A filter material for removing acidic gas and preparation method thereof

Abstract

The present invention relates to the technical field of filter material preparation, and in particular to a filter material for removing acidic gases and a preparation method thereof, comprising the following steps: S1, soaking fiber filaments in urea-modified epoxy resin, ultrasonicating for 10 to 20 minutes, and taking them out to obtain pretreated fiber filaments; S2, laying the pretreated fiber filaments in step S1 flat, uniformly spraying modified nano-activated carbon with a thickness of 0.5 to 0.7 mm on the surface thereof, and curing at 60 to 80° C. for 4 to 8 hours to obtain the filter material for removing acidic gases. The filter material for removing acidic gases of the present invention has good fracture toughness and acid and alkali resistance, and increases the filter material's ability to adsorb acidic gases through the synergistic effect of physical adsorption and chemical adsorption. In addition, the electrostatic effect of the fiber filaments can also remove smoke and dust in the air, achieving the effect of purifying the air. At the same time, the filter material of the present invention can be recycled and reused multiple times, saving use costs, and there is no secondary pollution in post-processing.

Description

Technical Field

[0001] The present invention relates to the technical field of filter material preparation, and in particular to a filter material for removing acidic gas and a preparation method thereof. Background Art

[0002] Acidic gases such as SO2, HCl, H2S, and nitrogen oxides are the main components of acid rain, which corrodes buildings and facilities, causing severe economic losses. Furthermore, these acidic gases can affect human health, leading to respiratory illnesses such as asthma and chronic obstructive pulmonary disease. Therefore, strict control of these acidic gases and their elimination at their source are essential.

[0003] Currently, the primary method for treating acidic gases is physical adsorption, which primarily utilizes adsorptive materials such as activated carbon. However, this method has a limited adsorption capacity and is prone to saturation, leading to desorption and secondary pollution. Therefore, there is a need to develop adsorbent materials that can adsorb acidic gases with high and stable adsorption capacity. For example, CN111068511B discloses a "deacidifier for removing acidic gases from high-temperature flue gas and a method for preparing the same." The deacidifier is prepared from platinum-based salts, calcium-based salts, cerium-based salts, an inorganic base, and a carrier. While the deacidifier effectively adsorbs acidic gases and is not prone to agglomeration or sintering, it also contains a large amount of inorganic dust in the high-temperature flue gas, which also has an impact on the environment. This patent does not address or address the adsorption of inorganic dust.

[0004] For example, CN104437401A discloses "an activated carbon filter material with electrostatic adsorption and negative ion release, and its preparation method." This method removes dust and acidic gases from flue gas by modifying activated carbon and using tourmaline powder. The filter material has a long lifespan and is suitable for producing air conditioning filters. However, the filter material is a consumable item during actual use, resulting in high costs. Once adsorption reaches saturation, it needs to be replaced, and desorption may occur during post-processing, causing secondary pollution. Currently, there is little research on the recycling of acid-removing filter materials, but it is undoubtedly a hot research topic.

[0005] Therefore, it is urgent to develop a filter material that can remove smoke and acid, can be recycled, and is green and environmentally friendly. Summary of the Invention

[0006] To address the shortcomings of the prior art, the present invention provides a filter material for removing acidic gases and a method for preparing the same. The filter material has a simple preparation process, utilizes physical and chemical adsorption to synergistically remove acidic gases while also removing smoke and purifying the air. Furthermore, the material can be recycled over a long period of time, without secondary pollution during post-processing.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] In one aspect, the present invention provides a method for preparing a filter material for removing acidic gas, comprising the following steps:

[0009] S1, soaking the fiber in urea-modified epoxy resin, ultrasonicating for 10 to 20 minutes, and then taking it out to obtain pretreated fiber;

[0010] S2. Lay the pretreated fiber filaments in step S1 flat, spray the modified nano-activated carbon with a thickness of 0.5 to 0.7 mm evenly on the surface, cure at 60 to 80° C. for 4 to 8 hours, and then stack them into a filter material with a thickness greater than or equal to 7 cm to obtain a filter material for removing acidic gas.

