Organic-inorganic composite photocatalytic porous material and preparation method thereof

Abstract

The invention discloses an organic-inorganic composite photocatalytic porous material and a preparation method thereof, and belongs to the technical field of photocatalytic waste gas treatment.The preparation method comprises the steps that silicon carbide nanowires are subjected to amination treatment and compounded with graphene oxide dispersion liquid, and graphene oxide / silicon carbide aerogel is obtained in the presence of a surfactant under the acidic condition; preparing an iron complexing solution, synthesizing a titanium-based MOF precursor through a solvothermal method, adding an iron complex, and loading the graphene oxide / silicon carbide aerogel to obtain organic-inorganic composite aerogel; mixing and stirring a calcium nitrate solution, trisodium citrate and a monopotassium phosphate solution, then adding the organic-inorganic composite aerogel to obtain organic-inorganic composite powder, and carrying out surface hydrophobic treatment to obtain an organic-inorganic composite photocatalytic porous material; and high mechanical strength, high photocatalytic activity and strong corrosion resistance are realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of photocatalytic waste gas treatment, and particularly relates to an organic-inorganic composite photocatalytic porous material and a preparation method thereof. BACKGROUND

[0002] Photocatalytic porous materials have attracted extensive attention due to their unique structural characteristics and good photocatalytic performance. They are usually composed of elements such as titanium and are synthesized through specific preparation methods such as raw material selection, mixing, precipitation, calcination and surface treatment, and exhibit fast reaction rate, high product yield and good reaction stability in photocatalytic reactions.

[0003] Porous materials are materials with network structure composed of interconnected or closed pores, the boundaries or surfaces of which are composed of pillars or plates, which can be in the form of fine or coarse powder, pressed body, extruded body, sheet body or block body, and the pore shape and flowability are usually investigated, and the inner and outer surface areas are measured.

[0004] Photocatalytic porous materials refer to a class of semiconductor catalyst materials with porous structure, which can undergo photochemical reactions under the action of light, usually have large specific surface area and porosity, can effectively adsorb and disperse reactant molecules, thereby improving the efficiency of photocatalytic reaction. In the prior art, MOF is often added to prepare adsorbents because MOF has ultra-high specific surface area and adjustable pore size structure, can efficiently adsorb VOCs (such as benzene, formaldehyde, etc.) in waste gas, increase the local concentration of pollutants on the surface of the catalyst, and improve the efficiency of photocatalytic reaction.

[0005] Chinese patent application with publication number CN 118437274A discloses a preparation method of a high-adsorption-capacity adsorbent and the adsorbent. Coal and related products of coal are used as carbon source, and through processes such as carbonization activation, acid pickling, hot alkali treatment, an adsorbent material with relatively good adsorption performance is prepared. Although the coal-based material has large specific surface area, coal itself is a brittle material, and a large number of micropores formed after activation further weaken the continuity of the skeleton, which is easy to collapse under the impact of airflow, and may be corroded when facing corrosive gas environment, thereby shortening the service life and increasing the cost in actual application. SUMMARY

[0006] The present application aims to solve the problems of low efficiency and short service life caused by low mechanical properties and low corrosion resistance of photocatalytic porous materials in treating waste gas, and provides an organic-inorganic composite photocatalytic porous material and a preparation method thereof.

[0007] The object of the present application can be achieved by the following technical solutions:

[0008] A preparation method of an organic-inorganic composite photocatalytic porous material, comprising the following steps:

[0009] Step one: amino treatment is performed on the silicon carbide nanowires to obtain an amino silicon carbide nanowire dispersion liquid; the amino silicon carbide nanowire dispersion liquid is compounded with a graphene oxide dispersion liquid, and under the action of a surfactant and an acidic condition, a graphene oxide / silicon carbide aerogel is obtained.

[0010] Step two: an iron complex solution is prepared, a titanium-based MOF precursor is synthesized by a solvothermal method, the graphene oxide / silicon carbide aerogel is loaded after the addition of the iron complex, vacuum impregnation and freeze drying are performed, and an organic-inorganic composite aerogel is obtained.

