A CoAl-LDO / MoS2 heterojunction ozone catalyst and its preparation method and application

Abstract

The present invention belongs to the technical field of catalysts for sewage treatment, and in particular to a CoAl-LDO / MoS2 heterojunction ozone catalyst and its preparation method and application. The preparation of the present invention comprises the following steps: obtaining a MoS2 precursor; dispersing the MoS2 precursor, a cobalt salt, an aluminum salt and a precipitant into deionized water for ultrasonic dispersion and stirring, and performing a hydrothermal reaction; collecting the product by centrifugation, washing, drying and calcining to obtain a CoAl-LDO / MoS2 heterojunction ozone catalyst. The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst provided by the present invention has a simple process and mild reaction conditions; the obtained ozone catalyst is applied to the degradation of antibiotics, and the effect is good. The ozone catalyst of the present invention has a large specific surface area, high active site accessibility, oxygen vacancies that are not easily deactivated and good stability, and has a good degradation effect on tetracycline hydrochloride, levofloxacin, etc.

Description

Technical Field

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

[0002] Antibiotics, as important drugs for treating infections and inhibiting bacteria and viruses, are used in a variety of fields, including human medicine, livestock and poultry farming, and aquaculture. They are released into the natural environment through various pathways, posing a significant threat to the ecological environment and human health. As an emerging pollutant, their diverse nature, complex structure, and unknown environmental effects make the removal of trace antibiotics from wastewater particularly challenging. Currently, treatment methods for antibiotic-containing wastewater include adsorption, membrane separation, and biological treatment. However, adsorption only transfers pollutants from the aqueous phase to the solid phase and fails to completely degrade or render them harmless. Membrane separation also fails to completely degrade pollutants, and organic matter, suspended particles, and microorganisms in the water easily form a fouling layer on the membrane surface, significantly reducing membrane flux and separation efficiency. Biological treatment methods are sensitive to pollutant type and concentration, as well as environmental parameters (such as temperature, pH, and nutrients), making them highly susceptible to environmental fluctuations and relatively slow in efficiency. In contrast, catalytic ozone oxidation technology, as an efficient advanced oxidation process, has shown significant advantages in the removal of organic pollutants due to its strong oxidizing ability. It can quickly destroy the chemical structure of complex organic molecules and convert them into inorganic substances or intermediate products that are easy to subsequently process.

[0003] Oxygen vacancies (OV) are key active sites in ozone catalysts, and their unique anion defect structural characteristics have a decisive influence on the catalytic performance of the material. The lack of lattice oxygen atoms forms oxygen vacancy defects on the catalyst surface, which exhibit relatively low formation energy. In redox reaction systems such as catalytic ozone oxidation, oxygen vacancies play a core catalytic role through a dynamic electron transfer mechanism. Specifically, the local electron-rich characteristics caused by the lack of lattice oxygen give oxygen vacancies a strong ozone adsorption ability: O3 achieves stable surface adsorption by embedding its O atoms into the oxygen vacancy defect sites on the catalyst surface. Subsequently, the oxygen vacancies act as electron donors to drive the directional transfer of electrons to the adsorbed ozone molecules; this interfacial electron transfer process significantly extends the OO bond in the ozone molecule, prompting the ozone molecule to spontaneously dissociate into surface-bound atomic oxygen and gaseous oxygen molecules, and then generate •OH, •O2 through a chain reaction. - Finally, the peroxides generated on the surface decompose to release gaseous O2, and the oxygen vacancies are regenerated and re-participate in the next round of ozone decomposition cycle.

[0004] CN119771388A discloses a method for preparing a heterogeneous ozone catalyst. To address issues such as ozone oxidation selectivity, rapid decomposition, slow mass transfer, and low solubility, a method for preparing an ozone catalyst by loading boron trioxide on the surface and interior of a porous support is proposed. The method states that the presence of oxygen vacancies in boron trioxide effectively improves its efficiency in catalyzing ozone, enhancing its ability to decompose ozone and generating a large number of hydroxyl radicals (•OH), thereby efficiently degrading organic matter in wastewater. However, this method only utilizes the oxygen vacancies inherent in boron trioxide and does not treat the catalyst to further increase the number of active sites (oxygen vacancies).

