Air purification material for removing alkaline pollutants in air as well as preparation method and application of air purification material

Abstract

The invention discloses an air purification material for removing alkaline pollutants in air and a preparation method and application thereof, and the preparation method comprises the following steps: (1) adding water into an active component and a binder to prepare an aqueous solution, uniformly mixing the aqueous solution with a porous carrier and a biomass-based pore-forming agent, granulating, and drying to prepare active particles; and (2) carrying out high-temperature anoxic calcination treatment on the active particles to carbonize the biomass-based pore-forming agent, finally spraying water to humidify, and sealing to balance moisture after humidifying, thereby obtaining the air purification material. The biomass-based pore-forming agent is introduced, a macroporous channel is constructed through an anoxic calcination process, a porous structure of the material is reconstructed, the purification efficiency and the treatment capacity are synchronously improved, and the ammonia gas treatment capacity exceeds 10% of the mass of the ammonia gas and can reach more than three times of that of a commercially available phosphoric acid modified activated carbon air purification material; the air purification material prepared by the preparation method disclosed by the invention can tolerate 30-second ablation caused by direct injection of a butane blast burner, and is free of open fire, smoldering and smoke release.

Description

Technical Field

[0001] The present invention belongs to the technical field of air purification materials, and relates to an air purification material for removing alkaline pollutants in the air, and a preparation method and application thereof. Background Art

[0002] In recent years, ammonia emissions have been increasing significantly, driven by population growth and urbanization. Its impact on the environment and human health has garnered widespread attention worldwide, leading to the introduction of stringent emission limits. It is generally accepted that ammonia concentrations should be less than 25 ppm on a time-weighted basis.

[0003] Currently, the main technologies used for ammonia removal include catalytic oxidation, biological methods, absorption methods, and adsorption methods. While precious metal-based catalysts in catalytic oxidation methods offer high low-temperature catalytic activity and resistance to deactivation, ammonia-containing odorous gases, such as industrial flue gases, often carry substances such as oils, which can easily poison the catalysts. This results in high costs for removing high-temperature ammonia-containing waste gases, making them unsuitable for high-temperature ammonia removal and industrial applications. Non-precious metal-based catalysts also have limitations in terms of selectivity and stability.

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

[0005] Absorption-based deamination is primarily categorized into physical absorption and chemical absorption. Physical absorption involves dissolving pollutants in water and removing them through simple physical absorption, which is inefficient. Chemical absorption, on the other hand, involves using appropriate chemicals to react with the pollutants, increasing the solvent's ability to absorb the pollutant gas. However, absorption methods often have drawbacks such as high maintenance costs and the need for secondary treatment.

[0006] Adsorption deamination refers to the process of purifying ammonia by adsorbing ammonia molecules from a gas onto the surface of a solid adsorbent using a solid adsorbent. Common adsorbents include zeolite molecular sieves, alumina, silica gel, and activated carbon. These have disadvantages such as weak selectivity for pollutants, limited adsorption capacity, and the easy decomposition 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 its ammonia removal capacity, but it is only about 3%, and the modified activated carbon material is flammable, posing a safety hazard. Other modified adsorbent materials can improve ammonia adsorption efficiency by increasing the number of surface functional groups, but this requires a longer adsorption time and the adsorption capacity is not high. For example, the invention patent with publication number CN115722214B discloses an ammonia removal resin material and its preparation method, including the preparation of S1 modified cellulose, the preparation of S2 adsorbent, and the preparation of S3 resin material. Although the ammonia adsorption efficiency can be increased to more than 99%, the adsorption process takes 60 minutes and the adsorption capacity is less than 0.1%, making it impractical for practical application. Summary of the Invention

[0007] To address the aforementioned technical issues, the present invention provides an air purification material for removing acidic pollutants from the air, as well as its preparation method and application. By introducing a biomass-based pore former and constructing macroporous channels through an anoxic calcination process, the material's porous structure is reconstructed, increasing the contact area between the active ingredient and ammonia, improving reaction efficiency, and simultaneously enhancing purification efficiency, processing capacity, and safety, thereby addressing key issues in the dry ammonia removal industry.

[0008] The technical solutions of the present invention are as follows:

[0009] A method for preparing an air purification material for removing alkaline pollutants in the air comprises the following steps:

[0010] (1) adding water to the active ingredient and the binder to form an aqueous solution, then uniformly mixing the solution with the porous carrier and the biomass-based pore-forming agent, granulating, and drying to obtain active granules; or adding water to the binder to form an aqueous solution, then uniformly mixing the solution with the porous carrier, the active ingredient, and the biomass-based pore-forming agent, granulating, and drying to obtain active granules;

[0011] (2) calcining the active particles at high temperature and in the absence of oxygen to carbonize the biomass-based pore-forming agent and form pores;

[0012] (3) Spray water for humidification, and seal to balance the moisture after humidification to produce an air purification material.

