Preparation method and application of porous structure CuFe2O4
By preparing a porous CuFe2O4 catalyst and utilizing its activation of sulfite to generate strong oxidizing free radicals, the problems of stability and recycling difficulties in existing technologies have been solved, achieving efficient and economical degradation of organic pollutants.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIAMEN UNIV OF TECH
- Filing Date
- 2024-03-13
- Publication Date
- 2026-06-23
AI Technical Summary
In the existing technology, the advanced oxidation technology based on transition metal activated persulfate has problems such as poor structural stability, easy agglomeration, high leaching, difficulty in recycling and high cost. In addition, sulfites are highly toxic, which limits their application in the field of water treatment.
By using a porous CuFe2O4 catalyst and controlling the molar ratio of copper salt and iron salt as well as the proportion of pore-forming agent, a magnetic and porous CuFe2O4 catalyst was prepared. This catalyst was then used to activate sulfite to generate highly efficient hydroxyl radicals and sulfate radicals, thereby degrading organic pollutants.
It achieves efficient, rapid, and recyclable degradation of organic pollutants, with a degradation efficiency of up to 100%, low cost, and suitability for large-scale production, meeting the requirements of sustainable development.
Smart Images
Figure CN117985768B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of water pollution treatment technology, and in particular to a method for preparing porous CuFe2O4 and its application. Background Technology
[0002] For emerging pollutants, the main degradation and transformation technologies currently employed include physical, biological, and chemical methods, but each has its limitations. Commonly used physical methods mainly include adsorption and membrane filtration. Their advantages include simple operation, good treatment effect, and low likelihood of generating harmful byproducts. However, adsorption suffers from adsorption saturation, non-renewable adsorbents, and the adsorption effect is largely determined by the adsorbent and the type of pollutant. Membrane filtration has limitations, such as its inability to destroy the structure of pollutants. Biological treatment methods are more economical than physical and chemical methods, enabling resource utilization during wastewater treatment. However, they have a significant impact on water quality and are less effective at removing low concentrations of organic pollutants. Chemical methods primarily utilize oxidation-reduction reactions to convert recalcitrant organic pollutants into stable, low-toxicity, or non-toxic small-molecule compounds. Commonly used chemical oxidation methods for treating organic wastewater include photochemical oxidation, electrochemical oxidation, and advanced oxidation methods.
[0003] Advanced oxidation technologies mainly include those based on hydroxyl radicals (HO·) and sulfate radicals (SO4·). − Advanced oxidation technology for SO4·. Compared to H2O·, SO4· − Its redox potential (2.5-3.1V) is higher. Based on SO4• − Advanced oxidation technologies (AOPs) can remove most organic pollutants, including SO4. − It is mainly produced through the activation of persulfate (PMS) or perdisulfate (PDS). Currently, most research focuses on transition metal-activated PMS. However, the transition metal / PMS system has the following problems: ① poor structural stability, easy agglomeration, and high leaching; ② difficulty in recycling non-magnetic materials; ③ high cost and certain toxicity of PMS. This limits its application in the field of water treatment. Summary of the Invention
[0004] The purpose of this application is to address the shortcomings of current technologies by providing a method for preparing porous CuFe2O4 and its applications. The porous CuFe2O4 prepared in this application has advantages such as structural stability, magnetic properties, and recyclability. Furthermore, it uses inexpensive and less toxic sulfite (S(IV)) instead of PMS to construct H2O· and SO4· − The coexisting CuFe2O4 / S(Ⅳ) system can efficiently degrade organic pollutants in water.
[0005] In a first aspect, this application provides a method for preparing porous CuFe2O4, employing the following technical solution:
[0006] A method for preparing porous CuFe2O4 includes the following steps:
[0007] Copper salt, iron salt, and pore-forming agent are stirred and mixed, and then ground into a gel-like product. The gel-like product is then calcined for 1.5-3 hours, naturally cooled to below 100°C, and finally thoroughly ground and sieved to obtain a porous CuFe2O4 structure. The molar ratio of copper salt to iron salt is 1:2-2.1, and the molar ratio of copper salt to pore-forming agent is 1:1.5-1.55.
