Nickel-phosphine co-doped molybdenum disulfide composite material as well as preparation method and application thereof

Abstract

The invention discloses a nickel-phosphine co-doped molybdenum disulfide composite material as well as a preparation method and application thereof. According to the method, nickel ions and organic phosphonic acid molecules are co-doped into the structure of molybdenum disulfide, and the nickel-phosphine co-doped molybdenum disulfide composite material with high stability and catalytic performance is prepared by fully utilizing the good conductivity of molybdenum disulfide, the chemical modification function of organic phosphonic acid and the strong oxidation-reduction activity of the nickel ions. The composite material shows excellent catalytic performance in the aspect of catalytically activating peroxymonosulfate to oxidize and degrade organic pollutants, can effectively degrade the organic pollutants in wastewater, and has the advantages of mild reaction conditions, high degradation rate, high catalytic stability, high pollution resistance, high reusability and wide application prospect.

Description

Technical Field

[0001] The invention belongs to the field of nitrogen-containing organic pollutant degradation catalysts and relates to a nickel-phosphine co-doped molybdenum disulfide composite material and a preparation method and application thereof. Background Art

[0002] Nitrogen pentanion (N5 - ) Energetic materials are a type of chemical group with high energy density and high energy release efficiency. Due to their excellent performance, they have broad application potential in the fields of military propellants, aerospace fuels and high-efficiency blasting. However, the preparation process of nitrogen pentaanion energetic materials usually involves highly reactive organic chemicals and complex chemical reactions, which inevitably produce a large amount of high-concentration, toxic and harmful wastewater. These wastewaters have complex compositions and often contain nitro compounds, nitramine compounds, unreacted chemical raw materials and metal ions. These pollutants are significantly toxic to the environment and biological systems, and wastewater treatment faces great challenges.

[0003] At present, there are several technical difficulties in the treatment of wastewater from the preparation of nitrogen penta-anionic energetic materials: (1) Complex composition and difficult treatment: The wastewater contains a variety of organic pollutants, metal ions and unreacted chemical solvents. Due to the diversity of chemical structures, some pollutants form complex pollution, which is difficult to separate and treat. (2) High chemical stability and difficult degradation: Organic pollutants in wastewater, such as nitro compounds and nitramine compounds, have stable chemical bonds and strong antioxidant capacity, resulting in extremely low natural degradation and traditional biological degradation effects. In addition, toxic pollutants in wastewater will also inhibit microbial activity, making conventional activated sludge method, aerobic / anaerobic treatment and other methods difficult to work. (3) High environmental risk: During the wastewater treatment process, the partial degradation of nitro compounds and nitramine compounds may generate more toxic intermediates such as nitrites and imines. Once these products enter the water or soil, they will not only have a long-term toxic effect on the ecosystem, but may also pose a potential threat to human health through enrichment in the food chain.

[0004] In response to the above difficulties, although traditional physical adsorption, chemical oxidation and biological treatment technologies have been applied to the treatment of similar industrial wastewater, studies have shown that these methods often exhibit problems such as low degradation efficiency and high treatment costs when treating high-concentration and complex nitrogen pentaanion wastewater, which makes it difficult to meet industrial needs.

[0005] In recent years, advanced oxidation processes (AOPs) have been widely used to generate highly reactive free radicals (such as OH·, SO· -AOPs are suitable for the treatment of highly toxic and difficult-to-degrade organic wastewater, but their degradation efficiency and operating costs are highly dependent on the performance of the catalyst.

[0006] Catalysts play a vital role in AOPs, and determine the wastewater degradation efficiency and treatment effect by promoting oxidant activation and free radical generation. However, existing catalysts still have limitations in terms of stability, durability, and cost control. There is an urgent need to develop new high-efficiency, low-cost, and durable catalysts that can achieve rapid and efficient degradation of organic pollutants in high-concentration, toxic and harmful nitrogen pentaanion wastewater.

[0007] Molybdenum disulfide (MoS2) is a material with a unique layered structure. It has attracted extensive attention in the field of catalysis due to its good conductivity, high specific surface area and abundant surface active sites. In catalytic hydrogenation, dehydrogenation, oxidation and other reactions, MoS2 exhibits excellent catalytic performance. In recent years, MoS2 has gradually been used in the degradation catalysis of organic pollutants. However, due to the limitations of the surface active sites of MoS2, its catalytic efficiency in treating nitrogen pentaanion wastewater still needs to be further improved.

[0008] Nickel (Ni), as a highly active transition metal, has good electrical conductivity and electronic conductivity. The introduction of nickel doping in MoS2 can not only significantly enhance the electronic conductivity of the material, but also increase the active sites by forming a Ni-MoS2 synergistic effect, significantly improving the overall performance of the catalyst. In addition, 2-phosphono-1,2,4-tricarboxylic acid butane (PBTCA), as a functional organic phosphonate, has good chelating ability and surface modification function. At present, some scholars have used Ni-doped MoS2 to prove that it can regulate the electronic state and active sites by doping for efficient catalysis (Lv J, Sun X, Wang F, et al. Engineering Nickel Dopants in Atomically Thin Molybdenum Disulfide for Highly Efficient Nitrate Reduction to Ammonia [J]. Advanced Functional Materials, 2024, 34: 49). However, there is no report on the application of PBTCA in the oxidation treatment of nitrogen pentaanion wastewater. Summary of the invention

[0009] The purpose of the present invention is to provide a nickel-phosphine co-doped molybdenum disulfide composite material and its preparation method and application. The present invention utilizes nickel doping to provide additional active sites, and PBTCA modification further stabilizes the active sites and improves the electron transfer efficiency. The synergistic effect of the two significantly improves the performance of the catalyst in persulfate activation, thereby efficiently degrading organic pollutants, and the performance of the catalyst is stable, avoiding secondary pollution caused by the dissolution of heavy metals.

