Method for simultaneous removal of As(V) and Sb(V) by electrochemical in-situ mineralization

Abstract

The present invention discloses a method for simultaneously removing As(V) and Sb(V) by electrochemical in-situ mineralization, comprising the following steps: placing acid mine wastewater in a container, and inserting an anode electrode and a cathode electrode to form a double-electrode electrolytic cell; performing an electrochemical reaction by a constant current method, and filtering the generated precipitate; wherein the anode electrode is used to remove Fe(V) in the acid mine wastewater; 2+ Oxidized to Fe 3+ ; The cathode electrode is used to reduce oxygen to generate OH ‑ The electrochemical reaction is performed in chronopotentiometry mode. This method uses electrochemical means to directly generate Schroeder mineral in acidic mine wastewater. During the precipitation process, As(V) and Sb(V) are entrained into the Schroeder mineral lattice, forming a co-precipitation. Through the combined effects of co-precipitation and adsorption, As(V) and Sb(V) are removed from the aqueous phase. This method achieves significant removal efficiency and is simple, without the need for complex adsorbent preparation or the addition of exogenous reagents.

Description

Technical Field

[0001] The present invention belongs to the technical field of heavy metal removal, and in particular relates to a method for simultaneously removing As(V) and Sb(V) through electrochemical in-situ mineralization. Background Art

[0002] Arsenic (As) and antimony (Sb) are typical toxic heavy metal pollutants from the same group (Group 15) of the periodic table, presenting significant biotoxicity and health risks. In aerobic environments, such as surface water, As and Sb primarily exist as pentavalent arsenic (As(V)) and pentavalent antimony (Sb(V)). As and Sb share similar chemical properties and are therefore often found in sulfide deposits (such as realgar and stibnite). During mining, smelting, and industrial activities, As and Sb are widely present as combined pollutants in acid mine drainage (AMD), tailings pond leachate, smelting wastewater, and industrial wastewater.

[0003] Due to their environmental coexistence characteristics and treatment efficiency requirements, the synergistic removal of As and Sb in acid mine drainage has received widespread attention both at home and abroad, with adsorption and microbial remediation being the main means. However, most of the adsorption methods that are the focus of existing technologies rely on the addition of exogenous reagents or complex adsorbent preparation processes, which leads to increased costs or insufficient engineering adaptability, and it is necessary to be vigilant about the secondary pollution that may be caused by adsorbents; although microbial remediation technology is environmentally friendly, it has strict requirements on the microbial growth environment, a long remediation cycle, and is not suitable for severely polluted areas (the toxicity of high concentrations of As and Sb inhibits microbial activity). As a naturally formed sulfate secondary iron mineral in the acid mine drainage environment, the mineralization process of Schmidt's mineral is closely related to the acidic environment of acid mine drainage (pH = 2–4), high Fe (II / III), and high SO4 2- The concentration and redox conditions are highly coupled, and it has natural mineral-water interface adaptability and environmental compatibility. In addition, the unique pore topology and exchangeable state structure of Schmidt mineral SO4 2- Characteristics such as the presence of hydroxyl-rich sites endow Schroeder's minerals with a remarkable ability to immobilize oxygen-containing anion pollutants such as As(V) and Sb(V). However, Schroeder's minerals, formed through natural processes such as light irradiation and microbial oxidation, suffer from low mineralization rates and uncontrollable mineralization processes, limiting their ability to immobilize coexisting pollutants.

[0004] Chinese patent application CN202010142704.9 discloses a method for the rapid electrochemical deposition synthesis of Schroeder mineral. The synthesized Schroeder mineral exhibits high specific surface area, uniform particle size, a typical sea urchin spherical microstructure, and abundant surface whiskers. However, this method addresses the technical challenge of obtaining Schroeder mineral with a high degree of crystallinity, and the method is not very effective in fixing As and Sb during the mineralization process. Summary of the Invention

[0005] Based on this, the present invention provides a method for simultaneously removing As(V) and Sb(V) by electrochemical in-situ mineralization, the method comprising the following steps:

[0006] (1) Place acid mine drainage in a container and insert an anode electrode and a cathode electrode to form a two-electrode electrolytic cell;

[0007] (2) Under magnetic stirring conditions, the electrochemical reaction is carried out by constant current method, and the generated precipitate is filtered;

[0008] In step (1), the anode battery is used to convert Fe 2+ Oxidized to Fe 3+ ; The cathode cell is used to reduce oxygen to generate OH - ;

[0009] In step (2), the electrochemical reaction is performed in chronopotentiometry mode, with the cathode current set to 0 mA, the anode current to 180-220 mA, the cathode time to 0 s, and the anode time to 7200-10800 s. More preferably, the anode time is 9000-10800 s. Further preferably, the anode current is 190-210 mA.

[0010] The principle of the electrochemical reaction of the present invention is to promote the oxidation of Fe(II) in acidic mine wastewater at the anode by electrochemical means and adopt constant current method, and at the same time promote the reduction of oxygen at the cathode to generate OH - The increase in pH promotes the hydrolysis of Fe(III) generated at the anode and the original Fe(III) in the acidic mine wastewater. 2- Under the regulation of the reaction, Schmidt minerals are generated, and during the precipitation process, As(V) and Sb(V) are entrained into the Schmidt mineral lattice to form a co-precipitation. The generated Schmidt minerals further fix the remaining As(V) and Sb(V) in the solution through adsorption. Under the combined action of co-precipitation and adsorption, As(V) and Sb(V) in the aqueous phase are removed together. Figure 1 .

[0011] In the present invention, the Schmidt mineral generated by electrochemical reaction has a unique pore topology and an exchangeable state structure SO4 2- , especially the characteristics of hydroxyl-rich sites, which give Schmidt minerals a significant ability to fix oxygen-containing anion pollutants such as As(V) and Sb(V), and can greatly reduce the mobile As(V) and Sb(V) in wastewater at the same time. This method does not require a complicated adsorbent preparation process and does not require the addition of exogenous agents. The process is simple and easy to operate.

[0012] In the present invention, the design of hydroxyl-rich sites significantly increases the fixation capacity of Schroeder mineral for As(V) and Sb(V), especially the fixation and removal of Sb(V). More preferably, without the addition of exogenous reagents, As(V) and Sb(V) are removed simultaneously by electrochemical reaction while Schroeder mineral is generated; in addition, the Fe and SO4 in acid mine drainage are also reduced. 2- and H + content, realizing in-situ purification of wastewater.

[0013] In step (2) of the present invention, the magnetic stirring rate is preferably 60-100 rpm.

[0014] According to the method for simultaneous removal of As(V) and Sb(V) by electrochemical in situ mineralization according to claim 1, preferably, in step (1), the acid mine drainage further includes a pretreatment step, and the pretreatment step is to remove suspended particulate matter in the water body by filtering through a microporous membrane.

[0015] According to the method for simultaneous removal of As(V) and Sb(V) by electrochemical in-situ mineralization according to claim 1, preferably, in step (1), the anode electrode is Coated titanium-based electrodes, The cathode electrode is any one of a 304 stainless steel electrode or a Pt electrode. More preferably, the anode electrode is The coated titanium-based electrode and the cathode electrode are 304 stainless steel electrodes.

[0016] According to the method for electrochemical in-situ mineralization and simultaneous removal of As(V) and Sb(V) according to claim 1, preferably, in step (1), the anode electrode undergoes an anode pretreatment step, and the anode pretreatment step is: soaking the anode electrode in a 10-15% citric acid solution for 20-40 min to perform pickling to remove surface oxides, then rinsing it with deionized water, and finally blowing it dry with nitrogen.

[0017] According to the method for electrochemical in-situ mineralization and simultaneous removal of As(V) and Sb(V) according to claim 1, preferably, in step (1), the cathode electrode undergoes a cathode pretreatment step, and the cathode pretreatment step is: polishing the cathode electrode with 1000-1500 mesh sandpaper to remove the passivation layer, then ultrasonically cleaning it with acetone, ethanol, and deionized water in sequence, and finally blowing it dry with nitrogen.

