Preparation process of graphene-enhanced porous composite filter material of fume hood for waste gas purification

Abstract

The invention discloses a preparation process of a graphene-enhanced porous composite filter material of a fume hood for waste gas purification, belongs to the technical field of waste gas purification, and aims to solve the technical problem that the wet working condition adsorption capacity of the porous composite filter material of the fume hood in the prior art needs to be further improved. The preparation method specifically comprises the following steps: putting melamine sponge, phenyl trichlorosilane and normal hexane into a reaction kettle, reacting at room temperature for 14-16 hours, and performing post-treatment to obtain the phenyl modified melamine sponge. Fly ash is used as a base material, GO is loaded and reduced into rGO in situ, graphene is uniformly anchored, an aromatic structure is exposed, reaction nodes are introduced through phenyl silanization, finally, under the catalysis of FeCl, the graphene, octaphenyl POSS and phenyl melamine sponge are subjected to synergistic super-crosslinking, a three-dimensional hydrophobic porous network is formed, and the graphene / polyhedral oligomeric silsesquioxane / polyhedral oligomeric silsesquioxane / polyhedral oligomeric silsesquioxane / polyhedral oligomeric silsesquioxane composite material is obtained. The composite filter material with high specific surface area, good air permeability and wet working condition adsorption capacity is obtained.

Description

Technical Field

[0001] This invention relates to the field of waste gas purification technology, specifically to the preparation process of graphene-reinforced porous composite filter media for fume hoods used in waste gas purification. Background Technology

[0002] As an important piece of equipment for controlling the emission of organic waste gas in laboratories and industrial sites, the adsorption performance of the core component, the filter media, directly affects the waste gas purification efficiency and operational safety. Traditional fume hood filter media have gradually evolved from early single activated carbon materials to porous inorganic materials, organic porous materials, and their composite systems. By increasing the specific surface area, controlling the pore size structure, and enhancing the interaction with organic molecules, the efficient removal of volatile organic compounds can be achieved. However, under complex operating conditions, especially in the presence of water vapor and multi-component organic waste gas, problems such as rapid decay of the filter media's adsorption capacity, insufficient structural stability, and fluctuations in ventilation performance remain prominent, limiting their long-term stable application.

[0003] Currently, porous composite filter media for fume hoods often use activated carbon, molecular sieves, porous silicon materials, polymer porous materials and their composite systems as the main materials. Adsorption performance is improved through acid and alkali treatment, surface oxidation, metal ion loading, hydrophobic coating or physical composite conductive carbon materials. These modification methods can improve the initial adsorption capacity or selectivity to a certain extent, but they generally have problems such as weak bonding between the modified layer and the matrix, easy pore blockage, agglomeration failure of the introduced components, and the occupation of adsorption sites by water molecules in high humidity environments. At the same time, most inorganic fillers exist only in the form of physical filling, which makes it difficult to form a stable structural support in the porous network, resulting in increased air resistance and significant performance fluctuations of the filter media under long-term ventilation or humid and hot conditions.

[0004] In existing technologies, due to the complex chemical environment of the substrate surface, impurities and alkaline sites can easily interfere with organic reactions or adsorption processes, limiting the effective construction of porous structures. Furthermore, the accessibility and stability of aromatic or carbon-based components that enhance adsorption performance in the pore walls are insufficient, making it difficult to fully utilize π-π interactions. At the same time, the porous structure lacks a stable pore structure and hydrophobic regulation, resulting in the pore volume being occupied and the structure easily collapsing under wet conditions. It is difficult to solve the problem of balancing adsorption capacity, ventilation stability, and adaptability to wet conditions. Therefore, a solution is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a preparation process for graphene-reinforced porous composite filter media for exhaust gas purification fume hoods, which solves the technical problem that the wet adsorption capacity of porous composite filter media for fume hoods in the prior art needs to be further improved.

[0006] The objective of this invention can be achieved through the following technical solution: A process for preparing graphene-reinforced porous composite filter media for fume hoods used in waste gas purification includes the following steps:

[0007] S1. Melamine sponge, phenyltrichlorosilane and n-hexane are placed in a reaction vessel and reacted at room temperature for 14-16 h. After post-treatment, phenyl-modified melamine sponge is obtained.

[0008] S2. Place phenylsilanized composite graphene and chlorobenzene in a reaction vessel under nitrogen atmosphere and stir. Add phenyl-modified melamine sponge, octaphenyl-POSS and 2,3,5,6-tetrafluoro-p-dibromobenzyl. Stir at room temperature for 15-20 min. Add ferric chloride. Heat the reaction vessel to 40-50℃ and keep it at that temperature for 20-24 h. Post-process to obtain porous composite filter material.

