Electrochemical synthesis method of iron-based pacs-MOF and application of iron-based pacs-MOF in organic dye adsorption
The rapid synthesis of iron-based PACS-MOF materials via electrochemical methods solves the problems of long synthesis time and low adsorption efficiency in traditional methods, achieving efficient adsorption of anionic dyes, especially efficient removal of methyl red, and has potential applications in environmental remediation.
Patent Information
- Application Number
- CN202511794679.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-02
- Publication Date
- 2026-02-10
AI Technical Summary
Existing methods for synthesizing iron-based PACS MOFs are time-consuming and require high temperatures, and traditional adsorption materials are inefficient at removing organic dye contamination, especially anionic dyes.
Iron-based PACS-MOFs were synthesized at 60 °C using an electrochemical method. The process involved ultrasonic treatment of terephthalic acid, 2,4,6-tris(4-pyridyl)-1,3,5-triazine, and tetrabutylammonium bromide in DMF and ethanol solvents, followed by electrochemical reaction, centrifugation, and activation treatment to prepare iron-based PACS-MOF materials with rough particle surfaces.
Rapid synthesis of iron-based PACS-MOF materials was achieved, significantly shortening the preparation time. The maximum adsorption capacity of the material for the anionic dye methyl red reached 997 mg/g, with a removal efficiency exceeding 90%, and it exhibits good recyclability.
Smart Images
Figure CN121496416A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of MOF synthesis and dye adsorption, and particularly relates to an electrochemical synthesis method of an iron-based pacs-MOF and application of the iron-based pacs-MOF in organic dye adsorption. BACKGROUND
[0002] The iron-based pacs-MOF is considered as a porous material with great development potential due to its cationic framework characteristics, unique porosity and atomically adjustable physicochemical properties. However, the commonly used synthesis method has the disadvantages of long time (usually > 24 h) and high synthesis temperature (high temperature of 120 ~ 180 ℃).
[0003] Organic dyes are widely used in the textile printing and dyeing, plastic and other industries. The wastewater generated by these industries contains a large amount of organic dyes, which are not only highly toxic but also difficult to biodegrade. Such wastewater not only poses a serious threat to human health, but also consumes a large amount of dissolved oxygen in water, threatening the survival of aquatic organisms, and further leading to water pollution and destruction of the entire ecological system. Therefore, developing new and efficient adsorption materials has become the key to solving the problem of organic dye pollution, and has important practical significance. SUMMARY
[0004] In view of the deficiencies of the prior art, the application provides an electrochemical synthesis method of an iron-based pacs-MOF and application of the iron-based pacs-MOF in organic dye adsorption.
[0005] The application is implemented by the following technical solutions: The electrochemical synthesis method of the iron-based pacs-MOF comprises the following steps: S1, terephthalic acid, 2,4,6-tris(4-pyridyl)-1,3,5-triazine and tetrabutylammonium bromide are added to a mixed solvent of DMF and ethanol, acetic acid is added, and the obtained mixed raw materials are subjected to ultrasonic treatment to uniformly mix the raw materials; S2, iron sheets are used as the cathode and anode, the uniformly mixed solution of S1 is used as the electrolyte, the electrodes are fixed, and electrochemical reaction is performed; S3, after the reaction is completed, the reaction solution is centrifuged at a speed of 3000 r / min for 5 min, the supernatant is removed after centrifugation, ethanol is added to the centrifuge tube, activation treatment is performed, and the sample is obtained after drying after the activation is completed.
[0006] Further, the electrochemical reaction is performed at a constant temperature of 60 ℃ for 3 hours, the voltage is set to 5 V, and the current is set to 2 A.
[0007] Further, the amount-of-substance ratio of terephthalic acid, 2,4,6-tris(4-pyridyl)-1,3,5-triazine and tetrabutylammonium bromide is 3:1:2.6.
[0008] Further, the volume ratio of DMF and ethanol in the mixed solvent is 1.7:6.7, and the addition amount of the mixed solvent is limited to 8.4 mL of mixed solvent corresponding to 0.1 mmol of 2,4,6-tris(4-pyridyl)-1,3,5-triazine.
