W 18 O 49 @Carbon aerogels and methods for their preparation, electrode sheets and uses thereof

Abstract

The present application belongs to the technical field of composite materials, and particularly relates to a W 18 O 49 @carbon aerogel and a preparation method thereof, and an electrode sheet prepared from the W 18 O 49 @carbon aerogel and an application of the electrode sheet in removing lead ions in wastewater through electric adsorption. 18 O 49 @carbon aerogel, which comprises the following steps: (1) preparation of the W 18 O 49 @carbon aerogel. The present application has the advantages that: W 18 O 49 @carbon aerogel electrode preparation method is simple, low in cost, free of secondary pollution to the environment, and W 18 O 49 @carbon aerogel electrode has high adsorption efficiency for lead ions in water and can be continuously recycled. The method not only improves the hydrophilicity of the carbon aerogel prepared at normal temperature and pressure, but also utilizes the W 18 O 49 large specific surface area to improve the defect of the carbon material that the adsorption sites for heavy metal ions are few, so as to improve the removal efficiency of the carbon material in removing heavy metal ions in wastewater through electric adsorption.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of water treatment, and particularly relates to a W 18 O 49 @ carbon aerogel and a preparation method thereof, and an electrode sheet prepared from the W 18 O 49 @ carbon aerogel, and application of the electrode sheet in removing lead ions in wastewater by electro-adsorption, wherein the electrode sheet is applied to electrochemical adsorption and has low energy consumption, high efficiency, easy regeneration of electrode material, no secondary pollution, easy operation and easy control. BACKGROUND

[0002] Heavy metals are not only highly toxic, but also have the property of accumulation, and exposure to water and air media is one of the main pollutants causing soil, water and air pollution. Heavy metal pollution mainly enters the human body through respiration and food intake, and causes serious harm to human organs, nervous system and respiratory system due to non-metabolism, so the treatment of heavy metal pollution is urgent.

[0003] Currently, the methods for removing heavy metal pollution in wastewater mainly include electrodialysis, ion exchange, chemical precipitation, membrane filtration and electrochemical adsorption. Among the above methods, adsorption is reported as the most popular method due to higher efficiency and application feasibility. Conventional adsorption has inherent limitations such as generation of a large amount of sludge, low efficiency, critical operating conditions and expensive treatment, and no secondary pollution; common commercial adsorption materials include zeolite, silica gel and artificially synthesized polymers. The removal effect of these commercial materials is good, but the reusability is poor, the adsorption stability is also poor, and the conductivity is weak, which is not conducive to the removal of heavy metal ions under the coordination of an electric field. Recently, nanomaterials and carbon nanotubes (CNT) have attracted much attention for the removal of heavy metals in water and wastewater. Due to the pore size and pore volume, they have a larger adsorption capacity. However, most of the commercial and carbon nanotube-based adsorption materials are expensive, so they are not conducive to wide application in industrial removal of heavy metal ions in water treatment. Electrochemical adsorption is an adsorption phenomenon caused by current or polarization potential on the surface of a charged electrode. Compared with traditional electro-adsorption, electrochemical adsorption not only occurs physical adsorption, but also chemical adsorption, and an oxidation-reduction reaction occurs in the adsorption process. The working voltage is generally not more than 1.2V, the energy consumption is less, the electrode can be regenerated after electrode reversal or short circuit, the operation is simple, and there is no secondary pollution, so it is a promising method for treating pollutants at present. SUMMARY

[0004] One of the purposes of the present application is to provide a preparation method of a W 18 O 49 @ carbon aerogel, and a W 18 O 49The carbon aerogel is used as an electrode material to remove lead ions in waste water by electrochemical adsorption, and the removal rate is about 88%, the carbon aerogel has low energy consumption, high treatment efficiency, and the electrode material removal effect is maintained after regeneration, and the carbon aerogel has no secondary pollution, is easy to operate and control, and the like.

