CN105990031A - Diaminobenzene functionalized graphene-doped active carbon composite electrode, preparation method thereof and application of diaminobenzene-functionalized graphene-doped active carbon composite electrode to electric adsorption desalination - Google Patents

Abstract

The invention discloses an activated carbon composite electrode doped with diaminobenzene functionalized graphene, its preparation and its application in electro-adsorption desalination. The preparation method includes the following two steps: (1) preparation of diaminobenzene-functionalized graphene; (2) uniformly mixing activated carbon with diaminobenzene-functionalized graphene and a binder, and preparing different proportions of graphene after molding in a mold. Surface area and adsorption capacity of composite electrodes. Using the composite electrode as the positive and negative electrodes of the electro-adsorption device can be used in fields such as desalination of secondary biochemical effluent, and its desalination efficiency is significantly better than that of a simple carbon electrode.

Description

Diaminobenzene functionalized graphene-doped activated carbon composite electrode, its preparation and its application in electrosorption desalination

technical field

The invention relates to an activated carbon composite electrode doped with diaminobenzene functionalized graphene, its preparation and its application in electroadsorption desalination, belonging to the field of capacitive deionization.

Background technique

At present, the shortage of water resources has become a serious problem in the world, and desalination of seawater can alleviate the current situation of water shortage. Compared with traditional technologies such as reverse osmosis, electrodialysis and rotary evaporation, capacitive deionization (CDI, also known as electric Adsorption) has become a potential desalination method. The process of desalination uses charge attraction to adsorb ions on the electrode surface. When an external power source is connected, oppositely charged ions are attracted to the electrode surface, forming an electric double layer. When the power is removed, the ions resolve and return to the solution without secondary pollution. Based on the principle of electric double layer, the adsorption capacity of CDI is closely related to the conductivity and surface properties of the electrode.

In recent years, activated carbons with different specific surface areas and pore structures have been widely reported, including activated carbons, carbon aerogels, carbon nanotubes, and some composite activated carbons. Although activated carbon is widely used, it is not conducive to the adsorption and desorption of ions because it is mostly microporous (<2nm). To solve this problem, scientists have developed graphene with a sheet structure as an electrode material. Graphene has a two-dimensional structure and has the advantages of large specific surface area, good electrical conductivity, good mechanical properties and chemical stability. The special results and electrical properties make graphene and its composites excellent materials for energy storage and adsorption. In recent years, some research groups have carried out work on graphene adsorption desalination, such as: Li Haibo (Environ.Sci.Technol., 2010,44,8692-8697) of East China University of Science and Technology, Zhang et al. (J.Mater .Chem., 2012, 22, 14696-14704) By comparing the properties of graphene electrodes with different proportions, optimizing material properties, and developing graphene electrodes with electroadsorption and desalination properties. Due to the relatively low electric adsorption capacity of pure graphene, its advantages cannot be fully exerted. More work has focused on the development of composite materials, but few reports have reported the functionalization of graphene as an adsorption electrode.

Contents of the invention

The purpose of the present invention is to provide a composite electro-adsorption electrode with high removal rate and its preparation method, which has high adsorption capacity and desorption efficiency.

Another object of the present invention is to provide the application of the above-mentioned composite electrosorption electrode.

The technical solution for realizing the present invention is: a kind of activated carbon composite electrode doped with diaminobenzene functionalized graphene, using diaminobenzene functionalized graphene as conductive additive, utilizing binder to diaminobenzene functionalized graphene and Activated carbon is uniformly blended to construct a composite material, and the composite material is fixed on the electrode sheet through film molding, and the composite electrode is obtained after vacuum drying.

In the composite electrode above, the binder is one or a mixture of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene glycol, and the like.

In the above composite electrode, the electrode sheet is made of aluminum, nickel, titanium, copper or stainless steel, and its form is one of mesh, foil and sponge.

In the composite electrode above, the diaminobenzene functionalized graphene structure is as follows:

In the above composite electrode, in terms of mass ratio, activated carbon:diaminobenzene functionalized graphene:binder=(99:1:50)˜(19:1:20).

