New Materials for Electrochemical Treatment of Complex Pollutants in Mining Areas, Preparation Methods and Applications

Abstract

The invention "New Material for Electrochemical Treatment of Composite Pollutants in Mining Areas, Preparation Method and Application" belongs to the technical field of new materials and their applications. The material for electrochemical treatment is prepared through the following steps: (1) Add malonic acid, acetic anhydride, ammonium molybdate, and ferric sulfate into a reaction vessel, mix and heat to dissolve, and continue to raise the temperature to 135-145°C and maintain for 3-6 hours; (2) After the reaction is completed, add diethyl ether dropwise to precipitate the product, filter by suction, and then wash with diethyl ether and collect the precipitated product; (3) The precipitated product is dried in vacuo to obtain a solid product; (4) The solid product is heated to 300°C in a nitrogen atmosphere, heat-treated at this temperature for 0.5-2 hours, and after cooling to room temperature, a dark red solid material, i.e., the new material, is obtained. As an anode coating material, in the electrochemical degradation process, the removal efficiency of heavy metals in the composite pollutants can reach 100% within 45 minutes, and when treating actual mine groundwater for 120 minutes, the removal efficiency reaches 80.1%.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials and their applications, and particularly relates to a new material for treating composite pollutants in mining areas by an electrochemical process, a preparation method thereof, and an application. Background Art

[0002] With the continuous acceleration of the global economy and industrialization process, the pollution problem in mining areas has become increasingly serious, posing a huge threat to human health and the ecological environment. During the process of ore mining, smelting, and processing, various types of waste will be generated, and these wastes contain multiple pollutants such as heavy metals, organic substances, and inorganic salts. Under specific environmental conditions, there is a possibility of mutual reaction and combination among these substances, thereby generating a large number of composite pollutants with various types and complex properties. Therefore, developing a physical and chemical treatment and resource recovery process for mine composite pollutants has important practical significance and application value.

[0003] Heavy metals can react with coexisting organic ligands, such as ethylenediaminetetraacetic acid (EDTA), citric acid, and oxalic acid in industrial wastewater, thereby forming stable metal-organic complexes. This complexation enhances the stability and solubility of metal ions within a wide pH range and is difficult to effectively treat through conventional strategies such as membrane separation, adsorption, and precipitation because these strategies cannot efficiently break the heavy metal complexes while recovering the free heavy metal ions.

[0004] The electrochemical method for treating heavy metal complexes in wastewater is an ideal method, which has the advantages of simple operation, strong controllability, economic applicability, mild reaction conditions, little environmental impact, and no secondary pollution, and has long been favored by researchers. The advanced oxidation process of peroxydisulfate (PDS) is a feasible method in the field of wastewater treatment. A reasonable catalyst anode material can activate PDS to generate more ROS, thereby improving the treatment efficiency.

[0005] Based on the above status quo, there is an urgent need to develop an ideal anode material suitable for the electrochemical process, so as to promote the wide and efficient application of the electrochemical process in treating underground wastewater pollutants. Summary of the Invention

[0006] In view of the requirements and existing problems in the above fields, the present invention has conducted research and development on the treatment of groundwater composite pollutants with tricarbon dioxide polymer, and based on the research results, the present invention is proposed as follows:

[0007] In the first aspect of the present invention, there is provided a preparation method of a new material for treating composite pollutants in mining areas by an electrochemical process, which is characterized by including the following steps:

[0008] (1) Add malonic acid, acetic anhydride, ammonium molybdate, and ferric sulfate into a reaction vessel, mix and heat to dissolve, and continue to raise the temperature to 135 - 145 °C, and maintain for 3 - 6 hours;

[0009] (2) After the reaction is completed, add diethyl ether dropwise to precipitate the product, filter by suction, and then wash with diethyl ether and collect the precipitated product;

[0010] (3) The precipitated product is dried under vacuum to obtain a solid product;

[0011] (4) Heat the solid product to 300 °C in a nitrogen atmosphere, heat-treat at this temperature for 0.5 - 2 hours, and after cooling to room temperature, obtain a dark red solid material, and obtain an iron-molybdenum modified tricarbon dioxide polymer, that is, the new material.

