Method for preparing derived porous carbon adsorption material by electrochemical method for refining humic acid

Abstract

The application discloses a method for preparing a derived porous carbon adsorption material by electrochemical extraction of humic acid, and belongs to the technical field of high-value utilization of low-rank coal derived porous carbon materials and heavy metal ion adsorption application. The humic acid is extracted by an electrochemical oxidation method of low-rank coal, and a humic acid derived porous carbon adsorption material is prepared by high-temperature catalytic pyrolysis. The method is simple in process, easy to control in reaction condition and free of pollution. The method uses the extracted humic acid as raw material, and prepares the porous carbon adsorption material by high-temperature catalytic pyrolysis, which can be applied to adsorb heavy metal ions and has a better adsorption effect. The method provides an application basis for mass preparation and large-scale application of the porous carbon adsorption material, provides a new idea and reference for resource utilization, efficient and high-value utilization of low-rank coal, and further widens the application value.

Description

Technical Field

[0001] This invention relates to the field of high-value-added utilization of low-rank coal-derived porous carbon materials and their application in heavy metal ion adsorption technology, and in particular to a method for preparing derived porous carbon adsorption materials by electrochemical extraction of humic acid. Background Technology

[0002] Low-rank coal is a type of coal with high moisture content and low carbon content, often located deep within coal seams and formed in a relatively short time. Although its price is lower (only 20% to 30% of that of high-rank coal), its low grade, low calorific value, high moisture content, high volatile matter, and low thermal stability limit its utilization, easily leading to environmental pollution and energy loss. In some regions, low-rank coal is used to produce fertilizers and chemical products. Its rich humic acid content is widely used in agriculture, industry, medicine and health, environmental protection, and carbon material preparation, driving the development of related extraction technologies.

[0003] Humic acid extraction involves extraction, purification, and separation processes. Common methods include alkaline extraction, acid extraction, microbial lysis, and organic solvent extraction. Alkaline extraction is one of the mainstream methods, where coal reacts with alkaline substances to generate soluble humate salts, which are then acidified to obtain humic acid. However, this method can only extract free humic acid, requiring oxidative pretreatment to improve the extraction rate. Regenerated humic acid is obtained by oxidatively degrading large molecular organic matter in coal. Electrochemical oxidation utilizes an electrolyte to simultaneously carry out oxidation and dissolution, converting coal particles into humic acid products through anodic oxidation. This method improves the extraction rate and solves problems such as easy structural damage, long oxidation cycles, high energy consumption, and environmental pollution, making it a promising preparation method.

[0004] Porous carbon possesses a highly developed internal pore structure, exhibiting high specific surface area, large porosity, and various pore structures including micropores, mesopores, and macropores. Containing functional groups or atoms such as oxygen, sulfur, and nitrogen, it possesses high physicochemical stability, mechanical strength, and surface reactivity, making it widely used in adsorption, catalysis, and energy storage, particularly in water treatment for the removal of heavy metal ions and organic pollutants. Humic acid, on the other hand, is composed of a cross-linked unit framework of oxygen-containing functional groups, exhibiting a sponge-like texture and high chemical reactivity. As a novel carbon precursor, humic acid can be used to prepare porous carbon with high porosity and oxygen-rich surface chemistry, thus promoting the application of porous carbon in the adsorption field. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing derived porous carbon adsorbent materials by electrochemical extraction of humic acid. This method is simple, the reaction conditions are easy to control, and it is pollution-free. Using the extracted humic acid as raw material, porous carbon adsorbent materials are prepared by high-temperature catalytic pyrolysis. These materials can be used to adsorb heavy metal ions and exhibit excellent adsorption effects. This provides an application basis for the large-scale preparation and application of porous carbon adsorbent materials. At the same time, it provides new ideas and references for the resource utilization, high efficiency, and high added value of low-rank coal, further broadening its application value.

