Multi-stage adsorption recovery method for organic gas by means of biological NANO composite activated carbon

Abstract

The present invention relates to the technical field of gas treatment, and particularly relates to a multi-stage adsorption recovery method for organic gases by means of biological nano composite activated carbon. The method comprises the following steps: preparing an activated carbon composite, i.e. nFeOOH@AC, of nano-hydroxyl iron modified corn husk and bamboo shoot skin by using an ethanol dispersion method, which composite can be used for the adsorption of organic gases; and introducing a mixed gas containing a target organic matter into a system comprising at least two biological nano composite activated carbon adsorbers, which are connected in series, at a preset flow rate Q (m3 / h), wherein each adsorber is filled with the biological nano composite activated carbon with a density ρ (kg / m3), the specific surface area thereof is S (m2 / g), and the average pore diameter is d (nm), thereby achieving multi-stage adsorption. The beneficial effects comprise: utilizing the high specific surface area and excellent adsorption performance of the biological nano composite activated carbon, and combining the multi-stage adsorption system, such that efficient recovery of organic gases can be achieved, thereby significantly improving the recovery efficiency. Compared with a traditional treatment method, this method is low in energy consumption, extra fuel is not needed, and the adsorption material can be recycled, thereby reducing resource consumption and waste generation, and conforming to the environmentally friendly development concept.

Description

A multi-stage adsorption recovery method for organic gases using bio-nanocomposite activated carbon Technical Field

[0001] The present invention relates to the technical field of gas treatment, and in particular to a method for recovering organic gases by multi-stage adsorption using bio-nano composite activated carbon. Background Art

[0002] In industrial production, a large number of volatile organic compounds (VOCs), such as toluene, acetone, and other solvents, are widely used. However, the emission of these organic gases not only causes serious environmental pollution but also wastes valuable resources. While traditional treatment methods such as combustion, absorption, and condensation can treat these waste gases to a certain extent, they often suffer from high energy consumption, low treatment efficiency, and the generation of secondary pollution. Therefore, the development of efficient, low-energy, and environmentally friendly organic gas recovery technologies is particularly important.

[0003] As a novel adsorption material, bio-nanocomposite activated carbon combines the biocompatibility of biomaterials with the high surface area and high adsorption properties of nanomaterials while recycling perishable solid waste. It demonstrates great potential in the field of organic gas adsorption. Its unique nanostructure and bioactive components provide excellent selective adsorption for specific organic gases. It is also easily regenerated and recyclable, reducing treatment costs.

[0004] However, a single adsorber often finds it difficult to achieve ideal recovery efficiency and treatment capacity when treating high-concentration, large-flow organic waste gas. Summary of the Invention

[0005] The purpose of the present invention is to provide a multi-stage adsorption and recovery method for organic gases using bio-nanocomposite activated carbon to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for multi-stage adsorption and recovery of organic gases using bio-nanocomposite activated carbon, the method comprising the following steps:

[0007] Prepare bionano composite activated carbon, and then use the bionano composite activated carbon in an absorption device to adsorb organic gas. The preparation method of the bionano composite activated carbon is as follows:

[0008] 1) Pretreatment: Immerse the bamboo shoot skins in a phosphoric acid solution for 24 to 48 hours, then wash with deionized water until neutral, dry at 40 to 60°C for 20 to 25 hours, and grind for later use.

[0009] 2) Preparation of biochar AC: The raw material treated in 1) was heated from room temperature to a carbonization temperature of 200-400°C at a heating rate of 5°C / min in a vacuum atmosphere, and then cooled to room temperature after 5-20 minutes to obtain biochar AC. The AC was ground, passed through a 120-mesh sieve, and placed in a desiccator for later use;

[0010] 3) Preparation of bionanocomposite activated carbon: The AC and FeCl3 solutions are injected into an ethanol solution and mixed, and then the pH value is adjusted to 6-8 with hydrochloric acid and NaOH solutions. The reaction is carried out under magnetic stirring at 150 rpm to 250 rpm for 20-25 hours. After filtration, the solid is transferred to an oven and dried at 60-80°C for 20-25 hours. Finally, the obtained solid is washed with deionized water until neutral, dried at 60-80°C to obtain hydroxy iron modified activated carbon nFeOOH@AC, i.e., bionanocomposite activated carbon. The mixed gas containing the target organic matter is introduced at a preset flow rate Q (m³ / h) into a system comprising at least two bionanocomposite activated carbon adsorbers connected in series, each adsorber being filled with bionanocomposite activated carbon having a density of ρ (kg / m³), a specific surface area of ​​S (m² / g), and an average pore size of d (nm) to achieve multi-stage adsorption.

