A modified thermal regeneration method of waste activated carbon

Abstract

This invention belongs to the field of activated carbon regeneration technology, specifically relating to a modified thermal regeneration method for waste activated carbon. This invention enhances the oxidation performance of hydrogen peroxide through complexation with tannic acid and ferric chloride, and promotes the desorption of adsorbates from the surface of waste activated carbon using ultrasound assistance. This deep oxidation desorption removes most soluble pollutants and some blockages. Further deep oxidation desorption of large-molecule organic adsorbates using ozone reduces the harmful fumes that may be generated by traditional pyrolysis. Finally, staged steam activation avoids high-temperature sintering of the activated carbon, and heat is returned to the ozone reactor via a heat exchanger to reduce reaction energy consumption. This modified thermal regeneration method for waste activated carbon uses oxidation combined with thermal regeneration to avoid secondary pollution and reduce reaction energy consumption, resulting in a lower carbon loss rate and improved quality of the regenerated activated carbon.

Description

Technical Field

[0001] This invention belongs to the field of activated carbon regeneration technology, specifically relating to a method for the modified thermal regeneration of waste activated carbon. Background Technology

[0002] Waste activated carbon regeneration refers to the process of restoring the pore structure of activated carbon by altering the adsorption equilibrium between activated carbon and adsorbate using certain physicochemical methods without damaging the original structure of the activated carbon. Thermal regeneration of waste activated carbon generally includes three stages: drying, pyrolysis, and activation. The drying stage involves evaporating moisture and desorbing some low-boiling-point organic matter from the waste activated carbon at 105℃. The pyrolysis stage involves desorbing low-molecular-weight organic matter and pyrolyzing high-molecular-weight organic matter from the waste activated carbon at 105~800℃. The activation stage involves passing steam through the waste activated carbon at 800~1000℃ to decompose the remaining adsorbate, restoring the adsorption performance and pore structure of the activated carbon. Thermal regeneration is currently the most widely used activated carbon regeneration technology, but it still faces technical challenges such as significant activated carbon loss and high regeneration energy consumption.

[0003] Chinese invention patent CN113559831B discloses a vacuum thermal regeneration method for saturated activated carbon adsorbed with VOCs, comprising the following process: Under a vacuum environment of 10Pa-100Pa, the activated carbon adsorbed with VOCs is heated to 280℃-350℃ and held at that temperature for 20-40 minutes. Then, it is cooled with the furnace to below 100℃, at which point the vacuum is broken, thus regenerating the activated carbon adsorbed with VOCs. Compared with traditional thermal desorption and existing vacuum regeneration methods, this invention has higher desorption efficiency and faster rate, while also improving the pore size distribution and increasing the number of micropores in the activated carbon. This allows the activated carbon to recover more than 95% of its adsorption performance after 10 regenerations.

[0004] Chinese invention patent CN114177898B discloses a composite regeneration method for powdered activated carbon, coupling low-temperature thermal regeneration with solvent regeneration and ultrasonic / persulfate regeneration, belonging to the field of water treatment and material regeneration and reuse. Based on the overall characteristics of pollutants adsorbed by the powdered activated carbon, pollutants are classified into easily desorbed and difficult-to-desorb pollutants. The low-temperature thermal regeneration process ensures sufficient desorption of easily desorbed pollutants. Then, for difficult-to-desorb pollutants, liquid-phase regeneration and advanced oxidation regeneration technologies are employed. The combination of heated, enhanced liquid-phase regeneration and ultrasonic / persulfate coupled advanced oxidation regeneration achieves efficient degradation and desorption of difficult-to-desorb pollutants, forming a composite regeneration method combining low-temperature thermal regeneration, solvent regeneration, and ultrasonic / persulfate regeneration. While ensuring the overall regeneration rate of powdered activated carbon, the regeneration temperature of the thermal regeneration process can be significantly reduced, the thermal regeneration time shortened, and the carbon loss rate significantly decreased. However, the existing technology lacks further improvements in the pretreatment and desorption processes of activated carbon to enhance the quality of the regenerated activated carbon. Summary of the Invention

