Application of sulfur-deficient cerium single-atom doped cobalt sulfide nanomaterials in catalytic degradation of antibiotics

Abstract

The application discloses application of a sulfur-defect-rich cerium monatomic doped cobalt sulfide nanomaterial in catalytic degradation of antibiotics. 4‑x As an electron transfer station, the sulfur vacancy defect in the nanocatalyst induces stronger electron-vibration coupling, captures and promotes the active site to induce PMS to give a high redox potential; when the antibiotic with rich electrons approaches the PMS molecule activated by the catalyst, a ternary system of electron donor-mediator-receptor is formed, electrons are directly taken from the antibiotic to induce oxidation, and the chain reaction is initiated by the breakage of the peroxide bond in the PMS molecule, so that the antibiotic is oxidatively degraded. The application can realize almost 100% removal rate of tetracycline within 10 minutes and almost 100% removal rate of sulfamethoxazole within 15 minutes.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of sewage treatment, and particularly relates to an application of a sulfur-deficient cerium monatomic atom doped cobalt sulfide nanomaterial in catalytic degradation of antibiotics. BACKGROUND

[0002] High toxicity, low degradation efficiency and easy bioaccumulation in food chain of antibiotic residues have been a big problem in the treatment of micro-polluted water bodies. Therefore, effective control of antibiotic content in micro-polluted water bodies and reasonable treatment of residual antibiotic pollution before discharge are the main preventive measures to prevent the accumulation of pollutants.

[0003] The advanced oxidation process (AOPs) based on peroxymonosulfate (PMS) is one of the most promising technologies for degrading refractory organic pollutants in water. Although PMS is considered as a strong oxidant in thermodynamics, the direct reaction kinetics between PMS and most pollutants is too slow. Therefore, developing efficient catalysts to activate PMS and produce reactive species (ROS) is the key to accelerate the oxidation of organic pollutants. In the homogeneous catalytic system, metal ions in aqueous solution can effectively react with PMS free, but there are certain limitations that hinder its practical application. As an alternative method, heterogeneous PMS activators have been widely studied. However, the spatial structure of traditional cobalt oxide particles limits the number of active sites and the efficiency of electron transfer in the catalyst, which makes the actual catalytic performance of heterogeneous catalysts in AOPs not very ideal. Therefore, it is urgent to find an efficient PMS activation method to remove antibiotics in wastewater.

[0004] The activation of PMS under the conditions of catalyst or external energy can produce oxidizing species with high redox potential, such as hydroxyl radicals (·OH) and sulfate radicals (SO4· - ). But free radicals are easily affected by solute components, inorganic ions and even pH fluctuations and are annihilated, thereby increasing the invalid consumption of oxidants. Compared with the free radical process, the non-free radical pathway has higher selectivity, higher PMS utilization rate and stronger ability to resist the interference of background anions and complex organic matter. Therefore, developing catalysts with non-free radical dominant path and promoting efficient activation of PMS has important significance for practical wastewater treatment applications. As a PMS activator, monatomic catalyst has been proved to have the potential ability to degrade pollutants through non-free radical pathway, i.e. electron transfer process (ETP). Especially, the rare earth monatomic atom composite catalyst with Co metal base is considered as an ideal choice for activating PMS to degrade pollutants due to its maximum atomic utilization efficiency and the highest reactivity of Co(II). Compared with the common Co-N4 configuration, the asymmetric coordination Co-S xThe electron density of the Co atom in the Ce configuration is increased, which can enhance the electron interaction between the Co-Ce atom and the PMS molecule, thereby promoting the activation of PMS. However, since the redox potential of ETP and the like is low, they have poor mineralization ability to pollutants. Therefore, improving the treatment efficiency of the combined oxidation process of free radicals and non-free radicals is of great significance to the application of the combined oxidation process of free radicals and non-free radicals in the treatment of refractory pollutants in wastewater. SUMMARY

[0005] In order to solve the problem of low efficiency of free radicals and non-free radicals generated by breaking the O-O bond in the prior art PMS activation process, the present application provides a sulfur-deficient cerium single-atom doped cobalt sulfide nanomaterial, a preparation method thereof and an application thereof in catalytic degradation of antibiotics, aiming to solve the problem of poor effect of the existing peroxymonosulfate-based advanced oxidation process in degrading antibiotics in water. The present application uses a simple defect induction in-situ single-atom anchoring strategy to prepare Ce single-atom doped Co3S 4-x The hollow porous nanocubes increase the contact area and improve the number of active sites, and are used for efficient activation of peroxymonosulfate (PMS), which enhances the efficient and rapid removal of antibiotics through the non-free radical electron transfer pathway and the superoxide (O2· - ) free radical pathway.

