A La-Mg LDH@Ti3C2T x Defluorinating agents, their preparation methods and applications

Abstract

This invention discloses a La-Mg LDH@Ti3C2T x Defluorinating agent, its preparation method, and its application. The preparation method of this material includes the following steps: placing Ti3AlC2 in an alkaline solution and reacting to obtain Ti3C2T. x ; Lanthanum salt, magnesium salt and Ti3C2T x Dispersed in water, and with the addition of an alkaline substance to adjust the solution to alkalinity, La-Mg LDH@Ti3C2T was obtained through a reaction. x Precursor; La-Mg LDH@Ti3C2T x The precursor was calcined at high temperature to obtain the target product. The La-Mg LDH@Ti3C2T synthesized in this invention... x Medium- to nano-sheet-like La-Mg LDH enters Ti3C2T x The gaps can effectively increase the distance between them, and La-Mg LDH exists in Ti3C2T x The gaps between the particles effectively limit the tendency of LDH to aggregate. The material has a large specific surface area and active adsorption sites, which is beneficial for the rapid adsorption of fluoride ions in water.

Description

Technical Field

[0001] This invention belongs to the field of water purification materials and water treatment technology, specifically relating to a La-Mg LDH@Ti3C2T x Defluorinating agents, their preparation methods, and applications. 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] Due to the dispersed geographical locations, complex environments, diverse forms of fluoride pollution, unclear removal mechanisms, high treatment difficulty, and high costs, the overall technological foundation for fluoride pollution treatment remains relatively weak. 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 removal 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 to 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, current adsorption methods suffer from low adsorption capacity and low adsorption efficiency when using adsorption materials to remove fluoride ions from water. Summary of the Invention

[0005] To address the shortcomings and deficiencies of existing technologies, the purpose of this invention is to provide a La-Mg LDH@Ti3C2T x The defluorinating agent, its preparation method, and its application: This material has a surface rich in hydroxyl active groups, magnesium ion, lanthanum ion, and titanium ion active sites, enabling it to rapidly remove fluoride ions through ion exchange.

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

[0007] The first objective of this invention is to provide a La-Mg LDH@Ti3C2T x The preparation method of the defluorinating agent includes the following steps:

[0008] (1) Ti3AlC2 was placed in an alkaline solution and reacted at 200–300 °C for 24–72 h. The reaction product was separated and dried to obtain Ti3C2T. x Preferably, the alkaline solution is a sodium hydroxide solution with a concentration of 20–30 mol / L. Alkaline treatment can yield Ti3C2T rich in a large number of hydroxyl radicals. x The higher the hydroxyl content, the stronger the material's ability to adsorb fluoride ions.

[0009] (2) Lanthanum salt, magnesium salt and Ti3C2T x The solution was dispersed in water, and an alkaline substance was added to adjust the solution to alkalinity to obtain a reaction solution. The reaction solution was placed at a temperature of 60-80℃ for reaction. The reaction product was washed and dried to obtain La-Mg LDH@Ti3C2T. x Precursor; preferably, the molar ratio of the lanthanum salt to the magnesium salt is 1:(1-3); the alkaline substance is a mixed solution of sodium hydroxide and sodium carbonate;

[0010] (3) La-Mg LDH@Ti3C2 T x La-Mg LDH@Ti3C2T was obtained by high-temperature calcination of the precursor. x The defluorinating agent is subjected to high-temperature calcination in an inert atmosphere at a temperature of 350-450°C for 3-5 hours.

[0011] Another object of the present invention is to provide La-Mg LDH@Ti3C2T prepared by the above-described preparation method. x Defluorinating agent, namely La-Mg LDH@Ti3C2T x Surface area is 300-400 m² 2 / g. The surface of this material is rich in hydroxyl active groups, magnesium ion, lanthanum ion and titanium ion active sites, which can effectively remove fluoride ions from water.

[0012] A third objective of this invention is to provide the La-Mg LDH@Ti3C2T described above. x The application of defluoridating agents in removing fluoride ions from water; after adsorption, the La-Mg LDH@Ti3C2T is obtained through filtration separation. x The compound can be reused by soaking in an alkaline solution.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] (1) La-Mg LDH@Ti3C2T synthesized using the method of the present invention x Defluorinating agent, nano-sheet La-Mg LDH enters Ti3C2Tx In the gaps, it can effectively increase the distance between the gaps, while La-Mg LDH exists in Ti3C2T x The gaps effectively limit the tendency of LDH to accumulate. After loading, its surface area is 300-400 m². 2 / g, with a large surface area, is conducive to the rapid adsorption of fluoride ions.