[0011] In some embodiments, the fiber filaments are one or more of polyester fiber filaments, nylon fiber filaments, and polypropylene fiber filaments, and the fiber filaments have a diameter of 5 to 20 μm.

[0012] Preferably, the fiber filaments are polyester fiber filaments, and the fiber filament diameter is 13 μm.

[0013] The applicant selected fiber filaments with electrostatic effect and good acid and high temperature resistance, which can prevent the acid removal filter material from aging and breaking due to temperature increase and corrosion during use, and can improve the stability of the acid removal filter material. At the same time, its electrostatic effect can adsorb inorganic dust in the air; in addition, the applicant controls the specific surface area of ​​the fiber filaments by adjusting the diameter of the fiber filaments, so that the amount of modified nano-activated carbon loaded per unit area is greater, thereby improving the adsorption performance of the acid removal filter material.

[0014] In some embodiments, the ultrasound frequency is 20 to 50 kHz.

[0015] Preferably, the ultrasonic frequency is 35 kHz.

[0016] The urea-modified epoxy resin system is relatively viscous. The applicant can better disperse the fiber filaments in the urea-modified epoxy resin system by adjusting the ultrasonic frequency.

[0017] In some embodiments, the pretreated fiber filaments are laid flat to a thickness of 0.5 to 1.5 mm.

[0018] Preferably, the pretreated fiber filaments are laid flat with a thickness of 1 mm.

[0019] The modified nano-activated carbon in this application can be loaded on the surface of the fiber filaments by spraying, thereby increasing the contact area between the modified nano-activated carbon and the acidic gas. In addition, the applicant can make the modified nano-activated carbon sprayed more evenly by adjusting the thickness of the pre-treated fiber filaments, so that more modified nano-activated carbon is loaded on the unit area of ​​the fiber filaments, thereby better improving the adsorption performance of the acid removal filter material.

[0020] In some embodiments, the method for preparing the urea-modified epoxy resin comprises the following steps:

[0021] (1) dissolving the polyetheramine and the catalyst in a solvent, slowly adding the isocyanate compound at -5 to 5°C, heating to 20 to 30°C and reacting for 10 to 14 hours to obtain an isocyanate prepolymer;

[0022] (2) 80 to 90 parts by mass of the isocyanate prepolymer prepared in step (1), 7 to 13 parts by mass of a diamine chain extender, and 30 to 60 parts by mass of an epoxy resin are mixed in a solvent, dibutyltin dilaurate is added, the temperature is raised to 80 to 100° C., and the reaction is carried out for 3 to 5 hours to obtain a urea-modified epoxy resin.

[0023] The applicant has prepared a urea-modified epoxy resin, the structure of which contains a large number of polyurea segments, providing a large number of hydrogen bonds, thereby improving the intermolecular force with the fiber filaments, thereby making the urea-modified epoxy resin more adherent to the fiber filaments. In addition, it also has a large number of hydrogen bond receptors, which improve the intermolecular force with the modified nano-activated carbon, thereby making the urea-modified epoxy resin and the modified nano-activated carbon more adherent, making the acid-removing filter material more stable during use and less likely to fall off.

[0024] In some embodiments, the epoxy resin is one or more of diglycidyl phthalate, diglycidyl methyltetrahydrophthalate, bisphenol A epoxy resin, bisphenol S epoxy resin, and bisphenol F epoxy resin.

[0025] In some embodiments, the isocyanate compound is one or more of methylcyclohexyl diisocyanate, diethyl 2-isocyanate glutarate, hexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate, and isophorone diisocyanate.

[0026] Preferably, the isocyanate compound is isophorone diisocyanate.

[0027] In some embodiments, the diamine chain extender is one or more of 1,4-bis-sec-butylaminobenzene, 4,4'-bis-sec-butylaminodiphenylmethane, diethyltoluenediamine, bis-sec-butylaminodiphenylmethane, 3,5-dimethylthiotoluenediamine, and 3,3'-dichloro-4,4'-diaminophenylmethane.

[0028] In some embodiments, the number average molecular weight of the polyetheramine is 1000-6000.

[0029] In some embodiments, the molar ratio of the polyetheramine to the isocyanate compound is 1:(1.4-1.6).

