Catalyst of solid solution of polymetallic phosphate, its preparation method and application

Abstract

The application discloses a kind of polymetallic phosphate solid solution catalyst and its preparation method and application, belong to environmental catalytic material field.The preparation method of the catalyst includes the following steps: first, nickel-based phosphate hollow porous nanomaterial is prepared as carrier material, and is dispersed in water to obtain suspension;Iron salt, cobalt salt, manganese salt and copper salt are dissolved in water to obtain mixed salt solution;Mixed salt solution and suspension are mixed uniformly, and polymetallic phosphate solid solution catalyst is prepared by ion exchange.The application introduces nickel and transition metals iron, cobalt, manganese and copper with different valence into catalyst system at the same time, utilizes the synergistic promotion effect generated by polymetal, significantly improves the catalytic performance of catalyst, can effectively catalyze Fenton reaction, realizes the efficient degradation of organic pollutants.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of environmental catalytic materials, and particularly relates to a multi-metal phosphate solid solution catalyst and a preparation method and application thereof. BACKGROUND

[0002] With the intensification of industrialization and agricultural activities, the residues and accumulation of organic pollutants, especially antibiotics and dyes, in water environment have become a serious environmental problem. The overuse and improper disposal of antibiotics, as well as the organic pollutants such as dyes generated in the industrial production process, not only pose a threat to the ecosystem, but also may affect human health through the food chain. Organic pollutants have poor biodegradability, and traditional treatment methods often have difficulty in effectively removing them, resulting in persistent pollution of water bodies and increasing antibiotic resistance.

[0003] In terms of antibiotic pollution, tetracycline antibiotics are particularly concerned due to their widespread use and difficulty in biodegradation. However, tetracycline is just one example of many organic pollutants, and others such as penicillins, cephalosporins, macrolide antibiotics, and various industrial dyes also cause serious pollution to the environment.

[0004] Currently, the degradation techniques for these organic pollutants mainly include biological degradation, chemical degradation, and physical degradation, etc. However, these methods generally have low treatment efficiency, high cost, and secondary pollution problems. In addition, the existing catalyst preparation methods often have complex steps, high cost, and unstable catalytic efficiency, which limits their popularization in practical applications.

[0005] To address this challenge, researchers have been seeking and developing new and efficient catalysts and catalytic methods to improve the degradation efficiency of organic pollutants and reduce the treatment cost. Metal-based catalysts show great application potential in the field of organic pollutant degradation due to their unique electronic structure and catalytic activity. SUMMARY

[0006] To address the problems existing in the prior art, the present application provides a multi-metal phosphate solid solution catalyst and a preparation method and application thereof. By introducing nickel and transition metals of different valence states, such as iron, cobalt, manganese, and copper, into the catalyst system simultaneously, the present application utilizes the synergistic promotion effect of multiple metals to significantly improve the catalytic performance of the catalyst, which can effectively catalyze the Fenton reaction and achieve the degradation of organic pollutants. The present application mainly includes the following aspects:

[0007] The first aspect of the present application is to provide a preparation method of a multi-metal phosphate solid solution catalyst, comprising the following steps:

[0008] Preparation of a phosphate precursor solution and a nickel salt solution, respectively, the nickel salt solution is added to the phosphate precursor solution, and the reaction is carried out under stirring, and after low-temperature aging, a nickel-based phosphate hollow porous nanomaterial is obtained; preferably, the phosphate used for preparing the phosphate precursor solution is at least one of disodium hydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, potassium phosphate, and sodium phosphate; the nickel salt used for preparing the nickel salt solution is at least one of nickel sulfate, nickel chloride, and nickel nitrate;

[0009] The iron salt, the cobalt salt, the manganese salt, and the copper salt are dissolved in water to obtain a mixed salt solution; the nickel-based phosphate hollow porous nanomaterial is dispersed in water to obtain a suspension; the mixed salt solution and the suspension are mixed uniformly, and a multi-metal phosphate solid solution catalyst is prepared through ion exchange. Preferably, the iron salt, the cobalt salt, the manganese salt, and the copper salt are each independently selected from a chloride salt, a nitrate salt, a sulfate salt, or an organometallic salt of a metal; the molar ratio of iron: cobalt: manganese: copper in the mixed salt solution is (30-45):(15-25):(10-20):(5-15).

