A composite coating for in-situ biological regeneration of adsorption materials and a method for preparing the same

Abstract

The present application relates to waste gas treatment technical field, specifically, it is a kind of composite coating for in-situ biological regeneration of adsorption material and its preparation method.It includes calcium hydroxide, activated carbon, zeolite, peat, ethylene-vinyl acetate copolymer, hydroxypropyl methyl cellulose, sodium citrate and deionized water;By pre-dispersing ethylene-vinyl acetate copolymer and hydroxypropyl methyl cellulose under certain conditions to form three-dimensional network colloid, and introducing pre-activated sodium citrate, it can generate stable organic-inorganic complex structure with peat humic acid and calcium hydroxide in situ during solidification process;Not only as the reinforcement framework of coating, improve the structural stability, water resistance and adhesion to substrate of coating in humid waste gas environment, effectively prevent coating peeling and nutrient component loss;So as to guarantee the sustained, efficient in-situ biological regeneration function of coating.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste gas treatment, in particular to a composite coating for in-situ biological regeneration of adsorption materials and a preparation method thereof. BACKGROUND

[0002] At present, in the field of waste gas treatment, conventional adsorption materials (such as activated carbon) can efficiently capture pollutants, but they are prone to saturation during operation and need to be frequently replaced or regenerated offline, and there is a risk of combustion and secondary pollution. In order to improve the sustained use efficiency of the material, some studies attempt to combine the adsorbent with a biologically active component to form a composite coating material with biological regeneration potential, in the hope of achieving biological degradation of pollutants while adsorbing, thereby prolonging the service life of the material and reducing the operating burden.

[0003] In the prior art, a physical mixing or simple coating method is often used to combine microbial carriers (such as bamboo charcoal and porous ceramic) with adsorbents to achieve adsorption and partial biological decomposition of pollutants; but for low-concentration and fluctuating waste gas, due to low mass transfer efficiency of adsorption sites and microorganisms, unstable supply of microbial nutrients, weak bonding force between the coating and the substrate, and other reasons, the regeneration efficiency is limited, and there are still some deficiencies: for example, the adsorption component and the biologically active layer are prone to separation or uneven distribution, which not only reduces the interface enrichment and degradation synergy efficiency of pollutants, causing incomplete regeneration; at the same time, it affects the structural stability and moisture holding capacity of the coating, and also reduces the long-term survival activity of microorganisms, leading to easy decay of the coating function; thereby reducing the in-situ and continuous biological regeneration capacity and long-term operation reliability of the composite coating.

[0004] Therefore, there is an urgent need for a composite coating for in-situ biological regeneration of adsorption materials and a preparation method thereof. SUMMARY

[0005] The present application aims to provide a composite coating for in-situ biological regeneration of adsorption materials and a preparation method thereof to solve the problems raised in the background art.

[0006] To achieve the above-mentioned purpose, the present application provides a composite coating for in-situ biological regeneration of adsorption materials, which comprises the following raw materials:

[0007] Calcium hydroxide 30-70wt%; activated carbon 10-50wt%; zeolite 5-30wt%; peat 5-25wt%; ethylene-vinyl acetate copolymer (EVA) 3-12wt%; hydroxypropyl methylcellulose (HPMC) 0.1-1wt%; sodium citrate 0.05-0.8wt%; deionized water 1-8wt%; wherein:

[0008] The ethylene-vinyl acetate copolymer and the hydroxypropyl methyl cellulose synergistically form a three-dimensional network bonding framework in deionized water, firmly covering and cross-linking the calcium hydroxide, activated carbon, zeolite and peat to form a stable porous coating structure; the sodium citrate and the humic acid substances in the peat interact with each other, buffer the acid-base balance of the microenvironment, and integrate and stably release the trace elements therein, to provide a persistent and balanced nutrient source for the colonization and metabolic activity of the microbial community; the microporous structure of the activated carbon and zeolite and the abundant mesoporous and macroporous structure of the peat interpenetrate to form a composite network with a gradient pore size distribution, so that small molecule pollutants are enriched in micropores, and macromolecules and biological flora are mainly distributed in mesoporous and macroporous spaces, thereby promoting the efficient interfacial mass transfer of the adsorbed pollutants to adjacent microorganisms.

[0009] Preferably, the zeolite adopts clinoptilolite or mordenite with a particle size of 150-400 mesh, and the clinoptilolite and mordenite have regular pore structures, good ion exchange properties and moderate surface acidity, which are beneficial to the selective adsorption and enrichment of polar odor molecules; the peat adopts herbaceous peat or moss peat after crushing and drying treatment, which has a high humic acid content, a rich fiber structure, a strong water and fertilizer retention capacity, and can effectively maintain the humidity and nutrient reserves of the coating; the ethylene-vinyl acetate copolymer selects a granular or powdered copolymer with a vinyl acetate content of 18-40%.

[0010] Preferably, the amount of calcium hydroxide is 35-45wt%; the amount of activated carbon is 25-35wt%; the amount of zeolite is 10-15wt%; the amount of peat is 10-18wt%; the amount of ethylene-vinyl acetate copolymer is 5-8wt%; the amount of hydroxypropyl methyl cellulose is 0.2-0.6wt%; the amount of sodium citrate is 0.1-0.4wt%; and the amount of deionized water is 2-5wt%.

[0011] In the application, there is a synergistic effect between calcium hydroxide, sodium citrate and humic acid components in peat, and the carboxylate groups in sodium citrate ( ) and the humic acid in peat ( ) and the calcium ions released by calcium hydroxide ( ) form a complex coordination structure, and the reaction formula is: Related complex The process stabilizes the active nutrient components in the peat through complexation on one hand, so that the nutrient components can be released slowly and continuously; on the other hand, the generated complex fills the gaps between the coating particles and further crosslinks the polymer network formed by the ethylene-vinyl acetate copolymer / hydroxypropyl methyl cellulose, thereby enhancing the structural compactness, water resistance and overall stability of the coating, reducing the loss of nutrients and the structural looseness of the coating in a humid environment.