[0030] Preferably, the molar ratio of the polyetheramine to the isocyanate compound is 1:1.5.

[0031] By adjusting the molar ratio of polyetheramine to isocyanate compounds, the applicant can make the isocyanate group serve as the end group of the isocyanate prepolymer, react with the diamine chain extender to provide more urea groups, thereby increasing the viscosity of the urea-modified epoxy resin.

[0032] In some embodiments, the catalyst is one or more of triethylamine, naphthylamine, benzimidazole and diethanolamine; and the molar ratio of the polyetheramine to the catalyst is 1:(1.8-2.2).

[0033] Preferably, the catalyst is triethylamine; and the molar ratio of the polyetheramine to the catalyst is 1:2.

[0034] In some embodiments, the solvent is one or more of tetrahydrofuran, toluene, and N,N-dimethylformamide.

[0035] Preferably, the solvent is toluene.

[0036] In some embodiments, in step (1), the volume of the solvent is 7 to 11 times the mass of the polyetheramine.

[0037] Preferably, in step (1), the volume of the solvent is 9 times the mass of the polyetheramine.

[0038] In some embodiments, in step (2), the volume of the solvent is 2 to 4 times the weight of the isocyanate prepolymer.

[0039] Preferably, in step (2), the volume of the solvent is 3 times the weight of the isocyanate prepolymer.

[0040] In some embodiments, the mass of the dibutyltin dilaurate is 0.01 to 0.03 times the total mass of the isocyanate prepolymer, the diamine chain extender, and the epoxy resin.

[0041] Preferably, the mass of the dibutyltin dilaurate is 0.02 times the total mass of the isocyanate prepolymer, the diamine chain extender and the epoxy resin.

[0042] In some embodiments, the method for preparing the modified nano-activated carbon comprises the following steps:

[0043] (a) placing nano-activated carbon in a microwave muffle furnace, introducing a mixture of carbon dioxide and water vapor, heating to 600-800° C., and activating for 1-2 hours to obtain porous nano-activated carbon;

[0044] (b) placing the porous nano-activated carbon in step (a) in a nitric acid solution having a mass fraction of 40-60%, heating it to 80-90° C., soaking it for 6-8 hours, then washing it with deionized water to a pH of 6-8, then soaking it in a hydrochloric acid solution having a mass fraction of 20-36%, heating it to 60-80° C., reacting it for 5-7 hours, and then washing it with deionized water to a pH of 6-8 to obtain a modified nano-activated carbon precursor;

[0045] (c) adding the modified nano-activated carbon precursor in step (b) to a mixture of a silane coupling agent and aqueous ammonia, heating to 80-100° C., stirring for 16-18 h, washing with deionized water to a pH of 6-8, and drying at 100-120° C. for 12-14 h to obtain modified nano-activated carbon.

[0046] In the past, activated carbon was used directly as a physical adsorption material, which easily reached adsorption saturation and caused desorption, resulting in secondary pollution. Conventional physical adsorption is not ideal for the adsorption of organic acidic gases. Nano-activated carbon has a large number of active groups such as hydroxyl, carboxyl and carbonyl groups on its surface, which provides a basis for the modification of activated carbon. The applicant prepared porous nano-activated carbon by calcining and activating nano-activated carbon in a mixture of carbon dioxide and water vapor. Its surface has a loose porous structure, which increases its adsorption capacity. In addition, a modified nano-activated carbon precursor was prepared by soaking it in nitric acid and hydrochloric acid. Its surface has chlorine elements, which are highly active, greatly improving the modifiable direction of the modified nano-activated carbon precursor.

[0047] The applicant prepared modified nano-activated carbon by modifying the modified nano-activated carbon precursor using a silane coupling agent and ammonia water. The modified nano-activated carbon has excellent hydrophobic properties and good solubility in urea-modified epoxy resin. The amino groups on the surface can produce chemical adsorption, which greatly improves the adsorption capacity of the acid removal filter material.

[0048] In some embodiments, the volume of the nitric acid solution is 8 to 12 times the mass of the porous nano-activated carbon, and the volume of the hydrochloric acid solution is 8 to 12 times the mass of the porous nano-activated carbon.