[0011] Step three: a calcium nitrate solution, a trisodium citrate and a potassium dihydrogen phosphate solution are sequentially mixed and stirred in a reaction kettle, the pH value is adjusted, the organic-inorganic composite aerogel is added, hydrothermal reaction is performed, centrifugal drying is performed, and an organic-inorganic composite powder is obtained; surface modification is performed on the organic-inorganic composite powder, 1H, 1H, 2H, 2H-perfluorodecanethiol and triethylamine in an ethanol solvent, and washing and drying are performed, and an organic-inorganic composite photocatalytic porous material is obtained.

[0012] Further, the specific preparation steps of the graphene oxide / silicon carbide aerogel are as follows: the silicon carbide nanowires, ethanol and 3-aminopropyl triethoxysilane are added to a reaction kettle, reaction is performed at 80-90 DEG C for 8-10 h, and an amino silicon carbide nanowire dispersion liquid is obtained; 1wt% of the graphene oxide dispersion liquid and 1wt% of the amino silicon carbide nanowire dispersion liquid are stirred at 60-80 DEG C for 2-3 h, sodium dodecyl benzene sulfonate and acetic acid are added, reaction is performed at 120-150 DEG C for 2-4 h, and freeze drying is performed, and the graphene oxide / silicon carbide aerogel is obtained.

[0013] Further, the amount ratio of the silicon carbide nanowires, ethanol and 3-aminopropyl triethoxysilane is 3-5 g:600-1000 mL:30-50 mL; the amount ratio of the graphene oxide dispersion liquid, the amino silicon carbide nanowire dispersion liquid, sodium dodecyl benzene sulfonate and acetic acid is 600-1000 mL:600-1000 mL:0.6-0.8 g:0.18-0.22 g.

[0014] Furthermore, the specific preparation steps of the organic-inorganic composite aerogel are as follows: ethylene glycol, iron acetylacetonate and disodium ethylenediaminetetraacetate are added to a reactor, stirred at 60-80°C for 30-40 minutes to obtain an iron complex solution; titanium acetylacetonate and N,N-dimethylformamide are added to the reactor, ultrasonicated for 20-30 minutes, and then terephthalic acid is added, stirred for 2-3 hours, and reacted at 120-130°C for 6-8 hours, and then the iron complex solution is added, reacted at 120-140°C for 12-14 hours, and then graphene oxide / silicon carbide aerogel is added, vacuum soaked for 20-24 hours, and freeze-dried for 10-12 hours to obtain the organic-inorganic composite aerogel.

[0015] Furthermore, the usage ratio of ethylene glycol, ferric acetylacetonate and disodium ethylenediaminetetraacetate is 20-30 mL: 0.6-0.8 g: 0.5-0.7 g; the usage ratio of titanium acetylacetonate, N,N-dimethylformamide, terephthalic acid, iron complex solution and graphene oxide / silicon carbide aerogel is 0.85-0.95 mL: 80-90 mL: 150-170 mg: 20-30 mL: 3-5 g.

[0016] Furthermore, the specific preparation steps of the organic-inorganic composite powder are as follows: 1.5wt% calcium nitrate solution and trisodium citrate are added to a reactor, stirred for 30-40 minutes, 1.2wt% potassium dihydrogen phosphate solution is slowly added, stirred for 30-40 minutes, the pH value is adjusted to 7.8-8 with ammonia water, and then the organic-inorganic composite aerogel is added, stirred at 80-90°C for 2-3 hours, filtered, the filter cake is centrifuged, and dried to obtain the organic-inorganic composite powder.

[0017] Furthermore, the usage ratio of calcium nitrate solution, trisodium citrate, potassium dihydrogen phosphate solution and organic-inorganic composite aerogel is 100-120 mL: 3-5 g: 100-120 mL: 2-4 g.