[0006] To achieve the above objectives, this invention provides a method for preparing humic acid-derived porous carbon adsorbent materials through electrochemical extraction of humic acid. The method involves extracting humic acid via electrochemical oxidation of low-rank coal and preparing humic acid-derived porous carbon adsorbent materials through high-temperature catalytic pyrolysis, comprising the following steps:

[0007] Step 1: Low-rank coal is crushed, ball-milled, and sieved; coal powder sample is weighed and added to the anode area of ​​H-type electrolytic cell, alkaline solution is added, and the mixture is stirred to make a uniform coal slurry;

[0008] Step 2: The experiment was conducted using the H-type electrolytic cell from Step 1, with the anode region containing low-rank coal slurry and the cathode region containing an equal volume and concentration of alkaline solution. A three-electrode system was used, with the anode as the working electrode and the cathode as the counter electrode. The anode was stirred during the reaction, and the voltage, electrochemical reaction time, and alkaline solution concentration were controlled as variables. The experiment was conducted using the constant potential method under normal temperature and pressure.

[0009] Step 3: After the electrochemical reaction is completed, the anode coal slurry after the reaction in Step 2 is centrifuged. The upper layer solution obtained by separation is titrated with acid solution to pH=1-2. After standing for 1 hour, it is centrifuged again. The solid product obtained is vacuum dried to obtain humic acid.

[0010] Step 4: Grind the humic acid obtained in Step 3 into powder, mix it with the metal catalyst at different mass ratios to obtain a mixed sample, impregnate the mixed sample in deionized water at a certain solid-liquid ratio and stir the mixture, then dry the impregnated mixture in a forced-air drying oven, grind and sieve it after drying to obtain a uniform mixture, and finally pyrolyze the dried mixture at high temperature to obtain the final humic acid-derived porous carbon adsorbent material.

[0011] Preferably, the concentration of the alkaline solution in step one is 0.5-3 mol / L.

[0012] Preferably, in step two, the anode stirring speed is 100-800 r / min, the voltage of the working electrode relative to the reference electrode is 0.4-2V, and the electrochemical reaction time is 1-24h.

[0013] Preferably, in step three, the centrifugation separation step is set with a centrifuge speed of 3000-8000 rad / min and a centrifugation time of 3-10 min.

[0014] Preferably, the acid solution in step three is hydrochloric acid or a mixed acid, wherein the mixed acid includes nitric acid and phosphoric acid, wherein the volume ratio of nitric acid to phosphoric acid is 1-2:3-5, the concentration of nitric acid is 2-5 mol / L, and the concentration of phosphoric acid is 5-15 mol / L.

[0015] Preferably, the vacuum drying conditions in step three are a vacuum oven at 60-80°C and a drying time of 12-24 hours.

[0016] Preferably, the metal catalyst in step four is potassium ferrate, and the mass ratio of humic acid powder to metal catalyst is 1:0.25-1.5.

[0017] Preferably, in step four, the solid-liquid ratio of the mixed sample to deionized water is 1:2-5, the stirring time is 8-24 hours, and the drying conditions are a forced-air drying oven at 80-110℃.

[0018] Preferably, the high-temperature pyrolysis temperature in step four is 600-900℃, and pyrolysis is carried out in a tube furnace with a heating rate of 2-5℃ / min and a holding time of 2-5h.

[0019] The present invention also provides an application of low-rank coal electrochemical extraction of humic acid and its derived porous carbon in the adsorption of heavy metal ions.

[0020] Therefore, the method for preparing derived porous carbon adsorbent materials by electrochemical extraction of humic acid described above has the following beneficial effects:

[0021] (1) By simplifying the humic acid extraction process, the oxidation and alkali dissolution processes can be completed in one step, while the humic acid yield can be greatly increased. The humic acid yield can reach more than 73%. Compared with the traditional humic acid extraction process, the process is simple, the reaction conditions are easy to control, and there is no pollution. Combined with the abundant source of raw materials and low cost, it has great potential for large-scale production expansion.

