Air purification material for removing alkaline contaminants in air and preparation method and application thereof

Abstract

The application discloses an air purification material for removing alkaline pollutants in air and a preparation method and application thereof, and comprises the following steps: (1) active ingredients and a binder are added with water to form an aqueous solution, and then the aqueous solution is uniformly mixed with a porous carrier and a biomass-based pore-forming agent, granulated, dried, and active particles are prepared; (2) the active particles are treated by high-temperature and oxygen-deficient calcination, the biomass-based pore-forming agent is carbonized, and finally water spraying and humidification are carried out, the moisture is balanced after humidification, and the air purification material is prepared. By introducing the biomass-based pore-forming agent, the large pore channel is constructed through the oxygen-deficient calcination process, the porous structure of the material is reconstructed, the purification efficiency and the treatment capacity are simultaneously improved, the ammonia treatment capacity exceeds 10% of the mass of the material, and can reach more than 3 times of the commercial phosphoric acid modified activated carbon air purification material; and the air purification material prepared by the application has high safety, can tolerate direct irradiation of a butane spray lamp for 30 seconds, and the material has no open flame, no smoldering, and no smoke release.

Description

An air purification material for removing alkaline pollutants from the air, its preparation method and application Technical Field

[0001] This invention belongs to the field of air purification materials technology, and relates to an air purification material for removing alkaline pollutants from the air, its preparation method and application. Background Technology

[0002] In recent years, ammonia emissions have increased significantly with population growth and accelerated urbanization. Its harm to the environment and human health has attracted widespread attention worldwide, leading to the introduction of strict standards to limit ammonia emissions. It is generally accepted that the time-weighted concentration of ammonia should be less than 25 ppm.

[0003] Currently, there are four main technologies for ammonia removal: catalytic oxidation, biological methods, absorption, and adsorption. While noble metal-based catalysts in catalytic oxidation exhibit high low-temperature catalytic activity and resistance to deactivation, ammonia-containing odorous gases emitted from industrial flue gas often contain oils and other substances that can poison the catalyst. This results in high costs for removing ammonia from high-temperature waste gas, making them unsuitable for ammonia removal in high-temperature environments and industrial applications. Non-noble metal-based catalysts also have limitations in selectivity and catalyst stability.

[0004] Biological methods can completely remove ammonia at room temperature, but they have a low gas throughput and microorganisms are easily affected by toxic substances. High concentrations of ammonia can disrupt the treatment process. Although some bioreactors (such as biofilters) have high ammonia removal efficiency, their ammonia removal efficiency will decrease when the inlet NH3 compliance rate (NLR) is higher than 10-20 gN / (m3·h).

[0005] Ammonia removal by absorption is mainly divided into physical absorption and chemical absorption. Physical absorption primarily involves dissolving pollutants in water and removing them through simple physical absorption, but its efficiency is low. Chemical absorption, on the other hand, uses appropriate chemical agents to react with the pollutants, increasing the solvent's absorption capacity for the pollutant gas. However, absorption methods typically have disadvantages such as high maintenance costs and the need for secondary treatment.

[0006] Adsorption-based ammonia removal refers to the purification of ammonia by adsorbing ammonia molecules from the gas onto the surface of a solid adsorbent. Common adsorbents include zeolite molecular sieves, alumina, silica gel, and activated carbon. However, these methods suffer from drawbacks such as weak selectivity for pollutants, limited adsorption capacity, and easy desorption of adsorbed pollutants at high temperatures, resulting in low ammonia removal efficiency in practical applications. Acid-modified activated carbon utilizes physical adsorption and acid-base neutralization to improve ammonia removal capacity, but only by about 3%. Furthermore, modified activated carbon is flammable, posing a safety hazard. Other modified adsorbent materials can increase the adsorption efficiency of ammonia by increasing the number of surface functional groups, but this requires a long adsorption time and the adsorption capacity is not high. For example, invention patent CN115722214B discloses an ammonia removal resin material and its preparation method, including the preparation of S1 modified cellulose, S2 adsorbent, and S3 resin material. Although it can increase the adsorption efficiency of ammonia to over 99%, the adsorption process takes 60 minutes and the adsorption capacity is less than 0.1%, making it impractical for application. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides an air purification material for removing acidic pollutants from the air, its preparation method, and its application. By introducing a biomass-based pore-forming agent and constructing macroporous channels through an oxygen-deficient calcination process, the porous structure of the material is reconstructed, increasing the contact area between the active ingredients and ammonia gas, improving reaction efficiency, and simultaneously enhancing purification efficiency and processing capacity while improving safety, thus solving the pain points of the dry ammonia removal industry.