[0018] Furthermore, the specific preparation steps of the organic-inorganic composite photocatalytic porous material are as follows: ethanol, organic-inorganic composite powder, 1H,1H,2H,2H-perfluorodecanethiol and triethylamine are added to a reactor, ultrasonicated at 50-70°C for 2-3 hours, filtered, the filter cake is washed with ethanol 3-5 times, and dried at 80-90°C for 3-4 hours to obtain an organic-inorganic composite photocatalytic porous material.

[0019] Furthermore, the usage ratio of ethanol, organic-inorganic composite powder, 1H,1H,2H,2H-perfluorodecanethiol and triethylamine is 1200-1400 mL: 2-4 g: 2-4 g: 0.8-1 g.

[0020] Beneficial effects of the present invention:

[0021] 1. The present invention uses an aerogel formed by amino-modified silicon carbide nanowires and graphene oxide as a substrate, loads iron / titanium MOF to promote photocatalytic separation, forms an aerogel with a high specific surface area, and in-situ deposits hydroxyapatite to form a coating to further enhance the structure. After hydrophobic treatment, the photocatalytic activity, pollutant adsorption capacity, reaction medium transmission efficiency, chemical stability and anti-pollution properties of the material are synergistically improved, and finally a multifunctional material with efficient light response, structural stability and environmental adaptability is obtained.

[0022] 2. In the present invention, silicon carbide nanowires are compounded with graphene oxide after amino treatment to form a three-dimensional aerogel skeleton under the surfactant, thereby improving the high specific surface area and strong mechanical strength of the material, solving the problem of easy collapse of traditional carriers, and at the same time, as a wide-bandgap semiconductor, promoting photocatalytic separation with graphene oxide, providing efficient electron transmission channels through the one-dimensional structure. After the surface is modified by amino, the interface bonding with graphene oxide, metal complex and mineral layer is enhanced, thereby greatly improving the specific surface area and transmission efficiency.

[0023] 3. The titanium MOF formed by titanium acetylacetonate and terephthalic acid in the present invention is a highly efficient photocatalytic center that can effectively absorb visible light and even ultraviolet light to generate strongly oxidizing photogenerated holes and reducing photogenerated electrons. The titanium MOF is composited with graphene oxide / silicon carbide aerogel. Graphene oxide and silicon carbide are both excellent semiconductor materials that can effectively promote the separation of photogenerated electron-hole pairs, greatly reduce the recombination rate, and significantly improve the quantum efficiency and catalytic activity.

[0024] 4. The iron acetylacetonate added in the present invention forms an iron complex, which is doped into the titanium MOF lattice or forms a catalytic site on its surface. The iron ion energy level can broaden the light response range and promote interfacial charge transfer, further improving the catalytic efficiency. The porous structure of the aerogel substrate and the final material provides a huge specific surface area and abundant active sites, which is conducive to the rapid diffusion and transmission of pollutant molecules and degradation products.

[0025] 5. In the present invention, a physical barrier is provided by in-situ deposition of a hydroxyapatite protective layer on the surface, which effectively isolates the corrosive medium from direct contact and erosion of the internal photoactive components, improves its chemical stability, and extends the service life of the material in harsh environments such as salt spray and water. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] Example 1

[0028] A preparation method of an organic-inorganic composite photocatalytic porous material, comprising the following steps:

[0029] Step one: 3 g of silicon carbide nanowires, 600 mL of ethanol and 30 mL of 3- aminopropyltriethoxysilane are added to a reaction kettle, and reacted at 80°C for 8 h to obtain an amino-silicon carbide nanowire dispersion liquid; 600 mL of 1% mass fraction of graphene oxide dispersion liquid and 600 mL of 1% mass fraction of amino-silicon carbide nanowire dispersion liquid are stirred at 60°C for 2 h, 0.6 g of sodium dodecyl benzene sulfonate and 0.18 g of acetic acid are added, and reacted at 120°C for 2 h, and then freeze-dried to obtain graphene oxide / silicon carbide aerogel.

