Morphology-controllable MOF (Metal Organic Framework) adsorption carrier, preparation method and fluorine removal application
By using a controllable morphology preparation method combining three-dimensional network and micron rod-shaped MOF crystals, the problems of adsorption capacity and separation and recovery of traditional carriers in the removal of fluoride ions from water were solved, achieving efficient and low-cost fluoride ion treatment.
Patent Information
- Application Number
- CN202511593589.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-03
- Publication Date
- 2026-01-02
AI Technical Summary
When existing adsorbent carriers remove fluoride ions in water, it is difficult to simultaneously achieve high adsorption capacity and easy separation and recovery. Traditional synthesis methods cannot effectively control the microstructure, resulting in low mass transfer efficiency and unstable flotation recovery rate.
MOF crystals with a composite three-dimensional network structure and a micron rod structure are used as adsorption carriers. They are prepared by solvothermal method and combined with sieving technology to form MOF adsorption carriers with controllable morphology, which are suitable for flotation separation process.
It achieves high adsorption capacity and stable solid-liquid separation, simplifies the preparation process, reduces operating costs, allows the adsorbent to be recycled, and ensures that the effluent fluoride ion concentration meets the standard.
Smart Images
Figure CN121244166A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of adsorption materials and water body treatment technology, and particularly relates to a controllable morphology MOF adsorption carrier, a preparation method and a defluorination application. BACKGROUND
[0002] The removal of excess fluoride ions in water bodies is a major demand in the field of environmental governance. Adsorption method is considered as one of the most promising technologies due to its high efficiency and simple operation. However, traditional adsorption separation processes, such as fixed bed filtration, have engineering bottlenecks such as bed clogging, limited treatment capacity, and poor adaptability to ultra-fine adsorbent powders. Especially for nanoscale adsorbents, the difficulty in solid-liquid separation and high recovery cost have become key obstacles to their large-scale application.
[0003] Carrier adsorption flotation technology, as an efficient foam extraction and separation method, adsorbs target pollutants onto adsorption carriers, and then realizes solid-liquid separation by means of bubble flotation, providing a new idea for solving the recovery problem of micro-fine adsorbents. In this technology system, the comprehensive performance of the adsorption carrier is the key to determining the process efficiency. An ideal carrier should have excellent characteristics in two dimensions: in the adsorption dimension, it should have high adsorption capacity, fast kinetics and excellent selectivity; in the flotation dimension, its surface hydrophobicity, particle morphology and size distribution must be efficient for bubble adhesion to ensure stable flotation recovery rate. Existing carriers (such as modified mineral powders and amorphous activated carbon) have inherent defects: their irregular and dense morphological structures not only limit the exposure of adsorption sites and mass transfer efficiency, but also make it difficult to control the surface hydrophobicity, resulting in low bubble-carrier collision adhesion efficiency and poor flotation selectivity and unstable recovery rate. Ultimately, the key problem is that the traditional synthesis method lacks precise directional control of the key parameter of micro-morphology.
[0004] Metal-organic framework (MOF) materials have ultra-high specific surface area and customizable pore structure, making them ideal high-performance adsorption carrier candidate materials. However, existing researches mostly focus on the adsorption performance exploration of conventional MOF powders, and their synthesis methods generally have inherent problems such as uncontrollable morphology and easy agglomeration of particles. More importantly, the inherent hydrophilic property and sub-micron particle size of MOF materials are fundamentally contradictory to their application requirements in the flotation system: on the one hand, irregular morphology covers active sites and increases mass transfer resistance; on the other hand, hydrophilic surface and small size make it impossible to effectively combine with bubbles, resulting in extremely low flotation recovery rate. Current research completely ignores the decisive role of carrier morphology in the conversion process from "adsorption performance" to "flotation adaptability".
[0005] The purpose of this invention is to resolve this contradiction by creating a novel MOF-based composite support through a controllable morphology preparation method. Its specific morphology is designed to simultaneously maximize fluoride adsorption efficiency (by increasing the accessibility of active sites and accelerating mass transfer) and adapt to the flotation separation process, thereby providing a completely new solution for efficient fluoride removal. Summary of the Invention
[0006] To address the problem that existing adsorption carriers cannot simultaneously achieve both high adsorption capacity and easy separation and recovery, the present invention aims to provide a controllable morphology MOF adsorption carrier with excellent adsorption and separation performance, its simple preparation method, and its efficient fluoride removal application.