[0012] Preferably, in the preparation method, in step (1), the molar ratio of malonic acid to acetic anhydride is 1:2, the mass fraction of molybdenum is 1.2%, the mass fraction of iron is 1.3%, the heating and dissolving temperature is 90 °C, and the heating time is 15 minutes.

[0013] Preferably, in the preparation method, in step (4), the heating rate in the nitrogen atmosphere is 5 °C / min.

[0014] Preferably, in the preparation method, in step (4), it further includes grinding after the heat treatment and storing in a dry sample bottle.

[0015] In the second aspect of the present invention, it is requested to protect the new material prepared by any of the above methods.

[0016] In the third aspect of the present invention, it is requested to protect an electrochemical electrode, characterized in that the surface layer material of the electrode is coated with the above new material.

[0017] Preferably, in the electrochemical electrode, the loading amount of the new material is 0.3 - 1.0 mg / cm 2 . The loading amount of the new material is 0.6 mg / cm 2 .

[0018] In the fourth aspect of the present invention, it is requested to protect an electrochemical degradation process for treating complex pollutants in mine groundwater, characterized in that the complex pollutants in the groundwater refer to wastewater polluted by heavy metal complexes in the mining area, containing one or more of Mn, Cr, Cu, Zn, As, Cd, Sb, Pb;

[0019] The electrochemical degradation process includes the following steps:

[0020] (1) Configure an electrochemical degradation cell, wherein the anode electrode uses any of the above electrochemical electrodes;

[0021] (2) Prepare the electrolyte: Take the wastewater contaminated with heavy metal complexes in the mine area to be treated, and add peroxydisulfate and sodium sulfate to prepare it into an electrolyte;

[0022] (3) Connect the power supply to start the reaction.

[0023] Preferably, for the electrochemical degradation process, in step (3), the current is 7.5 mA / cm²; the reaction time is 30 - 120 minutes.

[0024] Preferably, for the electrochemical degradation process, the wastewater contains one or more of Mn, Cr, Cu, Zn, As, Cd, Sb, Pb.

[0025] Preferably, for the electrochemical degradation process, the final concentration of peroxydisulfate in the electrolyte is 5 mM, and the final concentration of sodium sulfate is 50 mM.

[0026] The beneficial effects of the present invention

[0027] The tricarbon dioxide polymer p(C3O2)x is a highly conjugated material formed by the spontaneous polymerization of carbon suboxide (C3O2) at low temperature. Its oxygen-rich framework gives it good acid resistance and good stability in structure. In addition, its synthesis conditions are relatively mild and it is soluble in solvents. The inventor guesses that the above characteristics of the tricarbon dioxide polymer make it an excellent candidate material. Its oxygen-rich carbon framework may provide abundant adsorption or reaction sites, is easy to prepare on a large scale and can be coated on a carrier for water treatment. Based on the above guess, the inventor developed a molybdenum-modified tricarbon dioxide polymer (Mo-p(C3O2)x-300) suitable for the efficient treatment of wastewater by the electrochemical method and studied its application in groundwater treatment.

[0028] In the Fe / Mo-modified tricarbon dioxide polymer provided by the present invention, molybdenum has an adsorption or catalytic conversion effect on heavy metal ions and organic pollutants. At the same time, its oxygen-rich carbon framework may also provide additional adsorption or reaction sites. The electron-rich Fe sites can effectively give electrons for the reduction of PDS, thereby generating more free radicals to attack the complex pollutants. In addition, the low-valent Mo species have strong reducing ability and can reduce Fe 3+ to Fe 2+ , thereby realizing the cycle of Fe and further promoting the oxidant to generate more free radicals to break the complex pollutants. Moreover, under specific conditions, Mo will be converted into MoO4 2-, and then react with heavy metal ions in the solution to form a precipitation reaction, forming an insoluble heavy metal molybdate precipitate, thereby achieving the effective removal of heavy metal ions. This process can achieve the purpose of removing heavy metal ions without the need to additionally introduce chemical precipitants, significantly reducing the cost of wastewater treatment.

