An emulsified absorbent for organic exhaust gas purification and a recovery process thereof

Abstract

The application discloses an emulsified absorbent for organic waste gas purification and a recycling process thereof, the emulsified absorbent comprises, in parts by weight, 3-10 parts of palm oil, 90-97 parts of water, 0.1-0.5 parts of a surfactant and 0.05-0.5 parts of a synergist. The synergist is beta-cyclodextrin or hydroxypropyl-beta-cyclodextrin, the surfactant is a compound of alkyl diphenyl ether disulfonate and polyether modified silicone oil, and the compound ratio is 1:1-5:1. The recycling process comprises: waste gas is contacted and absorbed with the absorbent in countercurrent, an enriched absorbent liquid is allowed to stand and is separated into an oil phase, an emulsified layer and a water phase; the oil phase is regenerated by low-temperature negative pressure flash evaporation, organic matters are recycled and regenerated palm oil is obtained; and the water phase is reused after being mixed with regenerated palm oil and the like. The application has high absorption efficiency, the absorbent can be recycled and regenerated, and the process is safe and environmentally friendly, and is suitable for resource treatment of various organic waste gases.

Description

Technical Field

[0001] This invention relates to the technical field of chemical environmental protection, specifically to an emulsified absorbent for purifying waste gas containing volatile organic compounds, and its supporting waste gas purification and recovery process. Background Technology

[0002] With industrial development, volatile organic compounds (VOCs) emitted from industries such as chemical, pharmaceutical, coating, and printing have become a significant source of air pollution. These gases often contain aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as dichloromethane and trichloroethylene; and alkanes such as n-hexane and cyclohexane. These VOCs not only pose serious threats to human health and the environment, but many of their components are also valuable chemical raw materials.

[0003] Currently, the mainstream technologies for treating low-to-medium concentration VOCs waste gas include adsorption, absorption, biological methods, and low-temperature plasma methods. Among these, absorption has attracted much attention due to its large processing capacity, continuous operation, relatively simple process flow, and potential for recovering useful components. The core of absorption lies in the design of high-performance absorbents.

[0004] In recent years, emulsion absorption technology has been proposed as an improvement strategy. By highly dispersing the organic absorbent phase in water to form an emulsion, it greatly increases the gas-liquid mass transfer surface area, theoretically significantly improving the absorption rate and efficiency. However, existing emulsion absorbents struggle to simultaneously achieve both emulsion stability and absorption efficiency. Overly stable emulsions are detrimental to organic matter recovery, while unstable emulsions affect the absorption process, failing to meet the demands of industrial development. Summary of the Invention

[0005] This application provides an emulsified absorbent for the purification of organic waste gas and its recovery process, in order to solve the problem mentioned in the background art that existing emulsified absorbents cannot simultaneously achieve both emulsion stability and absorption efficiency.

[0006] To address the aforementioned technical problems, in a first aspect, this application provides an emulsified absorbent for purifying organic waste gas, comprising, by weight, 3-10 parts palm oil, 90-97 parts water, 0.1-0.5 parts surfactant, and 0.05-0.5 parts synergist;

[0007] The synergist is β-cyclodextrin or hydroxypropyl-β-cyclodextrin, used to form inclusion complexes with organic molecules in the waste gas;

[0008] The surfactant is a compound of a gemini nonionic surfactant and a polyether-modified silicone oil. The gemini nonionic surfactant is an alkyl diphenyl ether disulfonate, and the mass ratio of the alkyl diphenyl ether disulfonate to the polyether-modified silicone oil is 1:1 to 5:1.

[0009] In one embodiment, the emulsifying absorbent is an oil-in-water (O / W) emulsion.

[0010] In one embodiment, the droplet size distribution of the emulsion ranges from 0.5 μm to 20 μm.

[0011] In one embodiment, the palm oil has an iodine value of 45gI2 / 100g to 55gI2 / 100g and a melting point of 30°C to 40°C.

[0012] Secondly, this application also provides a process for recovering the emulsified absorbent as described above, comprising the following steps:

[0013] S1: Cool and remove impurities from the waste gas containing organic matter to reduce the temperature of the waste gas to 0℃~40℃;

[0014] S2: Under normal pressure, the pretreated waste gas and the emulsified absorbent are brought into countercurrent contact in the absorption tower, the liquid-to-gas ratio is controlled to be 1L / m³~8L / m³, and the contact time is not less than 2s.

[0015] S3: The enriched absorbent liquid containing organic matter is transported to a settling separator and settling at 45℃~60℃ for 1h~3h to separate the enriched absorbent liquid into an upper oil phase, an intermediate emulsion layer and a lower aqueous phase containing organic matter.

[0016] S4: Collect the upper oil phase separated in step S3 and send it to a flash evaporator. Flash evaporation is carried out under the conditions of absolute pressure of 0.02MPa~0.05MPa and temperature of 60℃~80℃. The evaporated organic vapor is recovered after condensation. The remaining liquid in the flash evaporator is the recycled palm oil.

[0017] S5: Collect the lower aqueous phase separated in step S3, mix it with the regenerated palm oil and the supplemented surfactant and synergist to reform the emulsified absorbent, and return it to step S2 for recycling.

[0018] In one embodiment, in step S3, the intermediate emulsion layer is drawn out and treated by one or more of shearing, heating or adding a demulsifier. The oil phase separated after demulsification is incorporated into the flash evaporation device in step S4 for processing, and the separated aqueous phase is incorporated into step S5 for recycling.

[0019] In one embodiment, in step S5, the recycled palm oil is reused at a rate of 50% to 80% in the mixing step.

[0020] In one embodiment, the organic matter in the exhaust gas includes at least one of aromatic hydrocarbons, halogenated hydrocarbons, and alkanes.