[0005] CN119406396A discloses an oxygen-vacancy-rich perovskite catalyst for deep ozone catalytic oxidation treatment of organic pollutant wastewater. A series of oxygen-vacancy-rich perovskite catalysts with different Ca / Mn ratios were synthesized by adjusting the ratio of Ca and Mn using the citrate sol-gel method. The oxygen vacancies were used to induce superoxide radicals (•O2 - ) and ultimately achieve the degradation of organic pollutants. However, the ozone decomposition rate (i.e., catalyst activity) depends not only on the OV density, but also on the decomposition rate of intermediate oxygen species. If the peroxide is insufficiently decomposed, the OV will be occupied by intermediate oxygen species or converted into lattice oxygen, resulting in the inability to regenerate vacancies, an increase in the average oxidation state of the transition metal, and a gradual deactivation of the catalyst activity. 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, simply reducing the average oxidation state of the transition metal or increasing the oxygen vacancy content during the preparation process cannot fundamentally solve the problem of easy deactivation of the catalyst during the reaction. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the above-mentioned shortcomings of the prior art and provide a method for preparing a CoAl-LDO / MoS2 heterojunction ozone catalyst with a simple process and mild reaction conditions. The prepared ozone catalyst is effectively applied to the degradation of antibiotics, providing a new solution for the treatment of industrial antibiotic wastewater. The present invention also provides a CoAl-LDO / MoS2 heterojunction ozone catalyst with a large specific surface area, high active site accessibility, oxygen vacancies that are not easily deactivated, and good stability, showing good degradation effects on tetracycline hydrochloride, levofloxacin, and other substances.

[0007] The present invention discloses a method for preparing a CoAl-LDO / MoS2 heterojunction ozone catalyst, comprising the following steps: first, preparing a MoS2 precursor; then, dispersing the MoS2 precursor, a cobalt salt, an aluminum salt, and a precipitant in deionized water, ultrasonically dispersing and stirring the mixture, and then conducting a hydrothermal reaction; and finally, collecting the product by centrifugation, washing, drying, and calcining it to obtain the CoAl-LDO / MoS2 heterojunction ozone catalyst. The present invention synthesizes a CoAl-LDO / MoS2 heterojunction ozone catalyst by utilizing a hydrothermal reaction and a chemical in situ growth technique under mild conditions.

[0008] The specific steps for preparing the MoS2 precursor are: dispersing the molybdate and sulfur source in deionized water, ultrasonically dispersing and stirring, and then conducting a hydrothermal reaction; collecting the product by centrifugation, washing, and drying to obtain the MoS2 precursor. The formation of MoS2 is ensured by controlling the amount of molybdenum salt and sulfur source.

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

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

[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; and the precipitant is one or more of urea, sodium hydroxide, ammonia water and ammonium fluoride.

[0012] A MoS2 precursor, cobalt salt, aluminum salt, and precipitant were dispersed in deionized water. The MoS2 concentration ranged from 1.1 to 5.5 g / L, the cobalt salt concentration ranged from 0.09 to 0.21 mol / L, the aluminum salt concentration ranged from 0.03 to 0.07 mol / L, and the precipitant concentration ranged from 0.4 to 1.8 mol / L. By controlling the amount of precipitant, the integrity and thickness of the CoAl-LDO sheet structure were adjusted, ultimately affecting the contact interface between the CoAl-LDO and MoS2 species in the CoAl-LDO / MoS2 heterojunction ozone catalyst.

[0013] The molar concentration ratio of cobalt salt to aluminum salt is 1:0.2-0.6. 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, achieving uniform distribution of Al and Co at the atomic level.

[0014] The ultrasonic dispersion time is 10-15 minutes; the stirring time is 0.25-1 hour, which can ensure that the raw materials are evenly dispersed and fully contacted in the solvent, which is conducive to the subsequent hydrothermal reaction and avoids 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 that the product is fully dried while maintaining a stable state; the hydrothermal reaction temperature is 90-120°C, and the time is 8-12 hours; during calcination, the temperature is increased to 400-600°C at 2-10°C / min and maintained for 2-3 hours, and the atmosphere of 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 is to catalyze the oxidation and degradation of 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 to the antibiotic wastewater is 0.2-0.8 g / L. The ozone concentration of the catalytic ozone oxidation 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 antibiotic wastewater, stirred under dark conditions, and after reaching adsorption equilibrium, a catalytic ozone oxidation reaction is carried out under ozone conditions to complete the degradation treatment of antibiotic pollutants.

