Nanometer flower-shaped cobalt molybdenum oxide catalytic material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of environment restoration functional materials, and particularly relates to a nano flower-shaped cobalt molybdenum oxide catalytic material and a preparation method and application thereof. The preparation method comprises the following steps: by taking cobalt salt, molybdenum salt and urea (carbamide CO (NH2) 2) as reactants, carrying out hydrothermal reaction to obtain a cobalt-molybdenum oxide precursor; and calcining the cobalt molybdenum oxide precursor to obtain the nano flower-shaped cobalt molybdenum oxide catalytic material. According to the nano flower-shaped cobalt molybdenum oxide catalytic material prepared by the method, a large number of gaps exist in particles and among the particles, so that efficient catalysis of peroxymonosulfate and efficient degradation of organic pollutants can be realized.

Description

Technical Field

[0001] This invention belongs to the field of environmental remediation functional materials technology, and more specifically relates to a nano-flower-like cobalt-molybdenum oxide catalytic material, its preparation method and application. Background Technology

[0002] Bisphenol A (BPA), an important organic chemical raw material, is widely used in the production of various polymer materials such as polycarbonate, epoxy resin, and flame retardants. Consequently, BPA is continuously released into the aquatic environment during production, use, and waste disposal, making it one of the most frequently detected persistent organic pollutants in surface water, groundwater, and even drinking water sources. BPA has an endocrine-disrupting effect similar to estrogen; even at extremely low concentrations (ng / L), it can potentially harm the reproductive, developmental, nervous, and immune systems of organisms, and can accumulate and amplify within organisms, threatening ecosystem security and human health. Due to its stable chemical structure and benzene ring content, BPA is difficult to effectively degrade through natural physical, chemical, or biological processes. Therefore, developing efficient, economical, and environmentally friendly deep removal technologies for BPA has become a crucial issue urgently needing to be addressed in the field of environmental remediation.

[0003] Currently, the main technologies for removing BPA from water include physical adsorption, biodegradation, and advanced oxidation. While physical adsorption (such as activated carbon adsorption) can rapidly transfer pollutants, it does not achieve mineralization and suffers from problems such as difficulty in adsorbent regeneration and the potential for secondary pollution. Biodegradation is limited by the biotoxicity of BPA, often resulting in low degradation efficiency, long cycles, and sensitivity to environmental conditions (such as pH, temperature, and coexisting pollutants), thus limiting its application in practical wastewater treatment. In contrast, advanced oxidation technologies based on free radical and non-free radical reactions have attracted significant attention due to their ability to completely degrade and even mineralize BPA.

[0004] Among numerous advanced oxidation technologies, persulfate-based technologies have developed rapidly in recent years. Compared with perdisulfate and hydrogen peroxide, PMS is more easily activated due to its longer peroxy (OO) bonds and unique asymmetric structure. The key to activating PMS to generate reactive oxygen species lies in the development of efficient and stable catalytic materials. Typically, PMS can be activated through homogeneous (thermal activation, base activation, radiation activation, and transition metal ion activation) or heterogeneous (metal oxides, carbon-based materials) methods. Among various heterogeneous catalysts, transition metal oxides (such as cobalt, manganese, and iron oxides) are widely studied due to their high catalytic activity. Cobalt-based catalysts are considered one of the most effective metal oxides for activating PMS. However, single cobalt oxides still face some problems in practical applications: firstly, cobalt ions pose a certain leaching risk during the reaction, potentially causing secondary pollution; secondly, the morphology and structure of the catalytic material directly affect its specific surface area, the degree of exposure of active sites, and the mass transfer efficiency of reactants. Cobalt oxides prepared by traditional methods often suffer from problems such as easy particle agglomeration and limited specific surface area, limiting further improvement in their catalytic performance.