[0012] Secondly, according to the method for preparing the composite coating for in-situ biological regeneration of adsorption materials, the method comprises the following steps: Figure 1

[0013] S1, raw material pretreatment and drying: the activated carbon, zeolite and peat are respectively placed in a crusher for crushing, and then sieved to obtain materials with a particle size of 150-400 mesh; then, the materials are put into a drying device and dried at 80-105°C until the water content of the materials is less than 2%;

[0014] S2, pre-dispersion of the binder and initial mixing of the slurry: the ethylene-vinyl acetate copolymer (EVA) and the hydroxypropyl methyl cellulose (HPMC) are put into a container with stirring and heating functions together with 30-50% of deionized water, and continuously stirred at a speed of 400-500 r / min at a temperature of 50-60°C for 30-40 min until the mixture is completely dissolved and uniformly dispersed to form a transparent and non-granular viscous colloid; then, the pre-activated sodium citrate is added, and the stirring is continued at the same temperature and speed for 15-20 min to make the sodium citrate fully dispersed and uniformly distributed in the colloid to form a slurry matrix with uniform film-forming and bonding properties;

[0015] S3, mixing and homogenization of the functional components: the materials with a water content of less than 2% are sequentially added to the slurry matrix, and the remaining deionized water is added; the stirring is carried out at a speed of 600-800 r / min at room temperature for 40-60 min until a paste-like slurry is formed, which is uniform, stable and has no obvious particle agglomeration; the activated carbon and zeolite as the adsorption skeleton, the peat as the nutrient source and the calcium hydroxide with the functions of adjustment and solidification are fully infiltrated and dispersed in the three-dimensional network structure formed by the ethylene-vinyl acetate copolymer and the hydroxypropyl methyl cellulose to form a composite slurry system with gradient pore characteristics;

[0016] S4, vacuum degassing and consistency regulation: the paste-like slurry is placed in a vacuum degassing device and degassed at a pressure of -0.08 to -0.1 MPa for 10-20 min to eliminate the air bubbles in the slurry, which can improve the compactness and uniformity of the slurry; after the treatment, the viscosity of the slurry is adjusted to 2000-5000 mPa·s, and a homogeneous slurry is obtained;

[0017] ​S5, coating forming and curing: the homogeneous slurry is coated on the surface of the substrate by spraying, dipping or blade coating, the wet coating thickness is 0.5-2.0 mm, then the coated substrate is moved into a curing device with temperature and humidity control function, and is cured at 40-65 DEG C and 50-70% relative humidity for 8-24 h, in the process of curing, the ethylene-vinyl acetate copolymer and the hydroxypropyl methyl cellulose in the slurry form a three-dimensional network bonding framework under the condition that the moisture gradually volatilizes, at the same time, the calcium hydroxide, sodium citrate and humic acid substances in the peat interact to generate stable organic-inorganic compounds, which further fill and strengthen the nodes and pores of the network framework; finally, a composite coating with stable structure, through pores and firm combination with the substrate is formed.

[0018] Further, in the S2, the pre-activation treatment of sodium citrate includes the following steps:

[0019] The sodium citrate, potassium dihydrogen phosphate and microcrystalline cellulose are placed in a planetary ball mill jar, mixed and ground at a speed of 80-150 r / min for 8-12 min at room temperature, then transferred to a stirring container containing an ethanol aqueous solution, stirred at a speed of 180-250 r / min for 6-8 min to make it fully infiltrate and form a uniformly dispersed suspension slurry, and finally, placed and aged in a closed environment for 12-15 min to obtain modified sodium citrate with good dispersity and surface activity.

[0020] Preferably, the amount of potassium dihydrogen phosphate is 6-9% of the total mass of sodium citrate; the amount of microcrystalline cellulose is 0.8-1.2% of the total mass of sodium citrate; the ethanol aqueous solution is prepared by mixing ethanol and deionized water at a volume ratio of 1:3-1:5, and the amount is 1.2-1.8 times the total mass of sodium citrate, and the temperature is 35-40 DEG C.

[0021] Further, in the S4, the slurry viscosity adjustment includes the following cases:

[0022] When the slurry viscosity is too high, a small amount of deionized water is added successively, the amount of each addition is not more than 2% of the total mass of the slurry, and stirring is carried out at a speed of 50-100 r / min for 5-10 min until the viscosity decreases to the target range;

[0023] When the slurry viscosity is too low, the slurry is placed in an environment of 25-35 DEG C and continuously stirred at a speed of 30-50 r / min for 10-40 min, so that the viscosity rises to the target range through water evaporation and system self-thickening.

[0024] Compared with the prior art, the present application has the following advantages:

[0025] 1、The composite coating for in-situ biological regeneration of adsorption materials and its preparation method, by pre-dispersing ethylene-vinyl acetate copolymer and hydroxypropyl methyl cellulose under specific conditions to form a three-dimensional network colloid, and introducing pre-activated sodium citrate, so that it can generate a stable organic-inorganic complex structure with peat humic acid and calcium hydroxide in situ during the curing process; not only as a reinforced framework of the coating, it improves the structural stability, water resistance and adhesion to the substrate of the coating in a humid waste gas environment, effectively preventing coating peeling and nutrient component loss; at the same time, the complex structure can release the essential nutrient elements for microorganisms carried in the peat gently and continuously, providing a stable and balanced microenvironment for long-term colonization and high-activity metabolism of microbial communities, thereby ensuring the sustained and efficient in-situ biological regeneration function of the coating.

[0026] 2、The composite coating for in-situ biological regeneration of adsorption materials and its preparation method, by pre-dispersing ethylene-vinyl acetate copolymer and hydroxypropyl methyl cellulose under specific conditions to form a three-dimensional network colloid, and introducing pre-activated sodium citrate, so that it can generate a stable organic-inorganic complex structure with peat humic acid and calcium hydroxide in situ during the curing process; not only as a reinforced framework of the coating, it improves the structural stability, water resistance and adhesion to the substrate of the coating in a humid waste gas environment, effectively preventing coating peeling and nutrient component loss; at the same time, the complex structure can release the essential nutrient elements for microorganisms carried in the peat gently and continuously, providing a stable and balanced microenvironment for long-term colonization and high-activity metabolism of microbial communities, thereby ensuring the sustained and efficient in-situ biological regeneration function of the coating. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The preparation method flowchart of the composite coating for in-situ biological regeneration of adsorption materials of the present application;

[0028] Figure 2 The coating adhesion retention rate of the present application is shown in the following graph;

[0029] Figure 3 The anti-washing property of the present application is shown in the following graph. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0031] Example 1

