A kind of iron oxyhydroxide catalyst and preparation method thereof

Abstract

The present application relates to the field of catalyst technology, and specifically discloses a hydroxyl iron catalyst and a preparation method thereof. A hydroxyl iron catalyst comprises a carrier component and a catalytic component; the carrier component comprises the following raw materials in parts by weight: 50-80 parts of calcium silicate; 15-20 parts of fly ash; 10-15 parts of volcanic rock ash; 5-10 parts of mineral powder; 5-10 parts of bauxite; 5-10 parts of perlite powder; 10-20 parts of titanium dioxide sol; 10-20 parts of polytetrafluoroethylene dispersion; the catalytic component comprises the following raw materials in parts by weight: 50-60 parts of modified hydroxyl iron; 10-20 parts of copper oxide; 10-20 parts of manganese dioxide; the modified hydroxyl iron is obtained by modifying the hydroxyl iron with a rare earth nitrate solution. The hydroxyl iron catalyst of the present application can be used in the fields of urban water supply sterilization and disinfection, industrial wastewater treatment, etc., and has the advantages of strong catalytic effect and high mass transfer efficiency.

Description

Technical Field

[0001] The present application relates to the field of catalyst technology, and more specifically, to an iron oxyhydroxide catalyst and a preparation method thereof. Background Art

[0002] The application of ozone oxidation technology in the field of water treatment includes sterilization and disinfection of urban water supply and deep treatment of industrial wastewater. At present, this technology has received more and more attention in the treatment of organic wastewater, especially difficult-to-biodegrade organic wastewater. However, due to its oxidation selectivity and low ozone utilization rate, the promotion and application of ozone oxidation technology has been severely restricted. Ozone catalytic oxidation technology introduces a catalyst into the traditional single ozone system to increase the oxidation potential of ozone in the system and accelerate the production of hydroxyl radicals, an active species with stronger oxidation ability than ozone molecules, to achieve the purpose of rapid removal of organic pollutants. Ozone catalytic technology is considered to have the greatest application potential in sewage treatment applications due to its rapid oxidation and degradation of organic matter and low treatment cost.

[0003] In related technologies, iron oxyhydroxide (FeOOH), as an important inorganic functional material, has shown great application potential in the field of catalysis due to its unique physical and chemical properties, such as good adsorption performance, high specific surface area and abundant surface hydroxyl groups. In particular, in ozone catalytic oxidation technology, iron oxyhydroxide can not only effectively promote the decomposition of ozone to produce hydroxyl radicals, but also enhance the capture and degradation of organic pollutants through its surface adsorption, thereby significantly improving the oxidation efficiency of ozone and the removal rate of organic matter.

[0004] However, despite the excellent performance of iron oxyhydroxide catalysts in ozone catalytic oxidation technology, they still face many challenges in practical application. A key technical issue is that suspended matter and colloidal substances in wastewater may clog the pore structure of the catalyst carrier. The attachment and accumulation of these tiny particles will reduce the effective active sites of the catalyst, hinder the effective contact between ozone molecules and pollutant molecules, thereby reducing the mass transfer efficiency of the catalyst and severely weakening the catalytic effect. Summary of the invention

[0005] In order to enhance the catalytic effect of an iron oxyhydroxide catalyst, the present application provides an iron oxyhydroxide catalyst and a preparation method thereof.

[0006] The present application provides an iron oxyhydroxide catalyst using the following technical solution:

[0007] An iron oxyhydroxide catalyst comprises a carrier component and a catalytic component;

[0008] The carrier component includes the following raw materials in parts by weight:

[0009] Calcium silicate 50-80 parts;

[0010] 15-20 parts of fly ash;

[0011] 10-15 parts of volcanic ash;

[0012] 5-10 parts of mineral powder;

[0013] 5-10 parts of bauxite;

[0014] 5-10 parts of perlite powder;

[0015] 10-20 parts of titanium dioxide sol;

[0016] 10-20 parts of polytetrafluoroethylene dispersion;

[0017] The catalytic component comprises the following raw materials in parts by weight:

[0018] 50-60 parts of modified iron oxyhydroxide;

[0019] 10-20 parts of copper oxide;

[0020] 10-20 parts of manganese dioxide;

[0021] The modified oxyhydroxide iron is obtained by modifying the oxyhydroxide iron with a rare earth nitrate solution.

