Preparation method of 3D tungsten carbide promoter and application of the 3D tungsten carbide promoter in catalyzing fenton reaction

Abstract

The application discloses a preparation method and application of a 3D tungsten carbide assistant catalyst, and belongs to the technical field of water treatment. The application uses powder tungsten carbide as an assistant catalyst, diatomite plate as a base, and synthesizes the 3D tungsten carbide assistant catalyst through a simple two-step impregnation method.The prepared assistant catalyst can effectively promote the circulation rate of Fe 3+ / Fe 2+ , and the assistant catalytic Fenton system can achieve more than 75% degradation effect on organic matters in water under the condition of adding 0.4mM H2O2 and 25uM FeSO4.7H2O, and the system does not produce iron mud.The degradation rate of the prepared assistant catalyst on norfloxacin is still higher than 80% after 24 times of reuse, and the leaching rate of tungsten ions is less than 0.022mg / L.Even if placed at room temperature for 4 months, the assistant catalytic activity of the prepared assistant catalyst remains unchanged.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method and application of a 3D tungsten carbide cocatalyst and belongs to the technical field of water treatment. BACKGROUND

[0002] In recent years, the cocatalytic Fenton technology using transition metal sulfides (MoS2, WS2, etc.) as cocatalysts has attracted widespread attention due to its advantages such as promoting Fe 3+ / Fe 2+ cycle, reducing the generation of iron sludge, improving the utilization rate of H2O2, and efficiently degrading refractory organic matter in water. For example, a patent with the publication number CN113731448A synthesizes MoS2 by a simple solvothermal method in one step to construct a MoS2 / Fenton system. The patent describes that MoS2 can effectively promote the cycling rate of Fe 3+ / Fe 2+ , and under the conditions of adding only 0.1 mmol of H2O2 and 1 mg / L of FeSO4, the system has a degradation rate of 73% or more for rhodamine B, p-chlorophenol, tetracycline, and / or diclofenac sodium in water. A patent with the publication number CN113003699A describes that WS2 acts as a cocatalyst to improve the Fe 3+ / Fe 2+ cycle, constructs a WS2 / Fe 2+ / peroxysulfate (peroxymonosulfate potassium, peroxymonosulfate sodium, and / or peroxymonosulfate ammonium) system, and further more efficiently activates peroxysulfate to generate active oxygen substances such as sulfate radicals and hydroxyl radicals to degrade methyl orange, rhodamine B, p-acetamidophenol, thymine, and bisphenol A in water. However, the formation of secondary pollutants H2S often accompanies these cocatalysts during use. Therefore, the development of more green and environmentally friendly cocatalysts to replace metal sulfides has attracted the attention of researchers. For example, in 2023, Tang Shoufeng's team from Yanshan University used molybdenum carbide (β-Mo2C) as a cocatalyst in a persulfate (PDS) / Fe 3+ system to degrade dexamethasone (DXM), and found that the proposed PDS / Fe 3+ / β-Mo2C can degrade more than 90% of DXM in a wide pH range (3.4-9.4), and no H2S is generated during the reaction process (doi.org / 10.1021 / acsestwater.2c00609). Wang Ping's team from Central South University of Forestry and Technology introduced tungsten carbide (WC) into a Fenton-like process of persulfate (PMS) / Fe 2+ , and found that the tetracycline hydrochloride (TC) degradation efficiency of WC / Fe 2+ / PMS was 90.4% within 18 min, which was higher than that of Fe 2+PMS was 39.9%, and the kinetic constant of the Fenton-like system with the catalyst was 3.6 times that of Fe 2+ The molybdenum carbide and tungsten carbide catalysts reported in the above-mentioned literatures, although can overcome the inherent defect of H2S produced in the process of metal sulfide catalyzed Fenton reaction, but their powder form has been greatly limited in the application of catalysts.