[0005] To achieve the above object, the application adopts the following technical scheme: a W 18 O 49 @The preparation method of the carbon aerogel comprises the following steps:

[0006] S1, preparation of the carbon aerogel: resorcinol and sodium carbonate with a molar ratio of (500-1000): 1 are dissolved in water, then formaldehyde aqueous solution is added, and the mixture is fully stirred at room temperature to obtain a mixed solution, the molar ratio of resorcinol to formaldehyde in the formaldehyde aqueous solution in the mixed solution is 1:2, and the solid-liquid mass ratio of the mixed solution is 3:7;

[0007] The mixed solution is placed in 60-100 DEG C for 3-4 h, and then placed in 50-60 DEG C for 24 h, then acetone is added for soaking to replace water, and a brown resorcinol-formaldehyde organic gel is obtained, the resorcinol-formaldehyde organic gel is ground, then calcined at 650-700 DEG C under nitrogen protection for 2-3 h, and a black resorcinol-formaldehyde carbon aerogel is obtained;

[0008] S2, preparation of the W 18 O 49 @The carbon aerogel is prepared: the tungsten chloride is dissolved in ethanol to obtain a yellow solution, then the prepared resorcinol-formaldehyde carbon aerogel is added for ultrasonic dispersion to obtain a mixed dispersion, the mass ratio of the resorcinol-formaldehyde carbon aerogel to the tungsten chloride in the ultrasonic dispersion in ethanol is (1-5): 1, the mixed dispersion is transferred to a high-pressure reaction kettle, and heated at 160-180 DEG C for 14-16 h; after natural cooling, the precipitate is separated, washed with ethanol and water, and vacuum dried to obtain the W 18 O 49 The composite material loaded on the carbon aerogel is abbreviated as W 18 O 49 @The carbon aerogel.

[0009] The W 18 O 49 @The preparation method of the carbon aerogel is further improved:

[0010] Preferably, the solubility of the formaldehyde aqueous solution in step S1 is 37wt%-40wt%.

[0011] Preferably, the heating rate of the resorcinol-formaldehyde organic gel during calcination in step S1 is 2-5 DEG C / min.

[0012] Preferably, the acetone is replaced every 5-15 hours in step S1, and the soaking is continued for 2-3 days at room temperature.

[0013] Preferably, the precipitate is washed with ethanol and water and then dried at 60-80°C under vacuum in step S2.

[0014] The second object of the present application is to provide a W 18 O 49 @ aerogel prepared by any of the above preparation methods.

[0015] The third object of the present application is to provide an electrode sheet prepared from the above W 18 O 49 @ aerogel, and the preparation method is as follows: graphite plates are pretreated with ethanol, dried and cooled to serve as a current collector, W 18 O 49 @ aerogel, polytetrafluoroethylene binder (PTFE binder) and conductive carbon black are mixed and uniformly ground, and then applied to the graphite plates at a coating amount of 0.003-0.01 g / cm 2 , dried at a constant temperature and cooled to obtain the electrode sheet.

[0016] The fourth object of the present application is to provide the use of the above electrode sheet in removing heavy metals from wastewater, wherein the electrode sheet is used as a cathode, the graphite plate is used as an anode, and the electrode sheet and the graphite plate are assembled and installed in an electrolytic cell, wastewater is added to the electrolytic cell, the pH of the wastewater is adjusted to 2-7, the initial concentration of heavy metals is 20-200 mg / L, a voltage of 0-1.2 V is applied, and the heavy metal ions in the wastewater are removed by electrosorption.

[0017] The use of the electrode sheet in removing heavy metals from wastewater is further improved as follows:

[0018] Preferably, the pH of the wastewater is adjusted to 5, the initial concentration of heavy metals is 100 mg / L, and a voltage of 1.2 V is applied.

[0019] Preferably, when the electrode sheet is saturated, it is removed and placed in a 1 mol / L hydrochloric acid solution to perform desorption under a reversed voltage.