[0049] Preferably, the volume of the nitric acid solution is 10 times the mass of the porous nano-activated carbon, and the volume of the hydrochloric acid solution is 10 times the mass of the porous nano-activated carbon.

[0050] In some embodiments, the mass of the mixture of the silane coupling agent and ammonia water is 5 to 9 times the mass of the modified nano-activated carbon precursor.

[0051] Preferably, the mass of the mixture of the silane coupling agent and ammonia water is 7 times the mass of the modified nano-activated carbon precursor.

[0052] In some embodiments, the particle size of the nano-activated carbon is 10 to 50 nm.

[0053] In some embodiments, the molar ratio of the silane coupling agent to aqueous ammonia is 1:(1-2).

[0054] Preferably, the molar ratio of the silane coupling agent to aqueous ammonia is 1:1.5.

[0055] The applicant adjusted the molar ratio of the silane coupling agent and ammonia water to make the modified nano-activated carbon have moderate hydrophobicity and better adsorption capacity for acidic gases.

[0056] In some embodiments, the silane coupling agent is one or more of KH-172, KBM-1083, KBM-4803, NXH-139, KH-1331, and NXH-139.

[0057] Another aspect of the present invention provides a filter material for removing acidic gas obtained by the above preparation method.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] (1) The present invention prepares a filter material for removing acidic gases by soaking fiber filaments in urea-modified epoxy resin and then adhering modified nano-activated carbon to the surface of the fiber filaments by spraying. On the one hand, the acid-removing filter material improves the adsorption capacity of acidic gases through physical and chemical synergistic adsorption, and the components have good mutual solubility and high adhesion, and are not easy to fall off; on the other hand, the electrostatic effect of the fiber filaments can adsorb inorganic dust in the air, further improving the air purification effect; on the third hand, the acid-removing filter material of the present invention has good acid and alkali corrosion resistance. After use, the acid-containing ammonium salt on the surface of the modified nano-activated carbon can be deacidified by soaking in a weak alkaline solution to achieve the effect of reuse, and after adsorbing the acidic gas, the ammonium salt component is loaded on the surface of the modified nano-activated carbon, which is convenient for post-processing and has no secondary pollution.

[0060] (2) The present invention prepares a urea-modified epoxy resin having a large number of hydrogen bonds and hydrogen bond receptors, wherein the hydrogen bonds can generate an interaction force with the hydrogen bond receptors on the fiber filaments, thereby increasing the viscosity of the urea-modified epoxy resin and the fiber filaments; wherein the hydrogen bond receptors can generate an interaction force with the hydrogen bonds in the modified nano-activated carbon, thereby increasing the viscosity of the urea-modified epoxy resin and the modified nano-activated carbon, thereby allowing the modified nano-activated carbon to adhere to the surface of the fiber filaments through the urea-modified epoxy resin and not easily fall off.

[0061] (3) The present invention prepares a modified nano-activated carbon having a high specific surface area and having hydrophobic groups and amino groups on the surface. It is miscible with the system and can increase the adsorption capacity of acidic gases through the synergistic effect of physical adsorption and chemical adsorption. DETAILED DESCRIPTION

[0062] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all 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.

[0063] In the following preparation examples, embodiments and comparative examples, the polyetheramine has a number average molecular weight of 1000 and was purchased from Zhongshan Dixin Chemical Co., Ltd.; bisphenol A epoxy resin was purchased from Langfang Zhan'ao Environmental Protection Technology Co., Ltd.; nano-activated carbon was purchased from Henan Junfa Environmental Protection Technology Co., Ltd., with a particle size of 10 nm; KH-172 silane coupling agent was purchased from Shandong Yuanjin New Materials Co., Ltd.; S-395A polyurethane resin was purchased from Dongguan Xuanjing Plastic Raw Materials Co., Ltd.; silk fiber was purchased from Anping County Runhao Ethylene Plastic Factory; and polyester fiber was purchased from Henan Shengxing Environmental Protection Materials Co., Ltd.

