Development activating agent waste liquid recovery technology in graded porous capacitor carbon preparation process
By using potassium bicarbonate activator and carbon dioxide recovery process, the problems of environmental pollution and high costs in the preparation of porous carbon materials are solved, and the efficient recovery of activator and the green production of capacitive carbon materials are achieved.
Patent Information
- Application Number
- CN202411245379.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-06
- Publication Date
- 2025-03-21
AI Technical Summary
Prior art In the preparation of porous carbon materials, the strong alkali agents and pickling process used cause environmental pollution and high costs, and fail to effectively recover the activator waste liquid.
Potassium bicarbonate is used as the activator, and the mixture of petroleum asphalt and potassium bicarbonate is calcined, followed by water bath heating and vacuum drying to obtain fractionated porous capacitance carbon, and potassium bicarbonate is recovered by carbon dioxide treatment.
It realizes efficient recycling and reuse of activators, reduces production costs, avoids the damage to the environment by strong alkaline substances, and uses carbon dioxide to reduce greenhouse gas emissions.
Smart Images
Figure CN119660736A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of energy storage technology, and in particular to a process for recovering activator waste liquid during the preparation of graded porous capacitor carbon. Background Art
[0002] With the rapid development of science and technology and the rapid consumption of non-renewable energy, people are increasingly demanding new electrochemical energy storage devices that store and convert renewable energy. Supercapacitors have both high power density and ultra-long cycle life, and have great application prospects. So far, supercapacitors constructed of low-cost, highly stable carbon-based materials have become the mainstream of the market.
[0003] Electrode materials are the main factors that determine the performance of lithium-ion capacitors. Porous carbon materials are widely used in the field of electrochemical energy storage due to their excellent physical and chemical properties. In the face of supercapacitor carbon technology, while exploring its preparation methods, we should also pay attention to the environmental protection of the preparation process. Traditionally, the template method has been widely used in the synthesis of porous carbon materials. This method usually includes the use of strong alkaline agents such as potassium hydroxide, magnesium oxide and zinc oxide. However, in the subsequent template removal stage, it is common practice to use strong acid washing. When these preparation processes are expanded to industrial production, the large costs, potential hazards and adverse environmental impacts associated with such large-scale production cannot be ignored. Therefore, solving the post-treatment problem of waste liquid is also an important part of the industrialization process of asphalt-based porous carbon activated by potassium bicarbonate, thereby reducing production costs and realizing resource recycling and sustainable development.
[0004] In view of this, the present invention is proposed. Summary of the invention
[0005] One of the purposes of the present invention is to provide a green and pollution-free method for the preparation of graded porous capacitor carbon and the recycling method of the activator potassium bicarbonate, so as to at least solve one of the technical problems existing in the prior art.
[0006] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:
[0007] The present invention provides a process for recovering waste activator liquid during the preparation of hierarchical porous capacitor carbon, comprising the following steps:
[0008] A. calcining a mixture of petroleum asphalt and a potassium bicarbonate activator to obtain a carbon material;
[0009] B. heating the carbon material obtained in A in a water bath and performing solid-liquid separation to obtain a solid powder and a filtrate;
[0010] C. Drying the solid powder obtained in B under vacuum conditions to obtain hierarchical porous capacitor carbon;
[0011] D. Concentrating the filtrate obtained in B to obtain a saturated solution of mixed potassium salts;
[0012] E. Adding carbon dioxide to the saturated solution of the mixed potassium salt obtained in D until the pH reaches 7 to 8, and then performing solid-liquid separation to obtain potassium bicarbonate crystals;
[0013] F. Wash and purify the crude potassium bicarbonate salt obtained in E, and then dry it to obtain potassium bicarbonate powder.
[0014] Furthermore, step B also includes the step of washing and filtering the obtained solid powder at least twice, and combining the filtrates as the filtrate obtained in step B.
[0015] Furthermore, in step D, the concentration comprises heating the filtrate at a temperature of 70-80°C and concentrating by evaporation, preferably heating at a temperature of 75°C.
[0016] Furthermore, the conditions for introducing carbon dioxide in step E include the following:
[0017] ① After the mixed potassium salt is concentrated into a saturated solution, carbon dioxide is introduced under normal temperature and pressure;
[0018] ② After the mixed potassium salt is concentrated into a saturated solution, carbon dioxide is introduced under pressure at room temperature.
