Preparation of modified sludge / coal co-pyrolysis porous carbon and PS-AOPs treatment process of phenol wastewater
By combining nitrogen- and iron-doped sludge/coal co-pyrolysis porous carbon materials with deep oxidation technology, the problems of low adsorption rate of sludge-based porous carbon and iron sludge pollution in advanced oxidation processes were solved, achieving efficient and low-cost deep treatment of phenol wastewater, reaching a phenol degradation rate of more than 96% and easy separation and recovery.
Patent Information
- Application Number
- CN202511029991.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-25
- Publication Date
- 2025-10-17
AI Technical Summary
In existing technologies, the adsorption rate of phenol by sludge-based porous carbon is low, and the powdered material is difficult to separate, leading to secondary pollution. In addition, advanced oxidation processes such as the PDS/Fe²⁺ system require the continuous addition of iron salts to produce iron sludge pollution, which has high treatment costs and makes it difficult to achieve low-cost and efficient deep treatment of phenol wastewater.
By co-pyrolyzing porous carbon materials with sludge/coal doped with nitrogen and iron elements and combining them with deep oxidation technology, nitrogen doping introduces alkaline sites, and iron species activate persulfate to produce sulfate radicals, achieving synergistic effects and achieving efficient degradation of phenol in phenol wastewater.
The phenol degradation rate in phenol wastewater reaches more than 96%, preferably 98.2%, and the material is easy to separate and recycle, which reduces the treatment cost and improves the treatment efficiency and environmental friendliness.
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Figure CN120790201A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of adsorption materials and water treatment, and specifically relates to a method for preparing modified sludge / coal co-pyrolysis porous carbon and a PS-AOPs deep treatment process for phenol wastewater using the modified porous carbon material in combination with deep oxidation technology. Background Art
[0002] In recent years, with the rapid development of urbanization, the number of urban sewage treatment plants has skyrocketed. However, while these improvements have posed a new challenge, the need for massive sludge disposal has emerged. Currently, sludge treatment methods in my country include sanitary landfill, incineration, building material utilization, land use, and stockpiling, all of which inevitably cause secondary environmental damage. Research has shown that dewatered sludge can contain 35%-55% organic matter and a calorific value of approximately 8-12 MJ / kg. However, due to its high degree of dispersion and diverse properties, its conversion and utilization alone is difficult. On the other hand, my country has abundant reserves of low-rank coal, and the technology for forming and pyrolyzing low-rank coal is relatively mature. Co-pyrolysis of sludge and low-rank coal to produce porous carbon, and using this porous carbon material as a wastewater treatment adsorbent, can not only fully utilize the organic matter and calorific value of dewatered sludge, reducing fossil energy consumption, but also avoiding the formation of secondary waste. This allows for the clean and efficient utilization of sludge and low-rank coal, with promising economic, social, and ecological benefits.
[0003] Phenol, a major organic pollutant in industrial wastewater, is high in concentration, difficult to degrade, highly toxic, and carcinogenic, causing persistent damage and impact on the environment. While porous carbon prepared by the co-pyrolysis of sludge and low-rank coal has been used as an adsorbent to treat phenol wastewater, while cost-effective, the adsorption rate of phenol by sludge-based porous carbon is typically less than 60%, and the powdered material is difficult to separate, leading to secondary pollution. Advanced oxidation processes (such as the PDS / Fe²⁺ system) can also treat phenol wastewater, but they require the continuous addition of iron salts, resulting in iron sludge contamination. Therefore, developing a low-cost, high-efficiency deep treatment process for phenol wastewater using porous carbon prepared by the co-pyrolysis of sludge and low-rank coal is of great significance for environmental protection and human health. Summary of the Invention
[0004] In order to solve the problems of incomplete pollutant removal, high treatment cost and difficulty in industrial conversion in phenol wastewater treatment methods, the present invention provides a method for preparing modified sludge / coal co-pyrolysis porous carbon and a PS-AOPs treatment process for phenol wastewater using the modified porous carbon material in combination with deep oxidation technology.