[0029] Exemplary embodiment data shows that the Fe / Mo-modified tricarbon dioxide polymer developed in the present invention, as an anode coating material, can achieve a 100% removal efficiency of heavy metals in composite pollutants within 45 minutes in the electrochemical degradation process. When treating mine groundwater for 120 minutes, the removal efficiency is 80.1%. Widely used in the treatment of composite pollutants in mining areas has great environmental and economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 SEM and corresponding mapping diagrams of Fe / Mo-p(C3O2) prepared in Example 1 of the present invention x

[0031] Figure 2 SEM and corresponding mapping diagrams of Fe / Mo-p(C3O2) prepared in Example 1 of the present invention x -300

[0032] Figure 3 The Fe / Mo-p(C3O2) provided by the present invention x -300 Test results of removing metal-organic complexes by electrochemical degradation process, where the ordinate C / C0 represents the removal ratio of Pb-EDTA; the abscissa represents the treatment time.

[0033] Figure 4 The Fe / Mo-p(C3O2) provided by the present invention x -300 Test results of removing heavy metals in mine underground wastewater by electrochemical degradation process, where the ordinate represents the lead concentration in groundwater; the abscissa represents the treatment time. DETAILED DESCRIPTION OF THE INVENTION

[0034] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited thereto.

[0035] Example 1 Preparation of the Fe / Mo-modified tricarbon dioxide polymer of the present invention

[0036] To prepare the Fe and Mo-modified tricarbon dioxide polymer of the present invention, the following steps are carried out:

[0037] 1. Mix malonic acid and acetic anhydride in a molar ratio of 1:2, and add ammonium molybdate and ferric sulfate so that the mass fraction of molybdenum in the mixture is 1.2% and the mass fraction of iron is 1.3%. Heat the mixture to 90 °C and keep it for 15 minutes.

[0038] 2. Then raise the temperature to 140 °C and keep it for 5 hours. Slowly drip ether into the flask to precipitate the product until the precipitation is complete. Filter by suction, wash three times with ether, and collect the solid product.

[0039] 3. Place the product in a vacuum drying oven and dry it overnight to obtain a solid product, denoted as Fe / Mo-p(C3O2)x.

[0040] 4. Transfer 1 g of Fe / Mo-p(C3O2)x to a porcelain boat, heat it in a nitrogen atmosphere at a heating rate of 5 °C / min and perform heat treatment at 300 °C for 1 hour. After cooling to room temperature, collect the solid product, Fe / Mo-modified tricarbon dioxide polymer, denoted as Fe / Mo-p(C3O2)x-300. Grind this solid product to pass through a 200-mesh sieve for standby.

[0041] The Fe / Mo-p(C3O2)x-300 obtained by calcination can avoid or reduce the dissolution of catalyst Mo during the treatment of sewage.

[0042] 5. Detect and characterize the product:

[0043] Detect the solid products Fe / Mo-p(C3O2)x and Fe / Mo-p(C3O2)x-300 obtained in steps 3 and 4 by using a scanning electron microscope (SEM) and elemental distribution mapping (mapping).

[0044] The results are as Figure 1 and Figure 2 shown. The elemental distribution mapping results prove that the solid products Fe / Mo-p(C3O2)x and Fe / Mo-p(C3O2)x-300 obtained in the present invention are composed of four elements: Fe, Mo, C, and O. At the same time, the scanning electron microscope detection shows ( Figure 1 upper left and Figure 2 upper left) that there are significant differences in the morphology between Fe / Mo-p(C3O2)x and Fe / Mo-p(C3O2)x-300.

[0045] Example 2 Performance test of the Fe / Mo-modified tricarbon dioxide polymer of the invention

[0046] The Fe / Mo-modified tricarbon dioxide polymer Fe / Mo-p(C3O2)x-300 of Example 1 of the present invention is used at 0.6 mg / cm 2The load ratio was drop-coated onto the anode carbon felt and subjected to electrochemical constant current testing in an electrolyte (0.0278 g of lead chloride and 0.0372 g of disodium ethylenediaminetetraacetate dihydrate were weighed into a 1 L volumetric flask, 1000 ml of ultrapure water was added and stirred to dissolve, i.e., containing 65 mg / L Pb-EDTA; persulfate 5 mM, sodium sulfate 50 mM).