[0021] In one embodiment, when the organic matter in the exhaust gas is mainly aromatics or alkanes, the amount of the synergist is 0.05 to 0.2 parts, and the mass ratio of the alkyl diphenyl ether disulfonate to the polyether modified silicone oil is 3:1 to 5:1.

[0022] When the organic matter in the exhaust gas is mainly halogenated hydrocarbons, the amount of the synergist is 0.2 to 0.5 parts, the mass ratio of the alkyl diphenyl ether disulfonate to the polyether modified silicone oil is 1:1 to 3:1, and the standing temperature in step S3 is 50°C to 60°C.

[0023] In one embodiment, when the organic matter in the exhaust gas includes halogenated hydrocarbons, the synergist is hydroxypropyl-β-cyclodextrin.

[0024] The aforementioned emulsified absorbent and its recovery process for purifying organic waste gas significantly improves absorption efficiency and has wide applicability by constructing a ternary synergistic absorption system of "palm oil dissolution - surfactant emulsification - cyclodextrin inclusion". Secondly, through the compound system of gemini surfactant and polyether modified silicone oil, a good balance is achieved between the kinetic stability of the emulsion during absorption and easy demulsification and separation during static settling after absorption. At a specific static settling temperature of 45-60℃, the absorbent can quickly and clearly achieve three-phase separation of oil-water-emulsion layer. In addition, the low-temperature negative pressure flash evaporation process is used to regenerate the oil-rich phase, which improves system safety while effectively preventing oxidation, polymerization and other deterioration reactions of palm oil, ensuring the quality of regenerated oil, realizing long-term, low-cost recycling of the absorbent, improving economic efficiency, and meeting the needs of modern industrial development. Detailed Implementation

[0025] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0026] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediary component present. Conversely, when a component is said to be "directly" connected to another component, there is no intermediary component.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] In the first aspect, this application provides an emulsified absorbent for the purification of organic waste gas, comprising, by weight, 3-10 parts palm oil, 90-97 parts water, 0.1-0.5 parts surfactant, and 0.05-0.5 parts synergist; wherein, palm oil serves as the basic absorption medium, with an iodine value of 45gI2 / 100g-55gI2 / 100g and a melting point of 30℃-40℃. Within this range, palm oil possesses suitable oxidative stability and phase transition temperature, enabling it to remain liquid at the absorption temperature to ensure good fluidity, maintain stability at the static temperature, and achieve efficient stratification by utilizing the density difference between it and water. Furthermore, it exhibits good similar-phase-soluble absorption of non-polar or weakly polar alkanes and aromatics.

[0029] Furthermore, the surfactant is a compound of a gemini nonionic surfactant and a polyether-modified silicone oil. The gemini nonionic surfactant is an alkyl diphenyl ether disulfonate, and the mass ratio of the alkyl diphenyl ether disulfonate to the polyether-modified silicone oil is 1:1 to 5:1. The gemini surfactant possesses extremely high surface activity, significantly reducing the oil-water interfacial tension and forming a dense interfacial film, thus improving the stability of the emulsion during absorption. The polyether-modified silicone oil further improves interfacial fluidity and aids in the emulsification of polar organic compounds. This compounding of the alkyl diphenyl ether disulfonate with the polyether-modified silicone oil lays the foundation for balancing emulsion stability and subsequent demulsification and separation.

[0030] Furthermore, the synergist is β-cyclodextrin or hydroxypropyl-β-cyclodextrin, which is used to form inclusion complexes with organic molecules in the waste gas to enhance absorption capacity. Among them, β-cyclodextrin has excellent inclusion capacity for aromatic hydrocarbons such as benzene series due to its cavity size, while hydroxypropyl-β-cyclodextrin has significantly improved water solubility due to the introduction of hydroxypropyl substituents, and the microenvironment of the cavity is changed, showing stronger affinity and solubilization effect for more polar halogenated hydrocarbon organic compounds.

[0031] In this application, through the specific ratio and synergy of the above components, the prepared emulsion absorbent is an oil-in-water (O / W) emulsion. The oil-in-water (O / W) emulsion has a continuous aqueous phase, which can avoid the direct volatilization loss of the organic absorbent phase. Moreover, the droplet size distribution range of the emulsion is 0.5μm to 20μm, which ensures that the emulsion has good stability to complete the absorption process, and is not too stable to make it difficult to demulsify and separate in subsequent steps.

[0032] Secondly, this application also provides a recovery process for the emulsifying absorbent, including the following steps:

[0033] S1: Cool and remove impurities from the waste gas containing organic matter to reduce the temperature of the waste gas to 0℃~40℃;

[0034] S2: Under normal pressure, the pretreated waste gas and the emulsion absorbent are brought into countercurrent contact in the absorption tower, the liquid-to-gas ratio is controlled at 1L / m³~8L / m³, and the contact time is not less than 2s. During this process, the organic components in the waste gas are efficiently absorbed by the emulsion droplets, and the temperature is controlled at 10℃~30℃ during the absorption process to balance the absorption efficiency and energy consumption.

[0035] S3: The enriched absorbent liquid containing organic matter is transported to a settling separator and settling at 45℃~60℃ for 1h~3h to separate the enriched absorbent liquid into an upper oil phase, an intermediate emulsion layer and a lower aqueous phase containing organic matter.

[0036] S4: Collect the upper oil phase separated in step S3 and send it to a flash evaporator. Flash evaporation is carried out under the conditions of absolute pressure of 0.02MPa~0.05MPa and temperature of 60℃~80℃. The evaporated organic vapor is recovered after condensation. The liquid remaining in the flash evaporator is the recycled palm oil. Flash evaporation is carried out under negative pressure to ensure the safety of the system and prevent air from entering and forming an explosive mixture.

