CN111320160A

CN111320160A - Nitrogen-rich microporous carbon material and preparation method and application thereof

Info

Publication number: CN111320160A
Application number: CN202010124337.9A
Authority: CN
Inventors: 李丹萍; 宁寻安; 王逸; 李扬
Original assignee: Guangdong University of Technology
Current assignee: Guangdong University of Technology
Priority date: 2020-02-27
Filing date: 2020-02-27
Publication date: 2020-06-23

Abstract

The invention discloses a nitrogen-rich microporous carbon material and a preparation method and application thereof. The preparation method of the nitrogen-rich microporous carbon material comprises the following steps: refluxing hexacyclohexane octahydrate and diaminocarbonitrile in glacial acetic acid, filtering, washing with hot glacial acetic acid, and adding 30% HNO₃Heating, cooling, filtering, collecting solid, refluxing in acetonitrile, filtering, evaporating in vacuum to obtain HAT, and heating and carbonizing under the action of nitrogen flow to synthesize nitrogen-rich microporous carbon material HAT-CN-X. The HAT-CN-X of the invention has the characteristics of fast ion diffusion and strong charge transfer capacity, and the specific capacitance of the applied membrane capacitance deionization module is 179.2F g^‑1Having 24.66mg g^‑1The high-salt adsorption capacity of the composite material shows good cycle stability in 30 cycles, has large specific surface area, rich microporous structure, good conductivity, sufficient charge storage space and active sites, high MCDI performance and good regeneration performance, and is suitable for application and alkaline treatment of MCDI.

Description

Nitrogen-rich microporous carbon material and preparation method and application thereof

Technical Field

The invention relates to the technical field of capacitive deionization, and particularly relates to a nitrogen-rich microporous carbon material and a preparation method and application thereof.

Background

Water resource shortage and water safety are the two most important issues threatening and hindering the rapid and sustained development of society, both of which are exacerbated by the unavailable salt water and difficult to regenerate domestic and industrial sewage. Traditional seawater desalination technologies, such as membrane distillation, ion exchange resins, reverse osmosis, electrodialysis, and the like, have high energy consumption and high cost, and are environmentally unfriendly when regenerated using acidic or alkaline solutions and the like. Therefore, a new seawater desalination technology, Capacitive Deionization (CDI), has been rapidly developed with its excellent performance. CDI refers to the removal of ions by a capacitive adsorption method, and when a voltage is applied, a solution containing a charged substance moves to an electrode and is adsorbed, an Electric Double Layer (EDLs) is formed at an electrode-liquid interface, and then charges are desorbed back into the solution by the cancellation of an electric field or the reversal of a battery voltage. CDI can be regenerated and recovered during adsorption and desorption, and Membrane Capacitive Deionization (MCDI) integrates commercial ion exchange membranes into CDI devices, which can improve the efficiency of electro-adsorption by greatly reducing the effect of co-ions. One key parameter affecting the efficiency of CDI desalination is the performance of the electrode material, which needs to have high surface area and conductivity, good wettability and physicochemical stability. Therefore, carbon materials such as Activated Carbon (AC), Carbon Aerogel (CA), Carbon Nanotubes (CNTs), graphene, etc. are ideal candidates for CDI electrodes due to their good electrical conductivity, high Specific Surface Area (SSA), and good chemical stability. However, due to van der waals forces within graphene sheets and the mono-wettability of AC and CNTs, the effective surface area is limited, the electro-adsorption capacity does not reach the expected performance, and the high manufacturing cost and complex preparation process also limit the further applications of CDI electrodes.

In recent years, Mahmood synthesized two-dimensional crystal C in 2015₂N network, which is a novel pattern structure simulation material. C₂N has a regular hole and a larger electronic band gap (1.96eV) than g-C₃N₄With better thermodynamic stability and capacity, researchers are working on the bottom-up approach to synthesize two-dimensional crystals with tunable structure and properties. Due to C₂N has the advantages of high surface area, good crystallinity, rapid ion transmission and the like, and has wide energy and environmental application in the fields of nano electronic sensors, gas storage, batteries and the like. This is achieved byCompared with the original graphene structure, the original graphene structure is surrounded by 6N atoms, and each atom is in C₂N has a dangling bond, and the size of the hole allows anchoring of several interacting Ks⁺Or Cl^-An atom. Meanwhile, compared with the carbon material, the heteroatom doping can enhance the polarization of the structure and increase specific binding sites, and the combined action of the two can obviously improve the enthalpy of interaction between the object and the adsorbent. Relatively high nitrogen content can also improve hydrophilicity, conductivity, and capacity.

