Double-path heavy metal fixing and removing method based on photoelectrochemical process driving

Abstract

The invention relates to the technical field of environmental pollution treatment, in particular to a double-path heavy metal fixing and removing method based on photoelectrochemical process driving. By designing an innovative photoelectrochemical system, and combining a titanium dioxide photo-anode rich in oxygen vacancies and a frame material with an ion confinement structure as a cathode, efficient selective adsorption and fixation of heavy metal ions are realized. Under the illumination condition, the system fixedly removes the heavy metal ions at the anode through an oxidation path, and meanwhile, the system fixedly removes the heavy metal ions at the cathode through an ion embedding path, so that the fixed removal efficiency of the heavy metal is remarkably improved. The method not only improves the removal efficiency of heavy metal ions, but also reduces environmental pollution through resource recovery, has the advantages of simplicity and convenience in operation, low cost, easiness in large-scale application and the like, and provides a novel and environment-friendly solution for heavy metal pollution treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental pollution control, and in particular to a dual-path heavy metal fixation and removal method driven by a photoelectrochemical process. Background Art

[0002] With the rapid development of industrialization and urbanization, various pollutants released by human activities are increasing, especially heavy metal pollution, which poses an increasingly serious threat to the environment and human health. For example, lead (Pb), as a common heavy metal pollutant, is widely present in batteries, pigments, coatings, chemicals and electronic waste. Heavy metals are highly toxic and persistent, and can exist in water environments and soils for a long time, and accumulate through the food chain, causing great harm to ecosystems and human health. Therefore, how to efficiently and sustainably remove heavy metal pollution has become an urgent problem to be solved.

[0003] Traditional methods for heavy metal pollution control mainly include chemical precipitation, ion exchange, adsorption, electrochemical and bioremediation. Although these methods can remove heavy metal ions to a certain extent, they often have problems such as low treatment efficiency, complex operation, high cost and secondary pollution, which are difficult to meet the needs of practical applications. For example, chemical precipitation is prone to produce a large amount of precipitate, which requires further treatment; ion exchange and adsorption methods are inefficient and difficult to regenerate; electrochemical methods have high energy consumption; bioremediation methods have shortcomings such as long treatment time and limited scope of application. In recent years, photoelectrochemical technology has gradually become a hot topic in heavy metal pollution control research due to its high efficiency and environmental protection. Photoelectrochemical technology achieves efficient degradation and removal of pollutants through the synergistic effect of light energy and electrical energy. However, the existing photoelectrochemical methods mainly focus on the degradation of pollutants, and there is little research on the fixation and removal of heavy metal ions. In addition, a single photoelectrochemical process is difficult to simultaneously meet the needs of efficient fixation and removal of heavy metal ions.

[0004] Therefore, there is an urgent need to develop more efficient and sustainable methods for controlling heavy metal pollution. Summary of the invention

[0005] In order to solve the above problems, the purpose of the present invention is to provide a dual-path heavy metal fixation and removal method driven by a photoelectrochemical process. In the present invention, photogenerated electrons and holes generated by the photoanode under light are used, wherein the holes participate in the oxidation reaction of the anode, react with the heavy metal ions in the water, oxidize them and convert them into insoluble or low-solubility heavy metal compounds fixed on the surface of the photoanode; at the same time, the photogenerated electrons are transmitted to the cathode through an external circuit, and the cathode uses its ion confinement structure to selectively adsorb and embed heavy metal ions to achieve the fixation of heavy metals.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] The present invention provides a dual-path heavy metal fixation and removal method driven by a photoelectrochemical process, comprising the following steps:

[0008] A titanium dioxide electrode with oxygen-rich vacancies is used as a photoanode, and a copper-based Prussian blue framework material electrode with an ion-confined structure is used as a cathode. Heavy metal wastewater is used as the electrolyte. Photoelectrochemical reactions are carried out under light, and heavy metal ions are fixed on the surface of the photoanode and cathode to achieve the removal of heavy metals in heavy metal wastewater.