[0019] Preferably, ② after the mixed potassium salt is concentrated into a saturated solution, carbon dioxide is introduced under pressure at room temperature.
[0020] The change of pH value during the introduction of carbon dioxide was observed. The pH value ranged from 8 to 7, preferably 8.
[0021] Furthermore, in step F, the purification conditions are water washing or alcohol washing, and preferably ethanol is used to purify the crude potassium bicarbonate salt.
[0022] Furthermore, the wet potassium bicarbonate is separated after purification, and the drying conditions are high temperature vacuum drying or freezing, preferably freeze drying to obtain dry potassium bicarbonate.
[0023] Compared with the prior art, the present invention has the following beneficial effects:
[0024] The present invention uses potassium bicarbonate as an activator, which can not only reduce the adverse effects of corrosive reagents on the environment during the production process, but also recycle it to the maximum extent, with a recovery rate of 80%, greatly saving costs. It effectively avoids the untreated filtrate in the prior art containing potassium hydroxide and potassium carbonate, and the strong alkaline substances causing great damage to the land and water quality. At the same time, the carbon dioxide used in the present invention can be selected from the flue gas generated during the calcination process of preparing carbon materials, thereby reducing the emission of greenhouse gases. Therefore, in the field of capacitor carbon material production, it is necessary to promote ecologically feasible and environmentally friendly development, and there is a need for vigorous development in the field of process engineering. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0026] Figure 1 The XRD phase characterization result diagram provided for Example 1 of the present invention and the purchased potassium bicarbonate;
[0027] Figure 2 XRD phase characterization result diagram provided for Examples 2 and 3 of the present invention;
[0028] Figure 3 The XRD phase characterization result diagram provided for the comparative example of the present invention;
[0029] Figure 4 This is a scanning electron microscope (SEM) result image of potassium bicarbonate purchased by the present invention;
[0030] Figure 5 The SEM result diagram provided for Example 1 of the present invention;
[0031] Figure 6 A specific surface area result diagram provided for an embodiment of the present invention;
[0032] Figure 7 and Figure 8 The particle size result diagram provided by the embodiment of the present invention, wherein Figure 7 For the purchased potassium bicarbonate, Figure 8 Potassium bicarbonate of the embodiment;
[0033] Fig. 9 and Fig.10 The electrochemical test results of the capacitor assembled by using the activated porous carbon prepared by using the original potassium bicarbonate and the recycled potassium bicarbonate provided in the embodiment of the present invention are shown in FIG. Fig. 9 The scan rate is 50 mV s-1 The result of cyclic voltammetry test is shown in Figure 2. Fig.10 1Ag -1 Graph showing the results of constant current charge and discharge tests at a current density of . DETAILED DESCRIPTION
[0034] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear, however, in the case of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, unless otherwise stated, the use of "or" means "and / or". In addition, the use of the term "including" and other forms is non-limiting.
[0035] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0036] According to one aspect of the present invention, there is provided a method for preparing hierarchical porous capacitor carbon, comprising the following steps:
[0037] Step A , calcining a mixture of petroleum asphalt and a potassium bicarbonate activator to obtain a carbon material;
[0038] The liquid intermediate phase is formed when petroleum asphalt and potassium bicarbonate are heated. At high temperatures, the excess free radicals and volatile organic compounds in petroleum asphalt are released, promoting more active sites. At the same time, potassium bicarbonate decomposes to form potassium-containing compounds. These compounds play a vital role in guiding the formation of the basic framework of porous capacitor carbon.
[0039] The decomposition equation of potassium bicarbonate during calcination includes:
[0040] 2KHCO3 → K2CO3 + CO2 + H2O (1)
[0041] K2CO3 → K2O + CO2 (2)
[0042] K2CO3 + 2C → 2K + 3CO (3)
[0043] K2O + C → 2K + CO (4)
[0044] CO2 + C → 2CO (5).
[0045] Step B, washing the carbon material obtained in A with water and then heating it in a water bath, followed by solid-liquid separation to obtain a solid powder and a filtrate;
[0046] Potassium-containing compounds exist in the generated carbon material. After washing with water, the potassium-containing compounds become a mixed solution of potassium carbonate and potassium hydroxide, and solid-liquid separation is performed.