[0022] By adopting the above technical scheme, in terms of the carrier, calcium silicate has good chemical stability and certain adsorption properties, which can provide a stable skeleton structure for the entire carrier, enhance the mechanical strength of the catalyst, and make it not easy to be damaged in the complex environment of wastewater treatment. The components such as fly ash, volcanic rock ash, mineral powder, bauxite and perlite powder cooperate with each other to form a rich and diverse pore structure, which not only ensures sufficient specific surface area to load catalytic components, but also provides a good diffusion channel for ozone molecules and pollutant molecules. Titanium dioxide has photocatalytic properties and can produce free radicals with strong oxidizing properties under light conditions, which can decompose organic matter attached to the pores of the carrier and prevent pore blockage. Polytetrafluoroethylene has excellent hydrophobicity and anti-pollution properties, which can reduce the attachment of suspended matter and colloidal substances on the surface of the carrier, keep the surface of the carrier clean, and ensure that ozone molecules and pollutant molecules can smoothly contact the catalytic active sites.

[0023] In terms of catalytic components, modified oxyhydroxide iron is the core. Modified by rare earth nitrate solution, the surface oxygen vacancy concentration is increased, the ozone decomposition ability is enhanced, and ozone can be more efficiently converted into hydroxyl radicals with strong oxidizing properties, accelerating the decomposition of pollutants. Copper oxide and manganese dioxide, as auxiliary catalytic components, work synergistically with modified oxyhydroxide iron to further improve the catalyst's ability to treat different types of pollutants and broaden the catalyst's scope of application. Overall, the overall catalytic effect of the catalyst has been significantly enhanced, which can more effectively treat wastewater and improve wastewater treatment efficiency and quality.

[0024] From a microscopic perspective, during the mixing, molding and roasting process of raw materials such as calcium silicate and fly ash, atoms and molecules interact with each other to form a carrier with a certain crystal structure and pore structure. The size and distribution of these pores determine the specific surface area and mass transfer performance of the catalyst. Under light, the electrons in the valence band of titanium dioxide are excited to jump to the conduction band, generating electron-hole pairs. Holes have strong oxidizing properties and can react with water molecules adsorbed on the surface of the catalyst to generate hydroxyl radicals. These hydroxyl radicals can oxidize and decompose organic matter attached to the surface and in the pores into small molecules, thereby preventing the accumulation of organic matter. The molecular structure of polytetrafluoroethylene contains a large number of fluorine atoms, which are very electronegative, making the surface of polytetrafluoroethylene have extremely low surface energy. This low surface energy makes it difficult for suspended matter and colloidal substances to adhere to its surface. Even if a small amount of matter is attached, it is easily washed away by the water flow, thereby keeping the surface and pores of the carrier unobstructed.

[0025] The rare earth elements introduced into the modified oxyhydroxide can change its crystal structure and electronic state, and increase the number of surface oxygen vacancies. Ozone molecules are easily adsorbed on these oxygen vacancies and decompose to generate hydroxyl radicals. The presence of copper oxide and manganese dioxide can adjust the electron cloud density on the catalyst surface, promote the electron transfer process, and increase the rate of the catalytic reaction.

[0026] Optionally, the modified iron oxyhydroxide is prepared by the following method:

[0027] A. Mix the rare earth salt solution and the ferric nitrate solution, and stir at a speed of 300-500 r / min for 15-30 min to obtain a mixed solution;

[0028] B. Add sodium hydroxide solution to the mixed solution, stir at a speed of 500-800 r / min, adjust the pH value of the mixed solution to 9-11, control the dropping speed at 1-2 mL / min, add 0.2-0.5 mol of aluminum triisopropoxide after the dropwise addition is complete, and continue stirring the reaction for 1-2 h to obtain a suspension;

[0029] C. Allow the suspension to stand at room temperature for 12-23 hours, then centrifuge to obtain a precipitate, wash the precipitate, place the washed precipitate in a constant temperature drying oven, dry it at 80-100°C for 12-24 hours to obtain a dry precursor powder, place the dried precursor powder in a muffle furnace, heat it to 300-500°C at a heating rate of 2-5°C / min, and calcine it for 2-4 hours to obtain modified oxyhydroxide iron.

[0030] By adopting the above technical scheme, in the mixed solution stage, the rare earth salt solution and the ferric nitrate solution are stirred and mixed at a specific speed to ensure that the rare earth elements can be evenly dispersed in the solution. This lays the foundation for the subsequent full combination of rare earth elements and iron elements. During the precipitation reaction, the stirring speed, pH value, drop rate and reaction time are strictly controlled so that the rare earth elements can be accurately doped into the crystal structure of ferric hydroxide. The addition of aluminum triisopropoxide is a key step, which can promote the deposition and adsorption of rare earth metal ions on ferric hydroxide, increase the loading amount of rare earth elements, and thus significantly improve the catalytic activity of modified ferric hydroxide. Aluminum triisopropoxide can be hydrolyzed in the solution to produce aluminum hydroxide colloid, which has a large specific surface area and adsorption performance, can adsorb rare earth metal ions, and carry them to the surface of ferric hydroxide. In the subsequent reaction process, the rare earth metal ions gradually combine with ferric hydroxide to form a stable structure. The aging process allows the particles of the precipitate to grow and homogenize further, improving the integrity and stability of the crystal. Subsequent processing steps such as centrifugation, washing, drying and roasting remove impurities and moisture, giving the modified oxyhydroxide iron a suitable crystal structure and surface properties. The surface oxygen vacancy concentration of the modified oxyhydroxide iron prepared in this way is greatly increased, which can decompose ozone more efficiently and produce more hydroxyl radicals, thereby enhancing the ability to oxidize and decompose pollutants. Compared with unmodified oxyhydroxide iron, its catalytic efficiency and stability have been significantly improved, and it can maintain good performance in more complex wastewater treatment environments.