The preparation method of the activated carbon composite electrode doped with diaminobenzene functionalized graphene, its steps are as follows:

(a) Under ultrasound, prepare a DMF suspension of graphene oxide, mix the suspension with a DMF solution of diaminobenzene (PA), heat to 70-100°C and stir to react, filter under reduced pressure, wash and dry to obtain Diaminobenzene functionalized graphene, wherein the ratio of graphite oxide to DMF solvent is 7.5-15mg/mL, and the mass ratio of graphene oxide to diaminobenzene is 1:10-10:1;

(b) After the diaminobenzene functionalized graphene is ground, it is blended with activated carbon to prepare a composite of diaminobenzene functionalized graphene and activated carbon in different proportions, and it is dissolved in an organic solvent and mixed uniformly, wherein , the mass ratio of activated carbon to diaminobenzene functionalized graphene is (99:1)～(19:1);

(c) dissolving the binder in an organic solvent and mixing evenly, wherein the mass ratio of the diaminobenzene functionalized graphene to the binder is (1:50) to (1:20);

(d) mix (b) and (c) evenly, and ultrasonicate for 6-8 hours after grinding;

(e) Coating the prepared composite material evenly on the electrode, press molding, and vacuum drying at 60-80° C. for 16-24 hours to obtain the activated carbon composite electrode.

In step (a), the ultrasonic time is 2 to 10 hours; diaminobenzene is any one of p-phenylenediamine, m-phenylenediamine and o-phenylenediamine; the ratio of diaminobenzene to DMF solvent is 1:10～ 1:500g/mL; the temperature range of the DMF solution of diaminobenzene is 25-80°C; the stirring reaction time is 5-24h.

In step (b), the mass ratio of diaminobenzene functionalized graphene and activated carbon total mass to organic solvent is

(1:1～2:1), the organic solvent is methanol or ethanol.

In step (c), the mass ratio of the binder to the organic solvent is (10:8˜2:6), and the organic solvent is methanol or ethanol.

The application of the above diaminobenzene functionalized graphene-doped binary activated carbon composite electrode in electrosorption desalination.

The removed ions include Na ⁺ , Mg ²⁺ , Ca ²⁺ , F ^- , NO ₃ ^- , NO ₂ ^- , HCO ₃ ^- , SO ₄ ^2- and PO ₄ ^3- , etc. The adsorption time is 20-150 minutes. The desorption time is 20-150 minutes, and the energizing voltage is 1.0-2.0V.

Compared with prior art, the advantage of the present invention is:

The invention utilizes the characteristics of strong conductivity and large specific surface area of the diaminobenzene functionalized graphene to prepare an activated carbon composite electrode doped with the diaminobenzene functionalized graphene. The electrode prepared by the method has the following characteristics: 1. large specific surface area; 2. good electrical conductivity; 3. high adsorption capacity; 4. high adsorption efficiency; 5. good desorption performance.

These characteristics make the composite material widely used in urban sewage and municipal wastewater treatment and other fields.

Description of drawings

Fig. 1 is the SEM image of diaminobenzene functionalized graphene in Example 1 of the present invention.

Fig. 2 is the infrared spectrogram of the functionalized graphene nanomaterial synthesized in Example 1 of the present invention.

Fig. 3 is the infrared spectrogram of the functionalized graphene nanomaterial synthesized in Example 2 of the present invention.

Fig. 4 is the AC impedance result of the composite electrode in Example 6 of the present invention.

