Preparation method and application of capacitive deionization anode applied to phosphate adsorption and desorption

Abstract

The invention discloses a preparation method and application of a capacitive deionization anode applied to phosphate adsorption and desorption, and belongs to the field of wastewater adsorption and enrichment of inorganic phosphorus. The invention aims to solve the problems of low phosphate adsorption capacity and difficulty in repeated use of an adsorbent or poorer conductivity of the existing adsorption material. The method comprises the following steps: 1, preparing a PEDOT / YMOF-NH2 composite material; and 2, preparing the capacitive deionization anode. According to the application, the adsorbent is used for adsorbing and desorbing phosphate in a phosphate-containing water body. The preparation method is used for preparing the capacitive deionization anode applied to phosphate adsorption and desorption.

Description

Technical Field

[0001] The present invention belongs to the field of wastewater adsorption and enrichment of inorganic phosphorus. Background Art

[0002] With the acceleration of the industrialization process and the rapid growth of the population, the global demand for efficient, low-cost and sustainable water treatment technologies is increasing day by day. Due to the ability of the electrochemical process to precisely regulate current and voltage, and its modular design and good scalability, it has gradually become a key technical direction in the field of environmental remediation. Especially in the removal and enrichment of phosphate, electrochemical technology shows significant advantages due to its controllability and high efficiency. Phosphorus (P), as an essential life element, its global reserves mainly rely on non-renewable phosphate rock, and it is expected to face serious depletion within the next century, thus triggering a phosphorus crisis, threatening food security and disrupting the phosphorus cycle in the ecosystem. To address the challenge of phosphorus resource depletion, currently widely used phosphorus removal technologies include precipitation method, ion exchange method, membrane separation, and capacitive deionization (CDI) technology, etc.

[0003] Capacitive deionization (CDI) technology has obtained a number of patent disclosures in phosphorus adsorption research due to its advantages of low energy consumption, high stability and no secondary pollution. Electrochemical technology has the advantages of precise control (such as current, voltage), low chemical reagent consumption and high long-term stability. As an emerging electro-assisted technology, CDI shows significant potential in phosphorus enrichment.

[0004] Although the current CDI technology mainly relies on carbon-based adsorbents such as activated carbon and graphene, these materials usually have low adsorption capacity and poor stability, resulting in difficult reuse of the adsorbent, thus limiting its popularization in practical applications. To improve the adsorption performance, researchers have gradually turned to composite materials with multifunctional characteristics, especially metal-organic frameworks (MOF), whose high porosity, adjustable pore size and excellent physical and chemical properties make it have significant application prospects in the field of phosphorus adsorption. However, due to the poor conductivity of MOF materials themselves, they have limitations when used as electrode materials in electrochemical applications. Summary of the Invention

[0005] The present invention aims to solve the problems that existing adsorption materials either have low phosphate adsorption capacity and difficult reuse of the adsorbent, or have poor conductivity, and further provides a preparation method and application of a capacitive deionization anode for phosphate adsorption and desorption.

[0006] A preparation method of a capacitive deionization anode for phosphate adsorption and desorption is carried out according to the following steps:

[0007] I. Prepare PEDOT / YMOF-NH2 composite material:

[0008] ① Dissolve YCl3 in a mixed solution of deionized water and glacial acetic acid, then add 3,4-ethylenedioxythiophene liquid and mix by ultrasonic to obtain Solution I;

[0009] ② Dissolve 2-aminoterephthalic acid in deionized water, then add sodium hydroxide for deprotonation reaction to obtain Solution II;

[0010] ③ Mix Solution I and Solution II, then react at room temperature for 10 h to 12 h to obtain Solution III;

[0011] ④ Drop the ethanol solution of FeCl3 into Solution III, and react at room temperature with a stirring speed of 450 rpm to 600 rpm for 4 h to 8 h to obtain black crystals;

[0012] ⑤ Wash and dry the black crystals to obtain the PEDOT / YMOF-NH2 composite material;

[0013] II. Preparation of the capacitive deionization anode:

[0014] Disperse the PEDOT / YMOF-NH2 composite material, carbon black and polyvinylidene fluoride in ethanol, then stir to obtain a slurry. Uniformly coat the slurry on the surface of carbon felt, and finally dry to obtain the carbon felt-supported PEDOT / YMOF-NH2 composite electrode, thus completing the preparation method of the capacitive deionization anode applied to phosphate adsorption and desorption.

[0015] An application of the capacitive deionization anode applied to phosphate adsorption and desorption, which is used for adsorbing and desorbing phosphate in the phosphate-containing water body.

[0016] The beneficial effects of the present invention are:

[0017] The present invention provides a method for preparing an anode based on a PEDOT / YMOF-NH2 composite material and its application in capacitive deionization. By introducing poly(3,4-ethylenedioxythiophene) (PEDOT) into the pore structure of amino-functionalized yttrium-based metal-organic framework (YMOF-NH2), a composite material with a large specific surface area and high conductivity is prepared, named PEDOT / YMOF-NH2. The synthesis process utilizes 3,4-ethylenedioxythiophene, yttrium trichloride, 2-aminoterephthalic acid and a solvent, involving various chemical reactions such as monomer assembly, oxidative polymerization and topological embedding. Using this composite material, PEDOT / YMOF-NH2, carbon black (to improve conductivity) and polyvinylidene fluoride (to improve adhesion) are mixed in ethanol and coated on the surface of carbon felt to prepare a carbon felt-supported PEDOT / YMOF-NH2 electrode. Using this as the capacitive deionization anode, a capacitive deionization device is constructed for efficient adsorption and enrichment of phosphate under electrochemical regulation. At the same time, the electrode exhibits excellent stability in the adsorption and desorption cycles of phosphate, effectively overcoming the deficiencies of traditional carbon-based electrodes in terms of capacity and regeneration performance. The specific principle is as follows:

[0018] PEDOT has excellent electrical conductivity, which can significantly improve the overall conductivity of YMOF-NH2. YMOF-NH2 has a good pore structure and a large specific surface area, which can provide sufficient adsorption sites; while the excellent conductivity of PEDOT ensures efficient electron transfer during the capacitive deionization process, thus significantly improving the performance of the composite material in electrochemical reactions. Under the action of electrochemistry, the PEDOT / YMOF-NH2 composite material can effectively adsorb phosphate ions in water. When a voltage is applied, the charges in the composite material interact with the phosphate ions in water, causing the phosphate to adsorb on the electrode surface. When a reverse voltage is applied, the phosphate ions will quickly desorb from the electrode surface, thus realizing the adsorption and desorption cycle process. Compared with the traditional chemical adsorption method, this process has higher controllability and lower energy consumption. Brief Description of the Drawings

[0019] Figure 1 XRD patterns of the PEDOT / YMOF-NH2 composite material prepared in Step 1 of Example 1 and the YMOF-NH2 composite material prepared in Step 1 of Comparative Experiment 1;

[0020] Figure 2 FT-IR spectra of the PEDOT / YMOF-NH2 composite material prepared in Step 1 of Example 1 and the YMOF-NH2 composite material prepared in Step 1 of Comparative Experiment 1;