[0009] Further, the addition amount of acetic acid is limited to 0.8-1.6 mL of acetic acid corresponding to 0.1 mmol of 2,4,6-tris(4-pyridyl)-1,3,5-triazine.
[0010] Further, the addition amount of acetic acid is limited to 1.2 mL of acetic acid corresponding to 0.1 mmol of 2,4,6-tris(4-pyridyl)-1,3,5-triazine.
[0011] The application also provides an iron-based pacs-MOF synthesized by the electrochemical synthesis method of the iron-based pacs-MOF. The particle size of the iron-based pacs-MOF is between 1 µm and 2 µm. The surface of the particle is rough, and there are thorn-like protrusions. The BET specific surface area is 545 m 2 / g, and the pore size distribution is 0.3-1.2 nm.
[0012] The application also provides an application of the iron-based pacs-MOF in dye adsorption.
[0013] Further, the dye is methyl red, and the maximum adsorption capacity is 997 mg / g.
[0014] The application also provides a dye wastewater treatment method, wherein 5-15 mg of iron-based pacs-MOF material is added to 20 mL of 150 mg / L methyl red aqueous solution, and the adsorption is static for 2-24 hours.
[0015] Further, the addition amount of the iron-based pacs-MOF material is 5 mg of MOF.
[0016] Further, the iron-based pacs-MOF material can be recycled.
[0017] The application has the beneficial technical effects that the application uses an electrochemical method to realize the rapid synthesis of iron-based pacs MOF material at 60 ℃ for 3 hours. Compared with the traditional synthesis method, the material preparation time is significantly shortened. The organic dye adsorption test is performed on the synthesized pacs topological MOF material, and the results show that the material can selectively capture anionic dye methyl red, the maximum adsorption capacity reaches 997 mg / g, the removal efficiency is more than 90%, and there is no adsorption effect on cationic dye methylene blue. This shows that the material has certain application potential in organic dye pollution treatment. BRIEF DESCRIPTION OF DRAWINGS
[0018] Figure 1 Synthetic device schematic diagram of the present application; Figure 2 XRD diffraction spectrum of the iron-based pacs type MOF material prepared in Example 1; Figure 3 Thermogravimetric diagram of the iron-based pacs type MOF material prepared in Example 1, and the right figure is a sample display diagram; Figure 4 SEM diagram of the iron-based pacs type MOF material prepared in Example 1; Figure 5 EDS-Mapping diagram of the iron-based pacs type MOF material prepared in Example 1; Figure 6 N2 adsorption-desorption curve (a) and pore size distribution diagram (b) of the iron-based pacs type MOF material prepared in Example 1; Figure 7 Selective adsorption UV monitoring schematic diagram of the iron-based pacs type MOF material prepared in Example 1 on methylene blue (left) and methyl red (right); Figure 8 Schematic diagram of the adsorption effect of the iron-based pacs type MOF material prepared in Example 1 on a mixed solution; Figure 9 Effect of different amounts of iron-based pacs type MOF material on methyl red adsorption; Figure 10 Adsorption isotherm model of the iron-based pacs type MOF material prepared in Example 1; Figure 11 Removal efficiency curve diagram (left) and UV monitoring schematic diagram (right) during the adsorption process of the iron-based pacs type MOF material prepared in Example 1; Figure 12 Pseudo-second-order adsorption kinetics model diagram; Figure 13 Cyclic regeneration schematic diagram (a), after adsorption (b), and after desorption (c) of the iron-based pacs type MOF material prepared in Example 1. DETAILED DESCRIPTION
[0019] Example 1 Terephthalic acid (0.05 g, 0.3 mmol), 2,4,6-tris(4-pyridyl)-1,3,5-triazine (0.0313 g, 0.1 mmol), tetrabutylammonium bromide (0.0835 g, 0.26 mmol) were weighed with an electronic balance, and DMF (1.7 mL), ethanol (6.7 mL), acetic acid (1.2 mL) were pipetted. The weighed raw materials were sequentially added to the reactor, and ultrasonic treatment was performed in an ultrasonic cleaner for 3 h. Ultrasonic agitation was used to promote the uniform mixing of the raw materials to meet the subsequent experimental requirements.