[0011] Preferably, the method further comprises:

[0012] Set the adsorption saturation threshold η_threshold (%) of each adsorber stage. When the real-time adsorption efficiency η of a certain adsorber stage is lower than this threshold, the automatic control system will automatically direct the gas to the next unsaturated adsorber stage. The adsorption efficiency η is calculated by the following formula:

[0013] eta=(1-Cin​Cout​​)×100%

[0014] Where Cin​ is the organic matter concentration at the air inlet (mg / m³), and Cout​ is the organic matter concentration at the air outlet (mg / m³).

[0015] Preferably, it also includes:

[0016] The organic matter concentration at the inlet and outlet of each adsorber stage is monitored and recorded in real time, the adsorption efficiency is calculated, and the number of adsorption stages is dynamically adjusted according to the adsorption efficiency to optimize the recovery efficiency.

[0017] Preferably, it also includes:

[0018] When all the adsorbers have reached the adsorption saturation state, the adsorbers are desorbed using saturated steam as the desorbent. The steam pressure is controlled within the range of P (MPa) and the desorption temperature T_desorption (°C) is slightly higher than the adsorption temperature to ensure effective desorption.

[0019] Preferably, further comprising:

[0020] The organic vapor generated by desorption is sent to the condenser for condensation treatment. The condensation temperature T_condensation (°C) is controlled within a certain range to maximize the condensation efficiency. The condensed organic liquid is separated by an oil-water separator.

[0021] Preferably, it also includes:

[0022] The oil-water separator separates the condensate into pure organic solvent and water through gravity sedimentation or centrifugal separation technology, with a separation efficiency not less than E_separation (%), and collects them separately.

[0023] Preferably, it also includes:

[0024] The adsorber after desorption is dried and purged with air or inert gas. The purging time t_drying (h) is determined according to the adsorber size and filling amount. After purging, it is cooled to room temperature and ready to enter the next working cycle.

[0025] Preferably, it also includes:

[0026] Design and implement an automated control system that uses PLC or DCS to automate gas flow control, adsorber switching, desorption and condensation processes, including safety interlocks to prevent abnormal operation.

[0027] Preferably, further comprising:

[0028] An energy efficiency evaluation module is integrated into the automated control system. By monitoring the adsorption level, desorption conditions, and condensation efficiency parameters, the overall energy efficiency E_system of the system is calculated, and continuous optimization is carried out to improve recovery efficiency and reduce energy consumption.

[0029] Preferably, it also includes:

[0030] The bio-nanocomposite activated carbon is regenerated regularly to restore its adsorption performance. The regeneration treatment includes high-temperature heat treatment or chemical regeneration to ensure long-term stable operation of the system.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention proposes a multi-stage adsorption recovery method for organic gases using bio-nanocomposite activated carbon. By utilizing the high specific surface area and excellent adsorption performance of bio-nanocomposite activated carbon, combined with a multi-stage adsorption system, the method can achieve efficient recovery of organic gases and significantly improve recovery efficiency. Compared with traditional treatment methods, the method has low energy consumption, does not require additional fuel, and the adsorption material is renewable, reducing resource consumption and waste generation, and conforming to the development concept of green environmental protection. The system has a high degree of automation, and gas flow control, adsorber switching, desorption and condensation processes are automated through PLC or DCS, reducing manual intervention and improving operational safety and stability. The method is suitable for the recovery and treatment of a variety of organic gases, such as toluene, acetone, benzene series, etc., and parameters such as adsorption stage and desorption conditions can be adjusted according to actual needs to meet the treatment requirements under different working conditions. By recovering organic solvents, enterprises can not only reduce waste gas emissions and reduce environmental pressure, but also reuse the recovered solvents in production, reduce production costs and improve economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0034] In order to clearly and completely describe the objectives and technical solutions of the present invention and make the advantages more clearly understood, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are part of the embodiments of the present invention, not all of them, and are only used to explain the embodiments of the present invention, not to limit the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] In the first embodiment, referring to FIG1 , the present invention provides a technical solution: a method for recovering organic gases by multi-stage adsorption of bio-nanocomposite activated carbon, the method comprising the following steps:

[0036] Prepare bionano composite activated carbon, and then use the bionano composite activated carbon in an absorption device to adsorb organic gas. The preparation method of the bionano composite activated carbon is as follows:

[0037] 1) Pretreatment: Immerse the bamboo shoots in a phosphoric acid solution for 24 to 48 hours, then wash with deionized water until neutral, dry at 40 to 60°C for 20 to 25 hours, and grind for later use.