[0031] Optionally, the concentration of the rare earth salt solution is 0.1-0.5 mol / L; the rare earth salt solution includes any one of cerium nitrate, lanthanum nitrate and praseodymium nitrate.

[0032] By adopting the above technical scheme, any one of cerium nitrate, lanthanum nitrate and praseodymium nitrate is selected as a rare earth salt because these rare earth elements have unique electronic structures and chemical properties. Their outer electron orbits can interact with the iron ions in the oxyhydroxide, change the electron cloud distribution and crystal structure of the oxyhydroxide, and thus increase the concentration of surface oxygen vacancies. The appropriate rare earth salt concentration (0.1-0.5 mol / L) can ensure the appropriate loading of rare earth elements in the oxyhydroxide. If the concentration is too low, the amount of rare earth elements introduced is insufficient, and the catalytic activity of the oxyhydroxide cannot be significantly improved, resulting in limited performance improvement of the catalyst in ozone decomposition and pollutant oxidation. If the concentration is too high, it may cause the rare earth elements to aggregate excessively on the surface of the oxyhydroxide, forming agglomerates, reducing the number of active sites, and reducing the catalytic effect. By limiting the appropriate concentration and type, the prepared modified oxyhydroxide can give full play to the advantages of rare earth elements, improve the overall performance of the catalyst, and make it show higher efficiency and stability in wastewater treatment.

[0033] Optionally, the concentration of the ferric nitrate is 0.2-0.8 mol / L.

[0034] By adopting the above technical scheme, in the precipitation reaction, the iron ions in the ferric nitrate react with the hydroxide ions in the sodium hydroxide to generate ferric hydroxide precipitation. The concentration of ferric nitrate directly determines the concentration of the iron ions in the solution, thereby affecting the speed of the precipitation reaction and the size of the precipitated particles. When the concentration of ferric nitrate is 0.2-0.8mol / L, the iron ions react with the hydroxide ions at a suitable speed to form uniform small-particle ferric hydroxide precipitation. The small-particle precipitation has a large specific surface area, can provide more adsorption sites for rare earth ions, and is conducive to the uniform doping of rare earth elements into the ferric hydroxide structure. In the subsequent roasting process, the small-particle precipitation can interact more fully with the rare earth elements to form a modified oxyhydroxide iron with high catalytic activity, which promotes the decomposition of ozone and the oxidation reaction of pollutants.

[0035] Optionally, the rare earth salt solution and the ferric nitrate solution are mixed in a volume ratio of 1:3.

[0036] By adopting the above technical solution, when the volume ratio is 1:3, the ratio of rare earth ions to iron ions just meets the requirements for forming a stable structure during the precipitation reaction and subsequent modification process. During the precipitation process, rare earth ions and iron ions will precipitate together to form hydroxide precipitates, and the appropriate ratio allows the rare earth ions to be evenly distributed in the iron hydroxide precipitate. During the roasting process, the evenly distributed rare earth ions can better interact with iron ions, change the crystal structure and electronic properties of iron hydroxide, and increase the concentration of surface oxygen vacancies. The increase in surface oxygen vacancies is conducive to the adsorption and decomposition of ozone molecules, thereby improving the ozone decomposition ability and catalytic activity of the catalyst.

[0037] The present application also provides a method for preparing an iron oxyhydroxide catalyst, which adopts the following technical scheme:

[0038] A method for preparing an iron oxyhydroxide catalyst comprises the following steps:

[0039] S1, calcium silicate, fly ash, volcanic rock ash, mineral powder, bauxite, and perlite powder are mixed according to a ratio to obtain a mixture, 40-70wt% of deionized water based on the total weight of the mixture is added, the mixture is stirred evenly, and then formed, and carrier particles are obtained by drying and calcining;

[0040] S2, spraying titanium dioxide sol onto the carrier particles, drying and sintering, then immersing the carrier particles coated with titanium dioxide in a polytetrafluoroethylene dispersion, taking out and drying, and sintering at 300-400° C. for 1-2 hours, so that the polytetrafluoroethylene is evenly coated on the surface of the carrier particles;

[0041] S3, mixing modified ferric oxyhydroxide, copper oxide and manganese dioxide according to a proportion, adding deionized water and stirring evenly to obtain a catalytic component slurry;

[0042] S4, uniformly impregnating or spraying the catalyst component slurry onto the carrier particles, and obtaining the iron oxyhydroxide catalyst after drying and calcining.