In the research of a polymeric ion membrane capacitance deionization adsorption electrode, CN 105753113 a discloses a graphene melamine foam composite membrane capacitance deionization electrode and a preparation method thereof, in the preparation method, melamine foam is used as a template to adsorb a graphene oxide aqueous solution, and then nitrogen-doped three-dimensional porous graphene material is obtained by high-temperature calcination. And coating quaternary amination polyvinyl alcohol polymer crosslinked by glutaraldehyde on the graphene melamine foam composite material as an anion exchange membrane. In a 1M sodium chloride solution as an electrolyte, the current density is 1A/g, the voltage range is-1-0V, the specific capacitance of the electrode is 176F/g, the desalting performance of the electrode is tested in 300 mu S/cm saline water, and the adsorption capacity of the electrode is 11.1 mg/g. The used raw material is graphene melamine foam, the preparation process is complex, the graphene purity is low, the used material is required to be large in specific surface area, rich in micropores and good in conductivity, the production cost in actual production is high, and the performance of the electrode material is required to be further improved.

Disclosure of Invention

The invention aims to solve the technical problems that the manufacturing cost of the existing membrane capacitor deionization electrode material is high, and the adsorption desalination performance and specific volume of the electrode material are to be further improved.

It is another object of the present invention to provide a nitrogen-rich microporous carbon material.

The invention also aims to provide application of the nitrogen-rich microporous carbon material in preparing membrane capacitance deionization electrode materials.

Another object of the present invention is to provide a membrane capacitive deionization electrode material.

Another objective of the present invention is to provide a membrane capacitive deionization module.

The present invention further provides a capacitive deionization method of the membrane capacitive deionization module.

The above purpose of the invention is realized by the following technical scheme:

a preparation method of nitrogen-rich microporous carbon material comprises the following steps:

s1, synthesizing HAT: refluxing cyclohexane octahydrate and diaminocarbonitrile in glacial acetic acid for 1-8 h, filtering a black suspension while the solution is hot, washing the black suspension with hot glacial acetic acid to obtain a black solid, and adding HNO with the mass fraction of 30% into the black solid₃Or HNO₃Heating the mixture with HCl at 50-100 ℃ for 1-5 h, pouring the dark brown suspension into water at 0 ℃ for cooling and settling, filtering and collecting solids, refluxing the solids in acetonitrile for 1-4 h, filtering, and evaporating in vacuum to obtain orange solids, namely HAT;

s2, synthesizing HAT-CN-X: uses HAT as raw material, under inert other atmosphere, carbonizing and synthesizing nitrogen-enriched microporous carbon material HAT-CN-X,

wherein the mass ratio of the hexacyclohexane octahydrate and the diaminocarbonitrile in the S1 is 1-2: 2-8;

the carbonization temperature of S2 is 450-900 ℃, the carbonization time is 1-2 h, and the heating rate is 2 ℃ for min^-1。

Wherein glacial acetic acid in S1 is used as a reaction solvent, the reaction needs to be carried out in an acidic substance, and H is provided in the reaction process⁺To ensure that polymerization occurs.

The invention adopts hot glacial acetic acid for washing, and the hot glacial acetic acid can dissolve raw materials which are not completely reacted and purify the product; the temperature of the hot glacial acetic acid for washing is equivalent to that of the reflux reaction, so that the preparation conditions are uniform.

Adding HNO₃Or HNO₃Mixtures with HCl can hydroxylate the surface of the material.

The cooling and sedimentation in the water with the temperature of 0 ℃ can utilize the water with the temperature of 0 ℃ to cool, the water entering the acid can generate a large amount of heat, and the acid is diluted, so that the reaction can be stopped.

