Method for simultaneously removing As (V) and Sb (V) by electrochemical in-situ mineralization

Abstract

The invention discloses a method for simultaneously removing As (V) and Sb (V) by electrochemical in-situ mineralization, which comprises the following steps of: putting acidic mine wastewater into a container, and inserting an anode electrode and a cathode electrode to form a dual-electrode electrolytic tank; carrying out electrochemical reaction through a constant current method, and filtering the generated precipitate; wherein the anode electrode is used for oxidizing Fe < 2 + > in the acid mine wastewater into Fe < 3 + >; the cathode electrode is used for reducing oxygen to generate OH <->; the electrochemical reaction selects a timing potential mode. According to the method, the Schwertmannite is directly generated in the acid mine wastewater through an electrochemical means, As (V) and Sb (V) are carried in the precipitation process to enter crystal lattices of the Schwertmannite to form coprecipitation, and under the combined action of coprecipitation and adsorption, the As (V) and the Sb (V) in a water phase are jointly removed, the method is remarkable in removal effect, no complex adsorbent preparation process exists, and the method is suitable for industrial production. No exogenous agent is added, and the process is simple.

Description

Technical Field

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

[0002] Arsenic (As) and antimony (Sb) are typical toxic heavy (metalloid) metal pollutants in the same group (Group 15) of the periodic table, with significant biological toxicity and health risks. In aerobic environments such as surface water, the main existing forms of As and Sb are pentavalent arsenic (As(V)) and pentavalent antimony (Sb(V)). As and Sb have similar chemical properties, so they are often associated with sulfide deposits (such as realgar, stibnite, etc.). In mining, smelting and industrial activities, As and Sb widely exist in acid mine drainage (AMD), tailings pond leachate, smelting wastewater and industrial wastewater in the form of combined pollution.

[0003] Due to their environmental coexistence characteristics and the requirement of treatment efficiency for As and Sb in acid mine drainage, the co-removal of As and Sb has attracted extensive attention at home and abroad. The main methods are adsorption method and microbial remediation method. However, most of the existing adsorption methods focused on rely on the addition of external agents or complex adsorbent preparation processes, resulting in increased costs or insufficient engineering adaptability, and the secondary pollution caused by adsorbents needs to be vigilant; although the microbial remediation technology is environmentally friendly, it has strict requirements for the microbial growth environment, a long remediation period, and is not applicable to severely polluted areas (the toxicity of high concentrations of As and Sb inhibits microbial activity). Schwertmannite, as a secondary sulfate iron mineral naturally formed in the acid mine drainage environment, its mineralization process is highly coupled with the acidic environment (pH = 2–4), high Fe(II / III), high SO4 2- concentration and redox conditions in acid mine drainage, and has natural mineral-water interface adaptability and environmental compatibility. Moreover, the unique pore topology structure, exchangeable SO4 2- structure and hydroxyl-rich sites of schwertmannite endow schwertmannite with significant fixing ability for oxyanion pollutants such as As(V) and Sb(V). However, the schwertmannite formed by natural processes such as light and microbial oxidation has problems such as low mineralization rate and uncontrollable mineralization process, which limits its fixing ability for coexisting pollutants.

[0004] Chinese Patent Application CN202010142704.9 discloses a method for rapid synthesis of schwertmannite by electrochemical deposition. The schwertmannite synthesized by this method has the characteristics of high specific surface area, uniform particle size, typically sea urchin-like spherical microscopically, and rich surface whiskers. However, the technical problem solved by this method is how to obtain schwertmannite with better crystallinity, and the fixing effect on As and Sb is not good during the mineral formation process. Summary of the Invention

[0005] Based on this, the present invention provides a method for simultaneously removing As(V) and Sb(V) by in-situ electrochemical mineralization, and the method comprises the following steps: (1) Placing acidic mine wastewater in a container, and inserting an anode electrode and a cathode electrode to form a two-electrode electrolytic cell; (2) Under the condition of magnetic stirring, performing an electrochemical reaction by a constant current method, and filtering the generated precipitate. Among them, in step (1), the anode cell is used to oxidize Fe in the acidic mine wastewater 2+ to Fe 3+ ; the cathode cell is used to reduce oxygen to generate OH - ; Among them, in step (2), the electrochemical reaction selects a 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. More preferably, the anode time is 9000 - 10800 s. Further preferably, the anode current is 190 - 210 mA.