[0043] By adopting the above technical scheme, in the preparation process of the carrier particles, the mixing of multiple raw materials makes them interact with each other during the molding and roasting process, undergoing physical and chemical changes, and forming a structure with a certain porosity and strength. Under light, the electron-hole pairs generated by the electron transition of titanium dioxide react with the surrounding water molecules and oxygen to generate hydroxyl radicals and superoxide anion radicals with strong oxidizing properties. These free radicals can oxidize and decompose organic matter attached to the surface and pores of the carrier into carbon dioxide and water. The fluorine atoms in the polytetrafluoroethylene molecules have strong electronegativity, which makes the intermolecular force small and the surface energy low, thereby showing excellent hydrophobicity and anti-pollution properties. After the catalytic component slurry is impregnated or sprayed onto the carrier particles, during the drying and roasting process, the active ingredients in the catalytic component are chemically bonded to the surface of the carrier and tightly combined. In the catalytic reaction, ozone molecules and pollutant molecules diffuse to the catalytic active sites through the pores of the carrier, and oxidative decomposition reactions occur under the action of the catalytic components to achieve the purification of sewage and wastewater.

[0044] Optionally, the drying temperature in S1 is 80-120° C., and the drying time is 2-6 hours; the roasting temperature is 400-600° C., and the roasting time is 2-4 hours.

[0045] Optionally, the solid content of the catalytic component slurry in S3 is 20-40wt%.

[0046] Optionally, the dipping or spraying in S4 is performed 1-3 times, and each dipping or spraying is followed by drying at 80-120° C. for 1-3 h, and finally calcining at 300-500° C. for 2-4 h.

[0047] In summary, this application has the following beneficial effects:

[0048] 1. In terms of the carrier of the catalyst of this application, calcium silicate, fly ash, volcanic rock ash, mineral powder, bauxite and perlite powder cooperate with each other to form a rich and diverse pore structure. Calcium silicate provides a stable skeleton, enhances the mechanical strength of the catalyst, and makes it not easy to be damaged in a complex wastewater environment; other raw materials jointly ensure sufficient specific surface area to load the catalytic components, and also provide a good diffusion channel for ozone molecules and pollutant molecules. The addition of titanium dioxide sol and polytetrafluoroethylene dispersion further improves the performance of the carrier. Titanium dioxide produces strong oxidizing free radicals under light, which can decompose organic matter in the pores of the carrier and prevent pore blockage; polytetrafluoroethylene has excellent hydrophobicity and anti-pollution properties, can reduce the attachment of suspended matter and colloidal substances, keep the surface of the carrier clean, and ensure that ozone and pollutant molecules effectively contact the active sites. In terms of catalytic components, modified oxyhydroxide iron is the core. Modified by rare earth nitrate solution, the surface oxygen vacancy concentration is increased, the ozone decomposition ability is enhanced, and ozone can be efficiently converted into hydroxyl radicals to accelerate the decomposition of pollutants. Copper oxide and manganese dioxide act as auxiliary catalytic components, synergistically with modified iron oxyhydroxide to broaden the catalyst's treatment range for different types of pollutants. Overall, the catalyst provided in this application can effectively cope with the challenges in wastewater treatment and significantly enhance the catalytic effect.

[0049] 2. In the process of preparing modified ferric hydroxide, the application stirs and mixes rare earth salt solution and ferric nitrate solution at a specific speed to ensure that rare earth elements are evenly dispersed, laying the foundation for subsequent combination. During the precipitation reaction, the stirring speed, pH value, drop rate and reaction time are strictly controlled so that rare earth elements are accurately doped into the ferric hydroxide crystalline structure. The addition of aluminum triisopropoxide promotes the deposition and adsorption of rare earth metal ions and increases the rare earth element loading. The steps of aging, centrifugation, washing, drying and roasting remove impurities and moisture, so that the modified ferric hydroxide has a suitable crystal structure and surface properties, greatly improves the surface oxygen vacancy concentration, enhances the decomposition ability of ozone and the oxidation decomposition ability of pollutants, thereby effectively enhancing the catalytic effect of the catalyst.