[0009] In one embodiment of the present invention, during the photoelectrochemical reaction, the separation efficiency of photogenerated electrons and holes is optimized by the transmission efficiency of photogenerated electrons, and the reaction time is 1 to 60 minutes.

[0010] In one embodiment of the present invention, the titanium dioxide having oxygen-rich vacancies is prepared by the following method:

[0011] (A1) mixing deionized water, concentrated hydrochloric acid and tetrabutyl titanate to obtain a mixed solution;

[0012] (A2) placing the conductive surface of the pretreated FTO downward on the upper surface of the mixed solution obtained in step (A1), baking and performing post-treatment to obtain FTO grown with TiO2;

[0013] (A3) immersing the FTO grown with TiO2 in a mixed solution of concentrated hydrochloric acid and titanium tetrachloride, and performing post-treatment after baking to obtain an electrode precursor;

[0014] (A4) The electrode precursor is calcined to obtain a titanium dioxide electrode rich in oxygen vacancies.

[0015] In one embodiment of the present invention, in step (A1), the volume ratio of deionized water, concentrated hydrochloric acid and tetrabutyl titanate is 10-50:2-5:1.

[0016] In one embodiment of the present invention, in step (A2), during the baking process, the temperature is 150-200° C. and the time is 3-6 hours.

[0017] In one embodiment of the present invention, in step (A2), the pretreated FTO is prepared by the following method:

[0018] The fluorine-doped tin oxide conductive glass (FTO) was ultrasonically cleaned with deionized water for 10 to 15 minutes, repeated 1 to 3 times, and then ultrasonically cleaned with ethanol for 10 to 15 minutes, repeated 1 to 3 times, and placed in a 60° C. to 100° C. oven for drying.

[0019] In one embodiment of the present invention, in step (A2), the post-treatment is specifically as follows:

[0020] After cooling to room temperature, take it out and ultrasonically clean it with ethanol for 10 to 15 minutes, repeat 1 to 3 times, and put it in an oven at 60°C to 100°C to dry it.

[0021] In one embodiment of the present invention, in step (A3), during the baking process, the temperature is 75-100° C. and the time is 1-2 hours.

[0022] In one embodiment of the present invention, in step (A3), in the mixed solution of concentrated hydrochloric acid and titanium tetrachloride, the concentration of concentrated hydrochloric acid is 0.5M, and the concentration of titanium tetrachloride is 0.1M.

[0023] In one embodiment of the present invention, in step (A3), the post-treatment is specifically as follows:

[0024] After cooling to room temperature, take it out and ultrasonically clean it with ethanol for 10 to 15 minutes, repeat 1 to 3 times, and put it in an oven at 60°C to 100°C to dry it.

[0025] In one embodiment of the present invention, in step (A4), during the calcination process, the heating rate is 5 to 10°C / min, the temperature is 550 to 650°C, and the time is 3 to 4 hours.

[0026] In one embodiment of the present invention, the copper-based Prussian blue framework material having an ion confined structure is prepared by the following method:

[0027] (B1) adding potassium ferrocyanide and copper sulfate dropwise into deionized water, mixing and then standing, and then post-treating and grinding to obtain CuFe PBA powder;

[0028] (B2) grinding the CuFe PBA powder, superconducting carbon black, polyvinylidene fluoride and N-methylpyrrolidone prepared in step (B1) to obtain a mixed slurry;

[0029] (B3) coating the mixed slurry obtained in step (B2) on a conductive carbon cloth, and obtaining a copper-based Prussian blue framework material electrode having an ion confined structure after drying.

[0030] In one embodiment of the present invention, in step (B1), the mass ratio of potassium ferrocyanide, copper sulfate and deionized water is 1:1:500;

[0031] The particle size of the CuFe PBA powder is 10 to 200 nm.

[0032] In one embodiment of the present invention, in step (B1), the mixing time is 0.5 to 1 h, and the standing time is 18 to 30 h;

[0033] The post-treatment is centrifugation, washing and drying in sequence.