[0006] The principle of the electrochemical reaction of the present invention is: by electrochemical means, adopting the constant current method, promoting the oxidation of Fe(II) in the acidic mine wastewater at the anode, and simultaneously promoting the reduction of oxygen at the cathode to generate OH - ; the increase in pH promotes the hydrolysis reaction of the Fe(III) generated at the anode and the original Fe(III) in the acidic mine wastewater, and generates scorodite under the regulation of SO4 2- ; during the precipitation process, As(V) and Sb(V) are wrapped into the scorodite lattice to form a coprecipitate, and the generated scorodite further fixes the remaining As(V) and Sb(V) in the solution through adsorption. Under the combined action of coprecipitation and adsorption, the simultaneous removal of As(V) and Sb(V) in the aqueous phase is realized, as shown in Figure 1 .

[0007] In the present invention, the scorodite generated by the electrochemical reaction has a unique pore topology structure and an exchangeable state structure SO4 2- , especially the characteristic of rich hydroxyl sites, which endows the scorodite with significant fixation ability for oxygen-containing anion pollutants such as As(V) and Sb(V), and can simultaneously greatly reduce the mobile As(V) and Sb(V) in the wastewater. This method has no complex adsorbent preparation process, and no exogenous agents need to be added. The process is simple and easy to operate.

[0008] In the present invention, the design of rich hydroxyl sites significantly increases the immobilization ability of schwertmannite for As(V) and Sb(V), especially the immobilization and removal effect on Sb(V). More preferably, without the addition of external reagents, As(V) and Sb(V) are co-removed simultaneously while schwertmannite is generated through an electrochemical reaction; in addition, the contents of Fe, SO4 2- and H + in acidic mine wastewater are also reduced, realizing the in-situ purification application of wastewater.

[0009] In step (2) of the present invention, the magnetic stirring rate is preferably 60-100 rpm.

[0010] According to the method for simultaneously removing As(V) and Sb(V) by in-situ mineralization through electrochemistry as described in claim 1, preferably, in step (1), the acidic mine wastewater further includes a pretreatment step, and the pretreatment step is to remove suspended particulate matter in the water body by filtration through a microporous filter membrane.

[0011] According to the method for simultaneously removing As(V) and Sb(V) by in-situ mineralization through electrochemistry as described in claim 1, preferably, in step (1), the anode electrode is a coated titanium-based electrode, a coated titanium-based electrode, a Pt electrode or any one of graphite electrodes, and the cathode electrode is any one of 304 stainless steel electrodes or Pt electrodes. More preferably, the anode electrode is a coated titanium-based electrode, and the cathode electrode is a 304 stainless steel electrode.

[0012] According to the method for simultaneously removing As(V) and Sb(V) by in-situ mineralization through electrochemistry as described in 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 for pickling to remove surface oxides, then rinsing it thoroughly with deionized water, and finally drying it with nitrogen.

[0013] According to the method for simultaneously removing As(V) and Sb(V) by in-situ mineralization through electrochemistry as described in 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 successively with acetone, ethanol, and deionized water, and finally drying it with nitrogen.

[0014] The method for simultaneous in-situ mineralization and removal of As(V) and Sb(V) electrochemically according to claim 1, preferably, in the step (1), the content of As(V) in the acidic mine wastewater is 0.1-100 mg / L. More preferably, as a more preferred embodiment of the present invention, the content of As(V) in the acidic mine wastewater is 2-10 mg / L; further preferably, the content of As(V) in the acidic mine wastewater is 3-8 mg / L.

