Method for treating electrolytic manganese wastewater by using carbon-based electrode and application of method

Abstract

The invention relates to a method for treating electrolytic manganese wastewater by using a carbon-based electrode and application of the method. The method comprises the following steps: respectively loading the electrolytic manganese wastewater into a double-chamber electrolytic bath, reducing, settling and recycling manganese ions at a cathode, oxidizing and recycling the manganese ions at an anode, and oxidizing and removing ammonia nitrogen at the same time; finally, manganese ions are recovered in the form of oxide, and ammonia nitrogen is removed in the form of nitrogen. The method is simple to operate, can effectively reduce the concentration of manganese ions and ammonia nitrogen in the electrolytic manganese wastewater, and has great significance for improving the ecological environment; and the double-chamber electrolytic bath is utilized, so that the ammonia nitrogen is removed, meanwhile, the manganese is recycled, and the treatment cost of the wastewater can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, in particular to a method for treating electrolytic manganese wastewater by using a carbon-based electrode and application thereof. Background Art

[0002] In 2022, China's manganese ore reserves will reach 280 million tons, accounting for 16.5% of the world's total, and its reserves rank second in the world. my country's electrolytic manganese production accounts for 98% of the world's electrolytic manganese production, making it the world's largest electrolytic manganese producer.

[0003] The rapid development of the electrolytic manganese industry can promote economic growth, but it also causes serious environmental pollution. The main manifestation is that the wastewater produced by electrolytic manganese contains substances that threaten human health and the ecological environment, and has a high content of suspended matter and significant color. According to the survey, in the manganese-containing wastewater produced by electrolytic manganese metal production enterprises, Mn 2+ The concentration is usually as high as 10-15g / L, or even higher. At present, the main methods for treating manganese-containing wastewater are precipitation, oxidation, biological and electrolytic methods. Among them: precipitation is to use flocculants to precipitate pollutants in electrolytic manganese wastewater. The operation is simple, but it produces a large amount of sludge that is difficult to handle; biological method is a treatment method that uses microorganisms to convert pollutants in electrolytic manganese wastewater into harmless substances. The treatment effect is good, but the technical requirements are high; oxidation is a method of using strong oxidants to oxidize and decompose pollutants in wastewater to purify wastewater, but oxidants are difficult to store and transport, and are easy to interfere with operations; and electrolytic method has the advantages of fast processing speed and easy control.

[0004] The concentration of ammonia nitrogen in the wastewater produced by electrolytic manganese is relatively high. Traditional methods for removing ammonia nitrogen include biological methods, gas stripping methods, breakpoint chlorination methods, chemical precipitation methods (such as struvite) and ion exchange methods, depending on the nitrogen concentration. Among them: when the ammonia concentration is in the range of tens to hundreds of mg / L, the biological method is the most effective. However, due to the tolerance level of microorganisms, when the ammonia nitrogen concentration is at a higher level, the treatment effect of this method is poor; for wastewater with ammonia concentrations as high as thousands or even tens of thousands of mg / L, the gas stripping method can transfer ammonia from the liquid phase to the gas phase to achieve ammonia recovery, but it has the disadvantage of poor economic efficiency when used to treat low-concentration ammonia; the ion exchange method has the disadvantages of limited exchange capacity, easy to cause secondary pollution, and complex regeneration process, which is not suitable for large-scale industrial applications; the cost of the reagents used in the breakpoint chlorination method is too high, and the additional alkali generated during the treatment process needs to be neutralized, thereby increasing the content of total dissolved solids. At the same time, the by-products such as chloramines and chlorinated organic matter will also cause secondary pollution; the chemical precipitation method is still in the laboratory stage, and the actual application needs further development.

[0005] At present, there are almost no special facilities for treating ammonia nitrogen in wastewater in my country's electrolytic manganese enterprises, and most of them discharge directly, so measures need to be taken to control ammonia nitrogen wastewater. In recent years, electrochemical advanced oxidation technology (EAOP) has been widely used in water environment remediation and has shown great potential in treating ammonia nitrogen wastewater. Research on electrochemical technology for electrolytic manganese wastewater is of great significance for the efficient, green and harmless treatment of electrolytic manganese wastewater. Summary of the invention

[0006] The invention discloses a method for treating electrolytic manganese wastewater by using a carbon-based electrode and application thereof, which can effectively reduce the concentration of manganese ions and ammonia nitrogen in the electrolytic manganese wastewater and is of great significance for improving the ecological environment.