The invention adopts an in-situ synthesis HAT condensation method to prepare a novel hexagonal carbon skeleton, has rich heteroatom and side group contents, has the potential synergistic effect of C atoms and N atoms, has the characteristics of fast ion diffusion and strong charge transfer capacity, is used as a capacitive deionization electrode, has large HAT-CN specific surface area, rich microporous structure and good conductivity, has higher MCDI performance, and provides sufficient space and active sites for charge storage. In addition, HAT-CN has high nitrogen content, good wettability and low impedance, which all contribute to the rapid transport of salt ions. Meanwhile, the HAT-CN electrode as the heteroatom carbon material has good regeneration performance, is a promising electrode material and is suitable for MCDI application and alkaline treatment.

Preferably, the mass ratio of hexacyclohexane octahydrate and diaminocarbonitrile in S1 is 1: 8.

Preferably, the carbonization temperature in S2 is 450-700 ℃, the carbonization time is 1h, and the heating rate is 2 ℃ min^-1。

Preferably, the carbonization temperature in S2 is 550 ℃, the carbonization time is 1h, and the heating rate is 2 ℃ for min^-1。

In the capacitive deionization process, the HAT-CN-X electrode can adsorb more ions in the adsorption stage than a membrane capacitive deionization module assembled by a commercial activated carbon electrode. The HAT-CN electrode was carbonized at 550 ℃ with a scan rate of 5mV s^-1Specific capacitance of 179.2F g in 1M NaCl solution^-1. Subsequently, at 500mg L^-1A voltage of 1.2V was applied to the NaCl solution to obtain 24.66mg g^-1The high salt adsorption capacity of the catalyst shows good cycle stability and excellent performance at 30 cycles.

The invention also provides the nitrogen-rich microporous carbon material prepared by the preparation method.

The application of the nitrogen-rich microporous carbon material in preparing the membrane capacitance deionization electrode material is also within the protection scope of the invention.

The electrode plate prepared from the nitrogen-rich microporous carbon material is used for membrane capacitance deionization, so that the desalting capacity, desalting efficiency and desalting rate are improved while the electrode adhesion capacity is improved, the environmental pollution is reduced, and the purpose of recycling saline-alkali water is achieved.

The invention also provides a membrane capacitance deionization electrode material, which is prepared by mixing the HAT-CN-X, acetylene black and polyvinyl alcohol, wherein the mass ratio of the HAT-CN-X, the acetylene black and the polyvinyl alcohol is 8-6: 1-2.

The working electrode of the membrane capacitive deionization module prepared from the electrode material can be specifically operated as follows:

the working electrode is prepared by mixing active ingredients (HAT-CN-X), acetylene black and polyvinyl alcohol to form uniform slurry, coating the slurry on a titanium mesh, and crosslinking in a vacuum oven for 1h at 110 ℃.

Preferably, the mass ratio of the HAT-CN-X, the acetylene black and the polyvinyl alcohol is 8:1: 1. Acetylene black is used to increase the electrode conductivity; polyvinyl alcohol is a binder; HAT-CN-X is the main functional material of the electrode, so a certain proportion is needed. The quality of the acetylene black and the polyvinyl alcohol is increased, so that the electrode effect is influenced.

The invention also protects a membrane capacitive deionization module which sequentially comprises an organic glass plate, an electrode taking HAT-CN-X as an active substance, non-woven fabric, an anion exchange membrane, two silica gel gaskets, cation exchange, an electrode taking HAT-CN-X as an active substance and an organic glass plate.

The invention also provides a capacitance deionization method of the membrane capacitance deionization module, which comprises the following steps:

s3, forming a closed loop by the membrane capacitor deionization module and a direct current voltage circuit, and applying a voltage of 1.2-1.8V;

s4, sending a NaCl solution with the concentration of 500-1000 mg/L into a membrane capacitance deionization module, using an electrode made of HAT-CN-X material as a cathode/anode to adsorb ions, and then flowing out, wherein the flow rate of the NaCl solution is 22 mL/min;

s5, detecting the conductivity of the NaCl solution at the outlet of the capacitive deionization module in real time by adopting a conductivity probe to determine the adsorption capacity;

s6, after the electrode reaches the adsorption saturation, reversely connecting voltage for desorption;

s7, repeating the steps S3-S6, and carrying out the next capacitive deionization process.

