A foam titanium-based catalytic reaction filter loaded with nano ruthenium palladium tin alloy and a preparation method and application thereof

Abstract

This invention provides a foamed titanium-based catalytic reaction filter membrane supported on nano-ruthenium-palladium-tin alloy, its preparation method, and its application, belonging to the field of water treatment technology. The invention involves spraying a mixed solution of metal precursors containing ruthenium, palladium, and tin onto the etched surface of foamed titanium to obtain foamed titanium containing ruthenium, palladium, and tin. The foamed titanium containing ruthenium, palladium, and tin is then immersed in a reducing agent to obtain the foamed titanium-based catalytic reaction filter membrane supported on nano-ruthenium-palladium-tin alloy. The foamed titanium-based catalytic reaction filter membrane prepared by this invention exhibits high loading intensity of active metal components and stable catalytic performance. Furthermore, in the chemical reaction process involved in this invention, formic acid acts as an electron donor to drive the reaction, eliminating the need for additional electrical energy. Compared to traditional electrochemical nitrate reduction technology, this invention avoids the construction of complex electrolytic cells, significantly reducing equipment manufacturing costs and operational requirements. This invention shows broad application prospects in wastewater denitrification and nitrogen resource recovery.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a foam titanium-based catalytic reaction filter membrane supported on nano-ruthenium palladium tin alloy, its preparation method, and its application. Background Technology

[0002] Nitrogen pollution in aquatic environments has become a global environmental problem. In many regions, due to the excessive use of nitrogen fertilizers and improper treatment of domestic sewage and nitrogen-containing industrial wastewater, nitrates have become one of the main pollutants in surface water and groundwater. Currently, the physicochemical treatment methods for nitrate wastewater mainly include ion exchange, electrodialysis, and reverse osmosis. However, these methods can only achieve the separation and enrichment of nitrates and cannot reduce nitrates to nitrogen gas to achieve atmospheric nitrogen cycling. In addition, considering that artificial nitrogen fixation processes consume large amounts of fossil energy and generate large amounts of carbon emissions, achieving efficient nitrogen recovery is of great significance for the resource utilization of nitrate wastewater.

[0003] Electrochemical nitrate reduction technology is a highly efficient, simple, and easy-to-operate denitrification method: during electrolysis, nitrate gains electrons at the cathode and is catalytically reduced to ammonia. After electrolysis, ammonia removal and recovery can be quickly achieved through a two-step stripping-absorption process. However, for wastewater with low salinity, the cell voltage during electrolysis is often very high, leading to high energy consumption. Furthermore, calcium and magnesium ions in the water can easily deposit on the electrode surface, covering active sites and reducing electrode activity. These unfavorable factors limit the implementation of electrochemical nitrate reduction technology. Catalytic reduction of nitrate is a process that uses hydrogen as an electron donor to reduce nitrate under the action of a catalyst, without the need for a power source or electrode equipment. Compared with electrochemical reduction methods, this catalytic approach is more suitable for treating wastewater with low electrolyte concentrations or containing calcium and magnesium ions. However, in traditional nitrate catalytic reduction treatment, the active metal is often loaded onto a powder carrier using an impregnation method to prepare the catalyst. This can easily lead to the detachment of the active metal, reducing catalytic activity and hindering catalyst recovery. Therefore, high-temperature sintering to firmly load active metals onto bulk materials can improve the stability of catalytic activity and facilitate catalyst recovery and reuse. Furthermore, hydrogen, as a flammable and explosive gas, poses a high operational risk during use, and its low solubility in water significantly reduces its utilization rate, leading to increased wastewater treatment costs. In contrast, formic acid, as an inexpensive, easily transported and stored industrial product, not only possesses high reducing power, but more importantly, its decomposition product is CO2, posing no risk of secondary pollution. Therefore, using formic acid as an electron donor for the catalytic reduction of nitrates is a more ideal approach. Summary of the Invention

