Water-based method for treating large-volume low-concentration exhaust gas

Abstract

The application relates to the technical field of waste gas treatment, and particularly discloses a waste gas treatment liquid for treating large-wind-amount low-concentration waste gas by a water-based method. The waste gas treatment liquid for treating large-wind-amount low-concentration waste gas by the water-based method comprises a surfactant, a defoaming agent, a dissolution promoter and water; the surfactant can be any one or more of polyoxyethylene alkyl ether, polyoxyethylene alkyl ether and polyoxyethylene fatty acid ester; the dissolution promoter can be any one or more of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether and triethylene glycol monobutyl ether; and the defoaming agent is any one or more of butanol, dimethyl silicone oil, silicone and polyether-modified polysiloxane. The waste gas absorption liquid obtained by the application has obvious improvement in absorption efficiency for methanol, butanol, benzene, toluene, xylene, ethyl acetate, dichloromethane and acetone, and the absorption efficiency of the waste gas absorption liquid for aromatic hydrocarbons, halogenated hydrocarbons, alcohols, ketones and ester pollutants is improved.

Description

Technical Field

[0001] This application relates to the field of waste gas treatment, and more specifically, it relates to a water-based waste gas absorption liquid for treating large volumes of low-concentration waste gas. Background Technology

[0002] With the rapid development of industries such as industrial manufacturing, coating, packaging and printing, and chemicals, the emission of harmful waste gases has become increasingly prominent. Among them, large-volume, low-concentration waste gases have become a key and difficult point in air pollution control due to their large emission volume, wide coverage, and complex composition. If mixed waste gases of aromatics, halogenated hydrocarbons, alcohols, ketones, and esters are discharged directly without proper treatment, they will not only damage the ecological environment but also seriously threaten human health if inhaled or exposed to the skin. These are key controlled VOCs waste gases.

[0003] In related technologies, pure water is used to treat large volumes of low-concentration waste gas. Water is used as a solvent to dissolve the waste gas, so that the pollutants such as aromatic hydrocarbons, halogenated hydrocarbons, and alcohols, ketones and esters in the waste gas are transferred to the liquid phase, thereby achieving gas-liquid separation. This method is both environmentally friendly and safe, and there is no need to worry about secondary pollution caused by the volatilization of organic solvents. However, the absorption efficiency is low and it is still difficult to meet the actual needs of waste gas treatment. Summary of the Invention

[0004] In order to improve the absorption efficiency of waste gas absorbent liquid for aromatic hydrocarbons, halogenated hydrocarbons, and alcohol, ketone and ester pollutants, this application provides a water-based waste gas absorbent liquid for treating large volumes of low-concentration waste gas.

[0005] In the first aspect, this application provides a water-based method for treating large volumes of low-concentration waste gas, which adopts the following technical solution:

[0006] A water-based method for treating large volumes of low-concentration waste gas using a waste gas absorption liquid comprises the following raw materials in parts by weight: 100 parts surfactant, 5-20 parts defoamer, 100-200 parts dissolution promoter, and 5000 parts water.

[0007] The surfactant may be any one or more of polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene fatty acid ester; the solubilizer may be any one or more of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether; and the defoamer may be any one or more of butanol, dimethyl silicone oil, silicone, and polyether-modified polysiloxane.

[0008] By employing the above scheme, water is used as the core solvent for waste gas treatment. Alcohol pollutants such as methanol, ethanol, propanol, butanol, and hexanol contain hydroxyl groups, which can form intermolecular hydrogen bonds with water molecules. After physical dissolution, these hydrogen bonds associate, allowing the alcohol pollutants to quickly diffuse into the aqueous phase and dissolve stably. Aromatic pollutants such as benzene, toluene, ethylbenzene, and xylene exhibit van der Waals forces between water molecules; combined with surfactants, absorption efficiency can be improved. Ester pollutants such as ethyl acetate, propyl acetate, and methyl butyrate contain ester groups, which interact with water molecules via dipole-dipole interactions. Physical dissolution of ester pollutants achieves gas-liquid separation, thus treating the waste gas. Halogenated hydrocarbon pollutants such as dichloromethane, monochloroethane, and dichloroethane can be physically dissolved in water. Ketone pollutants such as acetone and butanone contain lone pairs of electrons in their carbonyl oxygen atoms, exhibiting strong polarity. These atoms can form hydrogen bonds with water molecules, dissolution promoters, and surfactant molecules, absorbing ketone waste gas through hydrogen bond association and physical dissolution. It is evident that using water as the core treatment solvent is fundamental to improving the absorption efficiency of pollutants such as aromatic hydrocarbons, halogenated hydrocarbons, alcohols, ketones, and esters.