[0007] The present invention achieves the above objectives through the following technical solutions:
[0008] A controllable morphology MOF adsorption carrier is provided, wherein the adsorption carrier is composed of a first morphology MOF crystal and a second morphology MOF crystal, wherein the first morphology is a three-dimensional network structure, the second morphology is a micron rod structure, and the MOF crystal is centered on a targeted adsorption metal.
[0009] A further improvement is that the mass ratio of the three-dimensional mesh structure MOF crystal to the micron rod-shaped MOF crystal is 1:5 to 5:1.
[0010] A further improvement is that the targeted adsorption metal is lanthanum.
[0011] The present invention also provides a method for preparing the controllable morphology MOF adsorbent support, the preparation method comprising the following steps: adding an adsorption functional targeting agent and an organic linker to a structure directing agent, performing a solvothermal reaction, then taking the reaction product and filtering, washing, drying and sieving to obtain two target morphology MOF adsorbent supports with three-dimensional network structure and micron rod structure respectively, and finally combining the two target morphology MOF adsorbent supports.
[0012] A further improvement is that the adsorption-targeting agent is at least one of lanthanum chloride, lanthanum carbonate, lanthanum nitrate, and lanthanum sulfate.
[0013] A further improvement is that the organic linker is at least one of terephthalic acid, 2-aminoterephthalic acid, and pyromellitic acid, and the structure directing agent is at least one of N,N-dimethylformamide, formic acid, and acetic acid.
[0014] Further improvements are made in the following aspects:
[0015] The solvothermal reaction refers to first dispersing the mixture by ultrasonication at 40~200 W power for 5~30 min to form a mixed solution, and then placing the mixed solution in a solvothermal reaction at 120~220℃ for 10~72 h;
[0016] The washing refers to washing with at least one washing solvent selected from N,N-dimethylformamide, methanol, ethanol or acetone;
[0017] The drying refers to vacuum drying at 60~130℃;
[0018] The sieving refers to sieving using standard molecular sieves, and the particle size distribution range of the two target morphologies of MOF adsorbents obtained by sieving is 30~120 μm and 150~400 μm.
[0019] The present invention also provides an application of the controllable morphology MOF adsorbent carrier for defluorination. The specific process of the defluorination application is as follows: the adsorbent carrier is added to fluoride-containing water at a dosage of 50~800 mg / L, and after adsorption for 5~210 min, a surfactant is added and flotation separation is performed. The separated adsorbent carrier is desorbed and regenerated and then recycled.
[0020] A further improvement is that the fluoride-containing water body is industrial fluoride-containing wastewater, high-fluoride groundwater, or high-fluoride geothermal water, and the fluoride ion concentration of the water body after treatment is less than 1.0 mg / L, the adsorption carrier is recycled at least 5 times, and the adsorption capacity is higher than 85%.
[0021] A further improvement is that the surfactant is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, α-olefin sulfonate, or sodium lauryl ether sulfate;
[0022] The flotation separation is carried out in a pressurized dissolved air flotation device;
[0023] The desorbent used in the desorption and regeneration process is at least one of hydrochloric acid, sodium hydroxide solution, sodium chloride solution, or sodium bicarbonate solution with a concentration of 0.01~1 mol / L.
[0024] The beneficial effects of this invention are as follows:
[0025] (1) Synergistic effect of adsorption and separation: By combining three-dimensional network structure (easy to separate) and micron rod-shaped (high-speed adsorption) MOF crystals, high adsorption capacity and efficient solid-liquid separation are achieved simultaneously.
[0026] (2) The preparation process is simple and controllable: the one-step solvothermal method combined with sieving separation is simple, the morphology is controllable, and it is easy to scale up.
[0027] (3) High efficiency and low cost: It integrates the whole process of "adsorption-flotation-regeneration", the effluent concentration is stable and meets the standards, and the adsorbent can be recycled, resulting in low operating costs. Attached Figure Description
[0028] Figure 1The image shows a scanning electron microscope (SEM) image of the controllable morphology MOF adsorbent prepared in Example 1 of the present invention. In the image, a shows a three-dimensional network MOF structure and b shows a micron rod-shaped MOF structure.
[0029] Figure 2 This is a process flow diagram of the preparation of the controllable morphology MOF adsorbent carrier described in this invention and its application in fluoride-containing water bodies. Detailed Implementation
[0030] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.
[0031]
Example 1
[0032] This embodiment provides the preparation of a controllable morphology MOF adsorbent La-MOF-1 and its application in the treatment of fluoride-containing water.