Compared with the prior art, the invention has the beneficial effects that:

(1) the preparation method of the nitrogen-rich microporous carbon material adopts an in-situ synthesis HAT condensation method to prepare a novel hexagonal carbon skeleton, has rich heteroatom and side group contents and potential synergistic effect of C atoms and N atoms, is an ideal electrode for capacitive deionization, and has the characteristics of fast ion diffusion and strong charge transfer capacity. In addition, the HAT-CN material has the synergistic effect of large accessible surface area, large pore volume and high graphitization, so that the capacitive deionization performance is further enhanced.

(2) The membrane capacitance deionization module applied to the nitrogen-rich microporous carbon material can absorb more ions in the capacitance deionization process, and the HAT-CN electrode is carbonized at 550 ℃ and has the scanning rate of 5mV s^-1The specific capacitance in the 1M NaCl solution was 179.2F g-1. At 500mg L^-1A voltage of 1.2V was applied to the NaCl solution to obtain 24.66mg g^-1The high salt adsorption capacity of the catalyst shows good cycle stability at 30 cycles.

(3) The HAT-CN prepared by the invention has large specific surface area, rich micropore structure, good conductivity, sufficient charge storage space and active sites and higher MCDI performance. In addition, HAT-CN has high nitrogen content, good wettability and low impedance, which all accelerate the rapid transmission of salt ions, and HAT-CN electrode as heteroatom carbon material also has good regeneration performance, and is suitable for MCDI application and alkaline treatment.

Drawings

FIG. 1 shows a membrane capacitive deionization device, wherein (a) is an organic glass plate, (b) is an HAT-CN-X electrode, (c) is an anion exchange membrane, (d) is two silica gel gaskets, and (e) is a cation exchange membrane.

FIG. 2 is a flow chart of the CDI apparatus, wherein (computer (a), conductivity meter (b), water reservoir (c), peristaltic pump (d), DC power supply (e), capacitive deionization module (f))

FIG. 3 is a scanning electron micrograph and mapping of C and N, wherein (HAT-CN-450(a), HAT-CN-550(b), HAT-CN-700(C) and HAT-CN-800 (d)).

FIG. 4 is a nitrogen adsorption isotherm of a HAT-CN-450/550/700/800 electrode sample.

FIG. 5 is a pore size distribution of a HAT-CN-450/550/700/800 electrode sample.

FIG. 6 is a CV curve of 5mV/s scan for different electrodes.

FIG. 7 shows the specific capacitance of the HAT-CN-550 electrode, with a sweep rate of 1-50 mV/s.

FIG. 8 is a graph of conductivity versus deionization time for different electrodes

FIG. 9 shows the adsorption capacities of different materials.

FIG. 10 is a graph of the conductivity of the HAT-CN-550 electrode as a function of time at no-voltage.

FIG. 11 shows the amount of desalination at no voltage for the HAT-CN-550 electrode.

FIG. 12 is a graph of conductivity over time for NaCl solutions of different concentrations.

FIG. 13 is a graph showing the regeneration performance of HAT-CN-550 electrode

Detailed Description

The present invention will be further described with reference to specific embodiments, but the present invention is not limited to the examples in any way. The starting reagents employed in the examples of the present invention are, unless otherwise specified, those that are conventionally purchased.

Example 1

A nitrogen-rich microporous carbon material is prepared by the following method:

s1, synthesizing HAT, namely refluxing hexacyclohexane octahydrate (8g, 12.6mmol) and diaminocarbonitrile (22g, 100.8mmol) in glacial acetic acid (300mL) for 2h, filtering a black suspension while heating, washing with hot glacial acetic acid (3 × 25mL) to obtain a black solid, adding 30% HNO3(60mL) to the solid suspension, heating at 100 ℃ for 3h, pouring the hot dark brown suspension into ice water (200mL) for cooling overnight, filtering the suspension, refluxing the solid in acetonitrile (400mL) for 2h, filtering, evaporating the filtrate in vacuum to obtain an orange solid, namely the HAT, wherein the ratio of the amount of substances of the hexacyclohexane octahydrate and the diaminocarbonitrile is 1: 8;

s2, synthesizing HAT-CN-X:charring HAT as raw material at different temperatures for 1 hr under the action of nitrogen flow, and heating at 2 deg.C for 2 min^-1The temperature rising rate of the carbon material is increased from room temperature to 550 ℃, and the nitrogen-enriched microporous carbon material HAT-CN-500 is synthesized, wherein CN is the element type after carbonization.