[0032] First, 10 parts by weight of activated carbon, 2.5 parts by weight of clinoptilolite (300 mesh), and 3.8 parts by weight of herbaceous peat were crushed and passed through a 200-mesh sieve, and then dried in an oven at 95°C until the water content was less than 2%. Next, a slurry base was prepared: 1.2 parts by weight of ethylene-vinyl acetate copolymer (EVA, vinyl acetate content 28%) and 0.1 parts by weight of hydroxypropyl methylcellulose (HPMC) were added to a container with heating and stirring functions along with 60% of the total amount of deionized water (i.e., 1.0 parts by weight), stirred at 55°C in a water bath at a speed of 450 r / min for 35 min, until a uniform transparent viscous colloid was formed. The sodium citrate was pre-activated: 0.075 parts by weight of sodium citrate was added to 7.5% of its mass of potassium dihydrogen phosphate and 1.0% of microcrystalline cellulose, mixed and ground in a planetary ball mill at a speed of 120 r / min for 10 min; then the mixture was transferred to a stirring container, 1.5 times the mass of an ethanol aqueous solution (ethanol to deionized water in a volume ratio of 1:4) at a temperature of 38°C was added, stirred at a speed of 200 r / min for 7 min, and then sealed and allowed to stand for 13 min to obtain a pre-activated sodium citrate suspension slurry. The slurry was added to the aforementioned EVA / HPMC colloid, and stirring was continued at 55°C and 450 r / min for 18 min. Then, the dried activated carbon, zeolite, peat, and 7.5 parts by weight of calcium hydroxide were sequentially added to the slurry base, and the remaining 0.7 parts by weight of deionized water was added, and the mixture was stirred at a speed of 700 r / min for 50 min at room temperature to obtain a uniform paste slurry. The slurry was placed in a vacuum degassing machine and degassed at -0.09 MPa for 15 min to eliminate internal bubbles. After degassing, the slurry was placed in an environment at 30°C and slowly stirred at a speed of 40 r / min for 25 min to naturally thicken the viscosity to about 3500 mPa·s, and a homogeneous slurry was obtained. Finally, the slurry was coated on the surface of a pre-prepared porous calcium silicate substrate using the dipping method, and the wet coating thickness was controlled to be 1.2 mm. Then, the coated substrate was moved to a curing room and cured at 50°C and a relative humidity of 60% for 16 h to obtain an adsorbent material loaded with a composite coating.

[0033] Example 2

[0034] First, 8.4 parts by weight of activated carbon, 3.0 parts by weight of mordenite (400 mesh), and 3.6 parts by weight of peat moss were ground through a 250-mesh screen and dried at 100°C until the water content was less than 2%. Second, a slurry base was prepared: 1.8 parts by weight of ethylene-vinyl acetate copolymer (EVA, vinyl acetate content 33%) and 0.15 parts by weight of hydroxypropyl methylcellulose (HPMC) were mixed with 0.39 parts by weight of deionized water (50% of the total amount) at 60°C and 400 r / min for 40 min to form a uniform gel. Sodium citrate was pre-activated: 0.06 parts by weight of sodium citrate was ball-milled with 8% of its mass of potassium dihydrogen phosphate and 1.1% of microcrystalline cellulose for 12 min. Then, 1.6 times the mass of 40°C ethanol aqueous solution (ethanol: water = 1:5) was added, stirred at 180 r / min for 8 min, and allowed to stand for 15 min to obtain a modified slurry, which was then added to the gel and stirred for another 15 min. Then, the dried activated carbon, mordenite, peat moss, and 10.5 parts by weight of calcium hydroxide were added in sequence, and the remaining 0.39 parts by weight of deionized water was added, and stirred at 750 r / min for 45 min at room temperature to form a paste-like slurry. The slurry was vacuum degassed at -0.1 MPa for 12 min, then a small amount of deionized water (total amount not more than 2% of the mass of the slurry) was added dropwise, and stirred at 60 r / min to adjust the viscosity of the slurry to about 2800 mPa·s. The homogeneous slurry was uniformly coated on the surface of the porous alumina substrate by spraying, and the wet film thickness was controlled at 0.9 mm. Finally, the sample was placed in a curing device and cured at 45°C and 65% relative humidity for 20 h to obtain the finished product.

[0035] Example 3

[0036] First, 14 parts by weight of activated carbon, 6 parts by weight of clinoptilolite (150 mesh), and 4 parts by weight of herbaceous peat were ground and sieved through a 150-mesh screen, and then dried at 85°C until the water content was less than 2%. Then, a slurry base was prepared by mixing 3.2 parts by weight of ethylene-vinyl acetate copolymer (EVA, vinyl acetate content 22%) with 0.24 parts by weight of hydroxypropyl methylcellulose (HPMC) and 0.52 parts by weight of deionized water (35% of the total amount), and stirring at 50°C and 500 r / min for 30 min. Sodium citrate was pre-activated by mixing 0.04 parts by weight of sodium citrate with 6.5% of the mass of potassium dihydrogen phosphate and 0.9% of microcrystalline cellulose, and ball-milling for 8 min. An aqueous ethanol solution (ethanol:water = 1:3) was added at 1.3 times the mass and 35°C, and stirred at 220 r / min for 6 min, and then allowed to stand for 12 min. The resulting slurry was mixed with the colloid and stirred for another 20 min. Then, the dried activated carbon, zeolite, peat, and 14 parts by weight of calcium hydroxide were added, and the remaining 0.97 parts by weight of deionized water was added, and stirred at 600 r / min for 60 min to obtain a uniform slurry. After vacuum degassing (-0.08 MPa, 20 min), the viscosity was increased to about 4800 mPa·s by stirring at 28°C and 35 r / min for 40 min. The slurry was coated on the surface of the porous ceramic substrate using a doctor blade method, and the wet layer thickness was 1.8 mm. Finally, the composite coating material was prepared by treating it in a curing environment at 60°C and a relative humidity of 55% for 12 h.

[0037] Example 4

[0038] First, 10 parts by weight of activated carbon, 5.6 parts by weight of mordenite (200 mesh), and 3.2 parts by weight of peat moss were crushed to pass through a 180-mesh sieve and dried at 90°C until the water content was less than 2%. Next, a slurry base was prepared: 2.8 parts by weight of ethylene-vinyl acetate copolymer (EVA, vinyl acetate content 40%) was mixed with 0.12 parts by weight of hydroxypropyl methylcellulose (HPMC) and 45% of deionized water (1.485 parts by weight) in total, and stirred at 58°C and 420 r / min for 38 min. Sodium citrate was pre-activated: 0.16 parts by weight of sodium citrate was ball-milled with 9% of potassium dihydrogen phosphate and 1.2% of microcrystalline cellulose by mass for 11 min; 1.8 times the mass of 37°C ethanol aqueous solution (ethanol: water = 1:4.5) was added, stirred at 250 r / min for 7.5 min, and allowed to stand for 14 min to mature; the modified slurry was added to the colloid and stirred for another 16 min. Then, 18 parts by weight of calcium hydroxide was added to the dried activated carbon, zeolite, and peat, and the remaining 1.815 parts by weight of deionized water was added, and stirred at 800 r / min for 40 min to obtain a paste-like slurry. After vacuum degassing (-0.095 MPa, 18 min), the viscosity was adjusted to about 2000 mPa·s by adding a small amount of deionized water and low-speed stirring. The slurry was coated on a porous lightweight aggregate substrate using the dipping method, and the wet coating thickness was 2.0 mm. Finally, the coating was cured at 55°C and 50% relative humidity for 18 h to complete the preparation.

[0039] In order to verify that the composite coating prepared by the embodiment of the present application has good structural stability and long-term biological regeneration performance, the following test examples are used to illustrate the composite coating provided by the embodiment of the present application.

[0040] Test Example

[0041] The purpose of this test group is to explore the influence of different component ratios on the composite coating, and to detect the coating adhesion, anti-washing performance, microbial nutrient slow-release performance, and long-term waste gas removal stability of the composite coating of the present application.

[0042] Test Objective: Test Group A, Test Group B, Test Group C, and Test Group D respectively use the component ratios of the composite coatings provided by Examples 1-4; Control Example uses Control Group A, Control Group B, Control Group C, Control Group D, Control Group E, Control Group F, Control Group G, Control Group H, Control Group I, Control Group J, and Control Group K, wherein:

[0043] Control Group A

[0044] The preparation method of the composite coating and the raw materials and the amount are exactly the same as those in Example 1, the only difference is that the sodium citrate is not pre-activated, but directly uses the commercially available sodium citrate powder without any treatment. Specifically, in step S2, 0.075 parts by weight of sodium citrate powder is directly added to the colloid formed by stirring 1.2 parts by weight of ethylene-vinyl acetate copolymer, 0.1 parts by weight of hydroxypropyl methyl cellulose and 1.0 parts by weight of deionized water at 55°C for 35 min, and the stirring is continued at 55°C and 450 r / min for 18 min.

[0045] Control group B

[0046] The preparation method of the composite coating and the raw material amount are basically the same as those in Example 1, the difference is that sodium citrate is not added in the formula. Specifically, the raw material composition is: activated carbon 10 parts by weight, clinoptilolite (300 mesh) 2.5 parts by weight, herbaceous peat 3.8 parts by weight, calcium hydroxide 7.5 parts by weight, ethylene-vinyl acetate copolymer 1.2 parts by weight, hydroxypropyl methyl cellulose 0.1 parts by weight, deionized water 1.7 parts by weight. During preparation, the pre-activation and addition steps of sodium citrate are not performed, and the dried activated carbon, zeolite, peat and calcium hydroxide are directly added to the colloid prepared by ethylene-vinyl acetate copolymer, hydroxypropyl methyl cellulose and all deionized water (1.7 parts by weight) at 55°C, stirred at room temperature at 700 r / min for 50 min, and the subsequent vacuum degassing, consistency adjustment, coating and curing steps are the same as those in Example 1. Finally, the comparative coating material is prepared.

[0047] Control group C

[0048] The preparation method of the composite coating and the raw material amount are basically the same as those in Example 1, the difference is that ethylene-vinyl acetate copolymer (EVA) is not added in the formula. Specifically, the raw material composition is: activated carbon 10 parts by weight, clinoptilolite (300 mesh) 2.5 parts by weight, herbaceous peat 3.8 parts by weight, calcium hydroxide 7.5 parts by weight, hydroxypropyl methyl cellulose 1.3 parts by weight (i.e. the sum of the original ethylene-vinyl acetate copolymer 1.2 parts by weight and the original hydroxypropyl methyl cellulose 0.1 parts by weight), sodium citrate 0.075 parts by weight, deionized water 1.7 parts by weight. During preparation, 1.3 parts by weight of hydroxypropyl methyl cellulose and 60% of the total amount of deionized water (1.02 parts by weight) are stirred at 55°C and 450 r / min for 35 min to form a colloid, and then the pre-activated sodium citrate suspension slurry (treatment method same as Example 1) is added and stirred for 18 min. The subsequent steps are the same as those in Example 1, and finally the comparative coating material is prepared.

[0049] Control group D

[0050] The preparation method and raw material amount of the composite coating are basically the same as those in Example 2, except that the zeolite used is replaced by a common broken industrial zeolite (200 mesh) without a regular pore structure, ion exchange performance and moderate surface acidity. Specifically, 3.0 parts by weight of the common broken zeolite is used to replace the mordenite in Example 2, and other raw materials (8.4 parts by weight of activated carbon, 3.6 parts by weight of moss peat, 10.5 parts by weight of calcium hydroxide, 1.8 parts by weight of ethylene-vinyl acetate copolymer, 0.15 parts by weight of hydroxypropyl methyl cellulose, 0.06 parts by weight of sodium citrate, 0.78 parts by weight of deionized water) and all preparation steps (including sodium citrate pre-activation, slurry preparation, coating and curing) are consistent with Example 2. A comparative coating material is finally prepared.

[0051] Control group E

[0052] The preparation method and raw material amount of the composite coating are basically the same as those in Example 2, except that the peat used is replaced by low-position peat with high mineralization degree, low humic acid content and poor fiber structure. Specifically, 3.6 parts by weight of the low-position peat is used to replace the moss peat in Example 2, and other raw materials and all preparation steps are consistent with Example 2. A comparative coating material is finally prepared.