[0020] The present application has the following advantages over the prior art:

[0021] 1) The present application provides a W 18 O 49Preparation method of carbon aerogel. Carbon aerogel is one of the popular electrode materials for supercapacitors due to its large specific surface area and three-dimensional interpenetrating pore network structure. Carbon aerogel is formed by the gradual growth and aggregation of monomer clusters generated by sol-gel reaction, and then the aerogel is dried, and finally the organic aerogel is pyrolyzed at high temperature. However, supercritical drying is to control the temperature and pressure to make the solvent change from a fluid state to a supercritical state, which makes the drying process extremely dangerous and expensive. The present application uses resorcinol and formaldehyde solution to undergo dehydration polymerization condensation under the catalysis of sodium carbonate, and then uses the low boiling point and easy volatilization characteristics of acetone to replace the water solvent in the aerogel at room temperature and atmospheric pressure to achieve the purpose of drying. Therefore, the present application replaces supercritical drying with environmental condition drying to save cost and reduce danger.

[0022] 2) The W 18 O 49 @ Carbon aerogel as electrode material utilizes electrochemical adsorption to remove lead ions in wastewater, with a removal rate of about 88%, low energy consumption, high treatment efficiency, electrode material removal effect remains regenerated, no secondary pollution, easy operation, easy control, etc.

[0023] 3) The W 18 O 49 @ Carbon aerogel as electrode material utilizes electrochemical adsorption to remove lead ions in wastewater, with a removal rate of about 88%, low energy consumption, high treatment efficiency, electrode material removal effect remains regenerated, no secondary pollution, easy operation, easy control, etc. 18 O 49 Carbon aerogel as electrode material utilizes electrochemical adsorption to remove lead ions in wastewater, with a removal rate of about 88%, low energy consumption, high treatment efficiency, electrode material removal effect remains regenerated, no secondary pollution, easy operation, easy control, etc. 18 O 49 Carbon aerogel as electrode material utilizes electrochemical adsorption to remove lead ions in wastewater, with a removal rate of about 88%, low energy consumption, high treatment efficiency, electrode material removal effect remains regenerated, no secondary pollution, easy operation, easy control, etc. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is the XRD pattern of the W 18 O 49 @ Carbon aerogel prepared in Example 1;

[0025] Figure 2 is the XRD pattern of the W 18 O 49 and W 18 O 49 @ Carbon aerogel prepared in Example 1;

[0026] Figure 3CW31 electrode sheet of Example 1, CW11 electrode sheet prepared in Example 2, CW51 electrode sheet prepared in Example 3, Comparative electrode C700 electrode sheet, Comparative electrode W 18 O 49 A graph of the relationship between the saturated adsorption amount of lead ions and the electrode sheet;

[0027] Figure 4 A graph of the relationship between the saturated adsorption amount of lead ions and the pH in the CW31 electrode sheet of Example 1;

[0028] Figure 5 A graph of the relationship between the saturated adsorption amount of lead ions and the initial concentration of lead ions in the CW31 electrode sheet of Example 1;

[0029] Figure 6 A graph of the relationship between the saturated adsorption amount of lead ions and the current application time in the CW31 electrode sheet of Example 1;

[0030] Figure 7 A graph of the relationship between the saturated adsorption amount of lead ions and the voltage in the CW31 electrode sheet of Example 1;

[0031] Figure 8 A graph of the relationship between the saturated adsorption amount of lead ions and the coexisting ion competition in the CW31 electrode sheet of Example 1;

[0032] Figure 9 A graph of the relationship between the removal rate of lead ions and the cycle number in the CW31 electrode sheet of Example 1. DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in combination with examples. All other examples obtained by those skilled in the art based on the examples in the present application without any creative labor fall within the scope of protection of the present application.