[0022] (2) Using extracted humic acid as raw material, a porous carbon adsorption material with a porous structure was synthesized with a metal catalyst in a closed environment. It was applied to the adsorption material of heavy metal ions and showed a better adsorption effect.

[0023] (3) It provides an application basis for the preparation of porous carbon adsorption materials in large quantities and large-scale application, and at the same time provides new ideas for the resource utilization, high efficiency and high added value utilization of low-rank coal, further broadening its application value.

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0025] Figure 1 This is a sample preparation flowchart of an embodiment of the method for preparing derived porous carbon adsorbent materials by electrochemical extraction of humic acid according to the present invention;

[0026] Figure 2 This is the XRD curve of humic acid-derived porous carbon obtained in Example 1 of the method for preparing derived porous carbon adsorbent material by electrochemical extraction of humic acid according to the present invention.

[0027] Figure 3 This is the nitrogen adsorption-desorption isotherm curve of the humic acid-derived porous carbon adsorbent material obtained in Example 1 of the present invention, which is a method for preparing derived porous carbon adsorbent material by electrochemical extraction of humic acid.

[0028] Figure 4 This is the pore size distribution curve of the humic acid-derived porous carbon adsorbent material obtained in Example 1 of the method for preparing derived porous carbon adsorbent material by electrochemical extraction of humic acid according to the present invention.

[0029] Figure 5 This invention relates to a method for preparing derived porous carbon adsorbents by electrochemical extraction of humic acid. Example 1 shows the humic acid-derived porous carbon adsorbent obtained from this method, which is effective for Cu... 2+ Co 2+ Ni 2+ Pb 2+ Images showing the adsorption amounts of four heavy metal ions.

[0030] Figure 6 This invention relates to a method for preparing derived porous carbon adsorbents by electrochemical extraction of humic acid. Example 1 shows the humic acid-derived porous carbon adsorbent obtained from this method, which is effective for Cu... 2+ Co 2+ Ni 2+ Pb 2+ Adsorption rate images of four heavy metal ions. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0033] Example

[0034] like Figure 1As shown, this invention provides a method for preparing humic acid-derived porous carbon adsorbent materials through electrochemical extraction of humic acid. The method involves extracting humic acid via electrochemical oxidation of low-rank coal and preparing humic acid-derived porous carbon adsorbent materials through high-temperature catalytic pyrolysis, comprising the following steps:

[0035] Step 1: The low-rank coal is crushed, ball-milled, and sieved. The coal powder sample is weighed and added to the anode area of ​​the H-type electrolytic cell. An alkaline solution is added to decompose the raw material and form a solution. After adding the alkaline solution, the mixture is stirred to make a homogeneous coal slurry. The low-rank coal is lignite or bituminous coal, and the concentration of the alkaline solution is 0.5-3 mol / L.

[0036] Step 2: The experiment was conducted using the H-type electrolytic cell from Step 1, with the anode region containing low-rank coal slurry and the cathode region containing an equal volume and concentration of alkaline solution. A three-electrode system was used, with the anode as the working electrode and the cathode as the counter electrode. The anode was stirred during the reaction, and the voltage, electrochemical reaction time, and alkaline solution concentration were controlled as variables. The experiment was conducted using the constant potential method under normal temperature and pressure. The anode stirring speed was 100-800 r / min, the voltage of the working electrode relative to the reference electrode was 0.4-2V, and the electrochemical reaction time was 1-24h.