[0013] After step (1) granulation, the product particles are sized in the range of 0.5-6 mm and sieved using standard sieves of different mesh sizes according to needs.

[0014] Preferably, the components of the air purification material are: in mass percentage, 20-80% porous carrier; 5-50% active ingredient, 0.5-5% binder, 1-10% biomass-based pore former, and 5-20% water; 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% of activated alumina and 5-30% of activated carbon in terms of mass percentage in the air purification material, with a total content of 25-70%.

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

[0017] Preferably, the biomass-based pore-forming agent is wood chips or cotton fibers. Cotton fibers are uniform filaments with a diameter of about 20 μm, and cellulose accounts for more than 90% of their composition. Cellulose easily decomposes in the range of 300-400°C and begins to carbonize above 400°C, easily forming uniform pores. Sawdust particles are around 200 mesh and have a diameter of nearly 80 μm. In addition to cellulose, their composition also contains 20-30% lignin. The decomposition temperature of lignin is between 300-500°C, and carbonization only begins above 500°C. A small amount of residual lignin can support the pores and prevent large pores from collapsing.

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

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

[0020] Preferably, the temperature of the high-temperature anoxic calcination treatment is 400±100° C. and the time is 3±1 h.

[0021] The air purification material prepared by the above method is used to remove alkaline pollutants in the air.

[0022] The penetration test results show that its ammonia adsorption and decomposition capacity is significantly improved. The mechanism is that the high-temperature anoxic calcination process carbonizes the wood chips in the formula, releasing pores, allowing the active ingredients inside and outside the particles to react with alkaline pollutants to play a role. Ammonia is adsorbed into the micropores of the air purification material. The micropores contain water, and the ammonia dissolves in water to form ammonia water (NH3·H2O), which undergoes weak hydrolysis to generate hydroxide ions (OH - ) and ammonium ions (NH4+ Zinc chloride (ZnCl2) reacts with ammonia to form zinc hydroxide (Zn(OH)2) precipitate and ammonium chloride (NH4Cl). Zinc hydroxide reacts with ammonia to form tetraammine zinc 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 to form tetraamminecopper complex ion [Cu(NH3)4]. 2+ Magnesium chloride (MgCl2) reacts with ammonia water 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: The biomass-based pore-forming agent decomposes at high temperature to form through micropores, which increases the diffusion rate of ammonia in the air purification material, improves the efficiency of ammonia adsorption and decomposition and the processing capacity; the sodium carboxymethyl cellulose binder forms a three-dimensional network skeleton structure during low-temperature calcination, ensuring the structural strength of the air purification material.

[0025] (2) Performance advantages: high processing capacity. Referring to MT / T 1067-2008, the method for determining the penetration capacity and penetration time of hydrogen sulfide adsorbed by activated carbon, the air purification material prepared by the present invention has an ammonia processing capacity exceeding 10% of its own mass, which is more than three 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 direct ablation by a butane blowtorch for 30 seconds, and the material has no open flame, no smoldering, and no smoke release. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a physical photo of the air purification material of Example 5 of the present invention.

[0027] Figure 2 This is a blowtorch burning fire resistance test diagram of the air purification material of Example 5 of the present invention; the upper figure is a state diagram during burning, and the lower figure is a state diagram after the fire is turned off. DETAILED DESCRIPTION

[0028] The present invention will be described in further detail below with reference to specific examples, but the embodiments of the present invention are not limited thereto. For process parameters not particularly noted, conventional techniques may be used.

[0029] The butane blowtorch used in the present invention is Explorer brand TXZ-QTQTQT model, and the flame temperature is about 900-1300°C.

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

[0031] Example 1

[0032] Air purification material preparation: according to the mass percentage of active alumina 50%, activated carbon 20%, sawdust 1% powder. Zinc chloride and carboxymethyl cellulose sodium are dissolved in water to form a zinc chloride and carboxymethyl cellulose sodium aqueous solution, and the prepared powder is mixed with the aqueous solution. The content of zinc chloride is controlled at 10%, and the content of carboxymethyl cellulose sodium is controlled at 0.5%. Granulation is performed using a granulator, and particles with a particle size of 10-20 mesh are sieved out using a standard sieve. The sieved particles are dried at 130°C until the weight is constant, and then treated by oxygen-free calcination at 400°C for 3 hours. After calcination, the particles are sprayed with water for humidification and balance, and the water content is controlled at 18.5%.

[0033] Air purification material performance test: refer to the method for measuring the breakthrough capacity and breakthrough time of activated carbon for adsorbing hydrogen sulfide in MT / T 1067-2008, replace hydrogen sulfide with ammonia, and test at room temperature. The total flow of ammonia-air mixed gas is 1500 mL / min, the ammonia concentration is 10000 ppm, and the test is stopped when the ammonia concentration at the tail end of the test tube reaches 50 ppm. The removal efficiency is always ≥99.5%, and the breakthrough time is recorded as 594 min. The ammonia breakthrough capacity of the air purification material prepared in the above example is measured to be 5.2%. The air purification material prepared in the above example is subjected to fire resistance test, and the air purification material is directly burned by butane torch flame for 30 seconds. After leaving the torch flame, the air purification material is free of fire and smoke.

[0034] The breakthrough capacity of ammonia is:

[0035]

[0036] In the formula:

[0037] C - the breakthrough capacity of ammonia, in grams per gram (g / g);

[0038] C Q - the volume percentage of ammonia in the test gas, in percentage (%);

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

[0040] T - the total time of the breakthrough test, in minutes (min);

[0041] 17 - the molar mass of ammonia, in grams per mole (g / mol);

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

[0043] m G—Mass of the penetration test sample in grams (g).

[0044] Referring to the air purification material preparation method of Example 1, different air purification materials were prepared by adjusting the proportions of the components. 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] With reference to the performance test conditions of the air purification material in Example 1, the air purification materials prepared in each example in the table were tested. The test results are shown in Table 2 below.

[0051] Table 2

[0052]

[0053]

[0054] Comparative Example 1

[0055] Compared with Example 5, no oxygen-deficient calcination treatment at 400°C was performed.

[0056] Preparation of air purification material: Prepare powder according to the mass percentage of activated alumina (40%), activated carbon (20%), and sawdust (8%). Dissolve zinc chloride and sodium carboxymethylcellulose in water to prepare a zinc chloride and sodium carboxymethylcellulose aqueous solution. Thoroughly mix the prepared powder and aqueous solution to control the zinc chloride content to 20% and the sodium carboxymethylcellulose content to 2%. Granulate the mixture using a granulator, sieve using a standard sieve, and dry the sieved granules at 130°C to a moisture content of 10%.

[0057] Air purification material performance test: Referring to MT / T 1067-2008, the method for determining the penetration capacity and penetration time of hydrogen sulfide adsorbed on activated carbon was used. The hydrogen sulfide was replaced with ammonia and the test was conducted at room temperature. The total flow rate of the ammonia-air mixture was 1500mL / min, and the ammonia concentration at the air inlet end of the penetration test tube was 10000ppm. The test was stopped when the ammonia concentration at the tail end of the test tube reached 50ppm. The removal efficiency was always ≥99.5%, and the penetration time was recorded as 408min. The ammonia penetration capacity of the air purification material prepared in the above embodiment was measured to be 3.2%. The air purification material prepared in the above embodiment was subjected to a fire resistance test. The air purification material was directly burned with a butane blowtorch flame for 30 seconds. After leaving the blowtorch flame, the air purification material was fireless and smokeless.

[0058] Comparative Example 2

[0059] Compared with Example 5, no pore-forming component, wood chips, was added.

[0060] Preparation of air purification material: Prepare powders according to the mass percentage of activated alumina (40%) and activated carbon (20%). Dissolve zinc chloride and sodium carboxymethyl cellulose in water to create an aqueous solution of zinc chloride and sodium carboxymethyl cellulose. Thoroughly mix the prepared powders with the aqueous solution, controlling the zinc chloride content to 20% and the sodium carboxymethyl cellulose content to 2%. Granulate the mixture using a granulator and sieve using a standard sieve. Dry the sieved granules at 130°C to constant weight and calcine them in the absence of oxygen at 400°C for 3 hours. After calcination, spray the granules with water to humidify and balance them, controlling the moisture content to 18%.

[0061] Air purification material performance test: Referring to MT / T 1067-2008, the method for determining the penetration capacity and penetration time of hydrogen sulfide adsorbed on activated carbon was used. Hydrogen sulfide was replaced with ammonia and the test was conducted at room temperature. The total flow rate of the ammonia-air mixture was 1500 mL / min, and the ammonia concentration at the air inlet end of the penetration test tube was 10,000 ppm. The test was stopped when the ammonia concentration at the tail end of the test tube reached 50 ppm. The removal efficiency was always ≥99.5%, and the penetration time was recorded as 443 min. The ammonia penetration capacity of the air purification material prepared in the above embodiment was measured to be 3.6%. The air purification material prepared in the above embodiment was subjected to a fire resistance test. The air purification material was directly burned with a butane blowtorch flame for 30 seconds. After leaving the blowtorch flame, the air purification material was free of fire and smoke.