[0021] Figure 3XPS spectra of the PEDOT / YMOF-NH2 composite material prepared in Step 1 of Example 1 and the YMOF-NH2 composite material prepared in Step 1 of the comparative experiment. (a) is the full spectrum, and (b) is the characteristic peak spectrum;

[0022] Figure 4 EPR diagrams of the PEDOT / YMOF-NH2 composite material prepared in Step 1 of Example 1 and the YMOF-NH2 composite material prepared in Step 1 of the comparative experiment;

[0023] Figure 5 Conductivity test curves of the PEDOT / YMOF-NH2 composite material prepared in Step 1 of Example 1 and the YMOF-NH2 composite material prepared in Step 1 of the comparative experiment;

[0024] Figure 6 TEM diagrams of the PEDOT / YMOF-NH2 composite material prepared in Step 1 of Example 1 and the YMOF-NH2 composite material prepared in Step 1 of the comparative experiment;

[0025] Figure 7 SEM diagrams of the carbon felt-supported PEDOT / YMOF-NH2 composite electrode prepared in Step 2 of Example 1 and the carbon felt-supported YMOF-NH2 composite electrode prepared in Step 2 of the comparative experiment;

[0026] Figure 8 Cyclic voltammetry (CV) diagrams and galvanostatic charge-discharge (GCD) diagrams of the carbon felt-supported PEDOT / YMOF-NH2 composite electrode prepared in Step 2 of Example 1 or the carbon felt-supported YMOF-NH2 composite electrode prepared in Step 2 of the comparative experiment. (a) is the CV diagram at a test rate of 10 mV / s, and (b) is the GCD diagram at a current density of 1 A / g;

[0027] Figure 9 Schematic diagram and physical diagram of the capacitive deionization device in Step 1 of Example 2. (a) is the schematic diagram of the connection between the capacitive deionization device, peristaltic pump, electrochemical workstation, and container, (b) is the physical diagram of the capacitive deionization device, and (c) is the internal structure diagram of the capacitive deionization device;

[0028] Figure 10For Example 2 and Comparative Experiment 2, under different external electric field conditions, the changes in phosphate concentration during the electro-assisted adsorption and desorption processes were carried out using the carbon felt-supported PEDOT / YMOF-NH2 composite electrode and the carbon felt-supported YMOF-NH2 composite electrode. (a) Phosphate concentration changes under 0 V condition, (b) Phosphate concentration changes under the conditions of 0.8 V adsorption and -0.8 V desorption, (c) Phosphate concentration changes under the conditions of 1.2 V adsorption and -1.2 V desorption, (d) Phosphate concentration changes under the conditions of 1.6 V adsorption and -1.6 V desorption;

[0029] Figure 11 For Example 2, under different applied voltage conditions, the electro-assisted phosphate adsorption capacity and the changes in adsorption capacity during five cycles of adsorption and desorption were carried out using the carbon felt-supported PEDOT / YMOF-NH2 composite electrode. (a) Bar chart of adsorption capacity under the applied voltage conditions from 0 V to 1.6 V, (b) Graph of the changes in adsorption capacity during five cycles of adsorption and desorption;

[0030] Figure 12 For Example 2, under different external electric field conditions, the changes in the adsorbed phosphate mass and the adsorbed mass during five cycles of adsorption and desorption were carried out using the carbon felt-supported PEDOT / YMOF-NH2 composite electrode. (a) Bar chart of adsorption and desorption mass under the applied voltage conditions from 0 V to 1.6 V, (b) Graph of the changes in adsorption and desorption mass during five cycles of adsorption and desorption;

[0031] Figure 13 For Example 2 and Comparative Experiment 2, the comprehensive evaluation indexes of the carbon felt-supported PEDOT / YMOF-NH2 composite electrode and the carbon felt-supported YMOF-NH2 composite electrode are as follows: (a) Phosphate enrichment rate, (b) Energy consumption, (c) Phosphate recovery rate, (d) Concentration factor. Specific implementation mode

[0032] Specific implementation mode 1: A preparation method of a capacitive deionization anode applied to phosphate adsorption and desorption is carried out according to the following steps:

[0033] 1. Preparation of PEDOT / YMOF-NH2 composite material:

[0034] ① Dissolve YCl3 in a mixed solution of deionized water and glacial acetic acid, then add 3,4-ethylenedioxythiophene liquid and mix by ultrasonic to obtain Solution I;

[0035] ② Dissolve 2-aminoterephthalic acid in deionized water, then add sodium hydroxide for deprotonation reaction to obtain Solution II;

[0036] ③Mix Solution I and Solution II, and then react at room temperature for 10 h to 12 h to obtain Solution III;

[0037] ④Drop the ethanol solution of FeCl3 into Solution III, and react at room temperature with a stirring speed of 450 rpm to 600 rpm for 4 h to 8 h to obtain black crystals;

[0038] ⑤Wash and dry the black crystals to obtain the PEDOT / YMOF-NH2 composite material;

[0039] II. Preparation of the capacitive deionization anode:

[0040] Disperse the PEDOT / YMOF-NH2 composite material, carbon black, and polyvinylidene fluoride in ethanol, then stir to obtain a slurry, uniformly coat the slurry on the surface of the carbon felt, and finally dry to obtain the carbon felt-supported PEDOT / YMOF-NH2 composite electrode, thus completing the preparation method of the capacitive deionization anode applied to phosphate adsorption and desorption.

[0041] The beneficial effects of this embodiment are as follows:

[0042] This embodiment provides an anode preparation method based on the PEDOT / YMOF-NH2 composite material and its application in capacitive deionization. By introducing poly(3,4-ethylenedioxythiophene) (PEDOT) into the pore structure of the amino-functionalized yttrium-based metal-organic framework (YMOF-NH2), a composite material with a large specific surface area and high conductivity is prepared, named PEDOT / YMOF-NH2. The synthesis process uses 3,4-ethylenedioxythiophene, yttrium trichloride, 2-aminoterephthalic acid, and a solvent, involving various chemical reactions such as monomer assembly, oxidative polymerization, and topological embedding. Using this composite material, PEDOT / YMOF-NH2, carbon black (to improve conductivity), and polyvinylidene fluoride (to improve adhesion) are mixed in ethanol and coated on the surface of the carbon felt to prepare the carbon felt-supported PEDOT / YMOF-NH2 electrode. Using it as the capacitive deionization anode, a capacitive deionization device is constructed for efficient adsorption and enrichment of phosphate under electrochemical regulation. At the same time, the electrode exhibits excellent stability in the adsorption and desorption cycles of phosphate, effectively overcoming the deficiencies of traditional carbon-based electrodes in capacity and regeneration performance. The specific principle is as follows:

[0043] PEDOT has excellent electrical conductivity, which can significantly improve the overall conductivity of YMOF-NH2. YMOF-NH2 has a good pore structure and a large specific surface area, which can provide sufficient adsorption sites; while the excellent conductivity of PEDOT ensures efficient electron transport during the capacitive deionization process, thus significantly improving the performance of the composite material in the electrochemical reaction. Under the action of electrochemistry, the PEDOT / YMOF-NH2 composite material can effectively adsorb phosphate ions in water. When a voltage is applied, the charges in the composite material interact with the phosphate ions in water, causing the phosphate to adsorb on the electrode surface. When a reverse voltage is applied, the phosphate ions will quickly desorb from the electrode surface, thus realizing the cycle of adsorption and desorption. Compared with the traditional chemical adsorption method, this process has higher controllability and lower energy consumption.