[0033] Preparation Example 1:
[0034] 3.5 mmol of lanthanum nitrate, used as the adsorption-targeting agent, and 2.0 mmol of 2-aminoterephthalic acid, used as the organic linker, were dissolved in 40 mL of N,N-dimethylformamide and ultrasonically dispersed at 100 W for 20 min. The mixed solution was transferred to a polytetrafluoroethylene-lined reactor and solvothermal reacted at 120 °C for 24 h. The product was filtered, washed with ethanol and methanol, and vacuum dried at 80 °C for 12 h. The dried powder was sieved through a standard molecular sieve to obtain a three-dimensional network MOF with a D50 of 35 μm and a micron rod-like MOF with a D50 of 180 μm. The two MOF crystals were mixed at a mass ratio of 1:2 to prepare the target adsorbent La-MOF-1.
[0035] Application Example 1:
[0036] 500 mL of industrial fluoride-containing wastewater with an initial fluoride ion concentration of 10.0 mg / L and pH=7.0 was taken, and 200 mg / L of La-MOF-1 was added. Adsorption was carried out at 25℃ and 150 rpm for 20 min with shaking. The results showed that the effluent fluoride ion concentration decreased to 0.52 mg / L. Subsequently, 70 mg / L of sodium dodecyl sulfate was added to the water sample, and the sample was transferred to a pressurized dissolved air flotation device for solid-liquid separation. The scum was collected, desorbed with 0.05 mol / L NaOH solution, washed with deionized water, and vacuum dried at 60℃. After five cycles of use, the adsorption capacity retention rate remained at 90.5%, and the effluent fluoride concentration remained consistently below 1.0 mg / L each time.
[0037]
Example 2
[0038] This example demonstrates the effect of different ratios on adsorption performance.
[0039] Preparation Example 2:
[0040] The preparation method is the same as in Example 1 of Example 1. A three-dimensional network structure MOF with a D50 of 35 μm obtained by sieving is mixed with a micron rod structure MOF with a D50 of 180 μm at a mass ratio of 2:3 to obtain the target adsorbent La-MOF-2.
[0041] Application Example 2:
[0042] The application method is the same as in Application Example 1 of Example 1. 500 mL of industrial fluoride-containing wastewater with an initial fluoride ion concentration of 10.0 mg / L and pH=7.0 was taken, and 200 mg / L of La-MOF-2 was added. Adsorption was performed at 25℃ and 150 rpm for 20 min with shaking. The results showed that the effluent fluoride ion concentration decreased to 0.95 mg / L. Subsequently, 50 mg / L of sodium dodecyl sulfate was added to the water sample, and the sample was transferred to a pressurized dissolved air flotation device for solid-liquid separation. The scum was collected, desorbed with 0.05 mol / L NaOH solution, washed with deionized water, and vacuum dried at 60℃. After five cycles of use, the adsorption capacity retention rate remained at 90.2%, and the effluent fluoride concentration was consistently below 1.0 mg / L each time.
[0043]
Example 3
[0044] This example demonstrates the performance of the adsorbent carrier under different metal sources, ligands, and reaction conditions.
[0045] Preparation Example 3:
[0046] Using 1.8 mmol lanthanum sulfate as the metal source and 2.0 mmol terephthalic acid as the ligand, the mixture was sonicated at 80 W for 30 min in 40 mL of a DMF:formic acid (volume ratio 9:1). The mixture was then transferred to a polytetrafluoroethylene-lined reactor and solvothermal reacted at 180 °C for 48 h. The product was filtered, washed with ethanol and acetone, and vacuum dried at 80 °C for 12 h. The dried powder was sieved using a standard molecular sieve to obtain a three-dimensional network MOF with a D50 of 90 μm and a micron rod-like MOF with a D50 of 300 μm. The two MOF morphologies were mixed at a mass ratio of 1:4 to prepare the target adsorbent La-MOF-3.
[0047] Application Example 3:
[0048] Fluoride-containing wastewater with an initial fluoride ion concentration of 30.0 mg / L and pH=8.0 was treated with 100 mg / L La-MOF-3. After adsorption for 30 min, the fluoride ion concentration in the effluent decreased to 0.48 mg / L. After flotation separation (with the addition of 80 mg / L sodium dodecyl sulfate) and regeneration, the capacity retention rate was 91.1% after 5 cycles.