[0064] Preparation Example 1

[0065] The preparation method of urea-modified epoxy resin comprises the following steps:

[0066] (1) 100 g (0.1 mol) of polyetheramine and 20.24 g (0.2 mol) of triethylamine were dissolved in 900 mL of toluene, and 33.34 g (0.15 mol) of isophorone diisocyanate was slowly added at 0°C. After the addition, the temperature was raised to 25°C and the mixture was reacted for 12 h to obtain an isocyanate prepolymer;

[0067] (2) 85 g of the isocyanate prepolymer prepared in step (1), 10 g of 1,4-bis-sec-butylaminobenzene and 45 g of bisphenol A epoxy resin were mixed in 255 mL of toluene, 2.8 g of dibutyltin dilaurate was added, the temperature was raised to 90° C., and the reaction was carried out for 4 h to obtain a urea-modified epoxy resin.

[0068] Preparation Example 2

[0069] The preparation method of the urea-modified epoxy resin is the same as that of Preparation Example 1, except that the amount of isophorone diisocyanate added is 25 g (0.11 mol).

[0070] Preparation Example 3

[0071] The preparation method of urea-modified epoxy resin is the same as that of Preparation Example 1, except that an equal amount of 1,4-butanediol is used instead of 1,4-bis-sec-butylaminobenzene.

[0072] Preparation Example 4

[0073] The preparation method of the urea-modified resin is the same as that of Preparation Example 1, except that an equal amount of S-395A polyurethane resin is used instead of bisphenol A epoxy resin.

[0074] Preparation Example 5

[0075] The preparation method of modified nano-activated carbon A comprises the following steps:

[0076] (a) 10 g of nano-activated carbon was placed in a microwave muffle furnace, a mixture of carbon dioxide and water vapor was introduced, the temperature was raised to 700°C, and activated for 1.5 h to obtain porous nano-activated carbon;

[0077] (b) 10 g of the porous nano-activated carbon in step (a) was placed in 100 mL of a 50% nitric acid solution at 85° C. for 7 h, then washed with deionized water to a pH of 7, then immersed in 100 mL of a 28% hydrochloric acid solution, heated to 70° C., reacted for 6 h, and then washed with deionized water to a pH of 7 to obtain a modified nano-activated carbon precursor;

[0078] (c) 10 g of the modified nano-activated carbon precursor in step (b) was added to a mixture of 64.16 g (0.229 mol) of KH-172 silane coupling agent and 5.84 g (0.343 mol) of ammonia water, heated to 90 ° C, stirred for 17 h, washed with deionized water to pH = 7, and dried at 110 ° C for 13 hours to obtain modified nano-activated carbon.

[0079] Preparation Example 6

[0080] The preparation method of modified nano-activated carbon B is the same as that of Preparation Example 5, except that 65.99 g (0.235 mol) of KH-172 silane coupling agent and 4.01 g (0.235 mol) of ammonia water are added.

[0081] Preparation Example 7

[0082] The preparation method of modified nano-activated carbon C comprises the following steps:

[0083] (a) 10 g of nano-activated carbon was placed in 100 mL of 50% nitric acid solution at 85°C for 7 h, then washed with deionized water to a pH of 7, then immersed in 100 mL of 28% hydrochloric acid solution, heated to 70°C, reacted for 6 h, and then washed with deionized water to a pH of 7 to obtain a modified nano-activated carbon precursor;

[0084] (b) 10 g of the modified nano-activated carbon precursor in step (a) was added to a mixture of 64.16 g (0.229 mol) of KH-172 silane coupling agent and 5.84 g (0.343 mol) of ammonia water, heated to 90 ° C, stirred for 17 h, washed with deionized water to pH = 7, and dried at 110 ° C for 13 hours to obtain modified nano-activated carbon.

[0085] Example 1

[0086] This embodiment provides a method for preparing a filter material for removing acidic gas, comprising the following steps:

[0087] S1, soaking polyester fiber with a diameter of 13 μm in urea-modified epoxy resin, ultrasonicating at a frequency of 35 kHz for 15 minutes, and then taking out to obtain pretreated fiber;

[0088] S2. The pretreated fiber filaments prepared in step S1 are laid flat to a thickness of 1 mm, and 0.6 mm thick modified nano-activated carbon A is evenly sprayed on the surface. The fiber filaments are cured at 70° C. for 6 h, and then stacked into a filter material with a thickness of 7 cm to obtain a filter material for removing acidic gases.