[0005] The purpose of this invention is to provide a modified thermal regeneration method for waste activated carbon, which solves the technical problem in the prior art that the pretreatment and desorption processes of activated carbon have not been further improved to improve the quality of regenerated activated carbon.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for modifying and thermally regenerating waste activated carbon includes the following steps: S1. Pour the waste activated carbon into the oxidation tank, add the regeneration liquid and stir evenly, perform ultrasonic-assisted regeneration, filter out the regeneration waste liquid through a filter press, and dry to obtain pre-desorbed activated carbon. S2. Add the pre-desorbed activated carbon to the ozone reactor, introduce ozone to raise the temperature and perform deep desorption, and obtain deeply desorbed activated carbon. S3. Add the deep desorbed activated carbon into the regeneration furnace, introduce water steam for segmented high-temperature activation, cool the exhaust gas through a heat exchanger, cool the activated carbon through an induced draft fan, and collect to obtain regenerated activated carbon.

[0007] Preferably, in step S1, the solid-liquid ratio of the waste activated carbon and the regenerated liquid is 1:8~10, and the mixture is ultrasonicated at an ultrasonic power of 30~60W for 20~40 minutes, filtered, and then dried at 80~100℃.

[0008] Preferably, the regenerated solution in S1 is prepared by mixing tannic acid, hydrogen peroxide, and ferric chloride with deionized water, wherein the molar ratio of tannic acid, hydrogen peroxide, and ferric chloride is 0.1~0.3:8~10:1, and the concentration of ferric chloride is 140~160 g / m³. 3 The pH of the regenerated solution is 3.5~6.

[0009] Preferably, the ozone concentration in S2 is 50~100mg / L, the ozone flow rate is 50~80kg / h, the mass ratio of ozone dosage to adsorbate in pre-desorbed activated carbon is 3~5:1, the temperature is increased to 200~350℃ at a heating rate of 3~5℃ / min and reacted for 1~2h, the ozone concentration after the reaction is detected to be 5~15mg / L, and the ozone is decomposed by an ozone destroyer and then released into the atmosphere.

[0010] Preferably, in step S3, nitrogen is first introduced to replace the air to prevent the activated carbon from burning under high temperature and high oxygen conditions, then water vapor is introduced, and the temperature is raised to 600-800℃ at a rate of 5-10℃ / min for 0.5-1h, then raised to 800-850℃ for 0.5-1h, and finally nitrogen is introduced to replace the residual tail gas in the regeneration furnace.

[0011] Preferably, the heat accumulated in the heat exchanger in S3 is heated to 200-300°C using ozone and then returned to the ozone reactor. After the heat exchanger cools the exhaust gas to 70-90°C, the exhaust gas is then passed into the regenerated waste liquid in S1, where polyaluminum chloride and polyacrylamide are added for coagulation and precipitation. The dosage of polyaluminum chloride is 100-300 g / m³. 3 The dosage of polyacrylamide is 5~10 g / m³. 3 The exhaust gas is discharged into the atmosphere after the moisture is removed by the demister. The pH of the regenerated waste liquid is controlled at 7. After the precipitates in the regenerated waste liquid are removed by filtration, the regenerated waste liquid can be recycled back into the process flow as reused water.

[0012] The present invention also provides an application of the prepared regenerated activated carbon for adsorbing volatile organic gases in organic coating workshops.

[0013] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention utilizes the complexation of tannic acid and ferric chloride to reduce the formation of iron sludge by chelating iron ions with phenolic hydroxyl groups. It also generates highly oxidizing hydroxyl radicals, which promote the degradation of adsorbates in waste activated carbon by hydrogen peroxide. Furthermore, the complexation of tannic acid and ferric chloride allows for a milder reaction under conditions with a pH greater than 3, reducing the corrosion of the reaction vessel by highly acidic liquids. Ultrasonic assistance generates microbubbles on the surface of the waste activated carbon. The dissociation of these microbubbles produces oxidative radicals that promote the desorption of adsorbates from the surface of the waste activated carbon, thus removing most of the soluble pollutants and some blockages through deep oxidation and desorption.