[0044] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that: in step ①, the mass ratio of YCl3 to the volume of the mixed solution of deionized water and glacial acetic acid is 1 g:(15 - 18) mL; in the mixed solution of deionized water and glacial acetic acid in step ①, the volume ratio of deionized water to glacial acetic acid is 1:(0.07 - 0.1); in step ①, the mass ratio of YCl3 to 3,4-ethylenedioxythiophene liquid is 1:(2.0 - 2.3); in step ①, the ultrasonic mixing is specifically carried out under the condition of a power of 450 W - 600 W for 25 min - 30 min. Others are the same as Specific Embodiment 1.

[0045] Specific Embodiment 3: The difference between this embodiment and either Specific Embodiment 1 or 2 is that: in step ②, the mass ratio of 2-aminoterephthalic acid to the volume of deionized water is 1 g:(38 - 40) mL; in step ②, the mass ratio of 2-aminoterephthalic acid to sodium hydroxide is 1:(0.4 - 0.5); in step ②, the deprotonation reaction is specifically carried out at room temperature and a stirring speed of 450 rpm - 600 rpm for 25 min - 30 min. Others are the same as Specific Embodiment 1 or 2.

[0046] Specific Embodiment 4: The difference between this embodiment and any one of Specific Embodiments 1 to 3 is that: in step ③, the volume ratio of Solution Ⅰ to Solution Ⅱ is 1:(2.3 - 2.5). Others are the same as Specific Embodiment 3.

[0047] Specific Embodiment 5: The difference between this embodiment and any one of Specific Embodiments 1 to 4 is that: in step ④, the volume ratio of the ethanol solution of FeCl3 to Solution Ⅲ is 1:(3.35 - 3.5); the concentration of the ethanol solution of FeCl3 in step ④ is 0.5 mol / L - 1 mol / L. Others are the same as Specific Embodiments 1 to 4.

[0048] Embodiment Six: The difference between this embodiment and any one of Embodiments One to Five is as follows: The washing and drying in Step ①⑤ are specifically carried out according to the following steps: Alternately use deionized water and absolute ethanol solution to wash repeatedly until the washing liquid is colorless, and then under the condition of a temperature of 60°C to 70°C, perform vacuum drying for 10h to 14h. Others are the same as those in Embodiments One to Five.

[0049] Embodiment Seven: The difference between this embodiment and any one of Embodiments One to Six is as follows: The mass ratio of the PEDOT / YMOF-NH2 composite material to carbon black in Step ② is (8 to 8.5):1; the mass ratio of the carbon black to polyvinylidene fluoride in Step ② is 1:(1 to 1.5); the mass ratio of the PEDOT / YMOF-NH2 composite material to the volume of ethanol in Step ② is 1g:(400 to 500) mL; the coating thickness of the slurry in Step ② is 0.02mm to 0.05mm; the drying in Step ② is specifically under the condition of a temperature of 60°C to 70°C, perform vacuum drying for 10h to 14h. Others are the same as those in Embodiments One to Six.

[0050] Embodiment Eight: An application of a capacitive deionization anode for phosphate adsorption and desorption, which is used for adsorbing and desorbing phosphates in a phosphate-containing water body.

[0051] Embodiment Nine: The difference between this embodiment and Embodiment Eight is as follows: The adsorption and desorption of phosphates in the phosphate-containing water body are specifically carried out according to the following steps:

[0052] 1. Use a carbon felt-supported PEDOT / YMOF-NH2 composite electrode as the capacitive deionization anode, and a carbon felt-supported carboxylated activated carbon electrode as the capacitive deionization cathode. Assemble the sealing plate, capacitive deionization anode, anion exchange membrane, gasket, capacitive deionization cathode, and sealing plate in sequence from one side to the other side, and control the distance between the anion exchange membrane and the capacitive deionization cathode to be 2mm to 5mm through the gasket. Set the water inlet on the sealing plate on the capacitive deionization anode side, and set the water outlet on the sealing plate on the capacitive deionization cathode side to obtain a capacitive deionization device;

[0053] 2. Connect the capacitive deionization anode and the capacitive deionization cathode to the positive and negative electrodes of the power supply respectively. Use the phosphate-containing water body as the water to be treated, introduce the water to be treated into the capacitive deionization device from the water inlet and circulate it. Adsorb under the conditions of an applied voltage of 0.8V to 1.6V and an effluent flow rate of 12mL / min to 15mL / min;

[0054] The concentration of phosphate in the phosphate-containing water body is 10 mg / L to 500 mg / L, and the pH value is 6 to 10;

[0055] Third, connect the capacitive deionization anode and the capacitive deionization cathode to the negative and positive poles of the power supply respectively to reverse the electrode polarity. Use a sodium hydroxide solution with a concentration of 0.01 mol / L to 0.02 mol / L as the eluent. Pass the eluent into the capacitive deionization device from the water inlet and circulate it. Under the conditions of an applied voltage of -0.8 V to -1.6 V and an outlet flow rate of 12 mL / min to 15 mL / min, desorb for 0.5 h to 2 h. The others are the same as in the eighth specific embodiment.

[0056] In this specific embodiment, the water inlet is arranged on the sealing plate on the anode side, so that the phosphate-containing water body first passes through the anode treatment; and the water outlet is arranged on the sealing plate of the cathode, so that the water body is discharged after passing through the cathode treatment.

[0057] The adsorption process of this specific embodiment includes: storing the phosphate-containing water body in a container, transporting the solution to the capacitive deionization device through a peristaltic pump, and after the anode adsorbs the phosphate, returning the treated solution to the container, thereby completing the adsorption process of phosphorus in the phosphorus-containing water body.

[0058] The desorption process of this specific embodiment includes: replacing the new container containing the sodium hydroxide solution, transporting the solution to the capacitive deionization device through a peristaltic pump, and under the action of the reverse electric field, desorbing the previously adsorbed phosphate and enriching it in the sodium hydroxide solution, and finally returning the treated solution to the container to complete the enrichment process of the phosphate.