[0038] 2) Preparation of biochar AC: The raw material treated in 1) was heated from room temperature to a carbonization temperature of 200-400°C at a heating rate of 5°C / min in a vacuum atmosphere, and then cooled to room temperature after 5-20 minutes to obtain biochar AC. The AC was ground, passed through a 120-mesh sieve, and placed in a desiccator for later use;

[0039] 3) Preparation of bionanocomposite activated carbon: In an ethanol solution, the AC and FeCl3 solution are injected and mixed, and then the pH value is adjusted to 6-8 with hydrochloric acid and NaOH solution. The reaction is carried out under magnetic stirring at 150 rpm to 250 rpm for 20-25 hours. After filtering, the solid is transferred to an oven and dried at 60-80°C for 20-25 hours. Finally, the obtained solid is washed with deionized water until neutral, and dried at 60-80°C to obtain hydroxy iron modified activated carbon nFeOOH@AC, i.e., bionanocomposite activated carbon;

[0040] A mixed gas containing target organic matter is introduced into a system comprising at least two bio-nanocomposite activated carbon adsorbers connected in series at a preset flow rate Q (m³ / h). Each adsorber is filled with bio-nanocomposite activated carbon with a density of ρ (kg / m³), a specific surface area of ​​S (m² / g), and an average pore size of d (nm) to achieve multi-stage adsorption.

[0041] Set the adsorption saturation threshold η_threshold (%) of each adsorber stage. When the real-time adsorption efficiency η of a certain adsorber stage is lower than this threshold, the automatic control system will automatically direct the gas to the next unsaturated adsorber stage. The adsorption efficiency η is calculated by the following formula:

[0042] eta=(1-Cin​Cout​​)×100%

[0043] Where Cin​ is the organic matter concentration at the air inlet (mg / m³), and Cout​ is the organic matter concentration at the air outlet (mg / m³).

[0044] The organic matter concentration at the inlet and outlet of each adsorber stage is monitored and recorded in real time, the adsorption efficiency is calculated, and the number of adsorption stages is dynamically adjusted according to the adsorption efficiency to optimize the recovery efficiency.

[0045] When all the adsorbers have reached the adsorption saturation state, the adsorbers are desorbed using saturated steam as the desorbent. The steam pressure is controlled within the range of P (MPa) and the desorption temperature T_desorption (°C) is slightly higher than the adsorption temperature to ensure effective desorption.

[0046] The organic vapor generated by desorption is sent to the condenser for condensation treatment. The condensation temperature T_condensation (°C) is controlled within a certain range to maximize the condensation efficiency. The condensed organic liquid is separated by an oil-water separator.

[0047] The oil-water separator separates the condensate into pure organic solvent and water through gravity sedimentation or centrifugal separation technology, with a separation efficiency not less than E_separation (%), and collects them separately.

[0048] The adsorber after desorption is dried and purged with air or inert gas. The purging time t_drying (h) is determined according to the adsorber size and filling amount. After purging, it is cooled to room temperature and ready to enter the next working cycle.

[0049] Design and implement an automated control system that uses PLC or DCS to automate gas flow control, adsorber switching, desorption and condensation processes, including safety interlocks to prevent abnormal operation.

[0050] An energy efficiency evaluation module is integrated into the automated control system. By monitoring the adsorption level, desorption conditions, and condensation efficiency parameters, the overall energy efficiency E_system of the system is calculated, and continuous optimization is carried out to improve recovery efficiency and reduce energy consumption.

[0051] The bio-nanocomposite activated carbon is regenerated regularly to restore its adsorption performance. The regeneration treatment includes high-temperature heat treatment or chemical regeneration to ensure long-term stable operation of the system.

[0052] Example 2, based on Example 1, proposes that a chemical plant use bio-nano composite activated carbon to perform multi-stage adsorption recovery on the discharged toluene waste gas.

[0053] Parameter settings:

[0054] System configuration: A three-stage bio-nano composite activated carbon adsorber is used. Each stage of the adsorber is filled with bio-nano composite activated carbon with a density of 1.5 kg / m³, a specific surface area of ​​1500 m² / g, and an average pore size of 5 nm.