[0020] After mixing evenly, the pre-prepared electrode was carefully inserted into the solution, and a fixing device was used to ensure the stability of the electrode position in the solution. Then, the reaction device was placed in a water bath, the temperature was set to 60 ℃, and the power was turned on after fixing the device. The constant voltage was 5 V, the current was 2 A, and the device was shaken regularly. The reaction lasted for 3 h.
[0021] After 3 h of reaction, the reaction solution in the reactor was slowly and carefully transferred to a centrifuge tube using a rubber bulb dropper. The centrifuge tube was then placed in a centrifuge, and the speed was set to 3000 r / min for 5 min. After the centrifugation process was completed, the supernatant was carefully removed from the centrifuge tube using a rubber bulb dropper. Then, ethanol was slowly added to the centrifuge tube until the liquid level reached about one-third of the centrifuge tube. The centrifuge tube was then left to stand, and ethanol was added as needed to maintain the activation state. The synthesis device is shown in Figure 1 .
[0022] Example 2 Example 2 and Example 1 differ in that the amount of acetic acid added is 0.8 mL, and the rest of the conditions are exactly the same.
[0023] Example 3 Example 3 and Example 1 differ in that the amount of acetic acid added is 1.6 mL, and the rest of the conditions are exactly the same.
[0024] Examples 1-3 are based on the acidity control strategy to explore the influence of different acidity conditions on the synthesis of iron-based pacs type MOF materials. By designing comparative experiments and comprehensively using XRD, SEM and other characterization methods for analysis. The results show that when using 1.2 mL of acetic acid to control the acidity of the system, the prepared iron-based pacs type MOF material shows the best performance in structure, target performance, etc. Based on this, the invention focuses on the experimental and characterization results under this optimal condition, and does not repeat the related data of other amounts of acetic acid.
[0025] (1) Powder X-ray diffraction analysis The powder X-ray diffraction (XRD) characterization results are as follows: Figure 2As shown in Figure 5, the characteristic peaks of the iron-based pacs type MOF material are shown in comparison with the simulated XRD pattern. The synthesized iron-based pacs type MOF material has characteristic peaks at 5.86°, 8.34°, 10.45°, corresponding to (1 0 0), (1 0 1) and (2 -1 0) crystal planes, respectively, which are consistent with the simulated peaks, indicating that the iron-based pacs type MOF material has been successfully synthesized. In addition, it can be seen from the figure that the curve has multiple clear and sharp diffraction peaks, which indicates that the sample has good crystallinity.
[0026] (2) Thermogravimetric analysis The thermogravimetric characterization results are shown in Figure 6 (left). The iron-based pacs type MOF material after solvent exchange with ethanol is relatively stable in mass at 25 ~ 200℃, which is the thermal stability region of the MOF material structure. The first weight loss occurs between 200 ~ 400℃, which may be due to the removal of the solvent. The mass continues to decrease in the temperature range of 400 ~ 600℃, but the rate slows down. This process may be the decomposition of terephthalic acid and 2,4,6-tris(4-pyridyl)-1,3,5-triazine ligand, and the main framework of the compound also begins to collapse. After 600℃, it gradually stabilizes, with a remaining mass of about 20 ~ 30%. Figure 3
[0027] (3) Scanning electron microscope analysis The scanning electron microscope (SEM) image is shown in Figure 7. When the acetic acid addition amount is 1.2 mL, the sample morphology is irregular particles with a particle size of 1 µm ~ 2 µm. The particle surface is rough and has thorn-like protrusions. EDS-Mapping characterization (Figure 8) shows that O, N, and Fe elements are uniformly distributed on the surface of the synthesized iron-based pacs type MOF material. Figure 4 Figure 5
[0028] (4) Specific surface area analysis Figure 6 The nitrogen adsorption-desorption curve and pore size distribution of the iron-based pacs type MOF material regulated by 1.2 mL of acetic acid are shown in Figure 9. It can be seen from the figure that the curve presents a typical I-type isotherm characteristic, belonging to microporous structure. At low relative pressure (P / P0), the adsorption amount increases rapidly, indicating that there are a large number of microporous structures in the material, and gas molecules can quickly fill these micropores. With the increase of relative pressure, the adsorption amount gradually tends to be stable. The maximum nitrogen adsorption amount of the iron-based pacs type MOF material powder synthesized in the experiment is 236 cm 2 / g at 77 K and P / P0=0.99 pressure, and the BET specific surface area obtained from the adsorption data is 545 m 2 / g, and the pore size distribution is in the range of 0.3 ~ 1.2 nm.