Fig. 5 is a comparison of the adsorption of NaCl between the composite electrode of Example 7 of the present invention and the simple activated carbon electrode.

detailed description

Embodiment 1-3: the preparation of diaminobenzene functionalized graphene:

Example 1

The first step, the preparation of graphite oxide solid;

At 80°C, 20g of natural graphite was pre-oxidized with 30mL of concentrated sulfuric acid, 10g of potassium persulfate and 10g of phosphorus pentoxide, washed with water until pH = 7, and dried at room temperature overnight for use;

Cool 460mL of concentrated sulfuric acid to about 0°C, then add 20g of pre-oxidized graphite into it, slowly add 60g of potassium permanganate so that the temperature of the system does not exceed 20°C, after the addition is completed, raise the temperature to 35°C, and stir for 2 hours, And slowly add 920mL of deionized water in batches, so that the system temperature does not exceed 98°C, and after stirring for 15 minutes, add 2.8L of deionized water and 50mL of 30% hydrogen peroxide. The resulting bright yellow suspension was filtered under reduced pressure and washed. Until there is no sulfate ion in the filtrate, and when it is neutral, the product is dried in vacuum at 60°C to obtain graphite oxide solid;

In the second step, 50 mg of graphite oxide powder is put into a round bottom flask, and then 15 mL of N,N-dimethylformamide (DMF) solvent is added, and after ultrasonication for 5 hours, a suspension of graphene oxide (GO) is obtained;

In the third step, 0.1 g of p-phenylenediamine was dissolved in 5 mL of DMF at room temperature to prepare a DMF solution of p-phenylenediamine;

In the fourth step, the p-phenylenediamine solution in the third step is slowly added dropwise to the GO suspension prepared in the second step, heated to 85°C, and vigorously stirred for 8h;

In the fifth step, the crude product obtained in the fourth step is suction-filtered, washed and dried to obtain the product.

The infrared spectrum of the functionalized graphene nanomaterial in solvent is shown in Fig. 2, which proves that the nano-hybrid material has been successfully synthesized. The photo of the functionalized graphene nanomaterial is shown in the SEM of Figure 1.

Example 2

The first to second steps are the same as steps one to two in Example 1.

In the third step, 0.1 g of m-phenylenediamine was dissolved in 5 mL of DMF at room temperature to prepare a DMF solution of m-phenylenediamine;

In the fourth step, the m-phenylenediamine solution in the third step is slowly added dropwise to the GO suspension prepared in the second step, heated to 85°C, and vigorously stirred for 8h;

The fifth step is the same as step five in Example 1.

The infrared spectrum of the functionalized graphene nanomaterial in solvent is shown in Fig. 3, which proves that the nano-hybrid material has been successfully synthesized.

Example 3

The first to second steps are the same as steps one to two in Example 1.

In the third step, 0.1 g of o-phenylenediamine was dissolved in 5 mL of DMF at room temperature to prepare a DMF solution of o-phenylenediamine;

In the fourth step, the o-phenylenediamine solution in the third step is slowly added dropwise to the GO suspension prepared in the second step, heated to 100°C, and vigorously stirred for 24 hours;

The fifth step is the same as step five in Example 1.

Example 4-12: Preparation and Application of Composite Electrode

Example 4

Preparation of composite electrode: (1) take the quality of diaminobenzene functionalized graphene and activated carbon powder in Example 1 respectively to be 1g and 19g, and mix them uniformly according to the ratio of 1:19; (2) mix the two The material was mixed and ground in a mortar for 30 minutes; (3) the homogeneously mixed material was dissolved in 300mL of methanol, and continued to stir until uniformly mixed; (4) ultrasonic for 5 hours; (5) weigh the binder PTFE according to the ratio 1: 2 (the mass of PTFE is 66g) is dissolved in 200mL methanol, put it into the beaker and disperse for 1 hour; (6) Stir with a glass rod to mix the two evenly, and continue ultrasonication for 3 hours; (6) Mix evenly Spread the material evenly on the electrode sheet, and use a machine to form a film; (7) Air-dry the electrode for 24 hours; (8) Dry it in vacuum at 80°C for 24 hours, and set it aside.

Electrosorption studies on composite electrodes: The freshly prepared composite electrodes were taken out of the oven, cooled, and soaked in ultrapure water for 24 hours. Then assemble the electrosorption device and conduct the desalination experiment. The specific steps are as follows: (1) The prepared composite electrode sheet is installed in the self-made electrosorption device as the positive and negative electrodes; (2) Connected to a DC power supply, and the electrification voltage of the two poles is 1.6V; (3) Prepare 240mg/L NaCl solution , take 1000mL solution for desalination experiment; (4) The adsorption time is 40 minutes; (5) The electrode is short-circuited for desorption, and the time is 60 minutes; (6) The desalination rate under the above conditions can reach 80%.