[0059] Tenth specific embodiment: The difference between this embodiment and one of the eighth or ninth specific embodiments is that the carboxylated activated carbon electrode supported on the carbon felt described in step one is specifically prepared according to the following steps:

[0060] ① Disperse activated carbon in deionized water, stir at room temperature with a stirring speed of 450 rpm to 600 rpm for 20 min to 30 min, then filter, repeat the dispersion and filtration until the conductivity of the filtrate is lower than 10 μS / cm, and then vacuum dry at a temperature of 60 °C to 70 °C for 6 h to 12 h to obtain pretreated activated carbon. Add nitric acid solution to the pretreated activated carbon, stir and heat at a temperature of 60 °C to 80 °C and a stirring speed of 450 rpm to 600 rpm for 65 h to 70 h, filter after the reaction, and repeatedly wash with deionized water until the washing liquid is neutral, and finally vacuum dry at a temperature of 60 °C to 70 °C for 5 h to 10 h to obtain carboxylated activated carbon; the concentration of the nitric acid solution is 7.6 mol / L to 8 mol / L; the mass ratio of the pretreated activated carbon to the volume of the nitric acid solution is 1 g:(8 - 10) mL;

[0061] ② Disperse carboxylated activated carbon, carbon black and polyvinylidene fluoride in ethanol, then stir to obtain a slurry, uniformly coat the slurry on the surface of carbon felt according to a coating thickness of 0.02 mm to 0.05 mm, and finally vacuum dry at a temperature of 65 °C to 80 °C for 5 h to 12 h to obtain a carbon felt-supported carboxylated activated carbon electrode; the mass ratio of the carboxylated activated carbon to the carbon black is (8 - 8.5):1; the mass ratio of the carbon black to the polyvinylidene fluoride is 1:(1 - 1.5); the mass ratio of the carboxylated activated carbon to the volume of ethanol is 1 g:(66 - 70) mL. Others are the same as in Embodiment VIII or IX.

[0062] The following examples are used to verify the beneficial effects of the present invention:

[0063] Example 1:

[0064] A preparation method of a capacitive deionization anode applied to phosphate adsorption and desorption, which is carried out according to the following steps:

[0065] I. Prepare PEDOT / YMOF-NH2 composite material:

[0066] ① Dissolve 0.976 g of YCl3 in a mixed solution of deionized water and glacial acetic acid, then add 2.18 g of 3,4-ethylenedioxythiophene liquid, and ultrasonically mix for 30 min under the condition of a power of 450 W to obtain Solution I;

[0067] The mixed solution of deionized water and glacial acetic acid is composed of 14 mL of deionized water and 1 mL of glacial acetic acid;

[0068] ② Dissolve 0.906 g of 2-aminoterephthalic acid in 35 mL of deionized water, then add 0.4 g of sodium hydroxide, and under the conditions of room temperature and a stirring speed of 600 rpm, carry out the deprotonation reaction for 30 min to obtain Solution II;

[0069] ③ Mix 15 mL of Solution I with 35 mL of Solution II, and then react at room temperature for 10 h to obtain Solution III;

[0070] ④ Drop 15 mL of the ethanol solution of FeCl3 into 50 mL of Solution III, and under the conditions of room temperature and a rotation speed of 600 rpm, react for 8 h to obtain black crystals;

[0071] The concentration of the ethanol solution of FeCl3 described is 0.5 mol / L;

[0072] ⑤ Alternately use deionized water and anhydrous ethanol solution to repeatedly wash the black crystals until the washing liquid is colorless, and then under the condition of a temperature of 60 °C, carry out vacuum drying for 14 h to obtain the PEDOT / YMOF-NH2 composite material;

[0073] II. Preparation of the capacitive deionization anode:

[0074] Disperse 0.06 g of the PEDOT / YMOF-NH2 composite material, carbon black, and polyvinylidene fluoride in ethanol, and then under the condition of a stirring speed of 600 rpm, stir for 30 min to obtain a slurry. According to a coating thickness of 0.02 mm, uniformly coat the slurry on the surface of a carbon felt (3 cm × 3 cm × 2 mm), and finally under the condition of a temperature of 60 °C, carry out vacuum drying for 10 h to obtain the carbon felt-supported PEDOT / YMOF-NH2 composite electrode;

[0075] The mass ratio of the PEDOT / YMOF-NH2 composite material to carbon black is 8:1; the mass ratio of carbon black to polyvinylidene fluoride is 1:1; the mass of the PEDOT / YMOF-NH2 composite material to the volume of ethanol is 1 g:400 mL.

[0076] Comparative Experiment 1: The difference between this comparative experiment and Example 1 is that: in Step ① of Step 1, the addition of 3,4-ethylenedioxythiophene liquid is omitted; in Step ⑤ of Step 1, the YMOF-NH2 composite material is obtained; in Step 2, the carbon felt-supported YMOF-NH2 composite electrode is obtained. Others are the same as in Example 1.

[0077] Figure 1XRD patterns of the PEDOT / YMOF-NH2 composite material prepared in Step 1 of Example 1 and the YMOF-NH2 composite material prepared in Step 1 of the comparative experiment; the simulated YMOF-NH2 in the figure is to verify the crystal data of the standard YMOF-NH2 by comparing the crystal database data of the Materials Studio software, thereby proving that the materials prepared in the examples are accurate; as can be seen from the figure, its diffraction peaks are consistent with the spectra of PEDOT and YMOF-NH2, indicating that PEDOT / YMOF-NH2 maintains its main crystal structure. It does not match the structure of Fe-MOF (CCDC card number: 640536) or Y3Fe5O 12 (ICDD card number: 01-070-0953), indicating that Fe 3+ only exists as an oxidant during the in-situ polymerization process and does not form a coordination compound with 2-aminoterephthalic acid (C8H7NO4).

[0078] Figure 2 FT-IR spectra of the PEDOT / YMOF-NH2 composite material prepared in Step 1 of Example 1 and the YMOF-NH2 composite material prepared in Step 1 of the comparative experiment; H-O-H vibrations attributed to adsorbed water molecules were observed at 1550 cm -1 and 3300 cm -1 ~3481 cm -1 PEDOT / YMOF-NH2 exhibits characteristic absorption peaks of YMOF-NH2, located at 1255 cm -1 C-N stretching vibration in the amino group (-NH2), 702 cm -1 out-of-plane bending vibration of C-H in the aromatic ring, and 1432 cm -1 and 1382 cm -1 C-O stretching vibration in the carboxyl group (-COOH). PEDOT / YMOF-NH2 also exhibits characteristic peaks of PEDOT, including 1087 cm -1 C-O-C stretching vibration in methylenedioxy (-O-CH2-O-), 485 cm -1 C-S stretching vibration in the thiophene ring, and 407 cm -1 C-S-C bending vibration.

[0079] Figure 3XPS spectra of the PEDOT / YMOF-NH2 composite material prepared in Step 1 of Example 1 and the YMOF-NH2 composite material prepared in Step 1 of the comparative experiment. (a) is the full spectrum, and (b) is the characteristic peak diagram. As can be seen from the figure, the full spectrum of PEDOT / YMOF-NH2 has characteristic peaks of C1s, O 1s, N 1s, and S2p, indicating the successful preparation of the composite material. Figure (b) shows that the obvious N1s and S2p characteristic peaks in the PEDOT / YMOF-NH2 composite material indicate that PEDOT has been successfully embedded in the pore structure of YMOF-NH2.

[0080] Figure 4 EPR diagrams of the PEDOT / YMOF-NH2 composite material prepared in Step 1 of Example 1 and the YMOF-NH2 composite material prepared in Step 1 of the comparative experiment; YMOF-NH2 shows a strong signal at a g-factor of 2.005, indicating that it has a high concentration of oxygen vacancies. In contrast, the signal intensity of PEDOT / YMOF-NH2 at the same g-factor is significantly reduced, indicating a decrease in the oxygen vacancy concentration. The results also show that PEDOT has been successfully embedded in the pore structure of YMOF-NH2.