[0014] 2. This invention reduces chemical reagent residues by oxidizing adsorbates with ozone. The iron ions remaining in the waste activated carbon in the regenerated liquid can catalyze ozone in situ to generate hydroxyl radicals with stronger oxidizing power and non-selectivity. This can significantly improve the deep oxidation and desorption of adsorbates at a relatively low temperature of 200~350℃. Finally, the staged activation with steam avoids high-temperature sintering of activated carbon. The heat is returned to the ozone reactor through a heat exchanger, realizing the cascade utilization of waste heat and reducing reaction energy consumption.

[0015] 3. This invention enhances the oxidation performance of hydrogen peroxide by complexing tannic acid and ferric chloride, and promotes the desorption of adsorbates on the surface of waste activated carbon with ultrasonic assistance. This deep oxidation and desorption process removes most of the soluble pollutants and some blockages. Then, ozone is used for deep oxidation and desorption of large molecular weight organic adsorbates, reducing the harmful flue gas that may be generated by traditional pyrolysis. Finally, water vapor staged activation avoids high-temperature sintering of activated carbon, and the heat is returned to the ozone reactor through a heat exchanger to reduce reaction energy consumption. This results in a reduced carbon loss rate and improved quality of the regenerated activated carbon. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A process flow diagram of a method for modifying and thermally regenerating waste activated carbon according to the present invention is shown. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The waste activated carbon involved in this invention is used in organic paint workshops to adsorb volatile organic gases and is classified as hazardous solid waste. The main organic components of the waste activated carbon are shown in Table 1 below: Table 1 Composition of major organic components Example 1, see Figure 1 As shown in this embodiment, a method for modifying and thermally regenerating waste activated carbon includes the following steps: S1. Pour 1 ton of waste activated carbon into the oxidation tank, add 10 tons of regenerated liquid and stir evenly. The regenerated liquid contains 170 g / m³ of activated carbon. 3 Tannic acid, 280g / m 3 Hydrogen peroxide and 160g / m 3 Ferric chloride was used to control the pH of the regenerated solution to 5. The solution was ultrasonicated at 50W for 20 minutes. The regenerated waste liquid was removed by filtration through a filter press and dried at 100℃ to obtain pre-desorbed activated carbon. S2. Add 1 ton of pre-desorbed activated carbon to the ozone reactor, introduce ozone to raise the temperature for deep desorption, the ozone concentration is 50 mg / L, the ozone flow rate is 50 kg / h, raise the temperature to 200℃ at a heating rate of 3℃ / min and react for 2 hours to obtain deep desorbed activated carbon. After the ozone concentration after the reaction meets the specified concentration, decompose the ozone through an ozone destroyer and then release it into the atmosphere. S3. Add 1 ton of deep-desorbed activated carbon to the regeneration furnace. First, purge the air with nitrogen to prevent combustion of the activated carbon under high temperature and high oxygen conditions. Then, purge with steam at a heating rate of 5℃ / min to raise the temperature to 650℃ and react for 0.5 hours. Then, raise the temperature to 850℃ and react for another 0.5 hours. Cool the exhaust gas through a heat exchanger. After cooling the exhaust gas, pass it into the regeneration waste liquid in S1. Add polyaluminum chloride and polyacrylamide for coagulation and precipitation. The dosage of polyaluminum chloride is 150 g / m³. 3 The dosage of polyacrylamide is 10 g / m³. 3 The exhaust gas is discharged into the atmosphere after the moisture is removed by the demister. The pH of the regenerated waste liquid is controlled at 7. After the precipitate in the regenerated waste liquid is removed by filtration, the regenerated waste liquid can be recycled back into the process flow as recycled water. The heat accumulated in the heat exchanger is heated to 200°C by ozone through the heat exchanger and then fed back into the ozone reactor. The activated carbon is cooled by the induced draft fan and collected to obtain regenerated activated carbon.