[0008] The technical solution of the present invention is as follows:

[0009] A method for preparing an air purification material for removing alkaline pollutants from the air, comprising the following steps:

[0010] (1) Add water to the active ingredient and binder to make an aqueous solution, then mix it evenly with the porous carrier and biomass-based pore-forming agent, granulate, and dry to obtain active particles; or add water to the binder to make an aqueous solution, then mix it evenly with the porous carrier, active ingredient and biomass-based pore-forming agent, granulate, and dry to obtain active particles.

[0011] (2) The active particles are calcined at high temperature in an oxygen-deficient environment to carbonize and form pores in the biomass-based pore-forming agent.

[0012] (3) Spray water to humidify, then seal to balance the moisture to obtain air purification material.

[0013] After granulation in step (1), depending on the size of the product particles (0.5-6mm), standard sieves of different mesh sizes are used for sieving as needed.

[0014] Preferably, the air purification material comprises, by mass percentage: 20-80% porous carrier; 5-50% active ingredient; 0.5-5% binder; 1-10% biomass-based pore-forming agent; and 5-20% moisture. The porous carrier includes activated alumina and / or activated carbon. The active ingredient includes one or more of copper sulfate, zinc chloride, and magnesium chloride.

[0015] Preferably, the porous carrier comprises 20-60% activated alumina and 5-30% activated carbon by mass percentage in the air purification material, with a total content of 25-70%.

[0016] Preferably, the active ingredients comprise 0-50% zinc chloride, 0-50% copper sulfate, and 0-50% magnesium chloride by mass percentage in the air purification material, with a total content of 10-50%.

[0017] Preferably, the biomass-based pore-forming agent is sawdust or cotton fiber. Cotton fiber consists of uniform filaments with a diameter of approximately 20 μm, and its composition includes over 90% cellulose. Cellulose decomposes easily within the 300-400℃ range and begins to carbonize above 400℃, easily forming uniform channels. The sawdust has a particle size of approximately 200 mesh, with a diameter close to 80 μm. Besides cellulose, its composition includes 20-30% lignin. Lignin decomposes at 300-500℃ and only begins to carbonize above 500℃. A small amount of residual lignin can support the channels and prevent large channels from collapsing.

[0018] Preferably, the binder is sodium carboxymethyl cellulose.

[0019] Preferably, the air purification material comprises, by mass percentage: 40-70% porous carrier; 10-40% active ingredient; 1-5% binder; 5-10% biomass-based pore-forming agent; and 5-15% moisture.

[0020] Preferably, the high-temperature oxygen-deficient calcination treatment is performed at a temperature of 400±100℃ for a time of 3±1h.

[0021] The application of air purification materials prepared by the above method in removing alkaline pollutants from the air.

[0022] Penetration tests showed a significant improvement in its ammonia adsorption and decomposition capacity. The underlying mechanism is that the high-temperature, oxygen-deficient calcination process carbonizes the sawdust in the formula, releasing pores that allow the effective components inside and outside the particles to react with alkaline pollutants. Ammonia is adsorbed into the micropores of the air purification material. Since the micropores contain moisture, the ammonia dissolves in the water to form ammonia water (NH3·H2O). The ammonia water then undergoes weak hydrolysis to generate hydroxide ions (OH-). - ) and ammonium ions (NH4+)4+ Zinc chloride (ZnCl2) reacts with ammonia to form zinc hydroxide (Zn(OH)2) precipitate and ammonium chloride (NH4Cl). Zinc hydroxide then reacts with ammonia to form a tetraamminezinc complex ion [Zn(NH3)4]. 2+ Copper sulfate (CuSO4) reacts with ammonia to form copper hydroxide (Cu(OH)2) precipitate and ammonium sulfate ((NH4)2SO4). Copper hydroxide reacts with ammonia gas to form tetraamminecopper complex ion [Cu(NH3)4]. 2+ Magnesium chloride (MgCl2) reacts with ammonia to produce magnesium hydroxide (Mg(OH)2) precipitate and ammonium chloride (NH4Cl).