[0037] Step 3: After the electrochemical reaction is completed, the anode coal slurry from Step 2 is centrifuged. The centrifuge speed is set to 3000-8000 rad / min, and the centrifugation time is 3-10 min. Centrifugation is used to separate insoluble substances from the solution. The resulting supernatant is titrated with an acid solution to pH 1-2. The acid solution is used to precipitate solids from the solution. By soaking the raw material powder in the acid solution, substances soluble in the acidic solution are separated from the humic acid by centrifugation. The acid solution is hydrochloric acid or a mixed acid, including nitric acid and phosphoric acid, where the volume ratio of nitric acid to phosphoric acid is 1-2:3-5, the nitric acid concentration is 2-5 mol / L, and the phosphoric acid concentration is 5-15 mol / L. After standing for 1 hour, centrifugation is performed again. The resulting solid product is then vacuum dried in a vacuum oven at 60-80℃ for 12-24 hours to obtain humic acid.

[0038] Step 4: Grind the humic acid obtained in Step 3 into powder and mix it with a metal catalyst at different mass ratios to obtain a mixed sample. The metal catalyst is potassium ferrate, and the mass ratio of humic acid powder to metal catalyst is 1:0.25-1.5. The metal catalyst is used to catalyze the formation of humic acid-derived porous carbon adsorbent materials. The mixed sample is impregnated in deionized water at a certain solid-liquid ratio, and the mixture is stirred. Impregnation modifies the mixed sample. The impregnated mixture is then dried in a forced-air drying oven at a solid-liquid ratio of 1:2-5, a stirring time of 8-24 hours, and a drying temperature of 80-110℃. After drying, the mixture is ground and sieved to obtain a homogeneous mixture. Finally, the dried mixture is subjected to high-temperature pyrolysis at 600-900℃ using a tube furnace at a heating rate of 2-5℃ / min. The isothermal time is 2-5 hours to obtain the final humic acid-derived porous carbon adsorbent material.

[0039] Example 1

[0040] This embodiment uses low-rank coal powder as raw material and employs an electrochemical oxidation method to extract humic acid from lignite, followed by high-temperature catalytic pyrolysis to prepare humic acid-derived porous carbon adsorbent materials. The method is carried out according to the following steps:

[0041] 1. Raw material pretreatment

[0042] The lignite from Inner Mongolia was dried, crushed, and screened sequentially to obtain 200-mesh fine lignite powder, which was then packaged, sealed, and dried for storage.

[0043] 2. Electrochemical oxidation extraction of humic acid

[0044] Pretreated and refined coal powder and electrolyte were placed in the anode cell of an H-type electrolytic cell, and an equal amount of electrolyte of the same concentration was placed in the cathode cell. Electrochemical oxidation was carried out using a three-electrode system with constant potential. The anode cell was connected to the working electrode and the reference electrode, and the cathode cell was connected to the counter electrode. After the electrochemical reaction was completed, the anode coal slurry was centrifuged. The separated upper layer solution was titrated with an acid solution and allowed to stand. After centrifugation, the solid product was vacuum dried to obtain humic acid. The electrolyte was a 3 mol / L KOH solution, and the ratio of coal powder to electrolyte was 0.6 g: 30 ml. The voltage between the working electrode and the reference electrode was kept constant at 1.2 V. The electrochemical reaction time was 24 h. The stirring rate of the anode cell was 500 rpm / min. The centrifugation speed was 8000 rpm / min, and the centrifugation time was 5 min. The vacuum drying temperature was 80℃, and the time was 12 h.

[0045] 3. High-temperature catalytic pyrolysis

[0046] The humic acid obtained in step 2 was ground into powder and mixed with iron salt catalyst at a mass ratio of 1:1.5. The mixture was then impregnated and stirred in deionized water at a solid-liquid ratio of 1:2. The impregnated mixture was dried in a forced-air drying oven and then ground and sieved to obtain humic acid-derived porous carbon adsorbent material.

[0047] Example 2

[0048] This embodiment uses low-rank coal powder as raw material and employs an electrochemical oxidation method to extract humic acid from lignite, followed by high-temperature catalytic pyrolysis to prepare humic acid-derived porous carbon adsorbent materials. The method is carried out according to the following steps:

[0049] 1. Raw material pretreatment

[0050] The lignite from Inner Mongolia was dried, crushed, and screened sequentially to obtain 200-mesh fine lignite powder, which was then packaged, sealed, and dried for storage.