[0007] To achieve the above object, the technical solution of the present invention is: A method for treating electrolytic manganese wastewater using a carbon-based electrode comprises the following steps: (1) subjecting the carbon-based material to oxidation treatment to obtain an oxidized carbon-based material; (2) The oxidized carbon-based material is used as an anode and a cheap conductive material is used as a cathode, and electrolytic manganese wastewater is introduced into a double-chamber electrolytic cell for electrolytic treatment.

[0008] Preferably, in step (1), the carbon-based material is one of graphite sheet, graphite felt and carbon cloth; In step (2), the cathode is a graphite sheet or a metal mesh.

[0009] Preferably, the metal mesh is one of a nickel mesh, a copper mesh and an iron mesh.

[0010] Preferably, in step (1), the oxidation treatment of the carbon-based material specifically includes: S1. Add carbon-based materials to 6-9% volume fraction hydrochloric acid and heat at 120-140 °C for 8-14 h; S2. Cleaning the carbon-based material after treatment in step S1 and drying; S3. Add the carbon-based material treated in step S3 to 4.5-5.5 mol / L HNO 3 Solution, heated at 120~140℃ for 8~14 h; S4. The carbon-based material treated in step S3 is washed to neutrality and dried to obtain an oxidized carbon-based material.

[0011] Preferably, the anode and the cathode have the same area, the distance between the anode and the cathode is 5 to 15 cm, and they are separated by an ion exchange membrane.

[0012] Preferably, in step (2), the operating voltage in the double-chamber electrolyzer is 1.0-2.6 V, the electrolysis time is 8-40 h, or the current density is 5-30 mA / cm 2 , the electrolysis time is 8~40 h.

[0013] Preferably, the electrolysis method is constant voltage electrolysis, constant current electrolysis, step-by-step multi-voltage electrolysis or step-by-step multi-current electrolysis, and the time for replacing the anode during the electrolysis process does not exceed 10 h.

[0014] Preferably, the electrolysis method is constant voltage electrolysis, and the working voltage in the double-chamber electrolytic cell is 1.2 V; Or the electrolysis method is step-by-step multi-voltage electrolysis, and the steps of step-by-step multi-voltage electrolysis are: working voltage is 1.0 V, electrolysis time is 2 to 4 h, working voltage is 1.1 V, electrolysis time is 2 to 4 h, working voltage is 1.2 V, and electrolysis is performed until the electrolytic manganese wastewater treatment is completed.

[0015] Preferably, in step (2), the pH value of the electrolytic manganese wastewater is 6-9, or is pretreated to a pH value of 6-9.

[0016] The present invention also provides application of the above method in reducing the concentration of manganese ions and ammonia nitrogen in electrolytic manganese wastewater.

[0017] The present invention has the following advantages: (1) The present invention uses electrochemical technology to treat electrolytic manganese wastewater. After electrolysis, manganese ions are converted into MnO 2 , Mn 3 O 4 It can be recovered in the form of nitrogen gas, and ammonia nitrogen can be removed in the form of nitrogen gas, which can effectively realize the efficient, green and harmless treatment of electrolytic manganese wastewater.

[0018] (2) The present invention uses an oxidized carbon-based material as the anode. The carbon-based material has stable chemical properties and is resistant to corrosion by acids, alkalis and organic solvents at room temperature. It is generally not easy to undergo redox reactions. It also has a wide electrochemical window and a low background current. It also has the advantage of low cost and is an ideal material for treating electrolytic manganese wastewater.

[0019] (3) The concentration of ammonia nitrogen in electrolytic manganese wastewater is generally 2~10 g / L. Choosing electrochemical technology to treat electrolytic manganese wastewater can solve the problem of microbial intolerance in biological methods to reduce ammonia nitrogen concentration, as well as the problem of poor economic efficiency of gas stripping methods to reduce ammonia nitrogen concentration.

