CoAl-LDO / MoS2 heterojunction ozone catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalysts for sewage treatment, and particularly relates to a CoAl-LDO / MoS2 heterojunction ozone catalyst as well as a preparation method and application thereof. The preparation method comprises the following steps: preparing a MoS2 precursor; dispersing the MoS2 precursor, a cobalt salt, an aluminum salt and a precipitant into deionized water for ultrasonic dispersion, stirring, and carrying out a hydrothermal reaction; centrifugally collecting a product, washing, drying and calcining to obtain the CoAl-LDO / MoS2 heterojunction ozone catalyst. The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst provided by the invention is simple in process and mild in reaction condition; the prepared ozone catalyst is applied to degradation of antibiotics, and the effect is good. The ozone catalyst provided by the invention has the advantages of large specific surface area, high accessibility of active sites, difficulty in inactivation of oxygen vacancies, good stability and good degradation effect on tetracycline hydrochloride, levofloxacin and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts for sewage treatment, and particularly relates to a CoAl-LDO / MoS2 heterojunction ozone catalyst, a preparation method thereof and an application thereof. Background Art

[0002] As an important drug for treating infections, inhibiting bacteria and viruses, antibiotics are applied in multiple fields such as human medicine, livestock and poultry breeding, and aquaculture, and are discharged into the natural environment through various channels, posing a great threat to the ecological environment and human health. As a new type of pollutant, due to its diverse types, complex structures, and unclear environmental effects, it is particularly difficult to remove trace-level antibiotics in sewage. At present, the methods for treating sewage containing antibiotics include adsorption method, membrane separation method, biological treatment method, etc. However, the adsorption method only realizes the migration of pollutants from the aqueous phase to the solid phase, and fails to achieve the complete degradation or harmless treatment of pollutants; the membrane separation method also fails to achieve the complete degradation of pollutants, and organic substances, suspended particles, and microorganisms in the water body are easily formed on the membrane surface to form a pollution layer, resulting in a significant decrease in membrane flux and separation efficiency; the biological treatment method is relatively sensitive to the types, concentrations, and environmental parameters (such as temperature, pH value, nutrients, etc.) of pollutants, is extremely vulnerable to environmental fluctuations, and has relatively slow efficiency. In contrast, the catalytic ozonation technology, as an efficient advanced oxidation process, exhibits significant advantages in the removal of organic pollutants due to its strong oxidation ability. It can quickly break the chemical structure of complex organic molecules and convert them into inorganic substances or intermediate products that are easy to treat subsequently.

[0003] Oxygen vacancy (OV) is a key active site in ozone catalysts, and its unique anion defect structure characteristics have a decisive influence on the catalytic performance of the material. The absence of lattice oxygen atoms forms oxygen vacancy defects on the catalyst surface, showing a relatively low formation energy. In redox reaction systems such as catalytic ozonation, oxygen vacancies play a core catalytic role through a dynamic electron transfer mechanism. Specifically, the local electron-rich characteristics caused by the absence of lattice oxygen endow oxygen vacancies with a strong ozone adsorption ability: O3 realizes stable surface adsorption by embedding its O atoms into the oxygen vacancy defect sites on the catalyst surface. Subsequently, oxygen vacancies, as electron donors, drive electrons to transfer directionally to the adsorbed ozone molecules; this interfacial electron transfer process significantly prolongs the O-O bond in ozone molecules, promoting the spontaneous dissociation of ozone molecules into surface-bound atomic oxygen and gaseous oxygen molecules, and then generating key reactive oxygen species (ROS) such as •OH and •O2 - through a chain reaction. Finally, the peroxides generated on the surface decompose to release gaseous O2, and the oxygen vacancies are regenerated and participate in the next round of ozone decomposition cycle again.

[0004] CN119771388A discloses a preparation method of a heterogeneous ozone catalyst. In view of the problems of ozone oxidation such as selectivity, too fast decomposition rate, slow mass transfer rate, low solubility, etc., a preparation method of an ozone catalyst with boron trioxide loaded on the surface and inside of a porous support is proposed. It is pointed out that since there are oxygen defects (oxygen vacancies) in boron trioxide, it can effectively improve the efficiency of boron trioxide in catalyzing ozone, enhance the decomposition ability of ozone, generate a large amount of hydroxyl radicals (•OH), and thus efficiently degrade organic substances in sewage. However, this method only utilizes the oxygen vacancies inherent in boron trioxide itself and does not treat the catalyst to further increase the content of active sites (oxygen vacancies).