[0034] In one embodiment of the present invention, in step (B2), the mass ratio of CuFe PBA powder, superconducting carbon black and polyvinylidene fluoride is 7-8:1-2:1, and the solid content of the mixed slurry is 75-85% (preferably, the mass ratio of CuFe PBA powder, superconducting carbon black and polyvinylidene fluoride is 7:2:1, and the solid content of the mixed slurry is 80%).

[0035] In one embodiment of the present invention, in step (B2), during the grinding process, the rotation speed is 1000 r / min and the time is 5 min.

[0036] In one embodiment of the present invention, in step (B3), the coating amount of the mixed slurry is 1 mg / cm 2 ~100mg / cm 2 ;

[0037] During the drying process, the temperature is 80-120°C and the time is 12-24 hours.

[0038] The present invention realizes efficient selective adsorption and fixation of metal ions by designing an innovative photoelectrochemical system, combining a titanium dioxide (TiO2) photoanode rich in oxygen vacancies and a framework material with an ion confinement structure as a cathode. Under light conditions, the photoelectrochemical system fixes and removes heavy metal ions through an oxidation path at the anode, and at the same time fixes and removes heavy metal ions through an ion embedding path at the cathode, significantly improving the efficiency of heavy metal fixation and removal. The present invention not only improves the removal efficiency of heavy metal ions, but also reduces environmental pollution through resource recovery. It has the advantages of simple operation, low cost, and easy large-scale application, and provides a new and environmentally friendly solution for heavy metal pollution control.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) Innovative dual-path fixation and removal mechanism. The present invention proposes a dual-path heavy metal fixation and removal method driven by a photoelectrochemical process, which combines the unique functions of the photoanode and cathode to achieve efficient fixation and removal of heavy metal ions through an electron-ion coupling mechanism. Heavy metal ions are fixed and removed at the anode through an oxidation path, while heavy metal ions are fixed and removed at the cathode through an ion embedding mechanism. This dual-path fixation and removal mechanism significantly improves the heavy metal removal efficiency and solves the problem that a single photoelectrochemical process is difficult to simultaneously meet the requirements of efficient fixation and removal of heavy metal ions.

[0041] (2) Environmental friendliness and resource recovery. The present invention not only achieves efficient removal of heavy metal ions, but also achieves resource recovery of heavy metals and reduces environmental pollution; the photoelectrochemical reaction process is green and environmentally friendly, avoiding the secondary pollution problem that may be generated in traditional methods, and has the advantages of simple operation, low cost, and easy large-scale application. It provides an innovative and environmentally friendly solution for the treatment of heavy metal-contaminated water bodies, and has broad application prospects and important social and economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of a dual-path heavy metal fixation and removal method driven by a photoelectrochemical process;

[0043] Figure 2 This is a diagram showing the fixation effect of Example 3 of the present invention in simulated heavy metal wastewater (lead nitrate solutions of different concentrations);

[0044] Figure 3 This is a diagram showing the fixation effect of Example 4 of the present invention in simulated heavy metal wastewater (a mixture of lead nitrate and sodium nitrate). DETAILED DESCRIPTION

[0045] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] In the following examples, unless otherwise specified, all reagents used are commercially available reagents, and all detection means and methods used are conventional detection means and methods in the art.

[0047] Example 1

[0048] This embodiment provides a method for preparing a titanium dioxide electrode having oxygen-rich vacancies, comprising the following steps:

[0049] (A1) Add 50 mL of deionized water, 5 mL of concentrated hydrochloric acid and 1 mL of tetrabutyl titanate into a polytetrafluoroethylene liner and mix well to obtain a mixed solution;

[0050] (A2) ultrasonically cleaning the fluorine-doped tin oxide conductive glass (FTO) with deionized water for 10 min, repeated 3 times, and then ultrasonically cleaning it with ethanol for 12 min, repeated 3 times, and drying it in a 60° C. oven. After drying, the conductive surface was tested with a multimeter and marked to obtain pretreated FTO;

[0051] Place the conductive surface of the pretreated FTO facing downward on the upper surface of the mixed solution obtained in step (A1) in the polytetrafluoroethylene liner, then transfer the liner to an autoclave and bake it in an oven at 180°C for 6 hours. After the oven cools to room temperature, take out the FTO grown with TiO2 and ultrasonically clean it with ethanol for 10 minutes, repeat 3 times, and finally dry it in an oven for later use;