[0003] Preparation of supported catalysts is one of the important technologies to solve the application of powder catalysts. For example, the patent with publication number CN115106112A uses a three-dimensional porous sponge as a carrier and nitrogen-doped graphene aerogel as a binder for powder cobalt sulfide to prepare a 3D cobalt sulfide catalyst (SCG) to reduce the loss of powder cobalt sulfide. Wang Chongchen et al. used polyvinyl butyral (PVB) as a binder and fixed powder MIL-88A(Fe) on polyurethane sponge by a simple immersion method to prepare a three-dimensional MIL-88A(Fe)@sponge catalyst with good stability (doi.org / 10.1016 / j.cclet.2022.108029). The patent with publication number CN115591587A uses a heteropoly acid (tungsten silicate or tungsten phosphate) as a binder and successfully prepares a 3D molybdenum disulfide hydrophilic sponge by a simple immersion method by adding sponge to a mixed solution containing heteropoly acid and molybdenum disulfide.

[0004] However, the reported three-dimensional catalysts all use sponge as the substrate, which is easy to be compressed and aggregated, deformed and damaged after long-term use. In order to overcome the above-mentioned defects, the present invention selects a commercial porous diatomite plate which is firm, cheap, light in weight and resistant to high temperature as a substrate for loading powder tungsten carbide catalyst to prepare a three-dimensional porous structure of tungsten carbide catalyst (DW) macroscopic body for constructing a DW catalyzed Fenton system. Under the condition of pH 3-5.5, only by adding not more than 0.4 mM of H2O2 and not more than 25 μM of FeSO4·7H2O, the DW / Fenton system can achieve more than 75% degradation rate of 100 mL 10 mg / L of residual phenol, p-chlorophenol, p-nitrophenol, diclofenac, sulfadiazine, enrofloxacin, levofloxacin, norfloxacin, bisphenol A, rhodamine b, methylene blue, terephthalic acid, congo red and / or methyl orange in water, and the system does not produce iron sludge and H2S. SUMMARY

[0005] The present invention aims to provide a simple, stable in acidic water, good mechanical strength, low cost method for preparing a 3D tungsten carbide catalyst and a method for applying the catalyst in Fenton reaction.

[0006] The innovation of the present application is that the present application prepares 3D tungsten carbide cocatalyst (DW) by simple two-step impregnation method, and constructs DW cocatalytic Fenton system. At pH 3-5.5, only by adding not more than 0.4 mM of H2O2 and 25 μM of FeSO4·7H2O, the system can achieve more than 75% degradation rate of 100 mL 10 mg / L of residual phenol, p-chlorophenol, p-nitrophenol, diclofenac, sulfadiazine, enrofloxacin, levofloxacin, norfloxacin, bisphenol A, rhodamine b, methylene blue, terephthalic acid, congo red and / or methyl orange in water, and the system does not produce iron mud and H2S during the reaction process. The preparation process of DW is simple and conducive to large-scale preparation. In addition, the cocatalytic activity of DW can be regenerated by simple impregnation method. After 24 times of repeated use (regeneration 2 times), DW can still achieve more than 80% degradation rate of fluoroquinolone antibiotic norfloxacin, and the maximum leaching concentration of tungsten ions is less than 0.022 mg / L. In addition, the cocatalyst has good stability, and after being placed for 4 months, the removal rate of DW / Fenton to norfloxacin is still higher than 90%.

[0007] The key technical problem solved by the present application is to prepare a 3D tungsten carbide cocatalyst (DW) which is stable in acidic water, convenient to reuse, low in price and can be mass produced, and use it in Fenton system to accelerate the cycle of Fe 3+ / Fe 2 + and improve the degradation efficiency of organic pollutants.

[0008] Another technical problem solved by the present application is to construct DW cocatalytic Fenton system, only by adding 0.4 mM of H2O2 and 25 μM of FeSO4·7H2O, the system can achieve more than 75% degradation rate of 100 mL 10 mg / L of residual phenol, p-chlorophenol, p-nitrophenol, diclofenac, sulfadiazine, enrofloxacin, levofloxacin, norfloxacin, bisphenol A, rhodamine b, methylene blue, terephthalic acid, congo red and / or methyl orange in water.

[0009] The present application also solves the technical problem that the DW cocatalytic Fenton system constructed does not produce iron mud and H2S during the reaction process.

[0010] The technical solution of the present application is as follows.

