Ti3C2-based cobalt single-atom two-dimensional material rich in titanium vacancies, preparation method thereof and application

Abstract

The present invention provides a titanium vacancy-rich Ti3C2-based cobalt single-atom two-dimensional material, a preparation method thereof, and an application thereof. The present invention uses an etching-exfoliation-reduction coupling method to prepare a peroxymonosulfate (PMS) activator of two-dimensional Ti3C2-based cobalt single atoms, creating abundant titanium vacancies without destroying the original layered structure of Ti3C2, and enabling the uniform distribution and high exposure of single-atom cobalt to obtain excellent catalytic activity. This two-dimensional material can induce 1 the generation of O2, and activate multiple oxidation mechanisms to rapidly degrade refractory organic pollutants in water media, and can resist the interference of high-concentration and various inorganic anions. Its unique two-dimensional layered structure can effectively bind the toxic Co 2+ leached from the material to reduce the risk of secondary water pollution. At the same time, its excellent stability can enable the catalytic material to be recycled multiple times, reducing the operating cost and showing great application potential in the field of water pollution treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of water pollution control of environmental functional materials, and in particular to a Ti3C2-based cobalt single-atom two-dimensional material rich in titanium vacancies, and a preparation method and application thereof. Background Art

[0002] The presence of organic micropollutants (OMPs) in the water environment is an important environmental issue facing the world today. OMPs are a class of chemicals that include personal care products, endocrine disruptors, and antibiotics. They are generally characterized by low concentration, difficulty in degradation, persistence, and bioaccumulation. OMPs are widely available and cannot be completely removed in traditional water treatment processes, which may have potential negative impacts on ecosystems and human health. Oxidation pathways are often used in wastewater treatment processes, and peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) have been widely studied in the field of water pollution control. PMS-AOPs can produce highly active free radicals (SO4 ·- and ·OH) and highly selective non-radicals ( 1 O2, high-valent metals and metal-PMS complexes), thereby achieving the mineralization and oxidation process of OMPs. However, in actual water bodies, when inorganic anions (such as Cl - 、SO4 2- 、NO3 - When PMS coexists with target pollutants, it will consume highly active free radicals and inhibit the degradation of pollutants, while reducing the utilization efficiency of PMS and may produce more toxic byproducts. 1 O2-mediated non-radical PMS-AOPs have the advantages of long half-life, strong selectivity and strong anti-interference ability, and are considered to be a promising candidate to replace free radicals (SO4 ·- and ·OH) as the dominant oxidation process. However, in traditional catalytic materials, the activation PMS process generates 1 O2 has low selectivity and is accompanied by problems such as metal ion dissolution and increased water chromaticity. Therefore, in the field of water pollution control, it is urgent to develop new catalysts to increase the dominant active substances in the process of activating PMS. 1 Selective generation of O2 and ensuring no new environmental issues are introduced while treating wastewater containing OMPs.

[0003] In single-atom catalysts (SACs), metal atoms exist entirely in an atomically dispersed manner at 100% on the support, thereby achieving maximum exposure of active sites and forming a unique electronic structure, showing great potential in activating PMS to generate 1 O2. Usually, SACs are based on carbon or heteroatom-doped carbon and are prepared by pyrolysis. After undergoing high-temperature processes, the loaded metal atoms tend to agglomerate, thereby affecting the catalytic activity of SACs. In addition, high-temperature treatment often requires a large amount of energy, which easily results in high material synthesis costs and is not conducive to environmental safety. Summary of the Invention

[0004] The object of the present invention is to provide a titanium vacancy-rich Ti3C2-based cobalt single-atom two-dimensional material, its preparation method and application to solve the problems of atomic agglomeration in single-atom catalysts, 1 poor O2 selectivity and incompatibility between catalytic activity and structural stability.

[0005] Aiming at the problems of insufficient ability of domestic traditional water treatment technologies to remove OMPs, low activity and poor stability of catalytic materials in actual water bodies, the preparation method independently developed by the present invention successfully anchors single-atom Co on the Ti3C2 support (as shown in Figure 2 c), and prepares the Co / SA-Ti3C2 material (SA means single atom). This preparation method not only reduces the problem of atomic agglomeration in SACs, but also balances the co-enhanced barrier between catalytic activity and structural stability. Compared with traditional single-atom catalytic materials, the Co / SA-Ti3C2 prepared by this method has better effects in treating refractory organic micro-pollutants in water bodies, and its manufacturing and operation costs are lower.