[0010] The technical solution for achieving the purpose of the present invention is as follows:

[0011] The preparation method of the nickel-phosphine co-doped molybdenum disulfide composite material comprises the following steps: firstly, a precursor solution is prepared using molybdenum salt, nickel salt and sulfur source as raw materials; then, an organic phosphonate is added dropwise to the precursor solution to allow the organic phosphine to fully react with nickel and molybdenum to form a stable complex; and then, hydrothermal reaction and high-temperature annealing are sequentially performed to further enhance the stability and conductivity of the composite material, thereby obtaining the nickel-phosphine co-doped molybdenum disulfide composite material. The method specifically comprises the following steps:

[0012] (1) adding a sulfur source to a molybdenum salt solution having a concentration of 0.1 to 0.5 M according to a molar ratio of molybdenum to sulfur of 1:2 to 1:5 and stirring the solution to obtain a solution A;

[0013] (2) adding nickel salt to solution A at a molar ratio of nickel to molybdenum of 0.1:1 to 0.4:1, stirring and mixing to obtain solution B;

[0014] (3) adding a PBTCA aqueous solution to solution B at a molar ratio of phosphorus to molybdenum of 0.05:1 to 0.3:1, stirring to react until a stable complex is formed, and then adjusting the pH of the mixed solution to 4.0 to 7.0;

[0015] (4) subjecting the mixed solution to a hydrothermal reaction at 120 to 240° C. for 8 to 30 hours. After the reaction is completed, the mixed solution is naturally cooled to room temperature, the reaction product is subjected to solid-liquid separation, the solid is collected, and the solid is repeatedly washed with water and anhydrous ethanol in sequence until the pH of the washing solution reaches neutral, and then vacuum dried;

[0016] (5) The dried sample is placed under argon protection and annealed at 300-500° C. for 8-24 h to obtain a nickel-phosphine co-doped molybdenum disulfide composite material.

[0017] Preferably, in step (1), the molybdenum salt is ammonium molybdate or sodium molybdate, and the sulfur source is thiourea or sodium sulfide.

[0018] Preferably, in step (2), the nickel salt is nickel nitrate or nickel chloride.

[0019] Preferably, in step (1), the molar ratio of molybdenum to sulfur is 1:3 to 1:5.

[0020] Preferably, in step (2), the molar ratio of nickel to molybdenum is 0.1:1 to 0.2:1.

[0021] Preferably, in step (3), the molar ratio of phosphorus to molybdenum is 0.1:1 to 0.2:1.

[0022] Preferably, in step (3), the mass concentration of the PBTCA aqueous solution is 50%.

[0023] Preferably, in step (3), the pH is adjusted using 0.1 M sulfuric acid solution or 0.1 M sodium hydroxide solution.

[0024] Preferably, in step (3), the pH is adjusted to 4.0-5.0.

[0025] Preferably, in step (4), the hydrothermal reaction temperature is 160 to 200° C., and the hydrothermal reaction time is 12 to 24 hours.

[0026] Preferably, in step (4), the vacuum drying temperature is 60 to 80° C., and the drying time is 12 to 14 hours.

[0027] Preferably, in step (5), the annealing temperature is 300-400° C., and the annealing time is 16-18 hours.

[0028] The invention provides a nickel-phosphine co-doped molybdenum disulfide composite material prepared by the preparation method.

[0029] Furthermore, the present invention provides the use of the nickel-phosphine co-doped molybdenum disulfide composite material as a catalyst for catalytic activation of peroxymonosulfate to oxidatively degrade organic wastewater.

[0030] The organic wastewater described in the present invention is common wastewater containing organic pollutants that is difficult to degrade, including but not limited to wastewater produced by the preparation of nitrogen pentaanion energetic materials, and wastewater containing one or more of hydrazine hydrate, tetracycline and phenol.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] (1) The nickel-phosphine co-doped molybdenum disulfide composite material of the present invention significantly improves the catalytic activity of MoS through nickel doping and surface modification of PBTCA. The introduction of nickel provides more active sites and enhances the electron transport capacity of the material; the abundant carboxylic acid groups and phosphonic acid groups in the PBTCA molecules can effectively chelate nickel ions to prevent them from precipitation or oxidation during the reaction, and at the same time form a chemical bond with the MoS2 surface, thereby improving the dispersibility, stability and catalytic performance of the material.

[0033] (2) Compared with the traditional MoS2 catalyst, the nickel-phosphine co-doped molybdenum disulfide composite material of the present invention exhibits lower overpotential, higher reaction rate and better degradation effect during the persulfate activation process. In addition, under high-concentration pollutants and complex reaction environments, the catalyst can maintain long-term and efficient catalytic performance, has a long service life, can effectively cope with complex wastewater components, avoids the problem of activity loss during the use of traditional catalysts, and reduces the additional cost caused by repeated replacement of catalysts.

[0034] (3) The present invention uses nickel and PBTCA as main components. Nickel is a common transition metal, and PBTCA is moderately priced and readily available. Therefore, the preparation cost of the nickel-phosphine co-doped molybdenum disulfide composite material is low and suitable for large-scale industrial production.