[0009] Further, in step S1, the ratio of melamine sponge, phenyltrichlorosilane, and n-hexane is 4-6g:2-4mL:100-120mL, and the size of the melamine sponge is a cube with a side length of 1-3mm. The post-processing steps include: after the reaction is completed, filtration is performed, the filter cake is washed with ethanol 2-4 times, transferred to an oven at a temperature of 50-60℃, and dried to constant weight to obtain phenyl-modified melamine sponge.

[0010] Further, in step S2, the ratio of the amounts of phenylsilanized composite graphene, chlorobenzene, phenyl-modified melamine sponge, octaphenyl-POSS, 2,3,5,6-tetrafluoro-p-dibromobenzyl and ferric chloride is 0.6-0.8g:90-110mL:5.5-6.5g:1.2-1.6g:1.2-1.6g:6-8g. The post-processing steps include: after the reaction is completed, filtration is performed, the filter cake is washed with methanol 2-4 times, transferred to an oven at 70-80℃, and dried to constant weight to obtain porous composite filter material.

[0011] Furthermore, the preparation method of the phenylsilanized composite graphene is as follows: the modified fly ash graphene composite material, deionized water and ethanol are placed in a reaction vessel and stirred, phenyltrimethoxysilane is added, acetic acid solution is added to adjust the pH to 4-5, the reaction vessel is heated to 40-50℃, and the reaction is kept at this temperature for 2-4 hours. The phenylsilanized composite graphene is then obtained through post-treatment.

[0012] Furthermore, the ratio of the modified fly ash graphene composite material, deionized water, ethanol, and phenyltrimethoxysilane is 8-10g:10-15mL:60-80mL:1-2g, and the concentration of the acetic acid solution is 3-5wt%. The post-treatment steps include: after the reaction is completed, the mixture is filtered, the filter cake is washed 2-4 times with deionized water and ethanol, transferred to an oven at 50-60℃, and dried to constant weight to obtain phenylsilanized composite graphene.

[0013] Furthermore, the modified fly ash graphene composite material is prepared by the following steps:

[0014] A1. Place graphene oxide and deionized water in a reaction vessel and stir. Add ammonia water to adjust the pH to 9-10. Add pretreated fly ash and stir at room temperature for 2-4 hours. Post-treatment yields fly ash-loaded GO composite.

[0015] A2. Place fly ash-loaded GO composite and deionized water in a reactor and stir. Add ascorbic acid and heat the reactor to 80-90℃. Keep the reaction at this temperature for 3-4 hours. After post-treatment, fly ash-loaded rGO composite is obtained.

[0016] A3. Place the fly ash-loaded rGO composite in a tube furnace under nitrogen atmosphere protection, heat it to 300-350℃ at a rate of 5-10℃ / min, hold it at that temperature for 1-2 hours, cool it, and grind it through a 300-mesh sieve to obtain the modified fly ash rGO composite material.

[0017] Further, in step A1, the ratio of graphene oxide, deionized water, and pretreated fly ash is 0.1-0.2g:20-30mL:0.5-1g, and the concentration of ammonia is 25-30wt%. The post-treatment step includes: after the reaction is completed, the mixture is filtered, the filter cake is washed 2-4 times with deionized water and ethanol, transferred to an oven at 80-100℃, and dried to constant weight to obtain fly ash-supported GO composite.

[0018] Further, in step A2, the ratio of the fly ash-loaded GO complex, deionized water, and ascorbic acid is 8-10g:18-25mL:0.5-1g. The post-processing steps include: after the reaction is completed, the mixture is filtered, the filter cake is washed with deionized water 2-4 times, transferred to an oven at 80-100℃, and dried to constant weight to obtain the fly ash-loaded rGO complex.

[0019] Furthermore, the pretreated fly ash is prepared by the following steps:

[0020] B1. Place fly ash and hydrochloric acid aqueous solution in a reaction vessel and stir at room temperature for 1-2 hours. Post-treatment yields alkali-free fly ash.

[0021] B2. Add the de-alkali fly ash into a tubular furnace and heat it to 500-550℃ at a heating rate of 5-10℃ / min. Hold the temperature for 1-2 hours. After cooling, grind it through a 200-mesh sieve to obtain pretreated fly ash.

[0022] Further, in step B1, the ratio of fly ash to hydrochloric acid aqueous solution is 1g:10mL, and the concentration of hydrochloric acid aqueous solution is 0.5-1.0mol / L. The post-treatment step includes: after the reaction is completed, the mixture is filtered, the filter cake is washed with deionized water and ethanol until neutral, transferred to an oven at a temperature of 50-60℃, and dried to constant weight to obtain alkali-free fly ash.

