Preparation method of manganese-based hydrotalcite and application of manganese-based hydrotalcite in removing vanadium pollution

Abstract

The invention relates to a preparation method of manganese-based hydrotalcite and application of the manganese-based hydrotalcite in removing vanadium pollution. According to the invention, the manganese-based hydrotalcite is prepared by adopting a nucleation crystallization method by accurately regulating and controlling the hydrotalcite laminate element composition, the interlayer ion species and the atomic proportion. The prepared manganese-based hydrotalcite realizes high-selectivity specific rapid adsorption of vanadium pollutants through surface hydroxyl complexing, interlayer anion exchange, electrostatic interaction and the like. Even in a complex adsorption environment, such as interference of different pH values, various common metal cations and organic matters, the manganese-based hydrotalcite can still keep the adsorption efficiency higher than 95%.

Description

Technical Field

[0001] This invention belongs to the field of environmental pollution remediation technology, and particularly relates to a method for preparing manganese-based hydrotalcite and its application in removing vanadium pollution. Background Technology

[0002] With the rapid development of industries such as metallurgy, chemical engineering, and energy, the emissions of vanadium and its compounds have increased year by year, leading to increasingly prominent vanadium pollution problems in water bodies and soil. Pentavalent vanadium (V(V)), as the main environmental form of vanadium, has high solubility, mobility, and biotoxicity, and easily accumulates in organisms through the food chain, posing a serious threat to ecosystems and human health. Existing studies have shown that long-term exposure to vanadium-containing environments can lead to respiratory damage, nervous system disorders, and carcinogenic risks. Many domestic and international environmental standards have set strict limits on the emission concentration of vanadium (such as my country's "Integrated Wastewater Discharge Standard," which stipulates a maximum allowable emission concentration of vanadium of 1.0 mg / L).

[0003] Currently, the main technologies for treating vanadium-containing wastewater include chemical precipitation, ion exchange, membrane separation, and electrochemical methods. However, these methods have significant limitations: chemical precipitation requires large amounts of reagents, producing vanadium-containing sludge that is difficult to dispose of and easily causes secondary pollution; while ion exchange has good treatment effects, the resin is expensive, difficult to regenerate, and has limited adsorption capacity for low concentrations of vanadium; membrane separation technology requires high operating pressure and energy consumption, and the membrane modules are prone to fouling and scaling, making large-scale application difficult; electrochemical methods involve large equipment investment, complex operation and maintenance, and their treatment efficiency is significantly affected by fluctuations in water quality. Therefore, developing efficient, economical, and environmentally friendly vanadium pollution control technologies has become an urgent problem to be solved in the industry.

[0004] Adsorption methods have shown broad application prospects in the treatment of heavy metal wastewater due to their advantages such as simple operation, low energy consumption, regenerable adsorbents, and no secondary pollution. Especially for water bodies with low concentrations of vanadium pollution, adsorption can achieve selective enrichment and efficient removal through the design of functional materials. However, traditional adsorbents (such as activated carbon and natural minerals) suffer from problems such as low adsorption capacity, poor selectivity, and excessively long time to reach adsorption equilibrium, which limit their practical application.

[0005] In recent years, research on layered double hydroxide materials and their modified adsorbents has gradually become a hot topic. Layered double hydroxides (LDHs), also known as hydrotalcite, are unique intercalation materials with advantages such as tunable layered metal cations and interlayer anions, controllable grain size and thickness, topological transformation capability, and extremely low solubility.

[0006] Studies have found that modifying the composition of LDHs can mineralize some heavy metal ions into the LDHs layers through isomorphous substitution, significantly reducing the free nature of heavy metals and thus achieving ultra-stable mineralization of heavy metals. This enables long-term stable removal of heavy metal ions and remediation of heavy metal environmental pollution.