[0035] (4) The nickel-phosphine co-doped molybdenum disulfide composite material of the present invention is not only suitable for the treatment of wastewater prepared from nitrogen penta-anion energetic materials, but can also be widely used in the treatment of other highly toxic and difficult-to-degrade organic wastewaters. The nickel-phosphine co-doped molybdenum disulfide composite material can maintain a high activity during the wastewater treatment process, and due to its strong anti-pollution ability, its activity can be restored through simple cleaning and regeneration steps. Therefore, it not only has long-term operability, but also can achieve efficient recycling, further reducing the treatment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Optimized structures of nickel-phosphine co-doped molybdenum disulfide composite (a) and organic phosphonic acid PBTCA (b).

[0037] Figure 2 The positions of lone pair electrons in the PBTCA molecule (a) and the complexation of PBTCA with nickel (b).

[0038] Figure 3 SEM (a) and XRD pattern (b) of the nickel-phosphorus co-doped molybdenum disulfide composite material (Ni-P-MoS2) prepared in Example 1.

[0039] Figure 4 The catalysts prepared in Example 1, Comparative Example 2 and Comparative Example 3 have an effect on the COD content of nitrogen penta-anion wastewater after filtering the cobalt salt precipitation. Cr And the degradation effect diagram of NH3-N.

[0040] Figure 5 Figure 2 shows the cyclic performance of the nickel-phosphorus co-doped molybdenum disulfide composite material prepared in Example 1 (a) and the metal ion leaching of the composite material (b). DETAILED DESCRIPTION

[0041] The present invention is described in detail below through examples and drawings, but the use and purpose of these examples are only used to illustrate the present invention, and do not constitute any form of limitation on the actual protection scope of the present invention, nor limit the protection scope of the present invention to them.

[0042] Industrial treatment method for wastewater produced by the preparation of nitrogen penta-anion energetic materials: The wastewater produced by the preparation of nitrogen penta-anion energetic materials has a brown-red appearance. For the treatment of this wastewater, the precipitation method is first used to remove about 97% of the cobalt salts, and the filtrate is oxidized by advanced oxidation technology to remove most of the organic matter and ammonia nitrogen, improve the biodegradability of the difficult-to-degrade organic matter, and reach COD Cr ≤3000mg / L, NH3-N≤500mg / L, which means that the water quality requirements of the factory wastewater biochemical treatment system are met and the wastewater can enter the factory's biochemical treatment system for further comprehensive treatment.

[0043] The laboratory treatment steps of nitrogen penta-anion energetic material preparation wastewater are as follows: add 0.8 g of sodium hydroxide solid to 500 mL of wastewater, stir, and adjust the pH value of the wastewater to 12.5. At this time, a large amount of cobalt hydroxide is generated. The solid-liquid separation method is used to separate the cobalt hydroxide. Then, the nitrogen penta-anion energetic material preparation wastewater after filtering the cobalt salt precipitate is subjected to catalytic oxidation degradation treatment. The main water quality indicators of the wastewater are shown in Table 1.

[0044] In the following embodiments, the specific treatment process of catalytic oxidation degradation treatment of nitrogen penta-anion energetic material preparation wastewater after filtering the cobalt salt precipitate is as follows: accurately weigh 200 mg of nickel phosphine co-doped molybdenum disulfide composite material, add it to 50 mL of nitrogen penta-anion energetic material preparation wastewater after filtering the cobalt salt precipitate, adjust the pH of the wastewater to 7.0 with 0.5 M sulfuric acid, and stir for 30 minutes to reach adsorption-desorption equilibrium. Subsequently, 400 mg of PMS was added under stirring to start the catalytic oxidation degradation experiment. At predetermined time intervals, 2 mL of the solution was taken out at regular intervals and mixed with 200 μL of methanol to terminate the reaction, and then filtered with a 5 mL syringe and a 0.45 μm polyethersulfone filter membrane, and the remaining COD in the filtrate was determined using HACH DR1900. Cr and NH3-N concentration. Due to the complex composition of wastewater, COD Cr The degradation rate of NH3-N and NH3-N is used to reflect the degradation effect of wastewater prepared by all-nitrogen anion energetic materials. The calculation formula of the degradation rate is as follows:

[0045]

[0046] Among them, C0 and C t , are the COD in the solution at 0 and t min, respectively. Cr Or the concentration of NH3-N (mg / L).

[0047] In the following embodiments, the catalyst is tested for its degradation performance on other organic pollutants by adding 20 mg of nickel phosphine co-doped molybdenum disulfide composite material to 50 mL of hydrazine hydrate or tetracycline or phenol solution at a concentration of 20 mg / L, and stirring for 30 minutes to reach adsorption-desorption equilibrium. Subsequently, 50 mg of PMS is added to the above solution and stirring is maintained during the reaction. At intervals, 2 mL of the solution is taken out and mixed with 200 μL of methanol to terminate the reaction, and then filtered with a 5 mL syringe with a 0.45 μm polyethersulfone filter membrane, and the concentration of organic pollutants in the filtrate is determined using an ultraviolet-visible spectrophotometer (UV-Vis). The degradation efficiency of the pollutants is calculated by the following formula:

[0048]

[0049] Among them, C0 and C t , are the concentrations of target pollutants in the solution at 0 and t min, respectively (mg / L).

[0050] In the above-mentioned process of using nickel-phosphine co-doped molybdenum disulfide composite material to treat nitrogen penta-anion energetic material preparation wastewater and testing the degradation performance of other organic pollutants, molybdenum disulfide material was used for parallel experiments as a control group of the composite material.