[0023] The present invention has the following beneficial effects:

[0024] 1. This invention constructs a high-purity inorganic substrate structure suitable for Friedel-Crafts type crosslinking reactions by de-alkali treatment and high-temperature activation of fly ash. Hydrochloric acid de-alkali treatment removes free alkali and alkali metal oxides from the fly ash, preventing these alkaline impurities from neutralizing the ferric chloride Lewis acid catalyst in subsequent reactions. This ensures that the aromatic electrophilic substitution reaction proceeds fully and uniformly, allowing the hypercrosslinked network to continuously form on the substrate surface. This effectively avoids pore structure collapse caused by insufficient local crosslinking. Further high-temperature heat treatment removes residual organic carbon and unstable minerals. The decomposition of the phase and water of crystallization reduces physical blockage of the organic crosslinking system. At the same time, it induces the formation of microcracks and defect sites in the glassy framework of SiO2 and Al2O3, significantly improving the specific surface area and hydroxyl density of the porous composite filter material. This structural feature makes the crosslinking reaction easier to carry out in three-dimensional space, which is conducive to the formation of a porous structure with uniform pore size distribution and good connectivity. This makes the overall airflow distribution of the filter material more uniform, effectively reducing the dispersion of air permeability at different locations and exhibiting a low coefficient of variation of air permeability. This is beneficial for the fume hood to maintain stable and controllable ventilation performance during long-term operation.

[0025] 2. This invention also uses de-alkali activated fly ash as a carrier to load GO and further reduce it to rGO, constructing a composite substrate with both structural stability and high adsorption activity. The alkaline sites and impurities on the surface of the fly ash after de-alkali and high-temperature treatment are significantly reduced, avoiding side reactions or adsorption deactivation of benzyl halides or FeCl3 during the Friedel-Crafts reaction. This ensures that the aromatic structure on the rGO surface can participate in cross-linking and be exposed inside the porous network. GO is uniformly anchored to the fly ash surface through electrostatic and hydrogen bonding interactions, forming a π-electron-rich rGO layer after reduction. Thermal stabilization treatment inhibits the aggregation of the sheets, allowing the aromatic structure to reach a high degree on the pore walls. This structure not only improves the effective utilization rate of graphene in the filter material, but also enhances its π–π interaction and hydrophobic adsorption capacity for organic waste gas molecules. This allows the composite filter material to significantly improve the waste gas removal efficiency while maintaining high porosity and delaying adsorption saturation, thereby extending the service life of the fume hood filter material.

[0026] 3. This invention also modifies the modified fly ash graphene composite material by phenylsilanization. The aromatic structure introduced on the surface of the phenylsilanized substrate can participate in the Friedel-Crafts type crosslinking reaction, transforming the inorganic particles, which were originally mainly physically filled, into reaction nodes in the super-crosslinked network. Under the synergistic effect of multiple aromatic components, the particles are covalently embedded in the three-dimensional super-crosslinked network, which structurally inhibits particle migration and pore wall collapse, while reducing the pore surface energy. This significantly improves the structural stability and hydrophobic and moisture-resistant properties of the composite filter material. The hydrophobic and moisture-resistant properties are achieved by inhibiting the preferential adsorption of water molecules on the pore walls and the formation of water films, preventing the effective pore volume and active sites from being occupied by water vapor. This maintains the openness of the porous structure to organic waste gas molecules and the stability of the mass transfer channels, so that the porous composite filter material can maintain a high and stable adsorption capacity under fluctuating humidity conditions. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The melamine sponge used in this invention is sourced from Versota® melamine sponge, and its operating temperature is -240℃ to 220℃.

[0029] The octaphenyl-POSS used in this invention was purchased from Hubei Xingyan New Material Technology Co., Ltd., with a molecular weight of 1033.508 and CAS number 5256-79-1.

[0030] The graphene oxide used in this invention was purchased from Beijing Meiston Technology Development Co., Ltd., with a sheet lateral dimension of 0.5-5μm and model number SY-GO-S.

[0031] The fly ash used in this invention was purchased from Lingshou County Bohan Mineral Products Co., Ltd., with a particle size of 10-25 μm and a density of 1.9 g / cm³. 3 .

[0032] Example 1

[0033] This embodiment provides a process for preparing pretreated fly ash, specifically including the following steps:

[0034] Step I: Preparation of Alkali-Removed Fly Ash

[0035] Weigh 10g of fly ash and 100mL of 0.5mol / L hydrochloric acid aqueous solution and place them in a reaction vessel. Stir at room temperature for 1h. After the reaction is complete, filter the mixture. Wash the filter cake with deionized water and ethanol until neutral. Transfer it to an oven at 50℃ and dry it to constant weight to obtain alkali-free fly ash.