[0030] The silicon carbide nanowires are modified by amination, electrostatic attraction occurs with oxygen-containing functional groups on the graphene oxide sheet, and under the action of surfactant-assisted dispersion and high temperature, the graphene oxide is partially reduced and self-assembled to form a three-dimensional network gel structure with the amino-silicon carbide nanowires, and after freeze-drying, the graphene oxide / silicon carbide aerogel is obtained; the silicon carbide nanowires and the covalently cross-linked network improve the mechanical strength of the aerogel, and the graphene sheet and the silicon carbide nanowires interpenetrate to form a porous structure, accelerating the diffusion and adsorption of waste gas.

[0031] Step two: 20 mL of ethylene glycol, 0.6 g of iron acetylacetonate and 0.5 g of disodium ethylenediaminetetraacetate are added to a reaction kettle, and stirred at 60°C for 30 min to obtain an iron complex solution;

[0032] 0.85 mL of titanium acetylacetonate and 80 mL of N,N-dimethylformamide are added to a reaction kettle, and ultrasonically treated for 20 min, then 150 mg of terephthalic acid is added, stirred for 2 h, reacted at 120°C for 6 h, then 20 mL of the iron complex solution is added, reacted at 120°C for 12 h, then 3 g of graphene oxide / silicon carbide aerogel is added, vacuum soaked for 20 h, and freeze-dried for 10 h to obtain an organic-inorganic composite aerogel.

[0033] The disodium ethylenediaminetetraacetate reduces the agglomeration of iron ions, and then constructs a titanium-based MOF crystal nucleus, and under high temperature, the iron ions are inserted to form Fe / Ti bimetallic nodes, vacuum soaking makes the MOF precursor deeply adsorbed in the pores of the graphene oxide / silicon carbide aerogel, freeze-drying retains the porous structure, and realizes the uniform anchoring of the MOF on the aerogel skeleton; the iron MOF can enhance the visible light absorption, and the titanium MOF provides high catalytic activity, and cooperatively improves the photocatalytic and waste gas separation efficiency.

[0034] Step three: 100 mL of 1.5% calcium nitrate solution and 3 g of trisodium citrate were added to the reaction kettle, stirred for 30 min, 100 mL of 1.2% potassium dihydrogen phosphate solution was slowly added, stirred for 30 min, the pH value was adjusted to 7.8 with ammonia water, and then 2 g of organic-inorganic composite aerogel was added. Stirring at 80℃ for 2h, filtering, centrifuging the filter cake, and drying to obtain an organic-inorganic composite powder.

[0035] By chelating calcium ions with trisodium citrate to inhibit rapid precipitation, and slowly generating nano calcium hydrogen phosphate with potassium dihydrogen phosphate in weak alkaline conditions, the calcium hydrogen phosphate is uniformly deposited on the surface of the MOF / aerogel through mild stirring at 80℃, forming a porous protective layer that is beneficial to block the acid / sulfur exhaust gas erosion and improve the chemical stability.

[0036] Step four: 1200 mL of ethanol, 2 g of organic-inorganic composite powder, 2 g of 1H, 1H, 2H, 2H-perfluorodecanethiol, and 0.8 g of triethylamine were added to the reaction kettle, ultrasonic treatment at 50℃ for 2h, filtering, washing the filter cake with ethanol for 3 times, and drying at 80℃ for 3h to obtain an organic-inorganic composite photocatalytic porous material.

[0037] Through the catalysis of triethylamine, the -SH group of 1H, 1H, 2H, 2H-perfluorodecanethiol forms a Ca-S bond with the calcium ions in the calcium hydrogen phosphate coating layer, and at the same time, the long fluorocarbon chain self-assembles on the surface of the material, constructing a super-hydrophobic barrier; the fluorocarbon chain forms a low surface energy layer to block the adsorption of oil mist, water vapor and particulate matter in the exhaust gas, avoiding the clogging of active sites, resisting acid rain and high humidity environment, and improving the service life of the material.