[0051] Test method for catalyst recycling performance: Recycling performance refers to the ability of a catalyst to maintain high catalytic activity in multiple reaction cycles. In practical applications, catalysts often need to be used multiple times (for example, in industrial reactions, wastewater treatment, etc.), so evaluating the cyclic stability and reusability of catalysts is crucial to their application prospects.

[0052] In the following examples, the catalyst recycling performance experiment: after the degradation reaction of the nitrogen penta-anion energetic material preparation wastewater after filtering the cobalt salt precipitation is completed, the catalyst is separated by centrifugation, washed alternately with deionized water and ethanol for a total of 3 to 4 times, and then ultrasonically cleaned for 10 minutes and placed in a vacuum drying oven, dried at 60°C, and the recovered catalyst is added back to the nitrogen penta-anion energetic material preparation wastewater reaction system after filtering the cobalt salt precipitation, and the catalytic reaction process is repeated. After each cycle, the degradation efficiency is sampled and analyzed to evaluate the stability and catalytic activity of the catalyst.

[0053] In the following embodiments, the metal ion leaching experiment of the catalyst: the ion leaching experiment is mainly used to detect whether the metal elements (such as nickel, molybdenum, etc.) in the catalyst are dissolved from the catalyst surface, which helps to evaluate the stability of the catalyst and whether there is catalyst poisoning. The experimental process is as follows: the catalyst is mixed with deionized water, stirred for 24 hours, and the concentration of metal ions (Ni and Mo) in the aqueous solution is analyzed using an inductively coupled plasma mass spectrometer (ICP-MS). By comparing the concentration of metal ions before and after leaching, the dissolution amount of metal elements in the catalyst is evaluated. For the catalyst after each cycle test, the same method is used to study the metal ion leaching amount. If the leaching amount is too large, it indicates that the catalyst may have a lower stability or the catalyst structure is damaged.

[0054] Example 1

[0055] (1) Weigh 24.19 g of sodium molybdate dihydrate and dissolve it in 100 mL of deionized water to prepare a uniform 0.1 M molybdenum salt solution.

[0056] (2) Add 22.84 thiourea to the molybdenum salt solution and stir evenly. The molar ratio of molybdenum to sulfur is 1:3. This solution is referred to as solution A.

[0057] (3) Weigh 2.628 g of nickel nitrate hexahydrate (nickel / molybdenum molar ratio is 0.1:1), add it to solution A, stir for 20 min, and after the solution is stirred evenly, add 5.984 g of 50% PBTCA aqueous solution, the amount of PBTCA added is P / Mo molar ratio = 0.1:1. Stir the solution until it is completely uniform to ensure that the organic phosphine reacts fully with nickel and molybdenum to form a stable complex, and at the same time adjust the pH of the mixed solution to 5.0 with 0.5 M sulfuric acid solution.

[0058] (4) The mixed solution was transferred to a 250 mL polytetrafluoroethylene-lined stainless steel reactor, sealed and heated to 180°C for 18 hours to ensure uniform doping of nickel ions and PBTCA and promote the growth of the layered structure of molybdenum disulfide. After the reaction was completed, it was naturally cooled to room temperature. The reaction product was then separated by centrifugation, the supernatant was discarded, and the reaction product was repeatedly washed with deionized water and anhydrous ethanol until the pH of the washing solution was close to neutral. The washed solid product was placed in a vacuum drying oven and dried at 80°C for 12 hours.

[0059] (5) The dried sample was placed under argon protection and annealed at 300° C. for 16 hours to obtain a nickel-phosphine co-doped molybdenum disulfide composite material.

[0060] The nickel phosphine co-doped molybdenum disulfide composite material prepared in Example 1 was subjected to the experimental conditions of 4 g / L dosage, 8 g / L PMS dosage, wastewater pH=7.0, and reaction time of 180 min. The COD of the wastewater prepared by the nitrogen penta-anion energetic material after filtering the cobalt salt precipitation was measured. Cr The degradation rates of NH3-N and NH3-N were 96.4% and 86.7% respectively, and the residual COD Cr The concentrations of NH3-N and NH3-N are 900 mg / L and 166 mg / L, respectively, which meet the water inlet requirements of the biochemical system. The nickel-phosphine co-doped molybdenum disulfide composite material prepared in Example 1 has a degradation rate of 94.8%, 93.3% and 90.5% for 20 mg / L hydrazine hydrate, tetracycline and phenol, respectively, under the experimental conditions of 0.4 g / L addition, 1 g / L PMS dosage, 6.5 pH value of wastewater and 120 min reaction time.

[0061] Example 2

[0062] (1) Weigh 24.19 g of sodium molybdate dihydrate and dissolve it in 100 mL of deionized water to prepare a uniform 0.1 M molybdenum salt solution.

[0063] (2) Add 30.45 g of thiourea to the molybdenum salt solution and stir evenly. The molar ratio of molybdenum to sulfur is 1:4. This is referred to as solution A.

[0064] (3) Weigh 3.943 g of nickel nitrate hexahydrate (nickel / molybdenum molar ratio is 0.15:1), add it to solution A, stir for 20 min, and after the solution is stirred evenly, add 2.992 g of 50% PBTCA aqueous solution, the amount of PBTCA added is P / Mo molar ratio = 0.05:1. Stir the solution until it is completely uniform to ensure that the organic phosphine reacts fully with nickel and molybdenum to form a stable complex, and adjust the pH of the mixed solution to 6.0 with 0.5 M sulfuric acid solution.