[0005] The mechanism of the present application is that after doping nitrogen and iron elements in the porous carbon structure of sludge / coal co-pyrolysis, combined with the deep oxidation technology, the alkaline sites introduced by nitrogen doping promote the dissociation of PMS, and the iron species (Fe2+ / Fe3+) activate PMS through valence state cycle to generate sulfate radicals (SO4·-), and the two synergistically enhance the degradation rate of phenol in phenol wastewater to more than 96%, and in the preferred embodiment, it can reach 98.2%.
[0006] The technical scheme adopted by the present application to achieve the above-mentioned purpose is as follows.
[0007] A preparation method of a modified sludge / coal co-pyrolysis porous carbon material, comprising the following steps: Step 1, drying the municipal sludge at 100-110℃ for 45-55 h, crushing and sieving through a 200 mesh screen to obtain pretreated municipal sludge; Step 2, under an inert atmosphere, mixing the pretreated municipal sludge and low-rank coal powder uniformly according to a mass ratio of 1:1, and then co-pyrolyzing at 750-850℃ for 90-180 min to obtain a co-pyrolysis product; Step 3, mixing the co-pyrolysis product with KOH according to a mass ratio of 1:2, adding water, stirring magnetically for 3-6 h, drying, and then mixing with a nitrogen source and an iron source according to a mass ratio of 1:3:4.7, impregnating for 12 h, and drying to obtain an N, Fe element doped precursor; Step 4, calcining the N, Fe element doped precursor in an inert atmosphere at 750-850℃ for 90-180 min to obtain a modified sludge / coal co-pyrolysis porous carbon material.
[0008] The municipal sludge has a high water content, and the biochar formed by direct pyrolysis has poor microstructure and surface chemical properties. By the treatment method of drying and sieving, on the one hand, the water content of the sludge is reduced, and on the other hand, the particle size of the sludge is reduced, which is beneficial to the formation of small-sized co-pyrolysis products by co-pyrolysis, and the smaller the size of the sludge, the larger the specific surface area, which is beneficial to increasing the contact area between the sludge / coal co-pyrolysis porous carbon material and the persulfate, thereby deep synergistic effect occurs.
[0009] Preferably, the nitrogen source in step 3 is selected from any one of melamine, urea, and nitric acid, and the iron source is selected from any one of FeCl3·6H2O, FeCl2·4H2O, or ferric nitrate.
[0010] Preferably, after KOH activation in step 3, a step of pre-calcining at 600℃ for 1 h in nitrogen is further included.
[0011] Preferably, the heating rate of high-temperature calcination in step 4 is 5-10℃ / min.
[0012] Preferably, the inert atmosphere is in a nitrogen / argon atmosphere.
[0013] The modified sludge / coal co-pyrolysis porous carbon material is characterized in that the modified sludge / coal co-pyrolysis porous carbon material has an irregular layered structure, a specific surface area of greater than or equal to 130 m² / g, a mesopore area of greater than or equal to 30 m² / g, a pore volume of greater than or equal to 0.08 cm³ / g, and a saturation magnetization of greater than or equal to 5 emu / g.
[0014] The present application also relates to a PS-AOPs treatment process for phenol wastewater, which uses the modified sludge / coal co-pyrolysis porous carbon material and a persulfate salt. a) adjusting the pH of the phenol wastewater to 4-11; b) adding the modified porous carbon material at 0.2-0.5 g / L and the persulfate salt at 0.06-0.45 g / L; c) magnetically separating and recovering the catalyst after the reaction.
[0015] Preferably, the persulfate salt is peroxymonosulfate.
[0016] Preferably, the modified sludge / coal co-pyrolysis porous carbon material is added at 0.2-0.5 g / L of wastewater, and the persulfate salt is added at 0.5-0.7 g / L of wastewater.
[0017] Preferably, the phenol concentration of the phenol wastewater is 5-30 ppm, and the phenol removal rate is greater than or equal to 97.5%.
