the flower-like lanthanum magnesium oxide defluorinating agent according to claim 2, characterized in that: The magnesium salt is at least one of magnesium nitrate, magnesium chloride, and magnesium acetate.

5. The method for preparing the flower-like lanthanum magnesium oxide defluorinating agent according to claim 1, characterized in that: The reaction time at the temperature of 140~200ºC is 1~3 hours.

6. The method for preparing the flower-like lanthanum magnesium oxide defluorinating agent according to claim 1, characterized in that: The drying temperature is 40~80℃, and the time is 12~24h.

7. The method for preparing the flower-like lanthanum magnesium oxide defluorinating agent according to claim 1, characterized in that: The calcination time is 2-5 hours.

8. A flower-shaped lanthanum magnesium oxide defluorinating agent, characterized in that: It is prepared by the preparation method as described in any one of claims 1 to 7.

9. The application of the flower-shaped lanthanum magnesium oxide defluorinating agent as described in claim 8 in the removal of fluoride ions from water.

Images