[0020] Example 2, see Figure 1 As shown in this embodiment, a method for modifying and thermally regenerating waste activated carbon includes the following steps: S1. Pour 1 t of waste activated carbon into the oxidation tank, add 9.5 t of regenerated liquid and stir evenly. The regenerated liquid contains 200 g / m³ of activated carbon. 3 Tannic acid, 310g / m 3 Hydrogen peroxide and 160g / m 3 Ferric chloride was used to control the pH of the regenerated solution to 4. The solution was ultrasonicated at 30W for 40 minutes. The regenerated waste liquid was removed by filtration through a filter press and dried at 80℃ to obtain pre-desorbed activated carbon. S2. Add 1 ton of pre-desorbed activated carbon to the ozone reactor, introduce ozone to raise the temperature for deep desorption, the ozone concentration is 100 mg / L, the ozone flow rate is 66 kg / h, and the temperature is raised to 250℃ at a rate of 3.5℃ / min for 1 hour to obtain deep desorbed activated carbon. After the ozone concentration after the reaction meets the specified concentration, the ozone is decomposed by an ozone destroyer and then released into the atmosphere. S3. Add 1 ton of deep-desorbed activated carbon to the regeneration furnace. First, purge the air with nitrogen to prevent combustion of the activated carbon under high temperature and high oxygen conditions. Then, purge with steam at a heating rate of 6℃ / min to raise the temperature to 700℃ and react for 1 hour. Then, raise the temperature to 800℃ and react for 0.5 hours. Cool the tail gas through a heat exchanger. After cooling the tail gas, pass the tail gas into the regeneration waste liquid in S1. Add polyaluminum chloride and polyacrylamide for coagulation and precipitation. The dosage of polyaluminum chloride is 220 g / m³. 3 The dosage of polyacrylamide is 8 g / m³. 3 The exhaust gas is discharged into the atmosphere after the moisture is removed by the demister. The pH of the regenerated waste liquid is controlled at 7. After the sediment in the regenerated waste liquid is removed by filtration, the regenerated waste liquid can be recycled back into the process flow as recycled water. The heat accumulated in the heat exchanger is heated to 250°C by ozone through the heat exchanger and then fed back into the ozone reactor. The activated carbon is cooled by the induced draft fan and collected to obtain regenerated activated carbon.

[0021] Example 3, see Figure 1 As shown in this embodiment, a method for modifying and thermally regenerating waste activated carbon includes the following steps: S1. Pour 1 ton of spent activated carbon into the oxidation tank, add 9 tons of regenerated liquid and stir evenly. The regenerated liquid contains 340 g / m³ of activated carbon. 3 Tannins, 330g / m 3 Hydrogen peroxide and 160g / m 3 Ferric chloride was used to control the pH of the regenerated solution to 4.5. The solution was ultrasonically treated with 60W for 20 minutes, filtered through a filter press to remove the regenerated waste liquid, and dried at 80℃ to obtain pre-desorbed activated carbon. S2. Add 1 ton of pre-desorbed activated carbon to the ozone reactor, introduce ozone to raise the temperature for deep desorption, the ozone concentration is 90 mg / L, the ozone flow rate is 54 kg / h, raise the temperature to 300℃ at a rate of 4℃ / min and react for 2 hours to obtain deep desorbed activated carbon. After the ozone concentration after the reaction meets the specified concentration, decompose the ozone through an ozone destroyer and then release it into the atmosphere. S3. Add 1 ton of deep-desorbed activated carbon to the regeneration furnace. First, purge the air with nitrogen to prevent combustion of the activated carbon under high temperature and high oxygen conditions. Then, purge with steam at a heating rate of 10℃ / min to raise the temperature to 800℃ and react for 0.5 hours. Then, raise the temperature to 850℃ and react for 1 hour. Cool the tail gas through a heat exchanger. After cooling the tail gas, pass the tail gas into the regeneration waste liquid in S1. Add polyaluminum chloride and polyacrylamide for coagulation and precipitation. The dosage of polyaluminum chloride is 300 g / m³. 3 The dosage of polyacrylamide is 5 g / m³. 3 The exhaust gas is discharged into the atmosphere after the moisture is removed by the demister. The pH of the regenerated waste liquid is controlled at 7. After the sediment in the regenerated waste liquid is removed by filtration, the regenerated waste liquid can be recycled back into the process flow as recycled water. The heat accumulated in the heat exchanger is heated to 300°C by ozone through the heat exchanger and then fed back into the ozone reactor. The activated carbon is cooled by the induced draft fan and collected to obtain regenerated activated carbon.