[0036] Step II: Preparation of pretreated fly ash

[0037] The de-alkali fly ash was added to a tubular furnace and heated to 500°C at a heating rate of 5°C / min. The temperature was maintained for 1 hour. After cooling, the fly ash was ground through a 200-mesh sieve to obtain pretreated fly ash.

[0038] Hydrochloric acid neutralizes and dissolves free alkali and soluble alkali metal oxides in fly ash, converting them into soluble chlorides and removing them. This reduces the ash alkalinity of fly ash, dissolves impurities, and opens some of the pore structure. Furthermore, heat treatment decomposes residual organic carbon, water of crystallization, and unstable mineral phases, while promoting the activation of the glassy SiO2-Al2O3 framework and the formation of microcracks. This increases the specific surface area and reactivity of fly ash, providing more active sites and diffusion channels for subsequent chemical modification.

[0039] Example 2

[0040] This embodiment provides a process for preparing pretreated fly ash, specifically including the following steps:

[0041] Step I: Preparation of Alkali-Removed Fly Ash

[0042] Weigh 10g of fly ash and 100mL of 0.75mol / L hydrochloric acid aqueous solution and place them in a reaction vessel. Stir at room temperature for 1.5h. After the reaction is complete, filter the mixture. Wash the filter cake with deionized water and ethanol until neutral. Transfer it to an oven at 55℃ and dry it to constant weight to obtain alkali-free fly ash.

[0043] Step II: Preparation of pretreated fly ash

[0044] The de-alkali fly ash was added to a tubular furnace and heated to 525°C at a heating rate of 7°C / min. The temperature was maintained for 1.5 hours. After cooling, the fly ash was ground through a 200-mesh sieve to obtain pretreated fly ash.

[0045] Example 3

[0046] This embodiment provides a process for preparing pretreated fly ash, specifically including the following steps:

[0047] Step I: Preparation of Alkali-Removed Fly Ash

[0048] Weigh 10g of fly ash and 100mL of 1.0mol / L hydrochloric acid aqueous solution and place them in a reaction vessel. Stir at room temperature for 2h. After the reaction is complete, filter the mixture. Wash the filter cake with deionized water and ethanol until neutral. Transfer it to an oven at 60℃ and dry it to constant weight to obtain alkali-free fly ash.

[0049] Step II: Preparation of pretreated fly ash

[0050] The de-alkali fly ash was added to a tubular furnace and heated to 550°C at a heating rate of 10°C / min. The temperature was maintained for 2 hours. After cooling, the fly ash was ground through a 200-mesh sieve to obtain pretreated fly ash.

[0051] Example 4

[0052] This embodiment provides a preparation process for modified fly ash graphene composite material, specifically including the following steps:

[0053] Step 1: Preparation of fly ash-supported GO composite

[0054] Weigh 1g of graphene oxide and 200mL of deionized water and place them in a reaction vessel and stir. Add 25wt% ammonia water to adjust the pH to 9. Add 5g of pretreated fly ash prepared in Example 1 and stir at room temperature for 2h. After the reaction is complete, filter the mixture. Wash the filter cake twice with deionized water and ethanol. Transfer it to an oven at 80℃ and dry it to constant weight to obtain fly ash-supported GO composite.

[0055] Step 2: Preparation of fly ash-supported rGO composite

[0056] Weigh 80g of fly ash-supported GO composite and 180mL of deionized water and place them in a reaction vessel and stir. Add 5g of ascorbic acid, heat the reaction vessel to 80℃, and keep it at that temperature for 3h. After the reaction is complete, filter the mixture, wash the filter cake twice with deionized water, transfer it to an oven at 80℃, and dry it to constant weight to obtain fly ash-supported rGO composite.

[0057] Step (3): Preparation of modified fly ash rGO composite material

[0058] The fly ash-loaded rGO composite was placed in a tube furnace under nitrogen atmosphere protection, heated to 300℃ at a rate of 5℃ / min, held for 1 hour, cooled, and then ground through a 300-mesh sieve to obtain the modified fly ash rGO composite material.

[0059] Under alkaline conditions, the oxygen-containing functional groups such as carboxyl groups on the surface of GO (graphene oxide) are deprotonated and become strongly negatively charged. These groups can bind to the active hydroxyl groups exposed on the surface of pretreated fly ash through electrostatic interactions and hydrogen bonding, promoting the uniform adsorption and loading of GO onto the surface of pretreated fly ash particles, forming a stable fly ash-loaded GO complex. Furthermore, ascorbic acid, as a green reducing agent, partially removes the epoxy, hydroxyl, and carboxyl groups from GO and restores sp. 2 The conjugated structure generates rGO (reduced graphene oxide) with stronger conductivity, while the rGO remains firmly anchored to the surface of the pretreated fly ash. Through high-temperature treatment, unstable components in the composite can be removed, and the agglomeration of rGO sheets can be prevented, resulting in modified fly ash rGO composite material.