[0020] (4) The present invention isolates manganese mine wastewater with a proton exchange membrane, reduces and precipitates manganese ions at the cathode for recovery, oxidizes and recovers manganese ions at the anode, and simultaneously oxidizes and removes ammonia nitrogen. There is no need to add other oxidants to remove ammonia nitrogen, thereby effectively reducing the treatment cost.

[0021] (5) The method of the present invention has simple steps, is easy to operate, cheap and efficient, and is suitable for large-scale industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the standard curve for determining manganese ion concentration using potassium periodate oxidation method.

[0023] Figure 2 This is the standard curve for determining ammonia nitrogen concentration using the Nessler colorimetric method.

[0024] Figure 3 The anode product MnO of Example 2 2 XRD pattern of .

[0025] Figure 4 Mn is the cathode product of Example 2 3 O 4 XRD pattern of .

[0026] Figure 5 The anode product MnO of Example 3 2 XRD pattern of .

[0027] Figure 6 is the cathode product Mn of Example 3 3 O 4 XRD pattern of .

[0028] Figure 7 The cathode product MnO of Example 3 2 XRD pattern of .

[0029] Figure 8 The anode product MnO of Example 4 2 XRD pattern of .

[0030] Fig. 9 The cathode product MnO of Example 4 2 XRD pattern of .

[0031] Fig.10 The cathode product Mn(OH) of Example 4 2 XRD pattern of .

[0032] Fig.11 The anode product MnO of Example 5 2 XRD pattern of .

[0033] Fig.12The cathode product MnO of Example 5 2 XRD pattern of . DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the following embodiments.

[0035] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0036] A method for treating electrolytic manganese wastewater using a carbon-based electrode comprises the following steps: (1) subjecting the carbon-based material to oxidation treatment to obtain an oxidized carbon-based material; (2) The oxidized carbon-based material is used as an anode and a cheap conductive material is used as a cathode, and electrolytic manganese wastewater is introduced into a double-chamber electrolytic cell for electrolytic treatment.

[0037] In some preferred embodiments of the present invention, in step (1), the carbon-based material is one of graphite plate, graphite felt and carbon cloth; In step (2), the cathode is a graphite plate or a metal mesh.

[0038] In some preferred embodiments of the present invention, the metal mesh is one of a nickel mesh, a copper mesh and an iron mesh.

[0039] In some preferred embodiments of the present invention, in step (1), the oxidation treatment of the carbon-based material specifically comprises: S1. Add carbon-based materials to hydrochloric acid with a volume fraction of 6-9% (e.g. 6%, 6.2%, 7%, 7.4%, 8%, 8.4% or 9%) at 120-140 °C (e.g. 120 ℃、125 ℃、130 ℃、135 ℃ or 140 ℃) for 8 to 14 h (e.g. 8 h, 10 h, 11 h, 13 h or 14 h); S2. Cleaning the carbon-based material after treatment in step S1 and drying; S3. Add the carbon-based material treated in step S3 to 4.5-5.5 mol / L HNO 3 Solution, at 120~140 ℃ (e.g. 120 ℃、125 ℃、130 ℃、135 ℃ or 140 ℃) for 8 to 14 h (e.g. 8 h, 10 h, 11 h, 13 h or 14 h); S4. The carbon-based material treated in step S3 is washed to neutrality and dried to obtain an oxidized carbon-based material.

[0040] The above oxidation treatment is mainly to perform surface oxidation treatment on the carbon-based material.

[0041] In some preferred embodiments of the present invention, in step S2 and step S4, the drying method can be adopted, at 120-150 ℃ (e.g. 120 ℃、125 ℃、130 ℃、140 ℃ or 150 ℃) for 6 to 12 h (e.g., 6 h, 8 h, 10 h, 11 h or 12 h).

[0042] In some preferred embodiments of the present invention, the anode and the cathode have equal areas, the plate spacing between the anode and the cathode is 5 to 15 cm (e.g., 5 cm, 7 cm, 8 cm, 9 cm, 12 cm or 15 cm), and are separated by an ion exchange membrane.

[0043] In some preferred embodiments of the present invention, in step (2), the operating voltage of the dual-chamber electrolyzer is 1.0-2.6 V (e.g., 1.0 V, 1.1 V, 1.2 V, 1.3 V, 1.6 V, 2.0 V or 2.6 V), the electrolysis time is 8-40 h (e.g., 8 h, 10 h, 11 h, 16 h, 20 h, 25 h, 30 h, 35 h or 40 h), or the current density is 5-30 mA / cm 2 The electrolysis time is 8 to 40 h (such as 8 h, 10 h, 11 h, 16 h, 20 h, 25 h, 30 h, 35 h or 40 h).