[0004] The purpose of this invention is to provide a foamed titanium-based catalytic reaction filter membrane supported on nano-ruthenium palladium tin alloy, its preparation method and application, to solve the technical problems of low catalytic activity of existing nitrate catalysts and difficulty in realizing the resource utilization of nitrate.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing a foamed titanium-based catalytic reaction filter membrane supported on nano-ruthenium palladium tin alloy, comprising the following steps:

[0007] 1) Under heating conditions, a mixed solution of metal precursors containing ruthenium, palladium and tin is sprayed onto the etched foamed titanium surface to obtain foamed titanium containing ruthenium, palladium and tin.

[0008] 2) Immerse titanium foam containing ruthenium, palladium and tin in a reducing agent to obtain a titanium foam-based catalytic reaction filter membrane loaded with nano-ruthenium-palladium-tin alloy.

[0009] Furthermore, the heating temperature is 150–750°C.

[0010] Furthermore, the etching is performed using an oxalic acid aqueous solution with a concentration of 1–10 wt%, an etching temperature of 50–130 °C, and an etching time of 1–700 min.

[0011] Furthermore, the ruthenium, palladium and tin-containing metal precursor mixed solution contains ruthenium metal precursor solution, palladium metal precursor solution and tin metal precursor solution in equal volume ratios.

[0012] Furthermore, in the ruthenium, palladium, and tin-containing metal precursor mixed solution, the ruthenium metal precursor comprises one or more of ruthenium trichloride, ruthenium acetate, ammonium hexachlororuthenate, and ruthenium acetylacetonate; the palladium metal precursor comprises one or more of palladium dichloride, palladium chloroacetate, sodium palladium chloroacetate, palladium acetylacetonate, and palladium nitrate; and the tin metal precursor comprises tin tetrachloride and / or tin dichloride.

[0013] Furthermore, in the ruthenium, palladium and tin-containing foamed titanium, the ruthenium loading is 0.001 to 10 wt%, the palladium loading is 0.001 to 15 wt%, and the tin loading is 0.001 to 45 wt%.

[0014] Furthermore, the reducing agent comprises one or more of sodium borohydride solution, potassium borohydride solution, dimethylaminoborane solution, lithium aluminum hydride solution, and hydrazine hydrate solution, the concentration of the reducing agent is 1–1200 mmol / L, and the soaking treatment time is 0.1–90 min.

[0015] Furthermore, the titanium foam contains ≥85wt% titanium, has a pore size of 20-90μm, and a thickness of 0.1-3mm.

[0016] The present invention also provides a foam titanium-based catalytic reaction filter membrane supported on nano-ruthenium palladium tin alloy.

[0017] The present invention also provides an application of a foam titanium-based catalytic reaction filter membrane supported on nano-ruthenium palladium tin alloy in the treatment of nitrate wastewater. The foam titanium-based catalytic reaction filter membrane supported on nano-ruthenium palladium tin alloy is installed in a flow tank. Nitrate wastewater with added formic acid flows through the filter membrane. The formic acid is catalytically decomposed and generates electrons. The nitrate gains electrons and is reduced to ammonia.

[0018] The purity of the formic acid is 70-100%, and the molar ratio of formic acid to nitrate in the nitrate wastewater is 0.1-60:1.

[0019] The beneficial effects of this invention are:

[0020] 1. This invention uses formic acid as an electron donor, avoiding the risk of hydrogen leakage in the traditional hydrogen reduction process, and greatly reducing the manufacturing cost and operating requirements of the equipment.

[0021] 2. The nano-ruthenium palladium tin alloy of the present invention has excellent formic acid decomposition performance, which helps to improve the catalytic reduction rate of nitrate and ammonia selectivity.

[0022] 3. This invention uses a high-temperature sintering + chemical reduction method to load nano-ruthenium palladium tin alloy onto a foamed titanium substrate. The high porosity of the foamed titanium provides a high surface area, which is beneficial to the fixation and stability of the active metal components.