[0060] Example 5

[0061] This embodiment provides a preparation process for modified fly ash graphene composite material, specifically including the following steps:

[0062] Step 1: Preparation of fly ash-supported GO composite

[0063] Weigh 1.5g of graphene oxide and 250mL of deionized water and place them in a reaction vessel and stir. Add 27.5wt% ammonia water to adjust the pH to 9.5. Add 7.5g of pretreated fly ash prepared in Example 2 and stir at room temperature for 3h. After the reaction is complete, filter the mixture and wash the filter cake three times with deionized water and ethanol. Transfer the cake to an oven at 90℃ and dry it to constant weight to obtain fly ash-supported GO composite.

[0064] Step 2: Preparation of fly ash-supported rGO composite

[0065] Weigh 90g of fly ash-supported GO composite and 210mL of deionized water and place them in a reaction vessel and stir. Add 7.5g of ascorbic acid, heat the reaction vessel to 85℃, and keep it at that temperature for 3.5h. After the reaction is complete, filter the mixture, wash the filter cake three times with deionized water, transfer it to an oven at 90℃, and dry it to constant weight to obtain fly ash-supported rGO composite.

[0066] Step (3): Preparation of modified fly ash rGO composite material

[0067] The fly ash-loaded rGO composite was placed in a tube furnace under nitrogen atmosphere protection, heated to 325℃ at a rate of 7℃ / min, held for 1.5h, cooled, and then ground through a 300-mesh sieve to obtain the modified fly ash rGO composite material.

[0068] Example 6

[0069] This embodiment provides a preparation process for modified fly ash graphene composite material, specifically including the following steps:

[0070] Step 1: Preparation of fly ash-supported GO composite

[0071] Weigh 2g of graphene oxide and 300mL of deionized water and place them in a reaction vessel and stir. Add 30wt% ammonia water to adjust the pH to 10. Add 10g of pretreated fly ash prepared in Example 3 and stir at room temperature for 4h. After the reaction is complete, filter the mixture and wash the filter cake 4 times with deionized water and ethanol. Transfer the cake to an oven at 100℃ and dry it to constant weight to obtain fly ash-supported GO composite.

[0072] Step 2: Preparation of fly ash-supported rGO composite

[0073] Weigh 100g of fly ash-supported GO composite and 250mL of deionized water and place them in a reaction vessel and stir. Add 10g of ascorbic acid, heat the reaction vessel to 90℃, and keep it at that temperature for 4h. After the reaction is complete, filter the mixture, wash the filter cake 4 times with deionized water, transfer it to an oven at 100℃, and dry it to constant weight to obtain fly ash-supported rGO composite.

[0074] Step (3): Preparation of modified fly ash rGO composite material

[0075] The fly ash-loaded rGO composite was placed in a tube furnace under nitrogen atmosphere protection, heated to 350℃ at a rate of 10℃ / min, held for 2 hours, cooled, and then ground through a 300-mesh sieve to obtain the modified fly ash rGO composite material.

[0076] Example 7

[0077] This embodiment provides a process for preparing a graphene-reinforced porous composite filter material for fume hoods used in exhaust gas purification, specifically including the following steps:

[0078] Step ①: Preparation of phenylsilanized composite graphene

[0079] Weigh 80g of the modified fly ash graphene composite material prepared in Example 4, 100mL of deionized water and 600mL of ethanol and place them in a reaction vessel and stir. Add 10g of phenyltrimethoxysilane and adjust the pH to 4 with 3wt% acetic acid solution. Heat the reaction vessel to 40℃ and keep it at that temperature for 2h. After the reaction is complete, filter the mixture and wash the filter cake twice with deionized water and ethanol. Transfer the cake to an oven at 50℃ and dry it to constant weight to obtain phenylsilanized composite graphene.

[0080] Step ②: Preparation of phenyl-modified melamine sponge

[0081] Weigh out 40g of cubic melamine sponge with a side length of 1mm, 20mL of phenyltrichlorosilane and 1000mL of n-hexane and place them in a reaction vessel. React at room temperature for 14h. After the reaction is complete, filter the mixture and wash the filter cake twice with ethanol. Transfer the cake to an oven at 50℃ and dry it to constant weight to obtain phenyl-modified melamine sponge.