[0006] The technical scheme of the present application is as follows:

[0007] The present application aims to provide an application of a sulfur-deficient cerium single-atom doped cobalt sulfide nanomaterial in catalytic degradation of antibiotics, and also includes peroxymonosulfate.

[0008] In the embodiments of the present application, the molecular formula of the sulfur-deficient cerium single-atom doped cobalt sulfide nanomaterial is Ce-Co3S 4-x , wherein x is 1-3, and it is a porous nanocube structure.

[0009] In the embodiments of the present application, the preparation method of the sulfur-deficient cerium single-atom doped cobalt sulfide nanomaterial comprises the following steps:

[0010] Providing ZIF-67 nanocubes;

[0011] Mixing and dispersing the ZIF-67 nanocubes and a sulfuration agent in a solvent to obtain an intermediate 1 by reaction;

[0012] Heating the obtained intermediate 1 to obtain an intermediate 2;

[0013] Dispersing the obtained intermediate 2 and cerium salt in a solvent, adding a reducing agent, and reacting to obtain the product.

[0014] In the embodiment of the present application, the ZIF-67 nanocubes are prepared by dissolving a cobalt salt, 2-methylimidazole and a surfactant in a solvent.

[0015] In the embodiment of the present application, the reaction conditions for preparing the ZIF-67 nanocubes are stirring reaction, and then centrifuging to collect the product; wherein the centrifugal speed is 3000-8000 rmp, and the centrifuging time is 3-10 min.

[0016] In the embodiment of the present application, at least one or more of the following conditions are met:

[0017] The surfactant is one or more of polyvinylpyrrolidone, sodium dodecyl benzene sulfonate, triethanolamine and cetyltrimethylammonium bromide;

[0018] The cobalt salt is one or more of nitrate, sulfate and chloride;

[0019] The molar ratio of the cobalt salt, 2-methylimidazole and surfactant is (0.2-3.6):(10-28):1.

[0020] In the embodiment of the present application, the sulfuration agent is selected from one or more of thiourea, sodium sulfide, sublimed sulfur, thioacetamide or sulfur powder.

[0021] In the embodiment of the present application, the mass ratio of the ZIF-67 nanocubes and the sulfuration agent is 1:(1-3.6).

[0022] In the embodiment of the present application, the solvent is a conventional solvent in the art, such as one or more of water, ethanol and ethylene glycol, or an aqueous ethanol solution, wherein the volume ratio of water to ethanol is 1:2.

[0023] In the embodiment of the present application, the reaction conditions for preparing the reaction intermediate 1 are reaction at 20-160℃ for 1-18 h; further including separation, purification and drying; and the drying temperature is 45-70℃.

[0024] In the embodiment of the present application, the heating reaction conditions are that the purified and dried intermediate 1 is placed in an inert atmosphere, and reacted at 200-500℃ for 0.5-5 h; further including crushing the intermediate 2.

[0025] Further, the inert atmosphere refers to an atmosphere formed in a non-active gas, wherein the non-active gas refers to nitrogen and / or argon. Considering the difficulty and cost, nitrogen is preferred.

[0026] In the embodiment of the present application, the reducing agent is one or more of oxalic acid, potassium borohydride, sodium borohydride and hydrogen; and the concentration of the reducing agent is 0.1-2 mol / L.

[0027] In the embodiment of the present application, the cerium salt is selected from cerium nitrate or cerium chloride.

[0028] In the embodiment of the present application, the mixing of the intermediate 2 and the cerium salt is performed by magnetic stirring, and the stirring time is 2-12 h.

[0029] In the embodiment of the present application, the mass ratio of the sulfur-defect-rich cerium single-atom doped cobalt sulfide nanomaterial to the peroxymonosulfate is 1-15:5-25.