Example 2

s1, synthesizing HAT, namely refluxing hexacyclohexane octahydrate and diaminocarbonitrile in glacial acetic acid (300mL) for 2h, filtering a black suspension when hot, washing with hot glacial acetic acid (3 × 25mL) to obtain a black solid, adding 30% HNO3(60mL) into the solid suspension, heating at 100 ℃ for 3h, pouring the hot dark brown suspension into ice water (200mL) for cooling overnight, filtering the suspension, refluxing the solid in acetonitrile (400mL) for 2h, filtering, evaporating the filtrate in vacuum to obtain an orange solid, namely HAT,

wherein the mass ratio of the hexacyclohexane octahydrate to the diaminocarbonitrile is 1: 2;

s2, synthesizing HAT-CN-X: charring HAT as raw material at different temperatures for 1 hr under nitrogen flow at 2 deg.C for min^-1The temperature rising rate of the carbon material is increased from room temperature to 450 ℃, and the nitrogen-enriched microporous carbon material HAT-CN-450 is synthesized, wherein CN is the element type after carbonization.

Example 3

wherein the mass ratio of the hexacyclohexane octahydrate to the diaminocarbonitrile is 1: 8;

s2, synthesizing HAT-CN-X: HAT is used as raw material, and is carbonized for 1h at different temperatures under the action of nitrogen flow, and the temperature is 2 DEG Cmin^-1The temperature rising rate of the carbon material is increased from room temperature to 700 ℃, and the nitrogen-enriched microporous carbon material HAT-CN-700 is synthesized, wherein CN is the element type after carbonization.

Example 4

s2, synthesizing HAT-CN-X: charring HAT as raw material at different temperatures for 1 hr under nitrogen flow at 2 deg.C for min^-1The temperature rising rate of the carbon material is increased from room temperature to 800 ℃, and the nitrogen-enriched microporous carbon material HAT-CN-800 is synthesized, wherein CN is the element type after carbonization.

Example 5

The membrane capacitance deionization electrode material is prepared by mixing HAT-CN-X, acetylene black and polyvinyl alcohol, wherein the mass ratio of HAT-CN-X, acetylene black and polyvinyl alcohol is 8:1: 1.

HAT-CN-450/550/700/800(800mg) was mixed with polyvinyl alcohol and carbon black and stirred for 2 h; coating the titanium mesh with a coating film thickness of 100-500 mu m, drying the coated titanium mesh at 45 ℃ for 2h, and then drying at 110 ℃ for 1 h; an electrode with HAT-CN-450/550/700/800 active material was obtained.

A membrane capacitive deionization module is assembled as shown in figure 1, and sequentially comprises an organic glass plate, an electrode taking HAT-CN-X as an active substance, non-woven fabrics, an anion exchange membrane, two silica gel gaskets, cation exchange, an electrode taking HAT-CN-X as an active substance and an organic glass plate.

The CDI apparatus described in fig. 2 was used to perform a capacitive deionization performance test on the membrane capacitive deionization module (f), and the specific steps of the capacitive deionization method were as follows:

s3, forming a closed loop by the membrane capacitor deionization module (f) and the direct current voltage circuit (e);

s4, sending NaCl solution with the concentration of 500mg/L into the membrane capacitance deionization module from the water tank (c) by using a peristaltic pump (d), and finally flowing back to the water tank (c);

and S5, detecting the conductivity of the NaCl solution at the outlet of the membrane capacitance deionization module in real time to determine the adsorption quantity.