[0006] A preparation method of a titanium vacancy-rich two-dimensional Ti3C2-based cobalt single-atom catalytic material is as follows:

[0007] (1) Add 4 g of LiF to a polytetrafluoroethylene beaker containing 60 mL of concentrated hydrochloric acid solution, mechanically stir and control the rotation speed at 650 rpm. After complete dissolution, slowly add 2 g of MAX powder and stir in a water bath for 24 h;

[0008] (2) After removing the white floating layer in the mixed solution, centrifuge and wash the above solution until the pH of the supernatant is close to neutral, and collect the solid precipitate;

[0009] (3) Transfer the above solid precipitate to a screw-cap reagent bottle, continuously shake until a dark green viscous substance can be suspended on the inner wall of the reagent bottle, fill with nitrogen and store at low temperature;

[0010] (4) Disperse the dark green viscous substance obtained in step (3) in distilled water to prepare an aqueous solution with a concentration of 1 mg / mL. Add 10 mL of aqueous NaBH4 solution, mix and stir at a rotation speed of 650 rpm for 30 min, then perform ice bath ultrasonic treatment for 1 h. Then, centrifuge and freeze-dry the treated solution to collect the solid powder.

[0011] (5) Disperse the solid powder obtained in step (4) in distilled water to prepare a 500 mL aqueous solution. Slowly add 22.88 mL of Co(NO3)2·6H2O solution under stirring conditions, magnetically stir for 30 min, continuously perform ultrasonic treatment for 1 h, then centrifuge, wash, and freeze-dry for 24 h to collect the solid powder, which is a two-dimensional Ti3C2-based cobalt single-atom catalytic material rich in titanium vacancies, denoted as Co / SA-Ti3C2.

[0012] Preferably, the MAX in step (1) is Ti3AlC2 powder, and the water bath temperature is 35 °C.

[0013] Preferably, the centrifugation speed in step (2) is controlled at 3500 rpm, and each centrifugation treatment is for 10 min. Distilled water is used for washing, and the number of washing times is 7 times.

[0014] Preferably, distilled water is used to transfer the solid in step (3). Mechanical shaking for 1 h combined with manual shaking for 1 h is required, and the low-temperature storage condition is set at 4 °C.

[0015] Preferably, the concentration of the aqueous NaBH4 solution in step (4) is 10 mg / mL, the centrifugation speed is controlled at 8000 rpm, the centrifugation treatment time is 10 min, the freeze-drying time is 24 h, and the ultrasonic condition is an ice bath atmosphere created by circulating chilled water.

[0016] Preferably, the concentration of the solid aqueous solution in step (5) is 1 mg / mL, and the concentration of the Co(NO3)2·6H2O aqueous solution is 1 mg / mL.

[0017] Preferably, the stirring speed in step (5) is 650 rpm, and the ultrasonic condition is an ice bath atmosphere created by circulating chilled water.

[0018] Preferably, the centrifugation speed in step (5) is controlled at 10000 rpm, and each centrifugation treatment is for 10 min. Distilled water is used for washing, and the number of washing times is 2 times.

[0019] A two-dimensional Ti3C2-based cobalt single-atom catalytic material rich in titanium vacancies is prepared by the above method. Among them, cobalt is atomically dispersed on the Ti3C2 substrate, showing an obvious two-dimensional layered structure, and the loading amount of cobalt single atoms is 1.64 wt%.

[0020] A method for activating peroxymonosulfate (PMS) by a two-dimensional Ti3C2-based cobalt single-atom catalytic material rich in titanium vacancies to degrade organic micropollutants (OMPs) as described above. The preparation method developed in the present invention not only makes up for the technical defects of atomic agglomeration and poor O2 selectivity in single-atom catalysts, but also solves the problem of incompatibility between catalytic activity and structural stability. Activate PMS to degrade various OMPs in water at a relatively low operating cost, and the reaction steps are as follows: 1 Under normal temperature and pressure conditions, add Co / SA-Ti3C2 and PMS to the aqueous solution containing OMPs, and make the reaction occur under magnetic stirring.

[0021] Preferably, the reaction is carried out in a glass conical flask, the magnetic stirring rate used is 650 rpm, and the reaction time is 20 min.

[0022] Preferably, the concentration of the OMPs is 3 mg / L.

[0023] Preferably, the dosing concentration of Co / SA-Ti3C2 is 25 mg / L.

[0024] Preferably, the dosing concentration of PMS is 50 mg / L.

[0025] Preferably, the OMPs include ranitidine (RAN), rhodamine B (RhB), methyl orange (MO), methylene blue (MB), norfloxacin (NFX), ciprofloxacin (CIP), tetracycline hydrochloride (TC), bisphenol A (BPA), and carbamazepine (CBZ).