[0081] Figure 5 Conductivity test curves of the PEDOT / YMOF-NH2 composite material prepared in Step 1 of Example 1 and the YMOF-NH2 composite material prepared in Step 1 of the comparative experiment; Conductivity tests show that YMOF-NH2 itself has insulating properties, and its conductivity is about 10 -8 S / cm, while the conductivity of bulk PEDOT is about 10 -5 S / cm. The conductivity of the PEDOT / YMOF-NH2 composite material has been significantly increased by 3 to 4 orders of magnitude, reaching 10 -4 S / cm, especially under high-pressure (25 - 30 MPa) conditions, the performance is more significant.

[0082] Figure 6 TEM diagrams of the PEDOT / YMOF-NH2 composite material prepared in Step 1 of Example 1 and the YMOF-NH2 composite material prepared in Step 1 of the comparative experiment; Figure (a) shows the TEM image of the YMOF-NH2 composite material, showing its lamellar structure with clear edges, consisting of stacked multi-layered sheet structures, and the size is about 150 nm. Figure (b) shows the TEM image of the PEDOT / YMOF-NH2 composite material, where the arrow indicates the fibrous structure with dark contrast in the YMOF-NH2 matrix.

[0083] Figure 7SEM images of the carbon felt-supported PEDOT / YMOF-NH2 composite electrode prepared in Step 2 of Example 1 and the carbon felt-supported YMOF-NH2 composite electrode prepared in Step 2 of the comparative experiment. It was observed that the surface of the CF was relatively smooth, and YMOF-NH2 formed a multi-layered flaky structure on the CF, but did not completely cover the fibers. At a higher magnification, it can be seen that YMOF-NH2 covered a larger area of the CF, and the arrows marked the interface where YMOF-NH2 adhered to the CF surface, indicating that it was deposited in the form of a thin film. Compared with YMOF-NH2, PEDOT / YMOF-NH2 formed a thicker film on the CF, and its edges were rounded and smooth. Further magnification revealed that the PEDOT / YMOF-NH2 coating was more uniform and had a higher coverage of the CF surface, and the arrows marked the attachment area.

[0084] In the electrochemical tests, the carbon felt-supported PEDOT / YMOF-NH2 composite electrode prepared in Step 2 of Example 1 or the carbon felt-supported YMOF-NH2 composite electrode prepared in Step 2 of the comparative experiment was used as the working electrode, the reference electrode was a saturated calomel electrode (SCE), and the counter electrode was a carboxylated activated carbon electrode (the preparation method was as in Step 1 of Example 2). The tests were carried out at room temperature, in air, and in a 1 M H2SO4 electrolyte. The potential window of cyclic voltammetry (CV) was set from 0.1 V to 0.8 V, and the scanning rate range was from 5 mV / s to 100 mV / s. The potential window of galvanostatic charge-discharge (GCD) tests was from 0 V to 1 V, and the current density range was from 0.5 A / g to 5 A / g. All electrochemical tests were independently repeated three times to ensure the reproducibility of the results.

[0085] Figure 8 Cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) plots of the carbon felt-supported PEDOT / YMOF-NH2 composite electrode prepared in Step 2 of Example 1 or the carbon felt-supported YMOF-NH2 composite electrode prepared in Step 2 of the comparative experiment. (a) is the CV plot at a test rate of 10 mV / s, and (b) is the GCD plot at a current density of 1 A / g; the area of the CV curve of PEDOT / YMOF-NH2 was significantly larger than that of YMOF-NH2, which highlighted the important role of the electroactive polymer PEDOT in improving the performance of MOFs with poor conductivity. Figure (b) shows that compared with pure YMOF-NH2 (the charge-discharge time at 1 A / g was 16 s), the charge-discharge time of the PEDOT / YMOF-NH2 composite material was extended to 27.5 s at the same current density, significantly improving its energy storage capacity. These results further demonstrated that the introduction of PEDOT effectively improved the electrochemical performance of the composite material, especially its advantages in capacitive deionization applications.

[0086] Example 2:

[0087] An application of a capacitive deionization anode for phosphate adsorption and desorption. It is used for adsorbing and desorbing phosphate in a phosphate-containing water body, and specifically proceeds according to the following steps:

[0088] I. Using a carbon felt-supported PEDOT / YMOF-NH2 composite electrode as the capacitive deionization anode and a carbon felt-supported carboxylated activated carbon electrode as the capacitive deionization cathode, assemble the acrylic sealing plate, capacitive deionization anode, anion exchange membrane, polymethyl methacrylate gasket, capacitive deionization cathode, and acrylic sealing plate in sequence from one side to the other side. And control the distance between the anion exchange membrane and the capacitive deionization cathode to be 2 mm through the gasket. The water inlet is arranged on the sealing plate on the capacitive deionization anode side, and the water outlet is arranged on the sealing plate on the capacitive deionization cathode side to obtain a capacitive deionization device;

[0089] The anion exchange membrane is an AMI-7001S anion exchange membrane, purchased from Hangzhou Huamo Technology Co., Ltd.;

[0090] II. Connect the capacitive deionization anode and the capacitive deionization cathode to the positive and negative electrodes of the power supply respectively. Using 250 mL of phosphate-containing water body as the water body to be treated, introduce the water body to be treated into the capacitive deionization device through the water inlet and circulate it. Under the conditions of an applied voltage of 0 V to 1.6 V and an effluent flow rate of 12 mL / min, adsorb for 60 min;

[0091] The concentration of phosphate in the phosphate-containing water body is 50 mg / L, and the pH value is 7;

[0092] III. Connect the capacitive deionization anode and the capacitive deionization cathode to the negative and positive electrodes of the power supply respectively to reverse the electrode polarity. Using 50 mL of sodium hydroxide solution with a concentration of 0.01 mol / L as the eluent, introduce the eluent into the capacitive deionization device through the water inlet and circulate it. Under the conditions of an applied voltage of 0 V to -1.6 V and an effluent flow rate of 12 mL / min, desorb for 2 h;

[0093] The carbon felt-supported carboxylated activated carbon electrode described in step I is specifically prepared according to the following steps:

[0094] ① Disperse 10 g of activated carbon in 300 mL of deionized water. Under the conditions of room temperature and a stirring speed of 600 rpm, stir for 20 min, then filter. Repeat the dispersion and filtration until the conductivity of the filtrate is lower than 10 μS / cm. Then, under the condition of a temperature of 70 °C, vacuum dry for 6 h to obtain the pretreated activated carbon. Add 80 mL of nitric acid solution to 10 g of the pretreated activated carbon. Under the conditions of a temperature of 60 °C and a stirring speed of 600 rpm, stir and heat for 65 h. After the reaction, filter and wash repeatedly with deionized water until the washing liquid is neutral. Finally, under the condition of a temperature of 60 °C, vacuum dry for 5 h to obtain carboxylated activated carbon; the concentration of the nitric acid solution is 7.6 mol / L;

[0095] ② Disperse the carboxylated activated carbon, carbon black, and polyvinylidene fluoride in ethanol, and then under the condition of a stirring speed of 600 rpm, stir for 30 min to obtain a slurry. According to a coating thickness of 0.02 mm, uniformly coat the slurry on the surface of a carbon felt (3 cm × 3 cm × 2 mm). Finally, under the condition of a temperature of 60 °C, vacuum dry for 5 h to obtain a carbon felt-supported carboxylated activated carbon electrode; the mass ratio of the carboxylated activated carbon to carbon black is 8:1; the mass ratio of carbon black to polyvinylidene fluoride is 1:1; the mass ratio of the carboxylated activated carbon to the volume of ethanol is 1 g:66 mL.