[0022] Example 4, see Figure 1 As shown in this embodiment, a method for modifying and thermally regenerating waste activated carbon includes the following steps: S1. Pour 1 ton of waste activated carbon into the oxidation tank, add 8 tons of regenerated liquid and stir evenly. The regenerated liquid contains 500 g / m³ of activated carbon. 3 Tannic acid, 340g / m 3 Hydrogen peroxide and 160g / m 3 Ferric chloride was used to control the pH of the regenerated solution to 3.5. The solution was ultrasonically treated with 40W for 30 minutes, filtered through a filter press to remove the regenerated waste liquid, and dried at 90℃ to obtain pre-desorbed activated carbon. S2. Add 1 ton of pre-desorbed activated carbon to the ozone reactor, introduce ozone to raise the temperature for deep desorption, the ozone concentration is 84 mg / L, the ozone flow rate is 72 kg / h, raise the temperature to 350℃ at a heating rate of 5℃ / min and react for 1 hour to obtain deep desorbed activated carbon. After the ozone concentration after the reaction meets the specified concentration, decompose the ozone through an ozone destroyer and then release it into the atmosphere. S3. Add 1 ton of deep-desorbed activated carbon to the regeneration furnace. First, purge the air with nitrogen to prevent combustion of the activated carbon under high temperature and high oxygen conditions. Then, purge with steam at a heating rate of 5℃ / min to raise the temperature to 750℃ and react for 1 hour. Then, raise the temperature to 830℃ and react for 0.5 hours. Cool the tail gas through a heat exchanger. After cooling the tail gas, pass the tail gas into the regeneration waste liquid in S1. Add polyaluminum chloride and polyacrylamide for coagulation and precipitation. The dosage of polyaluminum chloride is 250 g / m³. 3 The dosage of polyacrylamide is 9 g / m³. 3The exhaust gas is discharged into the atmosphere after the moisture is removed by the demister. The pH of the regenerated waste liquid is controlled at 7. After the sediment in the regenerated waste liquid is removed by filtration, the regenerated waste liquid can be recycled back into the process flow as recycled water. The heat accumulated in the heat exchanger is heated to 300°C by ozone through the heat exchanger and then fed back into the ozone reactor. The activated carbon is cooled by the induced draft fan and collected to obtain regenerated activated carbon.

[0023] Example 5, see Figure 1 As shown in this embodiment, a method for modifying and thermally regenerating waste activated carbon includes the following steps: S1. Pour 1 ton of waste activated carbon into the oxidation tank, add 10 tons of regenerated liquid and stir evenly. The regenerated liquid contains 170 g / m³ of activated carbon. 3 Tannic acid, 310g / m 3 Hydrogen peroxide and 140g / m 3 Ferric chloride was used to control the pH of the regenerated solution to 6. The solution was ultrasonicated at 60W for 40 minutes. The regenerated waste liquid was removed by filtration through a filter press and dried at 100℃ to obtain pre-desorbed activated carbon. S2. Add 1 ton of pre-desorbed activated carbon to the ozone reactor, introduce ozone to raise the temperature for deep desorption, the ozone concentration is 90 mg / L, the ozone flow rate is 65 kg / h, raise the temperature to 200℃ at a rate of 3℃ / min and react for 2 hours to obtain deep desorbed activated carbon. After the ozone concentration after the reaction meets the specified concentration, decompose the ozone through an ozone destroyer and then release it into the atmosphere. S3. Add 1 ton of deep-desorbed activated carbon to the regeneration furnace. First, purge the air with nitrogen to prevent combustion of the activated carbon under high temperature and high oxygen conditions. Then, purge with steam at a heating rate of 10℃ / min to raise the temperature to 650℃ and react for 0.5 hours. Then, raise the temperature to 800℃ and react for 1 hour. Cool the tail gas through a heat exchanger. After cooling the tail gas, pass the tail gas into the regeneration waste liquid in S1. Add polyaluminum chloride and polyacrylamide for coagulation and precipitation. The dosage of polyaluminum chloride is 150 g / m³. 3 The dosage of polyacrylamide is 5 g / m³. 3 The exhaust gas is discharged into the atmosphere after the moisture is removed by the demister. The pH of the regenerated waste liquid is controlled at 7. After the precipitate in the regenerated waste liquid is removed by filtration, the regenerated waste liquid can be recycled back into the process flow as recycled water. The heat accumulated in the heat exchanger is heated to 200°C by ozone through the heat exchanger and then fed back into the ozone reactor. The activated carbon is cooled by the induced draft fan and collected to obtain regenerated activated carbon.