[0008] By adopting the above technical solution, the molar ratio of copper salt to iron salt is 1:2-2.1, which can effectively increase the number of active sites in the porous CuFe2O4 structure, thereby improving its efficiency in activating sulfite and degrading organic pollutants. Simultaneously, the molar ratio of copper salt to pore-forming agent is 1:1.5-1.55, which can increase the role of the pore-forming agent in the preparation process and help form a uniform porous structure. During the preparation process, grinding the gel-like product helps increase the specific surface area of the material, which is beneficial for the exposure of active sites and the transport of substances. Natural cooling to below 100℃ after calcination can prevent the material structure from being damaged by excessively high temperatures, maintaining the stability of its porous structure. Finally, thorough grinding and sieving ensure the acquisition of a uniform porous CuFe2O4 structure, improving its efficiency in degrading organic pollutants. In summary, the components play a synergistic role in the preparation of the porous CuFe2O4 structure in this application, jointly affecting the performance and activity of the porous CuFe2O4 structure, enabling it to efficiently activate sulfite and degrade organic pollutants. Furthermore, the preparation method is simple to operate, low in cost, and suitable for industrialization.
[0009] Preferably, the molar ratio of the copper salt to the iron salt is 1:2; and the molar ratio of the copper salt to the pore-forming agent is 1:1.5.
[0010] Preferably, the iron salt is one or more of ferric chloride, ferric nitrate, and ferric sulfate.
[0011] Preferably, the copper salt is one or more of copper nitrate, copper sulfate, and copper dichloride.
[0012] Preferably, the pore-forming agent is one of citric acid and ethylenediaminetetraacetic acid.
[0013] Preferably, the calcination process conditions are: heating to 400-430℃ at a heating rate of 2-5℃ / min.
[0014] Preferably, the particle size of the porous CuFe2O4 structure is 0.5-1 micrometer.
[0015] By employing the above-mentioned technical solution, the 0.5-1 micrometer particle size of porous CuFe2O4 plays a crucial role. Firstly, porous CuFe2O4 with a particle size in the nanoscale range has a larger specific surface area, which is beneficial for increasing the exposure of active sites and reaction rate. This means more active sites are exposed on the surface, thereby increasing the contact area with the target pollutant and improving catalytic degradation efficiency. Secondly, a particle size of 0.5-1 micrometer can improve the stability and recyclability of porous CuFe2O4. Smaller particle size helps improve the magnetic properties of the material, making it easier to recycle under an applied magnetic field. Simultaneously, particle size uniformity also helps improve the uniformity and stability of the material during the reaction, further enhancing degradation efficiency.
[0016] Preferably, the stirring speed is 300-500 r / min and the stirring time is 20-30 min.
[0017] Secondly, this application provides an application of a method for preparing porous CuFe2O4, employing the following technical solution:
[0018] As a general technical concept, this application also provides the application of the porous CuFe2O4 obtained by the above-mentioned method for preparing porous CuFe2O4 as a catalyst for activating sulfite degradation of organic pollutants.
[0019] Preferably, the pollutant degradation system has the following characteristics: pollutant concentration of 0.5 mg / L, sulfite concentration of 250 μM, CuFe2O4 concentration of 0.45 g / L, pH of 6-8, reaction time of 2-3 min, and liquid volume of 100 mL.
[0020] Preferably, the contaminant is caffeine.
[0021] By employing the above-mentioned technical solution, porous CuFe₂O₄ plays a crucial role in the activation of sulfites and the efficient degradation of caffeine. Porous CuFe₂O₄ possesses abundant active sites and a high specific surface area, facilitating effective contact with sulfites and promoting their activation and decomposition. During the reaction, the active sites on the CuFe₂O₄ surface rapidly catalyze sulfites, generating highly oxidizing free radicals such as SO₄•− and HO•, which initiate a series of free radical reactions, promoting the rapid oxidative decomposition of sulfites. The high specific surface area of porous CuFe₂O₄ effectively exposes active sites, facilitating contact with organic pollutants such as caffeine and promoting its oxidative degradation. The highly oxidizing free radicals generated by CuFe₂O₄ catalyzing the activation of sulfites, such as SO₄•− and HO•, possess high oxidizing power and can directly oxidize and degrade the easily oxidized parts of the caffeine molecule. Furthermore, in the CuFe2O4 / (S(Ⅳ)) system, SO4•− can react with water or hydroxide ions to generate HO•, further accelerating the oxidative degradation of caffeine. The resulting CuFe2O4 has more active sites, exhibiting a significant catalytic activation effect on sulfites, a high reaction rate, and consequently, improved degradation efficiency. Under existing experimental conditions, caffeine concentration can be rapidly degraded from 0.5 mg / L in a short time (3 min), with a degradation efficiency of 100%. The CuFe2O4 / (S(Ⅳ)) system demonstrates higher degradation efficiency and rate, and is more effective in activating sulfites. In summary, porous CuFe2O4 achieves rapid, efficient, and sustainable degradation of organic pollutants through the exposure of active sites and the generation of strong oxidizing free radicals during the efficient activation of sulfites and degradation of caffeine, providing a green and efficient new approach for treating organic pollutants in water.
[0022] In summary, the beneficial technical effects of this application are as follows:
[0023] 1. Highly Efficient Sulfite Activation: The porous structure of CuFe₂O₄, with its abundant active sites, high specific surface area, and porous structure, is beneficial for improving the efficiency and rate of sulfite activation, thus promoting the degradation of organic pollutants. Under optimized conditions in the preparation method, CuFe₂O₄ can generate highly oxidizing free radicals, such as SO₄•− and HO•, thereby effectively activating sulfite and initiating a series of free radical reactions, rapidly converting organic pollutants into harmless products.
[0024] 2. Highly Efficient Degradation of Organic Pollutants: Under specified reaction conditions, porous CuFe2O4 exhibits highly efficient performance in degrading organic pollutants, especially model pollutants such as caffeine. Various reactive free radicals generated in the CuFe2O4 / (S(Ⅳ)) system undergo oxidation reactions with organic pollutants, thereby achieving their degradation and providing an efficient and green solution for environmental protection.
[0025] 3. Technological and economic benefits: The preparation method provided in this application is simple to operate, low in cost, and can be scaled up for large-scale production, reducing processing costs. CuFe2O4, as a magnetic recyclable material, can be easily recycled and reused, reducing waste emissions and resource waste, which meets the requirements of sustainable development.
[0026] 4. Traditional gel-sol method for preparing CuFe2O4 does not have multiple active sites and cannot activate sulfites. This application can prepare CuFe2O4 with multiple active sites, which can efficiently activate sulfites and effectively solve organic pollutants.
[0027] 5. Compared to PMS, sulfites (S(Ⅳ)) are cheaper and less toxic. Attached Figure Description
[0028] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below:
[0029] Figure 1 SEM image of CuFe2O4 prepared by sol-gel method in Comparative Example 1;
[0030] Figure 2 SEM image of solvent-free CuFe2O4 prepared in Example 4;
[0031] Figure 3 The EPR spectrum of the CuFe2O4 / sodium sulfite system in Application Example 1;
[0032] Figure 4 The graphs show the degradation effects of Application Example 1 and Comparative Examples 1-3. Detailed Implementation
[0033] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this application. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.
[0034] Example 1
[0035] A method for preparing porous CuFe2O4 includes the following steps:
[0036] 0.01 mol copper sulfate, 0.02 mol ferric sulfate and 0.03 mol citric acid were mixed and stirred at 300 r / min for 30 min. The mixture was then ground into a gel-like product. The gel-like product was then placed in a sintering furnace and heated to 400℃ at a heating rate of 2℃ / min for 3 hours. After naturally cooling to 100℃, the product was removed, thoroughly ground and sieved to obtain a porous CuFe2O4 structure with a particle size of 0.5-1 micrometer.
[0037] Example 2
[0038] A method for preparing porous CuFe2O4 includes the following steps:
[0039] 0.01 mol of copper dichloride, 0.021 mol of ferric chloride, and 0.031 mol of ethylenediaminetetraacetic acid were mixed and stirred at a speed of 500 r / min for 20 min. The mixture was then ground into a gel-like product. The gel-like product was then placed in a sintering furnace and heated to 430°C at a heating rate of 5°C / min for 1.5 hours. After naturally cooling to 100°C, the product was removed, thoroughly ground, and sieved to obtain a porous CuFe2O4 structure with a particle size of 0.5-1 micrometer.
[0040] Example 3
[0041] A method for preparing porous CuFe2O4 includes the following steps:
[0042] 0.01 mol copper nitrate, 0.0205 mol ferric nitrate, and 0.0305 mol citric acid were mixed at a stirring speed of 400 r / min for 25 min and ground into a gel-like product. The gel-like product was then placed in a sintering furnace and heated to 420°C at a heating rate of 3°C / min for 2 hours. After naturally cooling to 100°C, the product was removed, thoroughly ground, and sieved to obtain a porous CuFe2O4 structure with a particle size of 0.5-1 micrometer.
[0043] Example 4
[0044] A method for preparing porous CuFe2O4 includes the following steps:
[0045] Combine 8.08gFe(NO3)3·9H2O, 2.416g Cu(NO3) 2·3H2O and 12.06g of citric acid (C6H8O7⋅H2O) were stirred and mixed at a speed of 400r / min for 25min. The mixture was then ground into a gel-like product. The gel-like product was then placed in a sintering furnace and heated to 400℃ at a heating rate of 3℃ / min for 2 hours. After naturally cooling to 100℃, the product was removed, thoroughly ground, and sieved to obtain a porous CuFe2O4 with a particle size of 0.5-1 micrometer, which was labeled as solvent-free CuFe2O4.
[0046] Comparative Example 1: Preparation of CuFe2O4 by Sol-Gel Method
[0047] Weigh 8.08g Fe(NO3)3·9H2O and 2.416g Cu(NO3)2·3H2O, pour them into a 250 mL beaker and add 100mL of ultrapure water. Then place the beaker in a constant temperature water bath at 60℃ and heat and stir for 1 hour. Next, add 6.3g of citric acid and continue stirring and reacting at 60℃ for another hour to obtain a transparent brown liquid. Transfer the liquid to an oven at 90℃ and dry for 12 hours. The liquid turns into a gel. Calcine the gel in a muffle furnace at 300℃ for 4 hours to obtain particles. Grind the particles into powder using an agate grinder and wash them repeatedly with ultrapure water until the washing liquid is neutral. Place the washings in an oven at 105℃ and continue drying for 12 hours. After drying, pseudo-spherical copper-iron spinel is obtained, labeled as CuFe2O4 by sol-gel method.
[0048] Application Example 1: Degradation of Pollutants
[0049] The total process system was 100 mL, using a 100 mL conical flask as the reaction vessel. The degradation system for pollutants was as follows: caffeine concentration of 0.5 mg / L, sodium sulfite concentration of 250 μM, catalyst concentration of 0.45 g / L, pH of 7, and reaction time of 3 min. The catalyst was solvent-free CuFe2O4, which was the sample prepared in Example 4 and labeled as solvent-free CuFe2O4 / sodium sulfite.
[0050] Application Comparative Example 1: Degradation of Pollutants
[0051] The total process system was 100 mL, using a 100 mL conical flask as the reaction vessel. The degradation system for pollutants was as follows: caffeine concentration of 0.5 mg / L, sodium sulfite concentration of 250 μM, catalyst concentration of 0.45 g / L, pH of 7, and reaction time of 3 min. The catalyst was CuFe2O4 prepared by sol-gel method, which was the sample prepared in Comparative Example 1. It was labeled as sol-gel method CuFe2O4 / sodium sulfite.