[0096] Comparative Experiment 2: The difference between this comparative experiment and Example 2 is that the carbon felt-supported PEDOT / YMOF-NH2 composite electrode in Step 1 is replaced with the carbon felt-supported YMOF-NH2 composite electrode prepared in Comparative Experiment 1. Others are the same as in Example 2.

[0097] Figure 9 Figures (a), (b), and (c) are the schematic diagram and physical diagram of the capacitive deionization device in Step 1 of Example 2. (a) is the schematic diagram of the connection of the capacitive deionization device with a peristaltic pump, an electrochemical workstation, and a container. (b) is the physical diagram of the capacitive deionization device. (c) is the internal structure diagram of the capacitive deionization device. (a) shows the overall design of the system, including the electrode position, fluid channel, and power connection method. (b) details the installation of the carbon felt-supported PEDOT / YMOF-NH2 composite electrode and its connection with the reactor. (c) focuses on the design of the electric field distribution and liquid flow path to optimize the adsorption and desorption process of phosphorus.

[0098] Use the capacitive deionization device assembled in Example 2 to evaluate the adsorption and desorption performance of the carbon felt-supported PEDOT / YMOF-NH2 composite electrode and the carbon felt-supported YMOF-NH2 composite electrode for phosphate under different voltage conditions.

[0099] (1) Baseline test under a 0 V flow system:

[0100] Without an external electric field (0 V), a phosphate solution (50 mg / L, pH = 7) was used as the treatment solution and continuously operated for 60 min. The residual phosphate concentration in the system after 60 min of adsorption was recorded.

[0101] Without an external electric field (0 V), 0.01 M NaOH solution was used as the eluent and continuously operated for 120 min. The change in the phosphate concentration in the elution solution was recorded.

[0102] (2) Positive electric field-assisted adsorption test:

[0103] Under positive voltage electric fields (0.8 V, 1.2 V, and 1.6 V), a phosphate solution (50 mg / L, pH = 7) was used as the treatment solution and continuously operated for 60 min. At each test point, the residual phosphate concentration in the solution at the end of adsorption was recorded, and the adsorption capacity was fitted based on the residual concentration data.

[0104] (3) Negative electric field-assisted adsorption test:

[0105] Under negative voltage electric fields (-0.8 V, -1.2 V, and -1.6 V), 0.01 M NaOH solution was used as the eluent and continuously operated for 120 min. The change in the phosphate concentration in the elution solution was recorded.

[0106] Figure 10 For Example 2 and Comparative Experiment 2, the changes in phosphate concentration during the electro-assisted adsorption and desorption processes using the PEDOT / YMOF-NH2 composite electrode loaded on carbon felt and the YMOF-NH2 composite electrode loaded on carbon felt under different external electric field conditions are shown. (a) Phosphate concentration change under 0 V condition, (b) Phosphate concentration change under 0.8 V adsorption and -0.8 V desorption conditions, (c) Phosphate concentration change under 1.2 V adsorption and -1.2 V desorption conditions, (d) Phosphate concentration change under 1.6 V adsorption and -1.6 V desorption conditions.

[0107] Figure 10 (a) shows that after 60 min of adsorption, the residual phosphate concentration of the PEDOT / YMOF-NH2-based electrode was 19.40 mg / L, while that of the YMOF-NH2 electrode was 18.70 mg / L. In addition, under the same conditions, 0.01 M NaOH was used for phosphate desorption for 120 min, and only 4.07 mg / L of phosphate was eluted from the PEDOT / YMOF-NH2 electrode.

[0108] Figure 10(b) shows that when the voltage is 0.8 V, after 60 min of adsorption, the residual phosphate concentration of the PEDOT / YMOF-NH2 electrode is 16.70 mg / L, while that of the YMOF-NH2 electrode is 19.38 mg / L; Figure 10 (c) shows that when the voltage is increased to 1.2 V, the residual phosphate concentrations are reduced to 14.12 mg / L (PEDOT / YMOF-NH2) and 16.67 mg / L (YMOF-NH2), respectively; Figure 10 (d) shows that when the voltage is set to 1.6 V, the adsorption effect reaches the peak, and the residual phosphate concentration is further reduced. The PEDOT / YMOF-NH2 electrode system is reduced to 10.00 mg / L, and the YMOF-NH2 electrode system is reduced to 14.71 mg / L.

[0109] Figure 10 (b) shows that when the voltage is -0.8 V, after 120 min of desorption, the phosphate concentrations in the eluents of the PEDOT / YMOF-NH2 and YMOF-NH2 electrodes are 11.22 mg / L and 11.59 mg / L, respectively; Figure 10 (c) shows that when the voltage is increased to -1.2 V, the phosphate concentrations in the eluents increase to 31.97 mg / L (PEDOT / YMOF-NH2) and 22.16 mg / L (YMOF-NH2), respectively; Figure 10 (d) shows that under the condition of -1.6 V, the desorption effect reaches the maximum, and the phosphate concentrations in the eluents are 76.82 mg / L (PEDOT / YMOF-NH2) and 58.92 mg / L (YMOF-NH2), respectively.

[0110] (4) Cyclic adsorption-desorption test:

[0111] To evaluate the cyclic regeneration ability of the PEDOT / YMOF-NH2 composite electrode, the mass of the PEDOT / YMOF-NH2 composite material in Step 2 of Example 1 was reduced from 0.06 g to 0.03 g; under the conditions of adsorption at 0.8 V and desorption at -1.6 V, five consecutive adsorption-desorption cycle tests were carried out; the adsorption capacity and desorption performance of the electrode after each cycle were recorded.

[0112] Figure 11 For Example 2, under different applied voltage conditions, the electro-assisted phosphate adsorption capacity of the PEDOT / YMOF-NH2 composite electrode supported by carbon felt and the change of the adsorption capacity during five cyclic adsorption and desorption processes were studied. (a) is a bar chart of the adsorption capacity under the condition of an applied voltage from 0 V to 1.6 V, and (b) is a graph of the change of the adsorption capacity during five cyclic adsorption and desorption processes.

[0113] Figure 12For Example 2, under different external electric field conditions, the change in the mass of phosphate adsorbed by the PEDOT / YMOF-NH2 composite electrode supported on carbon felt and the change in the adsorbed mass during five cycles of adsorption and desorption were studied. (a) is the column chart of the adsorption and desorption mass under the applied voltage condition from 0 V to 1.6 V, and (b) is the change chart of the adsorption and desorption mass during five cycles of adsorption and desorption.