[0038] Example 2:

[0039] A preparation method of an organic-inorganic composite photocatalytic porous material, comprising the following steps:

[0040] Step one: 4 g of silicon carbide nanowires, 800 mL of ethanol, and 40 mL of 3-aminopropyl triethoxysilane were added to the reaction kettle, and reacted at 85℃ for 9h to obtain an amino-functionalized silicon carbide nanowire dispersion; 800 mL of 1% graphene oxide dispersion and 800 mL of 1% amino-functionalized silicon carbide nanowire dispersion were added to the reaction kettle, stirred at 70℃ for 2.5h, 0.7 g of sodium dodecyl benzene sulfonate and 0.20 g of acetic acid were added, and reacted at 135℃ for 3h. Freeze-drying to obtain graphene oxide / silicon carbide aerogel.

[0041] Step two: 25 mL of ethylene glycol, 0.7 g of acetylacetone iron, and 0.6 g of disodium ethylenediaminetetraacetate were added to the reaction kettle, and stirred at 70℃ for 35 min to obtain an iron complex solution.

[0042] Into a reaction kettle, 0.90 mL of titanium acetylacetonate and 85 mL of N,N-dimethylformamide were added, and ultrasonic treatment was performed for 25 min. Then, 160 mg of terephthalic acid was added, and stirring was performed for 2.5 h. Subsequently, reaction was performed at 125 ℃ for 7 h. Then, 25 mL of an iron complex solution was added, and reaction was performed at 130 ℃ for 13 h. Then, 4 g of graphene oxide / silicon carbide aerogel was added, vacuum soaking was performed for 22 h, and freeze drying was performed for 11 h to obtain an organic-inorganic composite aerogel.

[0043] Step three: Into a reaction kettle, 110 mL of a 1.5% by mass calcium nitrate solution and 4 g of trisodium citrate were added, and stirring was performed for 35 min. Then, 110 mL of a 1.2% by mass potassium dihydrogen phosphate solution was slowly added, and stirring was performed for 35 min. Then, the pH value was adjusted to 7.9 by using ammonia water. Then, 3 g of the organic-inorganic composite aerogel was added, and stirring was performed at 85 ℃ for 2.5 h. Then, filtration was performed, the filter cake was centrifuged, and drying was performed to obtain an organic-inorganic composite powder.

[0044] Step four: Into a reaction kettle, 1300 mL of ethanol, 3 g of the organic-inorganic composite powder, 3 g of 1H,1H,2H,2H-perfluorodecanethiol, and 0.9 g of triethylamine were added, and ultrasonic treatment was performed at 60 ℃ for 2.5 h. Then, filtration was performed, the filter cake was washed with ethanol for 4 times, and drying was performed at 85 ℃ for 3.5 h to obtain an organic-inorganic composite photocatalytic porous material.

[0045] Example 3:

[0046] A method for preparing an organic-inorganic composite photocatalytic porous material, comprising the following steps:

[0047] Step one: Into a reaction kettle, 5 g of silicon carbide nanowires, 1000 mL of ethanol, and 50 mL of 3-aminopropyltriethoxysilane were added, and reaction was performed at 90 ℃ for 10 h to obtain an aminated silicon carbide nanowire dispersion liquid. Then, 1000 mL of a 1% by mass graphene oxide dispersion liquid and 1000 mL of a 1% by mass aminated silicon carbide nanowire dispersion liquid were added, and stirring was performed at 80 ℃ for 3 h. Then, 0.8 g of sodium dodecylbenzenesulfonate and 0.22 g of acetic acid were added, and reaction was performed at 150 ℃ for 4 h. Then, freeze drying was performed to obtain graphene oxide / silicon carbide aerogel.

[0048] Step two: Into a reaction kettle, 30 mL of ethylene glycol, 0.8 g of iron acetylacetonate, and 0.7 g of disodium ethylenediaminetetraacetate were added, and stirring was performed at 80 ℃ for 40 min to obtain an iron complex solution.