[0050] 3. By mixing and molding a variety of raw materials and preparing carrier particles by roasting, the catalytic component slurry is impregnated or sprayed onto the carrier particles, and after steps such as drying and roasting, a high-performance iron oxyhydroxide catalyst is successfully prepared. This method is not only simple in process and easy to operate, but also can accurately control the composition and structure of the catalyst, thereby ensuring its excellent catalytic performance. In addition, by adjusting various parameters in the preparation process, such as drying temperature, roasting temperature and time, the performance of the catalyst can be further optimized to meet different wastewater treatment needs. Therefore, the method of the present application has broad application prospects and important practical value. DETAILED DESCRIPTION

[0051] The present application is further described in detail below with reference to the embodiments.

[0052] Preparation Example of Modified Iron Oxyhydroxide

[0053] Preparation Example 1

[0054] Modified iron oxyhydroxide is prepared by the following method:

[0055] A. Mix 500 mL of 0.1 mol / L cerium nitrate solution and 1500 mL of 0.2 mol / L ferric nitrate solution, and stir at 300 r / min for 15 min to obtain a mixed solution;

[0056] B. Add 0.05 mol / L sodium hydroxide solution to the mixed solution, stir at a speed of 500 r / min, adjust the pH value of the mixed solution to 9-11, control the dropping speed at 1-2 mL / min, add 0.2 mol aluminum triisopropoxide after the dropwise addition is complete, and continue stirring the reaction for 1 h to obtain a suspension;

[0057] C. Allow the suspension to stand at room temperature for 12 hours, then centrifuge to obtain a precipitate, wash the precipitate, place the washed precipitate in a constant temperature drying oven, dry it at 80°C for 12 hours to obtain a dry precursor powder, place the dried precursor powder in a muffle furnace, heat it to 300°C at a heating rate of 2°C / min, and calcine for 2 hours to obtain modified oxyhydroxide iron.

[0058] Preparation Example 2

[0059] Modified iron oxyhydroxide is prepared by the following method:

[0060] A. Mix 500 mL of 0.3 mol / L lanthanum nitrate solution and 1500 mL of 0.5 mol / L ferric nitrate solution, and stir at 400 r / min for 25 min to obtain a mixed solution;

[0061] B. Add 0.05 mol / L sodium hydroxide solution to the mixed solution, stir at 700 r / min, adjust the pH value of the mixed solution to 9-11, control the dropping speed at 1-2 mL / min, add 0.35 mol aluminum triisopropoxide after the dropwise addition is complete, and continue stirring the reaction for 1.5 h to obtain a suspension;

[0062] C. Allow the suspension to stand at room temperature for 18 hours, then centrifuge to obtain a precipitate, wash the precipitate, place the washed precipitate in a constant temperature drying oven, dry it at 90°C for 18 hours to obtain a dry precursor powder, place the dried precursor powder in a muffle furnace, heat it to 400°C at a heating rate of 4°C / min, and calcine for 3 hours to obtain modified oxyhydroxide iron.

[0063] Preparation Example 3

[0064] Modified iron oxyhydroxide is prepared by the following method:

[0065] A. Mix 500 mL of a 0.5 mol / L praseodymium nitrate solution with 1500 mL of a 0.8 mol / L ferric nitrate solution, and stir at a speed of 500 r / min for 30 min to obtain a mixed solution;

[0066] B. Add 0.05 mol / L sodium hydroxide solution to the mixed solution, stir at 800 r / min, adjust the pH value of the mixed solution to 9-11, control the dropping speed at 1-2 mL / min, add 0.5 mol aluminum triisopropoxide after the dropwise addition is complete, and continue stirring and reacting for 2 h to obtain a suspension;

[0067] C. Allow the suspension to stand at room temperature for 23 hours, then centrifuge to obtain a precipitate, wash the precipitate, place the washed precipitate in a constant temperature drying oven, dry it at 100°C for 24 hours to obtain a dry precursor powder, place the dried precursor powder in a muffle furnace, heat it to 500°C at a heating rate of 5°C / min, and calcine for 4 hours to obtain modified oxyhydroxide iron.

[0068] Preparation Example 4

[0069] The modified iron oxyhydroxide is different from Preparation Example 3 in that aluminum triisopropoxide is not added in step B. The specific preparation steps are as follows:

[0070] A. Mix 500 mL of a 0.5 mol / L praseodymium nitrate solution with 1500 mL of a 0.8 mol / L ferric nitrate solution, and stir at a speed of 500 r / min for 30 min to obtain a mixed solution;

[0071] B. Add 0.05 mol / L sodium hydroxide solution to the mixed solution, stir at 800 r / min, adjust the pH value of the mixed solution to 9-11, control the dropping speed at 1-2 mL / min, and continue stirring and reacting for 2 h after the dropwise addition is completed to obtain a suspension;

[0072] C. Allow the suspension to stand at room temperature for 23 hours, then centrifuge to obtain a precipitate, wash the precipitate, place the washed precipitate in a constant temperature drying oven, dry it at 100°C for 24 hours to obtain a dry precursor powder, place the dried precursor powder in a muffle furnace, heat it to 500°C at a heating rate of 5°C / min, and calcine for 4 hours to obtain modified oxyhydroxide iron.