Example 5

The preparation of composite electrode: (1) take the mass of diaminobenzene functionalized graphene and activated carbon powder in Example 2 to be 0.2g and 19.8g respectively, mix according to the ratio of 1:99; (2) Mix the two substances in a mortar and grind for 30 minutes; (3) Dissolve the uniformly mixed material in 300mL methanol, continue to stir, and mix evenly; (4) Ultrasound for 5 hours; (5) Weigh the binder PTFE according to the proportion Dissolve 1:1 (the mass of PTFE is 33g) in 200mL methanol, put it into a beaker and disperse for 1 hour; (6) Stir with a glass rod to mix the two evenly, and continue to ultrasonic for 3 hours; (6) Mix evenly The finished material is spread evenly on the electrode sheet, and is pressed into a film by a machine; (7) The electrode is air-dried for 24 hours; (8) Dry it in a vacuum at 80°C for 24 hours, and set aside.

Electrosorption studies on composite electrodes: The freshly prepared composite electrodes were taken out of the oven, cooled, and soaked in ultrapure water for 24 hours. Then assemble the electrosorption device and conduct the desalination experiment. The specific steps are as follows: (1) The prepared composite electrode sheet is installed in the self-made electrosorption device as the positive and negative electrodes; (2) Connected to a DC power supply, and the electrification voltage of the two poles is 1.6V; (3) Prepare 240mg/L NaCl solution , take 1000mL solution for desalination experiment; (4) The adsorption time is 40 minutes; (5) The desorption time is 60 minutes when the electrode is short-circuited; (6) The desalination rate can reach 85% under the above conditions.

Example 6

The preparation of composite electrode: (1) take the mass of diaminobenzene functionalized graphene and activated carbon powder in Example 2 to be 2g and 18g respectively, mix according to the ratio of 1:9; (2) mix the two kinds The material was mixed and ground in a mortar for 30 minutes; (3) the homogeneously mixed material was dissolved in 300mL ethanol, continued to stir, and mixed uniformly; (4) ultrasonicated for 5 hours; (5) the binder PTFE was weighed according to the ratio 1: 1 (the mass of PTFE is 33g) dissolved in 200mL ethanol, put it into a beaker and disperse for 1 hour; (6) Stir with a glass rod to mix the two evenly, and continue ultrasonication for 3 hours; (6) Mix evenly Spread the material evenly on the electrode sheet, and use a machine to form a film; (7) Air-dry the electrode for 24 hours; (8) Dry it in vacuum at 80°C for 24 hours, and set it aside.

Electrosorption studies on composite electrodes: The freshly prepared composite electrodes were taken out of the oven, cooled, and soaked in ultrapure water for 24 hours. Then assemble the electrosorption device and conduct the desalination experiment. The specific steps are as follows: (1) The prepared composite electrode sheet is installed in a self-made electrosorption device as the positive and negative electrodes; (2) Connected to a DC power supply, and the voltage of the two poles is 1.8V; (3) Prepare 240mg/L NaCl solution , take 1000mL solution for desalination experiment; (4) adsorption time is 40 minutes; (5) electrode short circuit desorption time is 60 minutes; (6) desalination rate can reach 88% under the above conditions. Figure 4 shows the AC impedance results of the electrodes. It can be seen from the results that the electrode has a small resistance and is suitable for use as an electrode for electroadsorption desalination.