[0082] Step 3: Preparation of porous composite filter media

[0083] Weigh 6g of phenylsilanized composite graphene and 900mL of chlorobenzene and place them in a reaction vessel under nitrogen atmosphere and stir. Add 55g of phenyl-modified melamine sponge, 12g of octaphenyl-POSS and 12g of 2,3,5,6-tetrafluoro-p-dibromobenzyl, stir at room temperature for 15min, add 60g of ferric chloride, heat the reaction vessel to 40℃ and keep it at that temperature for 20h. After the reaction is complete, filter, wash the filter cake twice with methanol, transfer it to an oven at 70℃ and dry it to constant weight to obtain porous composite filter material.

[0084] Phenylacetyltrimethoxysilane hydrolyzes under weakly acidic conditions to generate silanol, which then undergoes a condensation reaction with hydroxyl groups on the surface of the modified fly ash rGO composite material. This introduces phenyl groups onto the surface of the composite material, enhancing its hydrophobicity and compatibility with the organic phase. Furthermore, phenyltrichlorosilane undergoes a silanization reaction with the -NH- group on the melamine sponge skeleton, covering the sponge surface with phenyl groups. This significantly improves the hydrophobicity and aromatic structure affinity of the melamine sponge. Under the Lewis acid catalysis of ferric chloride, the aromatic groups in the system (phenylsilanized composite graphene, phenyl-modified sponge, and octaphenyl-POSS) undergo Friedel-Crafts-type crosslinking and physicochemical complexation with 2,3,5,6-tetrafluoro-p-dibromobenzyl, constructing a stable porous network structure with sponge as a three-dimensional support, graphene as a functional filler, and POSS as a rigid node. This results in a porous composite filter material that combines high porosity, hydrophobicity, and structural stability.

[0085] Example 8

[0086] This embodiment provides a process for preparing a graphene-reinforced porous composite filter material for fume hoods used in exhaust gas purification, specifically including the following steps:

[0087] Step ①: Preparation of phenylsilanized composite graphene

[0088] Weigh 90g of the modified fly ash graphene composite material prepared in Example 5, 125mL of deionized water and 700mL of ethanol and place them in a reaction vessel and stir. Add 15g of phenyltrimethoxysilane and adjust the pH to 4.5 with 4wt% acetic acid solution. Heat the reaction vessel to 45℃ and keep it at that temperature for 3h. After the reaction is complete, filter the mixture and wash the filter cake three times with deionized water and ethanol. Transfer the cake to an oven at 55℃ and dry it to constant weight to obtain phenylsilanized composite graphene.

[0089] Step ②: Preparation of phenyl-modified melamine sponge

[0090] Weigh out 50g of cubic melamine sponge with a side length of 2mm, 30mL of phenyltrichlorosilane and 1100mL of n-hexane and place them in a reaction vessel. React at room temperature for 15h. After the reaction is complete, filter the mixture and wash the filter cake three times with ethanol. Transfer the cake to an oven at 55℃ and dry it to constant weight to obtain phenyl-modified melamine sponge.

[0091] Step 3: Preparation of porous composite filter media

[0092] Weigh 7g of phenylsilanized composite graphene and 1000mL of chlorobenzene and place them in a reaction vessel under nitrogen atmosphere and stir. Add 60g of phenyl-modified melamine sponge, 14g of octaphenyl-POSS and 14g of 2,3,5,6-tetrafluoro-p-dibromobenzyl, stir at room temperature for 17min, add 70g of ferric chloride, heat the reaction vessel to 45℃ and keep it at that temperature for 22h. After the reaction is complete, filter, wash the filter cake three times with methanol, transfer it to an oven at 75℃ and dry it to constant weight to obtain porous composite filter material.

[0093] Example 9

[0094] This embodiment provides a process for preparing a graphene-reinforced porous composite filter material for fume hoods used in exhaust gas purification, specifically including the following steps:

[0095] Step ①: Preparation of phenylsilanized composite graphene

[0096] Weigh 100g of the modified fly ash graphene composite material prepared in Example 6, 150mL of deionized water and 800mL of ethanol and place them in a reaction vessel and stir. Add 20g of phenyltrimethoxysilane and adjust the pH to 5 with 5wt% acetic acid solution. Heat the reaction vessel to 50℃ and keep it at that temperature for 4h. After the reaction is complete, filter the mixture and wash the filter cake 4 times with deionized water and ethanol. Transfer the cake to an oven at 60℃ and dry it to constant weight to obtain phenylsilanized composite graphene.

[0097] Step ②: Preparation of phenyl-modified melamine sponge

[0098] Weigh out 60g of cubic melamine sponge with a side length of 3mm, 40mL of phenyltrichlorosilane and 1200mL of n-hexane and place them in a reaction vessel. React at room temperature for 16h. After the reaction is complete, filter the mixture and wash the filter cake 4 times with ethanol. Transfer the cake to an oven at 60℃ and dry it to constant weight to obtain phenyl-modified melamine sponge.