[0034] Example 1

[0035] This example provides a method for preparing a W 18 O 49 The method for preparing the carbon aerogel composite material and the electrode sheet is as follows:

[0036] S1, Preparation of carbon aerogel: using sol-gel method, 11.0195 g of resorcinol (i.e. 0.1 mol) and 0.0212 g of Na2CO3 (i.e. 0.0002 mol) were dissolved in 30 mL of water, then stirred uniformly, 16.2455 g of formaldehyde aqueous solution with a concentration of 37 wt% was added to the above solution, and the mixed solution was stirred for 30 min to obtain a mixed solution, the molar ratio of resorcinol and sodium carbonate, formaldehyde in the solution in the mixed solution was 0.1:0.0002:0.2, and the solid-liquid mass ratio of the mixed solution was 3:7;

[0037] The mixed solution was placed in an 80°C oven for 4 h, then placed in a 50°C oven for 24 h, then soaked with acetone to replace the water, and placed at room temperature for 48 h (acetone was replaced every 10 h during this period), to obtain a brown resorcinol-formaldehyde organic gel (RF). The RF was ground and loaded into a quartz boat, and calcined at 700°C (5°C / min) under nitrogen in a tube furnace for 2 h to obtain black resorcinol-formaldehyde carbon aerogel (C700).

[0038] S2, Preparation of W 18 O 49 @carbon aerogel: 0.22 g of tungsten chloride was dissolved in 30 mL of ethanol and ultrasonically dispersed for 20 min to obtain a yellow solution, then 0.66 g of resorcinol-formaldehyde carbon aerogel (C700) was added and ultrasonically dispersed for 30 min to obtain a mixed dispersion, the mixed dispersion was transferred to a 50 mL high-pressure reaction kettle, and heated at 180°C for 16 h; after natural cooling, the precipitate was separated by centrifugation at a speed of 10000 r / min, washed with ethanol and water for 3 times respectively, and then vacuum dried at 60°C for 4 h to obtain W 18 O 49 @carbon aerogel composite material, denoted as CW31.

[0039] S3, Preparation of electrode sheet: graphite plate was pretreated with ethanol, and after drying and cooling, it was used as a current collector, W 18 O 49 @carbon aerogel, polytetrafluoroethylene binder (PTFE binder), and conductive carbon black were mixed and ground uniformly, and then applied on a 3 cm x 5 cm graphite plate, with an application amount of 0.006 g / cm 2 , and after constant temperature drying and cooling, a CW31 electrode sheet was obtained.

[0040] Example 2

[0041] The present embodiment provides a method for preparing W 18 O 49 @carbon aerogel composite material, the specific steps refer to example 1, and the difference is that 0.22 g of resorcinol-formaldehyde carbon aerogel is added in step S2, and finally W18 O 49 @Carbon aerogel composite material, recorded as CW11. And CW11 electrode sheet is prepared.

[0042] Example 3

[0043] This embodiment provides a method for preparing W 18 O 49 @Carbon aerogel composite material, the specific steps refer to example 1, the difference is that 1.10g of resorcinol-formaldehyde carbon aerogel is added in step S2, and finally W 18 O 49 @Carbon aerogel composite material, recorded as CW51. And CW51 electrode sheet is prepared.

[0044] Figure 1 is the W 18 O 49 @Carbon aerogel prepared in example 1; Figure 2 is the W 18 O 49 and W 18 O 49 @Carbon aerogel prepared in example 1; SEM images of Figure 1 It can be seen that the morphology of single W 18 O 49 is urchin-like, and after being loaded on the surface of carbon aerogel, urchin-like W 18 O 49 is also grown on it, which indicates that the W 18 O 49 @Carbon aerogel composite material is successfully synthesized.