[0011] The detailed preparation method of a 3D tungsten carbide cocatalyst is as follows:

[0012] (1) Cut diatomite plate into blocks with length, width and height of 1.0-2.5 cm, 1.0-2.5 cm and 0.5-3 cm respectively. The diatomite blocks are sequentially immersed in beakers containing ethanol and deionized water, each step is treated by ultrasonic, and then dried in a forced air drying oven to obtain pretreated diatomite blocks;

[0013] (2) Put the pretreated diatomite blocks and dopamine hydrochloride into 80-200 mL Tris-HCl buffer solution. After standing overnight, wash several times with deionized water, and then dry in a 60°C oven to obtain diatomite block substrates coated with polydopamine film;

[0014] (3) Immerse the diatomite block substrates coated with polydopamine film obtained in step (2) into a mixed solution containing binder and WC in ethanol or methanol or acetone and water, stir for 1 h, and then dry at 60°C to obtain 3D tungsten carbide assistant catalyst.

[0015] In the above method, in step (1), the mass of the diatomite block is 1.5-5 g; the diatomite block is purchased from Changbai Yin, and the specific surface area, average pore size, porosity and bulk density of the diatomite block are 112.47 m 2 / g, 6.85 μm, 62.39% and 0.7208 g / cm 3 , respectively; the mass fraction of ethanol is 50%-100%; the ultrasonic treatment time of each step is 5-30 min; the drying temperature is 60-100°C, and the drying time is 2-4 h.

[0016] In the above method, in step (2), the number of diatomite blocks is 1-30, the concentration of dopamine hydrochloride is 0.5-4 g / L, the concentration of Tris-HCl buffer solution is 5-20 mM, and the pH value of Tris-HCl buffer solution is 7.5-10;

[0017] In the above method, in step (3), the number of diatomite block substrates coated with polydopamine film is 1-50; the binder is one or more of polyvinyl butyral, polyvinyl formal, polypropylene alcohol, polypropylene glycol ether, polyvinyl ether, polyhydroxypropyl methyl cellulose and / or polyvinyl ketone; the concentration of the binder is 0.5-3 g / L; the mass of WC is 50-500 mg; the mass fraction of ethanol or methanol or acetone is 50%-100%; the volume ratio of ethanol or methanol or acetone to water is (4-1):1; the stirring time is 1-5 h, and the rotation speed is 100-250 r / min.

[0018] The 3D tungsten carbide assistant catalyst prepared by the above method is a macroscopic three-dimensional structure with high mechanical strength.

[0019] The surface exposed reduced tungsten species (W 0 and W 4+ ) of the prepared catalyst promoter can rapidly reduce Fe 3+ to Fe 2+ , stimulate the generation of sufficient ·OH to achieve efficient degradation of organic pollutants in water.

[0020] The application also provides application of the catalyst promoter Fenton system constructed by the 3D tungsten carbide catalyst promoter in degradation of residual toxic and refractory organic matter in water, such as phenol / halogenated phenol / p-nitrophenol, broad-spectrum disinfectant (triclosan, triclocarban, etc.), analgesic (diclofenac), antibiotic and dye.

[0021] The application also provides application of the catalyst promoter Fenton system constructed by the 3D tungsten carbide catalyst promoter in degradation of organic pollutants in water, comprising the following steps:

[0022] (1) uniformly dispersing the 3D tungsten carbide catalyst promoter and Fe 2+ in water containing organic pollutants;

[0023] (2) adjusting the pH value of the mixed system to 3-6 by using hydrochloric acid or sodium hydroxide;

[0024] (3) stirring the mixed system for 20-30 min, the stirring speed is 100-300 r / min, after adsorption equilibrium is reached, 30% H2O2 by mass fraction is added to start the reaction, and the reaction time is 10-30 min.

[0025] In the above method, the number of the 3D tungsten carbide catalyst promoter is 1-5; the concentration of the Fe 2+ is 12.5-100 μM; the organic pollutants include phenol, p-chlorophenol, p-nitrophenol, diclofenac, sulfadiazine, enrofloxacin, levofloxacin, norfloxacin, bisphenol A, rhodamine b, methylene blue, terephthalic acid, congo red and / or methyl orange; and the concentration of the H2O2 is 0.01-0.08 mM.