[0047] In some preferred embodiments, the method further comprises washing and filtering the obtained solid powder at least twice, and combining the filtrates as the filtrate obtained in step B. The activator can be removed more thoroughly by multiple washing and filtering, thereby ensuring the purity of the product graded porous capacitor carbon. The filtrates of the washing and filtering are combined as the filtrate obtained in step B for subsequent circulation operation, thereby further reducing the production cost and reducing the discharge of waste liquid, which is green and environmentally friendly.
[0048] Step C , drying the solid powder obtained in B under vacuum conditions to obtain hierarchical porous capacitor carbon;
[0049] Step D , heating and concentrating the filtrate obtained in B to obtain a saturated solution of mixed potassium salts;
[0050] During the heating process of the mixed solution of potassium carbonate and potassium hydroxide, potassium hydroxide reacts with water and carbon dioxide in the air, and most of it turns into potassium carbonate, waiting for the solution to be saturated. The reaction equation is: CO2+2KOH=K2CO3+H2O.
[0051] In some preferred embodiments, the concentration comprises heating the filtrate at a temperature of 70-80°C and concentrating by evaporation, for example, 70°C, 72°C, 75°C, 78°C or 80°C, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable. Preferably, the filtrate is heated at a temperature of 75°C.
[0052] Step E , introducing carbon dioxide into the saturated solution of the mixed potassium salt obtained in D, observing the pH value, which can be reduced to 8, 7.5 or 7, but preferably 8, and performing solid-liquid separation to obtain crude potassium bicarbonate;
[0053] A large amount of carbon dioxide is introduced into the saturated solution for carbonization, and the precipitated crystals are converted into potassium carbonate into potassium bicarbonate. The reaction equation is: K2CO3+CO2+H2O=2KHCO3.
[0054] In some preferred embodiments, the crude potassium bicarbonate is purified using ethanol to obtain wet potassium bicarbonate, which is then separated and dried to obtain dry potassium bicarbonate. The drying method includes high-temperature vacuum drying and freeze drying, preferably freeze drying.
[0055] The present invention uses potassium bicarbonate as an activator, which can not only reduce the adverse effects of corrosive reagents on the environment during the production process, but also recycle it to the maximum extent, with a recovery rate of 80%, greatly saving costs. It effectively avoids the untreated filtrate in the prior art containing potassium hydroxide and potassium carbonate, and the strong alkaline substances causing great damage to the land and water quality. At the same time, the carbon dioxide used in the present invention can be selected from the flue gas generated during the calcination process of preparing carbon materials, thereby reducing the emission of greenhouse gases. Therefore, in the field of capacitor carbon material production, it is necessary to promote ecologically feasible and environmentally friendly development, and there is a need for vigorous development in the field of process engineering.
[0056] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.
[0057] Example 1
[0058] This embodiment provides a method for preparing hierarchical porous capacitor carbon, comprising the following steps:
[0059] a. Petroleum asphalt and potassium bicarbonate activator are fully rolled and ground to obtain a uniform mixed material.
[0060] b. Under nitrogen atmosphere, calcination was carried out in a tubular furnace at a temperature of 800°C, a heating rate of 5°C / min, and a time of 120 min. After calcination, the mixture was cooled to room temperature to obtain a carbon material.
[0061] c. Wash the carbon material obtained in step b with deionized water, and heat it in a water bath at 60°C with stirring. Use a vacuum filtration device to separate the solid and liquid. Wash and filter the separated solid powder several times, and retain the filtrate.
[0062] d. The final solid powder was dried in a vacuum oven at 80° C. to obtain the final hierarchical porous capacitor carbon.
[0063] The filtrate in e and c contains potassium carbonate and potassium hydroxide. The filtrate is placed in a crystallization dish and heated at 75°C, evaporated and concentrated to finally obtain a saturated solution of mixed potassium salts, which is cooled to room temperature. At this time, the pH value of the solution is 11.