[0037] S5: Collect the lower aqueous phase separated in step S3, mix it with recycled palm oil and supplemented surfactants and synergists to reform the emulsified absorbent, and return it to step S2 for recycling; wherein, the recycling ratio of recycled palm oil in the mixing is 50% to 80%. This design reduces the consumption of raw materials and the discharge of waste liquid, and improves economic and environmental benefits.

[0038] Furthermore, in step S3, the separated intermediate emulsion layer can be extracted separately and treated by applying shear, heating or adding a demulsifier to promote the demulsification of the intermediate emulsion layer. The oil phase separated after demulsification is incorporated into step S4 for processing, and the separated aqueous phase is incorporated into step S5 for recycling, thereby improving the total recovery rate of organic matter.

[0039] Furthermore, the organic matter in the waste gas includes at least one of aromatic hydrocarbons, halogenated hydrocarbons, and alkanes. Specifically, when the organic matter in the waste gas is mainly aromatic hydrocarbons or alkanes, the amount of synergist is 0.05 to 0.2 parts, and the mass ratio of alkyl diphenyl ether disulfonate to polyether modified silicone oil is 3:1 to 5:1. These process parameters mainly focus on maintaining the stable absorption of non-polar substances by the emulsion.

[0040] When the organic matter in the exhaust gas is mainly halogenated hydrocarbons, the amount of synergist used is 0.2 to 0.5 parts, preferably hydroxypropyl-β-cyclodextrin, to enhance the encapsulation ability; the mass ratio of alkyl diphenyl ether disulfonate to polyether modified silicone oil is 1:1 to 3:1, which is used to enhance the interfacial activity for emulsifying polar organic matter; at the same time, the standing temperature in step S3 is controlled at 50℃ to 60℃ to promote oil-water separation.

[0041] Example 1: Performance and Recycling Process Verification of Emulsifying Absorbents for Aromatic Hydrocarbon Waste Gases (Part 1)

[0042] Weigh 50.00g of palm oil with an iodine value of 50gI2 / 100g and a melting point of 35℃, 1.00g of surfactant (0.75g of sodium dodecyl diphenyl ether disulfonate and 0.25g of ethylene oxide (EO)-terminated hydrophilic polyether modified silicone oil), 0.50g of β-cyclodextrin, and 948.50g of deionized water, place them in a high-speed shear emulsifier, and emulsify at 8000rpm for 15min at room temperature to obtain a uniform and stable oil-in-water (O / W) type emulsifying absorbent.

[0043] According to laser particle size analyzer, the D50 of the emulsion absorbent droplets is 5.2 μm, the D90 is 15.8 μm, and the particle size distribution range is 0.8 μm to 18.5 μm.

[0044] The emulsified absorbent prepared above was used to conduct toluene waste gas purification tests in a laboratory packed absorption tower:

[0045] The simulated waste gas was a mixture of high-purity nitrogen as carrier gas and toluene concentration of (1000±50) mg / m³. Under normal pressure and 25℃ conditions, the waste gas was introduced into the bottom of the tower at a gas velocity of 0.5 m / s, while the emulsified absorbent was sprayed from the top of the tower. The liquid-to-gas ratio was controlled at 4 L / m³, and the gas phase residence time was approximately 3 seconds. After the system ran stably for 30 minutes, the inlet and outlet toluene concentrations were measured six times consecutively using an online gas chromatograph (GC-FID), and the average value was taken. The average inlet toluene concentration was measured to be 1020 mg / m³, and the average outlet toluene concentration was 120 mg / m³. The absorption efficiency of toluene was calculated.

[0046] Absorption efficiency η = [(C_in - C_out) / C_in] × 100%

[0047] =[(1020mg / m³-120mg / m³) / 1020mg / m³×100%=88.2%

[0048] The enriched absorbent was collected and transferred to a static separator and allowed to stand at 45°C for 2 hours to achieve clear three-phase stratification: an upper oil phase, an intermediate emulsion layer, and a lower aqueous phase. The upper oil phase and the lower aqueous phase were collected separately for later use. The intermediate emulsion layer was collected separately and demulsified by stirring at 60°C and 200 rpm for 5 minutes. The separated oil phase was incorporated into the subsequent flash evaporation feedstock, and the aqueous phase was incorporated into the lower aqueous phase for reuse.

[0049] Accurately weigh 50.00g from the upper oil phase obtained by static separation and place it in a flash evaporator. Flash evaporate for 30min under an absolute pressure of 0.03MPa and a temperature of 70℃. The distilled toluene vapor is recovered by condensation. After flash evaporation, all the residual liquid in the flash evaporator is quantitatively transferred to a pre-weighed clean container. The total mass of the container and liquid is 130.835g, of which the container mass is 86.632g. Therefore, the mass of the regenerated palm oil is m = 130.835g - 86.632g = 45.203g.

[0050] The acid values ​​of palm oil before and after regeneration were tested according to GB 5009.229-2016 "National Food Safety Standard - Determination of Acid Value in Food". The acid value of palm oil before regeneration was 0.2 mg KOH / g, and the acid value of palm oil after regeneration was 0.3 mg KOH / g. This indicates that the absorption and regeneration process of this application is under mild conditions, which effectively avoids the thermal oxidation and hydrolysis of palm oil, ensures the stability of the absorbent, and provides a basis for the long-term recycling of palm oil.

[0051] The lower aqueous phase obtained after settling was replenished with water to its original volume. Then, 30% by mass of recycled palm oil (70% reuse ratio), supplementary surfactants calculated according to the initial formulation ratio, and β-cyclodextrin were mixed to prepare a circulating batch absorbent using the same emulsification process. A second round of toluene waste gas absorption tests was conducted under identical conditions, and the toluene absorption efficiency was measured to be 87.5%.