[0026] Compared with the prior art, the application has the beneficial effects that the application provides a 3D tungsten carbide catalyst promoter, a preparation method and application thereof.

[0027] (1) the 3D tungsten carbide catalyst promoter has a macro three-dimensional structure and a simple preparation process, reduces the operation cost and improves the economic benefit.

[0028] (2) The catalytic activity of the catalyst can be regenerated by impregnation to promote the continuous and efficient degradation of pollutants. The degradation efficiency of the DW catalytic Fenton system for norfloxacin is still higher than 80% after the catalyst is reused 24 times (regenerated twice), and the leaching rate of tungsten ions is less than 0.022 mg / L. In addition, the 3D tungsten carbide catalyst has good stability, and after being placed for 4 months, the removal rate of norfloxacin in the DW catalytic Fenton system is still higher than 90%.

[0029] (3) By adding 3D tungsten carbide as a catalyst, the recycling rate of Fe 3+ / Fe 2 + in the DW catalytic Fenton system can be effectively promoted, so that the concentration of Fe 2+ in the system is maintained at a high level. When the pH of the DW catalytic Fenton system is 3-5.5, only 0.4 mM H2O2 and 25 μM Fe 2+ need to be added to achieve a degradation rate of 95% for 100 mL of 10 mg / L norfloxacin, thereby minimizing the addition of Fe 2+ and H2O2.

[0030] (4) The system does not produce iron sludge and H2S.

[0031] (5) Powder catalysts such as transition metal sulfides (molybdenum disulfide, tungsten disulfide and / or cobalt disulfide, etc.), transition metal carbides (Mo2C, W2C and / or MoC, etc.) and transition metal borides (MoB, CoB, FeB and / or WB) can be used to prepare macro-structured catalysts by the method. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 XRD pattern of the 3D tungsten carbide catalyst prepared in Example 1.

[0033] Figure 2 Scanning electron microscope test results of the 3D tungsten carbide catalyst prepared in Example 1.

[0034] Figure 3 XPS pattern of the 3D cobalt sulfide catalyst prepared in Example 1.

[0035] Figure 4 Effect of the number of times the 3D tungsten carbide catalyst is reused on the degradation of norfloxacin.

[0036] Figure 5 Photo of the 3D tungsten carbide catalyst loaded with a 2 Kg weight (the embedded photo is the actual photo of the 3D tungsten carbide catalyst without the weight). DETAILED DESCRIPTION

[0037] The application will be described in further detail below with reference to the drawings and specific embodiments.

[0038] Example 1

[0039] A method for preparing a 3D tungsten carbide cocatalyst (DW) comprises the following steps:

[0040] (1) Cut diatomite plate substrate into blocks with length, width and height of 1.5 cm, 1 cm and 2 cm respectively. Dip the block-shaped diatomite blocks into beakers containing 75% by mass ethanol and deionized water in sequence, and after ultrasonic treatment for 30 min, dry them in a blast drying oven at 100°C to obtain clean diatomite blocks;

[0041] (2) Add 30 diatomite blocks (the specific surface area, average pore size, porosity and bulk density of the diatomite blocks are 112.47 m 2 / g, 6.85 μm, 62.39% and 0.7208 g / cm 3 , respectively) and 0.5 g / L dopamine hydrochloride to 150 mL of 12 mM Tris-HCl buffer solution (pH = 10). After standing overnight, wash several times with deionized water, and then dry in a 60°C oven to obtain diatomite block substrates coated with a polydopamine film;

[0042] (3) Dip the 30 diatomite block substrates coated with a polydopamine film obtained in step (2) into 300 mL of 75% ethanol solution containing 0.5 g / L polyvinyl formal and 50 mg WC, and after stirring for 3 h (at a speed of 100 r / min), dry to obtain a 3D tungsten carbide cocatalyst.

[0043] Characterize the 3D tungsten carbide cocatalyst prepared in this example.