[0049] Into a reaction kettle, 0.95 mL of titanium acetylacetonate and 90 mL of N,N-dimethylformamide were added, and ultrasonic treatment was performed for 30 min. Then, 170 mg of terephthalic acid was added, and stirring was performed for 3 h. Subsequently, reaction was performed at 130 DEG C for 8 h. Then, 30 mL of an iron complex solution was added, and reaction was performed at 140 DEG C for 14 h. Then, 5 g of graphene oxide / silicon carbide aerogel was added, vacuum soaking was performed for 24 h, and freeze-drying was performed for 12 h to obtain an organic-inorganic composite aerogel.

[0050] Step three: Into a reaction kettle, 120 mL of a 1.5% by mass calcium nitrate solution and 5 g of trisodium citrate were added, and stirring was performed for 40 min. Then, 120 mL of a 1.2% by mass potassium dihydrogen phosphate solution was slowly added, and stirring was performed for 40 min. Then, the pH value was adjusted to 8 by using ammonia water. Then, 4 g of the organic-inorganic composite aerogel was added, and stirring was performed at 90 DEG C for 3 h. Then, filtration was performed, the filter cake was centrifuged, and drying was performed to obtain an organic-inorganic composite powder.

[0051] Step four: Into a reaction kettle, 1400 mL of ethanol, 4 g of the organic-inorganic composite powder, 4 g of 1H, 1H, 2H, 2H-perfluorodecanethiol, and 1 g of triethylamine were added, and ultrasonic treatment was performed at 70 DEG C for 3 h. Then, filtration was performed, the filter cake was washed with ethanol for 5 times, and drying was performed at 90 DEG C for 4 h to obtain an organic-inorganic composite photocatalytic porous material.

[0052] The silicon carbide nanowires in Examples 1-3 were selected from Qinghe County Chaotai Metal Material Co., Ltd. (Chaotai); the graphene oxide was selected from Jiangxi Suobang New Material Technology Co., Ltd. (Suobang New Material); the acetylacetone iron and the acetylacetone titanium were selected from Hubei Xiyu Hong Biological Medicine Technology Co., Ltd. (xyh001); and the terephthalic acid was selected from Shandong Wangtong Chemical Co., Ltd. (wt-f655ghklo2).

[0053] Comparative Example 1: The difference from Example 1 is that, in Step one, no silicon carbide nanowires are added, and in Step two, the graphene oxide / silicon carbide aerogel is replaced by graphene oxide aerogel, and the remaining steps remain unchanged to prepare an organic-inorganic composite photocatalytic porous material.

[0054] Comparative Example 2: The difference from Example 1 is that, in Step two, no acetylacetone titanium is added to prepare an organic-inorganic composite aerogel, which replaces the organic-inorganic composite aerogel in Step three, and the remaining steps remain unchanged to prepare an organic-inorganic composite photocatalytic porous material.

[0055] Comparative Example 3: The difference from Example 1 is that, no Step three is performed, and the organic-inorganic composite powder in Step four is replaced by the organic-inorganic composite aerogel in Step two, and the remaining steps remain unchanged to prepare an organic-inorganic composite photocatalytic porous material.

[0056] The organic-inorganic composite photocatalytic porous materials prepared in Example 1-Example 3 and Comparative Example 1-Comparative Example 3 were immersed in methanol solution for 3 days, and fresh methanol solution was replaced twice a day. The solvent was removed by vacuum adsorption to obtain test samples. 80 mg of each test sample was subjected to nitrogen adsorption and desorption experiments by BET at a temperature of 77 K to calculate the specific surface area and mechanical strength. The VOCs tail gas treatment effect test was performed. The adsorption and catalytic removal rate = (VOCs tail gas concentration before adsorption and catalysis - concentration after adsorption and catalysis) / VOCs tail gas concentration before adsorption and catalysis x 100%. The sample coated with powder paint was placed in a salt spray test chamber with a temperature of 35°C and a salt solution concentration of 5%, and continuous spraying was performed. The time when corrosion (such as rusting, blistering, etc.) occurred on the sample was recorded to test the corrosion resistance.