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) Structural synergy: Biomass-based pore-forming agent decomposes at high temperature to form interconnected micropores, which increases the diffusion rate of ammonia in the air purification material and improves the adsorption and decomposition efficiency and treatment capacity of ammonia; Sodium carboxymethyl cellulose binder forms a three-dimensional network skeleton structure during low-temperature calcination, which ensures the structural strength of the air purification material.

[0025] (2) Performance advantages: High processing capacity. Referring to the determination method of penetration capacity and penetration time of activated carbon adsorption of hydrogen sulfide in MT / T 1067-2008, the air purification material prepared by this invention has an ammonia processing capacity of more than 10% of its own mass, which is more than 3 times that of commercially available phosphoric acid modified activated carbon air purification materials; High safety. The air purification material prepared by this patent invention can withstand 30 seconds of direct erosion by a butane torch, and the material has no open flame, no smoldering, and no smoke release. Attached Figure Description

[0026] Figure 1 is a photograph of the air purification material of Embodiment 5 of the present invention.

[0027] Figure 2 is a test diagram of the burn resistance of the air purification material in Embodiment 5 of the present invention. The upper figure is a diagram of the state during burning, and the lower figure is a diagram of the state after the flame is turned off. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto. For process parameters not specifically noted, conventional techniques can be referred to.

[0029] The butane torch used in this invention is the Explorer brand TXZ-QTQTQT model, with a flame temperature of approximately 900–1300°C.

[0030] The activated carbon was GH-81 coconut shell activated carbon powder purchased from Tianjin Guanghua Jingke Environmental Protection Technology Co., Ltd.

[0031] Example 1

[0032] Preparation of air purification materials: The powder is prepared according to the following mass percentages: 50% activated alumina, 20% activated carbon, and 1% sawdust. Zinc chloride and sodium carboxymethyl cellulose are dissolved in water to prepare an aqueous solution. The prepared powder and aqueous solution are thoroughly mixed, controlling the zinc chloride content to 10% and the sodium carboxymethyl cellulose content to 0.5%. Granulation is performed using a granulator, and particles with a diameter of 10-20 mesh are sieved using a standard sieve. The sieved particles are dried at 130℃ to constant weight, and then calcined at 400℃ in an oxygen-deficient environment for 3 hours. After calcination, the particles are sprayed with water for humidification and equilibration, controlling the moisture content to 18.5%.

[0033] Performance testing of air purification materials: Referring to MT / T 1067-2008, the method for determining the penetration capacity and penetration time of activated carbon adsorbing hydrogen sulfide, hydrogen sulfide was replaced with ammonia. The test was conducted at room temperature with a total flow rate of 1500 mL / min for the ammonia-air mixture and an ammonia concentration of 10000 ppm. The test was stopped when the ammonia concentration at the end of the test tube reached 50 ppm. The removal efficiency remained ≥99.5%, and the penetration time was recorded as 594 min. The ammonia penetration capacity of the air purification material prepared in the above examples was measured to be 5.2%. A fire resistance test was performed on the air purification material prepared in the above examples. The air purification material was directly burned with a butane torch flame for 30 seconds. After removing the torch flame, the air purification material produced no flame or smoke.

[0034] The penetration capacity of ammonia is:

[0035]

[0036] In the formula:

[0037] C—Penetrating capacity of ammonia, expressed in grams per gram (g / g);

[0038] C Q —The volume percentage of ammonia in the test gas, expressed as a percentage (%);

[0039] V Z —Total flow rate of the test gas, in milliliters per minute (mL / min);

[0040] T—Total penetration test time, in minutes (min);

[0041] 17 — Molar mass of ammonia, in grams per mole (g / mol);

[0042] 22.4 — Molar volume of ammonia under standard conditions, in liters per mole (L / mol);

[0043] m G—Penetrating test sample mass, in grams (g).