[0023] 4. The process of catalytically reducing nitrate wastewater with nano-ruthenium-palladium-tin alloy foam achieves efficient utilization and convenient recovery of the catalyst. Compared with the method of directly adding powdered catalyst, this method simplifies the operation process and reduces operational complexity. Attached Figure Description

[0024] Figure 1 This is a scanning electron microscope image of the catalytic reaction filter membrane of Example 1 of the present invention;

[0025] Figure 2 This is a transmission electron microscope image of nano-ruthenium palladium tin alloy particles in the catalytic reaction filter membrane of Example 1 of the present invention;

[0026] Figure 3 This is a schematic diagram of the nitrate reduction process apparatus according to an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram illustrating the technical principle of the nitrate reduction process in an embodiment of the present invention. Detailed Implementation

[0028] This invention provides a method for preparing a foamed titanium-based catalytic reaction filter membrane supported on nano-ruthenium palladium tin alloy, comprising the following steps:

[0029] 1) Under heating conditions, a mixed solution of metal precursors containing ruthenium, palladium and tin is sprayed onto the etched foamed titanium surface to obtain foamed titanium containing ruthenium, palladium and tin.

[0030] 2) Immerse titanium foam containing ruthenium, palladium and tin in a reducing agent to obtain a titanium foam-based catalytic reaction filter membrane loaded with nano-ruthenium-palladium-tin alloy.

[0031] In this invention, the heating temperature is 150-750°C, preferably 200-600°C, and more preferably 350-450°C.

[0032] In this invention, the etching is performed using an oxalic acid aqueous solution, wherein the concentration of the oxalic acid aqueous solution is 1-10 wt%, preferably 2-8 wt%, and more preferably 3-6 wt%; the etching temperature is 50-130°C, preferably 60-120°C, and more preferably 80-100°C; and the etching time is 1-700 min, preferably 100-600 min, and more preferably 200-400 min.

[0033] In this invention, the mixed solution of ruthenium, palladium and tin metal precursors contains ruthenium metal precursor solution, palladium metal precursor solution and tin metal precursor solution in equal volume ratios.

[0034] In this invention, the solvents in the ruthenium metal precursor solution, palladium metal precursor solution, and tin metal precursor solution independently include one or more of water, ethanol, acetone, acetonitrile, ethylene glycol, and isopropanol.

[0035] In this invention, the ruthenium metal precursor mixed solution containing ruthenium, palladium and tin is preferably one or more of ruthenium trichloride, ruthenium acetate, ammonium hexachlororuthenate and ruthenium acetylacetonate; the palladium metal precursor is preferably one or more of palladium dichloride, palladium chloroacetate, sodium palladium chloroacetate, palladium acetylacetonate and palladium nitrate; and the tin metal precursor is preferably tin tetrachloride and / or tin dichloride.

[0036] In this invention, the ruthenium-, palladium-, and tin-containing foamed titanium contains ruthenium with a loading of 0.001–10 wt%, preferably 0.1–8 wt%, more preferably 0.1–6 wt%; palladium with a loading of 0.001–15 wt%, preferably 0.1–10 wt%, more preferably 0.1–8 wt%; and tin with a loading of 0.001–45 wt%, preferably 0.1–30 wt%, more preferably 0.1–25 wt%.

[0037] In this invention, the reducing agent comprises one or more of sodium borohydride solution, potassium borohydride solution, dimethylaminoborane solution, lithium aluminum hydride solution, and hydrazine hydrate solution, preferably one or more of sodium borohydride solution, potassium borohydride solution, and hydrazine hydrate solution; the concentration of the reducing agent is 1–1200 mmol / L, preferably 10–1000 mmol / L, more preferably 100–800 mmol / L; the soaking time is 0.1–90 min, preferably 1–80 min, more preferably 20–60 min.