[0015] The method for simultaneous in-situ mineralization and removal of As(V) and Sb(V) electrochemically according to claim 1, preferably, in the step (1), the content of Sb(V) in the acidic mine wastewater is 0.1-150 mg / L.

[0016] As another embodiment of the present invention, the content of Sb(V) in the acidic mine wastewater is 1-20 mg / L. Using the wastewater with the above content concentration range of Sb(V), the removal rate of Sb(V) reaches more than 99%.

[0017] As a preferred embodiment of the present invention, the content of As(V) in the acidic mine wastewater is 1-15 mg / L, and the content of Sb(V) in the acidic mine wastewater is 1-50 mg / L; as a more preferred embodiment of the present invention, the content of As(V) in the acidic mine wastewater is 2-10 mg / L, and the content of Sb(V) in the acidic mine wastewater is 10-40 mg / L; as a more preferred embodiment of the present invention, the content of As(V) in the acidic mine wastewater is 3-8 mg / L, and the content of Sb(V) in the acidic mine wastewater is 15-35 mg / L. The electrochemical method of the present invention is more suitable for removing the concentration contents of As(V) and Sb(V) in the acidic mine wastewater within the above ranges.

[0018] The method for simultaneous in-situ mineralization and removal of As(V) and Sb(V) electrochemically according to claim 1, preferably, in the step (1), the total content of total Fe in the acidic mine wastewater is 200-1000 mg / L.

[0019] As a preferred embodiment of the present invention, the total content of total Fe in the acidic mine wastewater is 300-1000 mg / L; further preferably, the total content of total Fe in the acidic mine wastewater is 500-800 mg / L.

[0020] The method for simultaneous in-situ mineralization and removal of As(V) and Sb(V) electrochemically according to claim 1, preferably, in the step (1), the SO4 2- content in the acidic mine wastewater is 1000-3000 mg / L.

[0021] As a preferred embodiment of the present invention, the content of SO4 2- in the acid mine wastewater is 1500 - 3000 mg / L; further preferably, the content of SO4 2- in the acid mine wastewater is 2000 - 3000 mg / L.

[0022] As a specific embodiment of the present invention, the content of As(V) in the acid mine wastewater is 1 - 15 mg / L, the content of Sb(V) in the acid mine wastewater is 1 - 50 mg / L, the total content of total Fe in the acid mine wastewater is 300 - 1000 mg / L, and the content of SO4 2- 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 total Fe in the acid mine wastewater is 500 - 800 mg / L, and the content of SO4 2- in the acid mine wastewater is 2000 - 3000 mg / L. Treating the wastewater within the above range can not only effectively remove As(V) and Sb(V), but also reduce the contents of Fe, SO4 2- and H + in the acid mine wastewater, especially the removal effect of SO4 2- is more significant.

[0023] According to the method for simultaneously removing As(V) and Sb(V) by in-situ mineralization electrochemically according to claim 1, preferably, in the step (1), the pH value of the acid mine wastewater is 2 - 4. More preferably, the pH value of the acid mine wastewater is 3 - 4.

[0024] Compared with the prior art, the present invention has the following beneficial effects: The method of the present invention uses electrochemical means, adopts the constant current method, and can generate scorodite in the acid mine wastewater without adding external agents. During the precipitation process, As(V) and Sb(V) are wrapped into the scorodite lattice to form coprecipitation. Moreover, the generated scorodite further fixes the remaining As(V) and Sb(V) in the solution through adsorption. Under the combined action of coprecipitation and adsorption, the simultaneous removal of As(V) and Sb(V) in the aqueous phase is achieved. This method has a significant removal effect, no complex adsorbent preparation process, no addition of external agents, a simple process, and is easy to operate.