[0099] Step 3: Preparation of porous composite filter media

[0100] Weigh 8g of phenylsilanized composite graphene and 1100mL of chlorobenzene and place them in a reaction vessel under nitrogen atmosphere and stir. Add 65g of phenyl-modified melamine sponge, 16g of octaphenyl-POSS and 16g of 2,3,5,6-tetrafluoro-p-dibromobenzyl, stir at room temperature for 20min, add 80g of ferric chloride, heat the reaction vessel to 50℃ and keep it at that temperature for 24h. After the reaction is complete, filter, wash the filter cake 4 times with methanol, transfer it to an oven at 80℃ and dry it to constant weight to obtain porous composite filter material.

[0101] Comparative Example 1

[0102] The difference between this comparative example and Example 9 is that, in step (1) when preparing the fly ash-supported GO composite, an equal amount of fly ash was used to replace the pretreated fly ash.

[0103] Comparative Example 2

[0104] The difference between this comparative example and Example 9 is that, in step ①, when preparing phenylsilanized composite graphene, an equal amount of pretreated fly ash was used to replace the modified fly ash graphene composite material.

[0105] Comparative Example 3

[0106] The difference between this comparative example and Example 9 is that, in step ③, when preparing the porous composite filter material, the addition of 2,3,5,6-tetrafluoro-p-dibromobenzyl was omitted.

[0107] Performance testing:

[0108] The adsorption performance of the porous composite filter media prepared in Examples 7-9 and Comparative Examples 1-3 was tested using fixed-bed adsorption experiments. A four-component mixed gas and a five-component mixed gas containing water vapor (wherein the four-component mixed gas consisted of toluene, xylene, acetone, and n-hexane in a volume ratio of 1:1:1:1, and the five-component mixed gas containing water vapor consisted of water vapor, toluene, xylene, acetone, and n-hexane in a volume ratio of 1:1:1:1:1) were used as adsorbates. The mixed gases were passed through a fixed bed containing porous composite filter media, and the concentration change through the bed was monitored. The fixed bed temperature was 25°C, the gas flow rate was 100 mL / min, and the filter media loading was 10 g. The test was stopped when the outlet concentration stabilized at 5% of the inlet concentration. The adsorption capacity was determined as the weight of the adsorbed mixed gas (mg) / the weight of the adsorbent (g), in mg·g⁻¹. -1 ;

[0109] The pore capacity and specific surface area of ​​the porous composite filter media prepared in Examples 7-9 and Comparative Examples 1-3 were determined in accordance with the standard GB / T 19587-2017 "Determination of Specific Surface Area of ​​Solid Substances by Gas Adsorption BET Method".

[0110] The air permeability variation coefficients of the porous composite filter media prepared in Examples 7-9 and Comparative Examples 1-3 were determined according to the standard FZ / T 64102-2023 "Hard Filter Media for High Temperature Filter Cartridges". The specific data are shown in Table 1.

[0111] Table 1 - Performance Test Data of Samples

[0112]

[0113] Comparative analysis of the data in Table 1 above shows that the porous composite filter material prepared in this invention has an adsorption capacity of 455 mg·g for a four-component mixed gas. -1 The adsorption capacity for a five-component gas mixture containing water vapor is 412 mg·g. -1 The pore size is 0.52 cm³. 3 ·g -1 Specific surface area is 703 m² 2 ·g -1Meanwhile, the coefficient of variation of air permeability is 3.5%, and all data are better than the comparative example. This indicates that the composite material of fly ash and graphene in this invention is used as the substrate. After dealkalization and impurity removal with hydrochloric acid and high-temperature activation, a high-purity multi-defect surface that can participate in the Friedel-Crafts crosslinking reaction is constructed. The treated fly ash is loaded with GO and reduced in situ to generate rGO, so that the graphene is uniformly anchored, the sheets do not agglomerate, and the aromatic structure is exposed on the pore wall. Then, phenyl silanization modification is used to introduce aromatic groups, so that the inorganic particles are transformed from passive filling to reactive nodes. Finally, aromatic supercrosslinking is carried out in synergy with octaphenyl POSS and phenyl melamine sponge under FeCl3 catalysis to form a covalently embedded three-dimensional hydrophobic porous network, and a porous composite filter material with high specific surface area, air permeability and wet working condition adsorption capacity is obtained.