[0010] The second aspect of the present application is to provide the multi-metal phosphate solid solution catalyst prepared by the preparation method of the first aspect, wherein the total metal loading of the multi-metal phosphate solid solution catalyst is 8-12 wt%, and the metal loading is too low to have insufficient active site density, or too high to damage the original structure of the carrier and thus cause the specific surface area to decrease. The catalyst introduces nickel and transition metals iron, cobalt, manganese, and copper into the catalyst system at the same time, utilizes the synergistic promotion effect of nickel and transition metals iron, cobalt, manganese, and copper, significantly improves the catalytic performance of the catalyst, and can effectively catalyze the Fenton reaction to achieve degradation of organic pollutants.

[0011] The third aspect of the present application is to provide the application of the multi-metal phosphate solid solution catalyst in degradation of organic pollutants in water, which comprises the following steps: adding the multi-metal phosphate solid solution catalyst and an oxidizing agent to water containing organic pollutants, and degrading the organic pollutants through the Fenton reaction. As a preferred technical solution, the oxidizing agent is a peroxymonosulfate; the pollutants include antibiotics and dyes. Further, the antibiotics are tetracycline antibiotics, penicillin antibiotics, cephalosporin antibiotics, or macrolide antibiotics.

[0012] The present application has the following beneficial effects:

[0013] The introduction of multiple metals in the catalyst prepared by the present application helps to improve the activity and stability of the catalyst. Specifically, the introduction of iron / cobalt metals is beneficial to the generation of dominant free radicals, and cobalt can maintain high activity under alkaline conditions (Co 2 + / Co 3+Low conversion barrier of valence state, solve the pH limitation of iron-based catalyst; manganese provides Mn 2+ / Mn 3+ / Mn 4+ Multi-valence, promote the continuous generation of free radicals; due to Cu + / Cu 2+ High reduction potential of the electric pair, copper can accelerate Fe 3+ →Fe 2+ Reduction step. In addition, the solid solution catalyst prepared by the application selects nickel-based phosphate as the carrier material, which has high stability (acid and alkali resistance) and controllable magnetism (easy recovery), solving the separation problem of nanometer catalyst. The cascade function of four metals is integrated in the nickel-based phosphate carrier, breaking through the bottleneck of traditional catalysts that are difficult to achieve "activity-stability-suitability".

[0014] The raw materials used in the application are cheap and easy to obtain, the operation method is simple, and the synthesis is convenient. The prepared multi-metal phosphate solid solution catalyst can be applied to heterogeneous Fenton-like oxidation reaction, and can efficiently degrade organic pollutants. Since the catalyst is simple to prepare and easy to industrialize, it has high degradation efficiency for pollutants and high application value in organic pollutant wastewater treatment, and has good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 SEM image of the iron-cobalt-nickel-manganese-copper multi-metal phosphate solid solution catalyst prepared in Example 1;

[0016] Figure 2 FT-IR spectrum of the iron-cobalt-nickel-manganese-copper multi-metal phosphate solid solution catalyst prepared in Example 1;

[0017] Figure 3 XRD diffraction pattern of the nickel-based phosphate hollow porous nanomaterial prepared in Example 1 and Comparative Example 1;

[0018] Figure 4 Effect diagram of the catalyst prepared in different examples and comparative examples on the degradation of tetracycline. DETAILED DESCRIPTION

[0019] The application will be further described below in conjunction with specific examples, but the essential content of the application is not limited to the examples described below. The methods are conventional methods unless otherwise specified, and the materials can be obtained from public commercial channels unless otherwise specified. Those skilled in the art should know that any simple transformation or substitution based on the essential content of the application is within the scope of protection required by the application.

[0020] Example 1

[0021] A preparation method of an iron-cobalt-nickel-manganese-copper multi-metal phosphate solid solution catalyst, comprising the following steps:

[0022] Step 1: Dissolve 21.6 mg of potassium dihydrogen phosphate, 163 mg of dipotassium hydrogen phosphate, 711 mg of sodium chloride and 18 mg of potassium chloride in 90 mL of water solution to prepare a phosphate precursor solution; dissolve 315.4 mg of nickel phosphate hexahydrate in 4 mL of ultrapure water to prepare a nickel salt solution with a concentration of 0.3 mol / L;

[0023] Step 2: Add the nickel sulfate solution dropwise to the phosphate precursor solution and stir well to ensure that the nickel ions and phosphate ions are fully mixed;

[0024] Step 3: Cool the reaction system to -4°C in the refrigerator and age at low temperature for 12 hours to promote the formation of nickel-based phosphate hollow porous nanostructures;

[0025] Step 4: Centrifuge to collect the precipitate, wash the precipitate with ultrapure water to remove unreacted raw materials and byproducts, and dry at 70°C under vacuum conditions to obtain a nickel-based phosphate hollow porous nanomaterial;

[0026] Step 5: Add 100 mg of the washed and dried nickel-based phosphate hollow porous nanomaterial to 80 mL of ultrapure water to obtain a suspension; add 27.8 mg of iron sulfate heptahydrate, 28.1 mg of cobalt sulfate heptahydrate, 24.1 mg of manganese sulfate monohydrate, and 24.95 mg of copper sulfate pentahydrate to 20 mL of ultrapure water to obtain a mixed salt solution; add the mixed salt solution to the suspension and stir well for 12 hours to prepare a multi-metal phosphate solid solution catalyst by ion exchange;

[0027] Step 6: Centrifuge to collect the precipitate, wash the precipitate with ultrapure water to remove unreacted raw materials, and dry at 70°C under vacuum conditions to obtain a multi-metal phosphate solid solution catalyst material;

[0028] Figure 1 SEM and mapping images of the iron-cobalt-nickel-manganese-copper multi-metal phosphate solid solution catalyst prepared in Example 1, where A is the SEM image and B is the mapping image, from Figure 1 it can be seen that the iron-cobalt-nickel-manganese-copper multi-metal phosphate solid solution catalyst is flocculent and flaky, and the structure of the product has changed greatly compared to the carrier nickel-based phosphate hollow porous nanomaterial. The reason is that due to the introduction of Fe 3+ , Co 2+ , Mn 2+ , Cu 2+ and other high-valence metal ions for ion exchange, a quaternary solid solution system is formed, and this multi-metal synergistic effect breaks the single metal doping mode. The ionic radius of Co 2+ , Mn 2+ is significantly larger than Ni2+ , resulting in the lattice expansion in the c-axis direction, forcing the system to release the strain energy by two-dimensional epitaxial growth. Therefore, the final product of the present application presents a flocculent sheet structure with the coexistence of residual hollow sphere fragments and newly born nanosheets. The present application breaks through the dependence of traditional single / dual metal doping on the spherical structure of the carrier by lattice engineering triggered by multi-metal synergistic doping, and realizes the controllable transition from the thermodynamic stable state to the kinetic metastable state. This morphology reconstruction is essentially a reselection of the free energy minimization path of crystal growth, rather than a simple physical crushing process. This discovery provides a new design concept for developing high-performance catalysts - by artificially introducing a non-equilibrium stress field to directionally control the surface and interface characteristics of the material.

[0029] Figure 2 FT-IR spectrum of the iron-cobalt-nickel-manganese-copper multi-metal phosphate solid solution catalyst prepared in Example 1. The basic framework structure of the iron-cobalt-nickel-manganese-copper multi-metal phosphate solid solution catalyst of the present application can be proved from the FT-IR spectrum.

[0030] Figure 3 XRD diffractogram of the iron-cobalt-nickel-manganese-copper multi-metal phosphate solid solution catalyst prepared in Example 1 and the nickel-based phosphate prepared in Comparative Example 1. The iron-cobalt-nickel-manganese-copper multi-metal phosphate catalyst of the present application maintains a consistent crystal phase structure with the precursor nickel-based phosphate, as can be seen from the XRD diffractogram, so the catalyst is a solid solution catalyst. The possible reason is that the metal ions enter the lattice gap or occupy a specific position without changing the overall structure, which may lead to the main phase unchanged. It is also possible that the formed solid solution belongs to the same space group, only the lattice parameters are slightly adjusted, which is difficult to detect in conventional XRD.

[0031] Application Example

[0032] The iron-cobalt-nickel-manganese-copper multi-metal phosphate solid solution catalyst obtained in this example was applied to the degradation of tetracycline in water: 5 mg of the iron-cobalt-nickel-manganese-copper multi-metal phosphate solid solution catalyst prepared in Example 1 was added to 50 mL of tetracycline solution with a concentration of 20 mg·L -1 , 1 mM PMS was added, and the mixture was shaken at 25°C and sampled every 20 minutes for detection of the residual content of tetracycline in the aqueous solution. The concentration defined as the measured concentration was detected, and the initial concentration was 20 mg·L -1 , then the removal rate = measured concentration / initial concentration.

[0033] Figure 4 The results of the degradation of tetracycline by the catalysts prepared in different examples and comparative examples in the presence of PMS are shown in Table 1, from which it can be seen that the iron-cobalt-nickel-manganese-copper multi-metal phosphate solid solution catalyst of the present application has the best catalytic effect. Figure 4As can be seen from Table 1, the removal rate of tetracycline by the catalyst prepared in Example 1 is 98.7% when the reaction time is 20 min. If only 1 mM PMS is added without the catalyst of the present application (marked as blank group), the removal rate is only 18.8% within 20 min.

[0034] Comparative Example 1

[0035] The difference between the present comparative example and Example 1 is that only step 1 in Example 1 is performed, and the process is the same as that in Example 1; the prepared catalyst is recorded as nickel-based hollow porous phosphonate nanomaterial.

[0036] The catalyst obtained in the present comparative example is applied to the degradation of tetracycline in water: 5 mg of the catalyst prepared in the present comparative example is added to 50 mL of water sample with a tetracycline concentration of 20 mg·L-1, 1 mM PMS is added, and the sample is fully shaken in a shaking table at 25°C, and the residual content of tetracycline in the aqueous solution is detected by sampling and filtering at 20 min. -1 As can be seen from Table 1, the removal rate of tetracycline by the catalyst prepared in Example 1 is 98.7% when the reaction time is 20 min. If only 1 mM PMS is added without the catalyst of the present application (marked as blank group), the removal rate is only 18.8% within 20 min. Figure 4

[0037] Comparative Example 2

[0038] The difference between the present example and Example 1 is that 27.8 mg of iron sulfate heptahydrate, 28.1 mg of cobalt sulfate heptahydrate, 24.1 mg of manganese sulfate monohydrate, and 24.95 mg of copper sulfate pentahydrate in step 1 are replaced by 99.8 mg of copper sulfate pentahydrate, and the other processes are the same as those in Example 1; the prepared catalyst is recorded as copper-nickel bimetallic phosphonate catalyst.

[0039] The catalyst obtained in the present comparative example is applied to the degradation of tetracycline in water: 5 mg of the catalyst prepared in the present comparative example is added to 50 mL of water sample with a tetracycline concentration of 20 mg·L-1, 1 mM PMS is added, and the sample is fully shaken in a shaking table at 25°C, and the residual content of tetracycline in the aqueous solution is detected by sampling and filtering at 20 min. -1 As can be seen from Table 1, the removal rate of tetracycline by the catalyst prepared in Example 1 is 98.7% when the reaction time is 20 min. If only 1 mM PMS is added without the catalyst of the present application (marked as blank group), the removal rate is only 18.8% within 20 min. Figure 4

[0040] Comparative Example 3

[0041] The difference between the present example and Example 1 is that 27.8 mg of iron sulfate heptahydrate, 28.1 mg of cobalt sulfate heptahydrate, 24.1 mg of manganese sulfate monohydrate, and 24.95 mg of copper sulfate pentahydrate in step 1 are replaced by 111.2 mg of iron sulfate heptahydrate, and the other processes are the same as those in Example 1; the prepared catalyst is recorded as iron-nickel bimetallic phosphonate catalyst. ​​

[0042] The catalyst obtained in the present comparative example was applied to the degradation of tetracycline in water: 5 mg of the catalyst prepared in the present comparative example was added to 50 mL of water sample with a tetracycline concentration of 20 mg·L-1, 1 mM PMS was added, and the mixture was fully shaken in a shaking table at 25℃. The residual content of tetracycline in the aqueous solution was detected by sampling and filtering at 20 min. It can be seen from Table 1 that, when the reaction time was 20 min, the removal rate of tetracycline by the catalyst prepared in Comparative Example 3 was 46.2%. -1 Figure 4

[0043] Comparative Example 4

[0044] Compared with Example 1, the difference of the present example lies in that 27.8 mg of iron sulfate heptahydrate, 28.1 mg of cobalt sulfate heptahydrate, 24.1 mg of manganese sulfate monohydrate, and 24.95 mg of copper sulfate pentahydrate in Step 1 were replaced by 48.2 mg of manganese sulfate monohydrate, and the other processes were the same as those in Example 1. The prepared catalyst was recorded as a manganese-nickel bimetallic phosphate catalyst.

[0045] The catalyst obtained in the present comparative example was applied to the degradation of tetracycline in water: 5 mg of the catalyst prepared in the present comparative example was added to 50 mL of water sample with a tetracycline concentration of 20 mg·L-1, 1 mM PMS was added, and the mixture was fully shaken in a shaking table at 25℃. The residual content of tetracycline in the aqueous solution was detected by sampling and filtering at 20 min. It can be seen from Table 1 that, when the reaction time was 20 min, the removal rate of tetracycline by the catalyst prepared in Comparative Example 3 was 46.2%. -1 Figure 4

[0046] From the experimental results of the above examples and comparative examples, it can be seen that, compared with the products prepared by ion exchange of single metal salt such as manganese, iron, copper, and nickel-based phosphate, the catalyst prepared by the combined action of multiple metal ions in the examples has better catalytic performance and can significantly improve the catalytic efficiency of the catalyst.

[0047] It should be noted that, in other examples, when the experimental process meets the following conditions, the purpose of the present application can be achieved. Obviously, the described examples are part of the examples of the present application, not all examples. Based on the examples in the present application, all other examples obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.​​​​

Claims

1. A method for preparing a poly-metaphosphate solid solution catalyst for Fenton reaction, characterized in that, The preparation method comprises the following steps: Preparation of a phosphate precursor solution and a nickel salt solution, respectively, addition of the nickel salt solution to the phosphate precursor solution, reaction under stirring, and aging at low temperature to obtain a nickel-based phosphate hollow porous nanomaterial; Dissolution of iron salt, cobalt salt, manganese salt and copper salt in water to obtain a mixed salt solution; dispersion of the nickel-based phosphate hollow porous nanomaterial in water to obtain a suspension; mixing of the mixed salt solution and the suspension uniformly, and preparation of a multi-metal phosphate solid solution catalyst through ion exchange; The total metal loading of the multi-metal phosphate solid solution catalyst is 8-12 wt%.

2. The production method according to claim 1, characterized by, The phosphate used for preparation of the phosphate precursor solution is at least one of disodium hydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, potassium phosphate and sodium phosphate.

3. The production method according to claim 1, characterized by, The nickel salt used for preparation of the nickel salt solution is at least one of nickel sulfate, nickel chloride and nickel nitrate.

4. The method of claim 1, wherein, The iron salt, cobalt salt, manganese salt and copper salt are each independently selected from chloride, nitrate or sulfate of a metal or an organic metal salt.

5. The multi-metal phosphate solid solution catalyst for Fenton reaction prepared by the preparation method according to any one of claims 1 to 4.

6. Use of the poly-metaphosphate solid solution catalyst for Fenton reaction according to claim 5 for degrading organic pollutants in water, characterized in that, The method comprises the following steps: addition of the multi-metal phosphate solid solution catalyst and an oxidant to a water body containing organic pollutants, and degradation of the organic pollutants through Fenton reaction.

7. Use of the multi-metal phosphates solid solution catalyst for Fenton reaction according to claim 6, characterized in that, The oxidant is peroxymonosulfate.

8. Use of the multi-metal phosphates solid solution catalyst for Fenton reaction according to claim 6 for degrading organic pollutants in water, characterized in that, The organic pollutants include antibiotics and dyes.

9. Use of the multi-metal phosphates solid solution catalyst for Fenton reaction according to claim 8, characterized in that, The antibiotics are tetracycline antibiotics, penicillin antibiotics, cephalosporin antibiotics or macrolide antibiotics. The method comprises the following steps: addition of the multi-metal phosphate solid solution catalyst and an oxidant to a water body containing organic pollutants, and degradation of the organic pollutants through Fenton reaction. The oxidant is peroxymonosulfate. The organic pollutants include antibiotics and dyes. The antibiotics are tetracycline antibiotics, penicillin antibiotics, cephalosporin antibiotics or macrolide antibiotics.

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