[0007] In addition, LDHs can also fix heavy metal pollutants in the interlayer or on the surface through complexation of surface hydroxyl groups, interlayer anion exchange, electrostatic interaction, etc., so as to achieve the purpose of removing heavy metal pollution. However, there are no reports on the research and development of LDHs for vanadium pollution and the study of their adsorption effects. Summary of the Invention

[0008] The purpose of this invention is to design an LDHs product for vanadium pollution to achieve long-term and stable removal of heavy metal ions and to remediate heavy metal environmental pollution.

[0009] In view of the technical problems existing in the prior art, this invention designs a method for preparing manganese-based hydrotalcite and its application in the removal of vanadium pollution. This invention achieves rapid and efficient adsorption of vanadium by controlling the elemental composition of the hydrotalcite layers, the types of interlayer ions, and the proportional relationship of each atom, thereby ensuring that wastewater discharge meets my country's surface water discharge standards. Simultaneously, its adsorption effect is almost unaffected by interference factors such as metal cations, organic matter, and pH changes in the water body, achieving effective removal of vanadium pollutants from natural water bodies.

[0010] It should be noted that, in this invention, unless otherwise specified, the specific meaning of "comprising" in relation to composition definition and description includes both open-ended meanings such as "comprising," "including," etc., and closed-ended meanings such as "composed of," etc., and similar meanings.

[0011] To solve the aforementioned technical problems, the present invention adopts the following solution:

[0012] [The first technical solution]

[0013] A method for preparing manganese-based hydrotalcite includes the following steps:

[0014] Step 1: Place M 2+ and M 3+ Chlorides or soluble salts according to M 2+ / M 3+ Mix the solids in a molar ratio of 1-3, then add enough deionized water (usually 3-10 times the total mass) to dissolve the solids, to obtain solution A.

[0015] Step 2: Based on M 2+ With M 3+Take 1-2 times the sum of the molar amounts of sodium hydroxide or potassium hydroxide, and add enough deionized water to dissolve the solid, usually 3-10 times the total mass of the solid, to obtain solution B;

[0016] Step 3: Mix solutions A and B using a colloid mill to form nuclei, then perform a crystallization reaction. After the reaction is complete, remove the slurry, wash it, separate it by centrifugation to obtain the solid product, and dry it to obtain manganese-based hydrotalcite.

[0017] Among them, M 2+ and M 3+ These represent divalent and trivalent metal cations on the plate, respectively;

[0018] The divalent metal cation is Mn. 2+ and Mg 2+ Ni 2+ Zn 2+ Ca 2+ One of them;

[0019] The trivalent metal cation is Al. 3+ Cr 3+ Fe 3+ and Ga 3+ One of them.

[0020] Furthermore, the nucleation reaction described in step 3 takes 1 to 5 minutes.

[0021] Furthermore, the conditions for the crystallization reaction described in step 3 are: a temperature range of 40-80℃, a stirring speed of 300-800 rpm, and a crystallization reaction time of 0.5-2 hours.

[0022] Furthermore, the washing described in step 3 involves washing the slurry with deionized water.

[0023] Furthermore, the drying described in step 3 is carried out at 50-70°C for 8-20 hours.

[0024] In this invention, there are no special requirements for obtaining solid products by centrifugation, as long as a high purity solid product can be obtained.

[0025] The reason why the magnesium manganese aluminum intercalated layered double hydroxides (MgMnAl-Cl-LDHs) prepared in this invention have better adsorption performance is as follows:

[0026] The hydrotalcite described in this invention exhibits excellent adsorption performance for vanadium pollution in water, which is achieved through a synergistic mechanism of anion intercalation and surface complexation. Specifically, the layered structure of hydrotalcite allows vanadate ions to enter the interlayer channels through anion exchange, achieving interlayer intercalation; simultaneously, the metal sites on the layers coordinate with vanadate ions in the inner layer, forming stable surface complexes. Combined with the electrostatic interaction on the layer surface, this achieves efficient fixation and stable adsorption of vanadium.