[0049] Comparative Example 1
[0050] To investigate the necessity of targeted metal adsorption, this comparative example uses Al (prepared as in Example 1, but without sieving; all powder after reaction is used directly) as a trivalent metal for comparison testing. 3.5 mmol of aluminum chloride was weighed as the targeted adsorption agent, and 2.0 mmol of 2-aminoterephthalic acid was weighed as the organic linker, dissolved in 40 mL of N,N-dimethylformamide, and ultrasonically dispersed at 100 W for 20 min. The mixed solution was transferred to a polytetrafluoroethylene-lined reactor and solvothermal reacted at 120 °C for 24 h. The reaction product was filtered, washed with ethanol and methanol, and vacuum dried at 80 °C for 12 h. After drying, a three-dimensional flower-like MOF adsorbent carrier with uniform size and a D50 of 4.0 μm was obtained (denoted as Al-MOF).
[0051] 500 mL of industrial fluoride-containing wastewater with an initial fluoride ion concentration of 10.0 mg / L and pH=7.0 was taken, and 200 mg / L of Al-MOF was added. Adsorption was carried out at 25℃ and 150 rpm for 20 min with shaking. The results showed that the fluoride ion concentration in the effluent decreased to 6 mg / L. Subsequently, 200 mg / L of sodium dodecyl sulfate was added to the water sample, and the mixture was transferred to a pressurized dissolved air flotation device for solid-liquid separation. The scum was collected, desorbed with 0.05 mol / L NaOH solution, washed with deionized water, and vacuum dried at 60℃. After five cycles of use, the adsorption capacity retention rate of the adsorbent carrier was 35%.
[0052] Comparative Example 2
[0053] To investigate the limitations of single-morphology materials, 3.5 mmol of lanthanum nitrate was weighed as the adsorption targeting agent, and 2.0 mmol of 2-aminoterephthalic acid was weighed as the organic linker. The solutions were dissolved in 40 mL of N,N-dimethylformamide and ultrasonically dispersed at 100 W for 20 min. The mixed solution was transferred to a polytetrafluoroethylene-lined reactor and solvothermal reacted at 110 °C for 24 h. The reaction product was filtered, washed with ethanol and methanol, and vacuum dried at 80 °C for 12 h. A single, dense, blocky MOF with a D50 of 130 μm (denoted as NP-1) was obtained as the adsorption support.
[0054] 500 mL of industrial fluoride-containing wastewater with an initial fluoride ion concentration of 10.0 mg / L and pH=7.0 was taken, and 200 mg / L of NP-1 was added. Adsorption was performed at 25℃ and 150 rpm for 180 min with shaking. The results showed that the effluent fluoride ion concentration decreased to 2.26 mg / L. Subsequently, 150 mg / L of sodium dodecylbenzenesulfonate was added to the water sample, and the mixture was transferred to a pressurized dissolved air flotation device for solid-liquid separation. The scum was collected, desorbed with 0.15 mol / L sodium bicarbonate solution, washed with deionized water, and vacuum dried at 60℃. After two cycles, the adsorption capacity retention rate significantly decreased to below 60%.
[0055] Comparative Example 3
[0056] To illustrate the necessity of sieving, this comparative example uses the unsieved product CP-1 (prepared in the same way as in Example 1, but without sieving; all the powder after the reaction is used directly) for comparison testing. 500 mL of industrial fluoride-containing wastewater with an initial fluoride ion concentration of 10.0 mg / L and pH=7.0 was taken, and 200 mg / L of CP-1 was added. Adsorption was performed at 25℃ and 150 rpm for 20 min with shaking. The results showed that the fluoride ion concentration in the effluent decreased to 1.39 mg / L. Subsequently, 130 mg / L of sodium dodecyl sulfate was added to the water sample, and the sample was transferred to a pressurized dissolved air flotation device for solid-liquid separation. The scum was collected, desorbed with 0.05 mol / L NaOH solution, washed with water, and dried for regeneration. After five cycles, the adsorption capacity retention rate of this adsorbent carrier reached 68%.