[0026]

[0027] The present invention uses a coupling method of etching-exfoliation-reduction to prepare a peroxymonosulfate (PMS) activator of two-dimensional Ti3C2-based cobalt single atoms. Without destroying the original layered structure of Ti3C2, a rich number of titanium vacancies are created, and the single-atom cobalt is evenly distributed and highly exposed to obtain excellent catalytic activity. By introducing a rich number of titanium vacancies, the surface charge transfer efficiency of the Ti3C2 layered structure is improved, enabling it to maintain long-term catalytic activity. Its unique two-dimensional layered structure can effectively bind the toxic Co leached from the material 2+ to reduce the risk of secondary water pollution. In addition, the Ti3C2-based cobalt single-atom two-dimensional material can induce 1 the generation of O2 and stimulate multiple oxidation mechanisms to rapidly degrade refractory organic micropollutants in the water medium, and can resist the interference of high-concentration and various inorganic anions, showing great application potential in the field of water pollution control with the advantages of environmental friendliness and low cost.

[0028] Compared with traditional technologies, the advantages and effects of the present invention are as follows:

[0029] ​(1) The method for preparing Co / SA-Ti3C2 in the present invention does not require a high-temperature process, reducing energy consumption and avoiding the problems of high material synthesis cost and environmental safety hazards.

[0030] (2) The method for preparing Co / SA-Ti3C2 in the present invention retains the original layered structure of Ti3C2, avoiding the agglomeration problem of single-atom cobalt and forming highly dispersed catalytic active centers.

[0031] (3) The Co / SA-Ti3C2 activation material prepared in the present invention has high structural stability, can resist high-concentration inorganic anions, and effectively binds the toxic Co leached from the material 2+ to avoid secondary pollution to the water environment.

[0032] (4) The Co / SA-Ti3C2 activation material prepared in the present invention can induce 1 the generation of O2 and activate multiple oxidation mechanisms to rapidly degrade refractory organic micro-pollutants in the water medium.

[0033] (5) The Co / SA-Ti3C2 activation material prepared in the present invention has low synthesis cost, simple required equipment, and is suitable for large-scale industrial production.

[0034] (6) In the process of activating PMS with the Co / SA-Ti3C2 activation material prepared in the present invention, no additional energy input (such as light, electricity, and heat) is required, reducing the operating cost. Moreover, the process flow is simple, the operability is strong, the activation time is short, the performance is stable, and the material input is small, having broad practical application prospects. Description of the Drawings

[0035] Figure 1 It is the X-ray crystal diffraction pattern (XRD) of the two-dimensional Ti3C2-based cobalt single-atom catalytic material Co / SA-Ti3C2 rich in titanium vacancies prepared in Example 1.

[0036] Figure 2 Among them, (a) and (b) are the scanning electron microscope images (SEM) of the two-dimensional Ti3C2-based cobalt single-atom catalytic material (Co / SA-Ti3C2) rich in titanium vacancies prepared in Example 1 at different magnifications; (c) and (d) are the scanning transmission electron microscope images (STEM); (e), (f), (g), and (h) are the X-ray energy dispersion diagrams (EDS) of oxygen, cobalt, carbon, and titanium elements, respectively.

[0037] Figure 3 It is the EPR spectrum for detecting reactive oxygen species in the reaction system using DMPO as a scavenger in Example 2.

[0038] Figure 4For the kinetic comparison of the present invention with different advanced oxidation technologies on the market for removing RAN in Example 5. Detailed implementation mode

[0039] To make the objectives, technologies, and advantages of the present invention clearer, the following provides a detailed description in combination with the accompanying drawings and specific embodiments. The embodiments are only for illustrating the present invention and do not limit the present invention.

[0040] The raw materials used in the present invention are all conventional commercially available products.

[0041] Example 1

[0042] This example compares the effects of Co / SA-Ti3C2-activated PMS on the oxidative degradation of different OMPs in the aqueous environment, including ranitidine (RAN), rhodamine B (RhB), methyl orange (MO), methylene blue (MB), norfloxacin (NFX), ciprofloxacin (CIP), tetracycline hydrochloride (TC), bisphenol A (BPA), and carbamazepine (CBZ).