[0065] (4) The mixed solution was transferred to a 250 mL polytetrafluoroethylene-lined stainless steel reactor, sealed and heated to 160°C for 12 hours to ensure uniform doping of nickel ions and PBTCA and promote the growth of the layered structure of molybdenum disulfide. After the reaction was completed, it was naturally cooled to room temperature. The reaction product was then separated by centrifugation, the supernatant was discarded, and the reaction product was repeatedly washed with deionized water and anhydrous ethanol until the pH of the washing solution was close to neutral. The washed solid product was placed in a vacuum drying oven and dried at 80°C for 12 hours.

[0066] (5) The dried sample was placed under argon protection and annealed at 500° C. for 18 hours to obtain a nickel-phosphine co-doped molybdenum disulfide composite material.

[0067] The nickel phosphine co-doped molybdenum disulfide composite material prepared in Example 2 was subjected to the experimental conditions of 4 g / L dosage, 8 g / L PMS dosage, wastewater pH = 7.0, and reaction time 180 min. The COD of the wastewater prepared by the nitrogen penta-anion energetic material after filtering the cobalt salt precipitation was measured. Cr The degradation rates of NH3-N and NH3-N were 91.3% and 82.4% respectively, and the residual COD Cr The concentrations of NH3-N are 2175 mg / L and 220 mg / L respectively, which meet the inlet requirements of the biochemical system.

[0068] The nickel-phosphine co-doped molybdenum disulfide composite material prepared in Example 2 has a degradation rate of 91.4%, 90.1% and 85.2% for 20 mg / L hydrazine hydrate, tetracycline and phenol respectively under the experimental conditions of 0.4 g / L dosage, 1 g / L PMS dosage, pH of wastewater = 6.5 and reaction time of 120 min. The above results show that the catalyst has an excellent degradation effect on the nitrogen penta-anion energetic material preparation wastewater after filtering the cobalt salt precipitation, and also has good degradation performance for other organic pollutants.

[0069] Example 3

[0070] (1) Weigh 24.19 g of sodium molybdate dihydrate and dissolve it in 100 mL of deionized water to prepare a uniform 0.1 M molybdenum salt solution.

[0071] (2) Then add 15.23 g of thiourea to the molybdenum salt solution and stir evenly. The molar ratio of molybdenum to sulfur is 1:2. This is recorded as solution A.

[0072] (3) Weigh 10.514 g of nickel nitrate hexahydrate (nickel / molybdenum molar ratio is 0.4:1), add it to solution A, stir for 20 min, and after the solution is stirred evenly, add 11.96 g of 50% PBTCA aqueous solution, the amount of PBTCA added is P / Mo molar ratio = 0.3:1. Stir the solution until it is completely uniform to ensure that the organic phosphine reacts fully with nickel and molybdenum to form a stable complex, and at the same time adjust the pH of the mixed solution to 7.0 with 0.5 M sulfuric acid solution.

[0073] (4) The mixed solution was transferred to a 250 mL polytetrafluoroethylene-lined stainless steel reactor, sealed and heated to 200 ° C, and the reaction time was 24 hours to ensure uniform doping of nickel ions and PBTCA and promote the growth of the layered structure of molybdenum disulfide. After the reaction was completed, it was naturally cooled to room temperature. The reaction product was then separated by centrifugation, the supernatant was discarded, and the reaction product was repeatedly washed with deionized water and anhydrous ethanol until the pH of the washing solution was close to neutral. The washed solid product was placed in a vacuum drying oven and dried at 80 ° C for 12 hours.

[0074] (5) The dried sample was placed under argon protection and annealed at 500° C. for 14 hours to obtain a nickel-phosphine co-doped molybdenum disulfide composite material.

[0075] The COD of the wastewater prepared by the nickel-phosphine co-doped molybdenum disulfide composite material after filtering the cobalt salt precipitation was tested under the experimental conditions of 4 g / L dosage, 8 g / L PMS dosage, wastewater pH = 7.0, and reaction time 180 min. Cr The degradation rates of NH3-N and NH3-N were 88.9% and 80.8% respectively, and the residual COD Cr The concentrations of NH3-N are 2775 mg / L and 240 mg / L respectively, which meet the inlet requirements of the biochemical system.

[0076] The nickel-phosphine co-doped molybdenum disulfide composite material prepared in Example 3 has degradation rates of 90.6%, 84.5% and 80.3% for 20 mg / L hydrazine hydrate, tetracycline and phenol respectively under the experimental conditions of 0.4 g / L dosage, 1 g / L PMS dosage, pH value of wastewater = 6.5 and 120 min reaction time. The above results show that the catalyst has good degradation performance for other organic pollutants in addition to the excellent degradation effect for the nitrogen penta-anion energetic material preparation wastewater after filtering the cobalt salt precipitation. However, it is found by comparing Examples 1 and 2 that the doping amounts of sulfur, nickel and phosphine in this example exceed the preferred range, which has a certain influence on the catalytic performance of the composite material.

[0077] Example 4

[0078] (1) Weigh 24.19 g of sodium molybdate dihydrate and dissolve it in 100 mL of deionized water to prepare a uniform 0.1 M molybdenum salt solution.

[0079] (2) Add 38.06 g of thiourea to the molybdenum salt solution and stir evenly. The molar ratio of molybdenum to sulfur is 1:5. This solution is referred to as solution A.

[0080] (3) Weigh 5.257 g of nickel nitrate hexahydrate (nickel / molybdenum molar ratio is 0.2:1), add it to solution A, stir for 20 min, and after the solution is stirred evenly, add 11.97 g of 50% PBTCA aqueous solution, the amount of PBTCA added is P / Mo molar ratio = 0.2:1. Stir the solution until it is completely uniform to ensure that the organic phosphine reacts fully with nickel and molybdenum to form a stable complex, and at the same time adjust the pH of the mixed solution to 4.0 with 0.5 M sulfuric acid solution.