[0009] Adding surfactants to water as the core treatment solvent can reduce gas-liquid interfacial tension, enhance the solubilization and mass transfer processes of waste gas, and thus ensure the absorption efficiency of aromatic hydrocarbons, halogenated hydrocarbons, alcohols, ketones, and esters. Defoamers are used to suppress the large amount of foam generated during absorption due to airflow agitation and surfactant action, preventing excessive foam from affecting gas-liquid contact efficiency. Adding dissolution promoters containing hydrophobic alkyl chains and hydrophilic ether bonds can bind to halogenated hydrocarbon pollutant molecules through hydrophobic interactions and van der Waals forces, significantly improving the apparent solubility of halogenated hydrocarbon pollutants in the aqueous phase. Furthermore, it can improve the solubility of aromatic hydrocarbons, alcohols, ketones, and esters in water or construct a synergistic absorption system, thereby enhancing the overall treatment effect.

[0010] Preferably, the waste gas absorption liquid comprises the following raw materials in parts by weight: 100 parts surfactant, 15 parts defoamer, 150 parts dissolution promoter, and 5000 parts water.

[0011] The optimal raw material for the waste gas absorption liquid in this application is a mixture of 100 parts surfactant, 15 parts defoamer, 150 parts dissolution promoter, and 5000 parts water, which can significantly improve the waste gas absorption efficiency.

[0012] Preferably, the surfactant is a compound of polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene fatty acid ester; the mass ratio of the polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene fatty acid ester is 4:2:1.

[0013] By adopting the above scheme, polyoxyethylene alkyl ether is used as the main surfactant to ensure the system's low foaming and biodegradability. Polyoxyethylene alkyl phenyl ether enhances the solubilization of aromatic pollutants, and polyoxyethylene fatty acid ester improves the system's solubility for ester and ketone pollutants. The solubility effect is significantly higher than that of a single surfactant.

[0014] Preferably, the polyoxyethylene alkyl ether is obtained through pretreatment, specifically including the following steps: glacial acetic acid is added to the polyoxyethylene alkyl ether, stirred at a rate of 300-400 r / min, heated to 50-55℃ and stirred until transparent, 30% hydrogen peroxide is added dropwise at 1-2 mL / min, after which the temperature is raised to 70-75℃ and the reaction is maintained for 4-5 hours, cooled to 40℃, pH adjusted to 6.5-7.5, distilled and washed, allowed to stand and separate into layers, the upper liquid is retained, filtered, and the pretreated polyoxyethylene alkyl ether is obtained.

[0015] By adopting the above scheme, the polyoxyethylene alkyl ether is pretreated by oxidation, which improves the dispersibility of the polyoxyethylene alkyl ether in aqueous solution, optimizes the end group structure, enhances the affinity of the target pollutant, improves the gas-liquid mass transfer efficiency, and improves the overall pollutant absorption efficiency. It can also extend the service life of the waste gas absorption liquid. In addition, the pretreated polyoxyethylene alkyl ether will self-assemble to form a micelle structure with a hydrophobic core and a hydrophilic shell. The hydrophobicity of the halogenated hydrocarbon molecules causes them to spontaneously enter the hydrophobic core of the micelles and be encapsulated by surfactant molecules, thereby further improving the absorption efficiency of halogenated hydrocarbon pollutants. Add glacial acetic acid to polyoxyethylene alkyl ether and stir at a rate of 300-400 r / min. Heat to 50-55℃ and stir until transparent to provide a weakly acidic reaction environment, which is beneficial for the subsequent addition of hydrogen peroxide, activates the oxidation activity of hydrogen peroxide, and provides a uniform reaction interface for subsequent oxidation reactions. Add 30% mass concentration hydrogen peroxide and heat to 70-75℃, and keep the reaction at this temperature for 4-5 hours to oxidize and decompose residual alkylphenols, short-chain polyethylene glycol byproducts, colored impurities, etc. in polyoxyethylene alkyl ether. At the same time, moderately oxidize a small number of unsaturated groups at the end of the polyoxyethylene alkyl ether molecule to improve the hydrophilicity and stability of polyoxyethylene alkyl ether, enhance the adsorption capacity of gas-liquid interface, and thus further improve the absorption efficiency of waste gas absorption liquid.