[0089] Among them, the urea-modified epoxy resin is prepared by Preparation Example 1, and the modified nano-activated carbon A is prepared by Preparation Example 5.

[0090] Example 2

[0091] This embodiment provides a method for preparing a filter material for removing acidic gas, comprising the following steps:

[0092] S1, soaking polyester fiber with a diameter of 5 μm in urea-modified epoxy resin, ultrasonicating at a frequency of 20 kHz for 10 minutes, and then taking out to obtain pretreated fiber;

[0093] S2. The pretreated fiber filaments prepared in step S1 are laid flat to a thickness of 0.5 mm, and a 0.5 mm thick modified nano-activated carbon A is evenly sprayed on the surface. The fiber filaments are cured at 60° C. for 4 h, and then stacked into a filter material with a thickness of 7 cm to obtain a filter material for removing acidic gases.

[0094] Among them, the urea-modified epoxy resin is prepared by Preparation Example 1, and the modified nano-activated carbon A is prepared by Preparation Example 5.

[0095] Example 3

[0096] This embodiment provides a method for preparing a filter material for removing acidic gas, comprising the following steps:

[0097] S1, soaking polyester fiber with a diameter of 20 μm in urea-modified epoxy resin, ultrasonicating at a frequency of 50 kHz for 20 minutes, and then taking out to obtain pretreated fiber;

[0098] S2. The pretreated fiber filaments prepared in step S1 are laid flat to a thickness of 1.5 mm, and a 0.7 mm thick modified nano-activated carbon A is evenly sprayed on the surface. The fiber filaments are cured at 80° C. for 8 h, and then stacked into a filter material with a thickness of 7 cm to obtain a filter material for removing acidic gases.

[0099] Among them, the urea-modified epoxy resin is prepared by Preparation Example 1, and the modified nano-activated carbon A is prepared by Preparation Example 5.

[0100] Example 4

[0101] This embodiment provides a method for preparing a filter material for removing acidic gas. The specific implementation method is the same as that of Example 1, except that silk fiber is used instead of polyester fiber.

[0102] Example 5

[0103] This embodiment provides a method for preparing a filter material for removing acidic gases. The specific implementation method is the same as that of Example 1, except that the urea-modified epoxy resin is prepared according to Preparation Example 2.

[0104] Example 6

[0105] This embodiment provides a method for preparing a filter material for removing acidic gases. The specific implementation method is the same as that of Example 1, except that the urea-modified epoxy resin is prepared according to Preparation Example 3.

[0106] Example 7

[0107] This embodiment provides a method for preparing a filter material for removing acidic gases. The specific implementation method is the same as that of Example 1, except that modified nano-activated carbon B of equal mass is used instead of modified nano-activated carbon A, and modified nano-activated carbon B is prepared by Preparation Example 6.

[0108] Example 8

[0109] This embodiment provides a method for preparing a filter material for removing acidic gases. The specific implementation method is the same as that of Example 1, except that modified nano-activated carbon C of equal mass is used instead of modified nano-activated carbon A, and modified nano-activated carbon C is prepared by Preparation Example 7.

[0110] Comparative Example 1

[0111] This comparative example provides a method for preparing a filter material for removing acidic gases. The specific implementation method is the same as that of Example 1, except that an equal mass of bisphenol A epoxy resin is used instead of urea-modified epoxy resin.

[0112] Comparative Example 2

[0113] This comparative example provides a method for preparing a filter material for removing acidic gas. The specific implementation method is the same as that of Example 1, except that activated carbon of equal mass is used instead of modified nano-activated carbon.

[0114] Comparative Example 3

[0115] This comparative example provides a method for preparing a filter material for removing acidic gas. The specific implementation method is the same as that of Example 1, except that a urea-modified resin is used instead of a urea-modified epoxy resin. The urea-modified resin is prepared by Preparation Example 4.