[0043] (1) Preparation of the Co / SA-Ti3C2 catalytic material in the present invention: Add 4 g of LiF to a polytetrafluoroethylene beaker containing 60 mL of HCl (9 mol / L) solution, mechanically stir and control the rotation speed at 650 rpm, stir evenly. After complete dissolution, slowly add 2 g of Ti3AlC2 powder, and perform water bath stirring at 35 °C for 24 h for sufficient etching. After the etched solution removes the floating white layer first, centrifuge and wash it 7 times with distilled water at 3500 rpm for 10 min until the pH of the supernatant is close to neutral. Transfer the solid precipitate to a screw-cap reagent bottle with distilled water, and shake it mechanically for 1 h and manually for 1 h until a dark green viscous substance can be suspended on the inner wall of the reagent bottle. Then, configure it into a 500 mL aqueous solution (1 mg / mL), add 10 mL of 10 mg / mL NaBH4 aqueous solution, mix and stir at 650 rpm for 30 min, and then perform ice bath ultrasonic treatment (ice bath atmosphere made by circulating chilled water) for 1 h. Centrifuge the treated solution at 8000 rpm for 10 min and freeze-dry it for 24 h to collect the solid powder. Prepare the above solid powder into a 500 mL aqueous solution (1 mg / mL), ultrasonically dissolve it for 30 minutes, slowly add 22.88 mL of Co(NO3)2·6H2O solution (1 mg / mL) to the solution, magnetically stir at 650 rpm for 30 min, perform ice bath ultrasonic treatment for 1 h, control the centrifugation speed at 10000 rpm, and the centrifugation treatment time at 10 min. After centrifuging and washing 2 times with distilled water, freeze-dry it for 24 h to collect the solid powder, which is the two-dimensional Ti3C2-based cobalt single-atom catalytic material rich in titanium vacancies, marked as Co / SA-Ti3C2.

[0044] The XRD, SEM / STEM-EDS diagrams of the prepared Co / SA-Ti3C2 are shown in Figure 1 and 2 respectively. It can be observed from the SEM / STEM-EDS diagrams that Co / SA-Ti3C2 exhibits an obvious lamellar structure and the elements are evenly distributed on its surface. Moreover, it can be clearly seen from Figure 2 (c) that there are a large number of Ti vacancies in the material, and Co is anchored on the Ti3C2 substrate in the form of single atoms.

[0045] (2) Prepare an aqueous RAN solution with a concentration of 3 mg / L for later use.

[0046] (3) Add 200 mL of the prepared RAN aqueous solution in (2), and adjust the pH value of the aqueous solution to neutral (pH = 7.0). Add 2.5 mg of Co / SA-Ti3C2, disperse it evenly by ultrasonic treatment, and place it in a water bath at 25 °C for temperature control. The adsorption time is 10 min until the catalytic material reaches the adsorption saturation state, then add 5.0 mg of PMS, control the rotation speed at 650 rpm under magnetic stirring conditions, sample at regular intervals, and use a UV-visible spectrophotometer for testing and analysis.

[0047] (4) Change the pollutant added to the reaction vessel from 3 mg / L of RAN to 3 mg / L of MO, and keep other conditions the same as in (3).

[0048] (5) Change the pollutant added to the reaction vessel from 3 mg / L of RAN to 3 mg / L of MB, and keep other conditions the same as in (3).

[0049] (6) Change the pollutant added to the reaction vessel from 3 mg / L of RAN to 3 mg / L of NFX, and keep other conditions the same as in (3).

[0050] (7) Change the pollutant added to the reaction vessel from 3 mg / L of RAN to 3 mg / L of CIP, and keep other conditions the same as in (3).

[0051] (8) Change the pollutant added to the reaction vessel from 3 mg / L of RAN to 3 mg / L of TC, and keep other conditions the same as in (3).

[0052] (9) Change the pollutant added to the reaction vessel from 3 mg / L of RAN to 3 mg / L of BPA, and keep other conditions the same as in (3).

[0053] Under the Co / SA-Ti3C2 and PMS system, the removal effects of different OMPs are shown in Table 1.

[0054] Table 1 Removal rates of different OMPs

[0055] organic micropollutants RAN MO MB NFX CIP TC BPA Removal rate at 16 minutes % 100％ 95.1％ 96.8％ 81.0％ 87.1％ 90.4％ 86.5％ Removal rate at 30 minutes % 100％ 100％ 100％ 100％ 100％ 100％ 100％

[0056] As can be seen from Table 1, during the 16-minute rapid catalytic oxidation reaction, the removal rates of Co / SA-Ti3C2 catalyzing and activating PMS to oxidize and degrade different organic micro-pollutants were all above 80%. When the reaction time was extended to 30 min, the removal rates of the above OMPs all reached 100%. The high efficiency of the prepared Co / SA-Ti3C2 in removing organic micro-pollutants is closely related to its highly exposed cobalt single-atom active sites, indicating that this heterogeneous oxidation process generally has the ability to oxidize and degrade organic micro-pollutants in water without selectivity.