[0044] Referring to the air purification material preparation method in Example 1, different air purification materials were prepared by adjusting the proportions of each component. The specific preparation conditions are shown in Tables 1-1 and 1-2 below.

[0045] Table 1-1

[0046]

[0047]

[0048] Table 1-2

[0049]

[0050] Referring to the air purification material performance test conditions in Example 1, the air purification materials prepared in each of the examples in the table were tested, and the test results are shown in Table 2 below.

[0051] Table 2

[0052]

[0053]

[0054] Comparative Example 1

[0055] Compared with Example 5, this one did not undergo calcination at 400°C in an oxygen-deficient environment.

[0056] Preparation of air purification materials: The powder is prepared according to the following mass percentages: 40% activated alumina, 20% activated carbon, and 8% sawdust. Zinc chloride and sodium carboxymethyl cellulose are dissolved in water to prepare an aqueous solution. The prepared powder and aqueous solution are thoroughly mixed, controlling the zinc chloride content to 20% and the sodium carboxymethyl cellulose content to 2%. Granulation is performed using a granulator, followed by sieving using a standard sieve. The sieved particles are then dried at 130℃ until the moisture content reaches 10%.

[0057] Performance testing of air purification materials: Referring to MT / T 1067-2008, the method for determining the penetration capacity and penetration time of activated carbon adsorbing hydrogen sulfide, hydrogen sulfide was replaced with ammonia. Testing was conducted at room temperature with a total flow rate of 1500 mL / min for the ammonia-air mixture. The ammonia concentration at the inlet of the penetration test tube was 10000 ppm. The test was stopped when the ammonia concentration at the outlet of the test tube reached 50 ppm. The removal efficiency remained ≥99.5%, and the penetration time was recorded as 408 min. The ammonia penetration capacity of the air purification material prepared in the above examples was measured to be 3.2%. A fire resistance test was performed on the air purification material prepared in the above examples. The air purification material was directly burned with a butane torch flame for 30 seconds. After removing the torch flame, the air purification material produced no flame or smoke.

[0058] Comparative Example 2

[0059] Compared with Example 5, no wood chips, which are pore-forming components, were added.

[0060] Preparation of air purification materials: Powder is prepared using 40% activated alumina and 20% activated carbon by mass percentage. Zinc chloride and sodium carboxymethyl cellulose are dissolved in water to prepare an aqueous solution. The prepared powder is thoroughly mixed with the aqueous solution, controlling the zinc chloride content to 20% and the sodium carboxymethyl cellulose content to 2%. Granulation is performed using a granulator, followed by sieving using a standard sieve. The sieved particles are dried at 130℃ to constant weight, then calcined at 400℃ in an oxygen-deficient environment for 3 hours. After calcination, the particles are sprayed with water for humidification and equilibration, controlling the moisture content to 18%.

[0061] Performance testing of air purification materials: Referring to MT / T 1067-2008, the method for determining the penetration capacity and penetration time of activated carbon adsorbing hydrogen sulfide, hydrogen sulfide was replaced with ammonia. Testing was conducted at room temperature with a total flow rate of 1500 mL / min for the ammonia-air mixture. The ammonia concentration at the inlet of the penetration test tube was 10000 ppm, and the test was stopped when the ammonia concentration at the outlet of the test tube reached 50 ppm. The removal efficiency remained ≥99.5%, and the penetration time was recorded as 443 min. The ammonia penetration capacity of the air purification material prepared in the above examples was measured to be 3.6%. A fire resistance test was performed on the air purification material prepared in the above examples. The air purification material was directly burned with a butane torch flame for 30 seconds. After removing the torch flame, the air purification material produced no flame or smoke.

[0062] Comparative Example 3

[0063] Compared with Example 5, no porous carrier activated carbon was added.

[0064] Preparation of air purification materials: Powder is prepared by mixing 60% activated alumina and 8% sawdust by mass percentage. Zinc chloride and sodium carboxymethyl cellulose are dissolved in water to prepare an aqueous solution. The prepared powder and aqueous solution are thoroughly mixed, controlling the zinc chloride content to 20% and the sodium carboxymethyl cellulose content to 2%. Granulation is performed using a granulator, followed by sieving using a standard sieve. The sieved particles are dried at 130℃ to constant weight, then calcined at 400℃ in an oxygen-deficient environment for 3 hours. After calcination, the particles are sprayed with water for humidification and equilibration, controlling the moisture content to 10%.