[0015] (2) La-Mg LDH@Ti3C2T synthesized using the method of the present invention x The defluoridating agent has a micro-nano structure. This adsorbent exists in water in colloidal form and does not completely dissolve. After adding a conventional flocculant, the colloidal state immediately transforms into a flocculent state, eventually settling down to achieve rapid separation of water and sludge without causing secondary pollution to the water body.

[0016] (3) La-Mg LDH@Ti3C2T synthesized using the method of the present invention x The fluoride removal agent has a surface rich in hydroxyl active groups, and the active sites of magnesium ion, lanthanum ion and titanium ion are fully exposed, which can achieve rapid adsorption and capture of fluoride ions and achieve adsorption effect.

[0017] (4) The La-Mg LDH@Ti3C2T synthesized in this invention x The defluoridating agent has a significantly increased number of surface-active groups, enabling it to adsorb and remove fluoride ions with an initial concentration of about 10 mg / L in water within less than 8 minutes, bringing the concentration down to below 1 mg / L, meeting the drinking water standard. This overcomes the shortcomings of conventional materials in terms of low fluoride ion adsorption capacity.

[0018] (5) The La-Mg LDH@Ti3C2T synthesized in this invention x After use, the defluorinating agent can be recycled through filtration, alkaline soaking, and drying, overcoming the shortcomings of conventional materials in regenerating fluoride ions.

[0019] (6) The synthesis method and process used in this invention are simple and easy to operate, and are suitable for large-scale industrial production. Attached Figure Description

[0020] Figure 1 Ti3C2T prepared in Example 1 x SEM image of the defluorinating agent;

[0021] Figure 2 The image shows the SEM morphology of the La-Mg LDH obtained in Example 1.

[0022] Figure 3 The La-Mg LDH@Ti3C2T prepared in Example 1 x SEM morphology image;

[0023] Figure 4 The La-Mg LDH@Ti3C2T prepared in Example 3 x The BET chart. Detailed Implementation

[0024] The present invention will be further described below with reference to embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.

[0025] In addition, unless otherwise specified, the preparation processes in the following embodiments are all conventional methods in the prior art, and therefore will not be described in detail; the raw materials used in the following embodiments are all commercially available.

[0026] Example 1

[0027] A La-Mg LDH@Ti3C2T x The preparation method of the defluorinating agent includes the following steps:

[0028] (1) Place 1g of Ti3AlC2 in 60ml of 27.5mol / L alkaline solution and react at 270℃ for 72 hours. After cooling, centrifuge to separate the solid product, wash several times with phosphoric acid, ethanol and deionized water in turn, and dry to obtain Ti3C2T x ;

[0029] (2) Add 1.299g of lanthanum nitrate hexahydrate, 0.256g of magnesium nitrate hexahydrate, and 1g of Ti3C2T x Solution A is formed by dissolving 2g of sodium carbonate and 2.8g of sodium hydroxide in 20ml of water; solution B is formed by adding 2g of sodium carbonate and 2.8g of sodium hydroxide to 20ml of water. Solution B is slowly added to solution A in a 65℃ water bath with continuous stirring for 24 hours. The solid product is separated by centrifugation, washed several times alternately with ethanol and deionized water, and dried to obtain La-MgLDH@Ti3C2T. x Precursor;

[0030] (3) La-Mg LDH@Ti3C2T x The precursor was calcined in a tube furnace under argon as the protective gas at 400℃ for 4 hours to obtain La-Mg LDH@Ti3C2T. x Defluorinating agent.

[0031] Figure 1 , Figure 2 , Figure 3 The Ti3C2T prepared in Example 1 are respectively x , La-Mg LDH and La-Mg LDH@Ti3C2T x SEM image of the material. From Figure 1 As can be seen from this, Ti3C2Tx Like an open book, the gaps in its structure make it possible to embed tiny nanomaterials into the crevices. From Figure 2 As can be seen, La-Mg LDH has a nanosheet structure with a very small thickness, allowing it to be completely embedded. Figure 1 From the gap. Figure 3 As can be seen, La-Mg LDH is well embedded in Ti3C2T x The gap stabilized the Ti3C2T x The structure of Ti3C2T x This effectively limited the aggregation of La-Mg LDH.

[0032] Experimental results from actual fluoride-containing water samples show that La-Mg LDH@Ti3C2T x It can reduce the fluoride concentration from an initial concentration of 10.00 mg / L to below 1.0 mg / L within 5 minutes, meeting drinking water standards.