[0005] CN119406396A discloses an oxygen vacancy-rich perovskite catalyst for the advanced treatment of ozone catalytic oxidation of organic pollutant wastewater. By using the citrate sol-gel method and adjusting the ratio of Ca and Mn, a series of oxygen vacancy-rich perovskite catalysts with different Ca / Mn ratios are synthesized, and the generation of superoxide radicals (•O2 - )is induced by oxygen vacancies, and finally the degradation of organic pollutants is realized. However, the ozone decomposition rate (i.e., the catalyst activity) not only depends on the OV density, but also on the decomposition rate of intermediate oxygen species. If the peroxide decomposition is insufficient, the OV will be occupied by intermediate oxygen species or converted into lattice oxygen, resulting in the inability to regenerate the vacancies and the increase of the average oxidation state of transition metals, and the catalyst activity gradually deactivates. In addition, due to the strong competitive adsorption of water molecules at the OV, the catalyst is very easy to deactivate in the aqueous phase. Therefore, only reducing the average oxidation state of transition metals or increasing the oxygen vacancy content during the preparation process cannot fundamentally solve the problem that the catalyst is prone to deactivate during the reaction process. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the above-mentioned defects existing in the prior art, and provide a preparation method of a CoAl-LDO / MoS2 heterojunction ozone catalyst, which has a simple process and mild reaction conditions; applying the prepared ozone catalyst to the degradation of antibiotics has good effects, and provides a new solution for the treatment of industrial antibiotic wastewater. The present invention also provides a CoAl-LDO / MoS2 heterojunction ozone catalyst, which has a large specific surface area, high accessibility of active sites, oxygen vacancies that are not easily deactivated and good stability, and has good degradation effects on tetracycline hydrochloride, levofloxacin, etc.

[0007] Preparation method of CoAl-LDO / MoS2 heterojunction ozone catalyst according to the present invention: The method includes the following steps: First, prepare a MoS2 precursor; then disperse the MoS2 precursor, cobalt salt, aluminum salt, and precipitant in deionized water for ultrasonic dispersion and stirring, and then carry out a hydrothermal reaction; finally, centrifuge to collect the product, wash, dry, and calcine to obtain the CoAl-LDO / MoS2 heterojunction ozone catalyst. By adopting a hydrothermal reaction and a chemical in-situ growth technique under mild conditions, the present invention synthesizes a CoAl-LDO / MoS2 heterojunction ozone catalyst.

[0008] The specific steps for preparing the MoS2 precursor are as follows: Disperse molybdate and sulfur source in deionized water for ultrasonic dispersion and stirring, and then carry out a hydrothermal reaction; centrifuge to collect the product, wash, and dry to obtain the MoS2 precursor. By controlling the dosages of the molybdate and sulfur source, the formation of MoS2 is ensured.

[0009] The molybdate is sodium molybdate and / or ammonium molybdate; the sulfur source is one of thiourea, thioacetamide, and sodium sulfide. The molybdate and sulfur source are calculated based on Mo and S respectively, and the molar ratio is 1:2 to 4.

[0010] The process parameters of the specific steps of the MoS2 precursor are as follows: The ultrasonic dispersion time is 10 - 15 min; the stirring time is 0.25 - 1 h; the centrifugation speed is 4000 - 8000 rpm; the drying temperature is 40 - 80 °C; the temperature of the hydrothermal reaction is 160 - 220 °C, and the time is 16 - 24 h.

[0011] The cobalt salt is one or more of cobalt nitrate, cobalt chloride, and cobalt sulfate; the aluminum salt is one or more of aluminum chloride, aluminum nitrate, and aluminum sulfate; the precipitant is one or more of urea, sodium hydroxide, ammonia water, and ammonium fluoride.

[0012] Disperse the MoS2 precursor, cobalt salt, aluminum salt, and precipitant in deionized water. The concentration of MoS2 is 1.1 - 5.5 g / L, the concentration of cobalt salt is 0.09 - 0.21 mol / L, the concentration of aluminum salt is 0.03 - 0.07 mol / L, and the concentration of precipitant is 0.4 - 1.8 mol / L. By controlling the dosage of the precipitant, the integrity and thickness of the CoAl-LDO flaky structure are adjusted, and ultimately the contact interface between the CoAl-LDO species and the MoS2 species in the CoAl-LDO / MoS2 heterojunction ozone catalyst is affected.

[0013] The molar concentration ratio of cobalt salt to aluminum salt is 1:0.2 to 0.6. By precisely controlling the appropriate dosage ratio of cobalt salt and aluminum salt, the correct nucleation of the hydroxide precursor unit cell of CoAl-LDO is ensured, and the atomic-level uniform distribution of Al and Co is achieved.

[0014] The ultrasonic dispersion time is 10 - 15 min; the stirring time is 0.25 - 1 h, which can ensure that the raw materials are evenly dispersed and fully contacted in the solvent, contribute to the subsequent hydrothermal reaction, and avoid the occurrence of agglomeration; the centrifugal speed is 4000 - 8000 rpm, which can ensure the full recovery of the product; the drying temperature is 40 - 80 °C, which can ensure the full drying of the product while maintaining a stable state; the temperature of the hydrothermal reaction is 90 - 120 °C, and the time is 8 - 12 h; during calcination, it is heated to 400 - 600 °C at a rate of 2 - 10 °C / min and maintained for 2 - 3 h, and the atmosphere during the calcination process is nitrogen or argon.

[0015] A CoAl-LDO / MoS2 heterojunction ozone catalyst is prepared by the preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst, and the mass ratio of CoAl-LDO to MoS2 is 1:0.1 - 0.5.

[0016] The application of the CoAl-LDO / MoS2 heterojunction ozone catalyst: It is used to catalytically oxidize and degrade antibiotic pollutants in water. The antibiotic pollutants can be tetracycline hydrochloride, levofloxacin, norfloxacin, and oxytetracycline hydrochloride. The concentration of the antibiotic pollutants in water is 100 - 400 mg / L, and the addition ratio of the CoAl-LDO / MoS2 heterojunction ozone catalyst in the antibiotic wastewater is 0.2 - 0.8 g / L. The ozone concentration of the catalytic ozonation process is 20 mg / L, the ozone flow rate is 0.2 - 1.0 L / min, the temperature is 25 °C, and the time is 20 - 40 min. The CoAl-LDO / MoS2 heterojunction ozone catalyst of the present invention is mixed with the antibiotic wastewater, stirred under dark conditions, and after reaching the adsorption equilibrium, a catalytic ozonation reaction is carried out under the condition of introducing ozone to complete the degradation treatment of the antibiotic pollutants.

[0017] By controlling the mass ratio of CoAl-LDO to MoS2 within the range of 1:0.1 to 0.5, the surface distribution and loading amount of CoAl-LDO and MoS2 are optimized, thereby forming a more uniform and dense heterojunction structure, which is conducive to the formation of pore structures and the construction of built-in electric fields, promotes the accessibility of active sites and the electron transfer efficiency, and ultimately improves the catalytic ozone oxidation efficiency. By controlling the hydrothermal reaction temperature and time, the present invention can ensure the growth of crystals of raw materials in the autoclave driven by high temperature and high pressure. In addition, the interfacial binding force between CoAl-LDO and MoS2 can be enhanced, thereby forming a more compact and uniform heterojunction structure. By regulating the calcination temperature, time and heating rate under the protection of nitrogen or argon atmosphere, it can ensure the complete transformation of the hydroxide precursor of CoAl-LDO, and further optimize the pore structure of the CoAl-LDO / MoS2 heterojunction ozone catalyst through the decomposition of interlayer anions and the overflow of water molecules. CoAl-LDO is a layered double metal hydroxide.

[0018] Specifically, the preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst includes the following steps: (1) Disperse molybdate and sulfur source in deionized water and mix them so that the molybdate concentration is 0.016 mol / L to 0.112 mol / L, the sulfur source concentration is 0.224 mol / L to 0.448 mol / L, and the dosage ratio of Mo atoms to S atoms is 1:2 to 4. After ultrasonic dispersion for 10 - 15 min, stir magnetically for 0.25 - 1 h until uniform to form a precursor solution; transfer the precursor solution to a hydrothermal autoclave and carry out hydrothermal reaction at 160 - 220 °C in an oven for 16 - 24 h. The product is separated and recovered in a centrifuge at 4000 - 8000 rpm, washed repeatedly 3 times with deionized water and alcohol, and then dried in an oven at 40 - 80 °C to constant weight to obtain a MoS2 precursor; (2) Disperse the MoS2 precursor, cobalt salt, aluminum salt, and precipitant into deionized water and mix them so that the concentration of the MoS2 precursor is 1.1 g / L to 5.5 g / L, the concentration of the cobalt salt is 0.09 - 0.21 mol / L, the concentration of the aluminum salt is 0.03 - 0.07 mol / L, the concentration of the precipitant is 0.4 - 1.8 mol / L, and the molar concentration ratio of the cobalt salt to the aluminum salt is 1:0.2 - 0.6. After ultrasonic dispersion for 10 - 15 min, stir magnetically for 0.25 - 1 h until homogeneous to form a precursor solution; transfer the precursor solution to a hydrothermal autoclave and carry out hydrothermal reaction at 90 - 120 °C in an oven for 8 - 12 h. Separate and recover the product in a centrifuge at 4000 - 8000 rpm, wash it repeatedly 3 times with deionized water and alcohol, and then dry it to constant weight at 40 - 80 °C in an oven; heat the dried product to 400 - 600 °C at a rate of 2 - 10 °C / min in a tube furnace under a nitrogen atmosphere protection and hold for 2 - 3 h to obtain the CoAl-LDO / MoS2 heterojunction ozone catalyst.

[0019] The present invention uses hydrothermal reaction and chemical in-situ growth technology under mild conditions to synthesize a CoAl-LDO / MoS2 heterojunction ozone catalyst. Specifically, a certain amount of molybdate and thiourea are dispersed into deionized water, and hydrothermal reaction is carried out under certain conditions to generate MoS2. Subsequently, a certain amount of the prepared MoS2, cobalt salt, aluminum salt, and precipitant are dispersed into deionized water, and hydrothermal reaction is carried out under certain conditions. The product is calcined under an inert atmosphere protection to form a tight heterojunction structure, and the CoAl-LDO / MoS2 heterojunction ozone catalyst is obtained.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst of the present invention is simple in operation, mild in reaction conditions, and low in cost. The obtained ozone catalyst has a good degradation effect on antibiotics, provides a new solution for the treatment of industrial antibiotic wastewater, and has broad application prospects.

[0021] (2) The CoAl-LDO / MoS2 heterojunction ozone catalyst prepared by the method of the present invention, due to the work function difference between CoAl-LDO and MoS2, with CoAl-LDO as a p-type semiconductor and MoS2 as an n-type semiconductor, when the contact interface is constructed between the two, a built-in electric field in which electrons transfer from MoS2 to CoAl-LDO will be formed at the interface. This built-in electric field will promote the redox cycle of transition metal Co ions in CoAl-LDO and ultimately achieve the regeneration of oxygen vacancies; MoS2, as an electron-deficient center, will spontaneously capture electrons in organic pollutants to achieve the dynamic regeneration of oxygen vacancies during the catalytic ozone oxidation reaction; compared with artificially reducing the average oxidation state of transition metals and increasing the oxygen vacancy content during preparation, it can achieve the long-term stability and availability of the ozone catalyst.

[0022] (3) Applying the CoAl-LDO / MoS2 heterojunction ozone catalyst prepared by the present invention to the degradation of antibiotics in sewage has good universality. Description of the Drawings

[0023] Figure 1 SEM image of the CoAl-LDO / MoS2 heterojunction ozone catalyst obtained in Example 1.

[0024] Figure 2 TEM image of the CoAl-LDO / MoS2 heterojunction ozone catalyst obtained in Example 1.

[0025] Figure 3 Graph showing the change in absorbance of the pollutant solution with illumination time when the catalysts prepared in Examples 1-5 and Comparative Examples 1-6 are applied to the degradation of antibiotics in sewage.

[0026] Figure 4 Graph showing the change in degradation concentration over time of tetracycline hydrochloride, levofloxacin, norfloxacin, and oxytetracycline hydrochloride in sewage by the catalyst prepared in Example 1.

[0027] Figure 5 Graph showing the result of the degradation activity of the catalyst prepared in Example 1 for tetracycline hydrochloride in sewage after 10 cycles of use. Detailed Embodiments

[0028] The present invention will be further described below in conjunction with specific embodiments.

[0029] The raw materials and auxiliaries used in the following examples and comparative examples are all commercially available products.

[0030] Example 1 The preparation method of the described CoAl-LDO / MoS2 heterojunction ozone catalyst includes the following steps: (1) Mix (NH4)6Mo7O24 · 4H2O and CH4N2S were dispersed in deionized water and mixed to make (NH4)6Mo7O 24 · 4H2O be 0.016 mol / L and CH4N2S be 0.224 mol / L. After ultrasonic dispersion for 15 min, magnetic stirring was carried out for 1 h until homogeneous to form a precursor solution; the precursor solution was transferred to a hydrothermal autoclave and hydrothermally reacted at 200 °C in an oven for 20 h. The product was separated and recovered in a centrifuge at 6000 rpm, washed repeatedly with deionized water and alcohol three times, and then dried in an oven at 60 °C to constant weight to obtain the MoS2 precursor; (2) MoS2 precursor, Co(NO3)2·6H2O, Al(NO3)3·9H2O and CO(NH2)2 were dispersed in deionized water and mixed to make the MoS2 precursor be 1.10 g / L, Co(NO3)2·6H2O be 0.12 mol / L, Al(NO3)3·9H2O be 0.04 mol / L, and CO(NH2)2 be 1.70 mol / L. After ultrasonic dispersion for 15 min, magnetic stirring was carried out for 1 h until homogeneous to form a precursor solution; the precursor solution was transferred to a hydrothermal autoclave and hydrothermally reacted at 100 °C in an oven for 10 h. The product was separated and recovered in a centrifuge at 6000 rpm, washed repeatedly with deionized water and alcohol three times, and then dried in an oven at 60 °C to constant weight; the dried product was calcined in a tubular furnace under the protection of a nitrogen atmosphere, heated to 500 °C at a rate of 5 °C / min and held for 2 h to obtain the CoAl-LDO / MoS2 heterojunction ozone catalyst, and the mass ratio of CoAl-LDO to MoS2 was 1:0.1.

[0031] The SEM image of the prepared CoAl-LDO / MoS2 heterojunction ozone catalyst is as Figure 1 shown, and it can be seen from Figure 1 that the CoAl-LDO / MoS2 heterojunction ozone catalyst presents a microflower structure formed by regular sheet stacking. The sheets have a large aspect ratio, which endows it with a large specific surface area and provides sufficient reactive sites for reactants (ozone and organic pollutants). The microflower structure can provide channels for the reaction of ozone and organic pollutants inside the catalyst and promote the contact of reactants based on the confinement effect.

[0032] The TEM image of the prepared CoAl-LDO / MoS2 heterojunction ozone catalyst is as Figure 2 shown, and it can be seen from Figure 2It can be seen that the micron flower structure of the CoAl-LDO / MoS2 heterojunction ozone catalyst is jointly formed by the curved nano flower structure provided by MoS2 and the flat sheet structure provided by CoAl-LDO. Since CoAl-LDO carries a positive charge and MoS2 carries a negative charge, based on the electrostatic adsorption effect, the two form a close contact, significantly promoting the electron transfer in the heterojunction catalyst material.

[0033] Example 2 The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst described above includes the following steps: (1) Disperse (NH4)6Mo7O 24 ·4H2O and CH4N2S in deionized water and mix them so that the concentration of (NH4)6Mo7O 24 ·4H2O is 0.016 mol / L and the concentration of CH4N2S is 0.448 mol / L. After ultrasonic dispersion for 15 min, stir magnetically for 1 h until homogeneous to form a precursor solution; transfer the precursor solution to a hydrothermal reactor and carry out hydrothermal reaction at 160 °C in an oven for 24 h. The product is separated and recovered in a centrifuge at 4000 rpm, washed repeatedly 3 times with deionized water and alcohol, and then dried in an oven at 40 °C to constant weight to obtain the MoS2 precursor; (2) Disperse the MoS2 precursor, Co(NO3)2·6H2O, Al(NO3)3·9H2O, and NaOH in deionized water and mix them so that the concentration of the MoS2 precursor is 5.50 g / L, the concentration of Co(NO3)2·6H2O is 0.21 mol / L, the concentration of Al(NO3)3·9H2O is 0.07 mol / L, and the concentration of NaOH is 1.70 mol / L. After ultrasonic dispersion for 15 min, stir magnetically for 1 h until homogeneous to form a precursor solution; transfer the precursor solution to a hydrothermal reactor and carry out hydrothermal reaction at 90 °C in an oven for 12 h. The product is separated and recovered in a centrifuge at 4000 rpm, washed repeatedly 3 times with deionized water and alcohol, and then dried in an oven at 40 °C to constant weight; heat the dried product in a tubular furnace under the protection of a nitrogen atmosphere, raise the temperature to 400 °C at a rate of 2 °C / min and hold for 3 h to obtain the CoAl-LDO / MoS2 heterojunction ozone catalyst. The obtained CoAl-LDO / MoS2 heterojunction ozone catalyst has a mass ratio of CoAl-LDO to MoS2 of 1:0.3.

[0034] Example 3 The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst described above includes the following steps: (1) Disperse Na2MoO4·2H2O and C2H5NS in deionized water and mix them so that the concentration of Na2MoO4·2H2O is 0.112 mol / L and the concentration of C2H5NS is 0.224 mol / L. After ultrasonic dispersion for 15 min, stir magnetically for 0.25 h until homogeneous to form a precursor solution; transfer the precursor solution to a hydrothermal autoclave and carry out hydrothermal reaction at 220 °C in an oven for 16 h. The product is separated and recovered in a centrifuge at 8000 rpm, washed repeatedly 3 times with deionized water and alcohol, and then dried in an oven at 80 °C to constant weight to obtain a MoS2 precursor; (2) Disperse the MoS2 precursor, CoCl2·6H2O, AlCl3·6H2O and NH3·H2O in deionized water and mix them so that the concentration of the MoS2 precursor is 5.50 g / L, the concentration of CoCl2·6H2O is 0.09 mol / L, the concentration of AlCl3·6H2O is 0.03 mol / L, and the concentration of NH3·H2O is 0.80 mol / L. After ultrasonic dispersion for 15 min, stir magnetically for 0.25 h until homogeneous to form a precursor solution; transfer the precursor solution to a hydrothermal autoclave and carry out hydrothermal reaction at 120 °C in an oven for 8 h. The product is separated and recovered in a centrifuge at 8000 rpm, washed repeatedly 3 times with deionized water and alcohol, and then dried in an oven at 80 °C to constant weight; heat the dried product in a tubular furnace under the protection of an argon atmosphere, raise the temperature to 600 °C at a rate of 10 °C / min and hold for 2 h to obtain a CoAl-LDO / MoS2 heterojunction ozone catalyst, and the mass ratio of CoAl-LDO to MoS2 is 1:0.5.

[0035] Example 4 The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst described above includes the following steps: (1) Disperse Na2MoO4·2H2O and Na2S in deionized water and mix them so that the concentration of Na2MoO4·2H2O is 0.112 mol / L and the concentration of Na2S is 0.224 mol / L. After ultrasonic dispersion for 10 min, stir magnetically for 1 h until homogeneous to form a precursor solution; transfer the precursor solution to a hydrothermal autoclave and carry out hydrothermal reaction at 200 °C in an oven for 20 h. The product is separated and recovered in a centrifuge at 6000 rpm, washed repeatedly 3 times with deionized water and alcohol, and then dried in an oven at 60 °C to constant weight to obtain a MoS2 precursor; (2) Disperse MoS2 precursor, CoSO4·7H2O, Al2(SO4)3·16H2O, CO(NH2)2 and NH4F into deionized water and mix them so that the concentration of MoS2 precursor is 1.10 g / L, CoSO4·7H2O is 0.09 mol / L, Al2(SO4)3·16H2O is 0.054 mol / L, CO(NH2)2 is 1.60 mol / L, and NH4F is 0.20 mol / L. After ultrasonic dispersion for 10 min, stir magnetically for 1 h until homogeneous to form a precursor solution; transfer the precursor solution to a hydrothermal reactor and carry out hydrothermal reaction at 100 °C in an oven for 10 h. The product is separated and recovered in a centrifuge at 6000 rpm, washed repeatedly with deionized water and alcohol three times, and then dried to constant weight at 60 °C in an oven; heat the dried product to 500 °C at a rate of 5 °C / min and hold for 2 h in a tubular furnace under the protection of an argon atmosphere to obtain a CoAl-LDO / MoS2 heterojunction ozone catalyst, and the mass ratio of CoAl-LDO to MoS2 is 1:0.1.

[0036] Example 5 The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst described above includes the following steps: (1) Disperse (NH4)6Mo7O 24 ·4H2O and CH4N2S into deionized water and mix them so that the concentration of (NH4)6Mo7O 24 ·4H2O is 0.016 mol / L and CH4N2S is 0.224 mol / L. After ultrasonic dispersion for 15 min, stir magnetically for 1 h until homogeneous to form a precursor solution; transfer the precursor solution to a hydrothermal reactor and carry out hydrothermal reaction at 200 °C in an oven for 20 h. The product is separated and recovered in a centrifuge at 6000 rpm, washed repeatedly with deionized water and alcohol three times, and then dried to constant weight at 60 °C in an oven to obtain a MoS2 precursor; (2)Disperse the MoS2 precursor, Co(NO3)2·6H2O, Al(NO3)3·9H2O, and CO(NH2)2 in deionized water and mix them so that the concentration of the MoS2 precursor is 1.10 g / L, the concentration of Co(NO3)2·6H2O is 0.21 mol / L, the concentration of Al(NO3)3·9H2O is 0.042 mol / L, and the concentration of CO(NH2)2 is 1.70 mol / L. After ultrasonic dispersion for 15 min, stir magnetically for 1 h until homogeneous to form a precursor solution; transfer the precursor solution to a hydrothermal autoclave and carry out hydrothermal reaction at 100 °C in an oven for 10 h. The product is separated and recovered in a centrifuge at 6000 rpm, washed repeatedly 3 times with deionized water and alcohol, and then dried in an oven at 60 °C to constant weight; the dried product is placed in a tubular furnace under the protection of a nitrogen atmosphere, heated to 500 °C at a rate of 5 °C / min and maintained for 2 h to obtain a CoAl-LDO / MoS2 heterojunction ozone catalyst, and the mass ratio of CoAl-LDO to MoS2 is 1:0.1.