[0114] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A process for the preparation of graphene reinforced porous composite filter material for fume exhaust hood, characterized in that, The method comprises the following steps: S1, melamine sponge, phenyltrichlorosilane and n-hexane are placed in a reaction kettle, and the reaction is carried out at room temperature for 14-16 h, and then the phenyl-modified melamine sponge is obtained by post-treatment; S2, the phenyl-silane composite graphene and chlorobenzene are placed in a reaction kettle protected by nitrogen atmosphere and stirred, the phenyl-modified melamine sponge, octaphenyl-POSS and 2,3,5,6-tetrafluoro-p-dibromobenzene are added, and the mixture is stirred at room temperature for 15-20 min, then ferric chloride is added, the reaction kettle is heated to 40-50 DEG C, and the reaction is carried out for 20-24 h, and then the porous composite filter material is obtained by post-treatment.

2. The process for the preparation of graphene reinforced vented cabinet porous composite filter for exhaust gas purification as claimed in claim 1 wherein, In step S1, the amount ratio of the melamine sponge, phenyltrichlorosilane and n-hexane is 4-6 g:2-4 mL:100-120 mL; in step S2, the amount ratio of the phenyl-silane composite graphene, chlorobenzene, phenyl-modified melamine sponge, octaphenyl-POSS, 2,3,5,6-tetrafluoro-p-dibromobenzene and ferric chloride is 0.6-0.8 g:90-110 mL:5.5-6.5 g:1.2-1.6 g:1.2-1.6 g:6-8 g.

3. The process for the preparation of graphene reinforced fume hood exhaust air purification porous composite filter material as claimed in claim 1 wherein, The preparation method of the phenyl-silane composite graphene is as follows: the modified fly ash graphene composite material, deionized water and ethanol are placed in a reaction kettle and stirred, phenyltrimethoxysilane is added, an acetic acid solution is added to adjust the pH to 4-5, the reaction kettle is heated to 40-50 DEG C, and the reaction is carried out for 2-4 h, and then the phenyl-silane composite graphene is obtained by post-treatment.

4. The process for the preparation of graphene reinforced vented cabinet porous composite filter for exhaust gas purification as claimed in claim 3 wherein, The amount ratio of the modified fly ash graphene composite material, deionized water, ethanol and phenyltrimethoxysilane is 8-10 g:10-15 mL:60-80 mL:1-2 g, and the concentration of the acetic acid solution is 3-5 wt%.

5. The process for the preparation of graphene reinforced vented cabinet porous composite filter for exhaust gas purification as claimed in claim 3 wherein, The modified fly ash graphene composite material is prepared by the following steps: A1, graphene oxide and deionized water are placed in a reaction kettle and stirred, ammonia water is added to adjust the pH to 9-10, and pretreated fly ash is added, and the mixture is stirred at room temperature for 2-4 h, and then the fly ash loaded GO composite is obtained by post-treatment; A2, the fly ash loaded GO composite and deionized water are placed in a reaction kettle and stirred, ascorbic acid is added, the reaction kettle is heated to 80-90 DEG C, and the reaction is carried out for 3-4 h, and then the fly ash loaded rGO composite is obtained by post-treatment; A3, the fly ash loaded rGO composite is placed in a tube furnace protected by nitrogen atmosphere, heated to 300-350 DEG C at a rate of 5-10 DEG C / min, and kept for 1-2 h, cooled, ground through a 200 mesh sieve, and then the modified fly ash rGO composite material is obtained.

6. The process for the preparation of graphene reinforced vented cabinet porous composite filter for exhaust gas purification as claimed in claim 5 wherein, In step A1, the amount ratio of the graphene oxide, deionized water and pretreated fly ash is 0.1-0.2 g:20-30 mL:0.5-1 g, and the concentration of the ammonia water is 25-30 wt%; in step A2, the amount ratio of the fly ash loaded GO composite, deionized water and ascorbic acid is 8-10 g:18-25 mL:0.5-1 g.

7. The process for the preparation of graphene reinforced vented cabinet porous composite filter for exhaust gas purification as claimed in claim 5 wherein, The pretreated fly ash is prepared by the following steps: B1, fly ash and hydrochloric acid aqueous solution are placed in a reaction kettle, stirred at room temperature for 1-2 h, and then the alkali-free fly ash is obtained by post-treatment; B2, the de-alkali fly ash is added into a tube furnace, and heated to 500-550℃ at a heating rate of 5-10℃ / min, and kept for 1-2h, and after cooling, grinded through a 300 mesh sieve to obtain the pretreated fly ash.

8. The process for the preparation of graphene reinforced vented cabinet porous composite filter for exhaust gas purification as claimed in claim 7 wherein, In step B1, the fly ash and the hydrochloric acid aqueous solution are used in a ratio of 1g:10mL, and the concentration of the hydrochloric acid aqueous solution is 0.5-1.0mol / L.

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