Tail gas treatment composite material and preparation method and application thereof

Abstract

This invention discloses a composite material for exhaust gas treatment, its preparation method, and its application. A method for preparing the composite material includes the following steps: mixing agricultural and forestry waste with white-rot fungal inoculum, filtering, and obtaining degraded agricultural and forestry waste; mixing the degraded agricultural and forestry waste with sodium hydroxide solution and soaking; adding CS2 for xanthation treatment; then adding activated carbon and a photocatalyst and stirring; finally adding alkaline salt to obtain a porous material; mixing and culturing the porous material with photosynthetic bacteria inoculum, filtering, and obtaining the exhaust gas treatment composite material. The preparation process of the exhaust gas treatment composite material of this invention is green and environmentally friendly, the material is easily degradable, and cellulose is extracted using a biological treatment method, causing no environmental pollution. Furthermore, cellulose and photosynthetic bacteria themselves are biomass materials that can be degraded.

Description

Technical Field

[0001] This invention relates to the field of waste gas treatment technology, and in particular to a composite material for exhaust gas treatment, its preparation method, and its application. Background Technology

[0002] Straw is the residue left after crops are harvested. Currently, the main ways to utilize straw include direct burning, returning it to the field for increased yield, using it as livestock feed, and energy utilization. However, incomplete direct burning produces large amounts of incomplete combustion products such as carbon monoxide, sulfur dioxide, and nitrogen oxides, polluting the atmosphere. The high temperatures generated by large-scale burning also seriously harm beneficial microorganisms in the soil. Returning straw to the field for increased yield has significant limitations. Unfermented, dry straw buried in farmland does not have sufficient fermentation time, and incompletely decomposed straw not only fails to fertilize the field but also affects crop germination rates. In addition, straw is also used as feed and fuel, but the utilization rate is low. How to effectively utilize straw is an urgent problem to be solved.

[0003] Industrial production processes generate large amounts of exhaust gases containing nitrogen oxides and sulfides. Currently, commonly used industrial exhaust gas treatment methods include wet absorption, solid-state adsorption, electron beam irradiation, biological methods, and catalytic methods. However, these methods often suffer from drawbacks such as high investment, high energy consumption, difficult installation, narrow applicability, high operating costs, and secondary pollution. The most common activated carbon adsorption method can only adsorb exhaust gases and cannot completely treat harmful gases. Furthermore, its adsorption performance and efficiency are unstable for different exhaust gases. In addition, activated carbon exhaust gas treatment devices need to be designed specifically for the actual exhaust outlet before they can be put into use, and activated carbon is brittle and fragile, increasing the cost of device preparation and transportation. Currently available diaphragm-type exhaust gas treatment devices use organic solvents to dissolve the matrix, which cannot be naturally degraded, thus causing secondary pollution. Catalytic methods are currently the mainstream development direction for exhaust gas treatment, but they also have problems such as secondary pollution and the requirement for high reaction temperatures. For example, the optimal operating temperature for selective reduction of NO on Ag / Al2O3 catalyst is 500℃, and the optimal operating temperature for selective reduction of NO on Ba / MgO catalyst is 700℃.

[0004] In summary, there are currently few straw-based products on the market, which limits the processing and utilization of straw. Moreover, current exhaust gas treatments generally suffer from multiple drawbacks, such as high investment, high energy consumption, high operating costs, and secondary pollution. There is a lack of an efficient, stable, and reusable exhaust gas treatment material. Summary of the Invention

[0005] In order to overcome the problem that existing technologies cannot effectively utilize crop straw, one objective of this invention is to provide a waste gas treatment composite material, another objective of this invention is to provide a method for preparing such a waste gas treatment composite material, and a third objective of this invention is to provide an application of such a waste gas treatment composite material.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of this invention provides a method for preparing a waste gas treatment composite material, comprising the following steps:

[0008] 1) Mix agricultural and forestry waste with white rot fungal inoculum, filter, and obtain degraded agricultural and forestry waste;

[0009] 2) The degraded agricultural and forestry waste was mixed with sodium hydroxide solution and soaked; then CS2 was added for xanthation treatment; then activated carbon and photocatalyst were added and stirred; finally, alkaline salt was added to obtain porous material;

[0010] 3) The porous material is mixed with photosynthetic bacteria culture and then filtered to obtain the exhaust gas treatment composite material.

