A pretreatment method for lithium battery wastewater containing sodium sulfate

Abstract

The application discloses a pretreatment method of lithium battery wastewater containing sodium sulfate, wherein sodium sulfate is added into lithium battery wastewater, then sulfuric acid is added, and then sodium polyphosphate is added; the lithium battery wastewater is subjected to first electrocatalytic oxidation; then an ultraviolet lamp is turned on, and the lithium battery wastewater is subjected to second electrocatalytic oxidation and coupling ultraviolet activation to obtain pretreated wastewater. The method utilizes sodium sulfate in the wastewater to generate sodium persulfate, saves a large amount of cost, and simultaneously subjects organic matters in the wastewater to electrocatalytic oxidation coupling persulfate oxidation treatment, improves the yield and generation rate of ·OH, improves the degradation rate and degradation effect of the organic matters, and realizes efficient pretreatment of the lithium battery wastewater containing sodium sulfate.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sewage treatment, and particularly relates to a treatment method of lithium battery wastewater containing sodium sulfate. BACKGROUND

[0002] With the continuous expansion of the production of new energy vehicles, the lithium battery industry has developed rapidly, and the treatment of lithium battery wastewater has also attracted more and more attention. A large amount of raffinate wastewater, discharge wastewater, cleaning wastewater, and container spraying wastewater are generated in the production and recycling process of lithium batteries. These wastewaters contain a large amount of salt and organic matter, have very low biodegradability, and are not easy to biodegrade. Direct discharge not only seriously pollutes the environment, but also causes resource waste.

[0003] At present, lithium battery wastewater mainly recovers salt through MVR evaporation. If the organic matter concentration in the wastewater is too high, it will affect the purity of the salt and also cause the MVR system to be blocked, foamed, etc. Therefore, it is necessary to pretreat the organic matter in the wastewater before entering the MVR. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a pretreatment method of lithium battery wastewater containing sodium sulfate. The present application has good treatment effect, low cost, and can recycle the salt components in the wastewater to treat the organic matter in the lithium battery wastewater containing sodium sulfate.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0006] The present application is a pretreatment method of lithium battery wastewater containing sodium sulfate. Sulfuric acid is added to the lithium battery wastewater, and then sodium polyphosphate is added. The lithium battery wastewater is subjected to first electrocatalytic oxidation, and then the ultraviolet lamp is turned on to subject the lithium battery wastewater to second electrocatalytic oxidation and coupling ultraviolet activation to obtain pretreated wastewater.

[0007] The method of the present application first adds sulfuric acid to the lithium battery wastewater containing sodium sulfate to adjust the pH value of the lithium battery wastewater containing sodium sulfate, thereby providing an acidic condition for the subsequent reaction. Then, the anode additive, sodium polyphosphate, is added to the lithium battery wastewater to perform first electrocatalytic oxidation. The electrocatalytic oxidation produces sodium persulfate and degrades the organic pollutants in the wastewater at the same time. Subsequently, the ultraviolet lamp tube is placed in the wastewater, and the ultraviolet lamp is turned on to activate the sodium persulfate. The electrocatalytic oxidation is coupled with the persulfate oxidation to degrade the organic pollutants in the wastewater. Finally, the sodium persulfate is reduced to sodium sulfate. During this process, the organic matter is degraded, and the COD removal rate of the wastewater is as high as 92% or more.

[0008] Preferably, the mass ratio of the sulfuric acid to the sodium sulfate in the lithium battery wastewater is 0.5-2:1. The inventors have found that the purity of the generated sodium persulfate is higher under this preferred scheme.

[0009] Preferably, the sodium polyphosphate is added in an amount of 1-4 g / L. In the present application, 1-4 g / L means 1-4 g of sodium polyphosphate per liter of lithium battery wastewater.

[0010] Preferably, the temperature of the first electro-catalytic oxidation is 20-45°C, and the time is 1-6 h.

[0011] Preferably, the current density during the first electro-catalytic oxidation is 1-5 A / m 2 . The inventor found that using the current density in the range can avoid electrolysis of water, and can generate sodium persulfate with high purity. If the current is too high, water is easily electrolyzed, energy is wasted, and the purity of the generated sodium persulfate is not so high.

[0012] Preferably, the current density during the second electro-catalytic oxidation is 100-1000 A / m 2 . Using a high current density during the second electro-catalytic oxidation can effectively degrade organic pollutants in water.

[0013] Preferably, the irradiation intensity of the ultraviolet lamp is 100-300 W / m 2 . The inventor found that controlling the irradiation intensity of the ultraviolet lamp in the range can best activate the persulfate salt, promote the efficient degradation of organic pollutants in water by the persulfate salt, and too high or too low irradiation intensity will reduce the degradation effect, and too high irradiation intensity will waste energy

[0014] Preferably, the pretreated wastewater enters the MVR evaporation system.