[0062] Comparative Example 3

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

[0064] Preparation of air purification material: Prepare a powder with a mass percentage of 60% activated alumina and 8% sawdust. Dissolve zinc chloride and sodium carboxymethylcellulose in water to create an aqueous solution of zinc chloride and sodium carboxymethylcellulose. Thoroughly mix the prepared powder and aqueous solution, controlling the zinc chloride content to 20% and the sodium carboxymethylcellulose content to 2%. Granulate the material using a granulator and sieve using a standard sieve. Dry the sieved particles at 130°C to constant weight and then calcine them in the absence of oxygen at 400°C for 3 hours. After calcination, spray the particles with water to humidify and balance them, controlling the moisture content to 10%.

[0065] Air purification material performance test: Referring to MT / T 1067-2008, the method for determining the penetration capacity and penetration time of hydrogen sulfide adsorbed on activated carbon was used. Hydrogen sulfide was replaced with ammonia and the test was conducted at room temperature. The total flow rate of the ammonia-air mixture was 1500 mL / min, and the ammonia concentration at the air inlet end of the penetration test tube was 10,000 ppm. The test was stopped when the ammonia concentration at the tail end of the test tube reached 50 ppm. The removal efficiency was always ≥99.5%, and the penetration time was recorded as 592 min. The ammonia penetration capacity of the air purification material prepared in the above embodiment was measured to be 4.5%. The air purification material prepared in the above embodiment was subjected to a fire resistance test. The air purification material was directly burned with a butane blowtorch flame for 30 seconds. After leaving the blowtorch flame, the air purification material was free of fire and smoke.

[0066] Comparative Example 4

[0067] Commercially available activated carbon impregnated with 5% phosphoric acid was purchased and its ammonia penetration capacity and fire resistance were tested.

[0068] Referring to MT / T 1067-2008, Determination of the Breakthrough Capacity and Breakthrough Time of Hydrogen Sulfide Adsorbed on Activated Carbon, the hydrogen sulfide was replaced with ammonia. Testing was conducted at room temperature with a total flow rate of 1500 mL / min of the ammonia-air mixture, an initial ammonia concentration of 10,000 ppm, and an ammonia concentration of 50 ppm at the end of the test. The removal efficiency was consistently ≥99.5%, and the breakthrough time was recorded as 371 minutes. The ammonia breakthrough capacity of commercially available activated carbon impregnated with 5% phosphoric acid was measured to be 3.7%. A fire resistance test was conducted on the commercially available activated carbon impregnated with 5% phosphoric acid using a butane blowtorch flame for 30 seconds. After the blowtorch flame was removed, the commercially available activated carbon impregnated with 5% phosphoric acid continued to burn, releasing smoke.

[0069] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing an air purification material for removing alkaline pollutants in the air, characterized in that: The steps include: (1) adding water to the active ingredient and the binder to form an aqueous solution, then uniformly mixing the solution with the porous carrier and the biomass-based pore-forming agent, granulating, and drying to obtain active granules; or adding water to the binder to form an aqueous solution, then uniformly mixing the solution with the porous carrier, the active ingredient, and the biomass-based pore-forming agent, granulating, and drying to obtain active granules; (2) calcining the active particles at high temperature and in the absence of oxygen to carbonize the biomass-based pore-forming agent and form pores; (3) Spray water for humidification, and seal to balance the moisture after humidification to produce an air purification material.

2. The preparation method according to claim 1, characterized in that The components of the air purification material are: in mass percentage, 20-80% of a porous carrier; 5-50% of an active ingredient; 0.5-5% of a binder; 1-10% of a biomass-based pore-forming agent; and 5-20% of water. The porous carrier includes activated alumina and / or activated carbon; and the active ingredient includes one or more of copper sulfate, zinc chloride, and magnesium chloride.

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

4. The preparation method according to claim 2, characterized in that Calculated by mass percentage in the air purification material, the active ingredients include 0-50% of zinc chloride, 0-50% of copper sulfate and 0-50% of magnesium chloride, with a total content of 10-50%.

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

6. The preparation method according to any one of claims 1 to 4, characterized in that The binder is sodium carboxymethyl cellulose.

7. The preparation method according to any one of claims 1 to 4, characterized in that The components of the air purification material are as follows: in mass percentage, 40-70% of a porous carrier, 10-40% of an active ingredient, 1-5% of a binder, 5-10% of a biomass-based pore-forming agent, and 5-15% of water.

8. The preparation method according to any one of claims 1 to 4, characterized in that The temperature of the high-temperature oxygen-deficient calcination treatment is 400±100° C., and the time is 3±1 h.

9. An air purification material obtained by the method according to any one of claims 1 to 8.

10. Use of the air purification material according to claim 9 in removing alkaline pollutants in the air.

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