[0027] In the aforementioned adsorption mechanism, the introduction of manganese is key to improving adsorption performance. Mn(II), as a structural site with strong Lewis acidity, exhibits a significantly higher coordination affinity for vanadate ions than other metal ions, serving as the main active center for enhancing adsorption capacity and selectivity. Simultaneously, the introduction of manganese optimizes the electronic structure and surface microenvironment of the layers, not only enhancing the structural stability of the material but also effectively lowering the reaction energy barrier for forming inner-layer complexes with vanadate ions. Furthermore, Mn(II) reacts with trivalent ions (Al2O3) in the layers... 3+ Cr 3+ Fe 3+ and Ga 3+ One of them, through synergistic coordination, together with the divalent ions (Mg) on ​​another layer, constructs a highly reactive adsorption interface, which, together with the divalent ions (Mg) on ​​the other layer, forms a highly reactive adsorption interface. 2+ Ni 2+ Zn 2+ Ca 2+ The combined effects of one of the components optimize the electronic structure and surface microenvironment of the layer, resulting in a significant improvement in the vanadium contamination adsorption performance of the hydrotalcite described in this invention compared to other LDH materials.

[0028] [Second Technical Solution]

[0029] The present invention also discloses a manganese-based hydrotalcite, which is prepared according to the above-described method for preparing manganese-based hydrotalcite.

[0030] The manganese-based hydrotalcite has the general chemical formula [M 2+ 1-x M 3+ x (OH)2][A n- x / n •mH2O],

[0031] Among them, M 2+ and M 3+ These represent divalent and trivalent metal cations on the plate, respectively;

[0032] A n- Interlayer anions;

[0033] n is the charge number of the anion;

[0034] x is M 3+ With M 2+ +M 3+ The molar ratio has a range of 0.25 ≤ x ≤ 0.5;

[0035] m represents the number of water molecules in the interlayer, and its value ranges from 0 to m to 4.

[0036] Furthermore, the divalent metal cation is Mn. 2+ and Mg 2+ Ni 2+ Zn 2+ Ca 2+ One of them;

[0037] The trivalent metal cation is Al. 3+ Cr 3+ Fe 3+ and Ga 3+ One of them.

[0038] Furthermore, the A mentioned above n- It is one or more of chloride ions, nitrate ions, carbonate ions, dodecyl sulfate ions, benzoate ions, and borate ions.

[0039] [The third technical solution]

[0040] The present invention also discloses the use of the above-mentioned manganese-based hydrotalcite in the removal of vanadium pollution from wastewater.

[0041] This invention is applicable to the treatment of high-concentration vanadium-containing wastewater discharged from vanadium smelting, vanadium battery processing, steel and chemical industries.

[0042] Its high adsorption capacity and effectiveness over a wide pH range enable it to withstand complex water quality conditions and achieve compliant discharge of vanadium concentration in the effluent.

[0043] To address the pollution of surrounding surface water and groundwater caused by leachate from vanadium-titanium magnetite mining areas and tailings ponds, this invention serves as a high-performance reactive medium for constructing permeable reactive barriers (PRBs), effectively immobilizing and blocking the diffusion of vanadium pollution plumes. Its stable chemical immobilization effectively reduces vanadium migration and bioavailability, ensuring the safety of drinking water sources.

[0044] This invention, with its rapid adsorption kinetics (equilibrium reached within 20 minutes), is ideally suited for emergency response to sudden vanadium pollution incidents, such as transport leaks or production accidents. It can be developed into a mobile treatment device or used as an adsorbent package for rapid dosing, achieving efficient and rapid purification of contaminated water.

[0045] This invention provides a method for preparing manganese-based hydrotalcite and its application in vanadium pollution removal, which has the following beneficial effects:

[0046] 1. The manganese-based hydrotalcite prepared by this invention can rapidly and significantly reduce the concentration of vanadate ions in solution, with a removal efficiency of up to 99% or more and an average removal rate of over 95%. Even under conditions of common anion and cation concentrations and pH interference, this manganese-based hydrotalcite can still maintain excellent adsorption performance and meet the requirements for removing vanadium pollution from natural water bodies to meet discharge standards.