[0053] Control group F

[0054] The preparation method and raw material amount of the composite coating are basically the same as those in Example 2, except that the hydroxypropyl methyl cellulose (HPMC) is not added in the formula. Specifically, the raw material composition is: 8.4 parts by weight of activated carbon, 3.0 parts by weight of mordenite (400 mesh), 3.6 parts by weight of moss peat, 10.5 parts by weight of calcium hydroxide, 1.95 parts by weight of ethylene-vinyl acetate copolymer (i.e. the sum of the original ethylene-vinyl acetate copolymer 1.8 parts by weight and the original hydroxypropyl methyl cellulose 0.15 parts by weight), 0.06 parts by weight of sodium citrate, and 0.78 parts by weight of deionized water. During preparation, 1.95 parts by weight of ethylene-vinyl acetate copolymer is stirred with 50% of the total amount of deionized water (0.39 parts by weight) at 60°C and 400 r / min for 40 min to form a colloid, and then the pre-activated sodium citrate suspension slurry is added and stirred for 15 min. The subsequent steps are the same as in Example 2, and a comparative coating material is finally prepared.

[0055] Control group G

[0056] The preparation method of the composite coating is basically the same as that in Example 3, except that the raw material ratio is adjusted to the upper limit. Specifically, the raw material composition is: calcium hydroxide 70 parts by weight, activated carbon 10 parts by weight, zeolite (clinoptilolite, 150 mesh) 5 parts by weight, peat (herbaceous peat) 5 parts by weight, ethylene-vinyl acetate copolymer 3 parts by weight, hydroxypropyl methyl cellulose 0.1 parts by weight, sodium citrate 0.05 parts by weight, and deionized water 6.85 parts by weight. The preparation steps and parameters (such as drying temperature, stirring speed, curing conditions, etc.) are adjusted adaptively (for example, due to the large amount of water, the stirring and curing time is appropriately extended) with reference to Example 3, but the core process (raw material pretreatment, sodium citrate pre-activation, slurry mixing, vacuum defoaming, coating and curing) remains the same, and finally the comparative coating material is prepared.

[0057] Control group H

[0058] The preparation method of the composite coating is basically the same as that in Example 3, except that the raw material ratio is adjusted to the lower limit. Specifically, the raw material composition is: calcium hydroxide 30 parts by weight, activated carbon 50 parts by weight, zeolite (clinoptilolite, 150 mesh) 30 parts by weight, peat (herbaceous peat) 25 parts by weight, ethylene-vinyl acetate copolymer 12 parts by weight, hydroxypropyl methyl cellulose 1 part by weight, sodium citrate 0.8 parts by weight, and deionized water 8 parts by weight. The preparation steps and parameters are adaptively adjusted (for example, due to the high solid content, the water amount and stirring intensity are adjusted) with reference to Example 3, but the core process remains the same, and finally the comparative coating material is prepared.

[0059] Control group I

[0060] The preparation method of the composite coating and the amount of raw materials are basically the same as those in Example 4, except that when the sodium citrate is pre-activated, the amount of potassium dihydrogen phosphate and microcrystalline cellulose used is higher than the specified range of the present application. Specifically, 0.16 parts by weight of sodium citrate is taken, 15% of its mass of potassium dihydrogen phosphate (higher than the range of 6-9%) and 2.0% of its mass of microcrystalline cellulose (higher than the range of 0.8-1.2%) are added, and the subsequent ball milling, ethanol aqueous solution soaking, and standing and curing steps are the same as those in Example 4. The modified slurry obtained is used for subsequent slurry preparation. Other raw materials and preparation steps remain the same as those in Example 4, and finally the comparative coating material is prepared.

[0061] Control group J

[0062] Take bamboo charcoal powder 30 parts by weight, ceramic particles (particle size 3-5 mm) 50 parts by weight, activated sludge concentrate (water content 95%) from sewage treatment plant 20 parts by weight, sodium alginate 5 parts by weight, and 200 parts by weight of deionized water are mixed, stirred at 300 r / min at room temperature for 60 min to form a mixed slurry. The pre-prepared porous ceramic substrate (similar to the substrate of the present application) is immersed in the slurry, soaked for 5 min, then taken out and drained the excess slurry. Subsequently, the impregnated ceramic is immersed in a 5% calcium chloride solution for cross-linking and solidification for 30 min. After solidification, wash with deionized water for 3 times to remove the surface residual calcium chloride and free substances, and finally dry at 40℃ for 12h to obtain the contrast filler with a biological coating on the surface.

[0063] Control group K

[0064] Take coal quality granular activated carbon (200 mesh) 40 parts by weight, diatomite (300 mesh) 15 parts by weight, polyvinyl alcohol (PVA-1788) 8 parts by weight, and 80 parts by weight of deionized water are mixed. The mixture is stirred in a 85℃ water bath at 400 r / min for 120 min until the PVA is completely dissolved, forming a uniform suspension. The suspension is uniformly sprayed on the surface of the pretreated honeycomb ceramic carrier using a spraying device, and the spraying amount is controlled to make the wet film thickness about 1.0 mm. Subsequently, the sprayed carrier is dried in an oven at 80℃ for 4h, and then heat treated at 120℃ for 2h to solidify the coating, obtaining a pure physical adsorption contrast coating material without biological nutrient components.

[0065] Test method: According to the coating adhesion, anti-washing property, microbial nutrient slow-release performance and long-term waste gas removal stability of the composite coating of the present application, tests are carried out respectively, and the specific test methods are as follows:

[0066] Coating adhesion: The grid method is used to evaluate the adhesion firmness of the coating and the porous substrate; the coating sample is placed in a standard environment [temperature (23±2)℃, relative humidity (50±5)%] for more than 24h; a sharp single-edge cutting knife is used to draw a grid-shaped cut on the surface of the coating, with a spacing of 2mm, ensuring that the cut completely penetrates the coating to the substrate; after cleaning the cut, a high-adhesion pressure-sensitive adhesive tape (adhesion force ≥3.0N / 10mm) with a width of 25mm is completely covered and pressed on the grid area, after 60s, the end of the adhesive tape is held at an angle close to 60° and quickly and smoothly peeled off within 0.5-1.0s; by comparing the coating debris adhered on the adhesive tape after peeling with the damage of the coating in the grid area, the degree of coating peeling is evaluated; the number of intact grid is recorded, and the adhesion retention rate is calculated according to the following formula: adhesion retention rate (%)=(number of intact grid / total number of grid)×100%;