[0051] 2. Electrochemical oxidation extraction of humic acid

[0052] Pretreated and refined coal powder and electrolyte were placed in the anode cell of an H-type electrolytic cell, and an equal amount of electrolyte of the same concentration was placed in the cathode cell. Electrochemical oxidation was carried out using a three-electrode system with constant potential. The anode cell was connected to the working electrode and the reference electrode, and the cathode cell was connected to the counter electrode. After the electrochemical reaction was completed, the anode coal slurry was centrifuged. The separated upper layer solution was titrated with an acid solution and allowed to stand. After centrifugation, the solid product was vacuum dried to obtain humic acid. The electrolyte was a 1 mol / L KOH solution, and the ratio of coal powder to electrolyte was 0.6 g: 30 ml. The voltage between the working electrode and the reference electrode was constant at 1.0 V. The electrochemical reaction time was 12 h. The stirring rate of the anode cell was 500 rpm / min. The centrifugation speed was 8000 rpm / min, and the centrifugation time was 5 min. The vacuum drying temperature was 80℃, and the time was 12 h.

[0053] 3. High-temperature catalytic pyrolysis

[0054] The humic acid obtained in step 2 was ground into powder and mixed with the iron salt catalyst potassium ferrate at a mass ratio of 1:1.5. The mixture was then impregnated and stirred in deionized water at a solid-liquid ratio of 1:2. The impregnated mixture was dried in a forced-air drying oven and then ground and sieved to obtain humic acid-derived porous carbon adsorbent material.

[0055] Adsorption performance test

[0056] 1. The humic acid-derived porous carbon adsorbent material obtained in steps 1-3 of Example 1 was used as an adsorbent for heavy metal ions, and its adsorption performance was tested:

[0057] Prepare a Pb solution with a mass concentration of 500 mg / L. 2+ Cu 2+Co 2+ Ni 2+ The solutions (actual solution concentrations may vary slightly) were pH-calibrated to 5. 10 ml of each solution was taken, and 10 mg of the humic acid-derived porous carbon adsorbent material prepared in this invention was added. The solutions were incubated at 25°C with constant shaking for 12 hours, allowed to stand for a period, and then filtered. The changes in the concentration of each ion in the filtrate before and after adsorption were measured. The adsorption amounts are shown in Table 1.

[0058] Table 1. Adsorption performance of humic acid-derived porous carbon adsorbents for different heavy metal ions.

[0059] metal ions <![CDATA[Pb 2+ ]]> <![CDATA[Cu 2+ ]]> <![CDATA[Co 2+ ]]> <![CDATA[Ni 2+ ]]> Adsorption capacity (mg / g) 539.4 256.2 176 130.7

[0060] Based on Table 1 Figure 6 It can be seen that Example 1 has a good adsorption effect on all four ions, with the best adsorption effect on lead ions, reaching 99.7%, which is almost complete adsorption.

[0061] 500 mg / ml Pb 2+ The solution could be completely aspirated, so a further 1000 mg / ml Pb solution was prepared. 2+ The solution, using the humic acid-derived porous carbon adsorbent obtained in steps 1-3 of Example 1 as an adsorbent for heavy metal ions, was subjected to adsorption performance testing:

[0062] Prepare a Pb solution with a mass concentration of 1000 mg / L. 2+ The solution, with a pH of 5, was prepared by measuring 10 ml of Pb. 2+ Then, 10 mg of the humic acid-derived porous carbon adsorbent material prepared in this invention was added to the solution, and the mixture was kept at 25°C and shaken for 12 hours. After standing for a period of time, it was filtered, and the Pb content in the solution before and after adsorption was measured. 2+ Concentration change. Pb was measured. 2+ The adsorption capacity can reach 850 mg / g, and the adsorption rate can reach 83.1%.