[0047] 2. The manganese-based hydrotalcite prepared by this invention is prepared by nucleation method, which is simple and environmentally friendly, and meets the national requirements for environmentally friendly and green chemical products.

[0048] 3. The manganese-based layered double hydroxide (LDH) of this invention achieves rapid, highly selective, and specific adsorption of vanadium contaminants through surface hydroxyl complexation, interlayer anion exchange, electrostatic interactions, and redox reactions. Even in complex adsorption environments, such as different pH values, various common metal cations, and interference from organic matter, this manganese-based LDH maintains high adsorption efficiency. Attached Figure Description

[0049] Figure 1 : This is a graph showing the effect of MgMnAl-Cl-LDHs, MgAl-Cl-LDHs and MgCaAl-Cl-LDHs hydrotalcite prepared in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention on the adsorption of vanadate ions over time.

[0050] Figure 2 : This is a graph showing the effect of MgMnAl-Cl-LDHs hydrotalcite prepared in Example 1 on the adsorption of vanadate ions under different environmental conditions. Detailed Implementation

[0051] The present invention will be further described below with reference to specific embodiments and accompanying drawings:

[0052] Example 1:

[0053] A total of 45 kg of MgCl2, MnCl2, and AlCl3 in a molar ratio of 1.5:0.5:1 were added to 150 kg of deionized water and thoroughly dissolved and mixed to form a slurry. Separately, 15 kg of NaOH was dissolved in 150 kg of deionized water. Both slurries were then added to a colloid mill for nucleation treatment for 1 minute. After that, the mixture was transferred to a stirred tank for crystallization.

[0054] Within a temperature range of 60℃, the stirring speed was set to 500 rpm, and the slurry was removed after the reaction lasted for 2 hours.

[0055] Subsequently, the slurry was washed several times with deionized water to separate and obtain solid products. The obtained products were dried at 60°C for 10 hours to finally obtain magnesium manganese aluminum intercalated hydrotalcite MgMnAl-Cl-LDHs.

[0056] Example 2

[0057] A total of 40 kg of MgCl2, MnCl2, and AlCl3 in a molar ratio of 0.5:0.5:1 were added to 150 kg of deionized water and thoroughly dissolved and mixed to form a slurry. Separately, 15 kg of NaOH was dissolved in 150 kg of deionized water. Both slurries were then added to a colloid mill for nucleation treatment for 5 minutes. After that, the mixture was transferred to a stirred tank for crystallization.

[0058] Within a temperature range of 80℃, the stirring speed was set to 800 rpm, and the slurry was removed after the reaction lasted for 0.5 hours.

[0059] Subsequently, the slurry was washed several times with deionized water to separate and obtain the solid product. The obtained product was dried at 50°C for 20 hours to finally obtain magnesium manganese aluminum intercalated hydrotalcite MgMnAl-Cl-LDHs.

[0060] Example 3

[0061] A total of 40 kg of MgCl2, MnCl2, and AlCl3 in a molar ratio of 2:1:1 were added to 400 kg of deionized water and thoroughly dissolved and mixed to form a slurry. Separately, 15 kg of NaOH was dissolved in 150 kg of deionized water. Both slurries were then added to a colloid mill for nucleation treatment for 3 minutes. After that, the mixture was transferred to a stirred tank for crystallization.

[0062] Within a temperature range of 40℃, the stirring speed was set to 300 rpm, and the slurry was removed after the reaction lasted for 1.5 hours.

[0063] Subsequently, the slurry was washed several times with deionized water to separate and obtain solid products. The obtained products were dried at 70°C for 8 hours to finally obtain magnesium manganese aluminum intercalated hydrotalcite MgMnAl-Cl-LDHs.