[0016] Preferably, the solubility promoter is a compound of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether; the mass ratio of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether is 3:4:3.

[0017] By adopting the above scheme, the short EO segment of ethylene glycol monobutyl ether focuses on dissolving non-polar aromatic pollutants, while the long EO segment of diethylene glycol monobutyl ether focuses on dissolving strongly polar alcohols and ketones. It can also improve the compatibility of ethylene glycol monobutyl ether and triethylene glycol monobutyl ether. Triethylene glycol monobutyl ether focuses on dissolving aromatic hydrocarbons, alcohols, and esters. It can also improve the water solubility and stability of the dissolution promoter. The mixed system formed by the three covers the solubility range from weakly polar to strongly polar, and can simultaneously improve the apparent solubility of aromatic hydrocarbons, halogenated hydrocarbons, esters, alcohols, and ketones in water, thereby improving the absorption efficiency of the waste gas absorption liquid.

[0018] Preferably, the diethylene glycol monobutyl ether is obtained through pretreatment, specifically by adding diethylene glycol monobutyl ether, a 40% mass concentration dimethylamine aqueous solution, and dried γ-alumina to a high-pressure sealed reactor, mixing, stirring at a rate of 200-300 r / min, heating to 120-130℃ at a rate of 2℃ / min, maintaining the temperature for 6-8 hours, distilling and purifying, and drying to obtain the pretreated diethylene glycol monobutyl ether.

[0019] By adopting the above scheme, diethylene glycol monobutyl ether is pretreated to introduce tertiary amine groups into the terminal hydroxyl groups of diethylene glycol monobutyl ether, thereby adding charge transfer and hydrogen bonding sites, reducing the surface tension of the absorbent, improving the gas-liquid mass transfer efficiency, optimizing the dispersion performance of the absorbent, and thus improving the solubility of the waste gas absorbent, thereby increasing the absorption efficiency. An aqueous solution of diethylene glycol monobutyl ether dimethylamine and γ-alumina are mixed and stirred at a rate of 200-300 r / min to ensure full contact between the two. The temperature is then increased to 120-130℃ at a rate of 2℃ / min and maintained for 6-8 hours to ensure complete amination reaction, converting hydroxyl groups into amino groups as much as possible. This reduces the surface tension of the absorbent and improves the gas-liquid mass transfer efficiency. Furthermore, it significantly enhances the compatibility between ethylene glycol monobutyl ether and triethylene glycol monobutyl ether, thereby facilitating the absorption of non-polar aromatic hydrocarbons, strongly polar alcohols, and esters by the waste gas absorbent, improving the solubility of the absorbent and thus increasing the absorption efficiency.

[0020] Preferably, the defoamer is a compound of dimethyl silicone oil, silicone, and polyether-modified polysiloxane; the mass ratio of the dimethyl silicone oil, silicone, and polyether-modified polysiloxane is 4:3:3.

[0021] By adopting the above scheme, dimethyl silicone oil can quickly diffuse to the surface of the foam film, reduce the surface tension of the film, cause the foam film to rupture, and play a role in defoaming. The silica particles in the silicone are adsorbed at the gas-liquid interface, which can hinder the repair and recombination of the foam film. The polyether modified polysiloxane can uniformly disperse dimethyl silicone oil and silicone in the water-based system, prevent dimethyl silicone oil and silicone from agglomerating and stratifying, ensure gas-liquid mass transfer efficiency, and thus improve the waste gas absorption efficiency.

[0022] Secondly, this application provides a method for preparing a water-based waste gas absorption liquid for treating large volumes of low-concentration waste gas according to any of the above claims, specifically achieved through the following technical solution:

[0023] A method for preparing a waste gas absorption liquid for treating large volumes of low-concentration waste gas using a water-based method includes the following steps: mixing the raw materials of the waste gas absorption liquid and stirring evenly to obtain the waste gas absorption liquid.