[0038] In this invention, the titanium content in the foamed titanium is ≥85wt%, preferably ≥95wt%; the pore size of the foamed titanium is 20-90μm, preferably 30-80μm, and more preferably 40-60μm; the thickness is 0.1-3mm, preferably 1-2mm.

[0039] The present invention also provides a foam titanium-based catalytic reaction filter membrane supported on nano-ruthenium palladium tin alloy.

[0040] The present invention also provides an application of a foam titanium-based catalytic reaction filter membrane supported on nano-ruthenium palladium tin alloy in the treatment of nitrate wastewater. The foam titanium-based catalytic reaction filter membrane supported on nano-ruthenium palladium tin alloy is installed in a flow tank. Nitrate wastewater with added formic acid flows through the filter membrane. The formic acid is catalytically decomposed and generates electrons. The nitrate gains electrons and is reduced to ammonia.

[0041] The purity of the formic acid is 70-100%, and the molar ratio of formic acid to nitrate in the nitrate wastewater is 0.1-60:1.

[0042] In this invention, the purity of the formic acid is preferably 80-90%, more preferably 85%; the molar ratio of formic acid to nitrate in nitrate wastewater is 0.1-60:1, preferably 1-50:1, more preferably 10-40:1.

[0043] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0044] Example 1

[0045] In this embodiment, the titanium foam used has a titanium content of more than 95%, a size of 40 mm × 40 mm, a thickness of 1 mm, and a pore size of 50 μm.

[0046] Preparation steps of foamed titanium-based catalytic reaction filter membrane:

[0047] 1) Immerse the foamed titanium in a 10wt% oxalic acid solution at 90℃ for surface etching for 150 min. After etching, remove the foamed titanium and rinse the surface with water.

[0048] 2) Heat the foamed titanium to 450°C on a heating stage. Dissolve ruthenium trichloride as a ruthenium metal precursor in water, palladium dichloride as a palladium metal precursor in water, and tin tetrachloride as a tin metal precursor in ethanol. Then, mix equal volumes of the three solutions and spray them onto the surface of the foamed titanium, ensuring a constant temperature during spraying. The loading amounts of ruthenium, palladium, and tin are 0.01 wt%. After spraying, remove the foamed titanium and cool it to room temperature.

[0049] 3) The above-mentioned foamed titanium was immersed in a 500 mmol / L sodium borohydride aqueous solution for 40 min. After immersion, the foamed titanium was removed and the surface was rinsed with water to obtain a foamed titanium-based catalytic reaction filter membrane supported on nano-ruthenium palladium tin alloy. A scanning electron microscope image of this catalytic reaction filter membrane is shown below. Figure 1 As shown in the transmission electron microscope (TEM) image of the nano-ruthenium palladium tin alloy particles, see below. Figure 2 As shown.

[0050] Nitrate catalytic reduction process:

[0051] 1) A certain amount of formic acid (purity 99.5%) was added to simulated nitrate-containing wastewater (200 mL, 100.6 mg / L) in advance. The ratio of formic acid concentration to nitrate molar concentration was 5:1.

[0052] 2) A schematic diagram of the apparatus for the nitrate reduction process is shown below. Figure 3 As shown: The foamed titanium-based catalytic reaction filter membrane 1 is placed in the flow tank 2. The water pump 3 pumps wastewater from the storage tank 4 into the flow tank 2 at a flow rate of 40 mL / min. Then the wastewater flows through the filter membrane 1 and returns to the storage tank 4. The device runs for 4 hours.

[0053] 3) The technical principle of the nitrate reduction process is as follows: Figure 4 As shown: when wastewater flows through the filter membrane, formic acid is catalytically decomposed on the nano-ruthenium palladium tin alloy, releasing electrons; at the same time, nitrate gains electrons on the nano-ruthenium palladium tin alloy and undergoes a reduction reaction, converting into ammonia.

[0054]

[0055] After the reaction was completed, the relevant index results are shown in Table 1.