[0047] The specific steps are as follows:

[0048] Step 1 Pretreatment of the carbon felt:

[0049] The carbon felt was cut into 1×2 cm 2 , soaked in nitric acid for 6 h, then ultrasonically treated with acetone, ethanol, and deionized water for 30 minutes each, and dried at 70 °C for 12 hours

[0050] Step 2 Preparation of the working electrode

[0051] 5 mg of Fe / Mo-p(C3O2) x -300 was dispersed in a solution obtained by mixing 0.3 mL of water, 0.7 mL of ethanol, and 0.02 mL of Nafion 117, and treated ultrasonically for 30 minutes to obtain a catalyst solution.

[0052] The catalyst solution was dropped onto the carbon felt, and the loading amount of Fe / Mo-p(C3O2) x -3000 on the carbon felt was 0.6 mg / cm 2 .

[0053] Step 3 Setup of the reaction device

[0054] Using the carbon felt drop-coated with Fe / Mo-p(C3O2) x -300 as the working electrode, and connecting another carbon felt to the counter electrode;

[0055] 80 ml of the above electrolyte was taken and added to a 100 ml electrolytic cell to start the reaction, and the current was set to 7.5 mA / cm 2 , and the reaction time was 1.5 h.

[0056] Step 4 Reaction detection

[0057] At regular intervals, the supernatant was taken with a syringe, filtered through a microporous membrane, and the content of the remaining Pb-EDTA in the sample was determined by liquid chromatography. After the reaction ended, a small amount of the solution was taken for atomic absorption testing to measure the concentration of the remaining lead ions.

[0058] The removal effect of the Fe / Mo-modified tricarbon dioxide polymer provided by the present invention on Pb-EDTA is as Figure 3As shown, the vertical axis C / C0 represents the removal rate (%), and the horizontal axis t / min represents the treatment time. 2 When the loading amount is 2.5, the removal rate of heavy metal-organic complex Pb-EDTA with a concentration of 65 mg / L reaches 100% within 45 minutes.

[0059] Example 3 Practical application demonstration of actual mine underground wastewater

[0060] Step 1 Pretreatment of wastewater to be treated

[0061] 1. Collect samples: Collect representative wastewater samples from the mine’s underground wastewater discharge outlet or contaminated area to ensure that the samples can accurately reflect the pollution status of the mine’s underground wastewater.

[0062] 2. Preliminary analysis: Conduct preliminary analysis on the collected wastewater samples to determine the content of heavy metals, COD value, pH value and other basic parameters in order to understand the pollution degree and characteristics of the wastewater. The measurement data are as follows

[0063]

[0064] 3. Filtration: If there are a lot of suspended solids in the wastewater sample, you can first filter it with filter paper or microporous filter membrane to remove large particles of suspended solids;

[0065] Step 2 Preparation of working electrode

[0066] 1. Carbon felt pretreatment: Cut the carbon felt into 1×2cm² and soak it in nitric acid for 6 hours to remove impurities and oil stains on the surface of the carbon felt. Then, ultrasonically treat it with acetone, ethanol and deionized water for 30 minutes respectively to further clean the carbon felt, and finally dry it at 70℃ for 12 hours.

[0067] 2. Catalyst solution preparation: 5 mg of Fe / Mo-p(C3O2) x -300 is dispersed in 0.3 mL of water, 0.7 mL of ethanol and 0.02 mL of Nafion 117 solution (or expanded according to this ratio), and the mixed solution is treated under ultrasonication for 30 minutes to obtain a uniform catalyst solution.

[0068] 3. Catalyst drop coating: Take the catalyst solution and evenly drop it on the pretreated carbon felt to ensure that the catalyst coating area is 1×1 cm². Then place the drop-coated carbon felt in a drying oven and dry it at 60°C for 30 minutes to make the catalyst firmly adhere to the surface of the carbon felt to obtain a working electrode.

[0069] Step 3: Construction of the reaction device

[0070] 1. Electrode preparation: Use the working electrode coated with the catalyst prepared in Step 2 as the anode, and another carbon felt without the catalyst coating as the cathode.