[0044] In some preferred embodiments of the present invention, the electrolysis method is constant voltage electrolysis, constant current electrolysis, step-by-step multi-voltage electrolysis or step-by-step multi-current electrolysis, and the time for replacing the anode during the electrolysis process does not exceed 10 hours. During the electrolysis process, manganese ions are deposited on the anode in the form of oxides. In order to ensure the electrolysis effect, it is necessary to replace the anode once in a certain period of time. The time for replacing the anode is, for example, 2 hours, 4 hours, 6 hours, 8 hours or 10 hours. The anode can be replaced once or more as needed during one electrolysis process.

[0045] In some preferred embodiments of the present invention, the electrolysis method is constant voltage electrolysis, and the working voltage of the double-chamber electrolytic cell is 1.2 V; Or the electrolysis method is step-by-step multi-voltage electrolysis, and the steps of step-by-step multi-voltage electrolysis are: the working voltage is 1.0 V, the electrolysis time is 2 to 4 h (for example, 2 h, 3 h or 4 h), the working voltage is 1.1 V, the electrolysis time is 2 to 4 h (for example, 2 h, 3 h or 4 h), the working voltage is 1.2 V, and the electrolysis is performed until the electrolytic manganese wastewater treatment is completed.

[0046] Preferably, in step (2), the pH value of the electrolytic manganese wastewater is 6 to 9 (e.g., 6, 7, 7.5, 8 or 9), or is pretreated to a pH value of 6 to 9 (e.g., 6, 7, 7.5, 8 or 9).

[0047] The present invention also provides application of the above method in reducing the concentration of manganese ions and ammonia nitrogen in electrolytic manganese wastewater.

[0048] The present invention will be further described below by way of examples, but the protection scope of the present invention is not limited to these embodiments.

[0049] In the following examples, the concentrations of manganese ions and ammonia nitrogen in wastewater were determined by potassium periodate oxidation method and Nessler colorimetry, respectively. The corresponding standard curves are shown in Table 1. Figure 1 and Figure 2 shown. Example 1

[0050] The electrolytic manganese ore wastewater was selected to contain high concentrations of manganese ions and ammonia nitrogen. The manganese ion concentration of the wastewater was 5473 mg / L, the ammonia nitrogen concentration was 3145 mg / L, the pH value was 7, the plate spacing was 9 cm, and the volume of the double-chamber electrolytic cell was 70 mL.

[0051] The specific steps are: (1) Place the carbon cloth (2*2 cm 2 ) for oxidation treatment to obtain oxidized carbon cloth, specifically comprising: S1. adding carbon cloth to 200 mL of 6.2% hydrochloric acid [HCl (37%): water = 1:5 (v:v)], and heating at 140 ° C for 12 h; S2. washing the carbon cloth treated in step S1, and drying at 120 ° C for 10 h; S3. adding the carbon cloth treated in step S3 to 200 mL of 5.0 mol / L HNO 3 The solution is heated at 140°C for 12 h; S4. The carbon cloth treated in step S3 is washed to neutrality and dried at 120°C for 10 h to obtain oxidized carbon cloth.

[0052] (2) Use oxidized carbon cloth (2*2cm 2 ) is the anode, nickel mesh (2*2cm 2 ) was used as the cathode, and the working voltage was first set to 1 V, and electrolysis was performed for 2 h. The working voltage was then changed to 1.1 V. After electrolysis for 2 h, the working voltage was changed to 1.2 V. After electrolysis for 2 h, the carbon cloth was replaced, and electrolysis was continued for 5 h. The reaction was completed, and the total electrolysis time was 11 h.

[0053] After treatment, the manganese ion content in the electrolytic manganese ore wastewater in the anode room was 862 mg / L, the degradation rate was 84.2%, the ammonia nitrogen content was 1901 mg / L, and the removal rate was 39.6%; the manganese ion content in the cathode electrolytic manganese ore wastewater was 3116 mg / L, the degradation rate was 43.0%, the ammonia nitrogen content was 2876 mg / L, and the degradation rate was 8.5%.