[0052] This embodiment illustrates that the formula and process achieve high purification efficiency of toluene waste gas, good separation and high-quality regeneration of the absorbent, and stable performance of the regenerated absorbent, thus realizing a closed-loop operation of efficient purification and resource recovery.

[0053] Example 2: Performance Verification and Recycling Process Validation of Emulsifying Absorbents for Aromatic Hydrocarbon Waste Gases (Part Two)

[0054] The difference from Example 1 is that the mass ratio of sodium dodecyl diphenyl ether disulfonate to ethylene oxide (EO)-terminated hydrophilic polyether modified silicone oil is 2:1.

[0055] According to laser particle size analyzer, the D50 of the emulsion absorbent droplets is 5.0 μm, the D90 is 15.5 μm, and the particle size distribution range is 0.8 μm to 17.5 μm.

[0056] Using the emulsified absorbent prepared above, absorption tests were conducted under the exact same conditions as in Example 1. After the system stabilized, the average inlet toluene concentration was measured to be 1018 mg / m³, and the average outlet toluene concentration was 128 mg / m³. The absorption efficiency of toluene was calculated.

[0057] Absorption efficiency η = [(C_in - C_out) / C_in] × 100%

[0058] =[(1018mg / m³-118mg / m³) / 1018mg / m³×100%=87.4%

[0059] The enriched absorbent was collected and transferred to a static separator and allowed to stand at 45°C for 2 hours to achieve clear three-phase stratification: an upper oil phase, an intermediate emulsion layer, and a lower aqueous phase. The upper oil phase and the lower aqueous phase were collected separately for later use. The intermediate emulsion layer was collected separately and demulsified by stirring at 60°C and 200 rpm for 5 minutes. The separated oil phase was incorporated into the subsequent flash evaporation feedstock, and the aqueous phase was incorporated into the lower aqueous phase for reuse.

[0060] Accurately weigh 50.00g from the upper oil phase obtained by static separation and place it in a flash evaporator. Flash evaporate for 30min under an absolute pressure of 0.03MPa and a temperature of 70℃. The distilled toluene vapor is recovered by condensation. After flash evaporation, all the residual liquid in the flash evaporator is quantitatively transferred to a pre-weighed clean container. The total mass of the container and liquid is 131.624g, of which the container mass is 86.630g. Therefore, the mass of the regenerated palm oil is m = 131.624g - 86.630g = 44.994g.

[0061] The acid value of palm oil before and after regeneration was tested according to the method in GB 5009.229-2016 "National Food Safety Standard - Determination of Acid Value in Food". The acid value of palm oil before regeneration was 0.3 mg KOH / g, and the acid value of palm oil after regeneration was 0.4 mg KOH / g. The data show that the regeneration process of this invention can still effectively protect the palm oil matrix and prevent its thermal oxidation and deterioration even with an absorption system using a 2:1 surfactant compound ratio.

[0062] The lower aqueous phase obtained after settling was replenished with water to its original volume. Then, 30% by mass of recycled palm oil (70% reuse ratio), supplementary surfactants calculated according to the initial formulation ratio, and β-cyclodextrin were mixed to prepare a circulating batch absorbent using the same emulsification process. A second round of toluene waste gas absorption tests was conducted under identical conditions, and the toluene absorption efficiency was measured to be 86.9%.

[0063] This embodiment demonstrates that an emulsified absorbent with a 2:1 ratio of sodium dodecyl diphenyl ether disulfonate and ethylene oxide (EO)-terminated hydrophilic polyether-modified silicone oil can still stably achieve efficient absorption, gentle regeneration, and good recycling.

[0064] Example 3: Performance and Recycling Process Verification of Emulsifying Absorbents for Halogenated Hydrocarbon Waste Gases

[0065] Weigh 50.00g of palm oil with an iodine value of 50gI2 / 100g and a melting point of 35℃, 1.00g of surfactant (0.75g of sodium dodecyl diphenyl ether disulfonate and 0.25g of ethylene oxide (EO)-terminated hydrophilic polyether modified silicone oil), 0.50g of β-cyclodextrin, and 948.50g of deionized water, place them in a high-speed shear emulsifier, and emulsify at 8000rpm for 15min at room temperature to obtain a uniform and stable oil-in-water (O / W) type emulsifying absorbent.

[0066] According to laser particle size analyzer, the D50 of the emulsion absorbent droplets is 5.2 μm, the D90 is 15.8 μm, and the particle size distribution range is 0.8 μm to 18.5 μm.

[0067] Using the emulsified absorbent prepared above, dichloromethane waste gas purification tests were conducted in a laboratory packed absorption tower.

[0068] The simulated waste gas was a mixture of high-purity nitrogen as carrier gas and dichloromethane concentration of (800±40) mg / m³. Under normal pressure and 25℃ conditions, the waste gas was introduced into the bottom of the tower at a gas velocity of 0.5 m / s, while the emulsified absorbent was sprayed from the top of the tower. The liquid-to-gas ratio was controlled at 4 L / m³, and the gas phase residence time was approximately 3 seconds. After the system ran stably for 30 minutes, the inlet and outlet dichloromethane concentrations were measured six times consecutively using an online gas chromatograph (GC-FID), and the average value was taken. The average inlet concentration of dichloromethane was measured to be 820 mg / m³, and the average outlet concentration was 105 mg / m³. The absorption efficiency of dichloromethane was calculated.

[0069] Absorption efficiency η = [(C_in - C_out) / C_in] × 100%

[0070] =[(820mg / m³-105mg / m³) / 820mg / m³×100%=87.2%

[0071] The enriched absorbent was collected and transferred to a static separator and allowed to stand at 45°C for 2 hours to achieve clear three-phase stratification: an upper oil phase, a middle emulsion layer, and a lower aqueous phase, although the middle emulsion layer was more distinct. The upper oil phase and the lower aqueous phase were collected separately for later use. The middle emulsion layer was collected separately and demulsified by stirring at 60°C and 200 rpm for 5 minutes. The separated oil phase was incorporated into the subsequent flash evaporation feedstock, and the aqueous phase was incorporated into the lower aqueous phase for reuse.