[0025] In addition, the method of the present invention also reduces the contents of Fe, SO4 2- and H +Content to achieve in-situ purification of wastewater applications. Brief Description of the Drawings

[0026] Figure 1 This is the working schematic diagram of a method for simultaneously removing As(V) and Sb(V) by in-situ electrochemical mineralization in the present invention.

[0027] Figure 2 This is a method for simultaneously removing As(V) and Sb(V) by in-situ electrochemical mineralization in the present invention. It is a graph showing the change of the main components of the electrolyte with time during the constant current electrochemical reaction in acidic mine wastewater with different As(V) and Sb(V) concentration contents.

[0028] Figure 3 This is a method for simultaneously removing As(V) and Sb(V) by in-situ electrochemical mineralization in the present invention. It is an X-ray diffraction pattern of the solid-phase particles obtained after 3 h of constant current electrochemical reaction in acidic mine wastewater with different As(V) and Sb(V) concentration contents. The symbol marked position is the characteristic peak of scorodite. Detailed Embodiments

[0029] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below in combination 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 understanding of the content of the present invention more thorough and comprehensive.

[0030] Electrode Description

[0031] In the present invention, an MMO anode (i.e., coated titanium-based electrode) and a 304 stainless steel cathode are used, both purchased from Suzhou Shulte Industrial Technology Co., Ltd., and the specifications are both 30 mm × 30 mm. The following methods are used to treat the MMO anode and the 304 stainless steel cathode: Treatment of the MMO anode: First, soak the MMO electrode with a size of 30 mm × 30 mm in a 10% citric acid solution for 30 min for pickling to remove the surface oxide, then rinse it with deionized water, and finally dry it with nitrogen.

[0032] Preparation of the 304 stainless steel cathode: Grind the 304 stainless steel electrode with a size of 30 mm × 30 mm with 1500-mesh sandpaper to remove the passivation layer, then ultrasonically clean it successively with acetone, ethanol, and deionized water, and finally dry it with nitrogen.

[0033] Method for experimentally preparing acidic mine wastewater:

[0034] Preparation of As(V) stock solution: Weigh 2.1196 g of sodium arsenate dodecahydrate (Na3AsO4·12H2O) accurately with an analytical balance (accuracy 0.0001 g), dissolve it in deionized water, and make up the volume to 1 L to obtain an As(V) stock solution with a concentration of 5 mM; Preparation of Sb(V) stock solution: Weigh 1.3146 g of potassium antimonate (KSb(OH)6) accurately with an analytical balance (accuracy 0.0001 g), stir and dissolve it in 500 mL of deionized water at 60 °C. After cooling to room temperature, transfer it to a volumetric flask, wash the beaker with pure water 3 times, combine the washing solutions into the volumetric flask, and make up the volume to 1 L to obtain an Sb(V) stock solution with a concentration of 5 mM; Preparation of acidic mine wastewater: Dissolve 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 in deionized water and make up the volume to 1 L. Adjust the pH of the solution to 3.0 with dilute sulfuric acid and sodium hydroxide to obtain acidic mine wastewater containing different concentrations of As(V) and Sb(V); Adjust the concentrations of As(V) and Sb(V) in the acidic mine wastewater by adjusting the amounts of the added As(V) stock solution and Sb(V) stock solution.

[0035] Content determination method and removal rate calculation method:

[0036] Content determination method of components: Filter the suspension after the electrochemical reaction with a microporous filter membrane to obtain a filtrate and a solid precipitate. Freeze-dry the solid precipitate, and then grind it through a 200-mesh sieve to obtain solid-phase particles.

[0037] Use inductively coupled plasma-atomic emission spectrometry (ICP-AES) to determine the contents of As and Sb elements and the total Fe content in the filtrate; Use ultraviolet-visible spectrophotometry (UV-Vis) to determine the Fe(II) content in the filtrate; Use ion chromatography (IC) to determine the content of SO42- in the filtrate; Use X-ray diffraction spectrometer (XRD) to determine the solid-phase particles and determine the composition of the solid-phase particles.