[0081] (4) The mixed solution was transferred to a 250 mL polytetrafluoroethylene-lined stainless steel reactor, sealed and heated to 160°C for 24 hours to ensure uniform doping of nickel ions and PBTCA and promote the growth of the layered structure of molybdenum disulfide. After the reaction was completed, it was naturally cooled to room temperature. The reaction product was then separated by centrifugation, the supernatant was discarded, and the reaction product was repeatedly washed with deionized water and anhydrous ethanol until the pH of the washing solution was close to neutral. The washed solid product was placed in a vacuum drying oven and dried at 80°C for 12 hours.

[0082] (5) The dried sample was placed under argon protection and annealed at 400° C. for 16 hours to obtain a nickel-phosphine co-doped molybdenum disulfide composite material.

[0083] The COD of the wastewater prepared by the nickel-phosphine co-doped molybdenum disulfide composite material after filtering the cobalt salt precipitation was tested under the experimental conditions of 4 g / L of addition amount, 8 g / L of PMS, pH value of wastewater = 7.0, and reaction time of 180 min. Cr The degradation rates of NH3-N and NH3-N were 94.1% and 85.6% respectively, and the residual COD Cr The concentrations of NH3-N and NH3-N were 1475 mg / L and 180 mg / L, respectively, meeting the water inlet requirements of the biochemical system. The nickel-phosphine co-doped molybdenum disulfide composite material prepared in Example 4 had a degradation rate of 93.3%, 92.0% and 88.5% for 20 mg / L hydrazine hydrate, tetracycline and phenol, respectively, under the experimental conditions of 0.4 g / L addition, 1 g / L PMS dosage, pH value of wastewater = 6.5, and 120 min reaction time. The above results show that the catalyst has an excellent degradation effect on the nitrogen penta-anion energetic material preparation wastewater after filtering the cobalt salt precipitation, and also has good degradation performance for other organic pollutants.

[0084] Table 1 shows the main water quality indicators of nitrogen pentaanion preparation wastewater after filtration treatment. It can be seen that COD Cr The content is 25000 mg / L, the NH3-N content is 1250 mg / L, and the remaining cobalt ions are 43 mg / L. It is a high-concentration complex organic wastewater.

[0085] Table 2 compares the catalytic degradation effects of the composite materials prepared in different embodiments and comparative examples, indicating that the performance of mono-molybdenum disulfide undoped with nickel and phosphine is much lower than the catalytic performance of the nickel-phosphine co-doped composite materials of Examples 1 to 4. At the same time, the ratio of the nickel source and the phosphine source will affect the performance of the catalyst.

[0086] Figure 1 The optimized structure of nickel-phosphine co-doped molybdenum disulfide composite material (a) and the optimized structure of organic phosphonic acid PBTCA (b).

[0087] Figure 2 The electrostatic potential distribution diagram of PBTCA (a) and the bond order density (BOD) analysis diagram of the complexation between PBTCA and nickel (b). Figure 2 As can be seen from Figure (a), the electrostatic potential of the oxygen atoms of the phosphonic acid group and the carboxylic acid group in PBTCA is low, and they can provide lone pairs of electrons to coordinate with nickel. Figure 2 As can be seen from Figure (b), both the oxygen atoms of the phosphonic acid group and the oxygen atoms of the carboxylic acid group can coordinate with nickel. According to the size of the isosurface, the coordination ability of the former with nickel is stronger than that of the latter.

[0088] Figure 3 The SEM (a) and XRD diagram (b) of the nickel-phosphorus co-doped molybdenum disulfide composite material (Ni-P-MoS2) prepared in Example 1 show that the prepared composite material is in the form of superimposed thin sheets, similar to a petal-like morphology. This structure originates from the lattice arrangement of the three-layer stacking of sulfur-molybdenum-sulfur in MoS, indicating that the co-doping of nickel and phosphine does not destroy the layered structure of molybdenum disulfide. It can be seen from XRD that the diffraction peaks at 2θ=14.1° and 32.9° correspond to the characteristic crystal planes (0 02) and (1 0 0) of molybdenum disulfide, respectively. Due to the doping of nickel and organic phosphine, the crystallinity of the composite material is affected.

[0089] Figure 4 COD of the nickel-phosphorus co-doped molybdenum disulfide composite material prepared in Examples 1 to 4 at different reaction times Cr and the degradation rate of NH3-N.

[0090] Figure 5 Figure 1 shows the recycling performance of the nickel-phosphorus co-doped molybdenum disulfide composite material prepared in Example 1 (a) and the metal ion leaching result of the composite material (b). Figure 5 It can be seen that the nickel-phosphine co-doped molybdenum disulfide composite material has good recycling performance. At the same time, the good complexation between PBTCA and metal ions gives the nickel-phosphine co-doped molybdenum disulfide material excellent stability and low metal ion leaching.

[0091] Table 1 Main water quality indicators of nitrogen pentaanion preparation wastewater after filtration treatment

[0092]

[0093] Table 2 Catalytic degradation performance of the composite materials prepared in different embodiments and comparative examples

[0094]

[0095] Comparative Example 1

[0096] (1) Weigh 24.19 g of sodium molybdate dihydrate and dissolve it in 100 mL of deionized water to prepare a uniform 0.1 M molybdenum salt solution.

[0097] (2) Add 38.06 g of thiourea to the molybdenum salt solution and stir evenly. The molar ratio of molybdenum to sulfur is 1:5. This solution is referred to as solution A.