[0024] Thirdly, this application provides a water-based treatment process for treating large volumes of low-concentration waste gas, specifically achieved through the following technical solution:

[0025] A water-based treatment process for treating large volumes of low-concentration waste gas includes any of the aforementioned waste gas absorbent liquids. The specific process involves: preparing the waste gas absorbent liquid in an absorbent liquid storage tank; loading the prepared absorbent liquid into an absorption tower through an inlet; and introducing the waste gas into the absorption tower through a gas collection hood, where the gas fully contacts the absorbent liquid in the packing layer to complete the absorption process. The absorption conditions are: absorption temperature controlled at 20-40℃, pressure at atmospheric pressure, and maintaining an absorbent-to-gas ratio of 1-8 m³ / s. 3 / m 3 The resulting absorbent containing waste gas was obtained.

[0026] Preferably, the waste gas in the absorbent containing the waste gas is removed by membrane separation, heating distillation, or adsorption, and the absorbent is then recovered.

[0027] The absorbent containing waste gas obtained in this application can be used to remove waste gas and recover the absorbent by membrane separation, thermal distillation, or adsorption. Thermal distillation is the most common method, where different waste gases are separated stepwise based on their boiling point differences: halogenated hydrocarbons are recovered at 30-40℃, alcohols and ketones at 50-60℃, and aromatics and esters at 70-80℃. High-boiling-point surfactants, defoamers, and solubilizers remain in the liquid phase, thus recovering the absorbent. Membrane separation uses hydrophobic microporous membranes, such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF) membranes. Waste gas molecules preferentially dissolve and permeate through the membrane pores, while the absorbent is retained due to its hydrophilicity, thus recovering the absorbent. Adsorption uses adsorbents such as activated carbon, resin, and molecular sieves, which adsorb waste gas through van der Waals forces and hydrophobic interactions. The filtrate is then filtered and used as the absorbent, which is then recovered.

[0028] In summary, this application includes at least one of the following beneficial technical effects:

[0029] This application improves the absorption efficiency of the waste gas absorption liquid for aromatic hydrocarbons, halogenated hydrocarbons, and alcohol, ketone, and ester pollutants by controlling the types and amounts of each raw material in the waste gas absorption liquid, achieving absorption efficiencies of 96.0%, 97.1%, 93.5%, 97.0%, 97.9%, 98.0%, 98.8%, and 92.2% for methanol, butanol, benzene, toluene, xylene, ethyl acetate, dichloromethane, and acetone, respectively. This results in a higher treatment effect on the waste gas.

[0030] This application utilizes a compound of polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene fatty acid ester as a surfactant, and controls the dosage of polyoxyethylene alkyl ether, polyoxyethylene alkyl ether, and polyoxyethylene fatty acid ester to achieve absorption efficiencies of 97.2%, 97.5%, 94.7%, 98.2%, 98.5%, 98.4%, 99.0%, and 95.5% for methanol, butanol, benzene, toluene, xylene, ethyl acetate, dichloromethane, and acetone in the waste gas absorbent liquid, respectively. This further improves the absorption efficiency of the waste gas absorbent liquid for aromatic hydrocarbons, halogenated hydrocarbons, and alcohol, ketone, and ester pollutants.

[0031] This application improves the absorption efficiency of the waste gas absorbent liquid for aromatic hydrocarbons, halogenated hydrocarbons, and alcohol-ketone-ester pollutants by pretreating polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, and polyoxyethylene fatty acid esters as surfactants. This is achieved by pretreating polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, and polyoxyethylene fatty acid esters as surfactants, resulting in absorption efficiencies of 97.5%, 98.0%, 95.2%, 98.5%, 98.9%, 98.6%, 99.3%, and 96.0%, respectively.

[0032] This application utilizes a compound of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether as a solubilizer, and controls the dosage of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether to achieve absorption efficiencies of 98.8%, 99.0%, 97.2%, 99.0%, 99.3%, 99.5%, 99.5%, and 98.2% for methanol, butanol, benzene, toluene, xylene, ethyl acetate, dichloromethane, and acetone in the waste gas absorbent liquid, respectively. This further improves the absorption efficiency of the waste gas absorbent liquid for aromatic hydrocarbons, halogenated hydrocarbons, and alcohol, ketone, and ester pollutants.