[0052] (A3) The FTO grown with TiO2 was immersed in a mixture of 15 mL of concentrated hydrochloric acid and titanium tetrachloride (the concentration of concentrated hydrochloric acid was 0.5 M, and the concentration of titanium tetrachloride was 0.1 M), and then sealed and transferred to an oven at 85°C for 1.5 h. After cooling to room temperature, the oven was taken out and ultrasonically cleaned with ethanol for 10 min, and the process was repeated 3 times. After drying in the oven, an electrode precursor was obtained.

[0053] (A4) The electrode precursor prepared in step (A3) is placed in a crucible, calcined in a muffle furnace, the heating rate is controlled to be 8°C / min, maintained at 600°C for 3.5h, and naturally cooled to room temperature to obtain a titanium dioxide electrode with oxygen-rich vacancies.

[0054] Example 2

[0055] This embodiment provides a method for preparing a copper-based Prussian blue framework material electrode with an ion confined structure, comprising the following steps:

[0056] (B1) 100 mg of potassium ferrocyanide and 100 mg of copper sulfate were slowly added dropwise to 50 mL of deionized water, and then a stirring magnetic bar was added to stir for 0.5 h. The mixture was transferred to a fume hood and allowed to stand for 24 h. After centrifugation, washing, drying, and grinding, a CuFe PBA powder with a particle size of 100 nm was obtained.

[0057] (B2) adding the CuFe PBA powder, superconducting carbon black and polyvinylidene fluoride prepared in step (B1) in a mass ratio of 7:2:1 into an agate mortar, using N-methylpyrrolidone as a solvent, grinding (speed of 1000 r / min, time of 5 min) to obtain a mixed slurry (solid content of 80%);

[0058] (B3) The mixed slurry obtained in step (B2) is evenly coated on the conductive carbon cloth (the coating amount is 50 mg / cm 2 ), and then transferred to a vacuum oven and dried at 100°C for 16 h to obtain a copper-based Prussian blue framework material electrode with an ion-confined structure.

[0059] Example 3

[0060] This embodiment provides a dual-path heavy metal fixation and removal method driven by a photoelectrochemical process, comprising the following steps:

[0061] like Figure 1 As shown, the titanium dioxide electrode with oxygen-rich vacancies prepared in Example 1 is used as a photoanode, and the copper-based Prussian blue framework material electrode with an ion-confined structure prepared in Example 2 is used as a cathode, and the photoanode and the cathode are placed in an electrolyte;

[0062] The simulated heavy metal wastewater (10, 25, 50, 100, 250, 500 and 1000 mg L -1 The electrolyte was lead nitrate solution, and the xenon lamp was used as the simulated sunlight light source (AM1.5, irradiation intensity of 100mW / cm 2 ), photoelectrochemical reaction is carried out under xenon lamp irradiation (react for 5 minutes at room temperature), and heavy metal ions are fixed on the surface of photoanode and cathode (photoanode generates photogenerated electrons and holes under light, where holes participate in the oxidation reaction of anode, react with heavy metal ions in water, oxidize them and convert them into insoluble or low-solubility heavy metal compounds fixed on the surface of photoanode; photogenerated electrons are transmitted to cathode through external circuit, and cathode material uses its ion confinement structure to selectively adsorb and embed heavy metal ions), so as to realize the removal of heavy metals in heavy metal wastewater.

[0063] The results are as follows Figure 2 As shown, through Figure 2 It can be found that in this embodiment, at 10 mg L -1 The fixation rate in lead nitrate solution can reach 62.63%. -1 The fixation rate in lead nitrate solution can reach 600 mg L within 5 min. -1 h -1 .