[0044] Figure 1 Figure 1 is an XRD spectrum of the 3D tungsten carbide cocatalyst in Example 1. The seven main sharp characteristic peaks on DW match the (001), (100), (101), (110), (111), (102) and (201) crystal planes of WC, proving that WC is successfully loaded on the block-shaped diatomite block substrate

[0045] Figure 2 Figure 2 is a scanning electron microscope (SEM) image of the 3D tungsten carbide cocatalyst prepared in Example 1. From the figure, it can be observed that the granular tungsten carbide is loaded on the diatomite block substrate

[0046] Figure 3 Figure 3 is an XPS spectrum of the 3D tungsten carbide cocatalyst prepared in Example 1. From the figure, it can be analyzed that there are reduced tungsten species (W0 and W 4+ ) can reduce Fe 3+ to Fe 2+ .

[0047] Example 2

[0048] Three pieces of the catalyst prepared in Example 1 were added into 100 mL of a norfloxacin solution with a concentration of 10 mg / L. The reaction was started after 25 μM of Fe 2+ and 0.4 mM of H2O2 were added into the solution. After 16 min, the degradation rate of norfloxacin in the presence of the catalyst was 95%. In the absence of the catalyst, the reaction was started after 25 μM of Fe 2+ and 0.4 mM of H2O2 were added into the solution. After 16 min, the degradation rate of norfloxacin in the presence of the homogeneous Fenton system was 41%. Eight mg of powder WS2 or MoS2 were added into 100 mL of a norfloxacin solution with a concentration of 10 mg / L. The reaction was started after 25 μM of Fe 2+ and 0.4 mM of H2O2 were added into the solution. After 16 min, the degradation rates of norfloxacin in the presence of the powder WS2 or MoS2 catalyst were 93% and 60%, respectively. That is, the addition of the catalyst DW into the homogeneous Fenton system can effectively promote the recycling rate of Fe 3+ / Fe 2+ in the reaction system, and the catalytic performance of DW is superior to that of the typical metal sulfide catalyst (powder WS2 or MoS2).

[0049] Example 3

[0050] Effect of the number of times of reuse of the 3D tungsten carbide catalyst on the removal of norfloxacin:

[0051] The 3D tungsten carbide prepared in Example 1 was used as a catalyst to construct a catalytic Fenton system. The effect of the number of times of reuse of the catalyst on the degradation rate of norfloxacin was investigated under the conditions that the dosages of FeSO4•7H2O and H2O2 were 25 μM and 0.4 mM, respectively, and the pH value of the solution was not adjusted (5.5). The catalytic activity can be regenerated through the process of step (3) in Example 1. As shown in Table 2, the degradation rate of 100 mL of a norfloxacin solution with a concentration of 10 mg / L was maintained at more than 80% within 16 min after the catalyst was reused for 24 times. The leaching rate of tungsten ions in the 3D tungsten carbide catalyst was less than 0.022 mg / L, which indicates that the catalyst has excellent stability. Figure 4

[0052] Example 4

[0053] ​A preparation method of a 3D tungsten carbide promoter (DW) comprises the following steps:

[0054] (1) Cut diatomite plate material into blocks with length, width and height of 1.5 cm. Dip the diatomite blocks into beakers containing anhydrous ethanol and deionized water in sequence, dry in a blast drying oven at 100°C after ultrasonic treatment for 15 min, and obtain clean diatomite blocks;

[0055] (2) Put 30 diatomite blocks after cleaning and 2 g / L dopamine hydrochloride into 200 mL 15 mM Tris-HCl buffer solution (pH=8). After standing overnight, wash several times with deionized water, and dry in a 60°C oven to obtain diatomite block substrates coated with a polydopamine film;

[0056] (3) Dip 30 diatomite plate substrates coated with a polydopamine film obtained in step (2) into 300 mL 75% ethanol solution containing 1 g / L polyhydroxypropyl methylcellulose and 100 mg WC, stir for 2 h (at a speed of 150 r / min), and dry to obtain a 3D tungsten carbide promoter.

