FeSe2 / CoSe2 catalyst as well as preparation method and application thereof

Abstract

The invention provides a FeSe2 / CoSe2 catalyst as well as a preparation method and application thereof, and belongs to the technical field of photocatalytic degradation. According to the invention, FeSe2 and CoSe2 are respectively prepared through a solvothermal method, a FeSe2 / CoSe2 catalyst is successfully prepared through a hydrothermal method, and metronidazole (MNZ) is selected to inspect the catalytic effect of the catalyst in the PMS activation degradation process. After the FeSe2 / CoSe2 / PMS system is irradiated by visible light for 20 minutes, the excellent degradation efficiency of the FeSe2 / CoSe2 / PMS system on MNZ is 99%, which shows that the catalyst has excellent activation capability on PMS.

Description

Technical Field

[0001] The invention relates to the technical field of photocatalytic degradation, and in particular to a FeSe2 / CoSe2 catalyst and a preparation method and application thereof. Background Art

[0002] Pharmaceuticals and personal care products (PPCPs) are a class of drugs (such as antibiotics and analgesics) and personal care products (such as cosmetics, disinfectants and shampoos) used to prevent or treat human and poultry diseases. Metronidazole (MNZ) is a nitroimidazole antibiotic widely used to treat skin infections, anaerobic and parasitic infections and as a hyperpolarized (HP) contrast agent to test drug delivery or perform cancer screening. After extensive use, traces of their harmful products in different forms have been detected in aquatic environments such as groundwater, fresh water and drinking water. Therefore, based on its high water solubility (9.5 g / dm 3 ), non-biodegradability, neurotoxicity, and potential carcinogenicity and mutagenicity, they have received increasing attention as emerging pollutants in the field of environmental governance. However, residual harmful substances often accumulate in microorganisms or animals in water bodies and are transmitted through the food chain, thus seriously threatening the quality of human life. Therefore, in order to meet people's demand for water resources, it is urgent to find a method to efficiently eliminate MNZ from water pollution.

[0003] Advanced oxidation processes (AOPs) are one of the important methods to achieve effective mineralization of organic pollutants and have become a hot topic in the field of water treatment. - ) or empty hole (h + ) undergoes redox reactions to generate highly reactive oxygen species (ROS) such as sulfate radicals (SO4 ·- ) and singlet oxygen ( 1 O2), etc. The generation of active groups determines its important role in removing some harmful pollutants, transforming and reducing biological toxicity. PMS can be activated to generate active species by light activation, multiphase activation, heating and alkali, but these methods are limited by high costs and high equipment requirements. In the past few decades, transition metal (TM) catalysts have been used in the field of catalysis in the form of ions or complexes, and provide another option for the generation of free radicals. Compared with other PMS activation methods, those based on transition metal-based materials, such as Mn 2+ / Mn 3+ / Mn 4+ , Fe 2+ / Fe 3+ and Co 2+ / Co 3+Due to its high redox potential, it is considered the most convenient and economical activator, playing a leading role in the redox process. However, although a single catalyst can achieve the ideal PMS activation efficiency, there are risks such as huge catalyst consumption loss, insufficient reuse and secondary pollution.

[0004] Selenium (Se) has low electronegativity and high conductivity compared to oxygen (O) and sulfur (S) in the same main group, which makes it easier to control the electronic structure of selenides and their bonding with metal ions, thus making the electrochemical reaction more active. In addition, it also has thermal stability, redox properties and mechanical stability. Due to these advantages, selenides should have better electrochemical properties than oxides and sulfides. On the one hand, various transition metal oxides (TMOs) and transition metal hydroxides (TMOHs), such as manganese oxide, cobalt oxide and cobalt / nickel hydroxide, have been successfully prepared. On the other hand, a lot of research work has been focused on developing the full potential of transition metal selenides and optimizing their properties, and a variety of selenides have been successfully prepared, such as Anand, TJS et al. prepared microcrystalline NiSe2. Zhang, J. et al. synthesized layered MoSe2 nanotubes for the first time. The nanotubes have layered organization, hollow interior and interlayer expansion, which are conducive to adapting to the volume change after adsorption / deoxidation and maintaining structural and morphological stability. In addition, non-layered selenides such as CoSe2, FeSe2, and CuSe2 show a three-dimensional crystal structure, which causes anisotropic electron transfer on specific crystal planes, thereby promoting the occurrence of adsorption / desorption reactions.

[0005] FeSe2 is a kind of material with extremely high absorption coefficient (>10 5 cm -1) semiconductor material with a band gap of about 1eV, which belongs to a narrow band gap and is commonly used in batteries, supercapacitors and photocatalysts. Due to these characteristics, iron selenide should have better photoelectrochemical performance than iron oxide and iron sulfide. CoSe2 is a relatively stable transition metal selenide with a simple synthesis method and a narrow band gap (1.78eV). When it is in the ground state, it is an exchange-enhanced paramagnetic metal and exhibits a local magnetic moment at high temperature. In addition, it has a good cobalt ion electronic configuration. Compared with FeSe2, it has a tunable band gap and can be used as a co-catalyst on the surface of FeSe2 to improve the photoelectrochemical (PEC) performance. Studies have shown that the deposition of most co-catalysts helps to increase the interfacial charge transfer rate, inhibit photocorrosion, and improve the stability of the catalyst. However, in actual research, pure CoSe2 catalysts can provide fewer reactive active sites, resulting in a catalytic effect that cannot meet actual needs. However, researchers currently pay less attention to the application of transition metal selenides in photocatalytic degradation of organic pollutants, and its degradation mechanism needs to be further elucidated. Heterostructures can produce a large number of lattice defects and distortions in non-uniform interfaces. These high-energy interfaces have unique electronic conversion modes, which will further expand the specific surface area and obtain more active sites. Therefore, designing heterostructure catalysts is also a promising strategy. Summary of the invention

[0006] The object of the present invention is to provide a FeSe2 / CoSe2 catalyst and a preparation method and application thereof, so as to solve the above technical problems.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing a FeSe2 / CoSe2 catalyst, comprising the following steps:

[0009] (1) mixing a ferrous chloride solution and a selenium solution and performing a solvothermal reaction, and drying the product to obtain FeSe2;

[0010] (2) After CoSe2 is dispersed in water, FeSe2 is added and ultrasonically mixed, followed by a hydrothermal reaction. After the product is dried, a FeSe2 / CoSe2 catalyst is obtained.

[0011] Furthermore, the temperature of the solvent thermal reaction is 150-170° C., and the reaction time is 10-14 hours.

[0012] Furthermore, the temperature of the hydrothermal reaction is 170-190° C., and the reaction time is 8-12 hours.

[0013] Furthermore, the ferrous chloride solution is obtained by dissolving FeCl2·4H2O in ethanolamine, and the mass concentration of the ferrous chloride solution is 30-50 g / L.

[0014] Furthermore, the selenium solution is obtained by dissolving Se powder in ethanolamine, and the mass concentration of the selenium solution is 13-15 g / L.

[0015] Furthermore, in step (1), the drying temperature is 50 to 70° C., and the drying time is 10 to 14 hours.

[0016] Furthermore, the mass ratio of CoSe2 to FeSe2 is 40-80 mg:0.1 g, the dosage ratio of CoSe2 to water is 40-80 mg:60 mL; and the ultrasonic mixing time is 3-5 min.

[0017] Furthermore, in step (2), the drying temperature is 50 to 70° C., and the drying time is 10 to 14 hours.

[0018] The invention also provides a FeSe2 / CoSe2 catalyst.

[0019] The present invention also provides an application of a FeSe2 / CoSe2 catalyst in activating peroxymonosulfate to degrade metronidazole.

[0020] Beneficial effects of the present invention:

[0021] The present invention synthesizes the FeSe2 / CoSe2 composite catalyst and uses it for PMS oxidation to degrade metronidazole in water, which has the following advantages:

[0022] (1) The diamond-shaped FeSe2 and the flake-shaped CoSe2 were hydrothermally synthesized to form a compact FeSe2 / CoSe2 composite catalyst.

[0023] (2) The excellent degradation efficiency of MNZ by FeSe2 / CoSe2 / PMS system after 20 min of visible light irradiation is 99%, indicating that the catalyst has excellent activation ability for PMS and can maintain effective degradation and metal leaching inhibition in a wide pH range. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The FESEM image, EDX image, pore size distribution and N2 adsorption-desorption isotherm of the catalyst prepared in Example 3 of the present invention;

[0025] Figure 2 HRTEM image of the catalyst prepared in Example 3 of the present invention;

[0026] Figure 3XRD diagram and Raman spectrum diagram of the catalyst prepared by the present invention;

[0027] Figure 4 The XPS full spectrum scan diagram of Example 3 and the UV-Vis DRS diagrams of Examples 1 to 3;

[0028] Figure 5 The photocatalytic degradation of MNZ by the catalyst prepared in Example 3 (a), -ln (C t / C0) as a function of reaction time during degradation (b), CoSe2 doping amount (c) and first-order kinetics (d);

[0029] Figure 6 It is a curve diagram showing the effect of different conditions (pH value, PMS amount, catalyst usage and MNZ concentration) on the catalyst in the process of MNZ degradation;

[0030] Figure 7 (a) Different water qualities; (b) Different pollutants; (c) Cycle experiment; (d) Effect of common anions on the degradation performance of MNZ. DETAILED DESCRIPTION

[0031] The present invention provides a method for preparing a FeSe2 / CoSe2 catalyst, comprising the following steps:

[0032] (1) mixing a ferrous chloride solution and a selenium solution and performing a solvothermal reaction, and drying the product to obtain FeSe2;

[0033] (2) After CoSe2 is dispersed in water, FeSe2 is added and ultrasonically mixed, followed by a hydrothermal reaction. After the product is dried, a FeSe2 / CoSe2 catalyst is obtained.

[0034] In the present invention, the temperature of the solvent thermal reaction is 150-170° C., preferably 160° C.; the reaction time is 10-14 h, preferably 12 h.

[0035] In the present invention, the temperature of the hydrothermal reaction is 170-190° C., preferably 180° C.; the reaction time is 8-12 h, preferably 10 h.

[0036] In the present invention, the preparation method of CoSe2 comprises the following steps:

[0037] Se powder is dissolved in a mixed solution of sodium hydroxide and water to obtain solution A; cobalt chloride is dissolved in a mixed solution of disodium ethylenediaminetetraacetate and water to obtain solution B; solution A and solution B are mixed and subjected to a solvothermal reaction, and the product is dried to obtain CoSe2;

[0038] In the present invention, the usage ratio of the Se powder, sodium hydroxide and water is 0.3-0.5g:2.4g:60mL, preferably 0.32g:2.4g:60mL; the usage ratio of the cobalt chloride, disodium ethylenediaminetetraacetate and water is 0.4-0.5g:0.7-0.8g:20mL, preferably 0.48g:0.73g:20mL; the temperature of the solvent thermal reaction is 170-190°C, preferably 180°C; the reaction time is 10-14h, preferably 12h.

[0039] In the present invention, the ferrous chloride solution is obtained by dissolving FeCl2·4H2O in ethanolamine, and the mass concentration of the ferrous chloride solution is 30-50 g / L, preferably 33-45 g / L, and more preferably 35-40 g / L.

[0040] In the present invention, the selenium solution is obtained by dissolving Se powder in ethanolamine, and the mass concentration of the selenium solution is 13-15 g / L, preferably 13.5-14.5 g / L, and more preferably 14 g / L.

[0041] In the present invention, in the step (1), the drying temperature is 50-70° C., preferably 60° C.; the drying time is 10-14 h, preferably 12 h.

[0042] In the present invention, the mass ratio of CoSe2 and FeSe2 is 40-80 mg:0.1 g, preferably 60 mg:0.1 g or 80 mg:0.1 g; the dosage ratio of CoSe2 and water is 40-80 mg:60 mL, preferably 60 mg:60 mL; the ultrasonic mixing time is 3-5 min, preferably 3 min, 4 min, 5 min.

[0043] In the present invention, in the step (2), the drying temperature is 50-70° C., preferably 60° C.; the drying time is 10-14 h, preferably 12 h.

[0044] The invention also provides a FeSe2 / CoSe2 catalyst.

[0045] The present invention also provides an application of a FeSe2 / CoSe2 catalyst in activating peroxymonosulfate to degrade metronidazole.

[0046] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0047] Example 1

[0048] (1) Preparation of CoSe2

[0049] First, 2.40g NaOH was added to 60mL ultrapure water and stirred evenly, followed by the addition of 0.32g Se powder, followed by magnetic stirring for 15min to form solution A; secondly, 0.48g CoCl2·6H2O and 0.73g EDTA-2Na were added to 20mL ultrapure water and stirred for 10min to form solution B. Subsequently, solution B was poured into solution A and mixed, stirred for 5min, and the mixed solution was ultrasonicated for 30min and stirred for another 10min to obtain a uniform solution. The mixed solution was poured into a 100mL polytetrafluoroethylene reactor and heated at 180℃ for 12h. The obtained product was then centrifuged, washed with ultrapure water 3 times, and dried at 60℃ for 12h to obtain CoSe2 for later use.

[0050] (2) Preparation of FeSe2

[0051] First, 1.0 g of FeCl2·4H2O was added to 30 mL of ethanolamine and then stirred for 30 minutes, which was called solution A. In addition, 0.4 g of Se powder was added to 30 mL of ethanolamine and stirred for 30 minutes to obtain solution B. Then, solution B was poured into solution A under magnetic stirring. After stirring for 30 minutes, the mixed solution was transferred to a 100 mL polytetrafluoroethylene autoclave and reacted at 160°C for 12 hours. Finally, the material was centrifuged, washed 3 times with deionized water and 2 times with anhydrous ethanol, and dried at 60°C for 12 hours.

[0052] (3) Add 40 mg CoSe2 to 60 mL ultrapure water, stir for 5 minutes, and then sonicate for 3 minutes to form a black uniform liquid. Subsequently, add 0.10 g FeSe2, stir for 5 minutes, sonicate for 3 minutes to dissolve, continue stirring for 1 hour, and then pour into 100 mL polytetrafluoroethylene reaction axe and hydrothermally react at 180°C for 10 hours. Finally, the obtained black product was centrifuged at high speed, washed with ultrapure water 4 times, and dried at 60°C for 10 hours to obtain the FeSe2 / CoSe2 catalyst, named FC40.

[0053] Example 2

[0054] Same as Example 1, except that the amount of CoSe2 used is 60 mg. The obtained FeSe2 / CoSe2 catalyst is named FC60.

[0055] Example 3

[0056] The same as Example 1, except that the amount of CoSe2 used is 80 mg. The obtained FeSe2 / CoSe2 catalyst is named FC80.

[0057] The performance of the above catalysts FC40, FC60 and FC80 was characterized:

[0058] Catalytic performance:

[0059] 20 mg of FeSe2 / CoSe2 catalyst was added to the MNZ solution, stirred in the dark for 30 min to reach adsorption-desorption equilibrium, and then a certain amount of PMS (2 mM) was added and a metal halide lamp with a 420 nm cutoff filter was turned on at the same time. During the catalytic process, 3 mL of the solution was taken at a given time interval and the catalyst was filtered through a 0.22 μm microporous membrane. The concentration of residual MNZ was determined by UV-visible spectrophotometry (λ = 320 nm).

[0060] The FESEM images show the microscopic morphology of FeSe2, CoSe2 and FC80 samples. Figure 1 As shown in a and 1b, FeSe2 is in an irregular rhombus shape and there are no other impurities on the surface. Figure 1 c and 1d show that CoSe2 particles form a lamellar structure at high temperature, and it can be found that there are many CoSe2 particles on its surface. Figure 1 e and 1f show that after FeSe2 and CoSe2 self-assemble through hydrothermal reaction, the rhombic FeSe2 and the flake CoSe2 form a tight heterojunction interface, and the combination of the two transition metal selenides effectively provides interfacial charge transfer efficiency.

[0061] HRTEM further characterized the morphology of FC80 and found that there was an obvious inter-plane distribution between the catalysts, such as Figure 2 As shown in ac, it can be clearly found that CoSe2 and FeSe2 are tightly combined with each other.

[0062] XRD analysis is very important for analyzing the phase of a substance and is also one of the most common methods. Figure 3 a and 3b. Figure 3The standard cards and XRD patterns of different materials are shown in a. It can be observed in detail that the main peak of FeSe2 in the XRD phase structure mode is consistent with the diffraction peak of the standard card (PDF#74-0247). Therefore, the main characteristic diffraction peaks at 23.6°, 29.7°, 31.2°, 34.9°, 36.3°, 41.5°, 48.2°, 51.0° and 54.0° correspond to the (011), (101), (110), (111), (012), (021), (121), (200) and (103) crystal planes in the FeSe2 standard card, indicating that the prepared material has a high crystal phase purity. The main peak of CoSe2 material in the XRD phase structure mode corresponds to the diffraction peak of the standard card (PDF#89-2003). Therefore, the main characteristic diffraction peaks at 23.7°, 29.6°, 30.7°, 34.4°, 36.0°, 47.8°, 50.4° and 51.8° correspond to the (110), (011), (101), (111), (120), (211), (002) and (130) crystal planes in the CoSe2 standard card. In addition, two peaks were observed at 13.4° and 15.5°, which may be related to two high-temperature hydrothermal treatments. The XRD peak positions of catalysts FC40, FC60 and FC80 are similar to those of pure FeSe2, and due to the different doping amounts of CoSe2, a weak associated peak can be observed in FC80 near the peak of FeSe2, indicating that the introduction of CoSe2 will not affect the crystal structure of FeSe2, further indicating the successful preparation of FeSe2 / CoSe2 catalysts. It is worth noting that a few literature reports indicate that the Raman spectral vibrations of selenides mainly involve the stretching vibrations of selenium pairs (Se-Se) and the vibrations between transition metals and selenium. Figure 3 The Raman spectrum of FeSe2 in b shows that the -1 The characteristic peak at 181 cm-1 can be assigned to the Fe-Se bond vibration, while the Raman peak of CoSe2 is 181 cm-1 -1 and 670cm -1 , which are attributed to Se-Se bond and Co-Se bond respectively. In addition, at 466cm -1 The peak is due to the vibration of the O-Co-O bending mode under high temperature environment. The results further show that the FeSe2 / CoSe2 catalyst is successfully prepared.

[0063] XPS technology deeply analyzes the essence of charge transfer between the valence states of elements in FeSe2, CoSe2 and FC80 materials. Figure 4 a is a full spectrum scan, from which it can be observed that the material shows Fe, Co, and Se element signals, which is consistent with the EDS element mapping results. Figure 4b is the high-resolution spectrum of C1s, and the binding energies at 282.5eV, 284.8eV and 287.3eV are attributed to CC, C=C / CC and C=O bonds, respectively. In the high-resolution Fe 2p spectrum of FeSe2 sample ( Figure 4 c), the six fitting peaks are located at 707.2 eV (2p 3 / 2 ,Fe 2+ )、710.0eV(2p 3 / 2 ,Fe 3+ )、711.2eV(Fe 3+ )、713.3eV(2p 3 / 2 ,Fe 3+ )、720.0eV(2p 1 / 2 ,Fe 2+ ) and 724.1eV(2p 1 / 2 ,Fe 3+ ), 726.4eV (Sat.), which is consistent with the peak of FC80. Compared with FeSe2, the charge chemical transfer is shifted to the position with high binding energy, and the electron density is reduced, indicating that a large amount of electrons are provided to the reaction system and the chemical stability of the material is enhanced. In addition, the peaks of 716.0eV and 718.0eV in FC80 are both satellite peaks. These results show that Fe in the catalytic system 2+ / Fe 3+ It has an excellent activation effect on PMS, promoting the microelectron circulation between the two, thereby improving the catalytic activity. Figure 4 d is the 2p orbital of Co. The main binding energy in the FC80 sample is 779.1 eV (Co 2+ ) and 781.1eV(Co 3 + ), 783.7eV and 788.9eV are attributed to the 2p 3 / 2 orbital, at 794.1eV (Co 0 )、797.4eV(Co 2+ )、798.1eV(Co 3+ ) and 801.4eV(Co 3+ ) peak is attributed to 2p 1 / 2 In addition, the peaks at 786.5eV and 803.0eV in FC80 and 785.7eV and 803.4eV in CoSe2 are satellite peaks. The XPS spectrum of Se 3d is shown in Figure 4 e, the binding energy of FC80 is 55.1 eV (3d 3 / 2 ) and 56.0eV(3d 5 / 2) belongs to the Co-Se bond. In addition, the binding energy at 59.6 eV may be the strong interaction between Se and O atoms. Interestingly, the XPS binding energy in FC80 is generally shifted by 0.1-0.8 eV (Fe 2p) in the positive direction, 0.1-1.4 eV (Co2p) in the negative direction, and 0.2-0.7 eV (Se 3d) in the negative direction compared with FeSe2 and CoSe2, respectively. Combined with the XPS analysis results of the above materials, it is shown that there is a strong charge substitution between CoSe2 and FeSe2, and the charge change of Co is the largest. Therefore, the contribution of Co in the electron conduction process is crucial. It can contribute more effective electrons during the photocatalytic degradation of pollutants, thereby adsorbing and enhancing the ability of PMS to mineralize metronidazole. (Confirmed in the subsequent photocatalytic experiment). The optical properties of FeSe2, CoSe2 and FeSe2 / CoSe2 catalysts were studied by ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). Figure 4 f shows that in the visible light range of 200-800nm, the light absorption of single CoSe2 or FeSe2 materials is low. When the two are compounded, the light absorption capacity of FC40, FC60 and FC80 gradually increases and becomes extensive. Although there are differences in the light response intensity of the catalysts, it proves that the synthesized materials have good response to light and have the potential to be used in a wider wavelength range.

[0064] The activation ability of the catalyst for PMS was investigated by degrading MNZ, such as Figure 5 As shown in a. The degradation efficiency of MNZ in the degradation systems FC80 and FC80 / Vis is negligible. However, as the catalytic conditions change, the degradation effect changes significantly, and the degradation efficiencies of PMS, FeSe2 / PMS, CoSe2 / PMS, CoSe2 / PMS / Vis, FeSe2 / PMS / Vis and FC80 / PMS systems reach 28%, 54%, 47%, 59%, 80% and 72%, respectively. This result confirms that the construction of FeSe2-CoSe2 effectively improves the catalytic performance of FeSe2. Interestingly, after the addition of visible light, the degradation efficiency is greatly improved, and the degradation efficiency of the FC80 / PMS / Vis system is as high as 99% within 20 minutes. As shown in Figure 5 b shows Figure 5 The k value of the reaction time in the degradation process corresponding to a can be found that compared with other systems, k in the FC80 / PMS / Vis system is 0.04507min -1 is the highest, both 2.3 times that of FeSe2 / PMS and CoSe2 / PMS, further indicating that the FC80 / PMS / Vis system has attractive degradation activity. Figure 5c and 5d show that as the doping amount of CoSe2 changes from 40-80 mg, the corresponding kinetic rate changes positively correlated, so that the degradation efficiency of MNZ is increased to 99%. The results show that increasing the doping amount of CoSe2 greatly improves the excellent light capture potential of the catalyst, making the FC80 / PMS / Vis system show excellent mineralization ability.

[0065] The change of catalyst surface charge is mainly affected by the pH value of the solution, which can affect the formation of free radicals by adjusting the adsorption capacity of the catalyst surface to PMS. Figure 6 As shown in Figure a, the stability of the catalyst was investigated in the range of pH = 3-11. The results showed that under strong acidic conditions (pH = 3.0), the catalytic degradation efficiency of MNZ by the FC80 / PMS / Vis system was 83%. This may be due to the high H + Strong acidic conditions at concentrations will quench SO4 ·- The results showed that the FC80 catalyst maintained good catalytic activity in a wide pH range.

[0066] In addition, the effects of PMS concentration, catalyst dosage and MNZ concentration under different conditions were explored to obtain the optimal mineralization system. Figure 6 b shows that as the PMS concentration increases from 0mM to 2mM, the catalytic activity suddenly increases when it reaches 2mM, indicating that the system undergoes strong PMS activation and the MNZ removal effect is significantly improved with the increase of active groups in the system. Figure 6 c shows that when the PMS concentration is 2 mM, the degradation efficiency of OFX increases positively when the catalyst dosage increases from 0.1 g / L to 0.4 g / L. Figure 6 d further shows that when the OFX concentration is 10, 20, 30 and 40 mg / L, the degradation efficiency is 100%, 99%, 86% and 83%, respectively. Even at a concentration of 40 mg / L, the removal effect of material FC80 on MNZ is still as high as 83%, which confirms the excellent catalytic ability of the FC80 / PMS / Vis system. Finally, considering the catalytic performance and economic benefits, the optimal catalytic conditions were determined to be 2 mM PMS, 0.4 g / L catalyst and 20 mg / L MNZ.

[0067] Research on factors affecting MNZ

[0068] The stability of the catalyst is crucial in the process of antibiotic elimination. We selected four different water qualities for investigation, mainly including (from Henan Xinxiang Medical College): river water (Zhaoding River), lake water (Boyue Lake), tap water and deionized water to compare the degradation effect of MNZ. Figure 7It can be concluded from a that the degradation efficiency of MNZ is slightly reduced in lake water, while it maintains excellent degradation performance in river water, tap water and deionized water. In general, the prepared catalyst has good applicability and shows potential for practical application. Interestingly, different categories of antibiotics were selected to explore its universality. Figure 7 The results in b show that under the same catalytic conditions, within 20 minutes, the degradation efficiencies of tetracycline, ofloxacin and sulfamethoxazole were 96.5%, 82.2% and 73.6%, respectively. The FC80 catalyst showed the characteristics of generally efficient degradation of common pollutants. It is worth noting that the degree of metal ion leaching during the entire catalytic process was analyzed by ICP-OES. The leaching results of cobalt (Co) and iron (Fe) ions of the used catalyst were 0.9380 mg / L and 0.4564 mg / L, respectively, indicating that the material has a good metal leaching inhibition effect. Figure 7 c is a cycle experiment of FC80 catalyst. After 4 cycles, the elimination effect of MNZ was maintained at 90%. Ions and organic matter inevitably exist in natural water, and usually affect the effect of advanced oxidation processes through different physical or chemical effects. - 、NO3 - 、SO4 2- and H2PO4 - The concentration was set at 10 mM for anti-interference tests to explore the effect of inorganic anions on the catalytic performance of MNZ ( Figure 7 d) It can be seen from the figure that the exogenously added NO3 - and HCO3 - The catalytic degradation of MNZ was less affected by Cl - 、SO4 2- and H2PO4 - The introduction of Cl - The inhibitory effect of SO4 2- and H2PO4 - A possible explanation is that many anions can remove h through the following reaction + This scavenging mechanism leads to the reduction of available electrons and free radicals such as hydroxyl, which loses efficiency in the degradation process, see formula (Eq.2-3). - Oxidized by photoholes to chlorine radicals (Cl·), which are reduced by electrons to Cl2 ·- , thus reducing the available holes and electrons. On the other hand, chlorine radicals can be added / eliminated by addition / elimination reactions (E0(Cl · / Cl - )=2.5V) reacts with organic pollutants, reducing the effect of pollutant removal. SO4 2-and H2PO4 - The slight decrease may be related to the consumption of some PMS active groups, see formula (Eq. 4).

[0069] Cl - +h + →Cl· (2)

[0070]

[0071] It can be seen from the above embodiments that the present invention provides a FeSe2 / CoSe2 catalyst and its preparation method and application. Highly electronegative Se can produce a strong synergistic effect with transition metals to form transition metal selenides, and its excellent conductivity and efficient charge mobility become key factors for activating PMS. The present invention selects selenide as a carrier to prepare FeSe2 / CoSe2 catalysts for the study of PMS activation and degradation mechanism. The prepared catalysts are analyzed by advanced technologies such as XRD, XPS, HRTEM / FESEM, and Raman for the morphology and surface chemical state of the catalysts. The characterization results show that diamond-shaped FeSe2 and flaky CoSe2 form three excellent catalysts. Such a construction exhibits excellent charge transfer capabilities and provides a large number of active reaction sites, thereby improving the activation efficiency of PMS and obtaining an efficient degradation of antibiotics.

[0072] The degradation ability of the catalyst on organic pollutants and the optimal reaction conditions (catalyst dosage, PMS concentration and antibiotic concentration, etc.) were explored. The results showed that FeSe2 / CoSe2 / PMS / Vis could achieve a 99% removal effect on metronidazole within 20 minutes. The influencing factor test was used to evaluate the stability, universality and environmental friendliness of the prepared catalyst. The present invention provides a relatively feasible solution for treating persistent and complex organic matter in the environment, and also provides ideas for the preparation of efficient new PMS activators.

[0073] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a FeSe2 / CoSe2 catalyst, characterized in that: The following steps are involved: (1) mixing a ferrous chloride solution and a selenium solution and performing a solvothermal reaction, and drying the product to obtain FeSe2; (2) After CoSe2 is dispersed in water, FeSe2 is added and ultrasonically mixed, followed by a hydrothermal reaction. After the product is dried, a FeSe2 / CoSe2 catalyst is obtained.

2. The preparation method according to claim 1, characterized in that: The temperature of the solvent thermal reaction is 150-170° C., and the reaction time is 10-14 hours.

3. The preparation method according to claim 1 or 2, characterized in that: The temperature of the hydrothermal reaction is 170-190° C., and the reaction time is 8-12 hours.

4. The preparation method according to claim 3, characterized in that: The ferrous chloride solution is obtained by dissolving FeCl2·4H2O in ethanolamine, and the mass concentration of the ferrous chloride solution is 30-50 g / L.

5. The preparation method according to claim 1, 2 or 4, characterized in that: The selenium solution is obtained by dissolving Se powder in ethanolamine, and the mass concentration of the selenium solution is 13-15 g / L.

6. The preparation method according to claim 5, characterized in that: In the step (1), the drying temperature is 50 to 70° C. and the drying time is 10 to 14 hours.

7. The preparation method according to claim 1, 2, 4 or 6, characterized in that: The mass ratio of CoSe2 to FeSe2 is 40-80 mg:0.1 g, the dosage ratio of CoSe2 to water is 40-80 mg:60 mL; and the ultrasonic mixing time is 3-5 min.

8. The preparation method according to claim 7, characterized in that: In the step (2), the drying temperature is 50 to 70° C. and the drying time is 10 to 14 hours.

9. The FeSe2 / CoSe2 catalyst prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the FeSe2 / CoSe2 catalyst according to claim 9 in activating peroxymonosulfate to degrade metronidazole.

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