[0063] Figure 2 The XRD curve of the humic acid-derived porous carbon adsorbent material obtained in Example 1 shows that after pyrolysis with iron salt, zero-valent iron and iron carbide are generated.

[0064] Figure 3 The nitrogen adsorption-desorption isotherm curves obtained from the humic acid-derived porous carbon adsorbent material in Example 1 are shown. The isotherm adsorption curves show that they are typical type I / IV adsorption isotherms with obvious "hysteresis loops". The material has microporous and mesoporous structures and a specific surface area of ​​96.67 m2 / g.

[0065] Figure 4The figure shows the pore size distribution curve of the humic acid-derived porous carbon adsorbent material obtained in Example 1. It can be seen from the figure that the pore size distribution is mainly micropores and mesopores, which further confirms the feasibility of the metal catalytic preparation process.

[0066] Figure 5 , Figure 6 The humic acid-derived porous carbon adsorbent material obtained in Example 1 is used for Cu 2+ Co 2+ Ni 2+ Pb 2+ Adsorption effects of four heavy metal ions. The figure shows that the humic acid-derived porous carbon adsorbent material has good adsorption effects on all four ions, with particularly good adsorption of Pb. 2+ The adsorption effect was optimal, with an adsorption capacity of 539.4 mg / g for 500 mg / L Pb. 2+ The solution adsorption rate reached 99.7%.

[0067] 2. The humic acid-derived porous carbon adsorbent material obtained in steps 1-3 of Example 2 was used as an adsorbent for heavy metal ions, and its adsorption performance was tested.

[0068] Prepare a Pb solution with a mass concentration of 500 mg / L. 2+ Cu 2+ Co 2+ Ni 2+ The solutions (actual solution concentrations may vary slightly) were pH-calibrated to 5. 10 ml of each solution was taken, and 10 mg of the humic acid-derived porous carbon adsorbent material prepared in this invention was added. The solutions were incubated at 25°C with constant shaking for 12 hours, allowed to stand for a period, and then filtered. The changes in the concentration of each ion in the filtrate before and after adsorption were measured. The adsorption amounts are shown in Table 2.

[0069] Table 2 Adsorption performance of humic acid-derived porous carbon adsorbents for different heavy metal ions

[0070] metal ions <![CDATA[Pb 2+ ]]> <![CDATA[Cu 2+ ]]> <![CDATA[Co 2+ ]]> <![CDATA[Ni 2+ ]]> Adsorption capacity (mg / g) 510.2 234.5 165.2 121.3

[0071] As can be seen from Table 2, the humic acid-derived porous carbon adsorbent material obtained in Example 2 has a good adsorption effect on the four ions, among which the adsorption effect on lead ions is the best, reaching 99.8%, which is almost complete adsorption.