[0064] Example 4

[0065] A total of 40 kg of CaCl2, MnCl2, and AlCl3 in a molar ratio of 1.5:0.5:1 were added to 150 kg of deionized water and thoroughly dissolved and mixed to form a slurry. Separately, 15 kg of NaOH was dissolved in 150 kg of deionized water. Both slurries were then added to a colloid mill for nucleation treatment for 1 minute. After that, the mixture was transferred to a stirred tank for crystallization.

[0066] Within a temperature range of 40℃, the stirring speed was set to 400 rpm, and the reaction system was protected with N2. The slurry was removed after the reaction lasted for 1.5 hours.

[0067] Subsequently, the slurry was washed several times with deionized water to separate and obtain solid products. The obtained products were dried at 50°C for 8 hours to finally obtain calcium manganese aluminum intercalated hydrotalcite CaMnAl-Cl-LDHs.

[0068] Example 5

[0069] A total of 40 kg of MgCl2, MnCl2, and FeCl3 in a molar ratio of 1.5:0.5:1 were added to 150 kg of deionized water and thoroughly dissolved and mixed to form a slurry. Separately, 15 kg of NaOH was dissolved in 150 kg of deionized water. Both slurries were then added to a colloid mill for nucleation treatment for 5 minutes. After that, the mixture was transferred to a stirred tank for crystallization.

[0070] Within a temperature range of 60℃, the stirring speed was set to 600 rpm, and the slurry was removed after the reaction lasted for 1.5 hours.

[0071] Subsequently, the slurry was washed several times with deionized water to separate and obtain solid products. The obtained products were dried at 60°C for 8 hours to finally obtain magnesium manganese iron intercalated hydrotalcite MgMnFe-Cl-LDHs.

[0072] The crystal structure of the product of this invention embodiment was characterized using an XRD-6000 X-ray powder diffractometer manufactured by Shimadzu Corporation of Japan. Comparison with the standard image library JCPDS#22-0700 shows that:

[0073] The characteristic diffraction peaks (003), (006), (009), (110), and (015) of the MgMnAl-Cl-LDHs synthesized in Examples 1-3 have 2θ positions consistent with the standard spectrum, but the peak heights are lower. This is related to the addition of manganese to the layer, which reduces the crystallinity. However, it still proves that it has a layered structure, and MgMnAl-Cl-LDHs were successfully synthesized.

[0074] The adsorption efficiency is evaluated by placing the material in a vanadate ion solution of a specific concentration and measuring the change in the concentration of vanadate ions in the solution before and after adsorption.

[0075] The vanadate ion solution was prepared by dissolving vanadium salt in ultrapure water, with a concentration range of 10-500 mg / L. Adsorption experiments were conducted at a constant temperature of 25°C for 2 hours, using a magnetic stirrer maintained at a stirring speed of 500 rpm.

[0076] After the experiment, the solution was filtered using a 0.22 μm membrane filter to separate solid particles. The residual concentration of vanadate ions in the filtered solution was accurately determined using ICP-OES technology.

[0077] Experimental results are as follows Figure 1 As shown, the MgMnAl-Cl-LDHs material can achieve an adsorption efficiency of over 99% in a vanadate ion solution with a concentration of 50 mg / L, and the adsorption rate is extremely fast. After adding the adsorbent, the vanadate ion removal rate reaches 97.7% in 10 minutes and 99.0% in 20 minutes.

[0078] The adsorption efficiency evaluation method for the MgMnAl-Cl-LDHs materials in Examples 2 and 3 is the same as above, and the average adsorption efficiency in a vanadate ion solution with a concentration of 50 mg / L is higher than 95%.

[0079] The adsorption efficiency evaluation method of the LDHs materials in Examples 4 and 5 is the same as above. The average adsorption efficiency in a vanadate ion solution with a concentration of 50 mg / L is 70-80%. It can be used in scenarios where vanadium pollution is not very serious, and can also achieve the effect of purifying water and restoring the environment.

[0080] The investigation of environmental disturbance factors includes temperature, pH value, different types of cations, and organic matter content.

