Sulfur-doped coal-based activated carbon and preparation method thereof

Abstract

The invention belongs to the technical field of environmental functional materials, and particularly relates to sulfur-doped coal-based activated carbon and a preparation method thereof. The preparation method of the sulfur-doped coal-based activated carbon comprises the following steps: mixing coal-based activated carbon and a sulfur source to obtain mixed powder; calcining the mixed powder to obtain an initial product; and washing the initial product with water and ethanol in sequence to obtain the sulfur-doped coal-based activated carbon. The sulfur-doped coal-based activated carbon has the beneficial effects that pores of the sulfur-doped coal-based activated carbon are developed, sulfur functional groups are rich, and the sulfur-doped coal-based activated carbon has relatively high electrochemical activity; the method is suitable for seawater desalination and brackish water purification scenes; the preparation process of the sulfur-doped coal-based activated carbon is simple, the use of a toxic sulfur source is avoided, and the sulfur-doped coal-based activated carbon is easy for industrial production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of environmental functional materials, and particularly relates to a sulfur-doped coal-based activated carbon and a preparation method thereof. BACKGROUND

[0002] Capacitive deionization (CDI) technology is considered as one of the most promising desalination routes due to its low energy consumption, mild operation and easy modularization. Although traditional activated carbon electrodes have low cost and good electrical conductivity, they have poor ion selectivity and limited desalination capacity. Heteroatom sulfur doping can introduce active sites and improve the selective adsorption of chloride ions. However, existing sulfur doping routes often use high-temperature hydrogen sulfide or sulfur vapor, which is dangerous and polluting. Moreover, the post-treatment washing is simple, and there are a large amount of salts and by-products remaining, which leads to pore blockage and degradation of electrochemical performance. Therefore, it is urgent to develop a green and environmentally friendly sulfur-doped coal-based activated carbon preparation technology with fine post-treatment and excellent electrochemical response. SUMMARY

[0003] The application provides a sulfur-doped coal-based activated carbon and a preparation method thereof, aiming to solve the problems of low matching degree and unknown optimal doping window of existing sulfur-doped coal-based activated carbon.

[0004] The first aspect of the application provides a preparation method of a sulfur-doped coal-based activated carbon, comprising the following steps: (1) mixing coal-based activated carbon and a sulfur source to obtain a mixed powder; (2) calcining the mixed powder to obtain a primary product; (3) washing the primary product with water and ethanol in sequence to obtain the sulfur-doped coal-based activated carbon.

[0005] The sulfur-doped coal-based activated carbon described in the application has developed pores and rich sulfur functional groups, and has high electrochemical activity; and is suitable for seawater desalination and brackish water purification scenes.

[0006] According to some embodiments of the preparation method of the sulfur-doped coal-based activated carbon described in the application, in step (1), the sulfur source is potassium thiosulfate; the specific surface area of the coal-based activated carbon is greater than or equal to 600 m 2 / g, and the particle size D50 is 10-20 μm.

[0007] According to some embodiments of the preparation method of the sulfur-doped coal-based activated carbon described in the application, the mass ratio of the coal-based activated carbon to the sulfur source is 1: (1-3); the mixing is grinding mixing, and the particle size of the mixed powder is 200-300 mesh.

[0008] According to some embodiments of the preparation method of the sulfur-doped coal-based activated carbon provided in the application, in step (2), the temperature of the calcination is 500-700°C, the time of the calcination is 100-140 min; the atmosphere of the calcination is nitrogen atmosphere, and the heating rate of the calcination is 3-8°C / min.

[0009] According to some embodiments of the preparation method of the sulfur-doped coal-based activated carbon provided in the application, in step (3), water washing is performed until the conductivity of the filtrate is less than or equal to 5 μS / cm, and then ethanol washing is performed.

[0010] According to some embodiments of the preparation method of the sulfur-doped coal-based activated carbon provided in the application, the method further comprises a step of preparing a coal-based activated carbon. Specific operation steps include: contacting bituminous coal powder and water vapor to perform activation treatment, thereby obtaining a coal-based activated carbon.

[0011] According to some embodiments of the preparation method of the sulfur-doped coal-based activated carbon provided in the application, water vapor is introduced into the bituminous coal powder, and the activation treatment is performed at a temperature of 700-900°C for 100-150 min; more preferably, the flow rate of the introduced water vapor is 0.4-0.6 mL / min.

[0012] The second aspect of the application provides a sulfur-doped coal-based activated carbon, which is prepared by the preparation method of the first aspect of the application.

[0013] The third aspect of the application provides an electrode comprising the sulfur-doped coal-based activated carbon of the second aspect of the application.

[0014] The fourth aspect of the application provides a capacitive deionization device comprising the electrode of the third aspect of the application.

[0015] According to some embodiments of the capacitive deionization device provided in the application, the capacitive deionization device comprises a device for removing chloride ions or sodium ions.

[0016] The beneficial effects of the application include: the sulfur-doped coal-based activated carbon provided in the application has developed pores and rich sulfur functional groups, and has high electrochemical activity; and is suitable for seawater desalination and brackish water purification scenarios.

[0017] The preparation process of the sulfur-doped coal-based activated carbon provided in the application is simple, avoids the use of toxic sulfur sources, and is easy to industrialize. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1a The SEM image of the sulfur-doped coal-based activated carbon described in Example 1 of the application; Figure 1b The EDS image of the sulfur-doped coal-based activated carbon described in Example 1 of the application; Figure 2aSEM image of the sulfur-doped coal-based activated carbon described in Example 2 of the present application; Figure 2b EDS image of the sulfur-doped coal-based activated carbon described in Example 2 of the present application; Figure 3a SEM image of the sulfur-doped coal-based activated carbon described in Example 3 of the present application; Figure 3b EDS image of the sulfur-doped coal-based activated carbon described in Example 3 of the present application; Figure 4 Left is the cyclic voltammetry (CV) curve of the sulfur-doped coal-based activated carbon described in Example 1 of the present application; Figure 4 Right is the EIS Nyquist plot (frequency 10 kHz-0.01 Hz) of the sulfur-doped coal-based activated carbon described in Example 1 of the present application; Figure 5 Left is the cyclic voltammetry (CV) curve of the sulfur-doped coal-based activated carbon described in Example 4 of the present application; Figure 5 Right is the EIS Nyquist plot (frequency 10 kHz-0.01 Hz) of the sulfur-doped coal-based activated carbon described in Example 4 of the present application; Figure 6 Left is the cyclic voltammetry (CV) curve of the sulfur-doped coal-based activated carbon described in Example 5 of the present application; Figure 6 Right is the EIS Nyquist plot (frequency 10 kHz-0.01 Hz) of the sulfur-doped coal-based activated carbon described in Example 5 of the present application; Figure 7 Desalination capacity test results of the electrode prepared from the sulfur-doped coal-based activated carbon described in Example 1, Example 4-5 at different voltages; Figure 8 Desalination capacity test results of the electrode prepared from the sulfur-doped coal-based activated carbon described in Example 1, Example 3 and Example 6 at different voltages. DETAILED DESCRIPTION

[0019] The embodiments of the present application are described in detail below, and the examples of the embodiments are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0020] In this disclosure, the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" mean that a particular feature, structure, material, or characteristic is included in at least one embodiment or example of the present disclosure. Exemplary representations of the above terms in this specification are not necessarily directed to the same embodiment or example. Moreover, the described particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction, if necessary.

[0021] The embodiments of the present application provide a preparation method of sulfur-doped coal-based activated carbon, comprising the following steps: (1) mixing coal-based activated carbon and sulfur source to obtain mixed powder; (2) calcining the mixed powder to obtain a primary product; (3) washing the primary product with water and ethanol in sequence to obtain the sulfur-doped coal-based activated carbon.

[0022] In some embodiments of the present application, in step (1), the sulfur source comprises potassium thiosulfate. The potassium thiosulfate used in the present application is of analytical purity, and is dried in a vacuum drying oven at 60°C for 4h before use, so that the water content is ≤0.5wt%.

[0023] In some embodiments of the present application, the specific surface area of the coal-based activated carbon is ≥600m 2 / g, for example 600m 2 / g, 800m 2 / g, 823m 2 / g, 865m 2 / g, 912m 2 / g, 1000m 2 / g, etc., and the particle size D50 is 10-20μm, for example 10μm, 12μm, 15μm, 18μm, 20μm, etc.

[0024] In some embodiments of the present application, the mass ratio of the coal-based activated carbon to the sulfur source is 1:(1-3); for example 1:1, 1:1.5, 1:1.8, 1:2, 1:3, etc.

[0025] In some embodiments of the present application, the mixing is grinding mixing, and the particle size of the mixed powder is 200-300 mesh, for example 200 mesh, 260 mesh, 280 mesh, 300 mesh, etc.

[0026] In some embodiments of the present application, the coal-based activated carbon and potassium thiosulfate K2S2O3 are weighed in a mass ratio of 1:1-1:3, placed in an agate mortar, ground clockwise for 10 min, ground counterclockwise for 10 min, and sieved through a 200-mesh sieve to obtain a mixed powder.

[0027] In some embodiments of the present application, in step (2), the temperature of the calcination is 500-700℃, for example, 500℃, 530℃, 550℃, 580℃, 600℃, 700℃, etc., and the time of the calcination is 100-140 min, for example, 100 min, 110 min, 120 min, 130 min, 140 min, etc.

[0028] In some embodiments of the present application, the atmosphere of the calcination is an inert atmosphere, and the heating rate of the calcination is 3-8℃ / min, for example, 3℃ / min, 5℃ / min, 8℃ / min, etc. The inert atmosphere can be a nitrogen atmosphere, with a nitrogen purity of ≥99.999% and an oxygen content of ≤1 ppm, and the air is removed by pre-blowing at 200 mL / min for 30 min before heating.

[0029] In some embodiments of the present application, the mixed powder is laid flat in a quartz boat with a flatness of ≤3 mm, placed in a constant temperature zone of a tube furnace, heated to 500-600℃ at a flow rate of 100 mL / min of high-purity nitrogen, activated and doped at constant temperature for 1 h, and then naturally cooled to room temperature to obtain a black primary product. The quartz boat is pre-cleaned with anhydrous ethanol by ultrasonic cleaning for 15 min and dried at 80℃ before use to avoid the introduction of impurities; after calcination, the tube furnace is naturally cooled to ≤40℃ in a nitrogen atmosphere before the sample is removed to prevent high-temperature oxidation.

[0030] In some embodiments of the present application, in step (3), water washing is performed until the conductivity of the filtrate is ≤5 μS / cm, and then ethanol washing is performed. When water washing is performed, the primary product is transferred to a beaker, deionized water is added to the beaker, stirred at a magnetic stirring speed of 300 rpm for 30 min at 25℃, then filtered, and the filter cake is washed with deionized water; the filter cake is then dispersed in deionized water again, filtered, and the filter cake is washed with deionized water, and the operation of dispersing the filter cake in water, filtering, and washing is repeated until the conductivity of the filtrate is ≤5 μS / cm.

[0031] The filtration method in the embodiments of the present application uses a Buchner funnel-sand core filter bottle combination, the sand core has a pore size of 10-15 μm, and the inner wall of the funnel is pre-coated with 1 wt% polytetrafluoroethylene emulsion to reduce sample adhesion.

[0032] In some embodiments of the present application, the filter cake is dispersed in ethanol, ultrasonic treatment is performed at 25℃ for 5 min, then suction filtration is performed, and the filter cake is washed with anhydrous ethanol. The washed filter cake is placed in a vacuum drying oven and dried at 80℃, -0.09 MPa for 12 h; ground and sieved to obtain the sulfur-doped coal-based activated carbon. After ethanol leaching, the filter cake is transferred in a wet state using anhydrous ethanol before vacuum drying to avoid loss caused by peeling of the suction filtration membrane. The dried powder is cooled to room temperature in a nitrogen-filled glove box and then sealed for storage to prevent oxidation of the sulfur functional groups.

[0033] In some embodiments of the present application, the method further comprises the step of preparing the coal-based activated carbon. The specific operation steps include: contacting the bituminous coal powder with water vapor for activation treatment to obtain the coal-based activated carbon.

[0034] In some embodiments of the present application, water vapor is introduced into the bituminous coal powder, and the activation treatment is performed at a temperature of 700-900℃, for example, 700℃, 730℃, 800℃, 850℃, 900℃, etc., for 100-150 min; more preferably, the flow rate of the introduced water vapor is 0.4-0.6 mL / min. The bituminous coal is crushed to 100 mesh, heated to 800℃ at a rate of 10℃ / min under a nitrogen atmosphere, water vapor is introduced (flow rate 0.5 mL / min) for activation for 2 h, and after cooling, acid washing and water washing to neutral, the coal-based activated carbon with a specific surface area ≥600 m 2 / g and a particle size D50 of about 15 μm is obtained after drying.

[0035] The embodiments of the present application also provide a sulfur-doped coal-based activated carbon prepared by the preparation method of the first aspect of the present application. The sulfur-doped coal-based activated carbon has good desalination performance.

[0036] The embodiments of the present application also provide an electrode comprising the sulfur-doped coal-based activated carbon of the second aspect of the present application. The sulfur-doped coal-based activated carbon, conductive carbon black and polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 8:1:1, then N-methyl pyrrolidone is added, and stirring is performed at 25℃, 500 rpm for 4 h to obtain a slurry; the slurry is coated on a carbon paper current collector using a doctor blade coater, the wet film thickness is 200 μm, then vacuum drying is performed at 80℃ for 12 h, rolling is performed to form a film, and the film is cut into 40 mm×40 mm electrode pieces, and the active material loading is about 5-8 mg / cm 2 During the preparation process, the carbon paper current collector is pre-wiped with anhydrous ethanol and dried at 80℃ to remove surface oil stains; the film coating process is completed in a drying room to avoid slurry moisture absorption and agglomeration. After rolling, the electrode pieces are dried again in a vacuum drying oven at 80℃, -0.09 MPa for 4 h to remove residual solvents.

[0037] The application further provides a capacitive deionization device comprising the electrode of the third aspect of the application. Before the capacitive deionization device is used for desalination, the electrode is cyclic voltammetry activated in 1M sodium chloride solution for 10 cycles to stabilize the surface functional groups thereof.

[0038] In some embodiments of the application, the capacitive deionization device comprises a device for removing chloride ions or sodium ions.

[0039] The technical solutions of the application are further described below with reference to specific embodiments.

[0040] Embodiment 1 A preparation method of sulfur-doped coal-based activated carbon comprises the following steps: (1) Water vapor is introduced into pulverized bituminous coal with a particle size of 200-300 mesh, and the temperature is raised to 800°C, and the flow rate of the introduced water vapor is controlled to be 0.5 mL / min, and the activated treatment is performed for 120 min; after the activation is completed, the temperature is cooled to room temperature, then the coal-based activated carbon is sequentially immersed in 1M HCl solution for 12 h, and then washed with deionized water until neutral, and dried at 80°C for 12 h to obtain coal-based activated carbon with a specific surface area of 677.66 m 2 / g and a particle size D50 of about 15 μm.

[0041] (2) The coal-based activated carbon and potassium thiosulfate are mixed in a mass ratio of 1:2, ground in a agate mortar, and sieved to obtain a mixed powder with a particle size of 200-300 mesh; (3) The mixed powder is laid flat in a quartz boat with a thickness of 3 mm, placed in the constant temperature zone of a tube furnace, and heated to 600°C at a heating rate of 5°C / min under the protection of high-purity nitrogen gas with a flow rate of 100 mL / min, and then activated and doped for 2 h, and then naturally cooled to room temperature to obtain a black primary product; (4) The black primary product is dispersed in 50 ml of deionized water, magnetically stirred at 25°C and 300 rpm for 30 min to form a dispersion, the dispersion is filtered and the filter cake is rinsed with deionized water; the filter cake is then dispersed in deionized water, filtered, and rinsed with deionized water until the conductivity of the filtrate is ≤5 μS / cm (3.8 μS / cm); then the filter cake is dispersed in ethanol, ultrasonically treated at 25°C for 5 min, filtered, and dried in a vacuum drying oven at a vacuum degree of -0.09 MPa and a temperature of 80°C for 12 h to obtain the sulfur-doped coal-based activated carbon.

[0042] Embodiment 2 The preparation method of the sulfur-doped coal-based activated carbon of embodiment 2 is different from that of embodiment 1 only in that the ratio of the amount of the coal-based activated carbon to the amount of the sulfur source in the preparation process of the sulfur-doped coal-based activated carbon of embodiment 2 is different from that of embodiment 1.

[0043] The specific operation steps include: (1) steam was introduced into the bituminous coal powder with particle size of 200-300 mesh, and heated to 800℃, the flow rate of the introduced steam was controlled at 0.5 mL / min, and the activation treatment was performed for 120 min; after the activation was completed, the temperature was cooled to room temperature, then 1M HCl solution was used for immersion for 12 h, and then deionized water was used for washing until neutral, and the mixture was dried at 80℃ for 12 h to obtain the coal-based activated carbon with specific surface area of ≥677.66 m 2 / g and particle size D50 of about 15 μm.

[0044] (2) the coal-based activated carbon and potassium thiosulfate with mass ratio of 1:1 were mixed, ground in a marver mortar, and sieved to obtain the mixed powder with particle size of 200-300 mesh; the remaining operations were the same as those in Example 1.

[0045] Example 3 The difference between the preparation method of the sulfur-doped coal-based activated carbon described in Example 3 and that in Example 1 is only that the mass ratio of the coal-based activated carbon to the sulfur source in the preparation process of the sulfur-doped coal-based activated carbon described in Example 3 is different from that in Example 1.

[0046] The specific operation steps include: (1) steam was introduced into the bituminous coal powder with particle size of 200-300 mesh, and heated to 800℃, the flow rate of the introduced steam was controlled at 0.5 mL / min, and the activation treatment was performed for 120 min; after the activation was completed, the temperature was cooled to room temperature, then 1M HCl solution was used for immersion for 12 h, and then deionized water was used for washing until neutral, and the mixture was dried at 80℃ for 12 h to obtain the coal-based activated carbon with specific surface area of ≥677.66 m 2 / g and particle size D50 of about 15 μm.

[0047] (2) the coal-based activated carbon and potassium thiosulfate with mass ratio of 1:3 were mixed, ground in a marver mortar, and sieved to obtain the mixed powder with particle size of 200-300 mesh; the remaining operations were the same as those in Example 1.

[0048] Example 4 The difference between the preparation method of the sulfur-doped coal-based activated carbon described in Example 4 and that in Example 1 is only that the mass ratio of the coal-based activated carbon to the sulfur source in the preparation process of the sulfur-doped coal-based activated carbon described in Example 4 is 1:1, and the calcination temperature is 500℃.

[0049] Example 5 The difference between the preparation method of the sulfur-doped coal-based activated carbon described in Example 5 and that in Example 1 is only that the calcination temperature in the preparation process of the sulfur-doped coal-based activated carbon described in Example 5 is 500℃.

[0050] Example 6 The difference between the preparation method of the sulfur-doped coal-based activated carbon described in Example 6 and Example 1 is that the temperature of calcination in the preparation process of the sulfur-doped coal-based activated carbon described in Example 6 is 700°C.

[0051] Performance study of the sulfur-doped coal-based activated carbon described in Examples 1-6 of the present application 1. The SEM images of the sulfur-doped coal-based activated carbon described in Examples 1-3 of the present application are shown in Figures 1-3, respectively.

[0052] As can be seen from Figures 1-3, the sulfur-doped coal-based activated carbon prepared by the preparation method described in Example 1 of the present application is successfully doped with sulfur source, and the element distribution is uniform without obvious agglomeration phenomenon.

[0053] 2. Determination of cyclic voltammetry (CV) curves of the sulfur-doped coal-based activated carbon described in Examples 1 and 4-5 of the present application The same weight of the sulfur-doped coal-based activated carbon described in Examples 1 and 4-5 of the present application was coated on a 1 cm x 1 cm graphite sheet, and the loading amount was controlled at 4 mg / cm 2 , and after vacuum drying at 60°C for 12 hours, it was used as a working electrode, a 1 cm 2 Pt sheet was used as a counter electrode, and a saturated calomel electrode (saturated KCl) was used as a reference electrode, and 50 mL of 1 mol / L NaCl was used as an electrolyte; nitrogen was passed for 15 minutes before the experiment to remove oxygen, and nitrogen overpressure was maintained during the entire test process; the initial potential was set to 0 V on the electrochemical workstation, the upper limit potential was +0.6 V, the lower limit potential was -0.2 V, the scan rate was usually selected to be 2-100 mV / s, the anodic integral charge Q = ∫|I|dt, and the specific capacitance Cs = Q / (2mΔV) was calculated, and the results are shown in Figures 4 to 6 .

[0054] As can be seen from Figures 4 to 6 : the sulfur-doped coal-based activated carbon described in Example 1 of the present application has a larger specific capacitance than the sulfur-doped coal-based activated carbon described in Examples 4-5.

[0055] 3. Desalination capacity test of the electrode prepared from the sulfur-doped coal-based activated carbon described in Examples 1, 4-5 of the present application under different voltages Research method: the sulfur-doped coal-based activated carbon described in Examples 1 and 4-5 was mixed with conductive carbon black and PVDF according to a mass ratio of 8:1:1 to prepare slurry, a doctor blade coater was used to coat the above-mentioned slurry on a carbon paper current collector, the wet film thickness was 200 μm, then vacuum drying was carried out at 80°C for 12 h, film was prepared by rolling, and a 40 mm x 40 mm electrode sheet was cut.