[0033] This application improves the absorption efficiency of the waste gas absorbent liquid for aromatic hydrocarbons, halogenated hydrocarbons, and alcohol, ketone, and ester pollutants by pretreating diethylene glycol monobutyl ether (EDBME) with a compound of EDBME, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether as a solubility promoter. This is achieved by pretreating EDBME with a compound of EDBME, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether as a solubility promoter, resulting in absorption efficiencies of 99.3%, 99.2%, 98.9%, 99.2%, 99.6%, 99.6%, 99.6%, and 99.1%, respectively.

[0034] This application utilizes a compound of dimethyl silicone oil, silicone, and polyether-modified polysiloxane as a defoamer, and controls the dosage of dimethyl silicone oil, silicone, and polyether-modified polysiloxane to achieve absorption efficiencies of 99.4%, 99.3%, 99.0%, 99.3%, 99.7%, 99.7%, 99.7%, and 99.3% for methanol, butanol, benzene, toluene, xylene, ethyl acetate, dichloromethane, and acetone in the waste gas absorption liquid, respectively. This further improves the absorption efficiency of the waste gas absorption liquid for aromatic hydrocarbons, halogenated hydrocarbons, and alcohol, ketone, and ester pollutants. Detailed Implementation

[0035] The following detailed description, in conjunction with specific embodiments, further illustrates this application. All the raw materials used in this application are commercially available products and are intended to fully disclose the raw materials used in this application; they should not be construed as limiting the source of the raw materials. Specifically, they are: polyoxyethylene alkyl ether, AEO-type nonionic surfactant, lauryl polyoxyethylene ether, model AEO-9; polyoxyethylene alkyl phenyl ether, TRITON X-100, manufactured by SIGMA-ALDRICH Japan; polyoxyethylene fatty acid ester, with an active ingredient content of 99%; ethylene glycol monobutyl ether, with an active ingredient content of 99%; diethylene glycol monobutyl ether, with an active ingredient content of 99.9%; triethylene glycol monobutyl ether, with an active ingredient content of 99%; γ-alumina, with a particle size of 10 nm; dimethyl silicone oil, with an active ingredient content of 99%; silicone, with an active ingredient content of 36%; and polyether-modified polysiloxane, with an active ingredient content of 60%.

[0036] Example 1

[0037] Example 1: Waste gas absorption liquid was prepared through the following steps:

[0038] Mix all the raw materials of the waste gas absorption liquid and stir evenly to obtain the waste gas absorption liquid. The waste gas absorption liquid includes the following raw materials: 100g surfactant (polyoxyethylene alkyl ether), 15g defoamer (dimethyl silicone oil), 100g solubilizer (ethylene glycol monobutyl ether), and 5000mL water.

[0039] Example 2-3

[0040] The difference between the waste gas absorption liquid in Examples 2-3 and Example 1 is that the amount of dissolution accelerator is different. The amount of dissolution accelerator (ethylene glycol monobutyl ether) is 150g and 200g respectively, while the amount and type of other raw materials are the same as in Example 1.

[0041] Example 4

[0042] The difference between the waste gas absorption liquid in Example 4 and Example 2 is that the surfactant is a compound of polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene fatty acid ester. The amounts of polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene fatty acid ester are 57.1g, 28.6g, and 14.3g, respectively. The amount and type of other raw materials are the same as in Example 2.

[0043] Example 5

[0044] The difference between the waste gas absorption liquid in Example 5 and Example 4 is that the polyoxyethylene alkyl ether was obtained through pretreatment. Specifically, 15g of glacial acetic acid was added to 1kg of polyoxyethylene alkyl ether, stirred at a rate of 300r / min, heated to 50℃ and stirred until transparent, and 50mL of 30% hydrogen peroxide was added dropwise at 1mL / min. After the addition was completed, the temperature was raised to 70℃ and kept at that temperature for 4h. The temperature was then lowered to 40℃, the pH was adjusted to 7, and the mixture was washed by distillation. After standing and separating into layers, the upper liquid was retained and filtered to obtain the pretreated polyoxyethylene alkyl ether.