[0072] Accurately weigh 50.00g from the upper oil phase obtained by static separation and place it in a flash evaporator. Flash evaporate for 30min under an absolute pressure of 0.03MPa and a temperature of 70℃. The dichloromethane vapor distilled off is recovered by condensation. After flash evaporation, all the residual liquid in the flash evaporator is quantitatively transferred to a pre-weighed clean container. The total mass of the container and liquid is 131.876g, of which the container mass is 86.631g. Therefore, the mass of the regenerated palm oil is m = 131.876g - 86.631g = 45.245g.

[0073] The acid value of palm oil before and after regeneration was tested according to the method in GB 5009.229-2016 "National Food Safety Standard - Determination of Acid Value in Food". The acid value of palm oil before regeneration was 0.4 mg KOH / g, and the acid value of palm oil after regeneration was 0.5 mg KOH / g. This shows that the formula in this embodiment can still achieve good absorption efficiency when treating halogenated hydrocarbons.

[0074] The lower aqueous phase obtained after settling was replenished with water to its original volume. Then, 30% by mass of recycled palm oil (70% reuse ratio), supplementary surfactants calculated according to the initial formulation ratio, and β-cyclodextrin were mixed and used to prepare a circulating batch absorbent using the same emulsification process. A second round of dichloromethane absorption tests was conducted under identical conditions, and the dichloromethane absorption efficiency was measured to be 86.8%.

[0075] Example 4: Optimal formulation and process verification for halogenated hydrocarbon waste gas

[0076] Weigh 50.00g of palm oil with an iodine value of 50gI2 / 100g and a melting point of 36℃, 1.00g of surfactant (0.50g of sodium dodecyl diphenyl ether disulfonate and 0.50g of ethylene oxide (EO)-terminated hydrophilic polyether modified silicone oil), 0.80g of hydroxypropyl-β-cyclodextrin, and 918.20g of water, place them in a high-speed shear emulsifier, and emulsify at 8000rpm for 15min at room temperature to obtain a uniform and stable oil-in-water (O / W) type emulsifying absorbent.

[0077] According to laser particle size analyzer, the D50 of the emulsion absorbent droplets is 4.8 μm, the D90 is 15.3 μm, and the particle size distribution ranges from 0.7 μm to 16.2 μm.

[0078] Using the emulsified absorbent prepared above, dichloromethane waste gas purification tests were conducted in a laboratory packed absorption tower.

[0079] The simulated waste gas was a mixture of high-purity nitrogen as carrier gas and dichloromethane concentration of (800±40) mg / m³. Under normal pressure and 25℃ conditions, the waste gas was introduced into the bottom of the tower at a gas velocity of 0.5 m / s, while the emulsified absorbent was sprayed from the top of the tower. The liquid-to-gas ratio was controlled at 4 L / m³, and the gas phase residence time was approximately 3 seconds. After the system ran stably for 30 minutes, the inlet and outlet dichloromethane concentrations were measured six times consecutively using an online gas chromatograph (GC-FID), and the average value was taken. The average inlet concentration of dichloromethane was measured to be 815 mg / m³, and the average outlet concentration was 85 mg / m³. The absorption efficiency of dichloromethane was calculated.

[0080] Absorption efficiency η = [(C_in - C_out) / C_in] × 100%

[0081] =[(815mg / m³-85mg / m³) / 815mg / m³×100%=89.6%

[0082] The enriched absorbent was collected and transferred to a settling separator and settling at 55°C for 2 hours. After settling, a clear three-phase stratification was observed, namely an upper oil phase, an intermediate emulsion layer, and a lower aqueous phase. The upper oil phase and the lower aqueous phase were collected separately for later use. The intermediate emulsion layer was collected separately and demulsified by stirring at 60°C and 200 rpm for 5 minutes. The separated oil phase was incorporated into the subsequent flash evaporation feedstock, and the aqueous phase was incorporated into the lower aqueous phase for reuse.

[0083] Accurately weigh 50.00g from the upper oil phase obtained by static separation and place it in a flash evaporator. Flash evaporate for 30min under an absolute pressure of 0.03MPa and a temperature of 70℃. The dichloromethane vapor produced is recovered by condensation. After flash evaporation, all the residual liquid in the flash evaporator is quantitatively transferred to a pre-weighed clean container. The total mass is 131.132g, of which the container mass is 86.632g. Therefore, the mass of the regenerated palm oil is m = 131.132g - 86.632g = 44.500g.

[0084] According to the method of GB 5009.229-2016 "National Food Safety Standard - Determination of Acid Value in Food", the acid value of palm oil before and after regeneration was tested. The acid value of palm oil before regeneration was 0.3 mgKOH / g, and the acid value of palm oil after regeneration was 0.4 mgKOH / g, indicating that the regeneration conditions of this application are relatively mild and effectively protect the absorbent matrix.

[0085] The lower aqueous phase obtained after settling was replenished with water to its original volume. 30% by mass of recycled palm oil (70% reuse ratio), supplementary surfactant calculated according to the initial formulation ratio, and hydroxypropyl-β-cyclodextrin were mixed and used to prepare a circulating batch absorbent using the same emulsification process. A second round of dichloromethane absorption testing was conducted using this circulating batch absorbent under the exact same conditions as the first round, and the dichloromethane absorption efficiency was measured to be 88.9%. This demonstrates that the optimized formulation and process of this embodiment achieves better oil-water separation, and the absorption efficiency for dichlorotoluene is significantly higher than in Example 3.