[0018] According to the method for simultaneous removal of As(V) and Sb(V) by electrochemical in-situ mineralization according to claim 1, preferably, in step (1), the As(V) content in the acid mine drainage water is 0.1-100 mg / L. More preferably, as a more preferred embodiment of the present invention, the As(V) content in the acid mine drainage water is 2-10 mg / L; further preferably, the As(V) content in the acid mine drainage water is 3-8 mg / L.

[0019] According to the method for simultaneous removal of As(V) and Sb(V) by electrochemical in-situ mineralization according to claim 1, preferably, in step (1), the content of Sb(V) in the acid mine wastewater is 0.1-150 mg / L.

[0020] As another embodiment of the present invention, the Sb(V) content in the acid mine drainage water is 1-20 mg / L. Using wastewater with the above Sb(V) content concentration range, the Sb(V) removal rate reaches more than 99%.

[0021] As a preferred embodiment of the present invention, the As(V) content in the acidic mine drainage water is 1-15 mg / L, and the Sb(V) content in the acidic mine drainage water is 1-50 mg / L. As a more preferred embodiment of the present invention, the As(V) content in the acidic mine drainage water is 2-10 mg / L, and the Sb(V) content in the acidic mine drainage water is 10-40 mg / L. As a more preferred embodiment of the present invention, the As(V) content in the acidic mine drainage water is 3-8 mg / L, and the Sb(V) content in the acidic mine drainage water is 15-35 mg / L. The electrochemical method of the present invention is more suitable for removing As(V) and Sb(V) from acidic mine drainage water within the above-mentioned concentration ranges.

[0022] According to the method for simultaneous removal of As(V) and Sb(V) by electrochemical in situ mineralization according to claim 1, preferably, in step (1), the total Fe content in the acid mine drainage water is 200-1000 mg / L.

[0023] As a preferred embodiment of the present invention, the total content of total Fe in the acid mine drainage water is 300-1000 mg / L; further preferably, the total content of total Fe in the acid mine drainage water is 500-800 mg / L.

[0024] According to the method for simultaneous removal of As(V) and Sb(V) by electrochemical in-situ mineralization according to claim 1, preferably, in step (1), SO4 2- The content is 1000-3000 mg / L.

[0025] As a preferred embodiment of the present invention, the SO4 2- The content of SO4 in the acid mine wastewater is 1500-3000 mg / L; further preferably, the SO4 2- The content is 2000-3000 mg / L.

[0026] As a specific embodiment of the present invention, the As(V) content in the acid mine wastewater is 1-15 mg / L, the Sb(V) content in the acid mine wastewater is 1-50 mg / L, the total Fe content in the acid mine wastewater is 300-1000 mg / L, and the SO4 2- The content of As(V) in the acid mine wastewater is 1500-3000 mg / L; as a further preferred embodiment of the present invention, the content of As(V) in the acid mine wastewater is 2-10 mg / L, the content of Sb(V) in the acid mine wastewater is 10-40 mg / L, the total content of Fe in the acid mine wastewater is 500-800 mg / L, and the content of SO4 in the acid mine wastewater is 200-3000 mg / L. 2- The content is 2000-3000 mg / L. Treating wastewater within the above range can not only effectively remove As(V) and Sb(V), but also reduce Fe and SO4 in acid mine wastewater. 2- and H + Content, especially SO4 2- The removal effect is more significant.

[0027] According to the method for simultaneous removal of As(V) and Sb(V) by electrochemical in situ mineralization according to claim 1, preferably, in step (1), the pH value of the acid mine drainage is 2-4. More preferably, the pH value of the acid mine drainage is 3-4.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The method of the present invention uses electrochemical means and a constant current method to generate Schrödinger mineral in acidic mine wastewater without adding exogenous agents. During the precipitation process, As(V) and Sb(V) are entrained into the Schrödinger mineral lattice to form a co-precipitation. The generated Schrödinger mineral further fixes the remaining As(V) and Sb(V) in the solution through adsorption. Under the combined action of coprecipitation and adsorption, As(V) and Sb(V) in the aqueous phase are jointly removed. The method has a significant removal effect, does not require a complex adsorbent preparation process, does not require the addition of exogenous agents, and has a simple process and is easy to operate.