[0029] Table 1, iron-based pacs type MOF material characteristics table
[0030] Example 4 dye adsorption test 5 mg of iron-based pacs type MOF material was added to 20 mL of 50 mg / L methylene blue aqueous solution, respectively, and adsorbed for a period of time, and then ultraviolet monitoring was performed.
[0031] As Figure 7 shown, the contrast results of iron-based pacs type MOF material before and after selective adsorption of dyes show that the material exhibits excellent adsorption performance for methyl red, and the adsorption effect for methylene blue is obviously weaker. In addition, after mixing 10 mL of 10 mg / L methylene blue solution with 10 mL of 250 mg / L methyl red solution and performing the adsorption experiment Figure 8 ), the results show that the characteristic peak of methylene blue after adsorption is basically unchanged, and the characteristic peak of methyl red is almost completely disappeared. According to the above experimental data, it can be known that the iron-based pacs type MOF material has significant adsorption selectivity advantage for anionic dye methyl red. Based on this, methyl red will be selected for subsequent batch adsorption experiments.
[0032] As Figure 9 shown, the influence of different amounts of iron-based pacs type MOF material on the adsorption performance of methyl red was explored. In the exploration experiment, methyl red solution with a concentration of 150 mg / L was prepared. The experiment selected 20 mL of the solution as the reaction system, and added 5 mg, 10 mg and 15 mg of iron-based pacs type MOF material into it, respectively. After 4 hours, the adsorption effect of iron-based pacs type MOF material on methyl red solution under different amounts was observed and recorded. As shown in the figure, with the increase of concentration, the adsorption capacity of iron-based pacs type MOF material with three different amounts increased, and under the same concentration, the unit adsorption capacity of 5 mg of iron-based pacs type MOF material was higher than that of 10 mg and 15 mg. The lower left corner of the picture is in turn without MOF, adding 15 mg MOF, adding 10 mg MOF, and adding 5 mg MOF. From the color change in the picture, it can be seen that the adsorption effect of 5 mg of iron-based pacs type MOF material is the best. Therefore, the amount of iron-based pacs type MOF material for subsequent methyl red adsorption performance experiment is selected as 5 mg.
[0033] The adsorption isotherm was studied in the experiment, taking methyl red solution as the research object, and the influence of adsorbate concentration on the adsorption behavior of methyl red at room temperature was investigated. The experimental data was fitted by Langmuir and Freundlich models. Figure 10 It can be obtained that the correlation coefficient R2 0.97; Langmuir model R 2 0.99, indicating that the adsorption mode of the iron-based pacs type MOF material conforms to the Langmuir monolayer adsorption characteristics.
[0034] Table 2, Langmuir and Freundlich model isotherm fitting parameters
[0035] The experimental data of the adsorption amount changing with time were measured, and the pseudo-second-order kinetic model was used to describe the adsorption process. It can be seen from Figure 11 that after adding the iron-based pacs type MOF material, the characteristic peak of methyl red rapidly decreases, and the removal rate reaches 90.69% at 15 min, and then maintains stable. It can be seen from Figure 12 that the adsorption process of the iron-based pacs type MOF material on methyl red conforms to the pseudo-second-order kinetic model, and the pseudo-second-order rate constant can be obtained from the intercept 0.041 g / (mg / min), the equilibrium adsorption capacity is 137 mg / g from the slope, and the correlation coefficient reaches 0.99.
[0036] Table 3, adsorption kinetics parameters of the iron-based pacs type MOF material
[0037] Cyclic regeneration experiment The methyl red molecules in the 1.2 mL acetic acid regulated iron-based pacs type MOF material were desorbed by ethanol, and the desorbed methyl red solution was dried in an oven, and after drying, the adsorption was continued under the same conditions, and the same experiment was repeated for 5 times.