[0018] Compared with the prior art, the present application has the following technical progress: (1) The present application provides a modified sludge / coal co-pyrolysis porous carbon material with rich pore structure, good electrical performance and easy separation and recovery, and the preparation method is simple, easy to operate and low in cost, which not only solves the problem of sludge treatment and disposal in municipal wastewater treatment plants, but also improves the utilization value of low-rank coal, and has good environmental and economic benefits.
[0019] (2) The present application uses sludge and low-rank coal with low utilization value to prepare porous carbon material, which reduces the preparation cost of the adsorption material, and uses the modified sludge / coal co-pyrolysis porous carbon material and the advanced oxidation technology for the advanced phenol removal treatment of phenol wastewater, the modified sludge / coal co-pyrolysis porous carbon material has a certain physical adsorption effect on one hand, and a catalytic activation effect on the other hand, so that the phenol adsorbed on the surface is more easily further oxidized under the action of the activated persulfate salt, and is converted into degradation products that are easy to separate and remove, which has the advantages of high removal efficiency and fast degradation speed.
[0020] (3) Since the modified sludge / coal co-pyrolysis porous carbon material has certain magnetic properties, it can also be recovered by magnetic adsorption separation technology, which solves the technical problem of the difficulty in separating powdered adsorption materials after using activated carbon and other adsorption materials alone to treat wastewater in the existing technology. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 Field emission scanning electron microscope morphology images of sludge / coal co-pyrolysis products and the modified sludge / coal co-pyrolysis porous carbon material of the present invention; Figure 2 Fourier transform infrared spectra of sludge-coal co-pyrolysis biochar and N / Fe co-doped biochar.
[0022] Figure 3 Electrochemical impedance spectroscopy of sludge-coal co-pyrolysis biochar and N / Fe co-doped biochar.
[0023] Figure 4 The removal effects of phenol by PMS alone, N / Fe co-doped biochar alone, sludge-coal co-pyrolysis biochar combined with PMS, and N / Fe co-doped biochar combined with PMS are shown in the figure. Figure 5 This is the removal effect of phenol by nitrogen / iron co-doped biochar N / Fe-BCs activated with PMS at different pH values; Figure 6 Figure 3. The removal effect of phenol on PMS activated by nitrogen / iron co-doped biochar N / Fe-BCs prepared under different conditions. DETAILED DESCRIPTION
[0024] The specific embodiments of the present invention will be further described below in conjunction with examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Various changes, modifications, substitutions and variations made by those skilled in the art without departing from the principles and purpose of the present invention to these examples should all be included within the scope of protection of the present invention.
[0025] Example 1
[0026] A method for preparing a modified sludge / coal co-pyrolysis porous carbon material comprises the following steps:
[0027] Step 1: Municipal sludge is taken from dewatered sludge and placed in an oven at 105° C. for 48 hours to obtain dried municipal sludge; the dried municipal sludge is then ground in a mortar and passed through a 200-mesh polyethylene sieve to obtain pretreated municipal sludge; low-rank coal is then ground in a mortar and passed through a 200-mesh polyethylene sieve to obtain pretreated low-rank coal powder.
[0028] Step 2, the pretreated municipal sludge and the pretreated low-rank coal powder with a mass ratio of 1:1 were uniformly mechanically stirred, and were placed in a tubular furnace. Nitrogen was first passed for 20 min to ensure an inert atmosphere in the tubular furnace. Then the tubular furnace was heated to 800℃ at a heating rate of 10℃ / min, and pyrolysis was carried out for 120 min. After cooling, the sludge / coal co-pyrolysis product was obtained.