[0030] In addition, the method of the present invention also reduces Fe, SO4 2- and H+ content, realizing in-situ purification of wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a working principle diagram of a method for simultaneously removing As(V) and Sb(V) by electrochemical in-situ mineralization according to the present invention.

[0032] Figure 2 This is a method for the simultaneous removal of As(V) and Sb(V) by electrochemical in-situ mineralization according to the present invention, and a graph showing the change in the main components of the electrolytic sheet over time during a constant current electrochemical reaction in acidic mine wastewater with different As(V) and Sb(V) concentrations.

[0033] Figure 3 This is a method for the simultaneous removal of As(V) and Sb(V) by electrochemical in situ mineralization according to the present invention. The X-ray diffraction patterns of solid particles obtained after a 3-hour constant current electrochemical reaction in acidic mine wastewater with different As(V) and Sb(V) concentrations are shown. The symbol marks the characteristic peaks of Schmidt's mineral. DETAILED DESCRIPTION

[0034] To facilitate understanding of the present invention, the present invention will be described more fully below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the content of the present invention more thoroughly and comprehensively understood.

[0035] Electrode Description

[0036] In the present invention, the MMO anode (i.e. The MMO anode and 304 stainless steel cathode were purchased from Suzhou Shuertai Industrial Technology Co., Ltd., with a size of 30 mm × 30 mm. The following method was used to treat the MMO anode and 304 stainless steel cathode:

[0037] Treatment of MMO anode: First, soak the MMO electrode with a size of 30 mm × 30 mm in 10% citric acid solution for 30 minutes for pickling to remove surface oxides, then rinse it with deionized water, and finally blow dry with nitrogen.

[0038] Preparation of 304 stainless steel cathode: A 304 stainless steel electrode with a size of 30 mm × 30 mm was polished with 1500-grit sandpaper to remove the passivation layer, and then ultrasonically cleaned with acetone, ethanol, and deionized water in sequence, and finally dried with nitrogen.

[0039] Experimental method for preparing acid mine drainage:

[0040] Preparation of As(V) stock solution: Use an analytical balance (accuracy 0.0001g) to accurately weigh 2.1196g of sodium arsenate dodecahydrate (Na3AsO4·12H2O) and dissolve it in deionized water and dilute to 1L to obtain a 5 mM As(V) stock solution;

[0041] Preparation of Sb(V) stock solution: Accurately weigh 1.3146 g of potassium pyroantimonate (KSb(OH)6) using an analytical balance (accuracy 0.0001 g) and dissolve it in 500 mL of 60°C deionized water. After cooling to room temperature, transfer the solution to a volumetric flask. Rinse the beaker three times with pure water, add the washings to the volumetric flask, and adjust the volume to 1 L to obtain a 5 mM Sb(V) stock solution.

[0042] Preparation of acid mine drainage: 2.78 g of ferrous sulfate heptahydrate (FeSO4·7H2O), 1.42 g of anhydrous sodium sulfate (Na2SO4), a certain amount of As(V) stock solution, and a certain amount of Sb(V) stock solution were dissolved in deionized water and the volume was adjusted to 1 L. The pH of the solution was adjusted to 3.0 with dilute sulfuric acid and sodium hydroxide to obtain acid mine drainage containing different As(V) and Sb(V) concentrations. The As(V) and Sb(V) concentrations in the acid mine drainage were adjusted by adjusting the amount of As(V) stock solution and Sb(V) stock solution added.

[0043] Content determination method and removal rate calculation method:

[0044] Determination method of ingredient content:

[0045] The suspension after the electrochemical reaction is filtered through a microporous filter membrane to obtain a filtrate and a solid precipitate. The solid precipitate is freeze-dried and then ground through a 200-mesh sieve to obtain solid phase particles.

[0046] Inductively coupled plasma-atomic emission spectrometry (ICP-AES) was used to determine the As and Sb element contents and the total Fe content in the filtrate;

[0047] The Fe(II) content in the filtrate was determined by ultraviolet-visible spectrophotometry (UV-Vis);

[0048] The content of SO42- in the filtrate was determined by anion chromatography (IC);

[0049] The solid phase particles were measured by X-ray diffraction spectrometer (XRD) to determine the composition of the solid phase particles.

[0050] The removal rates of As(V) and Sb(V) were obtained by the following formula:

[0051] Removal rate = (C0-C t ) / C0×100%,

[0052] Where C0 represents the initial As(V) or Sb(V) concentration;

[0053] C t Represents the concentration of As(V) or Sb(V) when the reaction reaches time t. Example 1

[0054] A method for simultaneously removing As(V) and Sb(V) by electrochemical in-situ mineralization in this embodiment includes the following steps:

[0055] (1) 300 mL of acidic mine wastewater solution containing 0.75 mg / L As(V) and 1.22 mg / L Sb(V) was added to a 500 mL cylindrical glass electrolytic cell. A magnetron was placed in the electrolytic cell. The reaction was stirred at 80 rpm. The treated MMO anode and 304 stainless steel cathode were inserted into the electrolytic cell.

[0056] (2) Connect the computer to the electrochemical workstation (CHI 660E, Shanghai Chenhua) and use the constant current method to perform the electrochemical reaction. The specific operation is: select the chronopotentiometry mode, set the cathode current to 0 mA, the anode current to 200 mA, the cathode time to 0 s, and the anode time to 10800 s.

[0057] At the electrochemical reaction time of 0, 5, 10, 30, 60, 90, 120, 150, and 180 min, 3 mL of sample was taken through a 0.22 μm needle filter membrane, and the Fe(II), As, Sb, and SO4 in the filtrate were determined by UV-Vis, ICP-AES, and IC methods, respectively. 2- The content of the four substances in the solution is obtained by the time-varying rate of change, such as Figure 2 shown.

[0058] After the reaction, the resulting suspension was filtered through a 0.22 μm filter membrane, and the resulting solid precipitate was freeze-dried for 48 h, then ground and passed through a 200-mesh sieve. The solid phase composition was detected by XRD. The XRD results are shown in Figure 2. Figure 3 As shown, it is consistent with the characteristics of Schmidt mineral.

[0059] Removal efficiency of As(V) and Sb(V): After 3 h of reaction, the As and Sb contents in the solution were 0.002 mg / L and 0.009 mg / L, respectively. The As(V) removal rate was (0.75-0.002) / 0.75×100% = 99.7%, and the Sb(V) removal rate was (1.22-0.009) / 1.22×100% = 99.3%. Example 2

[0060] A method for simultaneously removing As(V) and Sb(V) by electrochemical in-situ mineralization in this embodiment includes the following steps:

[0061] (1) 300 mL of acidic mine wastewater solution containing 7.5 mg / L As(V) and 12.2 mg / L Sb(V) was added to a 500 mL cylindrical glass electrolytic cell. A magnetron was placed in the electrolytic cell. During the reaction, the reaction was stirred at 80 rpm. The treated MMO anode and 304 stainless steel cathode were inserted into the electrolytic cell.

[0062] (2) Connect the computer to the electrochemical workstation (CHI 660E, Shanghai Chenhua) and use the constant current method to perform the electrochemical reaction. The specific operation is: select the chronopotentiometry mode, set the cathode current to 0 mA, the anode current to 200 mA, the cathode time to 0 s, and the anode time to 10800 s.

[0063] At the electrochemical reaction time of 0, 5, 10, 30, 60, 90, 120, 150, and 180 min, 3 mL of sample was taken through a 0.22 μm needle filter membrane, and the Fe(II), As, Sb, and SO4 in the filtrate were determined by UV-Vis, ICP-AES, and IC methods, respectively. 2- The content of the four substances in the solution is obtained by the time-varying rate of change, such as Figure 2 shown.

[0064] After the reaction, the resulting suspension was filtered through a 0.22 μm filter membrane, and the resulting solid precipitate was freeze-dried for 48 h, then ground and passed through a 200-mesh sieve. The solid phase composition was detected by XRD. The XRD results are shown in Figure 2. Figure 3 As shown, it is consistent with the characteristics of Schmidt mineral.

[0065] Removal efficiency of As(V) and Sb(V): After 3 h of reaction, the As and Sb contents in the solution were 0.019 mg / L and 0.083 mg / L, respectively. The As(V) removal rate was (7.5-0.029) / 7.5×100% = 99.6%, and the Sb(V) removal rate was (12.2-0.043) / 12.2×100% = 99.6%. Example 3

[0066] A method for simultaneously removing As(V) and Sb(V) by electrochemical in-situ mineralization in this embodiment includes the following steps:

[0067] (1) 300 mL of acidic mine wastewater solution containing 75 mg / L As(V) and 122 mg / L Sb(V) was added to a 500 mL cylindrical glass electrolytic cell. A magnetron was placed in the electrolytic cell. During the reaction, the reaction was stirred at 80 rpm. The treated MMO anode and 304 stainless steel cathode were inserted into the electrolytic cell.

[0068] (2) Connect the computer to the electrochemical workstation (CHI 660E, Shanghai Chenhua) and use the constant current method to perform the electrochemical reaction. The specific operation is: select the chronopotentiometry mode, set the cathode current to 0 mA, the anode current to 200 mA, the cathode time to 0 s, and the anode time to 10800 s.

[0069] At the electrochemical reaction time of 0, 5, 10, 30, 60, 90, 120, 150, and 180 min, 3 mL of samples were taken through a 0.22 μm needle filter membrane, and the contents of Fe(II), As, Sb, and SO42- in the filtrate were determined by UV-Vis, ICP-AES, and IC methods, respectively. The change rates of the contents of the four substances in the solution with time were obtained, as shown in Fig. Figure 2 shown.

[0070] After the reaction, the resulting suspension was filtered through a 0.22 μm filter membrane, and the resulting solid precipitate was freeze-dried for 48 h, then ground and passed through a 200-mesh sieve. The solid phase composition was detected by XRD. The XRD results are shown in Figure 2. Figure 3 As shown, it is consistent with the characteristics of Schmidt mineral.

[0071] Removal efficiency of As(V) and Sb(V): After 3 h of reaction, the As and Sb contents in the solution were 2.87 mg / L and 2.81 mg / L, respectively. The As(V) removal rate was (75-2.87) / 75×100% = 96.2%, and the Sb(V) removal rate was (122-2.81) / 122×100% = 97.7%. Example 4

[0072] This example describes a method for the simultaneous removal of As(V) and Sb(V) by electrochemical in situ mineralization. The steps are identical to those of Example 1, except for the use of different acid mine wastewater. In this example, the acid mine wastewater was obtained by filtering surface runoff from the downstream Xikuangshan mining area in Hunan Province through a 0.22 μm filter membrane. The main component contents are shown in Table 1.

[0073] After 3 h of reaction, the contents of As and Sb in the filtrate were 0.12 mg / L and 1.17 mg / L, respectively, and the removal rates of As(V) and Sb(V) were 97.4% and 95.9%, respectively.

[0074] Table 1 Water quality characteristics of acid mine drainage in Example 4

[0075] Main parameters Numerical pH 2.9 Total Fe (mg / L) 632.7 Fe(II) (mg / L) 75.4 <![CDATA[SO4 2- (mg / L)]]> 2635.8 As(V) (mg / L) 4.6 Sb(V) (mg / L) 28.7

[0076] Comparative Example 1

[0077] The acid mine wastewater of Example 1 was treated by the electrochemical method described in Chinese patent application CN202010142704.9. The As and Sb contents in the filtrate after 3 h of reaction, and the removal rates of As(V) and Sb(V) were detected and compared with those in Example 1.

[0078] The specific operation of this comparative example 1 is as follows: 300 mL of the mine wastewater solution of Example 1 (As(V) content: 0.75 mg / L, Sb(V) content: 1.22 mg / L) was added to a 500 mL cylindrical glass electrolytic cell, Pt was inserted as a working electrode, Pt was inserted as a counter electrode, and Ag / AgCl was inserted as a reference electrode to form a three-electrode system electrolytic cell; the reaction temperature of the system was controlled to 35°C using a constant temperature water bath, the three electrodes were connected to an electrochemical workstation, and a multi-potential step mode was used to cycle electrolysis for 6 h at +1 V for 600 s and -0.3 V for 600 s. After the reaction was completed, 3 mL of the sample was sampled through a 0.22 μm needle filter membrane, and the As and Sb in the filtrate were determined by ICP-AES method. The contents were 0.17 mg / L and 0.14 mg / L, respectively, and the removal rates of As(V) and Sb(V) were 77.3% and 88.5%, respectively.

[0079] The removal efficiency of this method is significantly lower than the 99.7% As(V) removal rate and the 99.3% Sb(V) removal rate in Example 1. The applicant speculates that the degree of crystallinity of the Schmidt mineral obtained by the method of Comparative Example 1 is indeed higher, but the better the degree of crystallinity of the mineral, the lower the specific surface area, and the fewer exposed hydroxyl active sites, which is not conducive to the further adsorption and fixation of As and Sb. The present invention focuses on the removal rate of As and Sb. The method of the present invention has a higher mineralization rate, which is conducive to the co-precipitation of As and Sb with Fe. The resulting mineral has poor crystallinity but more hydroxyl active sites, which is conducive to the further adsorption of As and Sb on the surface of the resulting mineral.

[0080] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0081] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for simultaneously removing As(V) and Sb(V) by electrochemical in-situ mineralization, characterized in that: The method comprises the following steps: (1) Place acid mine drainage in a container and insert an anode electrode and a cathode electrode to form a two-electrode electrolytic cell; (2) Under magnetic stirring conditions, the electrochemical reaction is carried out by constant current method, and the generated precipitate is filtered; In step (1), the anode electrode is used to convert Fe 2+ Oxidized to Fe 3+ ; The cathode electrode is used to reduce oxygen to generate OH - ; Wherein, in step (2), the electrochemical reaction selects the chronopotentiometry mode, sets the cathode current to 0 mA, the anode current to 180-220 mA, the cathode time to 0 s, and the anode time to 7200-10800 s; The anode electrode is any one of a RuO2-IrO2 coated titanium-based electrode, a Ta2O5-IrO2 coated titanium-based electrode, a platinum electrode (Pt) or a graphite electrode, and the cathode electrode is any one of a 304 stainless steel electrode or a Pt electrode; The total Fe content in the acid mine drainage water is 200-1000 mg / L; the SO4 2- The content is 1000-3000 mg / L; The As(V) content in the acid mine wastewater is 0.1-100 mg / L; and the Sb(V) content in the acid mine wastewater is 0.1-150 mg / L.

2. The method for simultaneous removal of As(V) and Sb(V) by electrochemical in-situ mineralization according to claim 1, characterized in that: In the step (1), the acid mine drainage water further includes a pre-treatment step, wherein the pre-treatment step is to remove suspended particles in the water body by filtering through a microporous filter membrane.

3. The method for simultaneous removal of As(V) and Sb(V) by electrochemical in-situ mineralization according to claim 1, characterized in that: In the step (1), the anode electrode undergoes an anode pretreatment step, which comprises soaking the anode electrode in a 10%-15% citric acid solution for 20-40 minutes for pickling to remove surface oxides, then rinsing with deionized water, and finally drying with nitrogen.

4. The method for simultaneous removal of As(V) and Sb(V) by electrochemical in-situ mineralization according to claim 1, characterized in that: In the step (1), the cathode electrode undergoes a cathode pretreatment step, which comprises polishing the cathode electrode with 1000-1500 mesh sandpaper to remove the passivation layer, then ultrasonically cleaning the cathode electrode with acetone, ethanol, and deionized water in sequence, and finally drying the cathode electrode with nitrogen.

5. The method for simultaneous removal of As(V) and Sb(V) by electrochemical in-situ mineralization according to any one of claims 1 to 4, characterized in that: In the step (1), the pH value of the acid mine wastewater is 2-4.

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