[0045] Preparation of control electrode sheet 1: pretreat the graphite plate with ethanol, and after drying and cooling, use it as the current collector. Take resorcinol-formaldehyde carbon aerogel (C700), polytetrafluoroethylene binder (PTFE binder) and conductive carbon black with a mass ratio of 8:1:1, the mass of resorcinol-formaldehyde carbon aerogel (C700) is 0.006g / cm 2 , mix and grind uniformly, apply on the graphite plate, the application amount is 0.006g / cm 2 , after constant temperature drying and cooling, C700 electrode sheet is prepared.

[0046] Preparation of control electrode sheet 2: pretreat the graphite plate with ethanol, and after drying and cooling, use it as the current collector. Take W 18 O 49 , polytetrafluoroethylene binder (PTFE binder) and conductive carbon black with a mass ratio of 8:1:1, the mass of W 18 O 49 is 0.072g, mix and grind uniformly, apply on the graphite plate, the application amount is 0.006g / cm2 , constant temperature drying and cooling, to obtain W 18 O 49 electrode sheet.

[0047] The control electrode sheet 1, the control electrode sheet 2, the CW31 electrode sheet prepared in Example 1, the CW11 electrode sheet prepared in Example 2, and the CW51 electrode sheet prepared in Example 3 were respectively used as adsorbent electrode to carry out static batch electro-adsorption experiment on lead-containing wastewater. The lead-containing wastewater was 80 mL, the pH was 5, the lead ion concentration was 100 mg / L, the power-on time was 150 min, the voltage was 1.2 V, and the mass of the five adsorbents on the electrode sheet was 0.072 g. The adsorption bar chart under different adsorbent types is shown in Figure 3 . It can be seen from Figure 3 that the CW31 has the best adsorption effect, and the saturated adsorption capacity of the CW31 composite material for lead is 130.63 ± 3.5 mg / g.

[0048] The W 18 O 49 @ carbon aerogel composite material CW31 prepared in Example 1 was used as adsorbent to carry out static batch electro-adsorption experiment on lead-containing wastewater. The mass of the W 18 O 49 @ carbon aerogel composite material on the electrode sheet was 0.072 g, the lead-containing wastewater was 80 mL, the lead ion concentration was 100 mg / L, the power-on time was 150 min, the voltage was 1.2 V, and the pH was adjusted to 2, 3, 4, 5, and 6 in turn by using 0.1 mol / L hydrochloric acid and 0.1 mol / L sodium hydroxide solution. The adsorption bar chart under different pH conditions is shown in Figure 4 . It can be seen from Figure 4 that the adsorption effect is the best when the pH is 5.

[0049] The W 18 O 49 @ carbon aerogel composite material CW31 prepared in Example 1 was used as adsorbent to carry out static batch electro-adsorption experiment on lead-containing wastewater. The mass of the W 18 O 49 @ carbon aerogel composite material CW31 on the electrode sheet was 0.072 g, the lead-containing wastewater was 80 mL, the pH was 5, and the concentration of Pb 2+ was 20 mg / L, 50 mg / L, 100 mg / L, 150 mg / L, and 200 mg / L in turn, the power-on time was 150 min, and the voltage was 1.2 V. The adsorption bar chart under different concentrations of Pb 2+ is shown in Figure 5 . Figure 5 The results show that the lead ion concentration of 100 mg / L is the best in terms of removal rate and adsorption effect, the removal rate is 80.18% ± 2.7%, and the saturated adsorption capacity of lead is 130.63 ± 3.5 mg / g.

[0050] W 18 O 49 @The carbon aerogel composite material CW31 was used as adsorbent to carry out static batch electro-adsorption experiment on lead-containing wastewater. The W 18 O 49 @The mass of the carbon aerogel composite material CW31 was 0.072 g, the pH of the lead-containing wastewater was 5, the concentration of Pb 2+ was 100 mg / L, the power-on time was 150 min, and the voltage was 1.2 V. The samples were taken at 0, 2, 5, 10, 30, 60, 90 and 150 min, and the adsorption capacity was tested. The results are shown in Table 1. Figure 6 Figure 6 It can be seen from Table 1 that the adsorption tended to be balanced after 30 min of power-on, and the saturated adsorption capacity was 1401.45 mg / g after 150 min.