[0024] Example 6, see Figure 1 As shown in this embodiment, a method for modifying and thermally regenerating waste activated carbon includes the following steps: S1. Pour 1 ton of waste activated carbon into the oxidation tank, add 10 tons of regenerated liquid and stir evenly. The regenerated liquid contains 170 g / m³ of activated carbon. 3Tannic acid, 300g / m 3 Hydrogen peroxide and 150g / m 3 Ferric chloride was used to control the pH of the regenerated solution to 5.5. The solution was ultrasonicated at 50W for 40 minutes. The regenerated waste liquid was removed by filtration through a filter press and dried at 100℃ to obtain pre-desorbed activated carbon. S2. Add 1 ton of pre-desorbed activated carbon to the ozone reactor, introduce ozone to raise the temperature for deep desorption, the ozone concentration is 100 mg / L, the ozone flow rate is 50 kg / h, and the temperature is raised to 250℃ at a heating rate of 3.5℃ / min for 2 hours to obtain deep desorbed activated carbon. After the ozone concentration after the reaction meets the specified concentration, the ozone is decomposed by an ozone destroyer and then released into the atmosphere. S3. Add 1 ton of deep-desorbed activated carbon to the regeneration furnace. First, purge the air with nitrogen to prevent combustion of the activated carbon under high temperature and high oxygen conditions. Then, purge with steam at a heating rate of 5℃ / min to raise the temperature to 600℃ and react for 0.5 hours. Then, raise the temperature to 800℃ and react for another 0.5 hours. Cool the tail gas through a heat exchanger. After cooling the tail gas, pass the tail gas into the regeneration waste liquid in S1. Add polyaluminum chloride and polyacrylamide for coagulation and precipitation. The dosage of polyaluminum chloride is 240 g / m³. 3 The dosage of polyacrylamide is 8 g / m³. 3 The exhaust gas is discharged into the atmosphere after the moisture is removed by the demister. The pH of the regenerated waste liquid is controlled at 7. After the sediment in the regenerated waste liquid is removed by filtration, the regenerated waste liquid can be recycled back into the process flow as recycled water. The heat accumulated in the heat exchanger is heated to 250°C by ozone through the heat exchanger and then fed back into the ozone reactor. The activated carbon is cooled by the induced draft fan and collected to obtain regenerated activated carbon.