[0073] Preparation Example 5

[0074] The difference between the modified ferric oxyhydroxide and Preparation Example 3 is that the concentration of the praseodymium nitrate solution in step A is 0.01 mol / L.

[0075] Example

[0076] Example 1

[0077] A hydroxyl iron catalyst comprises a carrier component and a catalytic component. The raw material components and amounts of the carrier component and the catalytic component are shown in Table 1. In this embodiment, the solvent of the titanium dioxide sol is water, and the mass concentration of the titanium dioxide sol is 10%; the solvent of the polytetrafluoroethylene dispersion in this embodiment is water, and the mass concentration of the polytetrafluoroethylene dispersion is 35%; the modified hydroxyl iron is the modified hydroxyl iron prepared in Preparation Example 1.

[0078] An iron oxyhydroxide catalyst is prepared by the following method:

[0079] S1. Calcium silicate, fly ash, volcanic rock ash, mineral powder, bauxite and perlite powder are mixed according to a ratio to obtain a mixture, 40 wt% of deionized water based on the total weight of the mixture is added, the mixture is stirred evenly and then formed, dried at 80° C. for 2 h, and then calcined at 400° C. for 2 h to obtain carrier particles;

[0080] S2, spraying the titanium dioxide sol onto the carrier particles, taking out and drying, and sintering at 400° C. for 1 hour, then immersing the carrier particles coated with titanium dioxide in a polytetrafluoroethylene dispersion, taking out and drying, and sintering at 300° C. for 1 hour, so that the polytetrafluoroethylene is evenly coated on the surface of the carrier particles;

[0081] S3, mixing modified ferric oxyhydroxide, copper oxide and manganese dioxide according to a ratio, adding 280 g of deionized water and stirring evenly to obtain a catalytic component slurry;

[0082] S4. Spray the catalytic component slurry onto the carrier particles for 3 times. Dry at 80° C. for 1 hour after each immersion or spraying. After spraying, calcine at 300° C. for 2 hours to obtain the iron oxyhydroxide catalyst.

[0083] Example 2

[0084] A hydroxyl iron catalyst comprises a carrier component and a catalytic component. The raw material components and amounts of the carrier component and the catalytic component are shown in Table 1. In this embodiment, the solvent of the titanium dioxide sol is water, and the mass concentration of the titanium dioxide sol is 12%; the solvent of the polytetrafluoroethylene dispersion in this embodiment is water, and the mass concentration of the polytetrafluoroethylene dispersion is 37%; the modified hydroxyl iron is the modified hydroxyl iron prepared in Preparation Example 2.

[0085] An iron oxyhydroxide catalyst is prepared by the following method:

[0086] S1. Calcium silicate, fly ash, volcanic rock ash, mineral powder, bauxite and perlite powder are mixed according to a proportion to obtain a mixture, 50 wt% of deionized water based on the total weight of the mixture is added, the mixture is stirred evenly and then formed, dried at 100° C. for 4 h, and then calcined at 500° C. for 3 h to obtain carrier particles;

[0087] S2, spraying the titanium dioxide sol onto the carrier particles, taking out and drying, and sintering at 500° C. for 2 hours, then immersing the carrier particles coated with titanium dioxide in a polytetrafluoroethylene dispersion, taking out and drying, and sintering at 350° C. for 1.5 hours, so that the polytetrafluoroethylene is evenly coated on the surface of the carrier particles;

[0088] S3, mixing the modified ferric oxyhydroxide, copper oxide and manganese dioxide according to a ratio, adding 200 g of deionized water and stirring evenly to obtain a catalytic component slurry;

[0089] S4. Spray the catalytic component slurry onto the carrier particles for 3 times. Dry at 100° C. for 2 h after each immersion or spraying. After spraying, calcine at 400° C. for 3 h to obtain the iron oxyhydroxide catalyst.

[0090] Example 3

[0091] A hydroxyl iron catalyst comprises a carrier component and a catalytic component. The raw material components and amounts of the carrier component and the catalytic component are shown in Table 1. In this embodiment, the solvent of the titanium dioxide sol is water, and the mass concentration of the titanium dioxide sol is 15%; the solvent of the polytetrafluoroethylene dispersion in this embodiment is water, and the mass concentration of the polytetrafluoroethylene dispersion is 40%; the modified hydroxyl iron is the modified hydroxyl iron prepared in Preparation Example 3.