[0029] Step 3, in a three-necked flask, the KOH and the sludge / coal co-pyrolysis product prepared in Example 1 with a mass ratio of 2:1 were ultrasonically dispersed in H2O with water as the solvent and KOH as the pore-expanding agent. After magnetic stirring for 4 h, the activated co-pyrolysis product was obtained by washing and drying. Then, the activated co-pyrolysis product, urea, FeCl3·6 H2O and FeCl2·4 H2O with a mass ratio of 1:3:2.35:2.35 were ultrasonically dispersed in H2O at room temperature with urea as the N element dopant and FeCl3·6 H2O and FeCl2·4 H2O as the Fe element dopant. After magnetic stirring for 12 h, the product was washed and dried.
[0030] Step 4, the N and Fe element doped and modified activated pyrolysis product obtained in Step 3 was subjected to high-temperature calcination in a high-temperature tubular furnace under an inert atmosphere. The heating rate was 10℃ / min, and the temperature was 800℃ under an inert atmosphere. The time was 2 h. The modified sludge / coal co-pyrolysis porous carbon material was obtained, which was labeled as N / Fe-BCs-1.
[0031] Comparative Example 1
[0032] As a comparison, a non-modified sludge / coal co-pyrolysis porous carbon material was prepared in Comparative Example 1. In the preparation method of Example 1, Step 3 was omitted, and the sludge / coal co-pyrolysis product prepared in Step 2 was directly subjected to secondary high-temperature calcination in Step 4 to obtain the non-modified sludge / coal co-pyrolysis porous carbon material, which was labeled as BCs-1.
[0033] Figure 1 The field emission scanning electron microscope images of the sludge / coal co-pyrolysis product and the modified sludge / coal co-pyrolysis porous carbon material prepared above are shown in Figures a and b. It can be seen from the comparison that the morphology of the sludge / coal co-pyrolysis product is relatively regular and arranged densely. After KOH activation and N / Fe element doping, the morphology presents an irregular layered structure, and the material becomes more porous. The mesoporous structure increases the specific surface area of the modified sludge / coal co-pyrolysis porous carbon material, so that more persulfate and organic pollutants in wastewater can be loaded and adsorbed, and the effect of catalytic persulfate on removing organic pollutants in water is improved.
[0034] Example 2
[0035] A preparation method of modified sludge / coal co-pyrolysis porous carbon material, comprising the following steps:
[0036] Step 1, municipal sludge is taken from dewatered sludge and placed in an oven at 100℃ for 55h to obtain dried municipal sludge; then the dried municipal sludge is ground with a mortar and sieved through a 200-mesh polyethylene screen to obtain pretreated municipal sludge; then low-rank coal is ground with a mortar and sieved through a 200-mesh polyethylene screen to obtain pretreated low-rank coal powder.
[0037] Step 2, pretreated municipal sludge and pretreated low-rank coal powder with a mass ratio of 1:1 are uniformly mechanically stirred and placed in a tube furnace; nitrogen gas is passed for 20 min to ensure an inert atmosphere in the tube furnace; the tube furnace is heated to 750℃ at a heating rate of 10℃ / min and pyrolyzed for 180 min; after cooling, a sludge / coal co-pyrolysis product is obtained.
[0038] Step 3, in a three-necked flask at room temperature, KOH and the sludge / low-rank coal co-pyrolysis product prepared in Example 1 are ultrasonically dispersed in H2O with a mass ratio of 2:1; after magnetic stirring for 4h, the mixture is washed and dried to obtain an activated co-pyrolysis product; then urea is used as an N element dopant and FeCl3·6 H2O and FeCl2·4 H2O are used as Fe element dopants (with a mass ratio of 2.7:2); the activated co-pyrolysis product, urea, FeCl3·6 H2O and FeCl2·4 H2O are ultrasonically dispersed in H2O with a mass ratio of 1:3:2.7:2 at room temperature; after magnetic stirring for 12h, the mixture is washed and dried.
[0039] Step 4, the N and Fe element doped and modified activated pyrolysis product obtained in step 3 is subjected to high-temperature calcination in a high-temperature tube furnace under an inert atmosphere; the heating rate is 10℃ / min; the temperature is 850℃ under an inert atmosphere; the time is 1.5h; a modified sludge / coal co-pyrolysis porous carbon material is obtained, which is labeled as N / Fe-BCs-2.
[0040] Comparative Example 2
[0041] As a comparison, a non-modified sludge / coal co-pyrolysis porous carbon material is prepared in Comparative Example 2, i.e. step 3 in Example 2 is omitted; the sludge / coal co-pyrolysis product obtained in step 2 is directly subjected to secondary high-temperature calcination in step 4; a non-modified sludge / coal co-pyrolysis porous carbon material is obtained, which is labeled as BCs-2.
[0042] Figure 2The Fourier infrared spectrum images of the modified sludge / coal co-pyrolysis porous carbon material prepared by the above method and the unmodified sludge / coal co-pyrolysis porous carbon material. It can be seen by comparison that the BCs surface contains rich functional group structures such as -OH, -C-O, -C=O, -CH, etc. After N, Fe doping, nitrogen and iron functional groups -NH and Fe-O appear in N / Fe-BCs, indicating the successful doping of N and Fe elements, and significantly improving the effect of activated biochar material on the degradation of organic pollutants by persulfate.
[0043] Example 3
[0044] A preparation method of a modified sludge / coal co-pyrolysis porous carbon material, comprising the following steps:
[0045] Step 1, municipal sludge is taken from dewatered sludge and placed in an oven at 110°C for 45h to obtain dried municipal sludge; then the dried municipal sludge is ground with a mortar and sieved through a 200-mesh polyethylene screen to obtain pretreated municipal sludge; then low-rank coal is ground with a mortar and sieved through a 200-mesh polyethylene screen to obtain pretreated low-rank coal powder.
[0046] Step 2, pretreated municipal sludge and pretreated low-rank coal powder with a mass ratio of 1:1 are uniformly mechanically stirred and placed in a tube furnace; first, nitrogen gas is passed for 20 min to ensure an inert atmosphere in the tube furnace; then the tube furnace is raised to 850°C at a heating rate of 10°C / min and pyrolyzed for 90 min; after cooling, a sludge / coal co-pyrolysis product is obtained.
[0047] Step 3, in a three-necked flask at room temperature, KOH and the municipal sludge / low-rank coal co-pyrolysis product prepared in Example 1 are ultrasonically dispersed in H2O with a mass ratio of 2:1, and magnetically stirred for 4 h; after washing and drying, an activated co-pyrolysis product is obtained; then urea is used as an N element dopant, FeCl3·6 H2O and FeCl2·4 H2O are used as Fe element dopants (mass ratio of 2.7:2), and the activated co-pyrolysis product, urea, FeCl3·6 H2O and FeCl2·4 H2O are ultrasonically dispersed in H2O with a mass ratio of 1:3:2.7:2 at room temperature; after magnetically stirring for 12 h, washing and drying are performed.
[0048] Step 4, the N, Fe element doped and modified activated pyrolysis product obtained in Step 3 is subjected to high-temperature calcination in a high-temperature tube furnace under an inert atmosphere, with a heating rate of 10°C / min; under an inert atmosphere, the temperature is 750°C and the time is 2.5 h; a modified sludge / coal co-pyrolysis porous carbon material is obtained, labeled as N / Fe-BCs-3.
[0049] Figure 3Figure 2 shows the electrochemical impedance spectroscopy (EIS) of the modified and unmodified porous carbon materials prepared by the aforementioned method. Comparison shows that the BCs exhibit a larger semicircular diameter, indicating lower conductivity. In contrast, the N / Fe-BCs exhibit a smaller diameter and significantly lower electrode resistance, demonstrating excellent conductivity, accelerated electron transfer, and enhanced the biochar's ability to activate persulfate to degrade organic pollutants.
[0050] The following Examples 4 to 6 further illustrate the process of using the modified sludge / coal co-pyrolysis porous carbon material prepared in Examples 1 to 3 in combination with potassium persulfate to eliminate phenol.
[0051] Example 4
[0052] 0.4 g of modified sludge / coal co-pyrolysis porous carbon material N / Fe-BCs-1 and 0.62 g of potassium persulfate were added to 1 L of phenol wastewater with a concentration of 20 ppm. The pH of the phenol wastewater was adjusted to 6.5, and then placed in a magnetic stirrer for reaction. Samples were taken at 0, 5, 10, 20, 30, 60, 90 and 120 min, and the degradation of the organic pollutant phenol was analyzed. The results are shown in Figure 2. Figure 4 .Depend on Figure 4 It can be seen that the phenol removal rate of the N / Fe-BCs-1+PMS system reached 98.2% within 120 min (only 78.5% for the BCs+PMS system).
[0053] After treatment, the N / Fe-BCs-1 catalyst was separated by adsorption using a neodymium magnet, washed three times with deionized water, and dried at 60°C. After three cycles, the phenol removal rate was still >92%.
[0054] Comparative Example 3
[0055] 0.4 g of modified sludge / coal co-pyrolysis porous carbon material was added to 1 L of phenol wastewater with a concentration of 20 ppm, and the reaction was carried out in a magnetic stirrer. Samples were taken at 0, 5, 10, 20, 30, 60, 90 and 120 min, and the degradation of the organic pollutant phenol was analyzed. The results are shown in Figure 2. Figure 4 .Depend on Figure 4 It can be seen that the phenol removal rate of the system with only N / Fe-BCs-1 added was only about 10% within 120 min.
[0056] Comparative Example 4
[0057] 0.62g of potassium persulfate was added to 1L of phenol wastewater with a concentration of 20 ppm, and the mixture was placed in a magnetic stirrer for reaction. Samples were taken at 0, 5, 10, 20, 30, 60, 90 and 120 min, and the degradation of the organic pollutant phenol was analyzed. The results are shown in Figure 2. Figure 4 .Depend onFigure 4 It can be seen that the system only adding PMS (potassium hydrogen persulfate) has almost 0 phenol removal rate within 120 min.
[0058] Comparative Example 5
[0059] 0.4 g of unmodified sludge / coal co-pyrolysis porous carbon material and 0.62 g of potassium hydrogen persulfate were added to 1 L of phenol wastewater with a concentration of 20 ppm, and placed in a magnetic stirrer reaction. Samples were taken at 0, 5, 10, 20, 30, 60, 90 and 120 min, respectively, and the degradation of the organic pollutant phenol was analyzed. The results are shown in Table 4. Figure 4 It can be seen that the system only adding PMS (potassium hydrogen persulfate) has almost 0 phenol removal rate within 120 min. Figure 4 It can be seen that the system only adding PMS (potassium hydrogen persulfate) has almost 0 phenol removal rate within 120 min.
[0060] After the reaction was completed, the N / Fe-BCs catalyst was recovered by magnetic adsorption and recycled after regeneration.
[0061] Example 5
[0062] 0.4 g of unmodified sludge / coal co-pyrolysis porous carbon material and 0.62 g of potassium hydrogen persulfate were added to 1 L of phenol wastewater with a concentration of 20 ppm, and placed in a magnetic stirrer reaction. Samples were taken at 0, 5, 10, 20, 30, 60, 90 and 120 min, respectively, and the degradation of the organic pollutant phenol was analyzed. The results are shown in Table 4. Figure 5 .
[0063] Figure 5 The results show that the phenol removal rate of the phenol wastewater PS-AOPs treatment process using the modified sludge / coal co-pyrolysis porous carbon material and the advanced oxidation technology is close to 100% in both weakly acidic and neutral solutions. It is shown that the treatment process of the present application has little change with the pH value of the phenol wastewater, and has good acid-base stability and applicability.