[0051] The C700 electrode sheet of the control electrode sheet 1 and the CW31 electrode sheet prepared in Example 1 were used as adsorption electrodes to carry out static batch electro-adsorption experiment on lead-containing wastewater. The resorcinol-formaldehyde carbon aerogel (C700) and the W 18 O 49 @The mass of the carbon aerogel composite material CW31 was 0.072 g, the pH of the lead-containing wastewater was 5, the concentration of Pb 2+ was 100 mg / L, the power-on time was 150 min, and the voltage was 0.0 V, 0.4 V, 0.8 V, 1.2 V and 1.6 V respectively. The adsorption capacity under different voltages was tested. The results are shown in Table 2. Figure 7 Figure 7 It can be seen from Table 2 that the adsorption effect of the CW31 electrode sheet was better than that of the unmodified C700, and the adsorption capacity increased with the increase of the voltage, but the trend of the influence on the CW31 was greater.

[0052] The W 18 O 49 @The carbon aerogel composite material CW31 was used as adsorbent to carry out static batch electro-adsorption experiment on lead-containing wastewater. The W 18 O 49 @The mass of the carbon aerogel composite material was 0.072 g, the power-on time was 150 min, the voltage was 1.2 V, and the pH was 5; 80 mL of lead-containing wastewater was divided into 5 parts, and the heavy metal ion content in the 5 parts of lead-containing wastewater was as follows: the concentration of lead ions was 50 mg / L, Pb 2+ / Cu 2+ was 50 mg / L each, Pb 2+ / Cd 2+ was 50 mg / L each, and Pb 2+ / Zn 2+ ​​Two kinds of 50mg / L each, and mixed Pb 2+ / Cu 2+ / Cd 2+ / Zn 2+ Four kinds of 50mg / L each were tested for Pb under different heavy metal conditions. 2+ Adsorption amount, the results are as follows Figure 8 As shown. Figure 8 It can be seen that the ability to remove Pb(II) decreases when Zn(II), Cu(II) or Cd(II) competes in the Pb(II) solution compared to Pb(II) alone. Therefore, the order of decreasing competitiveness is Cu(II) > Zn(II) > Cd(II).

[0053] The W prepared in Example 1 18 O 49 @ Using carbon aerogel composite material CW31 as an adsorbent, a static batch electrosorption experiment was conducted on lead-containing wastewater. The lead-containing wastewater was 80mL, pH=5, lead ion concentration was 100mg / L, the power-on time was 150min, the voltage was 1.2V, and the mass of the adsorbent on the electrode was 0.072g; after adsorption saturation, desorption was carried out with 1mol / L hydrochloric acid, and the voltage was reversed (desorption voltage was 1.2V, power-on for 60min). After rinsing the electrode with deionized water until neutral, the second adsorption was carried out according to the above conditions, and the removal rate dropped from 88.83% to 85.14%. After adsorption saturation, the second desorption was carried out, and the second adsorption was carried out according to the above conditions. Other conditions remained unchanged, and the removal rate was measured to be 86.77%. After adsorption saturation, the third desorption was carried out, and the third adsorption was carried out according to the above conditions. Other conditions remained unchanged, and the removal rate was measured to be 87.39%. The adsorption effect of cyclic adsorption-desorption is shown as follows. Figure 9 It can be seen that after three times of adsorption and desorption, the removal rate of the adsorbent remains basically unchanged, indicating that the adsorption performance is stable and can be recycled.

[0054] Those skilled in the art will appreciate that the foregoing descriptions are merely specific embodiments of the present invention, and not exhaustive. It should be noted that numerous variations and modifications are possible for those skilled in the art, and all such variations and modifications that do not exceed the scope of the claims should be considered within the scope of protection of the present invention.