[0005] To overcome the limitations of single-metal oxides, researchers have begun exploring bimetallic or multimetallic oxides. Cobalt-molybdenum oxides, as materials with potential synergistic catalytic effects, benefit from the introduction of Mo, which can modulate the electronic structure of Co, enhance catalyst stability, and potentially provide more active sites. However, existing methods for preparing CoMoO4 often struggle to precisely control the microstructure of the material, resulting in irregular particles or bulk materials with small specific surface areas and poor accessibility of active sites, thus hindering their catalytic activation efficiency for PMS. Therefore, developing a controllable preparation method for CoMoO4 catalytic materials with unique hierarchical structures, high specific surface areas, and abundant active sites is of significant research and application value for significantly improving their performance in activating PMS and degrading BPA, and promoting their application in practical water treatment. Summary of the Invention

[0006] The purpose of this invention is to provide a nano-flower-like cobalt-molybdenum oxide catalytic material, its preparation method, and its application, so as to solve the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of this invention: provides a method for preparing a nano-flower-like cobalt-molybdenum oxide catalytic material, comprising the following steps: Using cobalt salt, molybdenum salt and urea (carbonamide CO(NH2)2) as reactants, a cobalt-molybdenum oxide precursor was obtained through a hydrothermal reaction. The cobalt-molybdenum oxide precursor was calcined to obtain the nano-flower-like cobalt-molybdenum oxide catalytic material.

[0008] Furthermore, the cobalt salt comprises CoSO4•7H2O.

[0009] Furthermore, the molybdenum salt includes (NH4)6Mo7O 24 •4H2O.

[0010] Furthermore, the mass ratio of the cobalt salt, molybdenum salt, and urea is (1.0~1.4):(0.6~1.0):(2.1~32.5).

[0011] Furthermore, the hydrothermal reaction is carried out at a temperature of 120-140°C for 8-10 hours.

[0012] Furthermore, the heating rate of the calcination treatment is 2~5℃ / min, the temperature is 500~650℃, and the holding time is 3~4h.

[0013] Furthermore, the hydrothermal reaction also includes a purification step.

[0014] Optionally, the impurity removal is performed by rinsing with ethanol and water followed by vacuum drying.

[0015] Preferably, the rinsing with ethanol is performed 5-8 times.

[0016] Preferably, the number of times the water is rinsed is 5-8 times.

[0017] Preferably, the vacuum drying temperature is 60~65℃ and the time is 12~14h.

[0018] The second technical solution of the present invention provides a nano-flower-like cobalt-molybdenum oxide catalytic material, which is prepared by the above-described preparation method.

[0019] The third technical solution of the present invention provides an application of the above-mentioned nano-flower-like cobalt-molybdenum oxide catalytic material in the activation of persulfate.

[0020] The fourth technical solution of the present invention provides an application of the above-mentioned nano-flower-like cobalt-molybdenum oxide catalytic material in the degradation of organic pollutants by activated persulfate.

[0021] Furthermore, the organic pollutant includes bisphenol A.

[0022] The fifth technical solution of the present invention provides a method for degrading bisphenol A in organic wastewater, wherein the method uses the above-mentioned nano-flower-shaped cobalt-molybdenum oxide catalytic material to activate persulfate to degrade bisphenol A in organic wastewater.

[0023] The present invention discloses the following technical effects: This invention synthesizes a nano-flower-like cobalt-molybdenum oxide catalytic material via a multi-step method. The reaction conditions are mild, and no toxic or harmful raw materials are involved. The prepared material is highly efficient and environmentally friendly. The prepared nano-flower-like cobalt-molybdenum oxide catalytic material maintains structural integrity while exhibiting excellent catalytic performance. The nano-flower-like cobalt-molybdenum oxide catalytic material prepared by this method has numerous pores within and between its particles, enabling highly efficient catalysis of persulfate and efficient degradation of organic pollutants.

[0024] Through the optimization of the structural design and preparation method of this invention, the prepared nano-flower-like cobalt-molybdenum oxide catalytic material exhibits excellent degradation efficiency in the degradation of BPA by activated persulfate. The degradation rate of BPA can reach 95.22% within 60 minutes, which is much higher than that of cobalt oxide (Co3O4) and molybdenum oxide (MoO3) catalytic materials, and has a high degradation effect on organic pollutants. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 Scanning electron microscope image of the nanoflower-like cobalt-molybdenum oxide catalytic material prepared in Example 1.

[0026] Figure 2 The X-ray diffraction pattern of the nano-flower-like cobalt-molybdenum oxide catalytic material prepared in Example 1 is shown.

[0027] Figure 3 X-ray photoelectron spectroscopy of the nano-flower-like cobalt-molybdenum oxide catalytic material prepared in Example 1.

[0028] Figure 4 The diagram shows the effect of Bisphenol A degradation in Experiments 1 and 2.

[0029] Figure 5 This demonstrates the anti-interference ability of the nano-flower-like cobalt-molybdenum oxide catalytic material prepared in Example 1 during the activation of PMS to degrade BPA. Detailed Implementation

[0030] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0031] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0032] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0033] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0034] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0035] Unless otherwise specified, all raw materials and reagents involved in the specific embodiments of this invention are commercially available products.

[0036] Unless otherwise specified, room temperature and normal temperature in the specific embodiments of this invention refer to 20-30℃.

[0037] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0038] In some specific embodiments, the present invention provides a method for preparing a nano-flower-like cobalt-molybdenum oxide catalytic material, the steps of which include: S1, cobalt salt (CoSO4•7H2O) and molybdenum salt ((NH4)6Mo7O) 24 •4H2O), urea and water are mixed in a mass ratio of (1.0~1.4):(0.6~1.0):(2.1~2.5):200 and magnetically stirred at 450~600 rpm for 30~45 min at 20~25℃ to obtain a mixed solution; Urea can provide alkaline conditions for the reaction, slow down the formation of metal precipitation, reduce material agglomeration, and increase active sites. S2. Transfer the mixed solution obtained in step S1 to a high-pressure reactor and place it in an electric heating drying oven for hydrothermal reaction at 120-140℃ for 8-10 hours. After cooling, filter under vacuum to obtain the cobalt molybdenum oxide precursor. S3. Rinse the cobalt-molybdenum oxide precursor from step S2 with ethanol 5-8 times, then rinse with water 5-8 times, and then vacuum dry at 60-65℃ for 12-14h. After drying, transfer it to a muffle furnace and heat it to 500-650℃ at a heating rate of 2-5℃ / min. Calcinate it at this temperature for 3-4h, and then cool it to room temperature to obtain the nano-flower-like cobalt-molybdenum oxide catalytic material.

[0039] The nano-flower-like cobalt-molybdenum oxide (CM) of this invention exhibits excellent catalytic performance. Its cobalt and molybdenum ions can synergistically activate permonosulfate (PMS) to generate sulfate radicals (SO42-), which have strong oxidizing power. •− The high-valence metal oxygen radicals effectively attack the benzene ring structure in BPA molecules, breaking their chemical bonds and thus degrading BPA. Secondly, the cobalt-molybdenum oxide exhibits a flower-like hierarchical structure formed by the self-assembly of nanosheets, with particle diameters of approximately 1-2 μm. Numerous voids within and between particles facilitate mass transfer and diffusion of reactant molecules, effectively promoting rapid activation of PMS and the transport and diffusion of free radicals, thereby enhancing its BPA removal capacity. Cobalt ions in the cobalt-molybdenum oxide play a crucial role in the degradation reaction, accelerating the reaction rate by enhancing the activation effect of PMS.

[0040] The calcination process can remove organic impurities from the material and enhance its thermal stability and mechanical strength. At the same time, an appropriate calcination temperature can optimize the crystal structure of the material, increase the number of active sites, and improve its activation ability for PMS.

[0041] Example 1 The preparation steps of a nano-flower-like cobalt-molybdenum oxide catalytic material include: S1, 2.25g cobalt salt (CoSO4•7H2O) and 1.41g molybdenum salt ((NH4)6Mo7O) 24 • 4H2O) and 4.81g of urea (CO(NH2)2) were dissolved in 300mL of ultrapure water and magnetically stirred at 600rpm for 30min at 25℃ to obtain a mixed solution; S2. The mixed solution obtained in step S1 is transferred to a high-pressure reactor and placed in a forced-air drying oven for hydrothermal reaction at 120°C for 8 hours. After cooling to 25°C, it is vacuum filtered. The cobalt-molybdenum oxide precursor in step S2 is washed 5 times with ethanol and then washed 5 times with water. Subsequently, it is vacuum dried at 60~65°C for 12~14 hours to obtain the cobalt-molybdenum oxide precursor. S3. The cobalt-molybdenum oxide precursor was transferred to a muffle furnace and heated to 500°C at a heating rate of 2°C / min. It was then calcined at this temperature for 3 hours and cooled to room temperature to obtain a nano-flower-like cobalt-molybdenum oxide catalytic material, denoted as CM.

[0042] Comparative Example 1 The preparation steps of cobalt oxide (Co3O4) catalytic materials are as follows: 4.34 g of CoSO4•7H2O and 4 g of polyvinylpyrrolidone were mixed in a mixture of 20 mL of pure water and 20 mL of ethanol and magnetically stirred for 60 min at a stirring rate of 600 r / min. 100 mL of 0.4 mol / L sodium hydroxide solution was slowly added dropwise to the mixture over 90 min to obtain a suspension. The suspension was transferred to a reaction vessel and heated at 120 °C for 8 h. After cooling to 25 °C, the product was vacuum filtered to obtain a precipitate. The precipitate was washed five times with ethanol and pure water, respectively, and then vacuum dried at 60 °C for 12 h. After thorough grinding, the precipitate was placed in a muffle furnace and heated to 300 °C at a rate of 2 °C / min, held at that temperature for 4 h, and then cooled to 25 °C to obtain a cobalt oxide (Co3O4) catalyst.

[0043] Comparative Example 2 The preparation steps of molybdenum oxide (MoO3) catalytic materials are as follows: 4g of (NH4)6Mo7O 24 • 4H2O was placed in a muffle furnace and heated to 500℃ at a heating rate of 2℃ / min, held for 4h, and then cooled to 25℃ to obtain molybdenum oxide (MoO3) catalyst material.

[0044] Test case Figure 1 The image shows a scanning electron microscope (SEM) image of the nano-flower-like cobalt-molybdenum oxide catalytic material prepared in Example 1. As can be seen from the image, the microstructure of the nano-flower-like cobalt-molybdenum oxide catalytic material prepared in Example 1 exhibits a flower-like hierarchical structure formed by the self-assembly of nanosheets. The particle diameter is approximately 1-2 μm, and there are numerous voids within and between the particles, indicating that the material has been successfully synthesized.

[0045] Figure 2The image shows the X-ray diffraction pattern of the nano-flower-like cobalt-molybdenum oxide catalytic material prepared in Example 1. As can be seen from the image, the structure of the nano-flower-like cobalt-molybdenum oxide catalytic material prepared in Example 1 contains the characteristic peaks of cobalt-molybdenum oxide nanoparticles, indicating that the material has been successfully synthesized.

[0046] Figure 3 The figure shows the X-ray photoelectron spectrum of the nano-flower-like cobalt-molybdenum oxide catalytic material prepared in Example 1. As can be seen from the figure, the characteristic elements of the nano-flower-like cobalt-molybdenum oxide catalytic material prepared in Example 1 contain Co, Mo, and O elements of cobalt-molybdenum oxide nanoparticles, indicating that the material has been successfully synthesized.

[0047] Performance tests of the catalytic materials prepared in the examples and comparative examples: Experiment 1: 100 mL of 10 mg / L BPA solution was added to an Erlenmeyer flask. 0.005 g of catalyst and 0.01 g of permonosulfate (PMS) were added to initiate the reaction. At the set time (60 min), 1.0 mL of the reaction solution was collected, filtered through a nylon syringe filter, and 0.5 mL of the reaction solution was quickly added to a brown vial containing 0.5 mL of methanol. The degradation results are as follows: Figure 4 As shown.

[0048] Experiment 2: 100 mL of a 10 mg / L BPA solution was added to an Erlenmeyer flask, and 0.005 g of catalyst was added to initiate the reaction. At the set time (60 min), 1.0 mL of the reaction solution was collected, filtered using a nylon syringe filter, and then 0.5 mL of the reaction solution was quickly added to a brown vial containing 0.5 mL of methanol. The degradation results are as follows: Figure 4 As shown.

[0049] Figure 4 The figures show the effectiveness of bisphenol A (BPA) degradation in Experiments 1 and 2. As can be seen from the figures, in Experiment 1, the CM prepared in Example 1 can efficiently activate PMS to degrade BPA in water, achieving a degradation rate of up to 95.22% within 60 minutes. The catalytic material prepared in Comparative Example 1 showed a BPA degradation rate of 72.73% within 60 minutes, while the catalytic material prepared in Comparative Example 2 showed a degradation rate of only 2.19% within 60 minutes. In Experiment 2, the CM prepared in Example 1 showed an adsorption rate of only 3.56% for BPA within 60 minutes, indicating that CM cannot rapidly enrich BPA on the catalyst surface to degrade BPA in water.

[0050] Experiment 3: Add 100 mL of 10 mg / L BPA solution to an Erlenmeyer flask, and add different coexisting ions (CO3-) to the system. 2- PO4 3- Cl -The coexisting ion concentrations were all 5 mM. Then, 0.005 g of the nano-flower-like cobalt-molybdenum oxide catalyst (CM) prepared in Example 1 and 0.01 g of permonosulfate (PMS) were added to initiate the reaction. At the set time (60 min), 1.0 mL of the reaction solution was collected, filtered using a nylon syringe filter, and 0.5 mL of the reaction solution was quickly added to a brown vial containing 0.5 mL of methanol. The results of the anti-interference ability are as follows: Figure 5 As shown.

[0051] Figure 5 The figure shows the anti-interference ability of the nano-flower-like cobalt-molybdenum oxide catalytic material prepared in Example 1 during the activation of PMS for BPA degradation. As can be seen from the figure, the presence of coexisting ions does not have a significant impact on the catalytic performance of CM, indicating that it has strong anti-interference ability.

[0052] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0053] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a nano-flower-like cobalt-molybdenum oxide catalytic material, characterized in that the steps include... include: Using cobalt salt, molybdenum salt and urea as reactants, a cobalt-molybdenum oxide precursor was obtained through a hydrothermal reaction. The cobalt-molybdenum oxide precursor was calcined to obtain the nano-flower-like cobalt-molybdenum oxide catalytic material. The cobalt salt includes CoSO4•7H2O; The molybdenum salt includes (NH4)6Mo7O 24 •4H2O.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the cobalt salt, molybdenum salt, and urea is (1.0~1.4):(0.6~1.0):(2.1~2.5).

3. The preparation method according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 120-140℃ for 8-10 hours.

4. The preparation method according to claim 1, characterized in that, The calcination process involves a heating rate of 2-5℃ / min, a temperature of 500-650℃, and a holding time of 3-4h.

5. The preparation method according to claim 1, characterized in that, The hydrothermal reaction also includes a purification step.

6. The preparation method according to claim 5, characterized in that, The impurity removal process involves rinsing with ethanol and water followed by vacuum drying.

7. A nano-flower-like cobalt-molybdenum oxide catalytic material, characterized in that, The nano-flower-like cobalt-molybdenum oxide catalytic material is prepared by the preparation method described in any one of claims 1-6.

8. The application of the nano-flower-like cobalt-molybdenum oxide catalytic material of claim 7 in the activation of persulfate.

9. The application of the nano-flower-like cobalt-molybdenum oxide catalytic material of claim 7 in the degradation of organic pollutants by activated persulfate.

10. A method for degrading bisphenol A in organic wastewater, characterized in that, The method uses the nano-flower-like cobalt-molybdenum oxide catalytic material described in claim 7 to activate persulfate to degrade bisphenol A in organic wastewater.

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