[0025] Example 7, see Figure 1 As shown in this embodiment, a method for modifying and thermally regenerating waste activated carbon includes the following steps: S1. Pour 1 ton of waste activated carbon into the oxidation tank, add 10 tons of regenerated liquid and stir evenly. The regenerated liquid contains 255 g / m³ of activated carbon. 3 Tannic acid, 310g / m 3 Hydrogen peroxide and 150g / m 3 Ferric chloride was used to control the pH of the regenerated solution to 6. The solution was ultrasonicated at 30W for 30 minutes. The regenerated waste liquid was removed by filtration through a filter press and dried at 100℃ to obtain pre-desorbed activated carbon. S2. Add 1 ton of pre-desorbed activated carbon to the ozone reactor, introduce ozone to raise the temperature for deep desorption, the ozone concentration is 75 mg / L, the ozone flow rate is 75 kg / h, raise the temperature to 200℃ at a heating rate of 4℃ / min and react for 2 hours to obtain deep desorbed activated carbon. After the ozone concentration after the reaction meets the specified concentration, decompose the ozone through an ozone destroyer and then release it into the atmosphere. S3. Add 1 ton of deep-desorbed activated carbon to the regeneration furnace. First, purge the air with nitrogen to prevent combustion of the activated carbon under high temperature and high oxygen conditions. Then, purge with steam at a heating rate of 7.5℃ / min to raise the temperature to 650℃ and react for 1 hour. Then, raise the temperature to 850℃ and react for 0.5 hours. Cool the tail gas through a heat exchanger. After the tail gas is cooled by the heat exchanger, it is then passed into the regeneration waste liquid in S1. Add polyaluminum chloride and polyacrylamide for coagulation and precipitation. The dosage of polyaluminum chloride is 300 g / m³. 3 The dosage of polyacrylamide is 10 g / m³. 3 The exhaust gas is discharged into the atmosphere after the moisture is removed by the demister. The pH of the regenerated waste liquid is controlled at 7. After the precipitate in the regenerated waste liquid is removed by filtration, the regenerated waste liquid can be recycled back into the process flow as recycled water. The heat accumulated in the heat exchanger is heated to 200°C by ozone through the heat exchanger and then fed back into the ozone reactor. The activated carbon is cooled by the induced draft fan and collected to obtain regenerated activated carbon.

[0026] Comparative Example 1 differs from Example 1 in that the waste activated carbon is directly subjected to ozone oxidation without the addition of regeneration liquid for pre-desorption.

[0027] Comparative Example 2 differs from Example 1 in that the pre-desorbed activated carbon is directly added to the regeneration furnace for thermal regeneration without ozone oxidation.

[0028] Comparative Example 3 differs from Example 1 in that the waste activated carbon is directly added to the regeneration furnace for thermal regeneration.

[0029] Comparative Example 4 differs from Example 1 in that tannic acid is not added to the regenerated solution.

[0030] Performance testing The specific surface area, total pore volume, micropore volume, and microporosity of the regenerated activated carbon prepared in Example 1 and Comparative Example 3 were measured using a specific surface area analyzer.

[0031] The test results are shown in Table 2 below: Table 2 Basic Properties of Regenerated Activated Carbon The carbon loss rate of the regenerated activated carbon prepared in each embodiment and comparative example is calculated using the following formula: η is the carbon loss rate; m0 is the initial activated carbon mass, in kg; m1 represents the mass of regenerated activated carbon, expressed in kg.

[0032] The iodine adsorption values ​​of the regenerated activated carbon prepared in each example and comparative example were tested according to GB / T 12496.8-2015 "Test Methods for Iodine Adsorption Value of Wood-based Activated Carbon".

[0033] The methylene blue adsorption values ​​of the regenerated activated carbon prepared in each example and comparative example were tested according to GB / T 12496.10-1999 "Test Methods for Wood-based Activated Carbon - Determination of Methylene Blue Adsorption Value".

[0034] The strength retention rate of the regenerated activated carbon prepared in each example and comparative example was tested according to GB / T 12496.6-1999 "Test Methods for Strength Determination of Wood-based Activated Carbon".

[0035] The test results are shown in Table 3 below: Table 3 Adsorption performance test results According to the data in the table above, the specific surface area of ​​the embodiment is 1034 m². 2 / g, with a microporosity of 51.7%. In contrast, the direct regeneration of waste activated carbon using steam in Comparative Example 3 necessitates a prolonged high-temperature decomposition of the adsorbate, resulting in severe damage to the pore structure of the regenerated activated carbon, thus reducing its specific surface area to 879 m². 2 / g, microporosity 38.3%, carbon loss rate of 5.9-10.6% in Examples 1-7, iodine adsorption value 829.5-854.3 mg / g, methylene blue adsorption value 107.5-123.6 mg / g, strength retention rate 88.1-91.3%, indicating that the regenerated activated carbon prepared by the modified thermal regeneration method of waste activated carbon of the present invention has good pore recovery, unobstructed micropores, and excellent adsorption performance, and can be used in organic coating workshops to adsorb volatile organic gases.

[0036] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0037] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for modifying and thermally regenerating waste activated carbon, characterized in that, Includes the following steps: S1. Pour the waste activated carbon into the oxidation tank, add the regeneration liquid and stir evenly, perform ultrasonic-assisted regeneration, filter out the regeneration waste liquid through a filter press, and dry to obtain pre-desorbed activated carbon. S2. Add the pre-desorbed activated carbon to the ozone reactor, introduce ozone to raise the temperature and perform deep desorption, and obtain deeply desorbed activated carbon. S3. Add the deep desorbed activated carbon into the regeneration furnace, introduce water steam for segmented high-temperature activation, cool the exhaust gas through a heat exchanger, cool the activated carbon through an induced draft fan, and collect to obtain regenerated activated carbon.

2. The method for modifying and thermally regenerating waste activated carbon according to claim 1, characterized in that, The regenerated solution in S1 is prepared by mixing tannic acid, hydrogen peroxide, and ferric chloride with deionized water. The molar ratio of tannic acid, hydrogen peroxide, and ferric chloride is 0.1~0.3:8~10:1, and the concentration of ferric chloride is 140~160 g / m³. 3 The pH of the regenerated solution is 3.5~6.

3. The method for modifying and thermally regenerating waste activated carbon according to claim 1, characterized in that, The solid-liquid ratio of the waste activated carbon and the regenerated liquid in S1 is 1:8~10. The mixture is ultrasonicated at an ultrasonic power of 30~60W for 20~40 minutes, filtered, and then dried at 80~100℃.

4. The method for modifying and thermally regenerating waste activated carbon according to claim 1, characterized in that, The ozone concentration in S2 is 50~100mg / L, the ozone flow rate is 50~80kg / h, the mass ratio of ozone dosage to adsorbate in pre-desorbed activated carbon is 3~5:1, the temperature is increased to 200~350℃ at a heating rate of 3~5℃ / min and reacted for 1~2h, the ozone concentration after the reaction is detected to be 5~15mg / L, and the ozone is decomposed by an ozone destroyer and then released into the atmosphere.

5. The method for modifying and thermally regenerating waste activated carbon according to claim 1, characterized in that, In step S3, nitrogen is first introduced to replace the air to prevent the activated carbon from burning under high temperature and high oxygen conditions. Then, water vapor is introduced to raise the temperature to 600-800℃ at a rate of 5-10℃ / min and react for 0.5-1h. The temperature is then raised to 800-850℃ and reacted for 0.5-1h. Finally, nitrogen is introduced to replace the residual tail gas in the regeneration furnace.

6. The method for modifying and thermally regenerating waste activated carbon according to claim 1, characterized in that, The heat accumulated in the heat exchanger in S3 heats the ozone to 200-300°C and then returns it to the ozone reactor.

7. The method for modifying and thermally regenerating waste activated carbon according to claim 1, characterized in that, After the heat exchanger cools the exhaust gas to 70-90℃, the exhaust gas is then passed into the regeneration waste liquid in S1, where polyaluminum chloride and polyacrylamide are added for coagulation and precipitation. The dosage of polyaluminum chloride is 100-300 g / m³. 3 The dosage of polyacrylamide is 5~10 g / m³. 3 The exhaust gas is discharged into the atmosphere after the moisture is removed by the demister. The pH of the regenerated waste liquid is controlled at 7. After the precipitates in the regenerated waste liquid are removed by filtration, the regenerated waste liquid can be recycled back into the process flow as reused water.

8. The method for modifying and thermally regenerating waste activated carbon according to claim 1, characterized in that, The regenerated activated carbon prepared by the modified thermal regeneration method is used to adsorb volatile organic gases in an organic coating workshop.

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