[0045] Example 6

[0046] The difference between the waste gas absorption liquid in Example 6 and Example 5 is that the dissolution promoter is a compound of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether. The amounts of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether are 45g, 60g, and 45g, respectively. The dosage and type of other raw materials are the same as in Example 5.

[0047] Example 7

[0048] The difference between the waste gas absorption liquid in Example 7 and Example 6 is that the diethylene glycol monobutyl ether was obtained through pretreatment. Specifically, γ-alumina was calcined at 500°C for 2 hours to obtain dried γ-alumina; 1 kg of diethylene glycol monobutyl ether, 400 mL of 40% dimethylamine aqueous solution and 20 g of dried γ-alumina were mixed, stirred at a rate of 200 r / min, heated to 120°C at a rate of 2°C / min, and kept at this temperature for 6 hours. After distillation and purification, and drying, the pretreated diethylene glycol monobutyl ether was obtained.

[0049] Example 8

[0050] The difference between the waste gas absorption liquid in Example 8 and Example 7 is that the defoamer is a compound of dimethyl silicone oil, silicone, and polyether-modified polysiloxane. The amounts of dimethyl silicone oil, silicone, and polyether-modified polysiloxane are 6g, 4.5g, and 4.5g, respectively. The amount and type of other raw materials are the same as in Example 7.

[0051] Comparative Example 1

[0052] The preparation method of the waste gas absorption liquid in Comparative Example 1 is exactly the same as that in Example 1, except that no surfactant is added, and the other raw materials and dosages are the same as in Example 1.

[0053] Comparative Example 2

[0054] The preparation method of the waste gas absorption liquid in Comparative Example 2 is exactly the same as that in Example 1, except that no defoamer is added, and the other raw materials and dosages are the same as in Example 1.

[0055] Comparative Example 3

[0056] The preparation method of the waste gas absorption liquid in Comparative Example 3 is exactly the same as that in Example 1, except that no dissolution promoter is added, and the other raw materials and dosages are the same as in Example 1.

[0057] Performance testing

[0058] The waste gas absorption liquids of different Examples 1-8 and Comparative Examples 1-3 were tested using the following methods. The test results are shown in Table 1.

[0059] The waste gas absorbents obtained in Examples 1-8 and Comparative Examples 1-3 were used to treat large volumes of low-concentration waste gas. The specific treatment process was as follows: the waste gas absorbent was prepared in an absorbent storage tank, and the prepared absorbent was loaded into the absorption tower through the inlet. The organic waste gas was introduced into the absorption tower through a gas collection hood, and the gas was fully contacted with the absorbent in the packing layer to complete the absorption process. The absorption conditions were: the absorption temperature was controlled at 20-40℃, the pressure was at atmospheric pressure, and the absorbent-to-gas ratio was maintained at 1-8 m³ / s. 3 / m 3 Control the exhaust gas treatment air volume to 10000 Nm 3 / h, an absorbent containing waste gas is obtained. The concentrations of pollutants such as alcohols (methanol, butanol), aromatics (benzene, toluene, xylene), esters (ethyl acetate), halogenated hydrocarbons (dichloromethane), and ketones (acetone) are detected at the inlet and outlet before treatment. The absorption efficiency is calculated based on the corresponding inlet and outlet pollutant concentrations.

[0060] Table 1 Performance test results of different waste gas absorption liquids

[0061]

[0062] The test results in Table 1 show that the waste gas absorption liquid obtained in this application achieves the highest absorption efficiencies of 99.4%, 99.3%, 99.0%, 99.3%, 99.7%, 99.7%, 99.7%, and 99.3% for methanol, butanol, benzene, toluene, xylene, ethyl acetate, dichloromethane, and acetone, respectively. This improves the absorption efficiency of the waste gas absorption liquid for aromatic hydrocarbons, halogenated hydrocarbons, and alcohol, ketone, and ester pollutants, demonstrating high treatment effectiveness and meeting the needs for treating large volumes of low-concentration waste gas.