[0116] Performance testing:

[0117] 1. Fracture toughness test: The test was conducted in accordance with ASTM D5045, Standard Test Method for Plane Strain Fracture Toughness and Strain Energy Release Rate of Plastic Materials. The test was conducted on a Wance ETM104B-EX electronic universal testing machine with a 2000N gravity sensor.

[0118] 2. Desulfurization efficiency test: With hydrogen sulfide as the main acid gas, a cylindrical glass tube with a length of 10 cm and an inner diameter of 10 mm was used as an adsorption column. The filter material for removing acidic gas was placed in the adsorption column and the air velocity was 1000 h -1 A standard gas of 2000ppm hydrogen sulfide was introduced, and the hydrogen sulfide content at the inlet and outlet was tested with an SCD detector to calculate the desulfurization efficiency;

[0119] 3. Initial adsorption capacity and adsorption capacity after 20 cycles: In the desulfurization efficiency test, when the concentration of hydrogen sulfide at the outlet reaches 10% of its original concentration, it is considered to have broken through. The calculated breakthrough sulfur capacity is considered to be the adsorption capacity of the acid gas removal filter material. After hydrogen sulfide breakthrough, the acid gas removal filter material is soaked in a 3 mol / L sodium carbonate solution for 24 hours, which is considered to be one cycle. In this way, the acid gas removal filter material that has been recycled 20 times is obtained.

[0120] 4. Dust removal efficiency test: According to the MT / T712 "Determination of the graded dust removal efficiency of dust control measures in coal mines", the calculation formula is: Dust removal efficiency = (total dust concentration - total dust concentration after dust control) / total dust concentration × 100%;

[0121] 5. Stability test: After the desulfurization efficiency test, observe whether the surface of the filter material for removing acidic gas shows any fogging, cracking, bubbling or stickiness. If the above phenomena exist, it is considered "unstable". If not, it is considered "stable".

[0122] The filter materials prepared in the examples and comparative examples were cut into squares with a length of 10 cm and a width of 10 cm, and stacked into filter materials with a thickness of 7 cm. The filter materials were tested according to the above test method. The test results are shown in Table 1.

[0123] Table 1

[0124]

[0125]

[0126] It can be seen from Table 1 that the filter materials for removing acidic gas prepared in Examples 1 to 3 have good fracture toughness and stability, good adsorption effect on hydrogen sulfide, large adsorption capacity, and good adsorption capacity for smoke dust; Example 4 uses silk instead of polyester fiber, so that the filter material prepared has no electrostatic effect, resulting in a weakened adsorption capacity for smoke dust; Example 5 changes the molar ratio of polyetheramine and isophorone diisocyanate, so that the urea content in the prepared urea-modified epoxy resin is reduced, the hydrogen bonding force is weakened, and the prepared The fracture toughness of the prepared filter material is reduced; in Example 6, due to the change in the type of chain extender, the urea content in the prepared urea-modified epoxy resin is reduced, the hydrogen bonding force is weakened, and the fracture toughness of the prepared filter material is reduced; in Example 7, due to the change in the molar ratio of KH-172 silane coupling agent and ammonia water, the groups that adsorb hydrogen sulfide in the nano-activated carbon are reduced, resulting in a decrease in the desulfurization efficiency and initial adsorption capacity of the filter material; in Example 8, due to the lack of calcination of the nano-activated carbon, the modified nano-activated carbon does not have a loose porous structure and the specific surface area is not increased, resulting in The desulfurization efficiency and initial adsorption capacity of the prepared filter material are reduced; in Comparative Example 1, bisphenol A epoxy resin is used instead of urea-modified epoxy resin. The epoxy group in the conventional epoxy resin has poor acid and alkali resistance and weak hydrogen bonding force, which leads to a decrease in the fracture toughness of the filter material. At the same time, the viscosity of the epoxy resin decreases after adsorbing acidic gas, and the modified nano-activated carbon falls off, resulting in a decrease in the adsorption capacity after the filter material is recycled for 20 times. In addition, the filter material is unstable; in Comparative Example 2, the nano-activated carbon is not modified, and its chemical adsorption capacity is large. The surface area is greatly weakened, and the surface area is low, resulting in a decrease in the desulfurization efficiency and initial adsorption capacity of the prepared filter material, and it cannot be recycled many times. In addition, due to the presence of its surface hydrophilic structure, it forms hydrogen bonds with moisture in the air, and moisture enters the interior of the filter material, causing the filter material to become unstable. In Comparative Example 3, since the urea-modified resin replaces the urea-modified epoxy resin, its acid resistance is weak. After adsorbing hydrogen sulfide gas, it decomposes and its viscosity decreases, causing the modified nano-activated carbon to fall off, resulting in a decrease in adsorption capacity after 20 cycles, and an unstable phenomenon. The test results show that the filter material for removing acidic gases prepared by the present invention has good fracture toughness, good acid-base stability, good adsorption effect on acidic gases and smoke, and can be recycled repeatedly.