[0030] In the embodiment of the present application, the antibiotic includes one or more of tetracycline, sulfamethoxazole and sulfisoxazole.

[0031] Further, the antibiotic is derived from sewage, and the concentration of the antibiotic is 1-50 mg / L.

[0032] Beneficial effects: the present application is composed of Ce-Co3S 4-x nanocatalyst and peroxymonosulfate (PMS) for removing antibiotics in sewage, wherein the antibiotic is an electron donor, PMS is an electron acceptor, Ce-Co3S 4-x nanocatalyst, the sulfur vacancy defects act as an electron relay station, the defects induce stronger electron-vibration coupling, capture and promote active site-induced PMS to impart high redox potential, when the antibiotic with rich electrons approaches the PMS molecule activated by the catalyst, a ternary system of electron donor-mediator-acceptor is formed, electrons are directly taken from the antibiotic to induce oxidation, and the peroxide bond in the PMS molecule is broken to initiate a chain reaction, thereby continuously oxidizing and degrading the antibiotic through the ETP process. The composition of the present application can efficiently, stably and quickly remove multiple antibiotic pollutants in the water environment through the electron transfer process, and can achieve almost 100% removal rate of tetracycline within 10 min and almost 100% removal rate of sulfamethoxazole within 15 min. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to make the content of the present application more easily understood, the present application will be further described in detail below according to specific embodiments of the present application and in conjunction with the drawings, wherein,

[0034] Figure 1 The catalyst prepared for Example 1 and Comparative Examples 1-3 of the present application was used to remove antibiotic pollutant sulfamethoxazole (SMX) in activated PMS, and the C t / C0.

[0035] Figure 2Transient current test of the electro-oxidation reactor prepared from the cerium single-atom doped cobalt sulfide nanocatalyst with sulfur-rich defects obtained in Embodiment 1 of the present application.

[0036] Figure 3 Electrochemical impedance spectroscopy (EIS) diagram of the cerium single-atom doped cobalt sulfide nanocatalyst with sulfur-rich defects obtained in Embodiment 1 of the present application.

[0037] Figure 4 Chronoamperometry (i-t) test of the cerium single-atom doped cobalt sulfide nanocatalyst with sulfur-rich defects obtained in Embodiment 1 of the present application. DETAILED DESCRIPTION

[0038] To solve the technical problems pointed out in the background art, the present application provides an application of a cerium single-atom doped cobalt sulfide nanomaterial with sulfur-rich defects in catalytic degradation of antibiotics. To make the purpose, technical scheme and effects of the present application more clear and explicit, the present application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0039] The present application is realized by the following scheme:

[0040] The present application provides an application of a cerium single-atom doped cobalt sulfide nanomaterial with sulfur-rich defects in catalytic degradation of antibiotics, which also includes monopersulfate.

[0041] In some embodiments, the molecular formula of the cerium single-atom doped cobalt sulfide nanomaterial with sulfur-rich defects is Ce-Co3S 4-x , wherein x is 1-3; and it is a porous nanocubic structure.

[0042] The present application provides a preparation method of a Ce-Co3S 4-x nanocatalyst, which has low cost, good preparation repeatability and stability, excellent catalytic performance of the catalytic material, good reusability and environmental friendliness. - -S2 - ) and cation (Co 2+ -Ce 3+ ) two-step exchange procedures, which can in-situ anchor the transition metal cerium single atom in the cobalt sulfide nanocube catalyst with sulfur-rich vacancy defects. This unit point embedding method can effectively increase the exposure of metal active sites and activate the catalytic (redox) performance of the active sites by changing the electronic delocalization and energy distribution of the cobalt sites. Secondly, the constructed hierarchical ordered hollow porous structure can greatly improve the utilization efficiency of the catalytically active sites, enhance the mass transfer rate of the reaction substrates and catalytic products on the catalyst interface, solve the problem that the deeply buried active centers in the catalyst are difficult to participate in the catalytic reaction, and further improve the catalytic performance.