[0064] Example 6
[0065] 0.4 g of unmodified sludge / coal co-pyrolysis porous carbon material and 0.62 g of potassium hydrogen persulfate were added to 1 L of phenol wastewater with a concentration of 20 ppm, and placed in a magnetic stirrer reaction. Samples were taken at 0, 5, 10, 20, 30, 60, 90 and 120 min, respectively, and the degradation of the organic pollutant phenol was analyzed. The results are shown in Table 4. Figure 6 . Figure 6The results show that the phenol wastewater PS-AOPs treatment process adopting the modified sludge / coal co-pyrolysis porous carbon material and the deep oxidation technology combined process has the phenol removal rate of more than 85.0% in 90 min, and the phenol removal rate of three kinds of N / Fe-BCs catalysts is more than 97% in 120 min when the treatment time is 120 min, and the saturation magnetization is 8.5-12.3 emu / g.
[0066] After the reaction is completed, the N / Fe-BCs catalyst is recovered by a magnet, and after regeneration, the N / Fe-BCs catalyst is recycled for three times, and the phenol removal rate is still more than 90%.
Claims
1. A method for preparing a modified sludge / coal co-pyrolysis porous carbon material, comprising the following steps: Step 1, drying the municipal sludge at 100-110° C. for 45-55 hours, crushing it, and passing it through a 200-mesh sieve to obtain pretreated municipal sludge; Step 2: Under an inert atmosphere, the pretreated municipal sludge and low-rank coal powder are uniformly mixed in a mass ratio of 1:1, and then co-pyrolyzed at 750-850° C. for 90-180 min to obtain a co-pyrolysis product; Step 3: The co-pyrolysis product is mixed with KOH in a mass ratio of 1:2, and water is added and magnetically stirred for 3-6 hours, followed by drying. The mixture is then mixed with a nitrogen source and an iron source in a mass ratio of 1:3:4.7 and impregnated for 12 hours, followed by drying to obtain a N and Fe element-doped precursor. Step 4: calcine the N and Fe element-doped precursor in an inert atmosphere at 750-850° C. for 90-180 min to obtain a modified sludge / coal co-pyrolysis porous carbon material.
2. The preparation method according to claim 1, wherein In step 3, the nitrogen source is selected from any one of melamine, urea, and nitric acid, and the iron source is selected from any one of FeCl3·6H2O, FeCl2·4H2O, or ferric nitrate.
3. The preparation method according to claim 1, wherein After KOH activation in step 3, the method further includes pre-calcining at 600° C. in nitrogen for 1 h.
4. The preparation method according to claim 1, wherein The heating rate of high temperature calcination in step 4 is 5-10°C / min.
5. The preparation method according to claim 1, wherein The inert atmosphere was under nitrogen / argon atmosphere.
6. A modified sludge / coal co-pyrolysis porous carbon material, prepared by the preparation method according to any one of claims 1 to 5, characterized in that: The modified sludge / coal co-pyrolysis porous carbon material has an irregular layered structure, a specific surface area of ≥130 m² / g, a mesopore area of ≥30 m² / g, a pore volume of ≥0.08 cm³ / g, and a saturation magnetization of ≥5 emu / g.
7. A PS-AOPs treatment process for phenol wastewater, characterized in that: The modified sludge / coal co-pyrolysis porous carbon material according to claim 6 is used in combination with persulfate, comprising: a) Adjust the pH of phenol wastewater to 4-11; b) Add modified porous carbon material at 0.2-0.5 g / L and persulfate at 0.5-0.7 g / L; c) After the reaction, the catalyst is recovered by magnetic separation.
8. The PS-AOPs treatment process for phenol wastewater according to claim 7, wherein: The persulfate is hydrogen persulfate.
9. The PS-AOPs treatment process for phenol wastewater according to claim 7 or 8, characterized in that: The dosage of the modified sludge / coal co-pyrolysis porous carbon material is 0.2g-0.5g per liter of sewage, and the dosage of persulfate is 0.5g-0.7g per liter of sewage.
10. The PS-AOPs treatment process for phenol wastewater according to claim 9, characterized in that: The phenol concentration of the phenol wastewater is 5 ppm to 30 ppm, and the phenol removal rate is ≥97.5%.