[0038] The removal rates of As(V) and Sb(V) are obtained through the following formula: Removal rate = (C0 - C t ) / C0 × 100%, where C0 represents the initial As(V) or Sb(V) concentration; C t represents the concentration of As(V) or Sb(V) at time t when the reaction proceeds. Example 1

[0039] A method for in-situ mineralization of electrochemistry to simultaneously remove As(V) and Sb(V) in this example includes the following steps: (1) Add 300 mL of acidic mine wastewater solution containing 0.75 mg / L of As(V) and 1.22 mg / L of Sb(V) into a 500 mL cylindrical glass electrolytic cell. Place a magnetic stirrer in the electrolytic cell and stir at a speed of 80 rpm during the reaction process. Insert a treated MMO anode and a 304 stainless steel cathode into the electrolytic cell; (2) Connect the computer to an electrochemical workstation (CHI 660E, Shanghai Chenhua) and carry out an electrochemical reaction using the constant current method. The specific operation is as follows: 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.

[0040] Take 3 mL of samples through a 0.22 μm needle filter membrane at 0, 5, 10, 30, 60, 90, 120, 150, and 180 min of the electrochemical reaction time, and use UV-Vis, ICP-AES, and IC methods to measure Fe(II), As, Sb, and SO4 2- in the filtrate, and obtain the change rates of the contents of the four substances in the solution over time, as Figure 2 shown.

[0041] After the reaction is completed, filter the generated suspension through a 0.22 μm filter membrane, freeze-dry the obtained solid precipitate for 48 h, then grind it and pass it through a 200-mesh sieve, and use XRD to detect the solid phase composition. The XRD results are as Figure 3 shown, which conform to the characteristics of scorodite.

[0042] Removal efficiency of As(V) and Sb(V): After 3 h of reaction, the contents of As and Sb in the solution are 0.002 mg / L and 0.009 mg / L respectively; the removal rate of As(V) is: (0.75 - 0.002) / 0.75×100% = 99.7%, and the removal rate of Sb(V) is: (1.22 - 0.009) / 1.22×100% = 99.3%. Example 2

[0043] A method for in-situ mineralization of electrochemistry to simultaneously remove As(V) and Sb(V) in this example includes the following steps: (1) Add 300 mL of acidic mine wastewater solution containing 7.5 mg / L of As(V) and 12.2 mg / L of Sb(V) into a 500 mL cylindrical glass electrolytic cell. Place a magnetic stir bar in the electrolytic cell and stir at a speed of 80 rpm during the reaction process. Insert the treated MMO anode and 304 stainless steel cathode into the electrolytic cell. (2) Connect the computer to an electrochemical workstation (CHI 660E, Shanghai Chenhua) and perform an electrochemical reaction using the constant current method. The specific operation is as follows: 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.

[0044] Take 3 mL samples through a 0.22 μm needle filter membrane at 0, 5, 10, 30, 60, 90, 120, 150, and 180 min during the electrochemical reaction time, and use UV-Vis, ICP-AES, and IC methods to measure the contents of Fe(II), As, Sb, and SO4 2- in the filtrate, and obtain the change rates of the contents of the four substances in the solution with time, as Figure 2 shown.

[0045] After the reaction is completed, filter the generated suspension through a 0.22 μm filter membrane, freeze-dry the obtained solid precipitate for 48 h, then grind it and pass it through a 200-mesh sieve, and use XRD to detect the solid phase composition. The XRD results are as Figure 3 shown, which conform to the characteristics of scorodite.

[0046] Removal efficiency of As(V) and Sb(V): After 3 h of reaction, the contents of As and Sb in the solution are 0.019 mg / L and 0.083 mg / L, respectively; the removal rate of As(V) is: (7.5 - 0.029) / 7.5 × 100% = 99.6%, and the removal rate of Sb(V) is: (12.2 - 0.043) / 12.2 × 100% = 99.6%. Example 3

[0047] A method for in-situ mineralization by electrochemistry to simultaneously remove As(V) and Sb(V) in this example includes the following steps: (1) Add 300 mL of acidic mine wastewater solution containing 75 mg / L of As(V) and 122 mg / L of Sb(V) into a 500 mL cylindrical glass electrolytic cell. Place a magnetic stir bar in the electrolytic cell and stir at a speed of 80 rpm during the reaction process. Insert the treated MMO anode and 304 stainless steel cathode into the electrolytic cell. (2) Connect the computer to an electrochemical workstation (CHI 660E, Shanghai Chenhua), and conduct an electrochemical reaction using the constant current method. The specific operation is as follows: 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.

[0048] At 0, 5, 10, 30, 60, 90, 120, 150, and 180 min during the electrochemical reaction time, take 3 mL of samples through a 0.22 μm needle filter membrane respectively, and use UV-Vis, ICP-AES, and IC methods to measure the contents of Fe(II), As and Sb, and SO42- in the filtrate, and obtain the change rates of the contents of the four substances in the solution over time, as Figure 2 shown.

[0049] After the reaction is completed, filter the generated suspension through a 0.22 μm filter membrane, freeze-dry the obtained solid precipitate for 48 h, then grind and pass through a 200-mesh sieve, and use XRD to detect the solid phase composition. The XRD results are as Figure 3 shown, which conform to the characteristics of scorodite.

[0050] Removal efficiency of As(V) and Sb(V): After 3 h of reaction, the contents of As and Sb in the solution are 2.87 mg / L and 2.81 mg / L respectively; the removal rate of As(V) is: (75 - 2.87) / 75×100% = 96.2%, and the removal rate of Sb(V) is: (122 - 2.81) / 122×100% = 97.7%. Example 4

[0051] A method for in-situ electrochemical mineralization to simultaneously remove As(V) and Sb(V) in this example is the same as that in Example 1 in other steps except for the different acidic mine wastewater used. In this example, the acidic mine wastewater is obtained by filtering the surface runoff downstream of the Xikuangshan mining area in Hunan through a 0.22 μm filter membrane, and the main component contents are shown in Table 1.

[0052] After 3 h of reaction, the contents of As and Sb in the filtrate are 0.12 mg / L and 1.17 mg / L respectively, and the removal rates of As(V) and Sb(V) are 97.4% and 95.9% respectively.

[0053] Table 1 Water quality characteristics of acidic mine wastewater in Example 4 Main parameters Value 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 Comparative Example 1 Use the electrochemical method described in Chinese Patent Application CN202010142704.9 to treat the acidic mine wastewater in Example 1, and detect the contents of As and Sb in the filtrate and the removal rates of As(V) and Sb(V) after 3 h of reaction, and compare with Example 1.

[0054] The specific operation of this Comparative Example 1 was as follows: 300 mL of the mine wastewater solution of Example 1 (with As(V) content of 0.75 mg / L and Sb(V) content of 1.22 mg / L) was added to a 500 mL cylindrical glass electrolytic cell. A Pt working electrode, a Pt counter electrode, and an Ag / AgCl reference electrode were inserted to form a three-electrode system electrolytic cell. The reaction temperature of the system was controlled at 35 °C using a constant temperature water bath. The three electrodes were connected to an electrochemical workstation, and a multi-potential step mode was adopted. The electrolysis was carried out in a cycle of +1V for 600 s and -0.3V for 600 s for 6 h. After the reaction, 3 mL of the sample was taken through a 0.22 μm needle filter membrane, and the contents of As and Sb in the filtrate were measured 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.