[0081] In the temperature effect experiment, 50 mg of MgMnAl-Cl-LDHs was added to 100 mL of vanadate ion solution (50 mg / L), and the temperature range was set to 298-318 K.

[0082] In the experiment on the effect of pH on removal performance, 50 mg of MgMnAl-Cl-LDHs was added to 100 mL of vanadate ion solution (50 mg / L), and the initial pH range was adjusted from 2 to 12.

[0083] In the cation selectivity experiment, a fixed dose of 0.5 g / L MgMnAl-Cl-LDHs was used in a vanadate ion solution at a concentration of 50 mg / L. Different cations (Na... + Mg 2+ K + Ca 2+ The ionic strength was adjusted to 100, 200 and 500 mg / L.

[0084] In the organic matter selectivity experiment, a fixed dose of 0.5 g / L MgMnAl-Cl-LDHs was used in the vanadate ion solution at a concentration of 50 mg / L. The concentrations of organic matter, including humic acid (HA) and EDTA, were set at 100, 200, and 500 mg / L. The initial pH was maintained at 7.0 throughout the experiment.

[0085] Experimental results are as follows Figure 2 As shown in (a), at the same initial concentration, temperature has little effect on adsorption efficiency, while increasing temperature slightly promotes adsorption. As the initial concentration of vanadate ions increases, the adsorption efficiency decreases. When the concentration of vanadate ions is 500 mg / L, the adsorption efficiency can still be maintained at around 85%.

[0086] like Figure 2 As shown in (b), pH has a slight effect on the adsorption effect, especially under strongly alkaline conditions (pH=12), the adsorption efficiency is significantly reduced. This is related to the properties of vanadate ions. Under strongly alkaline conditions, a certain amount of vanadate ions are converted into other ionic forms and are not easily adsorbed, resulting in a decrease in adsorption efficiency. In the pH range of 2-10, the adsorption efficiency fluctuates slightly, but remains above 97%.

[0087] like Figure 2 As shown in (c), for interference from cations, low to medium concentrations of Na + Mg 2+ K + Ca 2+ The adsorption effect is not significantly affected; the adsorption efficiency remains around 99% at all concentrations, except for high concentrations of Na. + (500 mg / L) has a significant impact on the adsorption effect, but such a high concentration of Na... + Its content is extremely rare in common environmental scenarios.

[0088] like Figure 2 As shown in (d), EDTA has little effect on the adsorption effect, and the adsorption efficiency can reach more than 90% at all concentrations. High concentrations of HA (500 mg / L) have a slight effect on the adsorption effect, but such high concentrations of HA are rarely seen in common environmental scenarios.

[0089] In summary, the influence of various environmental factors on the adsorption effect is within an acceptable range. Therefore, the present invention can still maintain a high adsorption capacity to meet the needs of practical applications even in general complex environments.

[0090] Comparative Example 1:

[0091] Steps: Add 35 kg of MgCl2 and AlCl3 in a molar ratio of 2:1 to 150 kg of deionized water, dissolve and mix thoroughly to make a slurry. Separately, dissolve 15 kg of NaOH in 150 kg of deionized water. Add both slurries to a colloid mill for nucleation treatment for 1 minute. Then transfer the mixture to a stirred tank for crystallization.

[0092] At 60℃, the stirring speed was set to 500 rpm, and the reaction was carried out for 6 hours before the slurry was taken out. Subsequently, the slurry was washed several times with deionized water to separate and obtain the solid product. The obtained product was dried at 60℃ for 10 hours, and finally magnesium aluminum intercalated hydrotalcite MgAl-Cl-LDHs was obtained.

[0093] The crystal structure of the product was characterized using an XRD-6000 X-ray powder diffractometer from Shimadzu Corporation of Japan. Comparison with the standard image library JCPDS#22-0700 revealed the following:

[0094] The characteristic diffraction peaks (003), (006), and (110) of the synthesized MgAl-Cl-LDHs in Comparative Example 1 are consistent with the 2θ positions of the standard spectrum, proving that MgAl-Cl-LDHs were successfully synthesized and have the typical structure of LDHs, indicating that the sample has a complete crystal structure and high crystallinity.