[0064] f. Introduce carbon dioxide into the saturated solution of mixed potassium salt under pressure at room temperature. White crystals appear during this process, and the mixed potassium solution is converted into potassium bicarbonate crude salt and filtrate. When the pH value of the filtrate drops to 8, stop passing carbon dioxide and perform solid-liquid separation.
[0065] g. Add ethanol to purify the crude potassium bicarbonate salt.
[0066] h. freeze-drying the separated wet potassium bicarbonate to obtain dry potassium bicarbonate.
[0067] Example 2
[0068] This embodiment provides a method for preparing hierarchical porous capacitor carbon, comprising the following steps:
[0069] a. Petroleum asphalt and potassium bicarbonate activator are fully rolled and ground to obtain a uniform mixed material.
[0070] b. Under nitrogen atmosphere, calcination was carried out in a tubular furnace at a temperature of 800°C, a heating rate of 5°C / min, and a time of 120 min. After calcination, the mixture was cooled to room temperature to obtain a carbon material.
[0071] c. Wash the carbon material obtained in step b with deionized water, and heat it in a water bath at 60°C with stirring. Use a vacuum filtration device to separate the solid and liquid. Wash and filter the separated solid powder several times, and retain the filtrate.
[0072] d. The final solid powder was dried in a vacuum oven at 80° C. to obtain the final hierarchical porous capacitor carbon.
[0073] The filtrate in e and c contains potassium carbonate and potassium hydroxide. The filtrate is placed in a crystallization dish and heated at 80°C, evaporated and concentrated to finally obtain a saturated solution of mixed potassium salts, which is cooled to room temperature. At this time, the pH value of the solution is 11.
[0074] f. Pass carbon dioxide into the saturated solution of mixed potassium salt at normal temperature and pressure. White crystals appear in the process, and the mixed potassium solution is converted into potassium bicarbonate crude salt and filtrate. When the pH value of the filtrate drops to 7.5, stop passing carbon dioxide and perform solid-liquid separation.
[0075] g. Add water to purify the crude potassium bicarbonate salt.
[0076] h. Dry the separated wet potassium bicarbonate under high temperature and vacuum to obtain dry potassium bicarbonate.
[0077] Example 3
[0078] This embodiment provides a method for preparing hierarchical porous capacitor carbon, comprising the following steps:
[0079] a. Petroleum asphalt and potassium bicarbonate activator are fully rolled and ground to obtain a uniform mixed material.
[0080] b. Under nitrogen atmosphere, calcination was carried out in a tubular furnace at a temperature of 800°C, a heating rate of 5°C / min, and a time of 120 min. After calcination, the mixture was cooled to room temperature to obtain a carbon material.
[0081] c. Wash the carbon material obtained in step b with deionized water, and heat it in a water bath at 60°C with stirring. Use a vacuum filtration device to separate the solid and liquid. Wash and filter the separated solid powder several times, and retain the filtrate.
[0082] d. The final solid powder was dried in a vacuum oven at 80° C. to obtain the final hierarchical porous capacitor carbon.
[0083] The filtrate in e and c contains potassium carbonate and potassium hydroxide. The filtrate is placed in a crystallization dish and heated at 70°C, evaporated and concentrated to finally obtain a saturated solution of mixed potassium salts, which is cooled to room temperature. At this time, the pH value of the solution is 11.
[0084] f. Pass carbon dioxide into the saturated solution of mixed potassium salt at normal temperature and pressure. White crystals appear in the process, and the mixed potassium solution is converted into potassium bicarbonate crude salt and filtrate. When the pH value of the filtrate drops to 7, stop passing carbon dioxide and perform solid-liquid separation.
[0085] g. Add water to purify the crude potassium bicarbonate salt.
[0086] h. Dry the separated wet potassium bicarbonate under high temperature and vacuum to obtain dry potassium bicarbonate.
[0087] Example 4
[0088] This embodiment provides a method for preparing hierarchical porous capacitor carbon, comprising the following steps:
[0089] a. Petroleum asphalt and potassium bicarbonate activator are fully rolled and ground to obtain a uniform mixed material.
[0090] b. In a nitrogen atmosphere, the mixture is placed in a tubular furnace for calcination. After calcination, the mixture is cooled to room temperature to obtain a carbon material.