[0063] Based on the performance test data of the waste gas absorption liquids in Examples 1-3, it was found that the absorption efficiencies of the waste gas absorption liquid in Example 2 for methanol, butanol, benzene, toluene, xylene, ethyl acetate, dichloromethane, and acetone were 96.0%, 97.1%, 93.5%, 97.0%, 97.9%, 98.0%, 98.8%, and 92.2%, respectively, all higher than those in Examples 1 and 3. This indicates that adding 150 parts of dissolution promoter to the raw materials of the waste gas absorption liquid yields the best results and can further improve the absorption efficiency of the waste gas absorption liquid for aromatic hydrocarbons, halogenated hydrocarbons, and alcohol, ketone, and ester pollutants.

[0064] Combining the performance test data of the waste gas absorption liquids from Examples 4 and 2, it was found that the absorption efficiencies of the waste gas absorption liquid in Example 4 for methanol, butanol, benzene, toluene, xylene, ethyl acetate, dichloromethane, and acetone were 97.2%, 97.5%, 94.7%, 98.2%, 98.5%, 98.4%, 99.0%, and 95.5%, respectively, all higher than those in Example 2. This indicates that using a compound of polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene fatty acid ester as a surfactant, and controlling the mass ratio of polyoxyethylene alkyl ether, polyoxyethylene alkyl ether, and polyoxyethylene fatty acid ester to 4:2:1, can further improve the absorption efficiency of the waste gas absorption liquid for aromatic hydrocarbons, halogenated hydrocarbons, and alcohol-ketone-ester pollutants.

[0065] Combining the performance test data of the waste gas absorption liquids from Examples 4 and 5, it was found that the absorption efficiencies of the waste gas absorption liquid in Example 5 for methanol, butanol, benzene, toluene, xylene, ethyl acetate, dichloromethane, and acetone were 97.5%, 98.0%, 95.2%, 98.5%, 98.9%, 98.6%, 99.3%, and 96.0%, respectively, all higher than those in Example 4. This indicates that pretreatment of the polyoxyethylene alkyl ether in the surfactant can further improve the absorption efficiency of the waste gas absorption liquid for aromatic hydrocarbons, halogenated hydrocarbons, and alcohol-ketone-ester pollutants.

[0066] Combining the performance test data of the waste gas absorption liquids from Examples 5 and 6, it was found that the absorption efficiencies of the waste gas absorption liquid in Example 6 for methanol, butanol, benzene, toluene, xylene, ethyl acetate, dichloromethane, and acetone were 98.8%, 99.0%, 97.2%, 99.0%, 99.3%, 99.5%, 99.5%, and 98.2%, respectively, all higher than those in Example 5. This indicates that using a compound of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether as a dissolution promoter, and controlling the mass ratio of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether to be 3:4:3, can further improve the absorption efficiency of the waste gas absorption liquid for aromatic hydrocarbons, halogenated hydrocarbons, and alcohol, ketone, and ester pollutants.

[0067] Combining the performance test data of the waste gas absorption liquids from Examples 6 and 7, it was found that the absorption efficiencies of the waste gas absorption liquid in Example 7 for methanol, butanol, benzene, toluene, xylene, ethyl acetate, dichloromethane, and acetone were 99.3%, 99.2%, 98.9%, 99.2%, 99.6%, 99.6%, 99.6%, and 99.1%, respectively, all higher than those in Example 6. This indicates that pretreatment with diethylene glycol monobutyl ether in the dissolution promoter can further improve the absorption efficiency of the waste gas absorption liquid for aromatic hydrocarbons, halogenated hydrocarbons, and alcohol, ketone, and ester pollutants.

[0068] Combining the performance test data of the waste gas absorption liquids from Examples 7 and 8, it was found that the absorption efficiencies of the waste gas absorption liquid in Example 8 for methanol, butanol, benzene, toluene, xylene, ethyl acetate, dichloromethane, and acetone were 99.4%, 99.3%, 99.0%, 99.3%, 99.7%, 99.7%, 99.7%, and 99.3%, respectively, all higher than those in Example 7. This indicates that using a compound of dimethyl silicone oil, silicone, and polyether-modified polysiloxane as a defoamer, and controlling the mass ratio of dimethyl silicone oil, silicone, and polyether-modified polysiloxane to 4:3:3, can further improve the absorption efficiency of the waste gas absorption liquid for aromatic hydrocarbons, halogenated hydrocarbons, and alcohol-ketone-ester pollutants.