[0011] The preparation mechanism of the exhaust gas treatment composite material of the present invention is as follows:

[0012] 1. Biodegradation and cellulose enrichment

[0013] The present invention first treats agricultural and forestry waste with white-rot fungi, a step that degrades the waste while retaining only the cellulose.

[0014] The white-rot fungi secrete lignin peroxidase (LiP), manganese peroxidase (MnP), and laccase, which are the main functional enzymes involved in the degradation of lignin. The lignin peroxidase (LiP) secreted by the fungi first oxidizes non-phenolic compounds in agricultural and forestry waste tissues, opening aromatic rings and simultaneously breaking the Cα-Cβ bonds in the phenylpropyl structure. At the same time, the white-rot fungi secrete manganese peroxidase (MnP) catalyzes lignin, enhancing the oxidative capacity of lignin peroxidase (LiP). The laccase, also secreted by the fungi, oxidizes the phenol structure, producing free radicals containing phenoxy groups, which promote the cleavage of Cα-Cβ bonds and aromatic groups. The three enzymes work simultaneously to complete the efficient degradation of lignin.

[0015] White-rot fungi secrete various enzymes such as 4-D xylanase, endo-β-1, and β-xylosidase, which decompose plant cell walls (i.e., hemicellulose) and some intercellular tissues (such as plasmodesmata) in agricultural and forestry waste tissues, which are composed of different types of monosaccharides such as pentoses, hexoses, arabinose, mannose, xylose, and galactose. This disrupts the plant cell walls and inter-tissue adhesions in agricultural and forestry waste tissues, releasing cellulose into the outside world.

[0016] 2. Mercerizing treatment

[0017] After biodegradation, plant cellulose tissue is treated with NaOH solution to generate alkali-cellulose intermediates, mainly consisting of unstable alcohol compounds and molecular compounds. These intermediates undergo intense and irreversible swelling, resulting in changes to the fiber lattice, disruption of intermolecular forces, hydrogen bond breakage, and molecular rearrangement under tension. Upon initial contact with the fiber, the alkali penetrates the amorphous region, breaking not only the amorphous areas but also the hydrogen bonds between molecular chains, causing swelling. Simultaneously, the alkali also enters the crystalline region, disrupting its bonding and leading to a transformation of the crystal structure, resulting in irreversible and intense swelling. Due to the influence of NaOH... + The small size and hydration capacity of a Na+ + It can be surrounded by about 66 water molecules to form a hydration layer, Na + As it enters the crystalline region inside the fiber, it can bring in a large amount of water, which then combines with the fiber.

[0018] 3. Yellowing treatment

[0019] Carbon disulfide (CS2) is added to alkali cellulose after mercerizing. CS2 molecules penetrate into the interior of cellulose through the alkaline solution that fills the spaces between cellulose molecules, causing xanthic acid groups to bind to the alkali cellulose molecules and forming sodium cellulose xanthate. This makes the distance between cellulose molecules larger and the structure looser, and the reaction gradually develops from the loose amorphous region of cellulose to the compact morphological region.

[0020] 4. Modification and Regeneration Finishing

[0021] Xanthant cellulose eventually forms a porous structure, adsorbing activated carbon and photocatalysts onto its surface. After drying, new intermolecular forces and hydrogen bonds form between the fiber molecules, ultimately shaping the fiber.

[0022] 5. Microbial attachment

[0023] Due to the mesh-fiber structure of porous materials, and the fact that microorganisms use EPS for self-protection, photosynthetic bacteria can easily be loaded onto the material surface, forming the final porous material-photosynthetic bacteria coupled material.

[0024] Preferably, in this preparation method, in step 1), the content of white-rot fungi in the white-rot fungal solution is 0.01-0.5 g / mL; more preferably, the content of white-rot fungi in the white-rot fungal solution is 0.02-0.2 g / mL.

[0025] In some specific embodiments of the present invention, the agricultural and forestry waste is straw.