[0015] Compared with the prior art, the present application has the following advantages:

[0016] 1. The sodium persulfate is generated by using sodium sulfate in wastewater, which realizes the recycling of resources and saves a lot of cost.

[0017] 2. The electro-catalytic oxidation coupled with persulfate oxidation treatment of organic matter in wastewater improves the yield and generation rate of ·OH, and improves the degradation rate and degradation effect of organic matter.

[0018] 3. The process is simple, easy to control, safe and reliable. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a lithium battery wastewater treatment process flowchart according to the present application.

[0020] Figure 2 is a schematic diagram of an electro-catalytic oxidation coupled with ultraviolet light activation reaction device according to the present application.

[0021] The following are the labels in the schematic diagram: 1-Cover plate; 2-UV lamp; 3-Circulating water inlet valve; 4-Condensate pipe; 5-Circulating pipe; 6-Electrocatalytic reaction equipment; 7-Reaction tank; 8-Circulating water outlet valve; 9-Water outlet valve; 10-Water outlet pipe; 11-Lamp support. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments, but the implementation of the present invention is not limited thereto.

[0023] like Figure 1 and Figure 2 As shown, the workflow of the present invention is as follows: Open the cover plate (1), add wastewater into the reaction tank (7), then add a certain amount of sulfuric acid, and then cover the cover plate (1). The cover plate (1) has an air outlet and a dosing hole; open the circulating water inlet valve (3) and the circulating water outlet valve (8), turn on the electrocatalytic reaction device (6), and add a certain amount of sodium polyphosphate at the same time. The electrocatalytic reaction device (6) has a built-in circulating pump and an electrode group. Set a certain current density and control the reaction temperature through the condensate pipe (4); after the reaction has been going on for a period of time, turn on the ultraviolet lamp (2). The ultraviolet lamp (2) is fixed by the lamp holder (11); adjust the current density. After the reaction is completed, open the outlet valve (9). The degraded wastewater is discharged from the outlet pipe (10) and enters the MVR evaporation system.

[0024] The effects of the present invention will be further explained below with reference to specific embodiments.

[0025] Example 1

[0026] Table 1 shows the water quality indicators of lithium battery extraction wastewater from a waste battery recycling company in Hunan.

[0027] Table 1. Water quality indicators of lithium battery leaching wastewater from a waste battery recycling company in Hunan Province.

[0028]

[0029] A method for treating lithium battery wastewater comprises the following steps:

[0030] 1L of lithium battery wastewater (as shown in Table 1) was added to the reaction vessel, followed by 9.2g of sulfuric acid. After mixing thoroughly, 1g of sodium polyphosphate was added and dissolved. The electrocatalytic oxidation equipment was then turned on, with a titanium electrode as the cathode and a boron-doped diamond electrode as the anode. The distance between the cathode and anode plates was 2mm, and the anode area was 420cm². 2 The current density is 5A / m 2 The temperature was controlled at 25℃ during the reaction. After 2 hours of reaction, the ultraviolet lamp was turned on, and the irradiance of the ultraviolet lamp was adjusted to 100W / m². 2 Adjust the current density to 500A / m 2The COD removal rate of the wastewater is 93.28% after 1h of reaction.

[0031] Comparative Example 1

[0032] 1L of lithium battery wastewater with the properties in Table 1 was added to a reaction container, followed by 9.2g of sulfuric acid. After mixing, 1g of sodium polyphosphate was added, and after dissolution, the electro-catalytic oxidation device was started, with a titanium electrode as the cathode and a boron-doped diamond electrode as the anode. The distance between the cathode and anode plates was 2mm, and the anode area was 420cm 2 . The current density was 0.5A / m 2 . During the reaction, the temperature was controlled at 25℃, and after 2h of reaction, the UV lamp was turned on, the UV lamp irradiation intensity was adjusted to 100W / m 2 , and the current density was adjusted to 500A / m 2 . After 1h of reaction, the COD removal rate of the wastewater was 72.36%.

[0033] Example 2

[0034] The water quality indicators of the lithium battery extraction concentrate liquid of a waste battery recycling enterprise in Hunan are shown in Table 2.

[0035] Table 2 Water quality indicators of the extraction concentrate liquid of a waste battery recycling enterprise in Hunan

[0036]

[0037]

[0038] A lithium battery wastewater treatment method was performed in the following order:

[0039] 1L of lithium battery wastewater with the properties in Table 2 was added to a reaction container, followed by 35.4g of sulfuric acid. After mixing, 3g of sodium polyphosphate was added, and after dissolution, the electro-catalytic oxidation device was started, with a titanium electrode as the cathode and a boron-doped diamond electrode as the anode. The distance between the cathode and anode plates was 2mm, and the anode area was 420cm 2 . The current density was 1A / m 2 . During the reaction, the temperature was controlled at 35℃, and after 6h of reaction, the UV lamp was turned on, the UV lamp irradiation intensity was adjusted to 300W / m 2 , and the current density was adjusted to 700A / m 2 . After 2h of reaction, the COD removal rate of the wastewater was 97.34%.