[0086] Example 5: Verification of the purification performance of high palm oil content formulation on trichloroethylene waste gas

[0087] Weigh 100.00g of palm oil with an iodine value of 50gI2 / 100g and a melting point of 35℃, 1.20g of surfactant (1.00g of sodium dodecyl diphenyl ether disulfonate and 0.20g of ethylene oxide (EO)-terminated hydrophilic polyether modified silicone oil), 1.00g of β-cyclodextrin, and 897.80g of deionized water, place them in a high-speed shear emulsifier, and emulsify at 8000rpm for 15min at room temperature to obtain a uniform and stable oil-in-water (O / W) type emulsifying absorbent.

[0088] According to laser particle size analyzer, the D50 of the emulsion absorbent droplets is 6.5 μm, the D90 is 21.9 μm, and the particle size distribution ranges from 1.0 μm to 25.0 μm.

[0089] Using the emulsified absorbent prepared above, trichloroethylene waste gas purification tests were conducted in a laboratory packed absorption tower:

[0090] The simulated waste gas was a mixture of high-purity nitrogen as carrier gas and trichloroethylene concentration of (1500±75) mg / m³. Under normal pressure and 25℃ conditions, the waste gas was introduced into the bottom of the tower at a velocity of 0.5 m / s, while the emulsified absorbent was sprayed from the top of the tower, controlling the liquid-to-gas ratio at 6 L / m³. After the system ran stably for 30 minutes, the inlet and outlet trichloroethylene concentrations were measured six times consecutively using an online gas chromatograph (GC-FID), and the average value was taken. The measured average inlet concentration of trichloroethylene was 1525 mg / m³, and the average outlet concentration was 205 mg / m³. The absorption efficiency of trichloroethylene was calculated.

[0091] Absorption efficiency η = [(C_in - C_out) / C_in] × 100%

[0092] =[(1525mg / m³-205mg / m³) / 1525mg / m³×100%=86.5%

[0093] The enriched absorbent was collected and transferred to a settling separator and settling at 50°C for 3 hours. After settling, three-phase stratification was still achieved, but the volume ratio of the upper oil phase was significantly higher than that in Example 1, which was in line with expectations.

[0094] 60.00 g of the upper oil phase obtained from static separation was accurately weighed and placed in a flash evaporator. Due to the high boiling point of trichloroethylene (87.2℃), flash evaporation was carried out for 40 min at an absolute pressure of 0.02 MPa and a temperature of 75℃ to ensure regeneration efficiency. After flash evaporation, the regenerated palm oil was collected and weighed according to the method in Example 1. The recovered mass was calculated to be 53.2 g, and the acid value of the regenerated palm oil was measured to be 0.5 mg KOH / g. The acid value increased slightly but remained at a very low level, indicating that the high oil phase formulation with a palm oil content of 10 parts in this example still achieved good absorption efficiency for trichloroethylene at a relatively high inlet concentration. This further demonstrates that the formulation of this application has good adaptability to high-concentration and difficult-to-treat waste gases.

[0095] The lower aqueous phase obtained after settling was replenished with water to its original volume. Then, 30% by mass of regenerated palm oil (70% reuse ratio), and supplementary surfactants and synergists calculated according to the initial formula ratio were mixed. A circulating batch absorbent was prepared using the same emulsification process. Using this circulating batch absorbent, a second round of dichloromethane waste gas absorption tests was conducted under the exact same conditions as the first round. The trichloroethylene absorption efficiency was measured to be 85.8%. This demonstrates that the absorbent can still be stably regenerated using the process of this embodiment.

[0096] Example 6: Verification of High-Temperature Absorption Conditions

[0097] The absorbent was prepared using the formulation and emulsification process of Example 1.

[0098] The simulated waste gas was a mixture of high-purity nitrogen as carrier gas and toluene concentration of (1000±50) mg / m³. Under normal pressure and 40℃ conditions, the waste gas was introduced into the bottom of the tower at a velocity of 0.5 m / s, while the emulsified absorbent was sprayed from the top of the tower. The liquid-to-gas ratio was controlled at 4 L / m³, and the gas phase residence time was approximately 3 seconds. After the system ran stably for 30 minutes, the inlet and outlet toluene concentrations were measured six times consecutively using an online gas chromatograph (GC-FID), and the average value was taken. The average inlet toluene concentration was measured to be 1015 mg / m³, and the average outlet toluene concentration was 132 mg / m³. The absorption efficiency of toluene was calculated.

[0099] Absorption efficiency η = [(C_in - C_out) / C_in] × 100%

[0100] =[(1015mg / m³-132mg / m³) / 1015mg / m³×100%=87.0%

[0101] Accurately weigh 50.00g from the upper oil phase obtained by static separation and place it in a flash evaporator. Flash evaporate for 30min under an absolute pressure of 0.03MPa and a temperature of 70℃. The distilled toluene vapor is recovered by condensation. After flash evaporation, collect and weigh the regenerated palm oil according to the method in Example 1. The recovered mass is calculated to be 45.195g, and the acid value of the regenerated palm oil is measured to be 0.4mgKOH / g.

[0102] The lower aqueous phase obtained by settling was replenished with water to the original volume, and 30% by mass of recycled palm oil with a 70% reuse ratio, supplementary surfactant and β-cyclodextrin calculated according to the initial formula ratio were mixed and re-emulsified to prepare a circulating batch absorbent. The second round of absorption test was carried out under the same 40℃ conditions, and the toluene absorption efficiency was measured to be 86.5%.

[0103] The results show that even at 40°C, the initial absorption efficiency of toluene using the formula and process of this invention is still as high as 87.0%, and the recycling efficiency of the absorbent after regeneration remains at 86.5%. This fully demonstrates that the process of this invention has good adaptability to operating temperature fluctuations, can operate efficiently without a complex temperature control system, and ensures the treatment effect of toluene waste gas.