[0114] Figure 11 (a) shows that as the applied positive electric field increases from 0 V to 1.6 V, the phosphate adsorption capacity of the PEDOT / YMOF-NH2 composite electrode increases from 130.42 mg P / g to 166.67 mg P / g, showing a significant enhancement. At the same time, Figure 12 (a) shows that the amount of captured phosphate increases from 7.82 mg to 10 mg, and the amount of desorbed phosphate increases from 0.20 mg to 3.84 mg. Excessive adsorption (greater than 7.82 mg) and weak phosphate release (less than 3.84 mg) may affect the cyclic regeneration ability of the electrode. Excessive adsorption may lead to the saturation of active sites on the electrode surface, thereby affecting the desorption efficiency; weak phosphate release may indicate that the desorption efficiency of the electrode material is limited to a certain extent, thus reducing the regeneration performance of the electrode.

[0115] Figure 11 (b) shows that in the first cycle, the adsorption capacity of the PEDOT / YMOF-NH2 composite electrode is about 120 mg P / g. After five consecutive adsorption-desorption cycles, the adsorption capacity decreases to 88.5 mg P / g, indicating that the adsorption ability of the electrode weakens during multiple cycles. In the fourth and fifth cycles, the electrode adsorbs 2.55 mg of phosphate and desorbs 2.56 mg of phosphate, indicating that the electrode reaches a dynamic balance of adsorption and desorption after five cycles and has good regeneration performance.

[0116] From the above tests, it can be seen that under the action of an applied positive electric field, the PEDOT / YMOF-NH2 composite electrode can significantly enhance the adsorption capacity for phosphate, and its adsorption performance is better than that of the YMOF-NH2 composite electrode; at the same time, under the condition of applying an appropriate negative voltage, the desorption performance of the electrode is also significantly improved. The cyclic test results further prove that the electrode has good regeneration stability during multiple adsorption-desorption processes. The above results fully verify the excellent performance of the PEDOT / YMOF-NH2 composite material for phosphate adsorption and enrichment and its application potential in water treatment and phosphorus resource recovery.

[0117] (5) The electro-assisted technology performance was comprehensively evaluated, focusing on key indicators such as the enrichment rate of phosphate, energy consumption, recovery efficiency, and concentration factor. The calculation formulas for each indicator are as follows:

[0118] Phosphate enrichment rate:

[0119] Energy consumption:

[0120] Phosphate recovery rate:

[0121] Concentration factor:

[0122] The performance indicators in the electric drive system include phosphate enrichment rate (R, unit: mmol / (m 2 ·h)), energy consumption (EC, unit: kWh / kgP), phosphate recovery rate (Pre, unit: %), and concentration factor (CF).

[0123] The amount of enriched phosphate is denoted as n p , with the unit of millimole (mmol). This value is affected by multiple factors, including the effective electrode area A (unit: m 2 ) and the total enrichment time t total (unit: h). These parameters determine the efficiency of the phosphorus enrichment process over time. The performance of the system is also affected by the applied voltage U (V) and current I (A). In addition, the total mass of enriched phosphate is denoted as m (kg). To evaluate the effectiveness of the system, two important phosphate concentration values are used: the initial phosphorus concentration C P,in (mg / L) in the feed and the final phosphorus concentration C P,eff (mg / L) in the effluent. The phosphorus concentration of phosphate in the concentrated product is denoted as C P,con (mg / L). These values are used to quantify the efficiency of the system in the phosphorus enrichment process.

[0124] ① Influence of voltage on phosphate enrichment rate:

[0125] Under the condition of positive electric field assistance, adsorption tests were carried out on the PEDOT / YMOF-NH2 composite electrode loaded on carbon felt by applying voltages of 0.8 V, 1.2 V, and 1.6 V respectively, and each test lasted for 60 min.

[0126] ② Energy consumption test:

[0127] a) Adsorption was carried out at a positive voltage of 0.8 V, and the energy consumption was recorded;

[0128] b) After the adsorption was completed at a positive voltage of 0.8 V, the process was switched to desorption, and desorption was carried out at a negative voltage of -1.6 V. A 0.01 M NaOH eluent was used for the desorption test, and the energy consumption was recorded.

[0129] ③ Phosphate recovery rate and concentration factor:

[0130] The phosphate recovery rate and concentration factor of the PEDOT / YMOF-NH2 composite electrode loaded on carbon felt and the YMOF-NH2 composite electrode loaded on carbon felt were tested under the applied voltages of 0 V, 0.8 V, 1.2 V, and 1.6 V, respectively.

[0131] Figure 13 For the comprehensive evaluation indexes of the PEDOT / YMOF-NH2 composite electrode loaded on carbon felt and the YMOF-NH2 composite electrode loaded on carbon felt in Example 2 and Comparative Experiment 2, (a) is the phosphate enrichment rate, (b) is the energy consumption, (c) is the phosphate recovery rate, and (d) is the concentration factor. As Figure 13 (a) shows, with the increase of the applied voltage, the phosphorus enrichment rate shows a gradually increasing trend. Especially at 1.6 V voltage, the phosphorus enrichment rate of the PEDOT / YMOF-NH2 electrode reaches 22.21 mmol / (m 2 ·h), which is significantly higher than the phosphorus enrichment rate range (6.36 to 17.0 mmol / (m 2 ·h)) of other typical CDI systems. As Figure 13 (b) shows, at 0.8 V voltage, the energy consumption in the adsorption stage is 0.15 kWh / kgP; while at -1.6 V voltage, the energy consumption in the desorption stage is 0.71 kWh / kgP, resulting in a total energy consumption of 0.86 kWh / kgP per cycle. This energy consumption is significantly lower than that of other typical capacitive deionization systems (usually 3.0 to 29.2 kWh / kgP), indicating that this system shows significant advantages in energy efficiency. Although higher voltages will lead to an increase in energy consumption, the overall energy consumption still remains at a low level, especially showing high efficiency under medium voltage conditions (0.8 V). As Figure 13 (c) shows, under all test conditions, the phosphate recovery rate of the PEDOT / YMOF-NH2 composite electrode is always higher than that of the pure YMOF-NH2 electrode. This result is attributed to the introduction of PEDOT, which improves the overall charge distribution of the electrode, thus more effectively promoting the capture of phosphate ions. As Figure 13 (d) shows, the PEDOT / YMOF-NH2 composite electrode shows a high concentration factor under various operating conditions, and its maximum value can reach 1.54, indicating its excellent ability in phosphorus concentration.

Claims

1. A preparation method of a capacitive deionization anode applied to phosphate adsorption and desorption, characterized in that It is carried out according to the following steps: I. Preparation of PEDOT / YMOF-NH2 composite material: ① Dissolve YCl3 in a mixed solution of deionized water and glacial acetic acid, then add 3,4-ethylenedioxythiophene liquid and mix by ultrasonic treatment to obtain Solution I; ② Dissolve 2-aminoterephthalic acid in deionized water, then add sodium hydroxide for a deprotonation reaction to obtain Solution II; ③ Mix Solution I and Solution II, and then react at room temperature for 10 h to 12 h to obtain Solution III; ④ Drop the ethanol solution of FeCl3 into Solution III, and react at room temperature with a stirring speed of 450 rpm to 600 rpm for 4 h to 8 h to obtain black crystals; ⑤ Wash and dry the black crystals to obtain the PEDOT / YMOF-NH2 composite material; II. Preparation of capacitive deionization anode: Disperse the PEDOT / YMOF-NH2 composite material, carbon black and polyvinylidene fluoride in ethanol, then stir to obtain a slurry. Uniformly coat the slurry on the surface of carbon felt, and finally dry to obtain a carbon felt-supported PEDOT / YMOF-NH2 composite electrode, thus completing the preparation method of the capacitive deionization anode applied to phosphate adsorption and desorption.