[0026] Preferably, in this preparation method, in step 1), the mass-to-volume ratio of agricultural and forestry waste to white rot fungal inoculum is 1g:(5-15)mL; more preferably, the mass-to-volume ratio of agricultural and forestry waste to white rot fungal inoculum is 1g:(8-12)mL.

[0027] Preferably, in this preparation method, in step 1), the mixing time between agricultural and forestry waste and white rot fungus inoculum is 48-72 hours; more preferably, the mixing time between agricultural and forestry waste and white rot fungus inoculum is 54-65 hours; and even more preferably, the mixing time between agricultural and forestry waste and white rot fungus inoculum is 58-62 hours.

[0028] Preferably, in this preparation method, in step 2), the concentration of the sodium hydroxide solution is 15-25 wt%; more preferably, the concentration of the sodium hydroxide solution is 18-22 wt%; even more preferably, the concentration of the sodium hydroxide solution is 20 wt%; within a certain limit, the higher the alkali concentration, the better the sodium hydroxide content. + The more numbers, the better. + As the degree of hydration increases, the degree of fiber swelling increases. This invention uses a sodium hydroxide solution with a mass fraction of 20% to maintain a high swelling efficiency.

[0029] Preferably, in this preparation method, in step 2), the mass ratio of the degraded agricultural and forestry waste to the sodium hydroxide solution is 3:(1-13); more preferably, the mass ratio of the degraded agricultural and forestry waste to the sodium hydroxide solution is 3:(5-10).

[0030] Preferably, in this preparation method, in step 2), the time for mixing the degraded agricultural and forestry waste with the sodium hydroxide solution is 3-5 hours; more preferably, the time for mixing the degraded agricultural and forestry waste with the sodium hydroxide solution is 3.5-4.5 hours.

[0031] Preferably, in this preparation method, in step 2), the mass ratio of degraded agricultural and forestry waste to CS2 is 1:(0.5-1.5); more preferably, the mass ratio of degraded agricultural and forestry waste to CS2 is 1:(0.8-1.2).

[0032] Preferably, in this preparation method, the xanthanization treatment time in step 2) is 1.5-2.5h; more preferably, the xanthanization treatment time is 1.8-2.2h.

[0033] Preferably, in this preparation method, in step 2), the mass ratio of degraded agricultural and forestry waste to activated carbon is 1:(0.03-0.5); more preferably, the mass ratio of degraded agricultural and forestry waste to activated carbon is 1:(0.1-0.5); and even more preferably, the mass ratio of degraded agricultural and forestry waste to activated carbon is 1:(0.2-0.5).

[0034] Preferably, in this preparation method, in step 2), the photocatalyst is a titanium dioxide photocatalyst; in some specific embodiments of the present invention, the photocatalyst is manganese-doped titanium dioxide (manganese-titanium dioxide), and the manganese-doped titanium dioxide can be commercially available or self-made; more preferably, the molar mass ratio of titanium to manganese in the manganese-doped titanium dioxide is (25-30):1.

[0035] In some specific embodiments of the present invention, manganese-doped titanium dioxide is prepared by a self-made method, the specific preparation method including the following steps:

[0036] The titanium source was dissolved in a solvent, and an acidic solution was added to obtain solution A; the manganese salt was dissolved in a solvent to obtain solution B; solutions A and B were mixed, stirred, aged, and dried to obtain a solid powder; the solid powder was calcined to obtain manganese-titanium dioxide.

[0037] Preferably, in the method for preparing manganese-doped titanium dioxide, the acidic solution can be one or more of hydrochloric acid, sulfuric acid, nitric acid, and acetic acid; the solvent can be selected from alcohols and / or water.

[0038] Preferably, in the method for preparing manganese-doped titanium dioxide, the calcination temperature is 400-500℃ and the calcination time is 3-5h.

[0039] Preferably, in this preparation method, in step 2), the mass ratio of degraded agricultural and forestry waste to photocatalyst is (40-60):1; more preferably, the mass ratio of degraded agricultural and forestry waste to photocatalyst is (45-55):1.