[0057] The results are shown in Table 1:

[0058] Table 1: Performance test results of organic-inorganic composite photocatalytic porous materials

[0059]

[0060]

[0061] As can be seen from Table 1, the performance of the organic-inorganic composite photocatalytic porous materials in Example 1-Example 3 is significantly better than that in Comparative Example; by adding silicon carbide nanowires as a rigid skeleton in the aerogel, the specific surface area and mechanical strength of the material are improved, the titanium MOF is loaded on the surface of the aerogel to improve the photocatalytic activity, and the adsorption and catalysis and removal of waste gas are improved, and a layer of hydroxyapatite coating and hydrophobic treatment is deposited on the surface to make the material have corrosion resistance, hydrophobicity and better chemical stability; the material has high mechanical strength, high photocatalytic activity and strong corrosion resistance.

[0062] In Comparative Example 1, the specific surface area and mechanical strength decreased significantly, which may be due to the lack of silicon carbide nanowires, the loss of support of high-strength silicon carbide nanowires, the sudden drop in porosity of pure graphene oxide aerogel due to disordered stacking of layers, and the lack of stress sharing of silicon carbide nanowires, which caused the material to collapse in subsequent processing, resulting in a significant decrease in specific surface area and mechanical properties.

[0063] In Comparative Example 2, the adsorption and catalytic removal rate decreased significantly, which may be due to the lack of titanium acetylacetonate, which is the key to generating titanium MOF with photocatalytic activity. Titanium MOF is the core active component of the photocatalytic process, and its Ti-O cluster can effectively absorb light energy to generate photoelectrons and holes to drive redox reactions to degrade pollutants. The lack of titanium MOF material loses the photocatalytic active site, and the pollutants are only partially removed by physical adsorption or weak other activity, resulting in a significant decrease in photocatalytic degradation.

[0064] The salt fog resistance time in Comparative Example 3 is significantly shortened, which is probably due to the absence of Step 3. Step 3 is essentially to deposit a layer of hydroxyapatite coating on the surface of the organic-inorganic composite aerogel. Hydroxyapatite is an extremely stable, dense and corrosion-resistant inorganic mineral. The coating uniformly covers the surface of the aerogel skeleton, forming a physical barrier that effectively isolates the corrosive medium from the internal sensitive material, preventing and delaying the occurrence of corrosion reactions.

[0065] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, which can be understood by those of ordinary skill in the art.

Claims

1. A method for preparing an organic-inorganic composite photocatalytic porous material, characterized in that: The steps include: Step 1: Amination treatment is performed on silicon carbide nanowires to obtain an amination silicon carbide nanowire dispersion; the dispersion is compounded with a graphene oxide dispersion to obtain a graphene oxide / silicon carbide aerogel under surfactant and acidic conditions; Step 2: Prepare an iron complex solution, synthesize a titanium-based MOF precursor by a solvothermal method, add the iron complex, load the graphene oxide / silicon carbide aerogel, and obtain an organic-inorganic composite aerogel by vacuum impregnation and freeze drying; Step 3: Calcium nitrate solution, trisodium citrate and potassium dihydrogen phosphate solution are mixed and stirred in a reactor in sequence, the pH value is adjusted, and then the organic-inorganic composite aerogel is added, subjected to hydrothermal reaction, and centrifugal drying to obtain an organic-inorganic composite powder; the powder is surface-modified with 1H,1H,2H,2H-perfluorodecanethiol and triethylamine in an ethanol solvent, and washed and dried to obtain an organic-inorganic composite photocatalytic porous material.

2. The method for preparing an organic-inorganic composite photocatalytic porous material according to claim 1, characterized in that: In step 1, the specific preparation steps of graphene oxide / silicon carbide aerogel are as follows: Silicon carbide nanowires, ethanol and 3-aminopropyltriethoxysilane are added to a reactor and reacted at 80-90°C for 8-10 hours to obtain an amino-silicon carbide nanowire dispersion; 1wt% of graphene oxide dispersion and 1wt% of amino-silicon carbide nanowire dispersion are stirred at 60-80°C for 2-3 hours, sodium dodecylbenzenesulfonate and acetic acid are added, reacted at 120-150°C for 2-4 hours, and freeze-dried to obtain graphene oxide / silicon carbide aerogel.