[0091] c. Wash the carbon material obtained in step b with deionized water, and heat it in a water bath at 60°C with stirring. Use a vacuum filtration device to separate the solid and liquid. Wash and filter the separated solid powder several times, and retain the filtrate.
[0092] d. The final solid powder was dried in a vacuum oven at 80° C. to obtain the final hierarchical porous capacitor carbon.
[0093] The filtrate in e and c contains potassium carbonate and potassium hydroxide. The filtrate is placed in a crystallization dish and heated at 60°C, evaporated and concentrated to finally obtain a saturated solution of mixed potassium salts, which is then cooled to room temperature.
[0094] f. Pass carbon dioxide into the saturated solution of mixed potassium salt at room temperature. White crystals appear in the process, and the mixed potassium solution is converted into potassium bicarbonate crude salt and filtrate. When the pH value of the filtrate drops to 8.5, stop passing carbon dioxide and perform solid-liquid separation.
[0095] g. Add ethanol to purify the crude potassium bicarbonate salt.
[0096] h. freeze-drying the separated wet potassium bicarbonate to obtain dry potassium bicarbonate.
[0097] Comparative Example 1
[0098] Compared with Example 1, this comparative example has the following differences:
[0099] In step e, the filtrate is placed in a crystallization dish and heated at 85° C. to directly evaporate and crystallize, and finally a mixed salt solid powder is obtained.
[0100] Comparative Example 2
[0101] Compared with Example 1, this comparative example has the following differences:
[0102] In steps e and f, the filtrate is placed in a crystallization dish and heated at 85° C. for evaporation and concentration, while carbon dioxide gas is introduced to finally obtain a saturated solution of mixed potassium salts, which is then cooled to room temperature.
[0103] Experimental example
[0104] In order to save experimental costs, taking Example 1 as an example, the prepared potassium bicarbonate was verified as follows, and the specific experiment is as follows:
[0105] 1. Phase characterization
[0106] X-ray diffraction (XRD) technology uses the law of X-ray diffraction to analyze the atomic distribution inside the crystal of a material.
[0107] The results are as follows Figure 1 As shown, the recovered potassium bicarbonate was characterized by XRD phase, which was consistent with the standard card of potassium bicarbonate, indicating that this method is applicable to the preparation of potassium bicarbonate. Figure 2 Examples 2 and 3 are relatively consistent with the XRD standard card of potassium bicarbonate, indicating the feasibility of this method. However, compared with Example 1, the physical phase of Example 1 is closer to the physical phase of standard potassium bicarbonate. Figure 3 The results of the comparative example are completely inconsistent with the XRD standard card of potassium bicarbonate.
[0108] 2. Scanning electron microscope
[0109] Scanning Electron Microscopy (SEM) acts on samples through electron beams, stimulating electrical signals and then forming images. It can observe the morphology and scale of the microscopic surface of the material and is adjustable between 20 times and 200,000 times.
[0110] The results are as follows Figure 4 and Figure 5 As shown, the microscopic morphology was characterized by scanning electron microscopy (SEM). The recovered potassium bicarbonate had a morphology similar to that of the purchased potassium bicarbonate, with a smooth surface and long particles.
[0111] 3. Specific surface area
[0112] The specific surface areas of the two were obtained by nitrogen adsorption and desorption. The nitrogen adsorption and desorption test uses the capillary condensation phenomenon and the principle of volume equivalent substitution to determine the specific surface area, pore size distribution and pore volume of the material.
[0113] The results are as follows Figure 6 As shown, the specific surface area of raw potassium bicarbonate is 0.378m 2 g -1 The recovered potassium bicarbonate is 0.141m 2 g -1 There is a certain gap between the two in specific surface area because the original potassium bicarbonate used in the experiment is AR99%, which has been refined to a certain extent to increase its specific surface area.
[0114] 4. Particle size
[0115] Laser particle size analysis uses laser as the light source. The angular distribution of the diffracted and scattered light energy is related to the particle size, thereby determining the particle size distribution of the material. Figure 7 and Figure 8 As shown, the particle sizes of both are almost between 150-600 microns, but the original potassium bicarbonate also has particles smaller than 50 microns, which may be the reason for its large specific surface area.