[0043] In some embodiments, the preparation method of the sulfur-deficient cerium single-atom doped cobalt sulfide nanomaterial (Ce-Co3S 4-x The preparation method of the nanocatalyst comprises the following steps:

[0044] Providing ZIF-67 nanocubes;

[0045] Mixing and dispersing the ZIF-67 nanocubes and a sulfuration agent in a solvent to obtain an intermediate 1 through reaction;

[0046] Performing calcination on the obtained intermediate 1 to obtain an intermediate 2;

[0047] Dispersing the obtained intermediate 2 and a cerium salt in a solvent, adding a reducing agent, and reacting to obtain the product.

[0048] In an embodiment of the present application, the ZIF-67 nanocubes are prepared by dissolving a cobalt salt, 2-methylimidazole, and a surfactant in a solvent, and reacting to obtain the product.

[0049] In an embodiment of the present application, the ZIF-67 nanocubes are prepared by dissolving a cobalt salt, 2-methylimidazole, and a surfactant in a solvent, and reacting to obtain the product.

[0050] In some embodiments, the stirring reaction is performed under preset temperature conditions, and the preset temperature conditions are 20-160℃, but are not limited thereto; the centrifugal speed is 1000-8000rpm, and the centrifugal time is 1-10min. In this embodiment, different sizes of nanocubes can be synthesized under different reaction temperatures, and the longer the reaction time, the smaller the particle size, and the nanocrystals are prone to agglomeration. This is because, as the reaction time increases, the particle size of the formed metal nanometer gradually decreases, which easily causes the phenomenon of agglomeration of the nanocrystals; and when the temperature increases, the reduction of the mixture and the cobalt compound occurs at the same time, which causes the separation of the formed cobalt nanocubes and cobalt nanoparticles. Therefore, by simple solvent reaction, the ZIF-67 nanocubes of different sizes with uniform growth can be prepared by selecting specific temperature and time in the dimethylimidazole system.

[0051] In some embodiments, the cobalt salt is one or more of cobalt nitrate, cobalt sulfate, and cobalt chloride, but is not limited thereto; and the concentration of the cobalt salt is 0.1mM-3mM.

[0052] In some embodiments, the surfactant is one of polyvinylpyrrolidone, sodium dodecylbenzenesulfonate, triethanolamine, and cetyltrimethylammonium bromide, but is not limited thereto.

[0053] In some embodiments, the sulfurizing agent is one of thiourea, sodium sulfide, sublimed sulfur, thioacetamide, and sulfur powder, but is not limited thereto. The amount of the sulfurizing agent is 1.0 mM-20.0 mM. In this embodiment, the crystal type of the cobalt sulfide and the hollow structure can be further controlled by controlling the amount and time of the sulfurizing agent. The O 2- -S 2- degree of ion exchange. The more the sulfurizing agent, the more oxygen is exchanged out, and according to the gradual increase in sulfur content, it can be sequentially divided into CoS, CoS2, Co3S4, and Co9S8.

[0054] In some embodiments, in the step of calcining the intermediate product in an inert atmosphere in a vacuum tube furnace, the calcination temperature is 260-500°C, and the calcination time is 1-5 h. The inert atmosphere is nitrogen, helium, or argon, and from the perspective of difficulty and cost, nitrogen is preferred. In this embodiment, the calcination temperature and time will affect the formation of the crystal and control the degree of porosity on the nanobox; too high or too low a temperature cannot obtain the expected material. The formation mechanism of the porous nanobox catalyst is attributed to the non-equilibrium shrinkage and adhesion due to a large temperature gradient during the thermal decomposition of the solid precursor. Specifically, the newly born outermost shell tries to maintain the outer diameter and resist further shrinkage, while the internal precursor shrinks urgently due to the loss of organic components at a gradually increasing temperature. That is to say, heterogeneous shrinkage occurs. The interface between the core-shell is subjected to two opposite forces: cohesive force (σco) from the inner core and adhesive force (σad) from the rigid shell. The former promotes the inward shrinkage of the inner core, and the latter prevents the inward shrinkage of the inner core. When σco<σad, the inner core shrinks outward to the pre-formed shell, thereby forming a hollow structure. When the heating temperature increases, σco exceeds σad. Therefore, the inner core shrinks inward and separates from the hard shell, forming an eggshell structure. When the heating temperature further increases, the ultrafine structure units will gather together, thereby forming a porous structure. This embodiment finds by experiment that when the calcination temperature is 260-500°C and the calcination time is 1-5 h, a porous nanobox catalyst can be prepared.