[0033] Example 2

[0034] A La-Mg LDH@Ti3C2T x The preparation method of the defluorinating agent includes the following steps:

[0035] (1) Place 1g of Ti3AlC2 in 60ml of 27.5mol / L alkaline solution and react at 270℃ for 72 hours. After cooling, centrifuge to separate the solid product, wash several times with phosphoric acid, ethanol and deionized water in turn, and dry to obtain Ti3C2T x ;

[0036] (2) Add 1.299g of lanthanum nitrate hexahydrate, 0.256g of magnesium nitrate hexahydrate, and 2g of Ti3C2T x Solution A is formed by dissolving 2g of sodium carbonate and 2.8g of sodium hydroxide in 20ml of water; solution B is formed by adding 2g of sodium carbonate and 2.8g of sodium hydroxide to 20ml of water. Solution B is slowly added to solution A in a 60℃ water bath with continuous stirring for 24 hours. The solid product is separated by centrifugation, washed several times alternately with ethanol and deionized water, and dried to obtain La-MgLDH@Ti3C2T. x Precursor;

[0037] (3) La-Mg LDH@Ti3C2T x The precursor was calcined in a tube furnace under nitrogen as the protective gas at 360°C for 3 hours to obtain La-Mg LDH@Ti3C2T. x Defluorinating agent.

[0038] Experimental results from actual fluoride-containing water samples show that La-Mg LDH@Ti3C2T xIt can reduce the fluoride concentration from an initial concentration of 10.00 mg / L to below 1.0 mg / L within 8 minutes, meeting drinking water standards.

[0039] Example 3

[0040] A La-Mg LDH@Ti3C2T x The preparation method of the defluorinating agent includes the following steps:

[0041] (1) Place 1g of Ti3AlC2 in 60ml of 27.5mol / L alkaline solution and react at 270℃ for 24 hours. After cooling, centrifuge to separate the solid product, wash several times with phosphoric acid, ethanol and deionized water in turn, and dry to obtain Ti3C2T x ;

[0042] (2) Add 1.732g of lanthanum nitrate hexahydrate, 0.513g of magnesium nitrate hexahydrate, and 2g of Ti3C2T x Solution A is formed by dissolving 2g of sodium carbonate and 2.8g of sodium hydroxide in 20ml of water; solution B is formed by adding 2g of sodium carbonate and 2.8g of sodium hydroxide to 20ml of water. Solution B is slowly added to solution A in a 70℃ water bath with continuous stirring for 36 hours. After washing, centrifugation, and drying, La-Mg LDH@Ti3C2T is obtained. x Precursor;

[0043] (3) La-Mg LDH@Ti3C2T x The precursor was calcined in a tube furnace under argon as the protective gas at 420°C for 5 hours to obtain La-Mg LDH@Ti3C2T. x Defluorinating agent.

[0044] Figure 4 The La-Mg LDH@Ti3C2T prepared in Example 3 x The BET chart, from Figure 4 It can be seen that La-Mg LDH@Ti3C2T x Its specific surface area is 368.58 m². 2 / g, with a large specific surface area.

[0045] Experimental results from actual fluoride-containing water samples show that La-Mg-LDH@Ti3C2T x It can reduce the fluoride concentration from an initial concentration of 10.00 mg / L to below 1.0 mg / L within 5 minutes, meeting drinking water standards.

[0046] Example 4

[0047] A La-Mg LDH@Ti3C2T x The preparation method of the defluorinating agent includes the following steps:

[0048] (1) Place 1g of Ti3AlC2 in 60ml of 27.5mol / L alkaline solution and react at 270℃ for 48 hours. After cooling, centrifuge to separate the solid product, wash several times with phosphoric acid, ethanol and deionized water in turn, and dry to obtain Ti3C2T x ;

[0049] (2) Add 1.299g of lanthanum nitrate hexahydrate, 0.769g of magnesium nitrate hexahydrate, and 1g of Ti3C2T x Solution A is formed by dissolving 2g of sodium carbonate and 2.8g of sodium hydroxide in 20ml of water; solution B is formed by adding 2g of sodium carbonate and 2.8g of sodium hydroxide to 20ml of water. Solution B is slowly added to solution A in an 80℃ water bath with continuous stirring for 36 hours. The solid product is separated by centrifugation, washed several times alternately with ethanol and deionized water, and dried to obtain La-MgLDH@Ti3C2T. x Precursor;

[0050] (3) La-Mg LDH@Ti3C2T x The precursor was calcined in a tube furnace under argon as the protective gas at 450°C for 5 hours to obtain La-Mg LDH@Ti3C2T. x Defluorinating agent.