[0040] Preferably, in this preparation method, the stirring time in step 2) is 36-60 h; more preferably, the stirring time is 42-54 h; and even more preferably, the stirring time is 46-50 h.

[0041] Preferably, in this preparation method, in step 2), the alkaline salt is at least one of sodium dodecyl phosphate and sodium phosphate. Sodium dodecyl phosphate and / or sodium phosphate will undergo vigorous hydrolysis, causing the solution to become alkaline, which further promotes the activation of cellulose and causes it to generate more porous structures. The hydrolysis of sodium dodecyl phosphate and sodium phosphate is more vigorous than that of other salts. Under the same pH conditions, less amount is required, and the porosity of the final porous material is further increased.

[0042] Preferably, in this preparation method, in step 2), the mass ratio of the degraded agricultural and forestry waste to the alkaline salt is (20-60):1.

[0043] Preferably, in this preparation method, in step 2), after adding the alkaline salt, the mixture is heated to a temperature of 60-70°C.

[0044] Preferably, in this preparation method, in step 3), the photosynthetic bacteria content in the photosynthetic bacteria solution is 5 × 10⁻⁶. 6 -5×10 10 cfu / mL; more preferably, the photosynthetic bacteria content in the photosynthetic bacteria culture is 5 × 10⁻⁶. 7 -5×10 9 cfu / mL; further preferably, the photosynthetic bacteria content in the photosynthetic bacteria culture is 1×10⁻⁶. 8 -1×10 9 cfu / mL.

[0045] Preferably, in this preparation method, in step 3), the mass-to-volume ratio of porous material to photosynthetic bacteria solution is 1g:(20-80)mL; more preferably, the mass-to-volume ratio of porous material to photosynthetic bacteria solution is 1g:(40-60)mL.

[0046] Preferably, in this preparation method, in step 3), the time for mixing and culturing the porous material with the photosynthetic bacteria solution is 36-60 h; more preferably, the time for mixing and culturing the porous material with the photosynthetic bacteria solution is 42-54 h; even more preferably, the time for mixing and culturing the porous material with the photosynthetic bacteria solution is 46-50 h.

[0047] Preferably, in this preparation method, in step 3), the porous material and photosynthetic bacteria culture are mixed and cultured under light conditions. During the culture process, aeration can be carried out as needed. The purpose of aeration is to provide appropriate oxygen. Those skilled in the art can select the aeration amount according to the actual growth of the bacteria.

[0048] A second aspect of the present invention provides an exhaust gas treatment composite material prepared by the above-described preparation method.

[0049] When waste gas rich in nitric oxide, volatile tar, and other harmful gases and small particulate solids enters a porous treatment material, the cellulose material, which is both hydrophilic and oleophilic in air, retains the volatile tar and its components within the pores, maintaining a certain degree of hydrophilicity and oleophilicity on a macroscopic scale. Simultaneously, the material retains a certain amount of bound water and free water. The hydroxyl groups also ensure that while the gas system is compressed within the pores, the tar does not adhere to the cellulose fibers, thus not affecting the chemical structure and physical properties of the surface catalyst. Furthermore, due to the obstruction of the fibers in the nanoscale state, the velocity of gas molecules such as nitric oxide decreases rapidly as they pass through the material, resulting in a higher molecular concentration upon contact with activated carbon. This makes it difficult for the molecules to directly penetrate the activated carbon layer. The mass transfer process of capturing and adsorbing nitric oxide gas by the activated carbon encapsulated in the material is faster, leading to a more rapid attainment of adsorption saturation equilibrium and a shorter saturation time.

[0050] The third aspect of the present invention provides a method for regenerating exhaust gas treatment composite materials, comprising the following steps: immersing the exhaust gas treatment composite material after exhaust gas treatment in an alkaline solution, and then placing it under light conditions to achieve regeneration of the exhaust gas composite material.

[0051] When the catalytic cycle of the material reaches its end, the material is removed and immersed in an alkaline solution to neutralize the nitric acid produced by catalytic oxidation: H₂ + +HO - →H2O. Simultaneously, the hydroxyl groups on the cellulose nanofibers, which have nanoscale diameters, exhibit oleophobicity in materials impregnated with alkaline solutions. With more hydroxyl groups exposed on the surface, the angle between the liquid surface tension and the liquid-solid interfacial tension increases, causing cellulose to exhibit oleophobicity underwater. This helps to remove oily organic materials (such as tar) adhering to the cellulose surface and maintain its cleanliness. Furthermore, materials with cellulose as the main framework can withstand greater tensile stress, enabling the separation of oil-water mixtures and emulsions under conventional washing and stretching conditions with high separation efficiency.

[0052] After rinsing, the material can be placed in sunlight (or other conditions with ultraviolet light and ventilation) to accelerate the electron reset of the photocatalyst (TiO2) and the oxidation of residual nitric oxide in the activated carbon, as well as to remove excess water from the porous material and maintain the permeability of the pores. The restored material can then proceed to the next cycle of catalytic treatment.

[0053] The fourth aspect of this invention provides the application of the exhaust gas treatment composite material prepared by the above preparation method in the preparation of desulfurization and / or denitrification catalysts.

[0054] When excited by light, the photocatalyst attached to nanoscale cellulose chains undergoes photocatalytic oxidation to remove NO gas molecules absorbed by activated carbon. Under natural light, the enhanced refraction and scattering of light due to the porous structure between the fibers allows photons to enter the material. Simultaneously, the integration of the fiber structure with the TiO2 crystals compensates for the influence of lattice defects, crystal phase structure, and grain size of the TiO2 crystals themselves, resulting in a material with high specific surface area, crystallinity, and stability. This leads to good adsorption performance, high specific surface area, and high photocatalytic activity, and also enhances the absorption of photons by TiO2 in the visible light range, thus improving the photocatalytic oxidation activity of the catalyst. Upon photon excitation, electrons from the valence band transition to the conduction band, leaving oxygen vacancies in situ. Electrons are released directly or through hydroxyl groups on the cellulose chains into these vacancies: TiO2 + hv → e - CB+h + vB;

[0055] The released electrons will oxidize the oxygen in the pore space into superoxide radicals: e - +O2→O2 - ;

[0056] Bound water or ionized hydroxide ions in the pores are oxidized into hydroxyl radicals: h + vB + H₂O → HO· + H + h + vB+HO - →HO·;

[0057] Superoxide radicals and some hydroxyl radicals react with nitric oxide released into the pores of activated carbon, oxidizing and removing the nitric oxide. Superoxide radicals directly react with nitric oxide to form nitrate ions: ·O2 - +NO→NO3 - ;

[0058] Nitric oxide in the material reacts with water molecules to form nitrogen tetroxide due to concentration and catalysis, and then reacts with water molecules to form nitrite and nitrous acid, providing hydroxide ions for the previous oxidation step: 2NO→N2O4

[0059] N₂O₄ + H₂O → NO₂ - +HO - +HNO2

[0060] The oxidized hydroxyl radicals react with nitric oxide, incompletely oxidized nitrous acid, and nitrite, respectively, ultimately oxidizing them to nitrate: HO· + NO → HNO2, HNO2 + HO· → NO2 - +H2O, NO2 - +HO·→HNO3;

[0061] Electrons and vacancies recombine at the end of a redox reaction: e - +h + vB→heat;

[0062] In addition, during this process, photosynthetic bacteria secrete more EPS, which protects them from oxidation and detachment due to physical factors such as airflow. The complex pores of the material structure also provide a relatively stable survival environment for microorganisms, which is conducive to the formation of a biofilm microenvironment.

[0063] Under anaerobic conditions under light, photosynthetic bacteria primarily engage in photophosphorylation. Through substrate and photophosphorylation, they generate energy and rapidly form chromophores. Photosynthetic pigments absorb light energy and transfer it to the photosynthetic center, where they are excited and release high-energy electrons, synergistically catalyzing NO and other substances in the waste gas. During this catalytic process, photosynthetic bacteria undergo heterotrophic metabolism via glycolysis (EMP) and the tricarboxylic acid cycle (TCA), completing electron transfer and providing themselves with the energy needed for growth and reproduction.

[0064] The beneficial effects of this invention are:

[0065] The preparation process of the exhaust gas treatment composite material of this invention is green and environmentally friendly, and the material is easily degradable. Cellulose is extracted using a biological treatment method, which is pollution-free to the environment. Furthermore, cellulose and photosynthetic bacteria themselves are biomass materials that can be degraded after multiple uses.

[0066] The exhaust gas treatment composite material prepared by this invention is simple to install and has a wide range of applications. Due to its high deformability, the product can be shaped into the required form after stress and can be installed at the end of various exhaust ports in various factories.

[0067] The exhaust gas treatment composite material prepared by this invention exhibits comprehensive and effective absorption of exhaust gases. In addition to inorganic exhaust gases, it also demonstrates strong adsorption capacity for organic waste gases. Besides the adsorption effect brought about by its porous structure, the various functional groups on its surface exhibit oil-absorbing properties in the air, enabling it to absorb approximately 20-30 times its own weight in organic waste gases. Furthermore, under the combined action of photocatalysts and microorganisms, it can convert harmful components in the exhaust gas, such as nitrogen oxides and sulfur oxides, into non-toxic substances, making it more environmentally friendly.

[0068] The exhaust gas treatment composite material prepared by this invention has a long service life and low production cost. The product has good deformation properties, high elasticity, and is detachable. Microorganisms attached to the material can be reused after being soaked in a culture stock solution after a certain period of operation, further extending the product's service life. The soaking operation is convenient, the microbial growth rate is fast, and the cost is low; the entire process is quick and inexpensive. Detailed Implementation

[0069] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0070] The manganese-titanium dioxide used in the embodiments of this invention is prepared by the following method:

[0071] 10g of butyl phthalate was dissolved in 20mL of anhydrous ethanol, and 3 drops of hydrochloric acid and 2mL of acetic acid were added dropwise. The mixture was stirred for 15min and labeled as solution A. 0.13g of manganese chloride was dissolved in 30mL of a mixture of ethanol and water (volume ratio 5:1) and stirred for 15min. This solution was labeled as solution B. Solution B was added dropwise to solution A (while stirring). After the addition was complete, the mixture was stirred for 2h and then aged for 4h. The resulting product was dried at 100℃ for 8h to remove moisture, yielding a solid powder. This powder was then calcined in a muffle furnace at 450℃ for 4h to obtain manganese-titanium dioxide.

[0072] The method for preparing the homogenate of white-rot fungi used in this embodiment of the invention is as follows:

[0073] The activated fungal strain was transferred into PDA liquid medium and cultured for 10 days. The cultured wet mycelium was then mixed with sterile water at a ratio of 1g:20mL, shaken and crushed to obtain a fungal homogenate.

[0074] Example 1

[0075] This embodiment provides a method for preparing a composite material for exhaust gas treatment, including the following steps:

[0076] (1) The straw is crushed and passed through an 80-mesh sieve. 1g of the crushed straw is mixed with 10mL of white rot fungus inoculum and treated at 35℃ for 60h to obtain the treated straw slurry. The straw slurry is centrifuged at 3000rpm for 5min, washed 3 to 4 times, and dried at 80℃ for 48h to obtain the degraded straw.

[0077] (2) Take 2g of degraded straw, add 5g of sodium hydroxide solution with a mass fraction of 20wt%, soak for 4 hours, add 2g of CS2, and xanthate at 25℃ for 2 hours. Then add 0.5g of activated carbon powder and 0.04g of manganese-titanium dioxide to form a slurry. Stir for 2 days at 25℃ and normal pressure. Add 0.05g of Na3PO4·12H2O powder and mix. Heat and regenerate at 65℃. Then soak in warm water to dissolve Na3PO4·12H2O particles.

[0078] (3) First, soak the material processed in step (2) in an ethanol solution for 2 days to remove water chemically and prevent membrane shrinkage. Then take it out and dry it for 1 day to remove water physically, forming a dry, reusable porous material.

[0079] (4) After forming the porous material, place it in a photosynthetic bacteria nutrient solution (concentration of 5×10⁻⁶) at a temperature of 31℃, pH=8 and light intensity of 4504 LUX. 8 In a solution of cfu / mL, aeration was performed every 24 hours at a rate of 500 cm³ / mL. 3 The porous material was aerated at 0.25 L / min for 30 min. Due to the mesh-like fibrous structure of the porous material, photosynthetic bacteria easily adhered to its surface. After 48 hours of treatment, a 1 cm sample was cut. 3 The material was chopped, shaken, dissolved in sterile water, serially diluted, and inoculated onto culture media to determine the bacterial count as 9.1 × 10⁻⁶. 9 cfu / g, forming the final porous material-photosynthetic bacteria coupling material, i.e. exhaust gas treatment composite material.

[0080] The exhaust gas treatment composite material prepared above was used in an exhaust gas treatment experiment. The specific test procedure is as follows:

[0081] Two indoor coal-fired chimneys were used. The coal used in the test was three meters high, wider at the bottom and narrower at the top, with a diameter of 20 cm at the bottom and 16 cm at the top. Continuous combustion and ventilation were maintained during the test. The exhaust gas was measured at each measurement time point. An equal amount of coal was burned. The experimental material was 0.02 cubic meters, and the coal consumption was 10 kg. The experimental group was equipped with the exhaust gas treatment composite material prepared above, while the control group was not equipped with the exhaust gas treatment composite material. The concentrations of nitrogen oxides and sulfides in the exhaust gas inside the coal-fired chimneys were measured at different time points. The test results are shown in Tables 1 and 2 below.

[0082] Table 1. Results of Nitrogen Oxide Content Test

[0083] Measurement time h control group experimental group 3 <![CDATA[40mg / m 3 ]]> <![CDATA[18mg / m 3 <!-- 6 -->]]> 6 <![CDATA[46mg / m 3 ]]> <![CDATA[18mg / m 3 ]]> 9 <![CDATA[69mg / m 3 ]]> <![CDATA[19mg / m 3 ]]> 12 <![CDATA[72mg / m 3 ]]> <![CDATA[20mg / m 3 ]]> 15 <![CDATA[68mg / m 3 ]]> <![CDATA[20mg / m 3 ]]> 18 <![CDATA[57mg / m 3 ]]> <![CDATA[26mg / m 3 ]]> 21 <![CDATA[55mg / m 3 ]]> <![CDATA[35mg / m 3 ]]>

[0084] Table 2. Results of sulfide content test

[0085] Measurement time h control group experimental group 3 <![CDATA[80mg / m 3 ]]> <![CDATA[25mg / m 3 ]]> 6 <![CDATA[83mg / m 3 ]]> <![CDATA[26mg / m 3 ]]> 9 <![CDATA[92mg / m 3 ]]> <![CDATA[26mg / m 3 ]]> 12 <![CDATA[100mg / m 3 ]]> <![CDATA[27mg / m 3 ]]> 15 <![CDATA[108mg / m 3 ]]> <![CDATA[28mg / m 3 ]]> 18 <![CDATA[99mg / m 3 ]]> <![CDATA[25mg / m 3 ]]> 21 <![CDATA[90mg / m 3 ]]> <![CDATA[25mg / m 3 ]]>

[0086] Content determination shows that the exhaust gas treatment composite material of this embodiment has a significant absorption and fixation effect on nitrogen oxides and sulfur oxides in exhaust gas, and has a significant effect on pollution-free emissions.

[0087] Example 2

[0088] Take 6g of straw treated in step (1) of Example 1, add different masses of sodium hydroxide solution with a mass fraction of 20%, and test the expansion volume ratio of the porous material. Use the wax coating and water drainage method. The specific process is as follows: coat the surface with a thin layer of wax, then insert a thin stick into the water and observe that the volume of water discharged is approximately the same as the measured volume. The results are shown in Table 3 below.

[0089] Table 3

[0090] Added amount Expansion volume ratio 2g 10％ 6g 16％ 9g 21％ 12g 53％ 15g 87％ 20g 68％ 25g 42％

[0091] Note: Expansion volume ratio = (Volume after expansion - Volume before expansion) / Volume before expansion

[0092] As shown in the table above, the straw volume expansion ratio is greatest when the mass ratio of straw to 20wt% sodium hydroxide solution is 2:5.

[0093] Example 3

[0094] Take 6g of straw treated in step (1) of Example 1, change the amount of activated carbon powder added, and keep the other steps the same as in Example 1. Measure the sulfur dioxide content in the exhaust gas after 3 hours. The measurement results are shown in Table 4 below.

[0095] Table 4

[0096] Activated carbon powder addition amount sulfur dioxide content 0.2g <![CDATA[79mg / m 3 ]]> 0.5g <![CDATA[53mg / m 3 ]]> 1g <![CDATA[39mg / m 3 ]]> 1.5g <![CDATA[24mg / m 3 ]]> 2g <![CDATA[25mg / m 3 ]]> 2.5g <![CDATA[24mg / m 3 ]]> 3g <![CDATA[26mg / m 3 ]]>

[0097] As shown in the table above, the best sulfur dioxide treatment effect is achieved when 6g of straw is added to 1.5g of activated carbon powder.

[0098] Example 4

[0099] Material recycling test

[0100] The exhaust gas treatment composite material prepared in Example 1 was subjected to multiple exhaust gas treatment experiments. The experimental process was the same as in Example 1. After one exhaust gas treatment experiment (i.e., treatment for 15 hours), multiple repeated experiments were conducted. The test results are shown in Table 5 below.

[0101] Table 5

[0102]

[0103]

[0104] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a composite material for exhaust gas treatment, characterized in that, Includes the following steps: 1) Mix agricultural and forestry waste with white rot fungal inoculum, filter, and obtain degraded agricultural and forestry waste; 2) The degraded agricultural and forestry waste was mixed with sodium hydroxide solution and soaked; then CS2 was added for xanthation treatment; then activated carbon and photocatalyst were added and stirred; finally, alkaline salt was added to obtain porous material; 3) The porous material is mixed with photosynthetic bacteria culture and then filtered to obtain the exhaust gas treatment composite material; The agricultural and forestry waste mentioned is straw; The alkaline salt is at least one of sodium phosphate dodecahydrate and sodium phosphate.

2. The preparation method according to claim 1, characterized in that, In step 1), the content of white rot fungi in the white rot fungal inoculum is 0.01-0.5 g / mL; the mass-volume ratio of agricultural and forestry waste to white rot fungal inoculum is 1 g: (5-15) mL; and the mixing time of agricultural and forestry waste and white rot fungal inoculum is 48-72 h.

3. The preparation method according to claim 1, characterized in that, In step 2), the concentration of the sodium hydroxide solution is 15-25 wt%; the mass ratio of the degraded agricultural and forestry waste to the sodium hydroxide solution is 3:(1-13); and the mixing time of the degraded agricultural and forestry waste and the sodium hydroxide solution is 3-5 h.

4. The preparation method according to claim 1, characterized in that, In step 2), the mass ratio of the degraded agricultural and forestry waste to CS2 is 1:(0.5-1.5); the xanthation treatment time is 1.5-2.5h.

5. The preparation method according to claim 1, characterized in that, In step 2), the mass ratio of the degraded agricultural and forestry waste to activated carbon is 1:(0.03-0.5).

6. The preparation method according to claim 1, characterized in that, In step 2), the mass ratio of the degraded agricultural and forestry waste to the photocatalyst is (40-60):

1.

7. The preparation method according to claim 1, characterized in that, In step 2), the stirring time is 36-60 hours.

8. The preparation method according to claim 1, characterized in that, In step 3), the content of photosynthetic bacteria in the photosynthetic bacterial solution is 5×10 6 -5×10 10 cfu / mL; the mass-volume ratio of the porous material to the photosynthetic bacterial solution is 1 g:(20-80) mL; and the time for mixed culture of the porous material and the photosynthetic bacterial solution is 36-60 h.

9. A composite material for exhaust gas treatment, characterized in that, The exhaust gas treatment composite material is prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the exhaust gas treatment composite material prepared by the preparation method according to any one of claims 1 to 8 in the preparation of desulfurization and / or denitrification catalysts.

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