Example 7

Preparation of composite electrode: (1) take the quality of diaminobenzene functionalized graphene and activated carbon powder in Example 2 to be 1g and 19g respectively, and mix them uniformly according to the ratio of 1:19; (2) mix the two The material was mixed and ground in a mortar for 30 minutes; (3) the homogeneously mixed material was dissolved in 300mL ethanol, continued to stir, and mixed uniformly; (4) ultrasonicated for 5 hours; (5) the binder PTFE was weighed according to the ratio 1: 1 (the mass of PTFE is 33g) dissolved in 200mL ethanol, put it into a beaker and disperse for 1 hour; (6) Stir with a glass rod to mix the two evenly, and continue ultrasonication for 3 hours; (6) Mix evenly Spread the material evenly on the electrode sheet, and use a machine to form a film; (7) Air-dry the electrode for 24 hours; (8) Dry it in vacuum at 80°C for 24 hours, and set it aside.

Electrosorption studies on composite electrodes: The freshly prepared composite electrodes were taken out of the oven, cooled, and soaked in ultrapure water for 24 hours. Then assemble the electrosorption device and conduct the desalination experiment. The specific steps are as follows: (1) The prepared composite electrode sheet is installed in a self-made electrosorption device as the positive and negative electrodes; (2) Connected to a DC power supply, and the voltage of the two poles is 1.8V; (3) Prepare 240mg/L NaCl solution , take 1000mL solution for desalination experiment; (4) The adsorption time is 40 minutes; (5) The electrode is short-circuited for desorption, and the time is 60 minutes; (6) The desalination rate under the above conditions can reach 90%. Figure 5 is a comparison of the adsorption of NaCl by the composite electrode (AC/GEA2) and the simple activated carbon electrode (AC). The results show that the desalination effect of the composite electrode is significantly better than that of the pure activated carbon electrode.

Example 8

The preparation of composite electrode: (1) take the mass of diaminobenzene functionalized graphene and activated carbon powder in Example 2 to be 0.2g and 19.8g respectively, mix according to the ratio of 1:99; (2) Mix the two substances in a mortar and grind for 30 minutes; (3) Dissolve the uniformly mixed material in 300mL methanol, continue to stir, and mix evenly; (4) Ultrasound for 5 hours; (5) Weigh the binder PTFE according to the proportion 1:2 (the mass of PTFE is 66g) was dissolved in 200mL methanol, put it in a beaker and dispersed for 1 hour; (6) Stir with a glass rod to mix the two evenly, and continue to ultrasonic for 3 hours; (6) Mix evenly The finished material is spread evenly on the electrode sheet, and is pressed into a film by a machine; (7) The electrode is air-dried for 24 hours; (8) Dry it in a vacuum at 80°C for 24 hours, and set aside.

Electrosorption studies on composite electrodes: The freshly prepared composite electrodes were taken out of the oven, cooled, and soaked in ultrapure water for 24 hours. Then assemble the electrosorption device and conduct the desalination experiment. The specific steps are as follows: (1) The prepared composite electrode sheet is installed in a self-made electrosorption device as the positive and negative electrodes; (2) Connected to a DC power supply, and the voltage of the two poles is 1.8V; (3) Prepare 240mg/L NaCl solution , take 1000mL solution for desalination experiment; (4) adsorption time is 40 minutes; (5) electrode short circuit desorption time is 60 minutes; (6) desalination rate can reach 87% under the above conditions.

Example 9

Preparation of composite electrode: (1) take the quality of diaminobenzene functionalized graphene and activated carbon powder in Example 3 to be 1g and 19g respectively, and mix them uniformly according to the ratio of 1:19; (2) mix the two The material was mixed and ground in a mortar for 30 minutes; (3) the homogeneously mixed material was dissolved in 300mL of methanol, and continued to stir until uniformly mixed; (4) ultrasonic for 5 hours; (5) weigh the binder PTFE according to the ratio 1: 2 (the mass of PTFE is 66g) is dissolved in 200mL methanol, put it into the beaker and disperse for 1 hour; (6) Stir with a glass rod to mix the two evenly, and continue ultrasonication for 3 hours; (6) Mix evenly Spread the material evenly on the electrode sheet, and use a machine to form a film; (7) Air-dry the electrode for 24 hours; (8) Dry it in vacuum at 80°C for 24 hours, and set it aside.