[0092] An iron oxyhydroxide catalyst is prepared by the following method:

[0093] S1. Calcium silicate, fly ash, volcanic rock ash, mineral powder, bauxite and perlite powder are mixed according to a proportion to obtain a mixture, 70 wt% of deionized water based on the total weight of the mixture is added, the mixture is stirred evenly and then formed, dried at 120° C. for 6 h, and then calcined at 600° C. for 4 h to obtain carrier particles;

[0094] S2, spraying the titanium dioxide sol onto the carrier particles, taking out and drying, and sintering at 600° C. for 3 hours, then immersing the carrier particles coated with titanium dioxide in a polytetrafluoroethylene dispersion, taking out and drying, and sintering at 400° C. for 2 hours, so that the polytetrafluoroethylene is evenly coated on the surface of the carrier particles;

[0095] S3, mixing modified ferric oxyhydroxide, copper oxide and manganese dioxide according to a ratio, adding 150 g of deionized water and stirring evenly to obtain a catalytic component slurry;

[0096] S4. Spray the catalytic component slurry onto the carrier particles for 3 times. After each dipping or spraying, dry at 120° C. for 3 hours. After spraying, calcine at 500° C. for 4 hours to obtain the iron oxyhydroxide catalyst.

[0097] Table 1 Raw material components and amounts of Examples 1-3 (g)

[0098]

[0099] Example 4

[0100] A hydroxyl iron catalyst, which is different from Example 1 in that the modified hydroxyl iron in this example is the modified hydroxyl iron prepared in Preparation Example 4.

[0101] Example 5

[0102] A ferric oxyhydroxide catalyst, which is different from Example 1 in that the modified ferric oxyhydroxide in this example is the modified ferric oxyhydroxide prepared in Preparation Example 5.

[0103] Comparative Example

[0104] Comparative Example 1

[0105] A ferric oxyhydroxide catalyst is different from Example 1 in that titanium dioxide sol is not added to the carrier component of this comparative example; when preparing the catalyst, step S2 is not performed, and titanium dioxide sol is not sprayed on the carrier particles.

[0106] Comparative Example 2

[0107] A ferric oxyhydroxide catalyst is different from Example 1 in that no polytetrafluoroethylene dispersion is added to the carrier component of this comparative example; when preparing the catalyst, step S2 is not performed, and the carrier particles coated with titanium dioxide are not immersed in the polytetrafluoroethylene dispersion.

[0108] Comparative Example 3

[0109] A ferric oxyhydroxide catalyst, which is different from Example 1 in that an equal amount of unmodified ferric oxyhydroxide is used in the catalytic component of this comparative example instead of the modified ferric oxyhydroxide.

[0110] Performance testing

[0111] Test 1: Catalytic effect detection

[0112] Add simulated wastewater to the reactor (the simulated wastewater uses a solution containing phenol, with an initial concentration of 50 mg / L). Add 10g of catalyst and introduce ozone gas (the concentration is controlled at 10-20 mg / L, and the flow rate is 0.5 L / min). Take samples after 240 minutes, use HPLC to detect the pollutant concentration, and calculate the pollutant degradation rate. The higher the degradation rate, the better the catalytic effect of the catalyst. The results are shown in Table 2.

[0113] Test 2: Mass transfer efficiency test

[0114] 10g of catalyst was loaded into the reactor. Ozone gas (concentration controlled at 10-20mg / L) was introduced, and the gas flow rate was adjusted to 0.5L / min. The ozone concentration was measured at the reactor outlet using an ozone concentration detector to calculate the ozone mass transfer efficiency. The results are shown in Table 2.

[0115] Table 2 Test results

[0116]

[0117] Examples 1-3 of the present application use optimized carrier components (calcium silicate, fly ash, volcanic rock ash, etc.) and catalytic components (modified oxyhydroxide iron, copper oxide, manganese dioxide), and further improve the carrier performance through titanium dioxide sol and polytetrafluoroethylene dispersion. The modified oxyhydroxide iron is modified by rare earth elements to increase the surface oxygen vacancy concentration, enhance the ozone decomposition ability and pollutant degradation efficiency. Titanium dioxide sol produces strong oxidizing free radicals under light to prevent pore blockage; the hydrophobicity of polytetrafluoroethylene dispersion reduces the attachment of suspended matter and keeps the carrier surface clean. Therefore, Examples 1-3 show a high degradation rate and mass transfer efficiency, so the catalyst has a good catalytic effect.

[0118] In Example 4, aluminum triisopropoxide was not added, resulting in a lower rare earth element loading and a decrease in the surface oxygen vacancy concentration of the modified iron oxyhydroxide. Therefore, its degradation rate (93%) and mass transfer efficiency (88%) were slightly lower than those of Examples 1-3.

[0119] In Example 5, the concentration of the praseodymium nitrate solution is relatively low (0.01 mol / L), resulting in insufficient rare earth element doping and poor modification effect. Therefore, its degradation rate (90%) and mass transfer efficiency (85%) are further reduced.