[0055] The removal efficiency of this method was significantly lower than the removal rate of As(V) of 99.7% and the removal rate of Sb(V) of 99.3% in Example 1. The applicant speculated that the schwertmannite obtained by the method of Comparative Example 1 did have a higher degree of crystallization. However, the better the degree of mineral crystallization, the lower the specific surface area and the fewer the exposed hydroxyl active sites, which was not conducive to the further adsorption and fixation of As and Sb. The present invention focuses on the removal rates of As and Sb. Using the method of the present invention, the mineralization rate is higher, which is conducive to the coprecipitation of As and Sb with Fe. The generated mineral has a poor crystallinity but more hydroxyl active sites, which is conducive to the further adsorption of As and Sb on the surface of the generated mineral.

[0056] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0057] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be subject to the appended claims.

Claims

1. A method for simultaneously removing As(V) and Sb(V) by in-situ electrochemical mineralization, characterized in that, The method includes the following steps: (1) Place the acid mine wastewater in a container, and insert an anode electrode and a cathode electrode to form a two-electrode electrolytic cell; (2) Under the condition of magnetic stirring, carry out an electrochemical reaction by the constant current method, and filter the generated precipitate; Among them, in step (1), the anode electrode is used to oxidize Fe in acidic mine wastewater 2+ to Fe 3+ ; the cathode electrode is used to reduce oxygen to generate OH - ; Among them, in step (2), the electrochemical reaction selects the chronopotentiometry mode, and the cathode current is set to 0 mA, the anode current is 180 - 220 mA, the cathode time is 0 s, and the anode time is 7200 - 10800 s.

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 step (1), the acid mine wastewater further includes a pretreatment step, and the pretreatment step is to filter and remove suspended particulate matter in the water body through a microporous filter membrane.

3. The method for simultaneously removing As(V) and Sb(V) by in-situ mineralization electrochemically according to claim 1, characterized in that, In the step (1), the anode electrode is a coated titanium-based electrode, a coated titanium-based electrode, a platinum electrode (Pt), or any one of graphite electrodes, and the cathode electrode is any one of 304 stainless steel electrodes or Pt electrodes.

4. The method for simultaneously removing As(V) and Sb(V) by in-situ mineralization electrochemically according to claim 3, characterized in that, In step (1), the anode electrode undergoes an anode pretreatment step, and the anode pretreatment step is: soak the anode electrode in a 10% - 15% citric acid solution for 20 - 40 min for pickling to remove surface oxides, then rinse it with deionized water until clean, and finally dry it with nitrogen.

5. The method for simultaneously removing As(V) and Sb(V) by in-situ mineralization in an electrochemical cell according to claim 3, wherein, In step (1), the cathode electrode undergoes a cathode pretreatment step, and the cathode pretreatment step is: polish the cathode electrode with 1000 - 1500 - mesh sandpaper to remove the passivation layer, then ultrasonically clean it successively with acetone, ethanol, and deionized water, and finally dry it with nitrogen.

6. The method for simultaneously removing As(V) and Sb(V) by in-situ mineralization in an electrochemical cell according to any one of claims 1-5, characterized in that, In step (1), the content of As(V) in the acid mine wastewater is 0.1 - 100 mg / L.

7. The method for simultaneous removal of As(V) and Sb(V) by electrochemical in-situ mineralization according to any one of claims 1 to 5, characterized in that: In step (1), the content of Sb(V) in the acid mine wastewater is 0.1 - 150 mg / L.

8. The method for simultaneously removing As(V) and Sb(V) by in-situ mineralization electrochemically according to any one of claims 1-5, characterized in that, In step (1), the content of total Fe in the acid mine wastewater is 200 - 1000 mg / L.

9. The method for simultaneously removing As(V) and Sb(V) by in-situ mineralization electrochemically according to any one of claims 1-5, characterized in that, In the step (1), the content of SO4 2- in the acid mine wastewater is 1000 - 3000 mg / L.

10. The method for in-situ electrochemically forming minerals and simultaneously removing As(V) and Sb(V) according to any one of claims 1-5, characterized in that, In step (1), the pH value of the acid mine wastewater is 2 - 4.

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