[0017] The present invention optimizes the surface distribution and loading of CoAl-LDO and MoS2 by controlling the mass ratio of CoAl-LDO and MoS2 to 1:0.1~0.5, thereby forming a more uniform and dense heterojunction structure, which is conducive to the formation of pore structure and the construction of built-in electric field, promotes the accessibility of active sites and electron transfer efficiency, and ultimately improves the catalytic ozone oxidation efficiency. The present invention can ensure that the raw materials promote crystal growth in the reactor based on the high temperature and high pressure driving force by controlling the hydrothermal reaction temperature and time. In addition, the interfacial bonding 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, the hydroxide precursor of CoAl-LDO can be ensured to be completely transformed, and the pore structure of the CoAl-LDO / MoS2 heterojunction ozone catalyst can be further optimized by interlayer anion decomposition and water molecule overflow. CoAl-LDO is a layered double metal hydroxide.

[0018] Specifically, the preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst comprises the following steps:

[0019] (1) Molybdate and sulfur source are dispersed in deionized water and mixed so that the concentration of molybdate is 0.016mol / L~0.112mol / L, the concentration of sulfur source is 0.224mol / L~0.448mol / L, and the ratio of Mo atoms to S atoms is 1:2~4. Ultrasonic dispersion is performed for 10-15 minutes, followed by magnetic stirring for 0.25-1 hour until uniform, to form a precursor solution; the precursor solution is transferred to a hydrothermal reactor and subjected to hydrothermal reaction in an oven at 160-220°C for 16-24 hours. The product is separated and recovered in a centrifuge at 4000-8000rpm, washed repeatedly with deionized water and alcohol three times, and then dried in an oven at 40-80°C to constant weight to obtain a MoS2 precursor;

[0020] (2) MoS2 precursor, cobalt salt, aluminum salt and precipitant are dispersed in deionized water and mixed so that the MoS2 precursor is 1.1g / L~5.5g / L, the cobalt salt concentration is 0.09-0.21mol / L, the aluminum salt concentration is 0.03-0.07mol / L, the precipitant concentration is 0.4-1.8mol / L, and the molar concentration ratio is cobalt salt: aluminum salt 1:0.2~0.6. Ultrasonic dispersion is carried out for 10-15min and magnetic stirring is carried out for 0.25-1h until uniform to form a precursor. solution; the precursor solution was transferred to a hydrothermal kettle and hydrothermally reacted at 90-120°C in an oven for 8-12 hours, the product was separated and recovered in a centrifuge at 4000-8000 rpm, repeatedly washed with deionized water and alcohol for 3 times, and then dried in an oven at 40-80°C to constant weight; the dried product was heated to 400-600°C at 2-10°C / min in a tubular furnace under nitrogen atmosphere and maintained for 2-3 hours to obtain a CoAl-LDO / MoS2 heterojunction ozone catalyst.

[0021] This invention synthesizes a CoAl-LDO / MoS2 heterojunction ozone catalyst using a hydrothermal reaction and chemical in situ growth under mild conditions. Specifically, a certain amount of molybdate and thiourea are dispersed in deionized water and subjected to a hydrothermal reaction under specific conditions to produce MoS2. Subsequently, a certain amount of the prepared MoS2, a cobalt salt, an aluminum salt, and a precipitant are dispersed in deionized water and subjected to a hydrothermal reaction under specific conditions. The product is calcined under an inert atmosphere to form a compact heterojunction structure, resulting in the CoAl-LDO / MoS2 heterojunction ozone catalyst.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst of the present invention is simple to operate, has mild reaction conditions, and is low in cost. The obtained ozone catalyst has a good degradation effect on antibiotics, providing a new solution for the treatment of industrial antibiotic wastewater and has broad application prospects.

[0024] (2) The CoAl-LDO / MoS2 heterojunction ozone catalyst prepared by the method of the present invention has a difference in work function between CoAl-LDO and MoS2. CoAl-LDO acts as a p-type semiconductor and MoS2 acts as an n-type semiconductor. When the two form a contact interface, a built-in electric field is formed at the interface, in which electrons are transferred from MoS2 to CoAl-LDO. This built-in electric field promotes the redox cycle of the transition metal Co ions in CoAl-LDO and ultimately achieves the regeneration of oxygen vacancies. MoS2, as an electron-deficient center, spontaneously captures electrons in organic pollutants, achieving dynamic regeneration of oxygen vacancies during the catalytic ozone oxidation reaction. Compared with artificially reducing the average oxidation state of the transition metal and increasing the oxygen vacancy content during preparation, it can achieve long-term stability and availability of the ozone catalyst.

[0025] (3) The CoAl-LDO / MoS2 heterojunction ozone catalyst prepared by the present invention is applied to the degradation of antibiotics in sewage, and has good universality. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the SEM image of the CoAl-LDO / MoS2 heterojunction ozone catalyst obtained in Example 1.

[0027] Figure 2 TEM image of the CoAl-LDO / MoS2 heterojunction ozone catalyst obtained in Example 1.

[0028] Figure 3 The catalysts prepared in Examples 1-5 and Comparative Examples 1-6 are used in the degradation of antibiotics in sewage, and the absorbance of the pollutant solution changes with illumination time.

[0029] Figure 4 The graphs show the changes in the degradation concentrations of tetracycline hydrochloride, levofloxacin, norfloxacin and oxytetracycline hydrochloride in sewage over time for the catalyst prepared in Example 1.

[0030] Figure 5 This is a graph showing the degradation activity of the catalyst prepared in Example 1 on tetracycline hydrochloride in sewage after 10 cycles of use. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to specific embodiments.

[0032] The raw materials and additives used in the following examples and comparative examples are all commercially available products.

[0033] Example 1

[0034] The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst comprises the following steps:

[0035] (1) (NH4)6Mo7O 24 4H2O and CH4N2S are dispersed in deionized water and mixed to make (NH4)6Mo7O 24 4H2O is 0.016 mol / L, CH4N2S is 0.224 mol / L, ultrasonically dispersed for 15 minutes, and then magnetically stirred for 1 hour until uniform to form a precursor solution; the precursor solution is transferred to a hydrothermal kettle and hydrothermally reacted in an oven at 200°C for 20 hours. The product is separated and recovered in a centrifuge at 6000 rpm, repeatedly washed with deionized water and alcohol three times, and then dried in an oven at 60°C to constant weight to obtain a MoS2 precursor;

[0036] (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 1.10 g / L, Co(NO3)2·6H2O 0.12 mol / L, Al(NO3)3·9H2O 0.04 mol / L, CO(NH2)2 1.70 mol / L, and ultrasonically dispersed for 15 min, and then magnetically stirred for 1 h until uniform to form a precursor solution; The precursor solution was transferred to a hydrothermal reactor and hydrothermally reacted at 100°C in an oven for 10 hours. 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 nitrogen atmosphere at a rate of 5°C / min to 500°C and maintained for 2 hours to obtain a CoAl-LDO / MoS2 heterojunction ozone catalyst with a mass ratio of CoAl-LDO and MoS2 of 1:0.1.

[0037] The SEM image of the prepared CoAl-LDO / MoS2 heterojunction ozone catalyst is shown in Figure 1 As shown by Figure 1 The CoAl-LDO / MoS2 heterojunction ozone catalyst exhibits a micro-flower structure formed by the accumulation of regularly stacked flakes. The flakes have a large aspect ratio, resulting in a large surface area and ample reactive sites for the reactants (ozone and organic pollutants). This micro-flower structure provides pathways for the reaction of ozone and organic pollutants within the catalyst, promoting contact between the reactants due to confinement.

[0038] The TEM image of the prepared CoAl-LDO / MoS2 heterojunction ozone catalyst is shown in Figure 2 As shown by Figure 2It can be seen that the microflower structure of the CoAl-LDO / MoS2 heterojunction ozone catalyst is formed by the curved nanoflower structure provided by MoS2 and the flat sheet structure provided by CoAl-LDO. Because CoAl-LDO has a positive charge and MoS2 has a negative charge, the two form a close contact due to electrostatic adsorption, which significantly promotes electron transfer in the heterojunction catalyst material.

[0039] Example 2

[0040] The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst comprises the following steps:

[0041] (1) (NH4)6Mo7O 24 4H2O and CH4N2S are dispersed in deionized water and mixed to make (NH4)6Mo7O 24 4H2O is 0.016 mol / L, CH4N2S is 0.448 mol / L, ultrasonically dispersed for 15 minutes, and then magnetically stirred for 1 hour until uniform to form a precursor solution; the precursor solution is transferred to a hydrothermal kettle and hydrothermally reacted in an oven at 160°C for 24 hours. The product is separated and recovered in a centrifuge at 4000 rpm, repeatedly washed with deionized water and alcohol three times, and then dried in an oven at 40°C to constant weight to obtain a MoS2 precursor;

[0042] (2) MoS2 precursor, Co(NO3)2·6H2O, Al(NO3)3·9H2O and NaOH were dispersed in deionized water and mixed to make the MoS2 precursor 5.50 g / L, Co(NO3)2·6H2O 0.21 mol / L, Al(NO3)3·9H2O 0.07 mol / L and NaOH 1.70 mol / L. After ultrasonic dispersion for 15 min, magnetic stirring was performed for 1 h until uniform to form a precursor solution. The precursor solution was transferred to a hydrothermal reactor and hydrothermally reacted in an oven at 90 °C for 12 h. The product was separated and recovered in a centrifuge at 4000 rpm, washed repeatedly with deionized water and alcohol three times, and then dried in an oven at 40 °C to constant weight. The dried product was heated to 400 °C at 2 °C / min in a tube furnace under nitrogen atmosphere and maintained for 3 h to obtain a CoAl-LDO / MoS2 heterojunction ozone catalyst. A CoAl-LDO / MoS2 heterojunction ozone catalyst was obtained, in which the mass ratio of CoAl-LDO to MoS2 was 1:0.3.

[0043] Example 3

[0044] The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst comprises the following steps:

[0045] (1) Na2MoO4·2H2O and C2H5NS were dispersed in deionized water and mixed to make Na2MoO4·2H2O 0.112 mol / L and C2H5NS 0.224 mol / L. After ultrasonic dispersion for 15 min, magnetic stirring was performed for 0.25 h until uniform to form a precursor solution. The precursor solution was transferred to a hydrothermal reactor and hydrothermally reacted in an oven at 220°C for 16 h. The product was separated and recovered in a centrifuge at 8000 rpm, washed repeatedly with deionized water and alcohol three times, and then dried in an oven at 80°C to constant weight to obtain a MoS2 precursor.

[0046] (2) MoS2 precursor, CoCl2·6H2O, AlCl3·6H2O and NH3·H2O were dispersed in deionized water and mixed to make the MoS2 precursor 5.50g / L, CoCl2·6H2O 0.09mol / L, AlCl3·6H2O 0.03mol / L, and NH3·H2O 0.80mol / L. Ultrasonic dispersion was performed for 15min and magnetic stirring was performed for 0.25h until uniform to form a precursor solution. The liquid was transferred to a hydrothermal kettle and hydrothermally reacted at 120°C in an oven for 8 hours. The product was separated and recovered in a centrifuge at 8000 rpm, washed repeatedly with deionized water and alcohol three times, and then dried in an oven at 80°C to constant weight. The dried product was heated to 600°C at 10°C / min in a tubular furnace under argon atmosphere and maintained for 2 hours to obtain a CoAl-LDO / MoS2 heterojunction ozone catalyst with a mass ratio of CoAl-LDO to MoS2 of 1:0.5.

[0047] Example 4

[0048] The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst comprises the following steps:

[0049] (1) Na2MoO4·2H2O and Na2S were dispersed in deionized water and mixed to make Na2MoO4·2H2O 0.112 mol / L and Na2S 0.224 mol / L. After ultrasonic dispersion for 10 min, magnetic stirring was performed for 1 h until uniformity was achieved to form a precursor solution. The precursor solution was transferred to a hydrothermal reactor and subjected to hydrothermal reaction in an oven at 200°C for 20 h. The product was separated and recovered in a centrifuge at 6000 rpm. The product was washed repeatedly with deionized water and alcohol for 3 times and then dried in an oven at 60°C to constant weight to obtain a MoS2 precursor.

[0050] (2) MoS2 precursor, CoSO4·7H2O, Al2(SO4)3·16H2O, CO(NH2)2 and NH4F were dispersed in deionized water and mixed to make the MoS2 precursor 1.10g / L, CoSO4·7H2O 0.09mol / L, Al2(SO4)3·16H2O 0.054mol / L, CO(NH2)2 1.60mol / L, NH4F 0.20mol / L, and ultrasonically dispersed for 10min and magnetically stirred for 1h until uniform. The precursor solution was transferred to a hydrothermal reactor and hydrothermally reacted at 100°C in an oven for 10 hours. The product was separated and recovered in a centrifuge at 6000 rpm, washed repeatedly with deionized water and alcohol for three times, and then dried in an oven at 60°C to constant weight. The dried product was heated to 500°C at 5°C / min in a tube furnace under argon atmosphere and maintained for 2 hours to obtain a CoAl-LDO / MoS2 heterojunction ozone catalyst with a mass ratio of CoAl-LDO to MoS2 of 1:0.1.

[0051] Example 5

[0052] The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst comprises the following steps:

[0053] (1) (NH4)6Mo7O 24 4H2O and CH4N2S are dispersed in deionized water and mixed to make (NH4)6Mo7O 24 4H2O is 0.016 mol / L, CH4N2S is 0.224 mol / L, ultrasonically dispersed for 15 minutes, and then magnetically stirred for 1 hour until uniform to form a precursor solution; the precursor solution is transferred to a hydrothermal kettle and hydrothermally reacted in an oven at 200°C for 20 hours. The product is separated and recovered in a centrifuge at 6000 rpm, repeatedly washed with deionized water and alcohol three times, and then dried in an oven at 60°C to constant weight to obtain a MoS2 precursor;

[0054] (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 1.10 g / L, Co(NO3)2·6H2O 0.21 mol / L, Al(NO3)3·9H2O 0.042 mol / L, CO(NH2)2 1.70 mol / L. Ultrasonic dispersion was performed for 15 min and magnetic stirring was performed for 1 h until uniform to form a precursor solution. ; The precursor solution was transferred to a hydrothermal kettle and hydrothermally reacted at 100°C in an oven for 10 hours. 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 heated to 500°C at 5°C / min in a tubular furnace under nitrogen atmosphere and maintained for 2 hours to obtain a CoAl-LDO / MoS2 heterojunction ozone catalyst with a mass ratio of CoAl-LDO and MoS2 of 1:0.1.

[0055] Comparative Example 1

[0056] 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 step (2) of Example 1.

[0057] Comparative Example 2

[0058] 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 step (1) of Example 1.

[0059] Comparative Example 3

[0060] 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 those in Example 1.

[0061] Comparative Example 4

[0062] The difference between Comparative Example 4 and Example 1 is that the Co(NO3)2·6H2O in step (2) is removed, and the other preparations are exactly the same as those in Example 1.

[0063] Comparative Example 5

[0064] The difference between Comparative Example 5 and Example 1 is that the concentration of MoS2 precursor in step (2) is replaced with 10 g / L, and the other preparations are exactly the same as those in Example 1.

[0065] Comparative Example 6

[0066] 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 those in Example 1.

[0067] Experiment 1: The specific surface area, pore diameter and pore volume of the catalysts prepared in the above examples and comparative examples are shown in Table 1.

[0068] Table 1 Specific surface area, pore size and pore volume of the catalyst

[0069]

[0070] Experiment 2: In order to explore 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 tetracycline hydrochloride concentration of 300 mg / L. The addition ratio of each group of catalysts was 0.6 g / L, and the mixture was stirred at 1000 rpm for uniform mixing. Stir for 30 minutes in the dark to reach adsorption and desorption equilibrium. The catalytic ozone oxidation 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. Take 3 mL of degraded solution at specific time intervals, centrifuge it thoroughly, and then take the supernatant. After filtering with a 0.22 μm filter head, use an ultraviolet-visible spectrophotometer to measure the absorbance of the solution at the characteristic wavelength of the pollutant, and record the change in the absorbance of the pollutant solution with the illumination time. The test results are as follows: Figure 3 shown.

[0071] From the above, it can be seen that compared with the ozone catalyst obtained in the comparative example, the degradation rate of tetracycline hydrochloride by the CoAl-LDO / MoS2 heterojunction ozone catalyst is significantly higher, reaching 80.39% after catalytic ozone oxidation degradation for 10 minutes. This is because:

[0072] (1) Compared with pure CoAl-LDO, the CoAl-LDO / MoS2 heterojunction ozone catalyst contains more low-valent cobalt species due to the presence of the interfacial electric field, and therefore has a higher content of active sites (oxygen vacancies); (2) Pure MoS2 itself does not have catalytic ozone oxidation activity; (3) Compared with CoO and Al2O3, CoAl-LDO, as a typical solid solution, 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 does not improve the performance of the CoAl-LDO / MoS2 heterojunction ozone catalyst, because the reduction in the composite amount of CoAl-LDO will lead to a decrease in the exposure of the active sites (oxygen vacancies) it can provide; (5) When the calcination temperature is too high, the CoAl-LDO component will lose its "structural memory effect" and it will be difficult to maintain its layered structure in pollutant-containing wastewater, resulting in a decrease in its adsorption performance, and ultimately a decrease in the opportunity for the catalyst to contact with pollutants, resulting in a decrease in its performance.

[0073] The above results show that the CoAl-LDO / MoS2 heterojunction ozone catalyst prepared in the present invention exhibits excellent performance in the degradation of tetracycline antibiotics, with a fast degradation rate and high degradation rate, and has potential application value in environmental pollution control.

[0074] 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 using the method of Experiment 2. The results are as follows: Figure 4 shown.

[0075] 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.

[0076] Experiment 4: In order to demonstrate the long-term stability of the CoAl-LDO / MoS2 heterojunction ozone catalyst of the present invention, its cyclic stability was evaluated by a system circulation 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. 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 10 times. The results are shown in FIG. Figure 5 shown.

[0077] 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 always remained 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. An application of a CoAl-LDO / MoS2 heterojunction ozone catalyst, characterized by: Used for catalytic ozone oxidation and degradation of antibiotic pollutants in water; The preparation method of the CoAl-LDO / MoS2 heterojunction ozone catalyst comprises the following steps: first, preparing a MoS2 precursor; then, dispersing the MoS2 precursor, cobalt salt, aluminum salt and precipitant into deionized water for ultrasonic dispersion and stirring, and then performing a hydrothermal reaction; finally, collecting the product by centrifugation, washing, drying and calcining to obtain the CoAl-LDO / MoS2 heterojunction ozone catalyst; the ultrasonic dispersion time is 10-15 minutes; the stirring time is 0.25-1 hour; the centrifugal speed is 4000-8000 rpm; the drying temperature is 40-80°C; the hydrothermal reaction temperature is 90-120°C and the time is 8-12 hours; during calcination, the temperature is increased to 400-600°C at 2-10°C / min and maintained for 2-3 hours, and the atmosphere of the calcination process is nitrogen or argon; 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; and the precipitant is one or more of urea, sodium hydroxide, ammonia water and ammonium fluoride.

2. The use of the CoAl-LDO / MoS2 heterojunction ozone catalyst according to claim 1, characterized in that: The specific steps for preparing the MoS2 precursor are: dispersing molybdate and sulfur source in deionized water for ultrasonic dispersion and stirring, and then performing a hydrothermal reaction; collecting the product by centrifugation, washing, and drying to obtain the MoS2 precursor.

3. The use 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 the sulfur source are calculated as Mo and S, respectively, with a molar ratio of 1:2 to 4.

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

5. The use of the CoAl-LDO / MoS2 heterojunction ozone catalyst according to claim 1, characterized in that: The MoS2 precursor, cobalt salt, aluminum salt and precipitant are dispersed in deionized water, with the MoS2 concentration being 1.1-5.5 g / L, the cobalt salt concentration being 0.09-0.21 mol / L, the aluminum salt concentration being 0.03-0.07 mol / L, and the precipitant concentration being 0.4-1.8 mol / L.

6. The use of the CoAl-LDO / MoS2 heterojunction ozone catalyst according to claim 5, characterized in that: The molar concentration ratio of the cobalt salt to the aluminum salt is 1:0.2~0.

6.

7. The use of the CoAl-LDO / MoS2 heterojunction ozone catalyst according to claim 1, characterized in that: The mass ratio of CoAl-LDO and MoS2 is 1:0.1~0.5.

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