[0057] Comparative Example 4
[0058] To illustrate the necessity of the specific morphological component compounding ratio, this comparative example uses a three-dimensional network MOF and a micron rod-shaped MOF at a mass ratio of 1:10 for comparison testing. The preparation method is the same as in Preparation Example 1 of Example 1. A three-dimensional network MOF with a D50 of 35 μm obtained by sieving was mixed with a micron rod-shaped MOF with a D50 of 180 μm at a mass ratio of 1:10 to prepare the target adsorbent CP-2. The application method is the same as in Application Example 1 of Example 1. 500 mL of industrial fluoride-containing wastewater with an initial fluoride ion concentration of 10.0 mg / L and pH=7.0 was taken, and 200 mg / L of CP-2 was added. Adsorption was carried out at 25℃ and 150 rpm for 20 min with shaking. The test showed that the fluoride ion concentration in the effluent decreased to 1.30 mg / L. Subsequently, 120 mg / L of sodium dodecyl sulfate was added to the water sample, and the sample was transferred to a pressurized dissolved air flotation device to achieve solid-liquid separation. The scum was collected, desorbed with 0.05 mol / L NaOH solution, washed with deionized water, and dried under vacuum at 60°C. After being recycled 5 times, the adsorption capacity of the adsorbent carrier was retained at 75%.
[0059] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.
Claims
1. A controllable morphology MOF adsorbent, characterized in that, The adsorption carrier is composed of a first morphology MOF crystal and a second morphology MOF crystal, wherein the first morphology is a three-dimensional network structure, the second morphology is a micron rod structure, and the MOF crystal has a metal center for targeted adsorption.
2. The controllable morphology MOF adsorbent according to claim 1, characterized in that, The mass ratio of the three-dimensional mesh structure MOF crystal to the micron rod-shaped MOF crystal is 1:5 to 5:
1.
3. The controllable morphology MOF adsorbent according to claim 1, characterized in that, The targeted adsorption metal is lanthanum.
4. A method for preparing a controllable morphology MOF adsorbent as described in any one of claims 1-3, characterized in that, The preparation method includes the following steps: adding the adsorption functional targeting agent and organic linker to the structure directing agent, carrying out a solvothermal reaction, and then taking the reaction product for filtration, washing, drying and sieving to obtain two target morphologies of MOF adsorbent carriers, namely a three-dimensional network structure and a micron rod structure, respectively. Finally, the two target morphologies of MOF adsorbent carriers are combined.
5. The method for preparing a controllable morphology MOF adsorbent according to claim 4, characterized in that, The adsorption-targeting agent is at least one of lanthanum chloride, lanthanum carbonate, lanthanum nitrate, and lanthanum sulfate.
6. The method for preparing a controllable morphology MOF adsorbent according to claim 4, characterized in that, The organic linker is at least one of terephthalic acid, 2-aminoterephthalic acid, and trimesic acid, and the structure directing agent is at least one of N,N-dimethylformamide, formic acid, and acetic acid.
7. The method for preparing a controllable morphology MOF adsorbent according to claim 4, characterized in that, The solvothermal reaction refers to first dispersing the mixture by ultrasonication at 40~200 W power for 5~30 min to form a mixed solution, and then placing the mixed solution in a solvothermal reaction at 120~220℃ for 10~72 h; The washing refers to washing with at least one washing solvent selected from N,N-dimethylformamide, methanol, ethanol or acetone; The drying refers to vacuum drying at 60~130℃; The sieving refers to sieving using standard molecular sieves, and the particle size distribution range of the two target morphologies of MOF adsorbents obtained by sieving is 30~120 μm and 150~400 μm.
8. A method for defluorination of a controllable morphology MOF adsorbent carrier as described in any one of claims 1-3, characterized in that, The specific process of the defluorination application is as follows: the adsorbent carrier is added to the fluoride-containing water body at a dosage of 50~800 mg / L, and after adsorption for 5~210 min, a surfactant is added and flotation separation is performed. The separated adsorbent carrier is desorbed and regenerated for recycling.
9. The application of the controllable morphology MOF adsorbent carrier for fluoride removal according to claim 8, characterized in that, The fluoride-containing water body is industrial fluoride-containing wastewater, high-fluoride groundwater, or high-fluoride geothermal water, and the fluoride ion concentration of the water body after treatment is less than 1.0 mg / L. The adsorption carrier is recycled at least 5 times and has an adsorption capacity of more than 85%.
10. The application of the controllable morphology MOF adsorbent carrier for fluoride removal according to claim 8, characterized in that, The surfactant is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, α-olefin sulfonate, or sodium lauryl ether sulfate. The flotation separation is carried out in a pressurized dissolved air flotation device; The desorbent used in the desorption and regeneration process is at least one of hydrochloric acid, sodium hydroxide solution, sodium chloride solution, or sodium bicarbonate solution with a concentration of 0.01~1 mol / L.