2. The preparation method of a capacitive deionization anode applied to phosphate adsorption and desorption according to claim 1, characterized in that In Step I①, the mass ratio of YCl3 to the volume of the mixed solution of deionized water and glacial acetic acid is 1 g:(15 - 18) mL; in the mixed solution of deionized water and glacial acetic acid in Step I①, the volume ratio of deionized water to glacial acetic acid is 1:(0.07 - 0.1); in Step I①, the mass ratio of YCl3 to 3,4-ethylenedioxythiophene liquid is 1:(2.0 - 2.3); the ultrasonic mixing in Step I① is specifically carried out under the condition of a power of 450 W to 600 W for 25 min to 30 min.

3. The preparation method of a capacitive deionization anode applied to phosphate adsorption and desorption according to claim 1, characterized in that In Step I②, the mass ratio of 2-aminoterephthalic acid to the volume of deionized water is 1 g:(38 - 40) mL; in Step I②, the mass ratio of 2-aminoterephthalic acid to sodium hydroxide is 1:(0.4 - 0.5); the deprotonation reaction in Step I② is specifically carried out at room temperature with a stirring speed of 450 rpm to 600 rpm for 25 min to 30 min.

4. The preparation method of a capacitive deionization anode applied to phosphate adsorption and desorption according to claim 1, characterized in that In Step I③, the volume ratio of Solution I to Solution II is 1:(2.3 - 2.5).

5. The preparation method of a capacitive deionization anode applied to phosphate adsorption and desorption according to claim 1, characterized in that In Step I④, the volume ratio of the ethanol solution of FeCl3 to Solution III is 1:(3.35 - 3.5); the concentration of the ethanol solution of FeCl3 in Step I④ is 0.5 mol / L to 1 mol / L.

6. The preparation method of a capacitive deionization anode applied to phosphate adsorption and desorption according to claim 1, characterized in that The washing and drying in Step I⑤ are specifically carried out according to the following steps: alternately use deionized water and anhydrous ethanol solution to wash repeatedly until the washing liquid is colorless, and then vacuum dry at a temperature of 60 °C to 70 °C for 10 h to 14 h.

7. The preparation method of a capacitive deionization anode applied to phosphate adsorption and desorption according to claim 1, characterized in that In Step 2, the mass ratio of the PEDOT / YMOF-NH2 composite material to carbon black is (8 - 8.5):1; in Step 2, the mass ratio of the carbon black to polyvinylidene fluoride is 1:(1 - 1.5); in Step 2, the mass-to-volume ratio of the PEDOT / YMOF-NH2 composite material to ethanol is 1 g:(400 - 500) mL; the coating thickness of the slurry in Step 2 is 0.02 mm - 0.05 mm; the drying in Step 2 is specifically carried out under the conditions of a temperature of 60°C - 70°C and vacuum drying for 10 h - 14 h.

8. The application of a capacitive deionization anode for phosphate adsorption and desorption prepared as claimed in claim 1, characterized in that It is used for the adsorption and desorption of phosphate in phosphate-containing water bodies.

9. The application of a capacitive deionization anode for phosphate adsorption and desorption according to claim 8, characterized in that The adsorption and desorption of phosphate in the phosphate-containing water body are specifically carried out according to the following steps: I. Using the carbon felt-supported PEDOT / YMOF-NH2 composite electrode as the capacitive deionization anode and the carbon felt-supported carboxylated activated carbon electrode as the capacitive deionization cathode, assemble the sealing plate, capacitive deionization anode, anion exchange membrane, gasket, capacitive deionization cathode, and sealing plate in sequence from one side to the other side. Control the distance between the anion exchange membrane and the capacitive deionization cathode to be 2 mm - 5 mm through the gasket. Set the water inlet on the sealing plate on the side of the capacitive deionization anode and the water outlet on the sealing plate on the side of the capacitive deionization cathode to obtain a capacitive deionization device. II. Connect the capacitive deionization anode and the capacitive deionization cathode to the positive and negative poles of the power supply respectively. Use the phosphate-containing water body as the water to be treated. Pass the water to be treated into the capacitive deionization device from the water inlet and circulate it. Adsorb under the conditions of an applied voltage of 0.8 V - 1.6 V and an effluent flow rate of 12 mL / min - 15 mL / min. The concentration of phosphate in the phosphate-containing water body is 10 mg / L - 500 mg / L, and the pH value is 6 to 10. III. Connect the capacitive deionization anode and the capacitive deionization cathode to the negative and positive poles of the power supply respectively to reverse the electrode polarity. Use a sodium hydroxide solution with a concentration of 0.01 mol / L - 0.02 mol / L as the eluent. Pass the eluent into the capacitive deionization device from the water inlet and circulate it. Desorb for 0.5 h - 2 h under the conditions of an applied voltage of -0.8 V - -1.6 V and an effluent flow rate of 12 mL / min - 15 mL / min.

10. The application of a capacitive deionization anode for phosphate adsorption and desorption according to claim 9, characterized in that The carbon felt-supported carboxylated activated carbon electrode described in Step I is specifically prepared according to the following steps: ①Disperse activated carbon in deionized water, stir for 20 min to 30 min at room temperature with a stirring speed of 450 rpm to 600 rpm, then filter, repeat dispersion and filtration until the conductivity of the filtrate is lower than 10 μS / cm, and then vacuum dry for 6 h to 12 h at a temperature of 60 °C to 70 °C to obtain pretreated activated carbon. Add nitric acid solution to the pretreated activated carbon, stir and heat at a temperature of 60 °C to 80 °C and a stirring speed of 450 rpm to 600 rpm for 65 h to 70 h, filter after the reaction, and wash repeatedly with deionized water until the washing liquid is neutral. Finally, vacuum dry for 5 h to 10 h at a temperature of 60 °C to 70 °C to obtain carboxylated activated carbon; the concentration of the nitric acid solution is 7.6 mol / L to 8 mol / L; the mass ratio of the pretreated activated carbon to the volume of the nitric acid solution is 1 g:(8 - 10) mL; ②Disperse carboxylated activated carbon, carbon black and polyvinylidene fluoride in ethanol, then stir to obtain a slurry. Coat the slurry evenly on the surface of carbon felt according to a coating thickness of 0.02 mm to 0.05 mm, and finally vacuum dry for 5 h to 12 h at a temperature of 65 °C to 80 °C to obtain a carbon felt-supported carboxylated activated carbon electrode; the mass ratio of the carboxylated activated carbon to the carbon black is (8 - 8.5):1; the mass ratio of the carbon black to the polyvinylidene fluoride is 1:(1 - 1.5); the mass ratio of the carboxylated activated carbon to the volume of ethanol is 1 g:(66 - 70) mL.

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