[0057] Example 5

[0058] A preparation method of a 3D tungsten carbide promoter (DW) comprises the following steps:

[0059] (1) Cut diatomite plate substrates into blocks with length, width and height of 2 cm. Dip the blocky diatomite blocks into beakers containing anhydrous ethanol and deionized water in sequence, dry in a blast drying oven at 100°C after ultrasonic treatment for 30 min, and obtain clean diatomite blocks;

[0060] (2) Put 30 diatomite blocks after cleaning and 1 g / L dopamine hydrochloride into 150 mL 15 mM Tris-HCl buffer solution (pH=9). After standing overnight, wash several times with deionized water, and dry in a 60°C oven to obtain diatomite block substrates coated with a polydopamine film;

[0061] (3) Dip 30 diatomite plate substrates coated with a polydopamine film obtained in step (2) into 300 mL anhydrous ethanol solution containing 1 g / L polyvinyl butyral and 100 mg WC, stir for 2 h (at a speed of 100 r / min), and dry to obtain a 3D tungsten carbide promoter.

[0062] Example 6

[0063] Two pieces of 3D tungsten carbide co-catalyst synthesized in Example 5 were added to 100 mL of a 10 mg / L phenol solution, the pH value of the solution was adjusted to 5 with 1 mol / L HCl, and the reaction was started after 25 μM FeSO4•7H2O and 0.4 mM H2O2 were added to the solution. After 16 min of reaction, the degradation rate of the co-catalytic Fenton system to phenol was 90%.

[0064] Example 7

[0065] Two pieces of 3D tungsten carbide co-catalyst synthesized in Example 5 were added to 100 mL of a 10 mg / L p-chlorophenol solution, the pH value of the solution was adjusted to 5 with 1 mol / L HCl, and the reaction was started after 25 μM FeSO4•7H2O and 0.4 mM H2O2 were added to the solution. After 16 min of reaction, the degradation rate of the co-catalytic Fenton system to p-chlorophenol was 93%.

[0066] Example 8

[0067] Two pieces of 3D tungsten carbide co-catalyst synthesized in Example 5 were added to 100 mL of a 10 mg / L p-nitrophenol solution, the pH value of the solution was adjusted to 5 with 1 mol / L HCl, and the reaction was started after 25 μM FeSO4•7H2O and 0.4 mM H2O2 were added to the solution. After 16 min of reaction, the degradation rate of the co-catalytic Fenton system to p-nitrophenol was 78%.

[0068] Example 9

[0069] Two pieces of 3D tungsten carbide co-catalyst synthesized in Example 5 were added to 100 mL of a 10 mg / L diclofenac solution, the pH value of the solution was adjusted to 5 with 1 mol / L HCl, and the reaction was started after 25 μM FeSO4•7H2O and 0.4 mM H2O2 were added to the solution. After 16 min of reaction, the degradation rate of the co-catalytic Fenton system to diclofenac was 92%.

[0070] Example 10

[0071] Two pieces of 3D tungsten carbide co-catalyst synthesized in Example 5 were added to 100 mL of a 10 mg / L sulfadiazine solution, the pH value of the solution was adjusted to 5 with 1 mol / L HCl, and the reaction was started after 25 μM FeSO4•7H2O and 0.4 mM H2O2 were added to the solution. After 16 min of reaction, the degradation rate of the co-catalytic Fenton system to sulfadiazine was 88%.

[0072] Example 11

[0073] Two pieces of 3D tungsten carbide cocatalysts synthesized in Example 1 were added to 100 mL of enrofloxacin and levofloxacin solutions with a concentration of 10 mg / L respectively, the pH value of the solution was adjusted to 5 with 1 mol / L of HC1, and the reaction was started after adding 25 μM of FeSO4·7H2O and 0.4 mM of H2O2. After 16 min of reaction, the degradation rates of enrofloxacin and levofloxacin in the cocatalytic Fenton system were 94% and 91% respectively.