[0067] Erosion resistance: simulate the wet and hot airflow erosion environment in the waste gas treatment process, use self-made dynamic erosion device for testing; place the coating sample in a constant temperature and humidity chamber, and pass in saturated wet air with a temperature of (40±2) °C, a relative humidity of (95±3) %, and a flow rate of (2.0±0.2) m / s, and continuously erode for 720 h (30 days); before and after erosion, accurately weigh the sample mass; after the test, take out the sample, gently brush off the surface loose matter with a soft brush, and weigh again. The erosion resistance is characterized by the mass loss rate, and the calculation formula is: mass loss rate (%) = [(mass before erosion-mass after erosion) / initial mass of the coating] x 100%; the initial mass of the coating is obtained from the mass difference of the substrate before and after coating;

[0068] Table 1 Coating adhesion and erosion resistance test indicators

[0069] Coating adhesion retention rate (%) Erosion resistance (30-day mass loss rate, %) Test Group A 100 2.1 Test Group B 100 2.4 Test Group C 99 2.7 Test Group D 100 2.5 Control Group A 92 8.5 Control Group B 87 12.3 Control Group C 65 24.1 Control Group D 100 2.8 Control Group E 95 5.9 Control Group F 78 16.8 Control Group G 70 19.5 Control Group H 82 15.2 Control Group I 93 7.2 Control Group J 45 31.7 Control Group K 85 9.8

[0070] According to Figure 2 , Figure 3 and Table 1, the composite coatings prepared in the test groups A-D of the present application exhibit excellent adhesion (adhesion retention rate 99-100%) and erosion resistance (30-day mass loss rate 2.1-2.7%), which are superior to all control groups. Specifically, the stable three-dimensional network bonding framework is constructed in the system by the synergistic effect of ethylene-vinyl acetate copolymer and hydroxypropyl methyl cellulose, at the same time, the pre-activated sodium citrate can interact with the active ingredients in peat and calcium hydroxide to form a stable organic-inorganic composite structure in situ during the coating curing process; the two effects mutually strengthen each other, and together increase the firm mechanical bonding force between the coating and the substrate, and make it still maintain the complete structure under the long-term erosion of the wet and hot airflow, thereby improving the durability and service life of the coating;

[0071] In contrast, the control group C, due to the lack of ethylene-vinyl acetate copolymer, results in insufficient bonding network strength, and the adhesion and erosion resistance of the coating decrease (adhesion retention rate 65%, mass loss rate 24.1%); the control group F, due to the lack of hydroxypropyl methyl cellulose, affects the uniform film formation and the integrity of the three-dimensional network of the slurry, causing the coating to be not firmly bonded and easily eroded (adhesion retention rate 78%, mass loss rate 16.8%); the control groups G and H, due to the raw material ratio exceeding the preferred range, respectively result in the coating being too brittle or too loose, the structural stability being poor, and the erosion resistance being weakened; and the control group J, using the prior art, due to the different bonding mechanism, the coating has weak bonding force with the substrate, and is prone to large-area peeling in erosion (adhesion retention rate 45%, mass loss rate 31.7%); these comparison results show that the synergistic bonding and strengthening mechanism formed by the specific components and their preferred ratios in the present application effectively solves the problem of easy peeling and poor durability of the coating.

[0072] Microbial nutrient slow-release performance: The intermittent extraction method was used to simulate the nutrient release behavior of the coating under intermittent humidification conditions. A certain mass (M, accurate to 10.00 g) of unground intact coating particle sample was placed in a conical flask, and a certain volume (V, 100.0 mL) of pH = 7.0 phosphate buffer solution was added as the extraction liquid, and the conical flask was placed in a constant temperature oscillator at (25 ± 1) °C and 150 r / min for oscillation extraction. After 1 h, 1 day, 3 days, 7 days, 14 days and 28 days of extraction, the extraction liquid was taken out and centrifuged and filtered. Then, an equal amount of fresh buffer solution was added to the conical flask, and the next cycle of extraction was continued. The concentration (C_t, unit: mg / L) of total phosphorus (calculated as PO4³⁻) in each extraction liquid was determined by inductively coupled plasma optical emission spectrometer (ICP-OES). The cumulative release amount (m_t, unit: mg) of the nutrient element was obtained by adding the phosphorus mass extracted each time. The cumulative release rate (R_t) of the nutrient element was used to evaluate the slow-release performance, and the calculation formula was: R_t (%) = (m_t) / (M x ω) x 100%. Wherein, ω is the mass fraction (unit: g / g) of total phosphorus in the coating sample measured by elemental analysis. Three parallel experiments were set for each sample, and the results were averaged.

[0073] Table 2 Microbial nutrient slow-release performance detection index

[0074] Initial total phosphorus mass fraction (ω) Extraction 1h Extraction 1d Extraction 3d Extraction 7d Extraction 14d Extraction 28d Test Group A 0.012 1.2 5.8 12.1 22.5 38.7 58.3 Test Group B 0.011 1.0 5.5 11.8 23.0 39.5 60.1 Test Group C 0.010 0.8 4.9 10.5 20.1 35.2 53.8 Test Group D 0.013 1.5 6.2 13.0 24.2 41.0 61.5 Control Group A 0.012 3.5 15.2 25.8 35.1 43.0 48.5 Control Group B 0.008 8.2 30.5 45.3 52.1 55.0 56.2 Control Group C 0.012 2.8 10.5 18.7 28.4 35.9 40.1 Control Group D 0.011 2.5 9.8 17.2 26.0 33.5 38.8 Control Group E 0.005 0.5 2.1 4.0 6.5 9.2 11.0 Control Group F 0.011 4.1 18.3 30.2 39.8 45.5 47.9 Control Group G 0.006 0.3 1.5 3.2 5.8 9.0 12.3 Control Group H 0.015 6.0 22.0 35.1 45.3 50.2 52.0 Control Group I 0.013 2.0 8.5 15.1 22.3 28.0 31.5 Control Group J 0.009 5.5 20.8 32.5 40.2 43.8 44.5 Control Group K 0.000 0.0 0.0 0.0 0.0 0.0 0.0