[0040] Comparative Example 2

[0041] A lithium battery wastewater of 1 L with the properties in Table 2 was added to a reaction vessel, followed by 35.4 g of sulfuric acid, 3 g of sodium polyphosphate was added after mixing, and the electro-catalytic oxidation device was started after dissolution, wherein the cathode was a titanium electrode, the anode was a boron-doped diamond electrode, the distance between the cathode and the anode was 2 mm, the anode area was 420 cm 2 , the current density was 1 A / m 2 , the temperature was controlled at 35 ℃ during the reaction, after 6 h of reaction, the ultraviolet lamp tube was started, the ultraviolet lamp irradiation intensity was adjusted to 300 W / m 2 , the current density was adjusted to 50 A / m 2 , and the wastewater COD removal rate was 55.27% after 2 h of reaction.

[0042] Example 3

[0043] The lithium battery wastewater of a lithium battery production enterprise in Zhejiang had the properties in Table 3.

[0044] Table 3 Properties of lithium battery wastewater of a lithium battery production enterprise in Zhejiang

[0045]

[0046] A lithium battery wastewater treatment method was performed in the following order:

[0047] A lithium battery wastewater of 1 L with the properties in Table 3 was added to a reaction vessel, followed by 13.2 g of sulfuric acid, 2 g of sodium polyphosphate was added after mixing, and the electro-catalytic oxidation device was started after dissolution, wherein the cathode was a titanium electrode, the anode was a boron-doped diamond electrode, the distance between the cathode and the anode was 2 mm, the anode area was 420 cm 2 , the current density was 3 A / m 2 , the temperature was controlled at 45 ℃ during the reaction, after 4 h of reaction, the ultraviolet lamp tube was started, the ultraviolet lamp irradiation intensity was adjusted to 200 W / m 2 , the current density was adjusted to 600 A / m 2 , and the wastewater COD removal rate was 95.76% after 1 h of reaction.

[0048] Comparative Example 3

[0049] A lithium battery wastewater of 1 L with the properties in Table 3 was added to a reaction vessel, followed by 13.2 g of sulfuric acid, 2 g of sodium polyphosphate was added after mixing, and the electro-catalytic oxidation device was started after dissolution, wherein the cathode was a titanium electrode, the anode was a boron-doped diamond electrode, the distance between the cathode and the anode was 2 mm, the anode area was 420 cm 2 , the current density was 3 A / m 2 , the temperature was controlled at 45 ℃ during the reaction, after 4 h of reaction, the ultraviolet lamp tube was started, the ultraviolet lamp irradiation intensity was adjusted to 50 W / m 2 , the current density was adjusted to 600 A / m2 The removal rate of COD of the wastewater is 77.53% after 1h of reaction.

[0050] The degradation effects of the examples and comparative examples 1-3 show that the sodium persulfate prepared by electro-catalytic oxidation is coupled with electro-catalysis and ultraviolet light to activate the persulfate salt oxidation to degrade various lithium battery wastewater, and good effects are achieved, which shows that the process method has good effects on the degradation of organic matters in lithium battery wastewater.

[0051] The above examples are preferred embodiments of the present application, but the embodiments of the present application are not limited to the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A method for the pretreatment of lithium battery wastewater containing sodium sulfate, characterized by: Sulfuric acid is added into lithium battery wastewater, then sodium polyphosphate is added, to prepare sodium persulfate by first electrocatalytic oxidation of lithium battery wastewater, then a UV lamp is turned on, to oxidize and degrade organic pollutants in wastewater by second electrocatalytic oxidation coupled with UV-activated sodium persulfate, to obtain pretreated wastewater; The pretreated wastewater enters an MVR evaporation system; The mass ratio of sulfuric acid to sodium sulfate in lithium battery wastewater is 0.5-2:

1. The density of the electric current in the first electro-catalytic oxidation process is 1-5 A / m 2 ; The density of the electric current in the second electro-catalytic oxidation process is 100-1000 A / m 2 .

2. The method for pretreatment of lithium battery wastewater containing sodium sulfate according to claim 1, characterized in that: The addition amount of sodium polyphosphate is 1-4 g / L.

3. The method for pretreatment of lithium battery wastewater containing sodium sulfate according to claim 1, characterized in that: The temperature of the first electrocatalytic oxidation is 20-45℃, and the time is 1-6 h.

4. The method for pretreatment of lithium battery wastewater containing sodium sulfate according to claim 1, characterized in that: The irradiation intensity of the ultraviolet lamp is 100-300 W / m 2 .

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