[0120] Comparative Example 1 did not add titanium dioxide sol, which resulted in easy clogging of the carrier pores, reduced mass transfer efficiency, and significantly reduced degradation rate. Comparative Example 2 did not add polytetrafluoroethylene dispersion, which resulted in easy attachment of suspended matter to the carrier surface, reduced mass transfer efficiency, and reduced degradation rate. Comparative Example 3 used unmodified iron oxyhydroxide, which had a low surface oxygen vacancy concentration, and significantly reduced ozone decomposition ability and pollutant degradation efficiency.

[0121] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. An iron oxyhydroxide catalyst, characterized in that The invention comprises a carrier component and a catalytic component; the carrier component comprises the following raw materials in parts by weight: 50-80 parts of calcium silicate; 15-20 parts of fly ash; 10-15 parts of volcanic rock ash; 5-10 parts of mineral powder; 5-10 parts of bauxite; 5-10 parts of perlite powder; 10-20 parts of titanium dioxide sol; 10-20 parts of polytetrafluoroethylene dispersion; the catalytic component comprises the following raw materials in parts by weight: 50-60 parts of modified oxyhydroxide iron; 10-20 parts of copper oxide; 10-20 parts of manganese dioxide; the modified oxyhydroxide iron is prepared by the following method: A. Mixing a rare earth salt solution and a ferric nitrate solution, and stirring to obtain a mixed solution; B. Add sodium hydroxide solution to the mixed solution, stir, adjust the pH value of the mixed solution, add aluminum triisopropoxide, continue stirring and react to obtain a suspension; C. Allow the suspension to stand at room temperature for aging and then centrifuge to obtain a precipitate, wash and dry the precipitate to obtain a precursor powder, and calcine the dried precursor powder to obtain the product.

2. An iron oxyhydroxide catalyst according to claim 1, characterized in that The stirring in step A is specifically stirring at a speed of 300-500 r / min for 15-30 min; the stirring speed in step B is 500-800 r / min, the pH value is 9-11, and the dropping speed of the sodium hydroxide solution is 1-2 mL / min; the standing aging time in step C is 12-23 h, the drying is specifically drying at 80-100 ° C for 12-24 h, and the roasting is specifically heating to 300-500 ° C at a heating rate of 2-5 ° C / min and roasting for 2-4 h.

3. The iron oxyhydroxide catalyst according to claim 1, characterized in that: The concentration of the rare earth salt solution is 0.1-0.5 mol / L; the rare earth salt solution includes any one of cerium nitrate, lanthanum nitrate and praseodymium nitrate.

4. The iron oxyhydroxide catalyst according to claim 1, characterized in that: The concentration of the ferric nitrate is 0.2-0.8 mol / L.

5. The iron oxyhydroxide catalyst according to claim 1, characterized in that: The volume ratio of the rare earth salt solution to the ferric nitrate solution is 1:

3.

6. A method for preparing the iron oxyhydroxide catalyst according to any one of claims 1 to 5, characterized in that: The steps include: S1, calcium silicate, fly ash, volcanic rock ash, mineral powder, bauxite, and perlite powder are mixed according to a ratio to obtain a mixture, 40-70wt% of deionized water based on the total weight of the mixture is added, the mixture is stirred evenly, and then formed, and carrier particles are obtained by drying and calcining; S2, spraying titanium dioxide sol onto the carrier particles, drying and sintering, then immersing the carrier particles coated with titanium dioxide in a polytetrafluoroethylene dispersion, taking out and drying, and sintering at 300-400° C. for 1-2 hours, so that the polytetrafluoroethylene is evenly coated on the surface of the carrier particles; S3, mixing modified ferric oxyhydroxide, copper oxide and manganese dioxide according to a proportion, adding deionized water and stirring evenly to obtain a catalytic component slurry; S4. Uniformly impregnate or spray the catalyst component slurry onto the carrier particles, and obtain the iron oxyhydroxide catalyst after drying and calcining.

7. The method for preparing an iron oxyhydroxide catalyst according to claim 6, characterized in that: The drying temperature in S1 is 80-120° C., and the drying time is 2-6 hours; the calcining temperature is 400-600° C., and the calcining time is 2-4 hours.

8. The method for preparing an iron oxyhydroxide catalyst according to claim 6, characterized in that: The solid content of the catalytic component slurry in S3 is 20-40wt%.

9. The method for preparing an iron oxyhydroxide catalyst according to claim 6, characterized in that: The dipping or spraying in S4 is performed 1-3 times, and each dipping or spraying is followed by drying at 80-120° C. for 1-3 hours, and finally calcining at 300-500° C. for 2-4 hours.

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