[0037] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that step (1) is omitted, and MoS2 is not added in step (2), that is, pure CoAl-LDO is prepared by the same method as in step (2) of Example 1.

[0038] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that step (2) is omitted, that is, pure MoS2 is prepared by the same method as in step (1) of Example 1.

[0039] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that Al(NO3)3·9H2O in step (2) is removed, and the other preparations are exactly the same as in Example 1.

[0040] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that Co(NO3)2·6H2O in step (2) is removed, and the other preparations are exactly the same as in Example 1.

[0041] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that the concentration of the MoS2 precursor in step (2) is replaced with 10 g / L, and the other preparations are exactly the same as in Example 1.

[0042] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that the calcination temperature in step (2) is replaced with 800 °C, and the other preparations are exactly the same as in Example 1.

[0043] Experiment 1: The specific surface area, pore size, and pore volume results of the catalysts prepared in the above examples and comparative examples are shown in Table 1.

[0044] Table 1 Specific surface area, pore size and pore volume results of the catalyst

[0045] Experiment 2: To investigate the effect of the catalysts obtained in the above examples and comparative examples on removing antibiotic pollutants in antibiotic wastewater, the catalysts obtained in the examples and comparative examples were added to antibiotic wastewater with a hydrochloric acid tetracycline concentration of 300 mg / L. The addition ratio of each group of catalysts was 0.6 g / L, and they were stirred and mixed evenly at 1000 rpm. Stirring was carried out for 30 min in the dark to reach adsorption and desorption equilibrium. The catalytic ozonation experiment was carried out in a 1000 mL reactor at 25 °C, with an ozone concentration of 20 mg / L and an ozone flow rate of 0.5 L / min. At specific time intervals, 3 mL of the degraded solution was taken, centrifuged thoroughly first, and then the supernatant was taken. After filtering with a 0.22 μm filter head, the absorbance of the solution was measured using a UV-visible spectrophotometer at the characteristic wavelength of the pollutant, and the change value of the absorbance of the pollutant solution with the illumination time was recorded. The test results are as Figure 3 shown.

[0046] It can be seen from the above that: Compared with the ozone catalyst obtained in the comparative example, the CoAl-LDO / MoS2 heterojunction ozone catalyst has a significantly higher degradation rate of hydrochloric acid tetracycline, reaching 80.39% after 10 min of catalytic ozonation degradation. This is because: (1) Compared with pure CoAl-LDO, due to the existence of the interfacial electric field, the CoAl-LDO / MoS2 heterojunction ozone catalyst contains more low-valent cobalt species, and thus has a higher content of active sites (oxygen vacancies); (2) Pure MoS2 itself does not have catalytic ozonation activity; (3) Compared with CoO and Al2O3, as a typical solid solution, CoAl-LDO contains a higher content of defects due to the introduction of heteroatoms, and thus has a higher content of oxygen vacancies; (4) Further increasing the composite amount of MoS2 cannot improve the performance of the CoAl-LDO / MoS2 heterojunction ozone catalyst, because the decrease in the composite amount of CoAl-LDO will lead to a decrease in the exposure amount of the active sites (oxygen vacancies) it can provide; (5) When the calcination temperature is too high, it will cause the CoAl-LDO component to lose its "structural memory effect", making it difficult to maintain its layered structure in the wastewater containing pollutants, resulting in a decrease in its adsorption performance and ultimately a decrease in the contact opportunity between the catalyst and the pollutants, leading to a decrease in its performance.

[0047] The above results show that the CoAl-LDO / MoS2 heterojunction ozone catalyst prepared by the present invention exhibits excellent performance in the degradation of tetracycline antibiotics, with a fast degradation rate and a high degradation rate, and has potential application value for environmental pollution control.

[0048] Experiment 3: In order to prove the degradation universality of the CoAl-LDO / MoS2 heterojunction ozone catalyst of the present invention, the CoAl-LDO / MoS2 heterojunction ozone catalyst obtained in Example 1 was added to wastewater containing tetracycline hydrochloride, levofloxacin, norfloxacin and oxytetracycline hydrochloride, respectively, wherein the concentrations of tetracycline hydrochloride, levofloxacin, norfloxacin and oxytetracycline hydrochloride in the wastewater were all 300 mg / L. The catalytic ozone oxidation degradation activity of the catalyst was tested by the method of Experiment 2. The results are as follows: Figure 4 shown.

[0049] From the above, it can be seen that the CoAl-LDO / MoS2 heterojunction ozone catalyst prepared by the present invention has excellent degradation activity for tetracycline hydrochloride, levofloxacin, norfloxacin and oxytetracycline hydrochloride within 10 minutes, and the degradation rate is not less than 60%, indicating that the CoAl-LDO / MoS2 heterojunction ozone catalyst of the present invention has good universality for the degradation of antibiotics.

[0050] Experiment 4: In order to prove the long-term stability of the CoAl-LDO / MoS2 heterojunction ozone catalyst of the present invention, its cyclic stability was evaluated by a system cycle experiment. The CoAl-LDO / MoS2 heterojunction ozone catalyst obtained in Example 1 was added to wastewater containing tetracycline hydrochloride, wherein the concentration of tetracycline hydrochloride in the wastewater was 300 mg / L, and the catalytic ozone oxidation degradation activity of the catalyst was tested using the method of Experiment 2. After the test, the catalyst was washed and dried and then recycled for 10 times. The results are as follows Figure 5 shown.

[0051] From the above, it can be seen that in 10 consecutive cycle tests, the tetracycline hydrochloride removal rate of the CoAl-LDO / MoS2 heterojunction ozone catalyst at 10 minutes of reaction time was always maintained above 70%. This excellent performance retention rate confirms that the built-in electric field of the heterojunction catalyst significantly improves the stability of the material, effectively overcoming the problem of oxygen vacancies being easily deactivated during the reaction process.

Claims

1. A preparation method of CoAl-LDO / MoS2 heterojunction ozone catalyst, characterized in that: It includes the following steps: First, prepare the MoS2 precursor; then disperse the MoS2 precursor, cobalt salt, aluminum salt, and precipitant into deionized water for ultrasonic dispersion and stirring, and then carry out a hydrothermal reaction; finally, centrifuge to collect the product, wash, dry, and calcine to obtain the CoAl-LDO / MoS2 heterojunction ozone catalyst.

2. The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst according to claim 1, characterized in that: The specific steps for preparing the MoS2 precursor are: Disperse molybdate and sulfur source into deionized water for ultrasonic dispersion and stirring, and then carry out a hydrothermal reaction; centrifuge to collect the product, wash, and dry to obtain the MoS2 precursor.

3. The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst according to claim 2, characterized in that: The molybdate is sodium molybdate and / or ammonium molybdate; the sulfur source is one of thiourea, thioacetamide, and sodium sulfide. The molybdate and sulfur source are calculated based on Mo and S respectively, and the molar ratio is 1:2 - 4.

4. The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst according to claim 2, characterized in that: The specific steps for preparing the MoS2 precursor are: The ultrasonic dispersion time is 10 - 15 min; the stirring time is 0.25 - 1 h; the centrifugation speed is 4000 - 8000 rpm; the drying temperature is 40 - 80 °C; the temperature of the hydrothermal reaction is 160 - 220 °C, and the time is 16 - 24 h.

5. The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst according to claim 1, wherein: The cobalt salt is one or more of cobalt nitrate, cobalt chloride, and cobalt sulfate; the aluminum salt is one or more of aluminum chloride, aluminum nitrate, and aluminum sulfate; the precipitant is one or more of urea, sodium hydroxide, ammonia water, and ammonium fluoride.

6. The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst according to claim 1, characterized in that: Disperse the MoS2 precursor, cobalt salt, aluminum salt, and precipitant into deionized water. The concentration of MoS2 is 1.1 - 5.5 g / L, the concentration of cobalt salt is 0.09 - 0.21 mol / L, the concentration of aluminum salt is 0.03 - 0.07 mol / L, and the concentration of precipitant is 0.4 - 1.8 mol / L.

7. The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst according to claim 6, characterized in that: The molar concentration ratio of cobalt salt to aluminum salt is 1:0.2 - 0.

6.

8. The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst according to claim 1, characterized in that: The ultrasonic dispersion time is 10 - 15 min; the stirring time is 0.25 - 1 h; the centrifugation speed is 4000 - 8000 rpm; the drying temperature is 40 - 80 °C; the temperature of the hydrothermal reaction is 90 - 120 °C, and the time is 8 - 12 h; during calcination, heat up to 400 - 600 °C at a rate of 2 - 10 °C / min and hold for 2 - 3 h. The atmosphere during the calcination process is nitrogen or argon.

9. A CoAl-LDO / MoS2 heterojunction ozone catalyst, characterized in that: It is prepared by the preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst according to any one of claims 1 - 8. The mass ratio of CoAl-LDO to MoS2 is 1:0.1 - 0.

5.

10. Use of the CoAl-LDO / MoS2 heterojunction ozone catalyst according to claim 9, characterized in that: It is used for catalytic ozonation to degrade antibiotic pollutants in water.

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