[0055] In some embodiments, the reducing agent is one or more of oxalic acid, potassium borohydride, sodium borohydride, and hydrogen, but is not limited thereto.

[0056] In some embodiments, the mass ratio of the sulfur-deficient cerium single-atom doped cobalt sulfide nanomaterial to the monopersulfate is 1-15:5-25.

[0057] The sulfur-deficient cerium single-atom anchored cobalt sulfide nanobox of the present application is Ce-Co3S 4-x (sulfur-deficient cerium single-atom anchored cobalt sulfide nanobox, which can also be denoted as Ce SAs -Co3S4-x ) nanocatalyst, the Ce-Co3S 4-x The nanocatalyst has a unique electronic structure, maximum atomic utilization efficiency, and excellent effect of selectively generating free radicals in the activation of PMS. Specifically, the formation of the Ce-Co bimetallic center after two-step ion exchange is conducive to the adsorption of PMS anions, the electronegativity of Ce is relatively low, and the electronic compensation effect between Co and sulfur ions leads to the formation of a cobalt electron-rich center. Through vacancy adsorption and reduction, PMS molecules are contacted on the surface of the catalyst and induced to activate the O-O bond to form O-Co-S v -Ce, and then *O-O is formed, and a large amount of O2· is further desorbed. - This is different from the traditional Co-based catalysts that activate PMS through a non-radical (singlet oxygen) pathway, and the present application mainly produces superoxide radicals in the form of a radical pathway. Secondly, the nanoscale cavity provides a suitable place for the catalytic reaction, fully exposes the site, strengthens mass transfer, and is conducive to improving the mutual contact of the host and the guest and the radical tandem catalysis, so that the free radicals generated by catalyzing PMS can oxidize the organic pollutants nearby.

[0058] In the present application, the degradation of antibiotic pollutants mainly follows the enhanced electron transfer path, in which the antibiotic is the electron donor, PMS is the electron acceptor, and the sulfur vacancy defect in the catalyst is the electron transfer station. The defect induces stronger electron-vibration coupling, captures and promotes the active site to induce PMS to have a high oxidation-reduction potential. When the antibiotic with rich electrons approaches the PMS molecule activated by the defect catalyst, a ternary system of electron donor-mediator-receptor is formed, which directly extracts electrons from it to induce oxidation, promotes the rupture of the peroxide bond in the PMS molecule to initiate a chain reaction, and thus oxidizes and degrades the antibiotic.

[0059] The catalyst composition provided by the present application can efficiently, stably and quickly remove multiple antibiotic pollutants in wastewater environment, such as tetracycline, sulfamethoxazole, sulfisoxazole, etc., through an electron transfer process, wherein the Ce-Co3S 4-x The nanocatalyst can activate PMS to achieve almost 100% removal rate of tetracycline within 10 min and almost 100% removal rate of sulfamethoxazole within 15 min.

[0060] In some embodiments, the Ce-Co3S 4-x The mass ratio of the nanocatalyst and peroxymonosulfate is 1-15:5-25. The present embodiment finds through experiments that when the mass ratio of the Ce-Co3S 4-x The mass ratio of the nanocatalyst and peroxymonosulfate is 1-15:5-25. The present embodiment finds through experiments that when the mass ratio of the Ce-Co3S 4-xThe nano-catalyst can fully activate peroxymonosulfate, thereby inducing PMS to give a high redox potential, and more efficiently achieving degradation and removal of antibiotics.

[0061] The application will be further explained and described below by means of specific embodiments:

[0062] Example 1

[0063] Ce-Co3S 4-x The preparation of the nano-catalyst comprises the following steps:

[0064] S1, preparation of ZIF-67 nanocubes:

[0065] First, 0.5 mM of Co(NO3)2·6H2O was dissolved in 20 mL of deionized water containing 4 mg of polyvinylpyrrolidone. Then the solution was quickly injected into 80 mL of an aqueous solution containing 28 mM 2-methylimidazole, and the mixture was stirred at 25°C for 30 min. The product was collected by centrifugation at 4000 r / min for 3 min, washed with ethanol several times, and finally dried in a vacuum oven at 60°C for 12 h to collect the product ZIF-67 nanocubes.