[0056] In the capacitive deionization (CDI) experiment, the desalination rate was measured by washing the activated carbon electrodes described in Examples 1 and 4-5, vacuum drying at 60°C to constant weight, accurately weighing the active material mass to obtain a reliable electrode mass reference; then 40 mL of NaCl solution with the target concentration was prepared with deionized water, and its initial conductivity was measured with a conductivity meter and recorded; the electrodes were all assembled in the "positive electrode-separator-negative electrode" order into a acrylic cavity, with a fixed effective area of 16 cm 2 , the gaskets were tightly pressed around, the inlet and outlet were connected to a peristaltic pump to form a closed loop, and the conductivity reading was stabilized by circulating at 12 mL / min for 10 minutes without voltage, and the reading was recorded as the true initial concentration Co; then a constant direct current voltage of 0.6-1.2V was immediately applied, and the conductivity σ(t) was automatically recorded every 5 seconds for 30 minutes; after the time, the power was turned off quickly, the solution was completely discharged and weighed to obtain V1, the final concentration Ce was immediately measured, and the salt adsorption capacity SAC=(Co-Ce)V / m per unit mass was calculated; after adsorption, the two electrodes were short-circuited or a reverse voltage was applied, the flow rate was kept constant, and the conductivity was raised to close to Co, i.e. the next cycle was entered, and the test results are shown in Figure 7 .

[0057] As can be seen from Figure 7 , compared with the electrodes prepared from the sulfur-doped coal-based activated carbon described in Examples 4-5, the electrodes prepared from the sulfur-doped coal-based activated carbon described in Example 1 have a larger desalination capacity.

[0058] The desalination capacity of the electrodes prepared from the sulfur-doped coal-based activated carbon described in Examples 1, 3 and 6 at different voltages was tested, as shown in Figure 8 . (Test method refers to the test of Examples 1, 4-5) As can be seen from Figure 8 , compared with the electrodes prepared from the sulfur-doped coal-based activated carbon described in Examples 3 and 6, the electrodes prepared from the sulfur-doped coal-based activated carbon described in Example 1 have a larger desalination capacity.

[0059] Although the above examples have been shown and described, it is understood that the above examples are exemplary and cannot be construed as limiting the present application, and changes, modifications, replacements and variations of the above examples made by those of ordinary skill in the art are within the scope of the present application.

Claims

1. A method for preparing sulfur-doped coal-based activated carbon, characterized in that, Includes the following steps: (1) Mix coal-based activated carbon and sulfur source to obtain mixed powder; (2) The mixed powder is calcined to obtain the initial product; (3) The initial product was washed with water and ethanol in sequence to obtain the sulfur-doped coal-based activated carbon.

2. The method for preparing sulfur-doped coal-based activated carbon according to claim 1, characterized in that, In step (1), the sulfur source is potassium thiosulfate; the specific surface area of ​​the coal-based activated carbon is ≥600 m². 2 / g, with a particle size D50 of 10-20μm.

3. The method for preparing sulfur-doped coal-based activated carbon according to claim 1, characterized in that, The mass ratio of the coal-based activated carbon to the sulfur source is 1:(1-3); the mixing is performed by grinding, and the particle size of the mixed powder is 200-300 mesh.

4. The method for preparing sulfur-doped coal-based activated carbon according to claim 1, characterized in that, In step (2), the calcination temperature is 500-700℃, the calcination time is 100-140min, the calcination atmosphere is nitrogen atmosphere, and the calcination heating rate is 3-8℃ / min.

5. The method for preparing sulfur-doped coal-based activated carbon according to claim 1, characterized in that, In step (3), the filtrate is washed with water until the conductivity of the filtrate is ≤5μS / cm, and then washed with ethanol.

6. The method for preparing sulfur-doped coal-based activated carbon according to claim 1, characterized in that, It also includes the steps of preparing coal-based activated carbon; The specific operating steps include: contacting bituminous coal powder with water vapor to activate it, thereby obtaining coal-based activated carbon; Preferably, steam is introduced into the bituminous coal powder and activated at a temperature of 700-900℃ for 100-150 min; more preferably, the steam flow rate is 0.4-0.6 mL / min.

7. A sulfur-doped coal-based activated carbon, characterized in that, It is prepared by the preparation method described in any one of claims 1-6.

8. An electrode, characterized in that, Includes the sulfur-doped coal-based activated carbon as described in claim 7.

9. A capacitor deionization device, characterized in that, Includes the electrode as described in claim 8.

10. The capacitor deionization device according to claim 9, characterized in that, The capacitor deionization device includes a device for removing chloride or sodium ions.

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