[0064] Example 4

[0065] This embodiment provides a dual-path heavy metal fixation and removal method driven by a photoelectrochemical process, comprising the following steps:

[0066] The titanium dioxide electrode with oxygen-rich vacancies prepared in Example 1 is used as a photoanode, and the copper-based Prussian blue framework material electrode with an ion-confined structure prepared in Example 2 is used as a cathode, and the photoanode and the cathode are placed in an electrolyte;

[0067] The simulated heavy metal wastewater (a mixture of lead nitrate and sodium nitrate, with a lead nitrate concentration of 100 mg / L and a sodium nitrate concentration of 0.05 mol / L) was used as the electrolyte, and a xenon lamp was used as the simulated sunlight light source (AM1.5, irradiation intensity of 100 mW / cm 2), photoelectrochemical reaction is carried out under xenon lamp irradiation (reaction at room temperature, reaction time is 5 minutes, 10 minutes, 15 minutes, 20 minutes and 30 minutes respectively), heavy metal ions are fixed on the surface of photoanode and cathode (photoanode generates photogenerated electrons and holes under light, the holes participate in the oxidation reaction of anode, react with heavy metal ions in water, oxidize them and convert them into insoluble or low solubility heavy metal compounds fixed on the surface of photoanode; photogenerated electrons are transmitted to cathode through external circuit, cathode material uses its ion confinement structure to selectively adsorb and embed heavy metal ions), so as to realize the removal of heavy metals in heavy metal wastewater.

[0068] The results are as follows Figure 3 As shown, through Figure 3 It can be found that after adding 0.05M sodium nitrate electrolyte in this embodiment, the effect of fixing and removing heavy metal ions in this system is improved, and the fixation rate of lead ions is increased from 23.88% to 28.36%.

[0069] Example 5

[0070] This embodiment provides a method for preparing a titanium dioxide electrode having oxygen-rich vacancies, comprising the following steps:

[0071] (A1) Add 50 mL of deionized water, 2 mL of concentrated hydrochloric acid and 1 mL of tetrabutyl titanate into a polytetrafluoroethylene liner and mix well to obtain a mixed solution;

[0072] (A2) ultrasonically cleaning the fluorine-doped tin oxide conductive glass (FTO) with deionized water for 10 min, repeated 3 times, and then ultrasonically cleaning it with ethanol for 12 min, repeated 3 times, and drying it in a 60° C. oven. After drying, the conductive surface was tested with a multimeter and marked to obtain pretreated FTO;

[0073] The conductive surface of the pretreated FTO was placed downward on the upper surface of the mixed solution obtained in step (A1) in the polytetrafluoroethylene liner, and the liner was transferred to an autoclave and baked in an oven at 150°C for 5 hours. After the oven was cooled to room temperature, the FTO grown with TiO2 was taken out and ultrasonically cleaned with ethanol for 10 minutes, and the process was repeated 3 times. Finally, the FTO was dried in an oven for later use;

[0074] (A3) The FTO grown with TiO2 was immersed in a mixture of 15 mL of concentrated hydrochloric acid and titanium tetrachloride (the concentration of concentrated hydrochloric acid was 0.5 M, and the concentration of titanium tetrachloride was 0.1 M), and then sealed and transferred to a 75°C oven for 2 h. After the oven was cooled to room temperature, it was taken out and ultrasonically cleaned with ethanol for 10 min, and the process was repeated 3 times. After drying in the oven, an electrode precursor was obtained.

[0075] (A4) The electrode precursor prepared in step (A3) is placed in a crucible, calcined in a muffle furnace, the heating rate is controlled to be 5°C / min, maintained at 650°C for 3h, and naturally cooled to room temperature to obtain a titanium dioxide electrode with oxygen-rich vacancies.