[0038] The sample after dye adsorption is shown in Figure 13 (b), which is reddish brown, and after ethanol elution and activation, the color is black green as shown in Figure 13 (c), and the methyl red adsorption test is carried out again. After 5 cycles, the removal rate of methyl red is about 90.80%. The results show that the adsorption of the iron-based pacs type MOF material on methyl red can be reused.
[0039] In this study, an electrochemical method was developed to realize the rapid synthesis of iron-based MOF materials with pacs topology at 60℃ for 3 hours. Compared with traditional synthesis methods, this method significantly reduces energy consumption and shortens material preparation time, making important progress in the efficiency and energy consumption control of material synthesis. The synthesized MOF materials with pacs topology were tested for organic dye adsorption, and the results showed that they could selectively capture anionic dye methyl red, with a maximum adsorption capacity of 997 mg / g and a removal efficiency of over 90%. However, there was no adsorption effect on cationic dye methylene blue. This indicates that the material has certain application potential in organic dye pollution treatment and can provide support for solving the problem of organic dye pollution in the environment, having important practical significance in environmental governance.
Claims
1. An electrochemical synthesis method for iron-based pacs-MOFs, characterized in that: Includes the following steps: S1. Add terephthalic acid, 2,4,6-tris(4-pyridyl)-1,3,5-triazine, and tetrabutylammonium bromide to a mixed solvent of DMF and ethanol, add acetic acid, and sonicate the resulting mixture to ensure uniform mixing. S2. Using iron sheets as the anode and cathode, and a uniformly mixed solution of S1 as the electrolyte, the electrodes are fixed to carry out an electrochemical reaction. S3. After the reaction is complete, centrifuge the reaction solution at a speed of 3000 r / min for 5 min. After centrifugation, remove the supernatant, add ethanol to the centrifuge tube for activation, and dry after activation to obtain the sample.
2. The electrochemical synthesis method of iron-based pacs-MOF according to claim 1, characterized in that: The electrochemical reaction was carried out under constant temperature of 60 °C for 3 hours with an electric current of 5 V and a current of 2 A.
3. The electrochemical synthesis method of iron-based pacs-MOF according to claim 1, characterized in that: The molar ratio of terephthalic acid, 2,4,6-tris(4-pyridyl)-1,3,5-triazine, and tetrabutylammonium bromide is 3:1:2.
6.
4. The electrochemical synthesis method of iron-based pacs-MOF according to claim 1, characterized in that: The volume ratio of DMF to ethanol in the mixed solvent is 1.7:6.7, and the amount of mixed solvent added is limited to 0.1 mmol of 2,4,6-tris(4-pyridyl)-1,3,5-triazine corresponding to 8.4 mL of mixed solvent.
5. The electrochemical synthesis method of iron-based pacs-MOF according to claim 1, characterized in that: The amount of acetic acid added is limited to 0.1 mmol of 2,4,6-tris(4-pyridyl)-1,3,5-triazine, corresponding to 0.8-1.6 mL of acetic acid.
6. The electrochemical synthesis method of iron-based pacs-MOF according to claim 1, characterized in that: The amount of acetic acid added is limited to 0.1 mmol of 2,4,6-tris(4-pyridyl)-1,3,5-triazine corresponding to 1.2 mL of acetic acid.
7. An iron-based pacs-MOF synthesized by the synthesis method according to any one of claims 1-6, characterized in that: The iron-based pacs-MOF particles have a size between 1 µm and 2 µm, a rough surface with spiky protrusions, and a BET specific surface area of 545 m². 2 / g, with a pore size distribution of 0.3~1.2 nm.
8. The application of an iron-based pacs-MOF synthesized by any one of claims 1-6 in dye adsorption, characterized in that: The dye is methyl red.
9. The application of the iron-based pacs-MOF in dye adsorption according to claim 8, characterized in that: The iron-based pacs-MOF material can be recycled.
10. The application of the iron-based pacs-MOF in dye adsorption according to claim 8, characterized in that: The method for dye adsorption using iron-based pacs-MOF includes the following steps: add 5-15 mg of iron-based pacs-MOF material to 20 mL of 150 mg / L methyl red aqueous solution and allow it to stand for 2-24 hours for adsorption.