[0052] Application Comparative Example 2: Degradation of Pollutants
[0053] The total process system is 100 mL, using a 100 mL conical flask as the reaction vessel. The degradation system for pollutants is as follows: caffeine concentration is 0.5 mg / L, catalyst is 0.45 g / L, pH is 7, and reaction time is 3 min. The catalyst is solvent-free CuFe2O4, which is the sample prepared in Preparation Example 4. It is labeled as solvent-free CuFe2O4.
[0054] Application Comparative Example 3: Degradation of Pollutants
[0055] The total process system is 100 mL, using a 100 mL conical flask as the reaction vessel. The degradation system for pollutants is as follows: caffeine concentration of 0.5 mg / L, sodium sulfite concentration of 250 μM, pH of 7, and reaction time of 3 min; labeled as sodium sulfite alone.
[0056] Performance testing
[0057] 1. SEM image
[0058] The sample prepared in Example 4 was analyzed by SEM image analysis, and the results are as follows: Figure 2 As shown, the SEM images of the sample prepared in Comparative Example 1 were analyzed using electron microscopy, and the results are as follows. Figure 1 As shown. From Figure 2 and Figure 1 Comparative analysis shows that the porous CuFe2O4 prepared in this application can activate sulfites with high redox potential.
[0059] 2. EPR free radical detection
[0060] Using DMPO as the capture agent, the active species in the CuFe2O4 / sodium sulfite system corresponding to Example 1 were captured, and the results are as follows: Figure 3 As shown. From Figure 3 As can be seen, when using EPR for free radical capture (with DMPO as the capture agent), the spectrum shows that both hydroxyl radicals and sulfate radicals are captured simultaneously, indicating that this is a system in which two types of free radicals coexist.
[0061] 3. Degradation test of the contaminant caffeine
[0062] HPLC settings: Inertsustain® C18 column (4.6 mm × 250 mm, 5 μm), mobile phase acetonitrile:water = 20%:80%, flow rate 1.0 mL / min, injection volume 10 μL; detection wavelength λ = 243 nm, column oven 40 °C.
[0063] After degradation of Application Example 1 and Comparative Examples 1-3, caffeine concentration was tested according to HPLC settings. The test results are as follows: Figure 4 As shown. From Figure 4 As can be seen, the CuFe2O4 sample prepared in Example 4 is the target of caffeine degradation. Using high performance liquid chromatography, the degradation efficiency of caffeine by this process is 100% within 3 minutes, indicating that the process has high degradation efficiency and ultra-high degradation rate.
[0064] The above embodiments are only used to explain the technical solutions of this application and are not intended to limit it. Although the above embodiments have provided specific descriptions of this application, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this invention. Any modifications and equivalent substitutions that do not depart from the spirit and scope of this application should be covered within the protection scope of this application.
Claims
1. A method for preparing porous CuFe2O4, characterized in that, Includes the following steps: Copper salt, iron salt, and pore-forming agent are stirred and mixed, and then ground into a gel-like product. The gel-like product is then calcined for 1.5-3 hours, naturally cooled to below 100°C, and finally thoroughly ground and sieved to obtain a porous CuFe2O4 structure. The molar ratio of copper salt to iron salt is 1:2, and the molar ratio of copper salt to pore-forming agent is 1:1.
5. The pore-forming agent is one of citric acid and ethylenediaminetetraacetic acid; The calcination process conditions are as follows: heating to 400-430℃ at a heating rate of 2-5℃ / min; The stirring speed is 300 r / min, 400 r / min, or 500 r / min, and the stirring time is 20-30 min; The porous CuFe2O4 has a particle size of 0.5-1 micrometer.
2. The method for preparing a porous CuFe2O4 structure according to claim 1, characterized in that, The iron salt is one or more of ferric chloride, ferric nitrate, and ferric sulfate.
3. The method for preparing a porous CuFe2O4 structure according to claim 1, characterized in that, The copper salt is one or more of copper nitrate, copper sulfate, and copper dichloride.