[0075] According to Table 2, the coatings of test groups A-D all show a sustained and gentle release of phosphorus, with a 28-day cumulative release rate of 53.8-61.5%. In contrast, the control group A, which is not pre-activated with sodium citrate, shows a rapid initial release of phosphorus and a significant decline in the later period, with a 28-day release rate of only 48.5%. This indicates that unactivated sodium citrate cannot effectively form a stable complex structure with peat humic acid and calcium ions, resulting in insufficient nutrient release. The control group B, which lacks sodium citrate, shows a rapid initial release of phosphorus and a stagnant release in the later period, with a 28-day release rate of 56.2%. This indicates that the lack of complex buffering effect of sodium citrate makes it difficult to control the release of nutrients in peat. The control group F, which lacks hydroxypropyl methylcellulose, shows a similar trend of a high initial release and a low later release, with a 28-day release rate of 47.9%. This reflects the incomplete binding network, which affects the coating and slow-release effect of nutrients. The control group E, which uses low-quality peat with low humic acid content, has a severe lack of nutrients, with a 28-day release rate of only 11.0%. This indicates that the quality of peat directly affects the basic nutrient supply capacity of the coating. The control groups G and H have abnormal coating structures or pores due to the excessive proportion of calcium hydroxide or activated carbon components in the formula, resulting in a disorderly phosphorus release curve and cumulative release rates of only 12.3% and 52.0%, respectively. This proves that an imbalance in raw material ratios will damage the structural and functional integrity of the coating. The control group I has a high dosage of potassium dihydrogen phosphate and microcrystalline cellulose during the pre-activation of sodium citrate, which reduces its surface activity and dispersibility, resulting in hindered phosphorus release, with a 28-day release rate of 31.5%. The control group J, which represents the prior art, uses a simple physical mixing and cross-linking process, resulting in a rapid initial release and a significant decline in the later period, with a 28-day release rate of 44.5%. This makes it difficult to achieve long-term slow release. The control group K is a pure physical adsorption coating that contains almost no phosphorus, making it impossible to provide sustained nutrients for microorganisms.

[0076] Therefore, the present application proves that the pre-activation of sodium citrate with specific additives enables it to form a functional coating that can release nutrients for microorganisms in a long-term and balanced manner, effectively solving the problem of uncontrollable and easy loss of nutrients in traditional simple mixed materials. This provides a stable microenvironment support for the long-term colonization and efficient metabolism of microbial communities, thereby ensuring the in-situ bioregeneration ability of the adsorption material.

[0077] Long-term waste gas removal stability: The filler loaded with the coating is packed in a small dynamic bio-trickling filter (or adsorption column) for testing under continuous operation conditions. A mixed gas (mainly containing hydrogen sulfide, methyl mercaptan, ammonia, ethyl acetate, and odor concentration fluctuating between 5000-20000 dimensionless) simulating the odor components of a typical kitchen waste treatment plant is taken as the processing object, and the gas flow is controlled to make the empty bed residence time (EBRT) 40s, the inlet gas temperature (30±2)℃, and the relative humidity >95%. During the system startup stage, the intermittent spraying of nutrient solution is used for microbial biofilm formation and domestication. After entering the stable operation period, only deionized water required to maintain humidity is supplemented regularly; the odor concentration at the inlet and outlet of the device is measured by the three-point comparison method every day, and the daily removal rate is calculated; the removal rate data is recorded every day for 90 days of continuous operation. The long-term waste gas removal stability is comprehensively evaluated by the average value, standard deviation of the removal rate, and the proportion of days during the operation period when the removal rate is lower than the preset target value (such as 90%); the removal rate calculation formula is: odor concentration removal rate (%)=(inlet odor concentration-outlet odor concentration) / inlet odor concentration×100%;

[0078] Table 3 Long-term waste gas removal stability test indicators

[0079] Average removal rate (%) Removal rate standard deviation Days with removal rate < 90% Test Group A 97.2 1.8 0% Test Group B 96.8 2.1 0% Test Group C 96.5 2.4 0% Test Group D 97.0 1.9 0% Control Group A 91.5 5.6 22% Control Group B 88.3 7.2 41% Control Group C 82.1 9.8 68% Control Group D 93.7 4.3 12% Control Group E 90.2 6.1 31% Control Group F 85.4 8.5 55% Control Group G 84.7 8.9 59% Control Group H 86.9 7.7 48% Control Group I 92.1 4.9 18% Control Group J 76.5 12.3 81% Control Group K First 15 days: >95% After 15 days: <50% Extremely high 90%

[0080] According to Table 3, the average removal rate of the test groups A-D of the present application to the fluctuating odor is as high as 96.5-97.2% in the 90-day long-term operation, and the removal rate is extremely stable, and there is no case of less than 90% during the operation period, which verifies the effectiveness of the “adsorption-biodegradation” synergistic circulation mechanism in the composite coating. The gradient pore structure promotes the mass transfer of pollutants to microorganisms, and the stable nutrient supply and coating structure provide a persistent guarantee for microbial activity, so that the system can maintain high-efficiency and stable removal performance in long-term operation without interrupting the operation for filler replacement or off-line regeneration;

[0081] In contrast, the performance of the control groups is attenuated to varying degrees due to the lack of key technical features of the present application; specifically, control group A is affected in its dispersion in the coating and its ability to form a stable complex structure with peat and calcium hydroxide due to the lack of pre-activation of sodium citrate, resulting in uneven nutrient supply and decreased coating structure stability; control group B completely lacks the core regulatory link of complex stability and nutrient release due to the lack of sodium citrate, restricting the long-term colonization and activity maintenance of microorganisms; control group C lacks sufficient bonding network strength due to the lack of use of ethylene-vinyl acetate copolymer, resulting in structural damage and component loss of the coating under long-term hot and humid washing; control group D affects the selective adsorption and enrichment effect of specific polar pollutants due to the use of ordinary zeolite without regular pore channels and suitable surface properties; control group E is severely deficient in its function as a core nutrient source and water-retaining carrier for microorganisms due to the use of low-quality peat with high mineralization and low humic acid content; control group F affects the film-forming property of the slurry and the integrity of the three-dimensional network structure due to the lack of hydroxypropyl methyl cellulose, thereby weakening the homogeneity and adhesion of the coating; control group G and H have a serious imbalance in the formula ratio, which is beyond the effective synergy range of functional components, resulting in degradation of the overall performance of the coating; control group I may interfere with the normal formation of the complex structure due to the use of excessive potassium dihydrogen phosphate and microcrystalline cellulose during the activation of sodium citrate; control groups J and K represent two prior art solutions, the former has weak coating adhesion and easy nutrient loss due to simple physical coating and cross-linking; the latter is a purely physical adsorption coating and has no biological regeneration ability, and its performance rapidly collapses after adsorption saturation.

[0082] In summary, the present application introduces sodium citrate pre-activated by a specific process to form a stable organic-inorganic complex structure in situ with humic acid in peat and calcium hydroxide during the solidification process, which cooperates with the three-dimensional network skeleton constructed by ethylene-vinyl acetate copolymer and hydroxypropyl methyl cellulose to effectively improve the structural stability, adhesion, and nutrient element release performance of the coating in a humid flue gas environment; not only does it improve the problems of easy peeling, rapid nutrient loss, and difficult long-term maintenance of microbial activity of traditional composite coatings, but also optimizes the mass transfer path from the adsorption site to the microbial community through the gradient pore channels formed by activated carbon, zeolite, and peat, achieving efficient synergy and dynamic balance between adsorption and biodegradation at the microscale, thereby enabling the coating to have excellent in-situ and continuous biological regeneration capacity, and maintaining a high and stable removal efficiency for a long time when treating low-concentration and fluctuating flue gas.

[0083] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only preferred examples of the present application and are not intended to limit the present application. Various changes and improvements can be made to the present application without departing from the spirit and scope of the present application, and such changes and improvements are all within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for the preparation of a composite coating for in-situ biological regeneration of adsorption materials, characterized in that, It comprises the following steps: S1, the activated carbon, zeolite, peat are respectively placed in the crusher to break, and then the 150-400 mesh material is selected, and then the material is put into the drying equipment, and dried at 80-105 DEG C, and the moisture content of the material is less than 2%; S2, the ethylene-vinyl acetate copolymer and hydroxypropyl methyl cellulose are put into the container with stirring and heating function, and stirred until the mixture is completely dissolved, dispersed uniformly, and the transparent and no obvious particle viscous colloid is formed, then the pre-activated sodium citrate is added and stirred to form a slurry matrix with uniform film forming and bonding properties; S3, the material with water content less than 2% is added into the slurry matrix in turn, and the remaining deionized water is added, and then stirred at room temperature until the uniform and stable paste slurry without obvious particle agglomeration is formed; S4, the paste slurry is placed in the vacuum defoaming device, and the viscosity is adjusted to 2000-5000 mPa·s according to the viscosity of the slurry, and the homogeneous slurry is obtained; S5, the homogeneous slurry is coated on the surface of the substrate by spraying, dipping or scraping, and the wet coating thickness is 0.5-2.0 mm, and then it is moved into the curing equipment to form a composite coating with stable structure, pore through and firm combination with the substrate; In the S1, the zeolite adopts 150-400 mesh particle size of clinoptilolite or mordenite, and the clinoptilolite and mordenite have regular pore structure, good ion exchange performance and moderate surface acidity; In the S1, the peat adopts herbaceous peat or moss peat treated by crushing and drying, which has high humic acid content, rich fiber structure and strong water and fertilizer retention capacity; The pre-activation treatment of sodium citrate in S2 comprises the following steps: Put sodium citrate, potassium dihydrogen phosphate and microcrystalline cellulose into the planetary ball mill jar, mix and grind at room temperature with a speed of 80-150 r / min for 8-12 min; Then, it is transferred to the stirring container containing ethanol aqueous solution, stirred at a speed of 180-250 r / min for 6-8 min to make it fully wet and form a uniformly dispersed suspension slurry; finally, it is placed and aged in a closed environment for 12-15 min to obtain modified sodium citrate with good dispersibility and surface activity; The amount of potassium dihydrogen phosphate is 6-9% of the total mass of sodium citrate; the amount of microcrystalline cellulose is 0.8-1.2% of the total mass of sodium citrate; the ethanol aqueous solution is prepared by mixing ethanol and deionized water in a volume ratio of 1:3-1:5, and the amount is 1.2-1.8 times the total mass of sodium citrate, and the temperature is 35-40 DEG C.

2. The method of claim 1, wherein the method further comprises: In the S2, the ethylene-vinyl acetate copolymer is selected from granular or powdery copolymer with 18-40% vinyl acetate content.

3. The method of claim 1, wherein the method further comprises: The S2, the amount of deionized water is 30-50% of the total amount; the container with stirring and heating function is continuously stirred at 400-500 r / min at 50-60℃ for 30-40 min, and then 15-20 min after adding the pre-activated sodium citrate, the same temperature and speed are maintained.

4. The method of claim 1, wherein the method further comprises: The S4, the slurry viscosity adjustment includes the following cases: When the slurry viscosity is too high, add a small amount of deionized water, each addition amount is not more than 2% of the total mass of the slurry, and cooperate with 50-100 r / min stirring speed for 5-10 min, until the viscosity decreases to the target range; When the slurry viscosity is too low, the slurry is placed in an environment of 25-35℃, and continuously stirred at 30-50 r / min for 10-40 min, the viscosity is increased to the target range by water evaporation and system self-thickening.

5. The composite coating for in-situ biological regeneration of adsorbent material prepared by the method of any one of claims 1-4, wherein the composite coating is characterized by: The following raw materials are included: Calcium hydroxide 30-70wt%; activated carbon 10-50wt%; zeolite 5-30wt%; peat 5-25wt%; ethylene-vinyl acetate copolymer 3-12wt%; hydroxypropyl methyl cellulose 0.1-1wt%; sodium citrate 0.05-0.8wt%; deionized water 1-8wt%; wherein: The ethylene-vinyl acetate copolymer and hydroxypropyl methyl cellulose synergistically form a three-dimensional network bonding framework in deionized water, firmly covering and cross-linking calcium hydroxide, activated carbon, zeolite and peat, and forming a stable porous coating structure; the microporous structure of activated carbon and zeolite and the abundant mesoporous and macroporous structure of peat are interconnected to form a composite network with gradient pore size distribution.

6. The composite coating for in-situ biological regeneration of adsorbent material according to claim 5, wherein, The amount of calcium hydroxide is 35-45wt%; the amount of activated carbon is 25-35wt%; the amount of zeolite is 10-15wt%; the amount of peat is 10-18wt%; the amount of ethylene-vinyl acetate copolymer is 5-8wt%; the amount of hydroxypropyl methyl cellulose is 0.2-0.6wt%; the amount of sodium citrate is 0.1-0.4wt%; the amount of deionized water is 2-5wt%.

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