[0076] Example 6

[0077] This embodiment provides a method for preparing a titanium dioxide electrode having oxygen-rich vacancies, comprising the following steps:

[0078] (A1) Add 100 mL of deionized water, 2 mL of concentrated hydrochloric acid and 1 mL of tetrabutyl titanate into a polytetrafluoroethylene liner and mix well to obtain a mixed solution;

[0079] (A2) ultrasonically cleaning the fluorine-doped tin oxide conductive glass (FTO) with deionized water for 10 min, repeated 3 times, and then ultrasonically cleaning it with ethanol for 12 min, repeated 3 times, and drying it in a 60° C. oven. After drying, the conductive surface was tested with a multimeter and marked to obtain pretreated FTO;

[0080] Place the conductive surface of the pretreated FTO facing downward on the upper surface of the mixed solution obtained in step (A1) in the polytetrafluoroethylene liner, then transfer the liner to an autoclave and bake it in an oven at 200°C for 3 hours. After the oven cools to room temperature, take out the FTO grown with TiO2 and ultrasonically clean it with ethanol for 10 minutes, repeat 3 times, and finally dry it in an oven for later use;

[0081] (A3) The FTO grown with TiO2 was immersed in 15 mL of a mixture of concentrated hydrochloric acid and titanium tetrachloride (the concentration of concentrated hydrochloric acid was 0.5 M, and the concentration of titanium tetrachloride was 0.1 M), and then sealed and transferred to an oven at 100°C for 1 hour. After the oven was cooled to room temperature, it was taken out and ultrasonically cleaned with ethanol for 10 minutes, and the process was repeated 3 times. After drying in the oven, an electrode precursor was obtained.

[0082] (A4) The electrode precursor prepared in step (A3) is placed in a crucible, calcined in a muffle furnace, the heating rate is controlled to be 10°C / min, maintained at 550°C for 4 hours, and naturally cooled to room temperature to obtain a titanium dioxide electrode with oxygen-rich vacancies.

[0083] The performance of the titanium dioxide electrode with oxygen-rich vacancies prepared in Examples 5 and 6 is comparable to that of the titanium dioxide electrode with oxygen-rich vacancies prepared in Example 1.

[0084] Example 7

[0085] This embodiment provides a method for preparing a copper-based Prussian blue framework material electrode with an ion confined structure, comprising the following steps:

[0086] (B1) 100 mg of potassium ferrocyanide and 100 mg of copper sulfate were slowly added dropwise to 50 mL of deionized water, and then a stirring magnetic bar was added to stir for 0.5 h. The mixture was transferred to a fume hood and allowed to stand for 24 h. After centrifugation, washing, drying, and grinding, a CuFe PBA powder with a particle size of 200 nm was obtained.

[0087] (B2) adding the CuFe PBA powder, superconducting carbon black and polyvinylidene fluoride prepared in step (B1) in a mass ratio of 8:1:1 into an agate mortar, using N-methylpyrrolidone as a solvent, grinding (speed of 1000 r / min, time of 5 min) to obtain a mixed slurry (solid content of 75%);

[0088] (B3) The mixed slurry obtained in step (B2) is evenly coated on the conductive carbon cloth (the coating amount is 50 mg / cm 2 ), and then transferred to a vacuum oven and dried at 120°C for 12 h to obtain a copper-based Prussian blue framework material electrode with an ion-confined structure.

[0089] Example 8

[0090] This embodiment provides a method for preparing a copper-based Prussian blue framework material electrode with an ion confined structure, comprising the following steps:

[0091] (B1) 100 mg of potassium ferrocyanide and 100 mg of copper sulfate were slowly added dropwise to 50 mL of deionized water, and then a stirring magnetic bar was added to stir for 0.5 h. The mixture was transferred to a fume hood and allowed to stand for 24 h. After centrifugation, washing, drying, and grinding, a CuFe PBA powder with a particle size of 10 nm was obtained.

[0092] (B2) adding the CuFe PBA powder, superconducting carbon black and polyvinylidene fluoride prepared in step (B1) in a mass ratio of 7:2:1 into an agate mortar, using N-methylpyrrolidone as a solvent, grinding (speed of 1000 r / min, time of 5 min) to obtain a mixed slurry (solid content of 85%);

[0093] (B3) The mixed slurry obtained in step (B2) is evenly coated on the conductive carbon cloth (the coating amount is 50 mg / cm 2 ), and then transferred to a vacuum oven and dried at 80°C for 24 h to obtain a copper-based Prussian blue framework material electrode with an ion-confined structure.