[0055] Gas flow rate: Q = 500 m³ / h

[0056] Inlet air concentration: Toluene concentration C_in = 500 mg / m³

[0057] Adsorption efficiency threshold: η_threshold = 80%

[0058] Desorption conditions: steam pressure P = 0.2 MPa, desorption temperature T_desorption = 120°C

[0059] Condensation temperature: T_condensation = 40°C

[0060] Separation efficiency: E_separation = 98%

[0061] Purge time: t_drying = 1.5 h

[0062] Implementation steps:

[0063] The exhaust gas enters the first-stage adsorber at a flow rate of 500 m³ / h. When the adsorption efficiency drops below 80%, it automatically switches to the second stage, and so on.

[0064] After all the adsorbers were saturated, desorption treatment was carried out, and the desorption steam pressure was controlled at 0.2 MPa and the temperature was 120 °C.

[0065] The toluene vapor generated by desorption is condensed at 40°C, and the condensate is separated through an oil-water separator with a separation efficiency of 98%. The recovered toluene solution is stored or reused.

[0066] After the adsorber was desorbed and dried for 1.5 hours, it was ready to enter the next working cycle.

[0067] Example 3, based on Example 2, proposes that a printing factory use bio-nano composite activated carbon to perform multi-stage adsorption recovery of volatile organic compounds (VOCs).

[0068] Parameter settings:

[0069] System configuration: Two-stage series adsorption system, each stage filled with bio-nanocomposite activated carbon with a density of 1.2 kg / m³, a specific surface area of ​​1200 m² / g, and an average pore size of 3 nm.

[0070] Gas flow rate: Q = 300 m³ / h

[0071] Intake air concentration: VOCs concentration C_in = 300 mg / m³

[0072] Adsorption efficiency threshold: η_threshold = 85%

[0073] Desorption conditions: steam pressure P = 0.15 MPa, desorption temperature T_desorption = 110°C

[0074] Condensation temperature: T_condensation = 35°C

[0075] Separation efficiency: E_separation = 97%

[0076] Purge time: t_drying = 1 h

[0077] Implementation steps:

[0078] VOCs waste gas enters the first-stage adsorber at a flow rate of 300 m³ / h. The adsorption efficiency is monitored in real time and switches to the second stage when it is lower than 85%.

[0079] After adsorption saturation, desorption treatment was carried out with a steam pressure of 0.15 MPa and a temperature of 110°C.

[0080] The condensation temperature was set at 35°C, and the condensate was treated in an oil-water separator with a separation efficiency of 97% to recover the VOCs solution.

[0081] After drying for 1 hour, the adsorber is ready for use again.

[0082] Example 4, based on Example 3, proposes that a certain electronics factory use bio-nano composite activated carbon to perform multi-stage adsorption recovery on acetone discharged in the workshop.

[0083] Parameter settings:

[0084] System configuration: Four-stage series adsorption system, each stage filled with bio-nanocomposite activated carbon with a density of 1.4 kg / m³, a specific surface area of ​​1300 m² / g, and an average pore size of 4 nm.

[0085] Gas flow: Q = 450 m³ / h

[0086] Inlet air concentration: acetone concentration C_in = 450 mg / m³

[0087] Adsorption efficiency threshold: η_threshold = 75%

[0088] Desorption conditions: steam pressure P = 0.25 MPa, desorption temperature T_desorption = 125°C

[0089] Condensation temperature: T_condensation = 45°C

[0090] Separation efficiency: E_separation = 99%

[0091] Purge time: t_drying = 2 h

[0092] Implementation steps:

[0093] Acetone waste gas passes through four-stage adsorbers in sequence at a flow rate of 450 m³ / h, and automatically switches when the adsorption efficiency of each stage is lower than 75%.

[0094] After adsorption saturation, high-temperature steam desorption was performed at a pressure of 0.25 MPa and a temperature of 125°C.

[0095] The condensation temperature is set at 45°C, which efficiently condenses the acetone vapor and obtains a high-purity acetone solution through an oil-water separator with a separation efficiency of 99%.

[0096] After 2 hours of drying, the adsorber is ready to enter the next working cycle.