3. The method for preparing an organic-inorganic composite photocatalytic porous material according to claim 2, characterized in that: The amount ratio of the silicon carbide nanowires, ethanol and 3-aminopropyltriethoxysilane is 3-5g:600-1000mL:30-50mL; The usage ratio of the graphene oxide dispersion, the amino-silicon carbide nanowire dispersion, sodium dodecylbenzenesulfonate and acetic acid is 600-1000 mL: 600-1000 mL: 0.6-0.8 g: 0.18-0.22 g.

4. The method for preparing an organic-inorganic composite photocatalytic porous material according to claim 1, characterized in that: In step 2, the specific preparation steps of the organic-inorganic composite aerogel are as follows: Add ethylene glycol, ferric acetylacetonate and disodium ethylenediaminetetraacetate into a reaction kettle and stir at 60-80°C for 30-40 minutes to obtain an iron complex solution; Titanium acetylacetonate and N,N-dimethylformamide are added to a reactor, ultrasonicated for 20-30 minutes, terephthalic acid is added, stirred for 2-3 hours, reacted at 120-130°C for 6-8 hours, and then an iron complex solution is added, reacted at 120-140°C for 12-14 hours, and then graphene oxide / silicon carbide aerogel is added. The mixture is vacuum soaked for 20-24 hours and freeze-dried for 10-12 hours to obtain an organic-inorganic composite aerogel.

5. The method for preparing an organic-inorganic composite photocatalytic porous material according to claim 4, characterized in that: The usage ratio of ethylene glycol, ferric acetylacetonate and disodium edetate is 20-30 mL: 0.6-0.8 g: 0.5-0.7 g; The usage ratio of the titanium acetylacetonate, N,N-dimethylformamide, terephthalic acid, iron complex solution and graphene oxide / silicon carbide aerogel is 0.85-0.95 mL: 80-90 mL: 150-170 mg: 20-30 mL: 3-5 g.

6. The method for preparing an organic-inorganic composite photocatalytic porous material according to claim 1, characterized in that: In step 3, the specific steps for preparing the organic-inorganic composite powder are as follows: 1.5 wt% calcium nitrate solution and trisodium citrate were added to a reaction kettle and stirred for 30-40 minutes. 1.2 wt% potassium dihydrogen phosphate solution was slowly added and stirred for 30-40 minutes. The pH value was adjusted to 7.8-8 with ammonia water. Then, the organic-inorganic composite aerogel was added and stirred at 80-90° C. for 2-3 hours. The mixture was filtered, the filter cake was centrifuged, and dried to obtain an organic-inorganic composite powder.

7. The method for preparing an organic-inorganic composite photocatalytic porous material according to claim 6, characterized in that: The usage ratio of the calcium nitrate solution, trisodium citrate, potassium dihydrogen phosphate solution and organic-inorganic composite aerogel is 100-120 mL: 3-5 g: 100-120 mL: 2-4 g.

8. The method for preparing an organic-inorganic composite photocatalytic porous material according to claim 1, characterized in that: In step 3, the specific preparation steps of the organic-inorganic composite photocatalytic porous material are as follows: Ethanol, organic-inorganic composite powder, 1H,1H,2H,2H-perfluorodecanethiol and triethylamine are added to a reaction kettle, ultrasonicated at 50-70° C. for 2-3 hours, filtered, the filter cake is washed with ethanol 3-5 times, and dried at 80-90° C. for 3-4 hours to obtain an organic-inorganic composite photocatalytic porous material.

9. The method for preparing an organic-inorganic composite photocatalytic porous material according to claim 8, characterized in that: The usage ratio of the ethanol, the organic-inorganic composite powder, 1H,1H,2H,2H-perfluorodecanethiol and triethylamine is 1200-1400 mL: 2-4 g: 2-4 g: 0.8-1 g.

10. An organic-inorganic composite photocatalytic porous material, characterized in that: Prepared by the preparation method according to any one of claims 1 to 9.

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