Claims

1. A W 18 O 49 @method for producing a carbon aerogel, characterized by, Comprising the following steps: S1, preparation of carbon aerogel: resorcinol and sodium carbonate with a molar ratio of (500-1000):1 are dissolved in water, then a formaldehyde aqueous solution with a solubility of 37wt%-40wt% is added, and the mixed solution is obtained by fully stirring at room temperature, wherein the molar ratio of resorcinol to formaldehyde in the formaldehyde aqueous solution in the mixed solution is 1:2, and the solid-liquid mass ratio of the mixed solution is 3:7; The mixed solution is placed in 60-100℃ for 3-4h, and then placed in 50-60℃ for 24h, then acetone is added to replace water, and a brown resorcinol-formaldehyde organic gel is obtained, the resorcinol-formaldehyde organic gel is ground, then calcined at 650-700℃ under nitrogen protection for 2-3h, and a black resorcinol-formaldehyde carbon aerogel is obtained; S2, W 18 O 49 @Carbon aerogel preparation: dissolve tungsten chloride in ethanol to obtain a yellow solution, then add the above prepared resorcinol-formaldehyde carbon aerogel to continue ultrasonic dispersion to obtain a mixed dispersion solution, the mass ratio of the resorcinol-formaldehyde carbon aerogel and tungsten chloride ultrasonically dispersed in ethanol is (1-5): 1, transfer the mixed dispersion solution to a high-pressure reaction kettle, heat and react at 160-180℃ for 14-16h; after natural cooling, separate the precipitate, wash with ethanol and water, and vacuum dry to obtain W 18 O 49 Composite material loaded on carbon aerogel, abbreviated as W 18 O 49 @Carbon aerogel.

2. The W 18 O 49 @Method for preparing carbon aerogel, characterized in that, The heating rate of the resorcinol-formaldehyde organic gel in step S1 during calcination is 2-5℃ / min.

3. The W of claim 1, wherein the W is a W 18 O 49 @The method for preparing carbon aerogel is characterized in that, In step S1, the acetone is replaced every 5-15h when replacing water with acetone, and the continuous placement is carried out at room temperature for 2-3 days.

4. The W of claim 1, wherein the W is a W 18 O 49 @The method for preparing carbon aerogel is characterized in that, The precipitate in step S2 is washed with ethanol and water, and then vacuum dried at 60-80℃.

5. A W prepared by the process of any one of claims 1 to 4. 18 O 49 @carbon aerogel.

6. An electrode sheet made of the W 18 O 49 @carbon aerogel according to any one of the preceding claims, characterized in that The preparation method is as follows: pretreat the graphite plate with ethanol, dry and cool to serve as the current collector, weigh W 18 O 49 @Carbon aerogel, polytetrafluoroethylene binder (PTFE binder), and conductive carbon black are mixed and uniformly ground, and then applied on the graphite plate at a coating amount of 0.003-0.01 g / cm 2 After constant temperature drying and cooling, the electrode sheet is obtained.

7. Use of the electrode sheet according to claim 6 for removing heavy metals from wastewater, characterized in that, The electrode sheet is assembled and installed in the electrolytic cell as a cathode, and a graphite plate is assembled and installed as an anode, wastewater is added to the electrolytic cell, the pH of the wastewater is adjusted to 2-7, the initial concentration of heavy metals is 20-200mg / L, a voltage of 0V-1.2V is applied, and the heavy metal ions in the wastewater are removed by electrosorption.

8. Use of the electrode sheet according to claim 7 for removing heavy metals from wastewater, characterized in that, The pH of the wastewater is adjusted to 5, the initial concentration of heavy metals is 100mg / L, and a voltage of 1.2V is applied.

9. Use of the electrode sheet according to claim 7 for removing heavy metals from wastewater, characterized in that, When the electrode sheet is saturated, it is taken out and placed in a 1mol / L hydrochloric acid solution, and the voltage is reversed for desorption.

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