S6, applying a voltage of 1.2V to the module to adsorb ions, and desorbing by reverse connection voltage, wherein the concentration of the NaCl solution is 500mg/L, the flow rate is 22mL/min, and the adsorption and desorption time is 120 min.

The capacitive deionization and desalination performance of the HAT-CN-450/550/700/800 material is shown in FIG. 8 and FIG. 9, respectively. For capacitive deionization, the amount of salt removed was 22.79, 24.66, 19.13 and 17.50mg/g at a voltage of 1.2V, 500mg/L NaCl solution flow rate of 22mL/min (FIG. 9).

A field emission scanning electron microscope of HAT-CN-450/550/700/800 material is shown in figure 3, and the stacking of some small regular hexagons and simple smooth surface, and the carbon and nitrogen distribution can be seen to be uniform on the mapping chart of carbon and nitrogen elements.

The nitrogen adsorption isotherm of the HAT-CN-450/550/700/800 electrode sample is shown in FIG. 4, and the material is a type I isotherm. At p/p0<At 0.1, there is a large amount of N₂Adsorbed, no further adsorption at p/p0 ═ 0.1 to 0.9, indicating that HAT-CN has almost unique microporosity properties.

Meanwhile, the pore size distribution of the HAT-CN-450/550/700/800 electrode sample is shown in figure 5, and the prepared inorganic non-porous sample is 600-800m²The specific surface area is higher in the range of/g, and the micropores are increased and the micropore volume is increased with the increase of the synthesis temperature. Finally, p/p0>The adsorption capacity at 0.9 comes from the adsorption on the wafer surface and in the wafer lamination chamber. The higher the microporous SSA, the more active sites adsorb ions. It is obvious thatHAT-CN-550 has a highly microporous structure, which is critical to its capacitive and deionizing properties.

CV curves for different electrodes at 5mV/s are shown in FIG. 6, and the capacitances (Cs) of the HAT-CN-450/550/700/800 electrodes were 52.25, 179.20, 162.54, and 99.86F/g, respectively.

The Cs for the HAT-CN-550 electrode was 87.76, 168.43, 179.20, and 221.28F/g at sweep rates of 50, 10, 5, 1mV/s, respectively, as shown in FIG. 7.

Example 6

The membrane capacitance deionization electrode material is prepared by mixing HAT-CN-550, acetylene black and polyvinyl alcohol, wherein the mass ratio of HAT-CN-550 to acetylene black to polyvinyl alcohol is 8:1: 1.

Mixing HAT-CN-550 mixed polyvinyl alcohol and carbon black, and stirring for 2 h; coating the titanium mesh with a coating film thickness of 100-500 mu m, drying the coated titanium mesh at 45 ℃ for 2h, and then drying at 110 ℃ for 1 h; an electrode containing HAT-CN-550 active material was obtained.

A membrane capacitance deionization module is assembled as shown in figure 1, and sequentially comprises an organic glass plate, an electrode taking HAT-CN-550 as an active substance, non-woven fabrics, an anion exchange membrane, two silica gel gaskets, cation exchange, an electrode taking HAT-CN-550 as an active substance and an organic glass plate.

S6, applying voltages of 1.2V, 1.6V and 1.8V to the module to adsorb ions, and performing desorption by reverse connection of voltage, wherein the concentration of the NaCl solution is 500mg/L, the flow rate is 22mL/min, and the adsorption and desorption time is 120 min.

The capacitive deionization and desalination performance of the HAT-CN-550 material is shown in FIGS. 10 and 11, respectively. For the capacitive deionization process, the desalting capacity of 500mg L-1NaCl solution at the flow rate of 22mL/min and the voltage of 1.2-1.8V is 24.66-33.17mg/g, which shows that higher voltage can generate stronger electrostatic action to bring larger desalting capacity.

Example 7

s4, sending NaCl solutions with the concentrations of 500, 700 and 800mg/L into the membrane capacitance deionization module from the water tank (c) by adopting a peristaltic pump (d), and finally flowing back to the water tank (c);

S6, applying a voltage of 1.2 to the module to adsorb ions, and desorbing by reverse connection voltage, wherein the concentration of the NaCl solution is 500mg/L, the flow rate is 22mL/min, and the adsorption and desorption time is 120 min.