[0095] The adsorption efficiency was evaluated by placing magnesium aluminum intercalated hydrotalcite in a solution of vanadate ions of a specific concentration and measuring the change in the concentration of vanadate ions in the solution before and after adsorption.

[0096] The vanadate ion solution was prepared by dissolving vanadium salt in ultrapure water, with a concentration range of 10-500 mg / L. Adsorption experiments were conducted at a constant temperature of 25°C for 2 hours, using a magnetic stirrer maintained at a stirring speed of 500 rpm.

[0097] After the experiment, the solution was filtered using a 0.22 μm membrane filter to separate solid particles. The residual concentration of vanadate ions in the filtered solution was accurately determined using ICP-OES technology.

[0098] Experimental results are as follows Figure 1 As shown, the MgAl-Cl-LDHs material has an adsorption efficiency of only 42.2% in a vanadate ion solution with a concentration of 50 mg / L, and the adsorption rate is also slow. After adding the adsorbent for 60 minutes, the vanadate ion removal rate only reached 40.1%.

[0099] This comparative example 1 clearly demonstrates that, with all other components remaining the same, the ternary manganese-based hydrotalcite synthesized with the addition of manganese ions exhibits a significantly better adsorption effect on vanadate ions than the binary hydrotalcite without the addition of manganese.

[0100] Comparative Example 2:

[0101] Steps: Add 40 kg of MgCl2, CaCl2 and AlCl3 in a molar ratio of 1.5:0.5:1 to 150 kg of deionized water, dissolve and mix thoroughly to make a slurry. Separately, dissolve 15 kg of NaOH in 150 kg of deionized water. Add both slurries to a colloid mill for nucleation treatment for 1 minute. Then transfer to a stirred tank for crystallization reaction.

[0102] At 60℃, the stirring speed was set to 500 rpm, and the reaction system was protected with nitrogen. After the reaction lasted for 6 hours, the slurry was taken out. Subsequently, the slurry was washed several times with deionized water to separate and obtain the solid product. The obtained product was dried at 60℃ for 10 hours, and finally magnesium calcium aluminum intercalated hydrotalcite MgCaAl-Cl-LDHs was obtained.

[0103] The crystal structure of the product was characterized using an XRD-6000 X-ray powder diffractometer from Shimadzu Corporation of Japan. Comparison with the standard image library JCPDS#22-0700 revealed the following:

[0104] The characteristic diffraction peaks (003), (006), and (110) of the synthesized MgCaAl-Cl-LDHs in Comparative Example 2 are consistent with the 2θ positions of the standard spectrum, proving that MgCaAl-Cl-LDHs were successfully synthesized and have the typical structure of LDHs, indicating that the sample has a complete crystal structure and high crystallinity.

[0105] The adsorption efficiency was evaluated by placing magnesium-calcium-aluminum intercalated hydrotalcite in a solution of vanadate ions of a specific concentration and measuring the change in the concentration of vanadate ions in the solution before and after adsorption.

[0106] Vanadate ion solutions were prepared by dissolving vanadium salts in ultrapure water, with concentrations ranging from 10 to 500 mg / L. Adsorption experiments were conducted at a constant temperature of 25°C for 2 hours, using a magnetic stirrer maintained at a stirring speed of 500 rpm.

[0107] After the experiment, the solution was filtered using a 0.22 μm membrane filter to separate solid particles. The residual concentration of vanadate ions in the filtered solution was accurately determined using ICP-OES technology.

[0108] Experimental results are as follows Figure 1As shown, the MgCaAl-Cl-LDHs material has a maximum adsorption efficiency of only 64.5% in a vanadate ion solution with a concentration of 50 mg / L, and the adsorption rate is also slow. It takes 30 minutes after adding the adsorbent for the vanadate ion removal rate to reach 60.7%.