[0097] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A multi-stage adsorption and recovery method for organic gases using bio-nanocomposite activated carbon, characterized in that: The method comprises the following steps: Prepare bionano composite activated carbon, and then use the bionano composite activated carbon in an absorption device to adsorb organic gas. The preparation method of the bionano composite activated carbon is as follows: 1) Pretreatment: Immerse the bamboo shoot skins in a phosphoric acid solution for 24 to 48 hours, then wash with deionized water until neutral, dry at 40 to 60°C for 20 to 25 hours, and grind for later use. 2) Preparation of biochar AC: The raw material treated in 1) was heated from room temperature to a carbonization temperature of 200-400°C at a heating rate of 5°C / min in a vacuum atmosphere, and then cooled to room temperature after 5-20 minutes to obtain biochar AC. The AC was ground, passed through a 120-mesh sieve, and placed in a desiccator for later use; 3) Preparation of bionanocomposite activated carbon: In an ethanol solution, the AC and FeCl3 solution are injected and mixed, and then the pH value is adjusted to 6-8 with hydrochloric acid and NaOH solution. The reaction is carried out under magnetic stirring at 150 rpm to 250 rpm for 20-25 hours. After filtering, the solid is transferred to an oven and dried at 60-80°C for 20-25 hours. Finally, the obtained solid is washed with deionized water until neutral, and dried at 60-80°C to obtain hydroxy iron modified activated carbon nFeOOH@AC, i.e., bionanocomposite activated carbon; A mixed gas containing target organic matter is introduced into a system comprising at least two bio-nanocomposite activated carbon adsorbers connected in series at a preset flow rate Q (m³ / h). Each adsorber is filled with bio-nanocomposite activated carbon with a density of ρ (kg / m³), a specific surface area of S (m² / g), and an average pore size of d (nm) to achieve multi-stage adsorption.

2. The method for multi-stage adsorption and recovery of organic gases by bio-nanocomposite activated carbon according to claim 1, characterized in that: The method further comprises: Set the adsorption saturation threshold η_threshold (%) of each adsorber stage. When the real-time adsorption efficiency η of a certain adsorber stage is lower than this threshold, the automatic control system will automatically direct the gas to the next unsaturated adsorber stage. The adsorption efficiency η is calculated by the following formula: eta=(1-Cin​Cout​​)×100% Where Cin​ is the organic matter concentration at the air inlet (mg / m³), and Cout​ is the organic matter concentration at the air outlet (mg / m³).

3. The method for multi-stage adsorption and recovery of organic gases by bio-nanocomposite activated carbon according to claim 2, characterized in that: Also includes: The organic matter concentration at the inlet and outlet of each adsorber stage is monitored and recorded in real time, the adsorption efficiency is calculated, and the number of adsorption stages is dynamically adjusted according to the adsorption efficiency to optimize the recovery efficiency.

4. The method for multi-stage adsorption and recovery of organic gases by bio-nanocomposite activated carbon according to claim 1, characterized in that: Also includes: When all the adsorbers have reached the adsorption saturation state, the adsorbers are desorbed using saturated steam as the desorbent. The steam pressure is controlled within the range of P (MPa) and the desorption temperature T_desorption (°C) is slightly higher than the adsorption temperature to ensure effective desorption.

5. The method for multi-stage adsorption and recovery of organic gases by bio-nanocomposite activated carbon according to claim 1, characterized in that: Further including: The organic vapor generated by desorption is sent to the condenser for condensation treatment. The condensation temperature T_condensation (°C) is controlled within a certain range to maximize the condensation efficiency. The condensed organic liquid is separated by an oil-water separator.

6. The method for multi-stage adsorption and recovery of organic gases by bio-nanocomposite activated carbon according to claim 1, characterized in that: Also includes: The oil-water separator separates the condensate into pure organic solvent and water through gravity sedimentation or centrifugal separation technology, with a separation efficiency not less than E_separation (%), and collects them separately.

7. The method for multi-stage adsorption and recovery of organic gases by bio-nanocomposite activated carbon according to claim 1, characterized in that: Also includes: The adsorber after desorption is dried and purged with air or inert gas. The purging time t_drying (h) is determined according to the adsorber size and filling amount. After purging, it is cooled to room temperature and ready to enter the next working cycle.

8. The method for multi-stage adsorption and recovery of organic gases by bio-nanocomposite activated carbon according to claim 1, characterized in that: Also includes: Design and implement an automated control system that uses PLC or DCS to automate gas flow control, adsorber switching, desorption and condensation processes, including safety interlocks to prevent abnormal operation.

9. The method for multi-stage adsorption and recovery of organic gases by bio-nanocomposite activated carbon according to claim 1, characterized in that: Further including: An energy efficiency evaluation module is integrated into the automated control system. By monitoring the adsorption level, desorption conditions, and condensation efficiency parameters, the overall energy efficiency E_system of the system is calculated, and continuous optimization is carried out to improve recovery efficiency and reduce energy consumption.

10. The method for multi-stage adsorption and recovery of organic gases by bio-nanocomposite activated carbon according to claim 1, characterized in that: Also includes: The bio-nanocomposite activated carbon is regenerated regularly to restore its adsorption performance. The regeneration treatment includes high-temperature heat treatment or chemical regeneration to ensure long-term stable operation of the system.

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