The capacitive deionization and desalination performances of the HAT-CN-550 material are respectively shown in the attached figure 12. For capacitive deionization process, at a flow rate of 22mL/min, a voltage of 1.2V, the initial sodium chloride concentrations were 24.66, 26.43, and 30.79mg/g for desalination at 500, 700, and 800 mg/L. It is clear that the amount of electrosorption increases with increasing sodium chloride concentration, since the initial sodium chloride concentration increases, the ion concentration in the solution increases, the salt ions pass through the inter-electrode-distance channel at a faster transport speed, and the electrosorption capacity increases. However, when the amount of increase of ions in the solution is much larger than the amount of adsorption, the ion species in the pores are saturated, resulting in a decrease in removal efficiency.

Example 8

The recycling effect of HAT-CN-550 material is shown in FIG. 13. For the capacitive deionization process, the influence of the regeneration stability of the capacitive deionization process is studied under the conditions of flow rate of 22mL/min, voltage of 1.2V and initial sodium chloride concentration of 500mg/L, the adsorption capacity of the capacitive deionization process is revealed, and the electrode is desorbed in the case of short circuit. The deionization process was completed quickly after the voltage was applied, and the short circuit of the cell during discharge had a fast desorption performance, indicating that the HAT-CN-550 electrode had good regeneration performance.

In addition, after 30 regeneration cycles, the solution conductivity did not significantly decrease, showing good regeneration performance. Therefore, the HAT-CN-550 electrode has good deionization performance in CDI.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A preparation method of a nitrogen-rich microporous carbon material is characterized by comprising the following steps:

s1, synthesizing HAT: refluxing cyclohexane octahydrate and diaminocarbonitrile in glacial acetic acid for 1-8 h, filtering a black suspension while the solution is hot, washing the black suspension with hot glacial acetic acid to obtain a black solid, wherein the black solid is added with 30% by massHNO of (2)₃Or HNO₃Heating the mixture with HCl at 50-100 ℃ for 1-5 h, pouring the dark brown suspension into water at 0 ℃ for cooling and settling, filtering and collecting solids, refluxing the solids in acetonitrile for 1-4 h, filtering, and evaporating in vacuum to obtain orange solids, namely HAT;

2. The method for producing a nitrogen-rich microporous carbon material according to claim 1, wherein the mass ratio of hexacyclohexane octahydrate and diaminocarbonitrile in S1 is 1: 8.

3. The method for producing the nitrogen-rich microporous carbon material according to claim 1, wherein the carbonization temperature in S2 is 450 to 700 ℃, the carbonization time is 1 hour, and the temperature increase rate is 2 ℃ for min^-1。

4. The method for producing a nitrogen-rich microporous carbon material according to claim 3, wherein the carbonization temperature in S2 is 550 ℃, the carbonization time is 1 hour, and the temperature increase rate is 2 ℃ for min^-1。

5. A nitrogen-rich microporous carbon material prepared by the method for preparing a nitrogen-rich microporous carbon material according to any one of claims 1 to 4.

6. Use of the nitrogen-rich microporous carbon material of claim 5 in the preparation of membrane capacitive deionization electrode materials.

7. The membrane capacitance deionization electrode material is characterized by being prepared by mixing HAT-CN-X, acetylene black and polyvinyl alcohol according to claim 5, wherein the mass ratio of HAT-CN-X, acetylene black and polyvinyl alcohol is 8-6: 1-2.

8. The membrane capacitive deionization electrode material of claim 7 wherein the mass ratio of HAT-CN-X, acetylene black and polyvinyl alcohol is 8:1: 1.

9. A membrane capacitive deionization module, characterized in that the capacitive deionization module sequentially comprises an organic glass plate, an electrode using the HAT-CN-X of claim 5 as an active substance, non-woven fabrics, an anion exchange membrane, two silica gel gaskets, cation exchange, an electrode using the HAT-CN-X of claim 5 as an active substance, and an organic glass plate.

10. The method for capacitive deionization of a membrane capacitive deionization module as claimed in claim 9, comprising the steps of: