Preparation method of porous polyhedral Fe-Co bimetallic wastewater treatment catalyst

Abstract

The application discloses a preparation method of a porous polyhedral Fe-Co bimetallic wastewater treatment catalyst, relates to a preparation method of a water treatment catalyst, and discloses the following steps: firstly, dissolving a soluble Zn salt, a soluble Fe salt and a soluble Co salt in an alcohol solution to form a solution A by stirring; dissolving an imidazole derivative in an alcohol solution to form a solution B by stirring; then, mixing and stirring the A solution and the B solution and performing hydrothermal treatment; washing and drying the obtained solid with an alcohol solution to obtain an Fe-Co bimetallic MOF; and finally, preparing a porous polyhedral Fe-Co bimetallic catalyst rich in oxygen vacancies through high-temperature calcination. The catalyst has good degradation performance and stability for various refractory organic pollutants in wastewater under an activated PMS system.

Description

Technical Field

[0001] This invention relates to a method for preparing a catalyst, and more particularly to a method for preparing a porous polyhedral Fe-Co bimetallic wastewater treatment catalyst. Background Technology

[0002] Water is the source of life and the foundation of human survival and development. With industrial development, various pollutants are discharged into water bodies, posing a serious threat to human health. Therefore, the efficient removal of recalcitrant organic pollutants from water is an urgent problem to be solved. Currently, sulfate radical advanced oxidation technology is widely used in water treatment. This technology mainly utilizes various catalysts to activate persulfate, causing the O2O bonds to break and generate highly oxidizing reactive oxygen species such as sulfate radicals and hydroxyl radicals. These reactive oxygen species further react with organic pollutants, decomposing them and converting them into non-toxic intermediate products, water, and carbon dioxide. Catalysts are classified into homogeneous catalysts (transition metal ions, such as Fe2+, ... 2+ Co 2+ Cu 2 + Homogeneous catalysts are broadly classified into two categories: homogeneous catalysts (e.g., PMS) and heterogeneous catalysts (e.g., metal oxides, carbon-based materials). Homogeneous catalysts are prone to polluting water bodies, severely limiting their application in water pollution control. In heterogeneous catalysis, catalytic efficiency is affected by two main factors: the adsorption of PMS and pollutants on the catalyst surface, and the activation of PMS at the catalyst's active sites to generate reactive oxygen species (ROS). Therefore, preparing catalysts with abundant reactive sites and good adsorption capacity for PMS and pollutants is of great significance. Catalysts with single-metal active sites exhibit high metal leaching rates, low catalytic efficiency, and poor stability. Improving catalysts with bimetallic doping schemes can not only enrich active sites and promote the valence cycling of metal active sites, thereby enhancing the performance of active sites, but also the strong metallic bonds formed between the two metals can inhibit the leaching of metal ions. However, traditional nanoparticle catalysts have a small specific surface area, which is not conducive to the adsorption of pollutants and does not have a significant advantage in PMS adsorption. Theoretical calculations show that the presence of oxygen vacancies plays an important role in improving the adsorption of PMS by catalysts. Therefore, introducing oxygen vacancies into catalysts can enhance their adsorption capacity for PMS. Meanwhile, to improve the catalyst's adsorption capacity for pollutants, this invention designs a porous polyhedral structure. Metal-organic frameworks (MOFs) possess advantages such as high porosity, low density, large specific surface area, and regular pore structure, perfectly meeting the structural requirements of catalysts. Therefore, this invention uses a bimetallic MOF as a precursor to prepare a porous polyhedral bimetallic catalyst rich in oxygen vacancies for water environment remediation, addressing the problems existing in current similar catalysts. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing a porous polyhedral Fe-Co bimetallic catalyst for wastewater treatment. This method employs hydrothermal and high-temperature calcination to prepare a porous polyhedral Fe-Co bimetallic catalyst rich in oxygen vacancies. This catalyst preparation method is simple and can efficiently remove recalcitrant organic pollutants from water, achieving the goal of harmlessness and protecting the aquatic environment. Furthermore, this catalyst is easy to recover, exhibits low metal ion leaching, and possesses excellent catalytic activity and stability.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A method for preparing a porous polyhedral Fe-Co bimetallic wastewater treatment catalyst, the preparation steps of which are as follows:

[0006] Using MOF as a precursor, Fe and Co bimetals were introduced, and a porous polyhedral morphology was obtained by high-temperature calcination to introduce oxygen vacancies. Soluble Zn salt, soluble Fe salt, and soluble Co salt were used as precursors for the oxygen-vacancy-rich porous polyhedral Fe-Co bimetallic catalyst. First, 1-5 g of soluble Zn salt, 0.1-0.5 g of soluble Fe salt, and soluble Co salt were dissolved in 50-500 mL of alcohol solution and stirred for 10-90 min to form solution A. Then, 2-10 g of imidazole derivatives were dissolved in 50-200 mL of alcohol solution and stirred for 10-90 min to form solution B. Next, solutions A and B were mixed and stirred for 10-90 min. Finally, the solutions were transferred to a polytetrafluoroethylene autoclave and hydrothermally heated at 80-200℃ for 100-500 min. The resulting precipitate was washed with alcohol solution and vacuum dried at 60-100℃ for 6-10 minutes. h; thereby preparing a MOF doped with Fe and Co bimetals; then calcining the Fe and Co bimetals MOF in an air atmosphere at 300-700℃ for 1-4 h to introduce oxygen vacancies.

[0007] The method for preparing a porous polyhedral Fe-Co bimetallic catalyst for wastewater treatment describes a method for preparing a porous polyhedral Fe-Co bimetallic catalyst rich in oxygen vacancies. The catalyst has an 8-12-sided morphology with abundant pores and a mesoporous structure with a pore size of 20-50 nm. The contents of O, Fe, and Co in the catalyst are 10-20%, 0.3-1%, and 0.3-1%, respectively. The oxygen vacancy content is 30-50%. Fe and Co exist in divalent and trivalent states, respectively, with divalent Fe and Co accounting for 70-90% and 40-60%, respectively. Trivalent Fe and Co account for 10-30% and 40-60%, respectively.

[0008] The present invention discloses a method for preparing a porous polyhedral Fe-Co bimetallic catalyst for wastewater treatment. The wastewater treatment uses potassium persulfate (PMS) as the oxidant and tetracycline and rhodamine B as target pollutants, establishing a water treatment application system. The porous polyhedral Fe-Co bimetallic catalyst / PMS system rich in oxygen vacancies achieves 100% removal of rhodamine B at a concentration of 10-100 mg / L within 5 minutes; and 100% removal of tetracycline at a concentration of 10-50 mg / L within 20 minutes. In this catalytic system, free radical pathways (sulfate radicals, hydroxyl radicals), non-free radical pathways, and singlet oxygen all contribute to the removal of pollutants.

[0009] The advantages and effects of this invention are:

[0010] 1. This invention utilizes hydrothermal and high-temperature calcination methods to prepare a porous, polyhedral Fe-Co bimetallic catalyst rich in oxygen vacancies. This catalyst preparation method is simple and can efficiently remove recalcitrant organic pollutants from water, achieving the goal of harmlessness and protecting the aquatic environment. Furthermore, this catalyst is easy to recover, exhibits minimal metal ion leaching, and possesses excellent catalytic activity and stability.

[0011] 2. This invention solves the problems of few active sites, poor stability, high metal ion leaching rate and weak PMS adsorption in nanoparticle catalysts, and provides a method for preparing a porous polyhedral bimetallic catalyst rich in oxygen vacancies, which exhibits better catalytic performance and can efficiently remove recalcitrant organic pollutants in water. Attached Figure Description

[0012] Figure 1 SEM image of a porous polyhedral Fe-Co bimetallic catalyst rich in oxygen vacancies;

[0013] Figure 2 EPR image;

[0014] Figure 3 The graph shows the degradation effect of oxygen-vacancy-rich porous polyhedral Fe-Co bimetallic catalyst on Rhodamine B (RhB), tetracycline (TC), and methylene blue (MB).

[0015] Figure 4 The stability effect of the porous polyhedral Fe-Co bimetallic catalyst rich in oxygen vacancies is shown in the figure. Implementation

[0016] The outstanding features and significant advancements of the present invention are further illustrated below with reference to embodiments, which are intended to illustrate the invention but are not limited to the following examples.

[0017] Example 1: 1-5 g of soluble Zn salt, 0.1-0.5 g of soluble iron salt, and 0.05-0.2 g of soluble Co salt were dissolved in 50-500 mL of alcohol solution to form solution A. 2-10 g of imidazole derivatives were dissolved in 50-200 mL of alcohol solution to form solution B. Solutions A and B were then mixed thoroughly and transferred to a polytetrafluoroethylene autoclave for hydrothermal reaction.

[0018] Example 2: 1-5 g of soluble Zn salt, 0.1-0.5 g of soluble iron salt, and 0.02-0.05 g of soluble Co salt were dissolved in 50-500 mL of alcohol solution to form solution A. 2-10 g of imidazole derivatives were dissolved in 50-200 mL of alcohol solution to form solution B. Solutions A and B were then mixed thoroughly and transferred to a polytetrafluoroethylene autoclave for hydrothermal reaction.

[0019] Example 3: 1-5 g of soluble Zn salt, 0.02-0.07 g of soluble iron salt, and 0.05-0.2 g of soluble Co salt were dissolved in 50-500 mL of alcohol solution to form solution A. 2-10 g of imidazole derivatives were dissolved in 50-200 mL of alcohol solution to form solution B. Solutions A and B were then mixed thoroughly and transferred to a polytetrafluoroethylene autoclave for hydrothermal reaction.

[0020] Example 4: 0.5g of Fe and Co bimetallic MOF was calcined in a tube furnace at 300-700℃ for 1-4 h, with a heating rate of 2-10℃ / min.

[0021] Example 5: 0.5g of Fe and Co bimetallic MOF was calcined in a tube furnace at 200-600℃ for 1-4 h, with a heating rate of 2-10℃ / min.

[0022] Example 6: 0.01 g of a porous polyhedral Fe-Co bimetallic catalyst rich in oxygen vacancies was added to 100 mL of RhB, TC, and MB solutions, each with a concentration of 20 mg / L, and 80-200 μL of PMS (0.5 mol / L) was added to initiate the reaction. After the addition of PMS, 100% of RhB was removed within 5 min, 100% of MB within 10 min, and 100% of TC within 20 min.

Claims

1. A method for preparing a porous polyhedral Fe-Co bimetallic wastewater treatment catalyst, characterized in that, The preparation steps of the method are as follows: Using MOF as a precursor, Fe and Co bimetals were introduced, and a porous polyhedral morphology was obtained by high-temperature calcination while introducing oxygen vacancies. Soluble Zn salt, soluble Fe salt, and soluble Co salt were used as precursors for the porous polyhedral Fe-Co bimetallic catalyst rich in oxygen vacancies. First, 1-5 g of soluble Zn salt, 0.1-0.5 g of soluble Fe salt, and soluble Co salt were dissolved in 50-500 mL of alcohol solution and stirred for 10-90 min to form solution A. Then, 2-10 g of imidazole derivatives were dissolved in 50-200 mL of alcohol solution and stirred for 10-90 min to form solution B. Then mix solutions A and B and stir for 10-90 minutes; Finally, the solution was transferred to a polytetrafluoroethylene autoclave and hydrothermally heated at 80-200℃ for 100-500 min; the resulting precipitate was washed with an alcohol solution and vacuum dried at 60-100℃ for 6-10 h; Fe and Co bimetallic MOF was prepared in this way; the Fe and Co bimetallic MOF was then calcined in an air atmosphere at 300-700℃ for 1-4 h to introduce oxygen vacancies. The porous polyhedral Fe-Co bimetallic catalyst rich in oxygen vacancies exhibits a mesoporous structure with abundant pores, consisting of 8-12 hexahedrons and pore sizes of 20-50 nm. The catalyst contains 10-20% O, 0.3-1% Fe, and 0.3-1% Co, respectively. Oxygen vacancies account for 30-50% of the catalyst. Fe and Co exist in divalent and trivalent states, respectively, with divalent Fe and Co accounting for 70-90% and 40-60%, respectively, and trivalent Fe and Co accounting for 10-30% and 40-60%, respectively. The wastewater treatment uses potassium peroxymonosulfate as an oxidant and tetracycline and rhodamine B as target pollutants to establish a water treatment application system. In the catalytic system, both free radical and non-free radical pathways jointly lead to the removal of pollutants. The free radical pathway consists of sulfate radicals and hydroxyl radicals, while the non-free radical pathway is the singlet oxygen pathway.

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