[0094] The performance of the copper-based Prussian blue framework material electrode with an ion confined structure prepared in Examples 7 and 8 is equivalent to that of the copper-based Prussian blue framework material electrode with an ion confined structure prepared in Example 1.

[0095] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the explanation of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A dual-path heavy metal fixation and removal method driven by a photoelectrochemical process, characterized in that: The following steps are involved: A titanium dioxide electrode with oxygen-rich vacancies is used as a photoanode, a copper-based Prussian blue framework material electrode with an ion-confined structure is used as a cathode, and the electrolyte includes heavy metal wastewater. Photoelectrochemical reactions are carried out under light, and heavy metal ions are fixed on the surfaces of the photoanode and cathode to achieve the removal of heavy metals in heavy metal wastewater.

2. According to claim 1, a dual-path heavy metal fixation and removal method based on photoelectrochemical process driving is characterized in that: The titanium dioxide with oxygen-rich vacancies is prepared by the following method: (A1) mixing deionized water, concentrated hydrochloric acid and tetrabutyl titanate to obtain a mixed solution; (A2) placing the conductive surface of the pretreated FTO downward on the upper surface of the mixed solution obtained in step (A1), baking and performing post-treatment to obtain FTO grown with TiO2; (A3) immersing the FTO grown with TiO2 in a mixed solution of concentrated hydrochloric acid and titanium tetrachloride, and performing post-treatment after baking to obtain an electrode precursor; (A4) The electrode precursor is calcined to obtain a titanium dioxide electrode rich in oxygen vacancies.

3. The dual-path heavy metal fixation and removal method based on photoelectrochemical process drive according to claim 2 is characterized in that: In step (A1), the volume ratio of deionized water, concentrated hydrochloric acid and tetrabutyl titanate is 10-50:2-5:

1.

4. The dual-path heavy metal fixation and removal method based on photoelectrochemical process drive according to claim 2 is characterized in that: In step (A2), during the baking process, the temperature is 150-200° C. and the time is 3-6 hours; In step (A3), during the baking process, the temperature is 75-100° C. and the time is 1-2 hours.

5. The dual-path heavy metal fixation and removal method based on photoelectrochemical process drive according to claim 2 is characterized in that: In step (A4), during the calcination process, the heating rate is 5-10°C / min, the temperature is 550-650°C, and the time is 3-4h.

6. The dual-path heavy metal fixation and removal method based on photoelectrochemical process drive according to claim 1 is characterized in that: The copper-based Prussian blue framework material with an ion-confined structure is prepared by the following method: (B1) adding potassium ferrocyanide and copper sulfate dropwise into deionized water, mixing and then standing, and then post-treating and grinding to obtain CuFe PBA powder; (B2) grinding the CuFe PBA powder, superconducting carbon black, polyvinylidene fluoride and N-methylpyrrolidone prepared in step (B1) to obtain a mixed slurry; (B3) coating the mixed slurry obtained in step (B2) on a conductive carbon cloth, and obtaining a copper-based Prussian blue framework material electrode having an ion confined structure after drying.

7. The dual-path heavy metal fixation and removal method based on photoelectrochemical process drive according to claim 6 is characterized in that: In step (B1), the mass ratio of potassium ferrocyanide, copper sulfate and deionized water is 1:1:500; The particle size of the CuFe PBA powder is 10 to 200 nm.

8. The dual-path heavy metal fixation and removal method based on photoelectrochemical process drive according to claim 6 is characterized in that: In step (B2), the mass ratio of CuFe PBA powder, superconducting carbon black and polyvinylidene fluoride is 7-8:1-2:1, and the solid content of the mixed slurry is 75-85%.

9. The dual-path heavy metal fixation and removal method based on photoelectrochemical process drive according to claim 6 is characterized in that: In step (B3), the coating amount of the mixed slurry is 1 mg / cm 2 ~100mg / cm 2 ; During the drying process, the temperature is 80-120°C and the time is 12-24 hours.

10. The dual-path heavy metal fixation and removal method based on photoelectrochemical process drive according to claim 7, characterized in that: The electrolyte is a mixture of heavy metal wastewater and sodium nitrate.

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