[0066] S2, preparation of Co3S4 hollow nanocubes:

[0067] The prepared ZIF-67 cubes and 1.3 mM thiourea were dispersed in 30 mL of ethanol, and the solution was transferred to a Teflon-lined stainless steel autoclave, which was heated in an oven at 160°C for 10 h. The precipitate was collected by centrifugation and washed with ethanol. The precipitate was annealed at 350°C in a N2 atmosphere for 2 h (3°C / min) to obtain hollow Co3S4 nanocubes.

[0068] S3, Ce-Co3S 4-x Preparation of hollow nanocubes:

[0069] Hollow Co3S4 nanocubes dispersed in 50 mL of ethanol and 0.04 mM Ce(NO3)3·6H2O were dispersed in 50 mL of ethanol and mixed well, and then stirred magnetically at 60°C for 10 h, and then sodium borohydride was added and reacted for 1 h. The obtained Ce-Co3S was collected by centrifugation 4-x , washed with ethanol several times, and dried.

[0070] Example 2

[0071] Ce-Co3S 4-x The preparation of the nano-catalyst comprises the following steps:

[0072] S1, preparation of ZIF-67 nanocubes:

[0073] Firstly, 1.3 mM of Co(N03)2*6H20 was dissolved in 20 mL of deionized water containing 8 mg of sodium dodecyl benzene sulfonate. Then the solution was quickly injected into 80 mL of aqueous solution containing 55 mM of 2-methylimidazole, and the mixture was stirred at 25 °C for 30 min. The product was collected by centrifugation at 4300 r / min for 5 min, washed with ethanol for several times, and finally dried in a vacuum oven at 60 °C for 12 h to collect the product ZIF-67 nanocubes.

[0074] S2, Preparation of Co3S4 hollow nanocubes:

[0075] The prepared ZIF-67 cubes and 3.1 mM of thioacetamide were dispersed in 30 mL of ethanol, and the solution was transferred into a Teflon-lined stainless steel autoclave and heated in an oven at 160 °C for 10 h. The precipitate was collected by centrifugation and washed with ethanol. The precipitate was annealed at 350 °C for 2 h under N2 atmosphere (3 °C / min) to obtain hollow Co3S4 nanocubes.

[0076] S3, Ce-Co3S 4-x Preparation of hollow nanocubes:

[0077] The 10 mg of hollow Co3S4 nanocubes dispersed in 50 mL of ethanol and 0.10 mM of Ce(N03)3*6H20 were dispersed in 50 mL of ethanol and mixed well, and then stirred magnetically at 60 °C for 10 h, and then sodium borohydride was added and reacted for 1 h. The obtained Ce-Co3S was collected by centrifugation 4-x , washed with ethanol for several times, and dried.

[0078] Example 3

[0079] Ce-Co3S 4-x The preparation of the nanocatalyst includes the following steps:

[0080] S1, Preparation of ZIF-67 nanocubes:

[0081] Firstly, 2.9 mM of Co(N03)2*6H20 was dissolved in 10 mL of deionized water containing 15 mg of cetyltrimethylammonium bromide. Then the solution was quickly injected into 90 mL of aqueous solution containing 70 mM of 2-methylimidazole, and the mixture was stirred at 25 °C for 30 min. The product was collected by centrifugation at 3500 r / min for 10 min, washed with ethanol for several times, and finally dried in a vacuum oven at 60 °C for 12 h to collect the product ZIF-67 nanocubes.

[0082] S2, Preparation of Co3S4 hollow nanocubes:

[0083] The prepared ZIF-67 cubes and 4.6 mM sodium sulfide were dispersed in 30 mL of ethanol, and the solution was transferred into a Teflon-lined stainless steel autoclave and heated at 160 °C for 10 h in an oven. The precipitate was collected by centrifugation and washed with ethanol. The precipitate was annealed at 350 °C for 2 h under N2 atmosphere (3 °C / min) to obtain hollow Co3S4 nanocubes.