[0109] This comparative example clearly demonstrates that, with all other components remaining the same, the ternary manganese-based hydrotalcite synthesized by adding manganese ions exhibits significantly better adsorption performance for vanadate ions than the non-manganese-based ternary hydrotalcite.

[0110] The manganese-based hydrotalcite prepared by this invention can rapidly and significantly reduce the concentration of vanadate ions in solution, with extremely high removal efficiency. Even under conditions of common anion and cation concentrations and pH interference, the manganese-based hydrotalcite of this invention can still maintain excellent adsorption performance and meet the requirements for removing vanadium pollution from natural water bodies to meet discharge standards.

[0111] The present invention has been described above by way of example with reference to the embodiments and accompanying drawings. Obviously, the implementation of the present invention is not limited to the above-described manner. Any improvements made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A method for the preparation of a manganese-based hydrotalcite, characterized in that, The method comprises the following steps: Step 1: M 2+ and chloride or soluble salt of M 3+ are mixed in a ratio of 1-3 of M 2+ / M 3+ mole ratio, then deionized water is added to dissolve the solid, usually 3-10 times the total mass, to obtain solution A; Step 2: According to M 2+ With M 3+ An amount of 1-2 times the sum of the moles of sodium hydroxide or potassium hydroxide is taken, and deionized water is added to dissolve the solid, usually 3-10 times the total mass of the solid, to obtain solution B; Step 3: mixing solution A and solution B through a colloid mill for nucleation treatment, and then performing a crystallization reaction; after the reaction is completed, the slurry is taken out, washed, and the solid product is obtained through centrifugal separation and dried to obtain the manganese-based hydrotalcite; wherein M 2+ and M 3+ represent divalent and trivalent metal cations, respectively, on the layer. the divalent metal cation is Mn 2+ and Mg 2+ , Ni 2+ , Zn 2+ , Ca 2+ one of the trivalent metal cation is one of Al 3+ , Cr 3+ , Fe 3+ , and Ga 3+ .

2. The method for preparing the manganese-based hydrotalcite according to claim 1, characterized in that: The time of the nucleation reaction in step 3 is 1-5 minutes.

3. The method for preparing the manganese-based hydrotalcite according to claim 1, characterized in that: The crystallization reaction in step 3 is performed under the following conditions: the temperature is 40-80℃, the stirring speed is 300-800 rpm, and the crystallization reaction time is 0.5-2 hours.

4. The method for preparing the manganese-based hydrotalcite according to claim 3, characterized in that: The washing in step 3 is performed by using deionized water to wash the slurry.

5. The method for preparing the manganese-based hydrotalcite according to claim 4, characterized in that: The drying in step 3 is performed at 50-70℃ for 8-20 hours.

6. A manganese-based hydrotalcite characterized in that: The manganese-based hydrotalcite is prepared by the method for preparing the manganese-based hydrotalcite according to any one of claims 1-5.

7. The manganese-based hydrotalcite according to claim 6, characterized in that: with the general chemical formula [M 2+ 1-x M 3+ x (OH)2][A n- x / n •mH2O], wherein, M 2+ and M 3+ represent divalent and trivalent metal cations on the layer, respectively; A n- is an interlayer anion; n is the charge number of the anion; x is M 3+ with M 2+ + M 3+ in a molar ratio ranging from 0.25≤x≤0.5; m represents the number of interlayer water molecules, and the value range is 0≤m≤4.

8. The manganese-based hydrotalcite according to claim 7, characterized in that: the divalent metal cation is Mn 2+ and Mg 2+ , Ni 2+ , Zn 2+ , Ca 2+ one of the trivalent metal cation is one of Al 3+ , Cr 3+ , Fe 3+ , and Ga 3+ .

9. The manganese-based hydrotalcite according to claim 7, characterized in that: The A n- is one or more of chloride, nitrate, carbonate, dodecyl sulfate, benzoate, borate.

10. The use of the manganese-based hydrotalcite according to claim 6 in removing vanadium pollution in sewage.

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