Electrosorption studies on composite electrodes: The freshly prepared composite electrodes were taken out of the oven, cooled, and soaked in ultrapure water for 24 hours. Then assemble the electrosorption device and conduct the desalination experiment. The specific steps are as follows: (1) The prepared composite electrode sheet is installed in the self-made electrosorption device as the positive and negative electrodes; (2) Connected to a DC power supply, and the electrification voltage of the two poles is 1.6V; (3) Prepare 240mg/L NaCl solution , take 1000mL solution for desalination experiment; (4) The adsorption time is 40 minutes; (5) The electrode is short-circuited for desorption, and the time is 60 minutes; (6) The desalination rate under the above conditions can reach 80%.

Example 10

Preparation of composite electrode: (1) take the quality of diaminobenzene functionalized graphene and activated carbon powder in Example 1 respectively to be 1g and 19g, and mix them uniformly according to the ratio of 1:19; (2) mix the two The material was mixed and ground in a mortar for 30 minutes; (3) the homogeneously mixed material was dissolved in 300mL of methanol, and continued to stir until uniformly mixed; (4) ultrasonic for 5 hours; (5) weigh the binder PTFE according to the ratio 1: 1 (the mass of PTFE is 33g) dissolved in 200mL of methanol, put it into a beaker and disperse for 1 hour; (6) Stir with a glass rod to mix the two evenly, then continue ultrasonication for 3 hours; (6) Mix evenly Spread the material evenly on the electrode sheet, and use a machine to form a film; (7) Air-dry the electrode for 24 hours; (8) Dry it in vacuum at 80°C for 24 hours, and set it aside.

Electrosorption studies on composite electrodes: The freshly prepared composite electrodes were taken out of the oven, cooled, and soaked in ultrapure water for 24 hours. Then assemble the electrosorption device and conduct the desalination experiment. The specific steps are as follows: (1) The prepared composite electrode sheet is installed in a self-made electrosorption device as the positive and negative electrodes; (2) Connected to a DC power supply, and the voltage of the two poles is 1.8V; (3) Prepare 240mg/L NaCl solution , take 1000mL solution for desalination experiment; (4) The adsorption time is 40 minutes; (5) The desorption time is 60 minutes when the electrode is short-circuited; (6) The desalination rate can reach 85% under the above conditions.

Example 11

The preparation of electrode: (1) take the mass of diaminobenzene functionalized graphene and activated carbon powder in embodiment 1 respectively to be 0.4g and 19.6g, mix according to the ratio of 1:99; (2) mix two The materials were mixed and ground in a mortar for 30 minutes; (3) the homogeneously mixed material was dissolved in 300mL methanol, and continued to stir until uniformly mixed; (4) ultrasonicated for 5 hours; (5) the binder PTFE was weighed according to the ratio of 1 : 2 (the quality of PTFE is 66g) is dissolved in 200mL methanol, it is put into the beaker and disperses for 1 hour; (6) After stirring with a glass rod to make the two mix evenly, continue ultrasonication for 3 hours; (6) After mixing evenly Spread the material evenly on the electrode sheet, and press it into a film with a machine; (7) air-dry the electrode for 24 hours; (8) dry it in vacuum at 80°C for 24 hours, and set it aside.

Electrosorption studies on composite electrodes: The freshly prepared composite electrodes were taken out of the oven, cooled, and soaked in ultrapure water for 24 hours. Then assemble the electrosorption device and conduct the desalination experiment. The specific steps are as follows: (1) The prepared composite electrode sheet is installed in the self-made electrosorption device as the positive and negative electrodes; (2) Connected to a DC power supply, and the electrification voltage of the two poles is 1.6V; (3) Prepare 240mg/L NaCl solution , take 1000mL solution for desalination experiment; (4) The adsorption time is 40 minutes; (5) The electrode is short-circuited for desorption, and the time is 60 minutes; (6) The desalination rate under the above conditions can reach 80%.