[0084] S3, Ce-Co3S 4-x Preparation of hollow nanocubes:

[0085] The prepared ZIF-67 cubes and 4.6 mM sodium sulfide were dispersed in 30 mL of ethanol, and the solution was transferred into a Teflon-lined stainless steel autoclave and heated at 160 °C for 10 h in an oven. The precipitate was collected by centrifugation and washed with ethanol. The precipitate was annealed at 350 °C for 2 h under N2 atmosphere (3 °C / min) to obtain hollow Co3S4 nanocubes. 4-x , washed with ethanol for several times, and dried.

[0086] Comparative Example 1

[0087] Synthesis of Co3S4 hollow nanocubes

[0088] The prepared ZIF-67 cubes and 4.6 mM sodium sulfide were dispersed in 30 mL of ethanol, and the solution was transferred into a Teflon-lined stainless steel autoclave and heated at 160 °C for 10 h in an oven. The precipitate was collected by centrifugation and washed with ethanol. The precipitate was annealed at 350 °C for 2 h under N2 atmosphere (3 °C / min) to obtain hollow Co3S4 nanocubes.

[0089] Comparative Example 2

[0090] Synthesis of Co3S4 nanoparticles

[0091] The prepared ZIF-67 cubes and 4.6 mM sodium sulfide were dispersed in 30 mL of ethanol, and the solution was transferred into a Teflon-lined stainless steel autoclave and heated at 160 °C for 10 h in an oven. The precipitate was collected by centrifugation and washed with ethanol. The precipitate was annealed at 350 °C for 2 h under N2 atmosphere (3 °C / min) to obtain hollow Co3S4 nanocubes.

[0092] Comparative Example 3

[0093] Synthesis of Co3O4 nanoparticles

[0094] First, 0.888 g of sodium hydroxide was dissolved in 14 mL of deionized water, then mixed with a Co(N03)2*6H20 solution (12.8 g of salt in 30 mL of water), and finally transferred to a 80 mL Teflon-lined stainless steel autoclave. Then heated at 180 °C for 12 h. Black precipitate was obtained, washed with deionized water several times, dried at 60 °C overnight, and finally heat-treated at 550 °C for 2 h in air with a temperature rise rate of 1 °C per minute to prepare Co304 nanoparticles.

[0095] Test Example 1

[0096] Catalytic degradation test:

[0097] Catalyst activated PMS removal of pollutants experiments were carried out at 25 °C. The method of catalyst activated PMS removal of pollutants experiments is that 150 mL beaker containing 50 mL of aqueous pollutants solution, the concentration of pollutants is 10 mg / L. 3 mg of catalyst and 0.6 mM of PMS were added to the aqueous pollutants solution at 25 °C, the catalyst is the sulfur-deficient cerium single-atom doped cobalt sulfide nanobox catalyst prepared in Example 1 and the catalyst obtained in Comparative Examples 1-3, and the Fenton-like catalytic reaction was carried out under stirring conditions to ensure the uniformity of the contact between the catalyst and the organic pollutant molecules. Every time interval, 1 mL of reaction solution was taken out, diluted by one time, filtered by 0.22 μm organic filter head, and the residual pollutant concentration in the reaction solution was detected by ultraviolet spectrophotometer. And according to formula (1), the degradation efficiency of pollutants was calculated.

[0098] Formula (1): degradation efficiency (%) = (1-C t / C0) x 100%, wherein C0is the initial concentration of pollutants in water, C t is the concentration of residual pollutants in water after degradation.

[0099] Figure 1 With the common refractory micropollutant sulfamethoxazole (SMX) in water as the research object, the catalytic activity of Ce-Co3S4 catalyst to PMS was investigated. From Figure 1 the results can be seen that the hollow porous Ce-Co3S4 nanobox prepared in Example 1 shows the most outstanding catalytic activity, which can achieve 100% removal of SMX in 15 minutes. In contrast, the removal of SMX by adsorption of PMS alone can be ignored.

[0100] This test example constructs an electro-oxidation reactor, and PMS and SMX are divided into separate pools, where SMX can only be oxidized by electron transfer, Figure 2 shows that Ce-Co3S 4-xThe electro-oxidation reactor achieved higher instantaneous current (71.3 pA) and higher SMX oxidation efficiency. This result provides strong evidence that part of SMX is oxidatively degraded directly through the electron transfer pathway, Ce-Co3S 4-x effectively promotes electron transfer from SMX to PMS.