[0065] Performance testing of air purification materials: Referring to MT / T 1067-2008, the method for determining the penetration capacity and penetration time of activated carbon adsorbing hydrogen sulfide, hydrogen sulfide was replaced with ammonia. Testing was conducted at room temperature with a total flow rate of 1500 mL / min for the ammonia-air mixture. The ammonia concentration at the inlet of the penetration test tube was 10000 ppm, and the test was stopped when the ammonia concentration at the outlet of the test tube reached 50 ppm. The removal efficiency remained ≥99.5%, and the penetration time was recorded as 592 min. The ammonia penetration capacity of the air purification material prepared in the above examples was measured to be 4.5%. A fire resistance test was performed on the air purification material prepared in the above examples. The air purification material was directly burned with a butane torch flame for 30 seconds. After removing the torch flame, the air purification material produced no flame or smoke.

[0066] Comparative Example 4

[0067] Purchase commercially available 5% phosphoric acid impregnated activated carbon and test its ammonia penetration capacity and fire resistance.

[0068] Referring to MT / T 1067-2008, "Determination of Transmission Capacity and Transmission Time of Activated Carbon Adsorption of Hydrogen Sulfide," hydrogen sulfide was replaced with ammonia. The test was conducted at room temperature with a total flow rate of 1500 mL / min for the ammonia-air mixture, an initial ammonia concentration of 10000 ppm, and a final ammonia concentration of 50 ppm. The removal efficiency remained ≥99.5%, and the transmission time was recorded as 371 min. The ammonia transmission capacity of commercially available 5% phosphoric acid impregnated activated carbon was measured to be 3.7%. A fire resistance test was performed on the commercially available 5% phosphoric acid impregnated activated carbon. It was directly burned with a butane torch flame for 30 seconds. After the torch flame was removed, the commercially available 5% phosphoric acid impregnated activated carbon continued to burn, releasing fumes.

[0069] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing an air purification material for removing alkaline pollutants from the air, characterized in that, The process includes the following steps: (1) Add water to the active ingredient and binder to make an aqueous solution, then mix it evenly with the porous carrier and biomass-based pore-forming agent, granulate, dry, and obtain active particles; or add water to the binder to make an aqueous solution, then mix it evenly with the porous carrier, active ingredient and biomass-based pore-forming agent, granulate, dry, and obtain active particles; the binder is sodium carboxymethyl cellulose; (2) Calcine the active particles at high temperature in an oxygen-deficient environment at a temperature of 400±100℃ to carbonize and form pores in the biomass-based pore-forming agent; (3) Humidify by spraying water, then seal and balance the moisture to obtain air purification material; the composition of the air purification material is as follows: by mass percentage, porous carrier 20-80%; active ingredient 5-50%; binder 0.5-5%; biomass-based pore-forming agent 1-10%; moisture 5-20%; the porous carrier includes activated alumina and activated carbon; the active ingredient includes one or more of copper sulfate, zinc chloride and magnesium chloride.

2. The preparation method according to claim 1, characterized in that, The porous carrier comprises 20-60% activated alumina and 5-30% activated carbon by mass percentage in the air purification material, with a total content of 25-70%.

3. The preparation method according to claim 1, characterized in that, The active ingredients, by mass percentage in the air purification material, include 0-50% zinc chloride, 0-50% copper sulfate, and 0-50% magnesium chloride, with a total content of 10-50%.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The biomass-based pore-forming agent is wood chips or cotton fiber.

5. The preparation method according to any one of claims 1 to 3, characterized in that, The air purification material comprises, by mass percentage: 40-70% porous carrier; 10-40% active ingredient; 1-5% binder; 5-10% biomass-based pore-forming agent; and 5-15% moisture.

6. The preparation method according to any one of claims 1 to 3, characterized in that, The high-temperature oxygen-deficient calcination treatment time is 3±1h.

7. The air purification material prepared by the method according to any one of claims 1 to 6.

8. The application of the air purification material according to claim 7 in removing alkaline pollutants from the air.

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