Claims (10)

1. An active carbon composite electrode doped with diaminobenzene functionalized graphene, characterized in that, using diaminobenzene functionalized graphene as a conductive additive, utilizing a binder to uniformly co-exist the diaminobenzene functionalized graphene and activated carbon The composite material is mixed and formed, and the composite material is fixed on the electrode sheet through film molding, and the composite electrode is obtained after vacuum drying. 2. the activated carbon composite electrode doped with diaminobenzene functionalized graphene as claimed in claim 1, is characterized in that, binding agent is a kind of in polytetrafluoroethylene, polyvinylidene fluoride and polyethylene glycol or a mixture of several. 3. the activated carbon composite electrode of diaminobenzene functionalized graphene doping as claimed in claim 1, is characterized in that, electrode plate material is aluminium, nickel, titanium, copper or stainless steel material, and its shape is net, foil film and A type of sponge. 4. the active carbon composite electrode doped with diaminobenzene functionalized graphene as claimed in claim 1, is characterized in that, diaminobenzene functionalized graphene structure is as follows: . 5. the activated carbon composite electrode doped with diaminobenzene functionalized graphene as claimed in claim 1, is characterized in that, in mass ratio, activated carbon: diaminobenzene functionalized graphene: binding agent=(99:1 :50) ~ (19:1:20). 6. a preparation method of an activated carbon composite electrode doped with diaminobenzene functionalized graphene, characterized in that, its steps are as follows: (a) Under ultrasound, prepare a DMF suspension of graphene oxide, mix the suspension with a DMF solution of diaminobenzene, heat to 70~100 °C and stir to react, filter under reduced pressure, wash, and dry to obtain diaminobenzene Functionalized graphene, the mass ratio of graphene oxide to diaminobenzene is 1:10~10:1; (b) After the diaminobenzene functionalized graphene is ground, it is blended with activated carbon to prepare composites of diaminobenzene functionalized graphene and activated carbon in different proportions, dissolved in an organic solvent, and mixed evenly, wherein activated carbon and The mass ratio of diaminobenzene functionalized graphene is (99:1)~(19:1); (c) dissolving the binder in an organic solvent and mixing evenly, wherein the mass ratio of the diaminobenzene functionalized graphene to the binder is (1:50)~(1:20); (d) Mix step (b) and step (c) evenly, and ultrasonically obtain a composite material after grinding; (e) Coating the prepared composite material evenly on the electrode, press molding, and vacuum drying at 60-80 °C, the activated carbon composite electrode can be obtained. 7. The preparation method of the activated carbon composite electrode doped with diaminobenzene functionalized graphene as claimed in claim 6, characterized in that, in step (a), the ultrasonic time is 2~10h; Any one of amine, m-phenylenediamine and o-phenylenediamine; the ratio of graphite oxide to DMF solvent in the DMF suspension of graphene oxide is 7.5~15 mg/mL; the ratio of diaminobenzene to DMF solvent is 1 :10~1:500 g/mL; the temperature range of the DMF solution of diaminobenzene is 25~80°C; the stirring reaction time is 5~24 h. 8. The preparation method of the activated carbon composite electrode doped with diaminobenzene functionalized graphene as claimed in claim 6, characterized in that, in step (b), the total mass of diaminobenzene functionalized graphene and activated carbon is equal to the organic The mass ratio of the solvent is (1:1~2:1), and the organic solvent is methanol or ethanol; in step (c), the mass ratio of the binder to the organic solvent is (10:8~2:6), and the organic solvent It is methanol or ethanol; in step (d), the ultrasonic time is 6-8 hours; in step (e), the drying time is 16-24 h. 9. The application of the diaminobenzene functionalized graphene-doped binary activated carbon composite electrode in electrosorption desalination as described in any one of claims 1-8. 10. The application according to claim 9, characterized in that the removed ions include Na ⁺ , Mg ²⁺ , Ca ²⁺ , F ^- , NO ₃ ^- , NO ₂ ^- , HCO ₃ ^- , SO ₄ ^2- and PO ₄ ^3- , the adsorption time is 20~150 minutes, the desorption time is 20~150 minutes, and the electrification voltage is 1.0~2.0 V.