[0104] Example 7: Optimization Experiment of Synergist Dosage

[0105] With a fixed amount of 5 parts palm oil, 94.9 parts water, and 0.1 parts surfactant (sodium dodecyl diphenyl ether disulfonate: ethylene oxide (EO)-terminated hydrophilic polyether modified silicone oil = 3:1), 0 parts, 0.02 parts, 0.05 parts, 0.10 parts, 0.20 parts, 0.50 parts, and 1.00 parts of hydroxypropyl-β-cyclodextrin were weighed out, and deionized water was added to bring the total weight to 1000 g. Seven samples (5-1 to 5-7) were prepared according to the process in Example 1. Toluene waste gas was treated under the conditions of Example 1, and its absorption efficiency, emulsion stability (after standing for 24 hours), and flowability were tested. The results are shown in Table 1.

[0106] Table 1

[0107]

[0108] As shown in Table 1, when the amount of synergist is between 0.05 and 0.5 parts, the absorption efficiency increases significantly from 88.8% to 91.2%, while maintaining good stability and fluidity of the emulsion. When the amount of synergist is less than 0.05 parts, the synergistic effect is insufficient. When the amount of synergist is greater than 0.5 parts, the absorption efficiency no longer increases, and the emulsion becomes excessively viscous, its fluidity deteriorates, and even separation becomes difficult.

[0109] Comparative Example 1

[0110] The difference from Example 1 is that no synergist is added, and the amount of synergist is replaced with water to prepare an emulsified absorbent.

[0111] Laser particle size analyzer measurements showed that the D50 of the emulsified absorbent droplets was 6.5 μm, the D90 was 20.1 μm, and the particle size distribution ranged from 1.0 μm to 25.0 μm. This indicates that the particle size of Comparative Example 1 is larger than that of Example 1, demonstrating that the synergist β-cyclodextrin has a certain auxiliary emulsifying and droplet-stabilizing effect.

[0112] Absorption tests were conducted under the exact same conditions as in Example 1. After the system stabilized, the average toluene concentration at the outlet was measured to be 184 mg / m³. The absorption efficiency of toluene was calculated.

[0113] Absorption efficiency η = [(C_in - C_out) / C_in] × 100%

[0114] =[(1020mg / m³-184mg / m³) / 1020mg / m³×100%=82.0%

[0115] In summary, after removing the synergist β-cyclodextrin, the toluene absorption efficiency of Comparative Example 1 was significantly lower than that of Example 1, indicating that the addition of the synergist β-cyclodextrin is beneficial to improving the absorption efficiency.

[0116] Comparative Example 2

[0117] The difference from Example 1 is that the synergist β-cyclodextrin is replaced with an equal amount of dextrin to prepare an emulsifying absorbent.

[0118] The D50 and D90 of the emulsifying absorbent droplets were measured by a laser particle size analyzer to be 6.5 μm and 20.0 μm, respectively, indicating that dextrin has similar thickening and limited emulsifying effects as β-cyclodextrin.

[0119] Absorption tests were conducted under the exact same conditions as in Example 1. After the system stabilized, the average toluene concentration at the outlet was measured to be 180 mg / m³. The absorption efficiency of toluene was calculated.

[0120] Absorption efficiency η = [(C_in - C_out) / C_in] × 100%

[0121] =[(1020mg / m³-180mg / m³) / 1020mg / m³×100%=82.4%

[0122] In summary, the toluene absorption efficiency of Comparative Example 2 is significantly lower than that of Example 1, indicating that selecting β-cyclodextrin as a synergist results in better absorption efficiency of toluene waste gas.

[0123] Comparative Example 3

[0124] A batch of emulsified absorbent was prepared using the exact same initial formulation and emulsification process as in Example 1. This batch of absorbent was divided into two equal parts and used in the following two sets of parallel cyclic experiments:

[0125] Group A: After each absorption test, the oil-rich phase is regenerated using the process described in this application, namely flash evaporation at an absolute pressure of 0.03 MPa and a temperature of 70°C.

[0126] Group B: After each absorption test, the regeneration of the oil-rich phase was carried out using a conventional high-temperature distillation process, namely distillation at atmospheric pressure (0.101 MPa) and temperature of 120°C.

[0127] Cyclic experimental method:

[0128] First round of absorption: Both groups used the initially prepared absorbent and conducted absorption tests under the exact same conditions as in Example 1 (toluene concentration 1000 mg / m³, 25°C, liquid-to-gas ratio 4 L / m³), and recorded the absorption efficiency.

[0129] Regeneration and Reuse: After absorption testing, the enriched absorbent was collected and the upper oil phase was regenerated according to the process conditions of each group (Group A: 0.03 MPa / 70℃ flash evaporation; Group B: atmospheric pressure / 120℃ distillation). After regeneration, the regenerated palm oil was mixed with replenished water, surfactant, and synergist at a reuse ratio of 70%, and re-emulsified to prepare the absorbent for the next cycle, following the same method as in Example 1.

[0130] Subsequent cycles: Steps 1 and 2 were repeated for a total of 5 complete "absorption-regeneration-reuse" cycles. Fresh simulated toluene waste gas was treated with freshly prepared absorbent in each cycle for each group, and the absorption efficiency was recorded each time; simultaneously, the acid value change of the regenerated palm oil in group B after each cycle was monitored. The experimental results are shown in Table 2:

[0131] Table 2

[0132]

[0133] As shown in Table 2, using the low-temperature negative pressure flash evaporation process of this invention, the absorption efficiency remains as high as 86.5% after the absorbent is recycled 5 times, with a low performance decay rate. Moreover, the regenerated oleic acid value of group A remains at a low level of 0.2 mg KOH / g to 0.4 mg KOH / g. The results indicate that the process of this application has good cycle stability. In contrast, the efficiency of the conventional high-temperature distillation process drops sharply in the third cycle, and the regenerated oleic acid value rises sharply, resulting in deterioration in appearance, which cannot meet the requirements for long-term cyclic use.