[0056] Table 1

[0057]

[0058] The above results indicate that the foamed titanium-based catalytic reaction filter membrane proposed in this invention has good nitrate reduction performance, with a nitrate removal rate of 87.6% and an ammonia selectivity of 60.0%.

[0059] Example 2

[0060] In this embodiment, the ruthenium loading was increased from 0.01 wt% to 0.02 wt%, while other conditions remained the same as in Example 1.

[0061] After the reaction was completed, the relevant index results are shown in Table 2.

[0062] Table 2

[0063]

[0064]

[0065] The above results indicate that increasing the ruthenium loading helps to significantly improve the nitrate reduction rate and ammonia selectivity, with the nitrate removal rate increasing to 98.8% and the ammonia selectivity increasing to 100.0%.

[0066] Example 3

[0067] In this embodiment, the palladium loading was increased from 0.1 wt% to 0.15 wt%, while other conditions remained the same as in Example 1.

[0068] The results of the relevant indicators after the reaction were completed are shown in Table 3.

[0069] Table 3

[0070]

[0071] The above results indicate that increasing the palladium loading significantly improves the nitrate reduction rate, increasing the nitrate removal rate to 99.5%, but the change in ammonia selectivity is not significant.

[0072] Example 4

[0073] In this embodiment, the tin loading was increased from 0.1 wt% to 0.15 wt%, while other conditions remained the same as in Example 1.

[0074] After the reaction was completed, the relevant index results are shown in Table 4.

[0075] Table 4

[0076]

[0077] The above results indicate that increasing the tin loading helps to significantly improve the nitrate reduction rate, increasing the nitrate removal rate to 96.2%, but the change in ammonia selectivity is not significant.

[0078] Comparative Example 1

[0079] To verify the role of formic acid, in this comparative example, except that formic acid was not added to the nitrate wastewater, all other conditions were kept the same as in Example 1.

[0080] After the reaction was completed, the relevant indicators were as follows.

[0081] Table 5

[0082]

[0083] In this comparative example, the catalytic reduction of nitrate could not proceed due to the lack of formic acid as an electron donor.

[0084] Example 5

[0085] In this embodiment, actual wastewater will be used as the treatment target, and the treatment volume will be increased. The wastewater comes from the parts pickling workshop of COMAC Shanghai Aircraft Manufacturing Co., Ltd., which generates high-concentration nitrate wastewater year-round.

[0086] In this embodiment, the titanium foam used has a titanium content of more than 95%, a size of 40 mm × 40 mm, a thickness of 1 mm, and a pore size of 50 micrometers.

[0087] Preparation steps of foamed titanium-based catalytic reaction filter membrane:

[0088] 1) Immerse the foamed titanium in a 10wt% oxalic acid solution at 90℃ for surface etching for 150 min. After etching, remove the foamed titanium and rinse the surface with water.

[0089] 2) Heat the foamed titanium to 450°C on a heating stage. Dissolve ruthenium trichloride as a ruthenium metal precursor in water, palladium dichloride as a palladium metal precursor in water, and tin tetrachloride as a tin metal precursor in ethanol. Then, mix equal volumes of the three solutions and spray them onto the surface of the foamed titanium, ensuring a constant temperature during spraying. The loading amounts of ruthenium, palladium, and tin are 0.05 wt%, 0.2 wt%, and 0.2 wt%, respectively. After spraying, remove the foamed titanium and cool it to room temperature.

[0090] 3) Immerse the above-mentioned foamed titanium in a 600 mmol / L sodium borohydride aqueous solution for 40 min. After immersion, remove the foamed titanium and rinse the surface with water to obtain a foamed titanium-based catalytic reaction filter membrane loaded with nano-ruthenium palladium tin alloy.

[0091] Nitrate catalytic reduction process:

[0092] 1) Add a certain amount of formic acid (purity 99.5%) to nitrate wastewater (200 mL, wastewater quality as shown in Table 6) in advance. The ratio of formic acid concentration to nitrate molar concentration is 6:1.