[0051] Experimental results from actual fluoride-containing water samples show that La-Mg-LDH@Ti3C2T x It can reduce the fluoride concentration from an initial concentration of 10.00 mg / L to below 1.0 mg / L within 6 minutes, meeting drinking water standards.

[0052] Comparative Example 1

[0053] Compared to Example 1, steps two and three are omitted, while all other processes are the same as in Example 1, resulting in a product of Ti3C2T. x .

[0054] The experimental results of actual fluoride-containing water samples show that Ti3C2T x It can reduce the fluoride concentration from an initial concentration of 10.00 mg / L to 7.358 mg / L within 15 minutes, but it cannot meet the water standard of less than 1.0 mg / L.

[0055] Comparative Example 2

[0056] Compared with Example 1, no lanthanum nitrate hexahydrate is added in step two, and the amount of magnesium nitrate hexahydrate used is the sum of lanthanum nitrate hexahydrate and magnesium nitrate hexahydrate used in Example 1. All other processes are the same as in Example 1.

[0057] Experimental results from actual fluoride-containing water samples show that Mg(OH)₂@Ti₃C₂T xIt can reduce the fluoride concentration from an initial concentration of 10.00 mg / L to 4.258 mg / L within 10 minutes, but it cannot meet the water standard of less than 1.0 mg / L.

[0058] Comparative Example 3

[0059] Compared with Example 1, no magnesium nitrate hexahydrate is added in step two, and the amount of lanthanum nitrate hexahydrate used is the sum of lanthanum nitrate hexahydrate and magnesium nitrate hexahydrate used in Example 1. All other processes are the same as in Example 1.

[0060] Experimental results from actual fluoride-containing water samples show that La(OH)3@Ti3C2T x It can reduce the fluoride concentration from an initial concentration of 10.00 mg / L to 2.584 mg / L within 10 minutes, but it cannot meet the water standard of less than 1.0 mg / L.

[0061] It should be noted that in other embodiments, the objective of this invention can be achieved when the experimental process meets the following conditions:

[0062] The reaction temperature in step (1) is preferably 200 to 300°C, specifically 200°C, 250°C, 300°C, etc.

[0063] The preferred calcination temperature in step (3) is 350-450℃, specifically 350℃, 400℃, 450℃, etc.; the preferred calcination time is 3-5h, specifically 3h, 4h, 5h, etc.

[0064] Those skilled in the art can make appropriate selections of the above process parameters according to actual needs, and all of them can achieve the purpose of this invention.

[0065] 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.

Claims

1. A La-Mg LDH@Ti3C2T x The method for preparing the defluorinating agent is characterized by: The following steps are involved: (1) Ti3AlC2 was placed in an alkaline solution and reacted at a temperature of 200–300 °C. The reaction product was separated and dried to obtain Ti3C2T. x ; (2) Lanthanum salt, magnesium salt and Ti3C2T x The solution was dispersed in water, and an alkaline substance was added to adjust the solution to alkalinity to obtain a reaction solution. The reaction solution was placed at a temperature of 60-80℃ for reaction. The reaction product was washed and dried to obtain La-Mg LDH@Ti3C2T. x Precursor; the molar ratio of the lanthanum salt to the magnesium salt is 1:(1-3); (3) La-Mg LDH@Ti3C2T x La-Mg LDH@Ti3C2T was obtained after calcination of the precursor. x Defluorinating agent; the calcination is carried out in an inert atmosphere.

2. The La-Mg LDH@Ti3C2T according to claim 1 x The method for preparing the defluorinating agent is characterized by: In step (1), the alkaline solution is a sodium hydroxide solution with a concentration of 20-30 mol / L.

3. The La-Mg LDH@Ti3C2T according to claim 1 x The method for preparing the defluorinating agent is characterized by: In step (1), the reaction time at a temperature of 200-300°C is 24-72 hours.

4. The La-Mg LDH@Ti3C2T according to claim 1 x The method for preparing the defluorinating agent is characterized by: In step (2), the alkaline substance is a mixed solution of sodium hydroxide and sodium carbonate.

5. The La-Mg LDH@Ti3C2T according to claim 1 x The method for preparing the defluorinating agent is characterized by: In step (2), the reaction time is 12 to 36 hours.

6. The La-Mg LDH@Ti3C2T according to claim 1 x The method for preparing the defluorinating agent is characterized by: In step (3), the calcination temperature is 350-450℃ and the duration is 3-5h.

7. La-Mg LDH@Ti3C2T prepared by the preparation method according to any one of claims 1-6 x Defluorinating agent.

8. The La-Mg LDH@Ti3C2T as described in claim 7 x Application of defluoridating agents in removing fluoride ions from water.

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