[0134] In summary, this application, through a specific emulsified absorbent formulation and a matching recovery process, particularly the synergistic effect of synergists, composite surfactants, low-temperature negative pressure flash regeneration, and differentiated adjustment strategies, not only achieves efficient, stable, and safe recovery of various VOCs, but also realizes the recycling of absorbents, thereby improving economic efficiency.

[0135] The options described in the above method embodiments are also applicable to this embodiment, and will not be detailed here. The remaining content of this application's embodiments can be found in the above method embodiments, and will not be repeated in this embodiment.

[0136] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0137] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An emulsified absorbent for purifying organic waste gas, characterized in that, By weight, it includes 3-10 parts palm oil, 90-97 parts water, 0.1-0.5 parts surfactant, and 0.05-0.5 parts synergist; The synergist is β-cyclodextrin or hydroxypropyl-β-cyclodextrin, used to form inclusion complexes with organic molecules in the waste gas; The surfactant is a compound of alkyl diphenyl ether disulfonate and polyether modified silicone oil, and the mass ratio of the compound of alkyl diphenyl ether disulfonate and polyether modified silicone oil is 3:1 to 5:

1. The recovery process of the emulsified absorbent includes the following steps: S1: Cool and remove impurities from the waste gas containing organic matter to reduce the temperature of the waste gas to 0℃~40℃; S2: Under normal pressure, the pretreated waste gas and the emulsified absorbent are brought into countercurrent contact in the absorption tower, the liquid-to-gas ratio is controlled to be 1L / m³~8L / m³, and the contact time is not less than 2s. S3: The enriched absorbent liquid containing organic matter is transported to a settling separator and settling at 45℃~60℃ for 1h~3h to separate the enriched absorbent liquid into an upper oil phase, an intermediate emulsion layer and a lower aqueous phase containing organic matter. S4: Collect the upper oil phase separated in step S3 and send it to a flash evaporator. Flash evaporation is carried out under the conditions of absolute pressure of 0.02MPa~0.05MPa and temperature of 60℃~80℃. The evaporated organic vapor is recovered after condensation. The remaining liquid in the flash evaporator is the recycled palm oil. S5: Collect the lower aqueous phase separated in step S3, mix it with the regenerated palm oil and the supplemented surfactant and synergist to reform the emulsified absorbent, and return it to step S2 for recycling.

2. The emulsifying absorbent according to claim 1, characterized in that, The emulsifying absorbent is an oil-in-water (O / W) emulsion.

3. The emulsifying absorbent according to claim 2, characterized in that, The droplet size distribution of the emulsion ranges from 0.5 μm to 20 μm.

4. The emulsifying absorbent according to claim 1, characterized in that, The palm oil has an iodine value of 45gI2 / 100g to 55gI2 / 100g and a melting point of 30℃ to 40℃.

5. A process for recovering the emulsified absorbent as described in any one of claims 1-4, characterized in that, Includes the following steps: S1: Cool and remove impurities from the waste gas containing organic matter to reduce the temperature of the waste gas to 0℃~40℃; S2: Under normal pressure, the pretreated waste gas and the emulsified absorbent are brought into countercurrent contact in the absorption tower, the liquid-to-gas ratio is controlled to be 1L / m³~8L / m³, and the contact time is not less than 2s. S3: The enriched absorbent liquid containing organic matter is transported to a settling separator and settling at 45℃~60℃ for 1h~3h to separate the enriched absorbent liquid into an upper oil phase, an intermediate emulsion layer and a lower aqueous phase containing organic matter. S4: Collect the upper oil phase separated in step S3 and send it to a flash evaporator. Flash evaporation is carried out under the conditions of absolute pressure of 0.02MPa~0.05MPa and temperature of 60℃~80℃. The evaporated organic vapor is recovered after condensation. The remaining liquid in the flash evaporator is the recycled palm oil. S5: Collect the lower aqueous phase separated in step S3, mix it with the regenerated palm oil and the supplemented surfactant and synergist to reform the emulsified absorbent, and return it to step S2 for recycling.

6. The process for recovering the emulsified absorbent according to claim 5, characterized in that, In step S3, the intermediate emulsion layer is extracted and treated by one or more of the following methods: applying shear, heating, or adding a demulsifier. The oil phase separated after demulsification is incorporated into the flash evaporation device in step S4 for processing, and the separated aqueous phase is incorporated into step S5 for recycling.

7. The process for recovering the emulsifying absorbent according to claim 5, characterized in that, In step S5, the recycled palm oil is reused at a rate of 50% to 80% in the mixing step.

8. The process for recovering the emulsifying absorbent according to claim 5, characterized in that, The organic matter in the exhaust gas includes at least one of aromatic hydrocarbons, halogenated hydrocarbons, and alkanes; When the organic matter in the exhaust gas is mainly aromatic hydrocarbons or alkanes, the amount of the synergist is 0.05 to 0.2 parts, and the mass ratio of the alkyl diphenyl ether disulfonate to the polyether modified silicone oil is 3:1 to 5:

1. When the organic matter in the exhaust gas is mainly halogenated hydrocarbons, the amount of the synergist is 0.2 to 0.5 parts, the mass ratio of the alkyl diphenyl ether disulfonate to the polyether modified silicone oil is 1:1 to 3:1, and the standing temperature in step S3 is 50°C to 60°C.

9. The process for recovering the emulsifying absorbent according to claim 8, characterized in that, When the organic matter in the exhaust gas includes halogenated hydrocarbons, the synergist is hydroxypropyl-β-cyclodextrin.

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