[0098] (3) Weigh 15.77 g of nickel nitrate hexahydrate (nickel / molybdenum molar ratio is 0.6:1), add it to solution A, stir for 20 min, and after the solution is stirred evenly, add 11.97 g of 50% PBTCA aqueous solution, the amount of PBTCA added is P / Mo molar ratio = 0.2:1. Stir the solution until it is completely uniform to ensure that the organic phosphine reacts fully with nickel and molybdenum to form a stable complex, and at the same time adjust the pH of the mixed solution to 5.0 with 0.5 M sulfuric acid solution.

[0099] (4) The mixed solution was transferred to a 250 mL polytetrafluoroethylene-lined stainless steel reactor, sealed and heated to 160°C for 24 hours to ensure uniform doping of nickel ions and PBTCA and promote the growth of the layered structure of molybdenum disulfide. After the reaction was completed, it was naturally cooled to room temperature. The reaction product was then separated by centrifugation, the supernatant was discarded, and the reaction product was repeatedly washed with deionized water and anhydrous ethanol until the pH of the washing solution was close to neutral. The washed solid product was placed in a vacuum drying oven and dried at 80°C for 12 hours.

[0100] (5) The dried sample was placed under argon protection and annealed at 400° C. for 18 hours to obtain a nickel-phosphine co-doped molybdenum disulfide composite material.

[0101] The COD of the wastewater prepared by the nickel-phosphine co-doped molybdenum disulfide composite material after filtering the cobalt salt precipitation was measured under the experimental conditions of 4 g / L dosage, 8 g / L PMS dosage, wastewater pH = 7.0, and reaction time 180 min. Cr The degradation rates of NH3-N and NH3-N were 80.1% and 74.3% respectively, and the residual COD Cr The concentrations of N and NH3-N are 4975 mg / L and 321 mg / L respectively, which cannot meet the influent requirements of the biochemical system.

[0102] Under the experimental conditions of 0.4 g / L of the nickel-phosphine co-doped molybdenum disulfide composite material, 1 g / L of PMS, pH value of wastewater = 6.5, and 120 min of reaction time, the degradation rates of 20 mg / L of hydrazine hydrate, tetracycline, and phenol were 81.3%, 80.5%, and 76.4%, respectively. By comparing the comparative example 1 with the examples 1 to 4, it can be found that the nickel doping ratio has a great influence on the performance of the composite catalyst.

[0103] Comparative Example 2

[0104] (1) Weigh 24.19 g of sodium molybdate dihydrate and dissolve it in 100 mL of deionized water to prepare a uniform 0.1 M molybdenum salt solution.

[0105] (2) Add 38.06 g of thiourea to the molybdenum salt solution and stir evenly. The molar ratio of molybdenum to sulfur is 1:4. This solution is referred to as solution A.

[0106] (3) Weigh 5.257 g of nickel nitrate hexahydrate (nickel / molybdenum molar ratio is 0.2:1), add it to solution A, stir for 20 min, and after the solution is stirred evenly, add 29.93 g of 50% PBTCA aqueous solution, the amount of PBTCA added is P / Mo molar ratio = 0.5:1. Stir the solution until it is completely uniform to ensure that the organic phosphine reacts fully with nickel and molybdenum to form a stable complex, and at the same time adjust the pH of the mixed solution to 5.0 with 0.5 M sulfuric acid solution.

[0107] (4) The mixed solution was transferred to a 250 mL polytetrafluoroethylene-lined stainless steel reactor, sealed and heated to 160°C for 24 hours to ensure uniform doping of nickel ions and PBTCA and promote the growth of the layered structure of molybdenum disulfide. After the reaction was completed, it was naturally cooled to room temperature. The reaction product was then separated by centrifugation, the supernatant was discarded, and the reaction product was repeatedly washed with deionized water and anhydrous ethanol until the pH of the washing solution was close to neutral. The washed solid product was placed in a vacuum drying oven and dried at 80°C for 12 hours.

[0108] (5) The dried sample was placed under argon protection and annealed at 400° C. for 18 hours to obtain a nickel-phosphine co-doped molybdenum disulfide composite material.

[0109] The COD of the wastewater prepared by the nickel-phosphine co-doped molybdenum disulfide composite material after filtering the cobalt salt precipitation was measured under the experimental conditions of 4 g / L dosage, 8 g / L PMS dosage, wastewater pH = 7.0, and reaction time 180 min. Cr The degradation rates of NH3-N and NH3-N were 78.4% and 65.9% respectively, and the residual COD Cr The concentrations of NH3-N are 5400 mg / L and 426 mg / L respectively, which cannot meet the influent requirements of the biochemical system.

[0110] Under the experimental conditions of 0.4 g / L of the nickel-phosphine co-doped molybdenum disulfide composite material, 1 g / L of PMS, pH value of wastewater = 6.5, and 120 min of reaction time, the degradation rates of 20 mg / L of hydrazine hydrate, tetracycline, and phenol were 70.1%, 71.3%, and 68.6%, respectively. By comparing Comparative Example 2 with Examples 1 to 4, it can be seen that the doping ratio of the organic phosphine has a great influence on the performance of the composite catalyst.

[0111] Comparative Example 3

[0112] (1) Weigh 24.19 g of sodium molybdate dihydrate and dissolve it in 100 mL of deionized water to prepare a uniform 0.1 M molybdenum salt solution.

[0113] (2) Add 30.45 g of thiourea to the molybdenum salt solution and stir evenly. The molar ratio of molybdenum to sulfur is 1:4. This is referred to as solution A.

[0114] (3) Weigh 5.257 g of nickel nitrate hexahydrate (nickel / molybdenum molar ratio is 0.2:1), add it to solution A, stir for 20 min, and after the solution is stirred evenly, add 5.985 g of 50% PBTCA aqueous solution, the amount of PBTCA added is P / Mo molar ratio = 0.1:1. Stir the solution until it is completely uniform to ensure that the organic phosphine reacts fully with nickel and molybdenum to form a stable complex, and adjust the pH of the mixed solution to 5.0 with 0.5 M sulfuric acid solution.

[0115] (4) The mixed solution was transferred to a 250 mL polytetrafluoroethylene-lined stainless steel reactor, sealed and heated to 160 ° C, and the reaction time was 30 hours to ensure uniform doping of nickel ions and PBTCA and promote the growth of the layered structure of molybdenum disulfide. After the reaction was completed, it was naturally cooled to room temperature. The reaction product was then separated by centrifugation, the supernatant was discarded, and the reaction product was repeatedly washed with deionized water and anhydrous ethanol until the pH of the washing solution was close to neutral. The washed solid product was placed in a vacuum drying oven and dried at 80 ° C for 12 hours.

[0116] (5) The dried sample was placed under argon protection and annealed at 700° C. for 12 hours to obtain a nickel-phosphine co-doped molybdenum disulfide composite material.

[0117] The COD of the wastewater prepared by the nickel-phosphine co-doped molybdenum disulfide composite material after filtering the cobalt salt precipitation was measured under the experimental conditions of 4 g / L dosage, 8 g / L PMS dosage, wastewater pH = 7.0, and reaction time 180 min. Cr The degradation rates of NH3-N and NH3-N were 85.3% and 77.8% respectively, and the residual COD CrThe concentrations of NH3-N are 3675 mg / L and 277 mg / L respectively, which cannot meet the influent requirements of the biochemical system.

[0118] The nickel-phosphine co-doped molybdenum disulfide composite material prepared in Comparative Example 3 has degradation rates of 84.6%, 82.2% and 77.4% for 20 mg / L hydrazine hydrate, tetracycline and phenol respectively under the experimental conditions of 0.4 g / L addition amount, 1 g / L PMS dosage, pH value of wastewater = 6.5 and 120 min reaction time. By comparing Comparative Example 3 with Examples 1 to 4, it can be seen that the annealing temperature has a great influence on the performance of the composite catalyst.

[0119] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A method for preparing a nickel-phosphine co-doped molybdenum disulfide composite material, characterized in that: The specific steps include: (1) adding a sulfur source to a molybdenum salt solution having a concentration of 0.1 to 0.5 M according to a molar ratio of molybdenum to sulfur of 1:2 to 1:5 and stirring the solution to obtain a solution A; (2) adding nickel salt to solution A at a molar ratio of nickel to molybdenum of 0.1:1 to 0.4:1, stirring and mixing to obtain solution B; (3) adding a PBTCA aqueous solution to solution B at a molar ratio of phosphorus to molybdenum of 0.05:1 to 0.3:1, stirring the mixture to react until a stable complex is formed, and then adjusting the pH of the mixed solution to 4.0 to 7.0; (4) subjecting the mixed solution to a hydrothermal reaction at 120-240°C for 8-30 h. After the reaction is completed, the mixed solution is naturally cooled to room temperature, the reaction product is subjected to solid-liquid separation, the solid is collected, and the solid is repeatedly washed with water and anhydrous ethanol in sequence until the pH of the washing solution reaches neutral, and then dried in a vacuum; (5) The dried sample was placed under argon protection and annealed at 300-500 °C for 8-24 h to obtain a nickel-phosphine co-doped molybdenum disulfide composite material.

2. The preparation method according to claim 1, characterized in that: In step (1), the molybdenum salt is ammonium molybdate or sodium molybdate, and the sulfur source is thiourea or sodium sulfide; in step (2), the nickel salt is nickel nitrate or nickel chloride.

3. The preparation method according to claim 1, characterized in that: In step (1), the molar ratio of molybdenum to sulfur is 1:3-1:5; in step (2), the molar ratio of nickel to molybdenum is 0.1:1-0.2:1; in step (3), the molar ratio of phosphorus to molybdenum is 0.1:1-0.2:

1.

4. The preparation method according to claim 1, characterized in that In step (3), the mass concentration of the PBTCA aqueous solution is 50%; the pH is adjusted using a 0.1 M sulfuric acid solution or a 0.1 M sodium hydroxide solution.

5. The preparation method according to claim 1, characterized in that: In step (3), the pH is adjusted to 5.0-7.

0.

6. The preparation method according to claim 1, characterized in that In step (4), the hydrothermal reaction temperature is 160-200°C, and the hydrothermal reaction time is 12-24 h; the vacuum drying temperature is 60-80°C, and the drying time is 12-14 h.

7. The preparation method according to claim 1, characterized in that In step (5), the annealing temperature is 300-400°C, and the annealing time is 16-18 h.

8. A nickel-phosphine co-doped molybdenum disulfide composite material obtained according to the preparation method described in any one of claims 1 to 7.

9. Use of the nickel-phosphine co-doped molybdenum disulfide composite material according to claim 8 as a catalyst for catalytic activation of peroxymonosulfate for oxidative degradation of organic wastewater.

10. The use according to claim 9, characterized in that: The organic wastewater is wastewater produced from the preparation of nitrogen pentaanion energetic materials, or wastewater containing one or more of hydrazine hydrate, tetracycline and phenol.

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