[0072] Therefore, this invention employs an electrochemical method for refining humic acid to prepare derived porous carbon adsorbent materials. By simplifying the humic acid extraction process, the oxidation and alkali dissolution processes are completed in one step, significantly increasing the humic acid yield to over 73%. Compared with traditional humic acid extraction processes, this method is simpler, has easier-to-control reaction conditions, and is pollution-free. Combined with the abundant availability and low cost of raw materials, it has great potential for large-scale production. Using the extracted humic acid as a raw material, porous carbon adsorbent materials with a porous structure were synthesized with a metal catalyst in a closed environment. Applied to the adsorption of heavy metal ions, these materials exhibited excellent adsorption performance. This provides an application basis for the large-scale preparation and application of porous carbon adsorbent materials, and also offers new ideas for the resource utilization, efficient, and high-value-added utilization of low-rank coal, further broadening its application value.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing derived porous carbon adsorbent materials by electrochemical extraction of humic acid for heavy metal ion adsorption, comprising extracting humic acid by electrochemical oxidation of low-rank coal and preparing humic acid-derived porous carbon adsorbent materials by high-temperature catalytic pyrolysis, characterized in that: Includes the following steps: Step 1: Low-rank coal is crushed, ball-milled, and sieved; coal powder sample is weighed and added to the anode area of ​​H-type electrolytic cell, alkaline solution is added, and the mixture is stirred to make a uniform coal slurry; Step 2: The experiment was conducted using the H-type electrolytic cell from Step 1, with the anode region containing low-rank coal slurry and the cathode region containing an equal volume and concentration of alkaline solution. A three-electrode system was used, with the anode as the working electrode and the cathode as the counter electrode. The anode was stirred during the reaction, and the voltage, electrochemical reaction time, and alkaline solution concentration were controlled as variables. The experiment was conducted using the constant potential method under normal temperature and pressure. Step 3: After the electrochemical reaction is completed, the anode coal slurry after the reaction in Step 2 is centrifuged. The upper layer solution obtained by separation is titrated with acid solution to pH=1-2. After standing for 1 hour, it is centrifuged again. The solid product obtained is vacuum dried to obtain humic acid. The acid solution in step three is a mixed acid, which includes nitric acid and phosphoric acid, wherein the volume ratio of nitric acid to phosphoric acid is 1-2:3-5, the concentration of nitric acid is 2-5 mol / L, and the concentration of phosphoric acid is 5-15 mol / L. Step 4: Grind the humic acid obtained in Step 3 into powder, mix it with the metal catalyst at different mass ratios to obtain a mixed sample, impregnate the mixed sample in deionized water at a certain solid-liquid ratio and stir the mixture, then dry the impregnated mixture in a forced-air drying oven, grind and sieve it after drying to obtain a uniform mixture, and finally pyrolyze the dried mixture at high temperature to obtain the final humic acid-derived porous carbon adsorbent material. The metal catalyst in step four is potassium ferrate, and the mass ratio of humic acid powder to metal catalyst is 1:0.25-1.

5.

2. The method for preparing derived porous carbon adsorbent materials by electrochemical extraction of humic acid for heavy metal ion adsorption according to claim 1, characterized in that: The concentration of the alkaline solution in step one is 0.5-3 mol / L.

3. The method for preparing derived porous carbon adsorbent materials by electrochemical extraction of humic acid for heavy metal ion adsorption according to claim 1, characterized in that: In step two, the anode stirring speed is 100-800 r / min, the voltage of the working electrode relative to the reference electrode is 0.4-2V, and the electrochemical reaction time is 1-24h.

4. The method for preparing derived porous carbon adsorbent materials by electrochemical extraction of humic acid for heavy metal ion adsorption according to claim 1, characterized in that: In step three, the centrifugation separation step is set with a centrifuge speed of 3000-8000 rad / min and a centrifugation time of 3-10 min.

5. The method for preparing derived porous carbon adsorbent materials by electrochemical extraction of humic acid for heavy metal ion adsorption according to claim 1, characterized in that: The vacuum drying conditions in step three are a vacuum oven at 60-80℃ and a drying time of 12-24 hours.

6. The method for preparing derived porous carbon adsorbent materials by electrochemical extraction of humic acid for heavy metal ion adsorption according to claim 1, characterized in that: In step four, the solid-liquid ratio of the mixed sample to deionized water is 1:2-5, the stirring time is 8-24 hours, and the drying conditions are a forced-air drying oven at 80-110℃.

7. The method for preparing derived porous carbon adsorbent materials by electrochemical extraction of humic acid for heavy metal ion adsorption according to claim 1, characterized in that: The high-temperature pyrolysis in step four is 600-900℃, and pyrolysis is carried out in a tube furnace with a heating rate of 2-5℃ / min and a holding time of 2-5h.

8. An electrochemical method for refining humic acid from low-rank coal and its derived porous carbon, and its application in the adsorption of heavy metal ions.

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