[0069] Based on the performance test data of the waste gas absorption liquid in Example 1 and Comparative Examples 1-3, it was found that adding surfactants, defoamers and dissolution promoters to the raw materials of the waste gas absorption liquid can improve the absorption efficiency of the waste gas absorption liquid for aromatic hydrocarbons, halogenated hydrocarbons and alcohol ketone esters to varying degrees.

[0070] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A water-based method for treating large volumes of low-concentration waste gas using a waste gas absorption liquid, characterized in that, The waste gas absorption liquid comprises the following raw materials in parts by weight: 100 parts surfactant, 5-20 parts defoamer, 100-200 parts dissolution promoter, and 5000 parts water. The solubility promoter is selected from one or more of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether; the defoamer is selected from one or more of butanol, dimethyl silicone oil, silicone, and polyether-modified polysiloxane. The surfactant is a compound of polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene fatty acid ester; the mass ratio of the polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene fatty acid ester is 4:2:

1. The polyoxyethylene alkyl ether is obtained through pretreatment, specifically as follows: glacial acetic acid is added to the polyoxyethylene alkyl ether, stirred at a rate of 300-400 r / min, heated to 50-55℃ and stirred until transparent, then 30% hydrogen peroxide is added dropwise at 1-2 mL / min. After the addition is complete, the temperature is raised to 70-75℃ and the reaction is maintained for 4-5 hours. The temperature is then lowered to 40℃, the pH is adjusted to 6.5-7.5, the mixture is distilled and washed, allowed to stand and separate into layers, the upper liquid is retained, and filtered to obtain the pretreated polyoxyethylene alkyl ether.

2. The waste gas absorption liquid for treating large-volume, low-concentration waste gas using a water-based method according to claim 1, characterized in that, The waste gas absorption liquid comprises the following raw materials in parts by weight: 100 parts surfactant, 15 parts defoamer, 150 parts dissolution promoter, and 5000 parts water.

3. The waste gas absorption liquid for treating large-volume, low-concentration waste gas using a water-based method according to claim 1, characterized in that, The solubility promoter is a compound of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether; the mass ratio of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether is 3:4:

3.

4. The waste gas absorption liquid for treating large-volume, low-concentration waste gas using a water-based method according to claim 3, characterized in that, The diethylene glycol monobutyl ether was obtained through pretreatment, specifically by adding diethylene glycol monobutyl ether, a 40% mass concentration dimethylamine aqueous solution, and dried γ-alumina to a high-pressure sealed reactor, mixing, stirring at a rate of 200-300 r / min, heating to 120-130℃ at a rate of 2℃ / min, maintaining the temperature for 6-8 h, distilling and purifying, and drying to obtain the pretreated diethylene glycol monobutyl ether.

5. The waste gas absorption liquid for treating large-volume, low-concentration waste gas using a water-based method according to claim 1, characterized in that, The defoamer is a compound of dimethyl silicone oil, silicone, and polyether-modified polysiloxane; the mass ratio of the dimethyl silicone oil, silicone, and polyether-modified polysiloxane is 4:3:

3.

6. A method for preparing a waste gas absorption liquid for treating large volumes of low-concentration waste gas using a water-based method as described in any one of claims 1-5, characterized in that, The process includes the following steps: mixing all the raw materials for the waste gas absorption liquid and stirring them evenly to obtain the waste gas absorption liquid.

7. A water-based treatment process for treating large volumes of low-concentration waste gas, characterized in that, This process includes the waste gas absorption liquid as described in any one of claims 1-5. The specific treatment process is as follows: The waste gas absorption liquid is prepared in an absorption liquid storage tank; the prepared absorption liquid is then loaded into the absorption tower through the inlet; organic waste gas is introduced into the absorption tower through a gas collection hood; the waste gas fully contacts the absorption liquid in the packing layer to complete the absorption process; the absorption conditions are: absorption temperature controlled at 20-40℃, pressure at atmospheric pressure, and maintaining a liquid-to-gas ratio of 1-8 m³ / s. 3 / m 3 The resulting absorbent containing waste gas was obtained.

8. The water-based treatment process for treating large volumes of low-concentration waste gas according to claim 7, characterized in that, The waste gas in the absorbent containing the waste gas is removed by membrane separation, heating distillation or adsorption, and the absorbent is recovered.

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