[0116] 5. Electrochemical test
[0117] Active porous carbon was prepared using both materials and assembled into symmetrical double-layer capacitors for electrochemical testing. Button supercapacitors were assembled in an argon glove box with a water / oxygen content of ≤0.01ppm in the following order: positive electrode shell, nickel foam coated with active material, 100μL electrolyte, glass fiber diaphragm, 100μL electrolyte, nickel foam coated with active material, gasket, shrapnel, negative electrode shell. Button supercapacitors were then encapsulated using a CR2032 battery sealer.
[0118] The results are as follows Fig. 9 As shown in the cyclic voltammetry (CV) data, the CV curve shows that the scanning rate is 50 mV s -1 When the porous carbon prepared by using potassium bicarbonate as an activator in Example 1 also has an ideal double electric layer rectangular shape, and the integrated area is almost the same as that of the original potassium bicarbonate, indicating that the porous carbon prepared by the two methods maintains the same capacitance performance.
[0119] Fig.10 At 1A g -1 The porous carbon prepared by using potassium bicarbonate provided in Example 1 and commercially available potassium bicarbonate (Aladdin, Lot#H2126385) as activators was subjected to constant current charge and discharge test (GCD) for comparison at a current density of .
[0120] Calculate its capacitance:
[0121] Cs(F g-1) represents the specific capacitance of the electrode material, I(A) represents the discharge current, Δt(s) represents the time for complete discharge, m(g) represents the total mass of the active materials of the positive and negative electrodes in the double electrode, and ΔV(V) represents the width of the potential window.
[0122] Calculated: At 1A g -1 When the potassium bicarbonate used as the activator in Example 1 is used, the specific capacitance of the porous carbon is 85 Fg -1 , compared with the mass specific capacitance (82 F g -1 ) to remain consistent.
[0123] The above results show that the preparation method of hierarchical porous capacitor carbon provided by the present invention can be used to recycle potassium bicarbonate and reuse it as an activator, which can still achieve similar performance to the porous carbon prepared by the original AR99% potassium bicarbonate. Promoting ecologically feasible development is in line with the national development strategy and there is a need for vigorous development in the field of process engineering.
[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A process for recovering waste activator liquid during the preparation of hierarchical porous capacitor carbon, characterized in that: The steps include: A. calcining a mixture of petroleum asphalt and potassium bicarbonate to obtain a carbon material; B. washing the carbon material obtained in A and heating it in a water bath, followed by solid-liquid separation to obtain a solid powder and a filtrate; C. Drying the solid powder obtained in B under vacuum conditions to obtain hierarchical porous capacitor carbon; D. heating and concentrating the filtrate obtained in B to obtain a saturated solution of mixed potassium salts; E. Passing carbon dioxide into the saturated solution of the mixed potassium salt obtained in D until the pH is 8, and then performing solid-liquid separation to obtain potassium bicarbonate crystals; F. Wash and purify the crude potassium bicarbonate salt obtained in E, and then dry it to obtain potassium bicarbonate powder.
2. The recycling process according to claim 1, characterized in that: Step B also includes the step of washing and filtering the obtained solid powder at least twice, and combining the filtrates as the filtrate obtained in step B.
3. The recycling process according to claim 1, characterized in that: In step D, the concentration comprises heating the filtrate at a temperature of 70-80°C and concentrating by evaporation, preferably heating at a temperature of 75°C.
4. The recycling process according to claim 1, characterized in that: The conditions for introducing carbon dioxide in step E include the following: ① After the mixed potassium salt is concentrated into a saturated solution, carbon dioxide is introduced under normal temperature and pressure; ② After the mixed potassium salt is concentrated into a saturated solution, carbon dioxide is introduced under pressure at room temperature. Preferably, after the mixed potassium salt is concentrated into a saturated solution, carbon dioxide is introduced under pressure at room temperature; The pH value during the process of introducing carbon dioxide is 8 to 7, preferably 8.
5. The recycling process according to claim 1, characterized in that: In step F, the purification conditions are water washing or alcohol washing, and preferably ethanol is used to purify the crude potassium bicarbonate salt.
6. The preparation method according to claim 5, characterized in that: After purification, the wet potassium bicarbonate is separated, and the drying conditions are high temperature vacuum drying or freezing, preferably freeze drying to obtain dry potassium bicarbonate.