[0071] 2. Electrolytic cell assembly: Select an electrolytic cell of appropriate specifications, place the anode and cathode parallel to each other in the same chamber of the electrolytic cell, and keep a distance of 2 cm between the two electrodes to ensure the smooth progress of the electrochemical reaction.

[0072] 3. Electrolyte preparation: Use the underground mine wastewater to prepare the electrolyte. The initial lead concentration is measured to be 25 mg / L. Add peroxydisulfate and sodium sulfate to make the final concentration of peroxydisulfate in the electrolyte 5 mM and the final concentration of sodium sulfate 50 mM.

[0073] Step 4 Reaction detection

[0074] 1. Start the reaction: Connect the power supply, apply a constant current of 7.5 mA / cm² to the electrolytic cell, and record the start time of the reaction.

[0075] 2. Regular sampling: At regular intervals, use a syringe to extract a certain amount of supernatant from the electrolytic cell. After filtering through a 0.22 μm microporous filter membrane, collect the filtrate for subsequent analysis and detection.

[0076] 3. Analysis and detection: Use an atomic absorption spectrometer to measure the concentration of the remaining heavy metal ions in the filtrate. The detection data are as Figure 4 shown. The initial lead concentration is 22.6 mg / L, and it can be reduced to a minimum of 4.34 mg / L after 120 minutes of treatment, with a removal efficiency of 80.1%.

[0077] The above exemplary implementation data show that the new material Fe / Mo-p(C3O2) x -300 is an excellent candidate material in the process of removing heavy metals from complex pollutants through the electrochemical degradation process and has wide application value.

Claims

1. A new material for treating heavy metal composite pollutants in groundwater in mining areas by electrochemical process, characterized in that: Prepared by the following steps: (1) Add malonic acid, acetic anhydride, ammonium molybdate and ferric sulfate into a reaction vessel, mix and heat to dissolve, and continue to raise the temperature to 135-145° C. and maintain for 3-6 hours; (2) After the reaction is completed, add ether dropwise to precipitate the product, filter it with suction, then wash it with ether and collect the precipitated product; (3) The precipitated product is vacuum dried to obtain a solid product; (4) The solid product is heated to 300° C. in a nitrogen atmosphere, heat treated at this temperature for 0.5 to 2 hours, and cooled to room temperature to obtain a dark red solid material, namely, an iron-molybdenum-modified carbon dioxide polymer, i.e., the new material.

2. The new material according to claim 1, characterized in that: In step (1), the molar ratio of malonic acid to acetic anhydride is 1:2, the mass fraction of molybdenum is 1.2%, the mass fraction of iron is 1.3%, the temperature for heating and dissolving is 90°C, and the heating time is 15 minutes.

3. The new material according to claim 1, characterized in that: In step (4), the heating rate in the nitrogen atmosphere is 5°C / min.

4. The new material according to claim 1, characterized in that: Step (4) further includes grinding after the heat treatment and storing the mixture in a dry sample bottle.

5. An electrochemical electrode, characterized in that The surface material of the electrode is coated with the new material described in any one of claims 1 to 4.

6. The electrochemical electrode according to claim 5, characterized in that The coating amount of the new material is 0.3-1.0 mg / cm 2 .

7. An electrochemical degradation process for treating heavy metal composite pollutants in groundwater in mining areas, characterized in that: The heavy metals are one or more of Mn, Cr, Cu, Zn, As, Cd, Sb and Pb; The electrochemical degradation process comprises the following steps: (1) An electrochemical degradation cell is provided, wherein the electrochemical electrode according to claim 5 or 6 is used as an anode electrode; (2) Preparation of electrolyte: Take the wastewater from the mining area to be treated, add peroxodisulfate and sodium sulfate to prepare the electrolyte; (3) Turn on the power to start the reaction.

8. The electrochemical degradation process according to claim 7, characterized in that: The current applied in step (3) is 7.5 mA / cm²; the reaction time is 30 to 120 minutes.

9. The electrochemical degradation process according to claim 7, characterized in that: The final concentration of peroxodisulfate in the electrolyte was 5 mM, and the final concentration of sodium sulfate was 50 mM.

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