[0101] Figure 3 The contribution of electron transfer was further explored by electrochemical tests. First, the electrical conductivity (charge transfer ability) of the catalysts was evaluated by electrochemical impedance spectroscopy (EIS). In Figure 3 the Nyquist plots shown, the radius of Ce-Co3S 4-x is the smallest among the same catalysts, indicating that Ce-Co3S 4-x has a lower charge transfer resistance, thus accelerating electron transfer and promoting PMS activation. On the other hand, it indicates that Ce-Co3S 4-x / PMS*may have faster interfacial charge transfer with SMX, accelerating the rapid degradation of organic pollutants.

[0102] Figure 4 The electron transfer rate in the PMS activation process was studied by chronoamperometry. As shown in Figure 4 , the injection of PMS and SMX significantly affected the current output, confirming the electron transfer in the PMS activation process. The current of the Ce-Co3S4 electrode increased significantly after the addition of PMS, indicating that strong electron transfer occurred between PMS and the Co-Ce double atomic site. The addition of SMX caused the current to rise again, which was due to the rapid electron transfer response when the SMX molecules diffused to the catalyst surface and reacted with the interfacially activated PMS.

[0103] It should be understood that the application of the present application is not limited to the above examples, and those of ordinary skill in the art can make improvements or changes according to the above description, and all these improvements and changes shall belong to the protection scope of the appended claims of the present application.

Claims

1. The application of a sulfur-rich defective cerium single-atom-doped cobalt sulfide nanomaterial in the catalytic degradation of antibiotics, characterized in that, Add sulfur-rich defective cerium single-atom-doped cobalt sulfide nanomaterials and peroxymonosulfate to catalyze the degradation of antibiotics; The preparation method of the sulfur-rich defective cerium single-atom-doped cobalt sulfide nanomaterial includes the following steps: ZIF-67 nanocubes are available; The ZIF-67 nanocubes and the vulcanizing agent were mixed and dispersed in a solvent, and the reaction was carried out to obtain intermediate 1. The obtained intermediate 1 was calcined to obtain intermediate 2; The obtained intermediate 2 and cerium salt are dispersed in a solvent, a reducing agent is added, and the reaction is carried out to obtain the final product.

2. The application according to claim 1, characterized in that, The antibiotics include one or more of tetracycline, sulfamethoxazole, and sulfaisoxazole.

3. The application according to claim 1, characterized in that, The molecular formula of the sulfur-rich defective cerium single-atom-doped cobalt sulfide nanomaterial is Ce-Co3S. 4-x Where x is 1-3; the sulfur-rich defective cerium single-atom doped cobalt sulfide nanomaterial has a porous nanocubic structure.

4. The application according to claim 1, characterized in that, The ZIF-67 nanocubes were prepared by dissolving cobalt salt, 2-methylimidazole and surfactant in a solvent and reacting the solutions.

5. The application according to claim 4, characterized in that, The surfactant is one or more selected from polyvinylpyrrolidone, sodium dodecylbenzenesulfonate, triethanolamine, and hexadecyltrimethylammonium bromide; The cobalt salt is one or more of cobalt nitrate, cobalt sulfate, and cobalt chloride; The molar ratio of the cobalt salt, 2-methylimidazole and surfactant is (0.2-3.6):(10-28):

1.

6. The application according to claim 1, characterized in that, The vulcanizing agent is selected from one or more of thiourea, sodium sulfide, sublimed sulfur, thioacetamide, or sulfur powder.

7. The application according to claim 1, characterized in that, The reducing agent is one or more of oxalic acid, potassium borohydride, and sodium borohydride; the concentration of the reducing agent is 0.1-2 mol / L.

8. The application according to claim 1, characterized in that, The cerium salt is selected from cerium nitrate or cerium chloride.

9. The application according to claim 1, characterized in that, The mass ratio of the sulfur-rich defective cerium single-atom doped cobalt sulfide nanomaterial to peroxymonosulfate is 1-15:5-25.

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