[0074] Example 12

[0075] Two pieces of 3D tungsten carbide cocatalysts synthesized in Example 1 were added to 100 mL of congo red, rhodamine B, methylene blue and methyl orange solutions with a concentration of 10 mg / L respectively, the pH value of the solution was adjusted to 5 with 1 mol / L of HC1, and the reaction was started after adding 25 μM of FeSO4·7H2O and 0.4 mM of H2O2. After 16 min of reaction, the degradation rates of congo red, methylene blue, rhodamine B and methyl orange in the cocatalytic Fenton system were 96%, 94%, 90% and 87% respectively.

[0076] Example 13

[0077] Two pieces of 3D tungsten carbide cocatalysts synthesized in Example 1 were added to 100 mL of bisphenol A solutions with a concentration of 10 mg / L respectively, the pH value of the solution was adjusted to 5 with 1 mol / L of HC1, and the reaction was started after adding 25 μM of FeSO4·7H2O and 0.4 mM of H2O2. After 16 min of reaction, the degradation rate of bisphenol A in the cocatalytic Fenton system was 93%.

[0078] Example 14

[0079] Two pieces of 3D tungsten carbide cocatalysts synthesized in Example 1 were added to 100 mL of terephthalic acid solutions with a concentration of 10 mg / L respectively, the pH value of the solution was adjusted to 4 with 1 mol / L of HC1, and the reaction was started after adding 25 μM of FeSO4·7H2O and 0.4 mM of H2O2. After 16 min of reaction, the degradation rate of terephthalic acid in the cocatalytic Fenton system was 75%.

[0080] Example 15

[0081] The 3D tungsten carbide cocatalyst prepared in Example 5 was added to a 100 mL norfloxacin solution with a concentration of 10 mg / L, which was adjusted to pH 5 with 1 mol / L HCl. The reaction was started by adding 25 μM FeSO4·7H2O and 0.4 mM H2O2 to the solution. After 16 min, the degradation rates of norfloxacin in the Fenton system with the cocatalyst placed for 2, 3 and 4 months were 95%, 92% and 93%, respectively. The cocatalyst has excellent stability and can be placed for a long time.

[0082] Example 16

[0083] To study the mechanical strength of the 3D tungsten carbide cocatalyst, a 2 Kg weight was placed on the 3D tungsten carbide cocatalyst. The structure of the 3D tungsten carbide cocatalyst did not change, indicating that the 3D tungsten carbide cocatalyst has good mechanical strength. Figure 5

[0084] Example 17

[0085] The powder state cocatalysts such as transition metal sulfides (molybdenum disulfide, tungsten disulfide and / or cobalt disulfide, etc.), transition metal carbides (Mo2C, W2C and / or MoC, etc.) and transition metal borides (MoB, CoB, FeB and / or WB) can all be used to prepare macrostructure cocatalysts by the method. The detailed preparation process is as described in Example 5, except that the same mass of WC is replaced by other powder state cocatalysts (MoS2, WS2, CoS2, Mo2C, W2C, MoC, MoB, CoB, FeB and / or WB).

[0086] The above examples are preferred embodiments of the present application, but the specific embodiments of the present application are not limited to the above examples, and other changes, modifications, simplifications, etc. made by those skilled in the art without departing from the spirit and principles of the present application should be included in the patent protection scope defined by the claims of the present application.​

Claims

1. A method for preparing a 3D tungsten carbide promoter, characterized in that, The method comprises the following steps: (1) cutting diatomite plate substrate, immersing diatomite blocks into ethanol and deionized water respectively, each step being treated by ultrasonic, and then drying in a blast drying oven to obtain pretreated diatomite blocks; (2) putting the pretreated diatomite blocks and dopamine hydrochloride into 80-200 mL Tris-HCl buffer solution, standing, washing with deionized water for several times, and drying to obtain diatomite block substrate coated with polydopamine film; (3) immersing the diatomite block substrate coated with polydopamine film obtained in step (2) into a uniformly mixed ethanol or methanol or acetone and water mixed solution containing binder and WC, stirring, and drying to obtain 3D tungsten carbide assistant catalyst; the mass of WC is 50-500 mg.