[0127] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a filter material for removing acidic gas, characterized in that: The steps include: S1, soaking the fiber in urea-modified epoxy resin, ultrasonicating for 10-20 minutes, and then taking it out to obtain pretreated fiber; S2. Lay the pretreated fiber filaments prepared in step S1 flat, spray the modified nano-activated carbon evenly with a thickness of 0.5-0.7 mm on the surface, cure at 60-80° C. for 4-8 hours, and then stack them into a filter material with a thickness of 7 cm or more to obtain a filter material for removing acidic gas; The fiber filaments are one or more of polyester fiber filaments, nylon fiber filaments and polypropylene fiber filaments, and the fiber filaments have a diameter of 5 to 20 μm; The preparation method of the urea-modified epoxy resin comprises the following steps: (1) Dissolve the polyetheramine and catalyst in a solvent, slowly add the isocyanate compound at -5~5°C, raise the temperature to 20~30°C and react for 10~14h to obtain an isocyanate prepolymer; (2) 80-90 parts by mass of the isocyanate prepolymer prepared in step (1), 7-13 parts by mass of a diamine chain extender, and 30-60 parts by mass of an epoxy resin are mixed in a solvent, dibutyltin dilaurate is added, the temperature is raised to 80-100° C., and the reaction is carried out for 3-5 hours to obtain a urea-modified epoxy resin; The preparation method of the modified nano-activated carbon comprises the following steps: (a) Nano-activated carbon was placed in a microwave muffle furnace, a mixture of carbon dioxide and water vapor was introduced, the temperature was raised to 600-800°C, and activated for 1-2 hours to obtain porous nano-activated carbon; (b) placing the porous nano-activated carbon in step (a) in a nitric acid solution with a mass fraction of 40-60%, heating it to 80-90°C, soaking it for 6-8 hours, then washing it with deionized water to a pH of 6-8, then soaking it in a hydrochloric acid solution with a mass fraction of 20-36%, heating it to 60-80°C, reacting it for 5-7 hours, and then washing it with deionized water to a pH of 6-8 to obtain a modified nano-activated carbon precursor; (c) adding the modified nano-activated carbon precursor in step (b) to a mixture of a silane coupling agent and aqueous ammonia, heating the mixture to 80-100°C, stirring the mixture for 16-18 hours, washing the mixture with deionized water to a pH of 6-8, and drying the mixture at 100-120°C for 12-14 hours to obtain modified nano-activated carbon.

2. The method for preparing a filter material for removing acidic gas according to claim 1, characterized in that: The ultrasonic frequency is 20-50 kHz.

3. The method for preparing a filter material for removing acidic gas according to claim 1, characterized in that: The thickness of the pretreated fiber filaments when laid flat is 0.5-1.5 mm.

4. The method for preparing a filter material for removing acidic gas according to claim 1, characterized in that: The molar ratio of the polyetheramine to the isocyanate compound is 1:(1.4-1.6).

5. The method for preparing a filter material for removing acidic gas according to claim 1, characterized in that: The mass of the dibutyltin dilaurate is 0.01 to 0.03 times the total mass of the isocyanate prepolymer, the diamine chain extender and the epoxy resin.

6. The method for preparing a filter material for removing acidic gas according to claim 1, characterized in that: The molar ratio of the silane coupling agent to the ammonia water is 1:(1-2).

7. A filter material for removing acidic gas obtained by the preparation method according to any one of claims 1 to 6.

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