[0093] 2) The operation procedure for nitrate reduction is the same as in Example 1, with a water flow rate of 40 mL / min and a device running time of 4 hours.

[0094] Table 6

[0095] index numerical values Nitrate concentration (mg / L) 145.9 Ammonia (mg / L) 0.5

[0096] After the reaction was completed, the relevant index results are shown in Table 7.

[0097] Table 7

[0098]

[0099] In this embodiment, for actual nitrate wastewater, the foamed titanium-based catalytic reaction filter membrane proposed in this invention still exhibits excellent nitrate removal efficiency and ammonia selectivity, demonstrating broad application prospects.

[0100] As can be seen from the above embodiments, the present invention provides a foamed titanium-based catalytic reaction filter membrane supported on nano-ruthenium palladium tin alloy, its preparation method, and its application. In the chemical reaction process involved in the present invention, formic acid acts as an electron donor to drive the reaction, eliminating the need for additional electrical energy. Compared with traditional electrochemical nitrate reduction technology, the present invention avoids the construction of complex electrolytic cells, greatly reducing the manufacturing cost and operational requirements of the equipment. The present invention shows broad application prospects in the fields of wastewater denitrification and nitrogen resource recovery.

[0101] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of a foamed titanium-based catalytic reaction filter membrane supported on nano-ruthenium palladium tin alloy in the treatment of nitrate wastewater, characterized in that, A foamed titanium-based catalytic reaction filter membrane loaded with nano-ruthenium palladium tin alloy was installed in a flow tank. Nitrate wastewater with added formic acid was flowed through the filter membrane. The formic acid was catalytically decomposed and generated electrons, and the nitrate was reduced to ammonia by gaining electrons. The purity of the formic acid is 70-100%, and the molar ratio of formic acid to nitrate in nitrate wastewater is 0.1-60:

1. The method for preparing the foamed titanium-based catalytic reaction filter membrane supported on nano-ruthenium palladium tin alloy includes the following steps: 1) Under heating conditions, a mixed solution of metal precursors containing ruthenium, palladium and tin is sprayed onto the etched foamed titanium surface to obtain foamed titanium containing ruthenium, palladium and tin. 2) Immerse titanium foam containing ruthenium, palladium and tin in a reducing agent to obtain a titanium foam-based catalytic reaction filter membrane loaded with nano-ruthenium-palladium-tin alloy. In the ruthenium, palladium and tin-containing foamed titanium, the ruthenium loading is 0.02 wt%, the palladium loading is 0.1 wt%, and the tin loading is 0.1 wt%.

2. The application according to claim 1, characterized in that, The heating temperature is 150~750℃.

3. The application according to claim 1 or 2, characterized in that, The etching is performed using an oxalic acid aqueous solution with a concentration of 1-10 wt%, an etching temperature of 50-130°C, and an etching time of 1-700 min.

4. The application according to claim 3, characterized in that, The ruthenium, palladium and tin-containing metal precursor mixed solution contains ruthenium metal precursor solution, palladium metal precursor solution and tin metal precursor solution in equal volume ratios.

5. The application according to claim 4, characterized in that, In the ruthenium, palladium and tin metal precursor mixed solution, the ruthenium metal precursor includes one or more of ruthenium trichloride, ruthenium acetate, ammonium hexachlororuthenate and ruthenium acetylacetonate; the palladium metal precursor includes one or more of palladium dichloride, palladium chloroacetate, sodium palladium chloroacetate, palladium acetylacetonate and palladium nitrate; and the tin metal precursor includes tin tetrachloride and / or tin dichloride.

6. The application according to claim 1, 2, 4, or 5, characterized in that, The reducing agent comprises one or more of sodium borohydride solution, potassium borohydride solution, dimethylaminoborane solution, lithium aluminum hydride solution, and hydrazine hydrate solution, wherein the concentration of the reducing agent is 1~1200 mmol / L, and the soaking time is 0.1~90 min.

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