[0057] Example 2

[0058] Example 1 confirmed that the Co / SA-Ti3C2 prepared by the present invention has excellent catalytic activity and exhibits great potential for practical applications. In this example, RAN was used as the target pollutant, and several common types of actual water bodies were selected to compare the catalytic activities of Co / SA-Ti3C2 in different water body media.

[0059] (1) The preparation method of the Co / SA-Ti3C2 catalytic material was the same as step (1) in Example 1.

[0060] (2) Different water bodies were used as media to prepare a 3 mg / L RAN aqueous solution for standby.

[0061] (3) A 250 mL stoppered conical flask was selected as the reaction vessel, 200 mL of the RAN aqueous solution prepared in (2) was added, and the pH value of the aqueous solution was adjusted to neutral (pH = 7.0). 2.5 mg of Co / SA-Ti3C2 was added, ultrasonically dispersed evenly, and placed in a water bath at 25 °C for temperature control. The adsorption time was 10 min until the catalytic material reached the adsorption saturation state, and then 5.0 mg of PMS was added. The rotation speed was controlled at 650 rpm under magnetic stirring conditions. Samples were taken at regular intervals and analyzed by a UV-visible spectrophotometer.

[0062] (4) 50 μL of the scavenger aqueous solution (DMPO / TEMP) was added, mixed evenly, sucked with a capillary tube, and then placed in the sample chamber of an EPR (Bruker EMXplus-6 / 1, Germany) after being sleeved with a quartz tube for the determination of active oxidation species, as Figure 3 shown.

[0063] In different water body environments, the degradation effects of RAN are shown in Table 2.

[0064] Table 2 Removal effects of RAN in different water body media

[0065] different water media ultrapure water tap water river water lake water effluent from secondary sedimentation tank Removal rate at 20 minutes % 100％ 100％ 100％ 67.5％ 69.1％ Removal rate at 30 minutes % 100％ 100％ 100％ 100％ 84.0％ Removal rate at 60 minutes % 100％ 100％ 100％ 100％ 100％

[0066] As can be seen from Table 2, when Co / SA-Ti3C2 prepared in the present invention uses ultrapure water, tap water, and river water as media, RAN can be removed by 100% within 20 min. By extending the reaction time, RAN using lake water and the effluent from the secondary sedimentation tank as media can also be completely removed. It is confirmed that the catalytic material prepared in the present invention has strong practicability, can adapt to different environmental water media, and can realize the catalytic activation of PMS to effectively remove target pollutants. In addition, as Figure 3 can be seen, during the oxidative degradation of RAN, the signals of DMPO-SO4 ·- , DMPO-·OH, and TEMP- 1 O2 can all be captured, indicating that the Ti3C2-based cobalt single-atom two-dimensional material can induce 1 the generation of O2 and stimulate multiple oxidation mechanisms to rapidly degrade refractory organic micropollutants in water media, showing great application potential in the field of water pollution control with the advantages of environmental friendliness and high efficiency.

[0067] Example 3

[0068] Examples 1 and 2 confirmed that Co / SA-Ti3C2 prepared in the present invention has excellent catalytic activity characteristics, but structural stability is also another key characteristic of the material. In this example, the leaching risk of metal cobalt ions in Co / SA-Ti3C2 prepared under different pH conditions (pH = 3.0, pH = 5.0, pH = 7.0, pH = 9.0, pH = 11.0) was evaluated by ICP-OES / MS technology.

[0069] (1) The preparation method of the Co / SA-Ti3C2 catalytic material is the same as step (1) in Example 1.

[0070] (2) Prepare an aqueous RAN solution with a concentration of 3 mg / L for standby.

[0071] (3) Select a 250 mL stoppered conical flask as the reaction vessel, add 200 mL of the RAN aqueous solution prepared in (2), and adjust the initial pH value of the aqueous solution to the set value (pH = 3.0, pH = 5.0, pH = 7.0, pH = 9.0, pH = 11.0). Add 2.5 mg of Co / SA-Ti3C2, disperse it evenly by ultrasonic treatment, place it in a water bath at 25 °C for temperature control. The adsorption time is 10 min until the catalytic material reaches the adsorption saturation state, then add 5.0 mg of PMS, control the rotation speed at 650 rpm under magnetic stirring conditions, sample at regular intervals, and test and analyze using ICP-OES / MS (Agilent 5110, USA).

[0072] Detect the leaching concentration of cobalt ions under different initial pH conditions, and the results are shown in Table 3.

[0073] Table 3 Leaching concentration of cobalt ions at different initial pH values

[0074] Initial pH value of solution pH = 3.0 pH = 5.0 pH = 7.0 pH = 9.0 pH = 11.0 Cobalt ion leaching concentration (mg / L) 0.06 0.05 0.03 0.02 0.01

[0075] As can be seen from Table 3, under different initial pH conditions of the solution, after the catalytic oxidation reaction of Co / SA-Ti3C2, the leaching concentration of cobalt ions is much lower than the surface water limit value, indicating that the unique two-dimensional layered structure of Co / SA-Ti3C2 prepared by the present invention and the unique coordination environment of cobalt element enhance its structural stability and can effectively bind the toxic Co leached from the material 2+ , so as to reduce the risk of secondary water pollution.

[0076] Example 4

[0077] In this example, the effects of Co / SA-Ti3C2-activated PMS oxidation degradation of RAN were determined under the conditions of the presence of different types and concentrations of inorganic anions (Cl — , SO4 2— , H2PO4 — , NO3 — and HPO4 2— ).

[0078] (1) The preparation method of the Co / SA-Ti3C2 catalytic material is the same as step (1) in Example 1.

[0079] (2) Prepare an aqueous solution of RAN with a concentration of 3 mg / L for standby.

[0080] (3) Select a 250 mL stoppered conical flask as the reaction vessel, add 200 mL of the RAN aqueous solution prepared in (2), and adjust the pH value of the aqueous solution to neutral (pH = 7.0). Add 2.5 mg of Co / SA-Ti3C2, disperse it evenly by ultrasonic wave, and place it in a water bath at 25 °C for temperature control. The adsorption time is 10 min until the catalytic material reaches the adsorption saturation state, then add 5.0 mg of PMS, add different concentrations (1 mM, 5 mM, 10 mM, and 200 mM) of NaCl, control the rotation speed at 650 rpm under magnetic stirring conditions, sample at regular intervals, and use an ultraviolet-visible spectrophotometer for test analysis.

[0081] (4) Replace NaCl with different concentrations (1 mM, 5 mM, 10 mM, and 200 mM) of Na2SO4, and keep other conditions the same as (3).

[0082] (5) Replace NaCl with different concentrations (1 mM, 5 mM, 10 mM, and 200 mM) of NaH2PO4, and keep other conditions the same as (3).

[0083] (6) Replace NaCl with NaNO3 at different concentrations (1 mM, 5 mM, 10 mM, and 200 mM), and keep other conditions the same as in (3).

[0084] (7) Replace NaCl with Na2HPO4 at different concentrations (1 mM, 5 mM, 10 mM, and 200 mM), and keep other conditions the same as in (3).

[0085] In the presence of different types of inorganic anions, the degradation effect of RAN is shown in Table 4.

[0086] Table 4 Effects of different concentrations and types of inorganic anions on the removal rate of RAN

[0087] different inorganic anion concentrations <![CDATA[Cl - > <![CDATA[SO4 2- > <![CDATA[H2PO4 - > <![CDATA[NO3 - > <![CDATA[HPO4 2- > Removal rate of RAN at 1 mM 59.3％ 78.3％ 81.0％ 78.2％ 97.8％ Removal rate of RAN at 5 mM 76.4％ 92.9％ 97.8％ 65.3％ 96.3％ Removal rate of RAN at 10 mM 84.5％ 98.7％ 98.3％ 47.8％ 94.5％ Removal rate of RAN at 200 mM 97.0％ 97.4％ 94.2％ 87.1％ 93.0％

[0088] As can be seen from Table 4, during the 20-min rapid catalytic oxidation reaction, after adding different types of inorganic anions to the Co / SA-Ti3C2 and PMS system, the target pollutant RAN still has a relatively high removal rate. In the presence of high-concentration inorganic anions, the removal rate of RAN remains above 85%, proving that the catalytic material prepared in this invention has good stability and can resist the interference of high-concentration and various types of inorganic anions.

[0089] Example 5

[0090] This example compares the efficacy of Co / SA-Ti3C2 prepared in Example 1 and different types of advanced oxidation technologies for activating PMS to oxidize and degrade RAN.

[0091] (1) The preparation method of the Co / SA-Ti3C2 catalytic material is the same as step (1) in Example 1.

[0092] (2) Prepare an aqueous solution of RAN with a concentration of 3 mg / L for later use.

[0093] (3) Select a 250-mL stoppered conical flask as the reaction vessel, add 200 mL of the RAN aqueous solution prepared in (2), and adjust the pH value of the aqueous solution to neutral (pH = 7.0). Add 2.5 mg of Co / SA-Ti3C2, disperse it evenly by ultrasonic wave, and place it in a water bath at 25°C for temperature control. The adsorption time is 10 min until the catalytic material reaches the adsorption saturation state, then add 5.0 mg of PMS, control the rotation speed at 650 rpm under magnetic stirring conditions, sample at regular intervals, and use a UV-visible spectrophotometer for test and analysis.

[0094] (4) Use the most scientific reaction kinetic formula (1) currently to calculate and compare the reaction rates (k) of different advanced oxidation technologies to evaluate the oxidation and degradation efficacy of RAN.

[0095] k = 1 / m × dC RAN / dt t (1)

[0096] where k is the reaction rate, m is the dosage of the catalyst, C RAN is the concentration of RAN, and t is the reaction time.

[0097] The comparison of the removal efficiency evaluation of RAN when different advanced oxidation technologies are used is shown in Table 5 and Figure 4 as follows.

[0098] Table 5 Comparison table of the removal efficiency evaluation of RAN when different advanced oxidation technologies are used

[0099]

[0100] From Table 5 and Figure 4 it can be seen that the reaction rate constant calculated by formula (1) can intuitively reflect the treatment efficiency of this technology. Comparing different advanced oxidation technologies on the market, the efficiency of Co / SA-Ti3C2 catalytic activation of PMS for the oxidation and degradation of RAN has obvious advantages, specifically reflected in the small dosage of materials and the significant reduction of operating costs, which can meet the current scientific and technological needs of RAN pollution control. The reaction rate constant of Co / SA-Ti3C2 prepared in this invention for the catalytic activation of PMS to oxidize and degrade RAN is 2.92 - 3550.31 times that of the advanced oxidation technologies currently used on the market, which fully shows that the Co / SA-Ti3C2 of this invention has more excellent performance and practical potential.

[0101] Example 6

[0102] This example evaluates the recycling of Co / SA-Ti3C2 catalytic activation of PMS for the oxidation and degradation of RAN.

[0103] (1) The preparation method of the Co / SA-Ti3C2 catalytic material is the same as step (1) in Example 1.

[0104] (2) Prepare an aqueous solution of RAN with a concentration of 3 mg / L for standby.

[0105] (3) Select a 250 mL stoppered conical flask as the reaction vessel, add 200 mL of the RAN aqueous solution prepared in (2), and adjust the pH value of the aqueous solution to neutral (pH = 7.0). Add 2.5 mg of Co / SA-Ti3C2, disperse it evenly by ultrasonic wave, and place it in a water bath at 25 °C for temperature control. The adsorption time is 10 min until the catalytic material reaches the adsorption saturation state, then add 5.0 mg of PMS, control the rotation speed at 650 rpm under magnetic stirring conditions, sample at regular intervals, and use an ultraviolet-visible spectrophotometer for test analysis.

[0106] (4) Filter out the Co / SA-Ti3C2 in (3) through a water-based filter membrane with a pore size of 0.22 μm, and conduct the second catalytic experiment with other conditions remaining the same as in (3).

[0107] (5) Filter out the Co / SA-Ti3C2 in (4) through a water-based filter membrane with a pore size of 0.22 μm, and conduct the third catalytic experiment with other conditions remaining the same as in (3).

[0108] (6) Filter out the Co / SA-Ti3C2 in (5) through a water-based filter membrane with a pore size of 0.22 μm, and conduct the fourth catalytic experiment with other conditions remaining the same as in (3).

[0109] (7) Filter out the Co / SA-Ti3C2 in (6) through a water-based filter membrane with a pore size of 0.22 μm, and conduct the fifth catalytic experiment with other conditions remaining the same as in (3).

[0110] (8) Filter out the Co / SA-Ti3C2 in (7) through a water-based filter membrane with a pore size of 0.22 μm, and conduct the sixth catalytic experiment with other conditions remaining the same as in (3).

[0111] (9) Filter out the Co / SA-Ti3C2 in (8) through a water-based filter membrane with a pore size of 0.22 μm, and conduct the seventh catalytic experiment with other conditions remaining the same as in (3).

[0112] (10) Filter out the Co / SA-Ti3C2 in (9) through a water-based filter membrane with a pore size of 0.22 μm, and conduct the eighth catalytic experiment with other conditions remaining the same as in (3).

[0113] (11) Filter out the Co / SA-Ti3C2 in (10) through a water-based filter membrane with a pore size of 0.22 μm, and conduct the ninth catalytic experiment with other conditions remaining the same as in (3).

[0114] (12) Filter out the Co / SA-Ti3C2 in (11) through a water-based filter membrane with a pore size of 0.22 μm, and conduct the tenth catalytic experiment with other conditions remaining the same as in (3).

[0115] For the catalytic material Co / SA-Ti3C2 prepared by the present invention, the recycling situation of activating PMS to oxidize and degrade the target pollutant RAN after 10 times is shown in Table 6.

[0116] Table 6 Recycling situation of Co / SA-Ti3C2 for degrading RAN

[0117]

[0118]

[0119] As can be seen from Table 6, after 10 cycles of Co / SA-Ti3C2 catalyzing the activation of PMS for the oxidative degradation of RAN, with the increase in the number of cycles, the corresponding RAN removal rate showed an acceptable downward trend, but still remained above 75%, which has exceeded the vast majority of single-atom catalytic materials on the market. The above examples fully confirm that the Co / SA-Ti3C2 prepared by the present invention has excellent catalytic stability, can be reused continuously for multiple times, and shows significant commercial value.

[0120] In summary, the two-dimensional Ti3C2-based cobalt single-atom catalytic material (Co / SA-Ti3C2) rich in titanium vacancy structural defects synthesized by the present invention can activate PMS to generate 1 active substances mainly composed of O2, and the degradation efficiency of OMPs in water can reach more than 80% within a short time at room temperature, and it has strong resistance to various inorganic anions. In addition, the leaching amount of cobalt ions in this catalytic material is extremely low, it has excellent structural stability, can be recycled continuously for multiple times without causing secondary pollution to the water environment, showing broad application prospects of Co / SA-Ti3C2 in the field of water pollution control.

Claims

1. A preparation method of a titanium vacancy-rich Ti3C2-based cobalt single-atom two-dimensional material, characterized in that, It includes the following steps: (1) Add LiF and hydrochloric acid solution into a polytetrafluoroethylene beaker, stir evenly. After complete dissolution, add Ti3AlC2 powder, stir in a water bath, and etch fully; (2) Centrifuge and wash the etched solution until the pH of the supernatant is neutral, and collect the solid precipitate; (3) Transfer the above solid precipitate to a reagent bottle, and continuously shake until a dark green viscous substance can hang on the inner wall of the reagent bottle; (4) Disperse the above dark green viscous substance in water, add an aqueous solution of NaBH4, stir, then perform ice bath ultrasonic treatment, and then centrifuge and freeze-dry the treated solution to collect the solid powder; (5) Disperse the above solid powder in water, add an aqueous solution of Co(NO3)2·6H2O, stir, then perform ice bath ultrasonic treatment, and then centrifuge and freeze-dry the treated solution to collect the solid powder, thus obtaining a Ti3C2-based cobalt single-atom two-dimensional material rich in titanium vacancies; In step (4), the concentration of the aqueous solution of NaBH4 is 10 mg / mL, the stirring speed is 650 rpm, the centrifugation speed is controlled at 8000 rpm, the centrifugation time is 10 min, and the freeze-drying time is 24 h; In step (5), the concentration of the aqueous solution of Co(NO3)2·6H2O is 1 mg / mL, the stirring speed is 650 rpm, the centrifugation speed is controlled at 10000 rpm, and each centrifugation treatment is 10 min. Distilled water is used for washing, and the number of washing times is 2 times.

2. The preparation method of the titanium vacancy-rich Ti3C2-based cobalt single-atom two-dimensional material according to claim 1, wherein, In step (1), the stirring in the water bath is specifically: stir in a water bath at a temperature of 35°C for 24 hours.

3. The preparation method of the titanium vacancy-rich Ti3C2-based cobalt single-atom two-dimensional material according to claim 1, characterized in that, In step (2), the centrifugation speed is controlled at 3500 rpm, and each centrifugation treatment is 10 min. Distilled water is used for washing, and the number of washing times is 7 times.

4. The preparation method of the titanium vacancy-rich Ti3C2-based cobalt single-atom two-dimensional material according to claim 1, characterized in that, In step (3), the shaking is carried out by mechanical shaking for 1 h combined with manual shaking for 1 h.

5. The Ti3C2-based cobalt single-atom two-dimensional material rich in titanium vacancies prepared by the method according to any one of claims 1 to 4.

6. The Ti3C2-based cobalt single-atom two-dimensional material rich in titanium vacancies according to claim 5, characterized in that, Cobalt is atomically dispersed on the Ti3C2 substrate, presenting a two-dimensional layered structure, and the loading amount of cobalt single atoms is 1.64 wt%.

7. Application of the Ti3C2-based cobalt single-atom two-dimensional material rich in titanium vacancies according to claim 5 or 6 as a catalyst for activating PMS to oxidize and degrade OMPs.

8. The application according to claim 7, characterized in that, The OMPs include ranitidine, rhodamine B, methyl orange, methylene blue, norfloxacin, ciprofloxacin, tetracycline hydrochloride, bisphenol A and carbamazepine.

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