2. The method of claim 1, wherein the 3D tungsten carbide promoter is prepared by the steps of: In step (1), the cutting is cutting the diatomite plate substrate into a block with length, width and height of 1.0-2.5 cm, 1.0-2.5 cm and 0.5-3 cm respectively; the mass of the diatomite block is 1.5-5 g; the specific surface area, average pore size, porosity and bulk density of the diatomite block are 112.47 m 2 / g, 6.85 μm, 62.39% and 0.7208 g / cm 3 respectively; the mass fraction of the ethanol is 50%-100%; the ultrasonic treatment time in each step is 5-30 min; the drying temperature is 60-100 ℃, and the drying time is 2-4 h.

3. The method of claim 1, wherein the 3D tungsten carbide co-catalyst is prepared by the steps of: In step (2), the diatomite blocks are 1-30; the concentration of dopamine hydrochloride is 0.5-4 g / L; the concentration of Tris-HCl buffer solution is 5-20 mM; the pH value of Tris-HCl buffer solution is 7.5-10; the drying is drying in an oven at 60-100°C; and the standing time is 6-24 h.

4. The method of claim 1, wherein the 3D tungsten carbide co-catalyst is prepared by the steps of: In step (3), the diatomite block coated with polydopamine film is 1-50; the binder is one or more of polyvinyl butyral, polyvinyl formal, polypropylene alcohol, polypropylene glycol ether, polyvinyl glycol ether, polyhydroxypropyl methyl cellulose and / or polyvinyl ketone; the concentration of the binder is 0.5-3 g / L; the mass fraction of ethanol or methanol or acetone is 50%-100%; the volume ratio of ethanol or methanol or acetone to water is (1-4):1; the stirring time is 1-5 h, and the rotating speed is 100-250 r / min; and the drying temperature is 40-80°C.

5. Application of the 3D tungsten carbide assistant catalyst prepared by the preparation method of any one of claims 1-4 in constructing an assistant Fenton system for degrading residual toxic and refractory organic matter in water, wherein the organic matter includes phenol, halogenated phenol, p-nitrophenol, broad-spectrum disinfectant, analgesic, antibiotic and dye; the broad-spectrum disinfectant includes triclosan or triclocarban; and the analgesic includes diclofenac.

6. Use according to claim 5, characterized in that, Applying 3D tungsten carbide co-catalyst DW to the DW / Fenton system, Fe 2+ Activated H₂O₂ generates ·OH radicals, which oxidize and degrade residual toxic and recalcitrant organic matter in the water. Simultaneously, Fe... 2+ Oxidized to Fe 3+ Fe 3+ W on the surface of the co-catalyst 0 and / or W 4+ Reduced to Fe 2+ This promotes Fe 2+ / Fe 3+ The cycle ensures that there is enough Fe in the system. 2+ Ensure that the amount of FeSO4·7H2O used does not exceed 25μM, so as to activate H2O2 and generate a sufficient amount of ·OH.

7. Use according to claim 5, characterized in that, The 3D tungsten carbide assistant Fenton system can minimize the dosage of H2O2, and the dosage of H2O2 is not more than 0.4 mM under the premise of ensuring high efficiency of the DW / Fenton system.

8. Use according to claim 5, characterized in that, After the 3D tungsten carbide assistant catalyst DW is repeatedly used for 24 times and regenerated for 2 times in acid water, the degradation rate of 100 mL 10 mg / L norfloxacin in water is higher than 80%, and the leaching rate of tungsten is less than 0.022 mg / L, so that the DW has good assistant catalytic performance and chemical stability; the acid is pH=3-5.

5.

9. Use according to claim 5, characterized in that, After the assistant catalyst is placed for 4 months, the degradation rate of norfloxacin by the DW / Fenton system is still higher than 90%, and the assistant catalytic activity of the assistant catalyst decays little.

10. Use according to claim 5, characterized in that, The DW / Fenton system can remove more than 75% of phenol, p-chlorophenol, p-nitrophenol, diclofenac, sulfadiazine, enrofloxacin, levofloxacin, norfloxacin, bisphenol A, rhodamine b, methylene blue, terephthalic acid, congo red and / or methyl orange in 100 mL of 10 mg / L solution under the condition of adding 0.4 mM H2O2 and 25 μM FeSO4·7H2O, and the system does not produce iron mud and H2S.

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