[0054] The used carbon cloth was soaked in a certain amount of deionized water and squeezed to make it soft, and then ultrasonicated in deionized water. After the ultrasonication, the carbon cloth was cleaned and dried for the next use. 2 The aqueous solution of the sediment is filtered and dried, and the anode sediment is collected. During the electrolysis process, the cathode nickel mesh does not need to be replaced. After use, the sediment is removed by ultrasound. After the ultrasound is completed, the nickel mesh is cleaned and dried for the next use. The aqueous solution of the sediment containing manganese is filtered and dried, and the cathode sediment is collected. Example 2

[0055] The electrolytic manganese ore wastewater was selected to contain high concentrations of manganese ions and ammonia nitrogen. The manganese ion concentration of the wastewater was 5473 mg / L, the ammonia nitrogen concentration was 3145 mg / L, the pH value was 7, the plate spacing was 9 cm, and the volume of the double-chamber electrolytic cell was 80 mL.

[0056] The specific steps are: (1) Place the carbon cloth (2*2 cm 2 ) for oxidation treatment to obtain oxidized carbon cloth, specifically comprising: S1. adding carbon cloth to 200 mL of 7.4% hydrochloric acid [HCl (37%): water = 1:4 (v:v)], and heating at 120 ° C for 14 h; S2. washing the carbon cloth treated in step S1, and drying at 130 ° C for 9 h; S3. adding the carbon cloth treated in step S3 to 200 mL of 5.5 mol / L HNO 3 The solution is heated at 120°C for 14 h; S4. The carbon cloth treated in step S3 is washed to neutrality and dried at 130°C for 9 h to obtain oxidized carbon cloth.

[0057] (2) Use oxidized carbon cloth (2*2cm 2 ) is the anode, nickel mesh (2*2cm2 ) was used as the cathode. The working voltage was first set to 1 V and the electrolysis was performed for 4 h. The working voltage was then changed to 1.1 V. After 2 h of electrolysis, the carbon cloth was replaced. The electrolysis was continued for 2 h. The working voltage was then changed to 1.2 V. After 2 h of electrolysis, the carbon cloth was replaced. The electrolysis was continued for 6 h. The reaction was completed and the electrolysis time was 16 h in total.

[0058] After treatment, the manganese ion content in the electrolytic manganese ore wastewater in the anode chamber was 333 mg / L, the degradation rate was 93.9%, the ammonia nitrogen content was 1935 mg / L, and the removal rate was 38.5%; the manganese ion content in the electrolytic manganese ore wastewater in the cathode chamber was 2758 mg / L, the degradation rate was 49.6%, the ammonia nitrogen content was 2735 mg / L, and the removal rate was 13%.

[0059] The electrode post-treatment steps are the same as in Example 1. The XRD results of the anode deposit are as follows: Figure 3 The cathode deposit XRD results are shown in Figure 4 As shown. The anode product is MnO 2 , the cathode product is Mn 3 O 4 . Example 3

[0060] The electrolytic manganese ore wastewater was selected to contain high concentrations of manganese ions and ammonia nitrogen. The manganese ion concentration of the wastewater was 5627 mg / L, the ammonia nitrogen concentration was 3932 mg / L, the pH value was 7, the plate spacing was 8 cm, and the volume of the double-chamber electrolytic cell was 80 mL.

[0061] The specific steps are: (1) Place the carbon cloth (2*2 cm 2 ) for oxidation treatment to obtain oxidized carbon cloth, specifically comprising: S1. adding carbon cloth to 200 mL of 6.2% hydrochloric acid [HCl (37%): water = 1:5 (v:v)], and heating at 140 ° C for 12 h; S2. washing the carbon cloth treated in step S1, and drying it at 120 ° C for 10 h; S3. adding the carbon cloth treated in step S3 to 200 mL of 5.0 mol / L HNO 3 The solution is heated at 140°C for 12 h; S4. The carbon cloth treated in step S3 is washed to neutrality and dried at 120°C for 10 h to obtain oxidized carbon cloth.

[0062] (2) Use oxidized carbon cloth (2*2cm 2 ) is the anode, nickel mesh (2*2cm 2 ) was used as the cathode, the working voltage was set to 1.2 V, and the electrolysis was performed for 16 h, during which the carbon cloth was replaced after 4 h and 10 h of the total electrolysis time, respectively.

[0063] After treatment, the manganese ion content in the electrolytic manganese ore wastewater in the anode chamber was 418 mg / L, the degradation rate was 92.6%, the ammonia nitrogen content was 1467 mg / L, and the removal rate was 62.7%; the manganese ion content in the electrolytic manganese ore wastewater in the cathode chamber was 3424 mg / L, the degradation rate was 39.2%, the ammonia nitrogen content was 2958 mg / L, and the removal rate was 24.8%.

[0064] The electrode post-treatment steps are the same as in Example 1. The XRD results of the anode deposit are as follows: Figure 5 The cathode deposit XRD results are shown in Figure 6 and Figure 7 shown.

[0065] The anode product was detected to be MnO 2 , the cathode products are Mn 3 O 4 、MnO 2 .

[0066] anode: 2H 2 O-4e - →O 2 +4H + Mn 2+ +2H 2 O-2e - →MnO 2 +4H + cathode: 2H 2 O+2e - →H 2 +2OH - Mn 2+ +2OH - →Mn(OH) 2 Mn(OH) 2 +O 2 →Mn 3 O 4 +6H 2 O 2Mn(OH) 2 +O 2 →2MnO 2 +2H 2 O Example 4

[0067] The electrolytic manganese ore wastewater was selected to contain high concentrations of manganese ions and ammonia nitrogen. The manganese ion concentration of the wastewater was 5712 mg / L, the ammonia nitrogen concentration was 3863 mg / L, the pH value was 7, the plate spacing was 9 cm, and the volume of the double-chamber electrolytic cell was 80 mL.

[0068] The specific steps are: (1) Place the carbon cloth (2*2 cm 2 ) for oxidation treatment to obtain oxidized carbon cloth, specifically comprising: S1. adding carbon cloth to 200 mL of 6.2% hydrochloric acid [HCl (37%): water = 1:5 (v:v)], and heating at 140 ° C for 12 h; S2. washing the carbon cloth treated in step S1, and drying it at 120 ° C for 10 h; S3. adding the carbon cloth treated in step S3 to 200 mL of 5.0 mol / L HNO 3 The solution is heated at 140°C for 12 h; S4. The carbon cloth treated in step S3 is washed to neutrality and dried at 120°C for 10 h to obtain oxidized carbon cloth.

[0069] (2) Use oxidized carbon cloth (2*2cm 2 ) is the anode, nickel mesh (2*2cm 2 ) as the cathode, and the operating current was set to 20 mA cm -2 , electrolysis for 16 h, during which the carbon cloth was replaced after 4 h and 10 h of total electrolysis time, respectively.

[0070] After treatment, the manganese ion content in the electrolytic manganese ore wastewater in the anode chamber was 897 mg / L, the degradation rate was 84.3%, the ammonia nitrogen content was 2206 mg / L, and the removal rate was 42.9%; the manganese ion content in the electrolytic manganese ore wastewater in the cathode chamber was 2809 mg / L, the degradation rate was 50.8%, the ammonia nitrogen content was 3380 mg / L, and the removal rate was 12.5%.

[0071] The electrode post-treatment steps are the same as in Example 1. The XRD results of the anode deposit are as follows: Figure 8 The cathode deposit XRD results are shown in Fig. 9 and Fig.10 shown.

[0072] The working electrode product was detected to be MnO 2 , the products of the counter electrode are Mn(OH) 2 、MnO 2 . Example 5

[0073] The electrolytic manganese ore wastewater was selected to contain high concentrations of manganese ions and ammonia nitrogen. The manganese ion concentration of the wastewater was 7249 mg / L, the ammonia nitrogen concentration was 3697 mg / L, the pH value was 7, the plate spacing was 9 cm, and the volume of the double-chamber electrolytic cell was 80 mL.

[0074] The specific steps are: (1) Place the carbon cloth (2*2 cm 2 ) to obtain an oxidized carbon cloth, specifically comprising: S1. adding carbon cloth to 200 mL of 6% hydrochloric acid by volume, and heating at 140°C for 14 h; S2. washing the carbon cloth treated in step S1, and drying at 140°C for 10 h; S3. adding the carbon cloth treated in step S3 to 200 mL of 4.5 mol / L HNO 3 The solution is heated at 140°C for 14 h; S4. The carbon cloth treated in step S3 is washed to neutrality and dried at 140°C for 10 h to obtain oxidized carbon cloth.

[0075] (2) Use oxidized carbon cloth (2*2cm 2 ) is the anode, nickel mesh (2*2cm 2 ) as cathode, and set the working current to 10 mA cm -2 , constant current electrolysis for 16 h, during which the carbon cloth was replaced after 4 h and 10 h of total electrolysis time, respectively.

[0076] After treatment, the manganese ion content in the electrolytic manganese ore wastewater in the anode chamber was 1699 mg / L, the degradation rate was 76.6%, the ammonia nitrogen content was 2089 mg / L, and the removal rate was 43.5%; the manganese ion content in the electrolytic manganese ore wastewater in the cathode chamber was 3065 mg / L, the degradation rate was 57.7%, the ammonia nitrogen content was 3517 mg / L, and the removal rate was 4.9%.

[0077] Electrode post-treatment step Example 1. Anode deposit XRD results are as follows Fig.11 The cathode deposit XRD results are shown in Fig.12 As shown. Both the anode deposit and the cathode deposit are MnO 2 . Example 6

[0078] The electrolytic manganese ore wastewater was selected to contain high concentrations of manganese ions and ammonia nitrogen. The manganese ion concentration of the wastewater was 7249 mg / L, the ammonia nitrogen concentration was 3697 mg / L, the pH value was 7, the plate spacing was 9 cm, and the volume of the double-chamber electrolytic cell was 80 mL.

[0079] The specific steps are: (1) Place a graphite sheet (0.3 cm * 2*2 cm 2) to obtain an oxidized graphite sheet, specifically comprising: S1. adding a graphite sheet to 200 mL of 6% by volume hydrochloric acid and heating at 140°C for 14 h; S2. washing the graphite sheet treated in step S1 and drying it at 120°C for 10 h; S3. adding the graphite sheet treated in step S3 to 200 mL of 4.5 mol / L HNO 3 The solution is heated at 140°C for 14 h; S4. The graphite sheet treated in step S3 is washed to neutrality and dried at 120°C for 10 h to obtain an oxidized graphite sheet.

[0080] (2) Use oxidized graphite sheets (0.3 cm*2*2 cm 2 ) is the anode, nickel mesh (2*2cm 2 ) was used as cathode, the working current density was set to 1.2 V, and electrolysis was performed for 16 h.

[0081] After treatment, the manganese ion content in the electrolytic manganese ore wastewater in the anode chamber was 1899 mg / L, the degradation rate was 73.8%, the ammonia nitrogen content was 2189 mg / L, and the removal rate was 40.8%; the manganese ion content in the electrolytic manganese ore wastewater in the cathode chamber was 3260 mg / L, the degradation rate was 55.0%, the ammonia nitrogen content was 3620 mg / L, and the removal rate was 2.1%.

[0082] Electrode post-treatment steps Example 1. Example 7

[0083] The electrolytic manganese ore wastewater was selected to contain high concentrations of manganese ions and ammonia nitrogen. The manganese ion concentration of the wastewater was 7249 mg / L, the ammonia nitrogen concentration was 3697 mg / L, the pH value was 7, the plate spacing was 9 cm, and the volume of the double-chamber electrolytic cell was 80 mL.

[0084] The specific steps are: (1) Place graphite felt (2*2 cm 2 ) to obtain oxidized graphite felt, specifically comprising: S1. adding graphite felt to 200 mL of 6% by volume hydrochloric acid and heating at 140°C for 14 h; S2. washing the graphite felt treated in step S1 and drying it at 120°C for 10 h; S3. adding the graphite felt treated in step S3 to 200 mL of 4.5 mol / L HNO 3 The solution is heated at 140°C for 14 h; S4. The graphite felt treated in step S3 is washed to neutrality and dried at 120°C for 10 h to obtain oxidized graphite felt.

[0085] (2) Use oxidized graphite felt (0.3 cm*2*2 cm 2) is the anode, nickel mesh (2*2cm 2 ) was used as cathode, the working voltage was set to 1.2 V, and electrolysis was performed for 16 h.

[0086] After treatment, the manganese ion content in the electrolytic manganese ore wastewater in the anode chamber was 1499 mg / L, the degradation rate was 79.3%, the ammonia nitrogen content was 1889 mg / L, and the removal rate was 48.9%; the manganese ion content in the electrolytic manganese ore wastewater in the cathode chamber was 2960 mg / L, the degradation rate was 59.2%, the ammonia nitrogen content was 3220 mg / L, and the removal rate was 12.9%.

[0087] Electrode post-treatment steps Example 1.

[0088] Those skilled in the art should note that the embodiments described in the present invention are merely exemplary, and various other substitutions, changes and improvements may be made within the scope of the present invention. Therefore, the present invention is not limited to the above embodiments, but only to the claims.

Claims

1. A method for treating electrolytic manganese wastewater using a carbon-based electrode, characterized in that The following steps are involved: (1) subjecting the carbon-based material to oxidation treatment to obtain an oxidized carbon-based material; (2) The oxidized carbon-based material is used as an anode and a cheap conductive material is used as a cathode, and electrolytic manganese wastewater is introduced into a double-chamber electrolytic cell for electrolytic treatment.

2. The method for treating electrolytic manganese wastewater using a carbon-based electrode according to claim 1, characterized in that: In step (1), the carbon-based material is one of graphite sheet, graphite felt and carbon cloth; In step (2), the cathode is a graphite sheet or a metal mesh.

3. The method for treating electrolytic manganese wastewater using a carbon-based electrode according to claim 2, characterized in that: The metal mesh is one of a nickel mesh, a copper mesh and an iron mesh.

4. The method for treating electrolytic manganese wastewater using a carbon-based electrode according to claim 1, characterized in that: In step (1), the oxidation treatment of the carbon-based material specifically includes: S1. Add carbon-based materials to 6-9% hydrochloric acid by volume, 120-140 o C heating for 8~14 h; S2. Cleaning the carbon-based material after treatment in step S1 and drying; S3. Add the carbon-based material treated in step S3 to a 4.5-5.5 mol / L HNO3 solution at 120-140 o C heating for 8~14 h; S4. The carbon-based material treated in step S3 is washed to neutrality and dried to obtain an oxidized carbon-based material.

5. The method for treating electrolytic manganese wastewater using a carbon-based electrode according to claim 1, characterized in that: The anode and the cathode have the same area, the distance between the anode and the cathode is 5 to 15 cm, and the anode and the cathode are separated by an ion exchange membrane.

6. The method for treating electrolytic manganese wastewater using a carbon-based electrode according to claim 1, characterized in that: In step (2), the working voltage in the double-chamber electrolyzer is 1.0-2.6 V, the electrolysis time is 8-40 h, or the current density is 5-30 mA / cm 2 , the electrolysis time is 8~40 h.

7. The method for treating electrolytic manganese wastewater using a carbon-based electrode according to claim 1, characterized in that: The electrolysis method is constant voltage electrolysis, constant current electrolysis, step-by-step multi-voltage electrolysis or step-by-step multi-current electrolysis, and the time for replacing the anode during the electrolysis process does not exceed 10 hours.

8. The method for treating electrolytic manganese wastewater using a carbon-based electrode according to claim 7, characterized in that: The electrolysis method is constant voltage electrolysis, and the working voltage in the double-chamber electrolytic cell is 1.2 V; Or the electrolysis method is step-by-step multi-voltage electrolysis, and the steps of step-by-step multi-voltage electrolysis are: working voltage is 1.0 V, electrolysis time is 2 to 4 h, working voltage is 1.1 V, electrolysis time is 2 to 4 h, working voltage is 1.2 V, and electrolysis is performed until the electrolytic manganese wastewater treatment is completed.

9. The method for treating electrolytic manganese wastewater using a carbon-based electrode according to claim 1, characterized in that: In step (2), the pH value of the electrolytic manganese wastewater is 6-9, or is pretreated to a pH value of 6-9.

10. Use of the method according to claims 1 to 9 in reducing the concentrations of manganese ions and ammonia nitrogen in electrolytic manganese wastewater.

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