Wastewater adsorbent, and preparation method therefor and use thereof

Abstract

Disclosed in the present invention are a wastewater adsorbent, and a preparation method therefor and the use thereof. The method comprises: mixing a carbon black powder and an ammonium salt solution, heating same for a hydrothermal reaction, followed by filtering, and washing the obtained filter residues with acid to obtain an ammonium-salt-modified carbon black; mixing and grinding a nickel-cobalt-manganese mixed salt and a sodium salt to obtain a mixture, mixing the mixture with an organic acid solution, evaporating same to remove water, subjecting same to a heating reaction in an inert atmosphere, and subjecting the reacted material to acid pickling to obtain a nickel-cobalt-manganese-sodium mixed salt; and mixing the nickel-cobalt-manganese-sodium mixed salt, the ammonium-salt-modified carbon black and a binding agent, and compacting, drying and heating same to obtain a multimetal-carbon-based adsorbent. The prepared multimetal-carbon-based adsorbent in the present invention has specific adsorption capacities for sodium, ammonium radicals and sulfate radicals; the carbon black powder serving as a substrate carbon material can adsorb multiple ions such as calcium, iron, manganese and cobalt all at the same time, such that diversified adsorption is achieved; in addition, the adsorbent can be reused after a desorption treatment and has a repeat adsorption capacity.

Description

A wastewater adsorbent and its preparation method and application Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and in particular relates to a wastewater adsorbent and a preparation method and application thereof. Background Art

[0002] At present, the synthesis method of ternary positive electrode materials is obtained by sintering lithium salts with ternary precursors. The ternary precursor synthesis process includes the following two types: 1. Dismantling and recycling of waste lithium ions / electrodes to obtain battery powder, roasting the battery powder, leaching with acid and oxygen, and extracting and purifying it to obtain a nickel-cobalt-manganese mixed salt, which is then synthesized with alkali and ammonia to obtain a ternary precursor product; 2. Acid leaching, precipitation and impurity removal of various minerals, and extraction and purification to obtain nickel salts, cobalt salts, and manganese salts respectively, which are then synthesized with nickel salts, cobalt salts, manganese salts, alkali and ammonia to obtain a ternary precursor product. In both synthesis processes of the above-mentioned ternary precursors, it is inevitable to use acid, especially sulfuric acid as a leaching agent, alkali as a precipitant and regulator, ammonia as a complexing agent, and organic extractants to extract nickel, cobalt and manganese metal ions. In order to prevent ammonium salts, sulfates and organic extractants from remaining in the nickel, cobalt and manganese salt solution, resulting in high levels of ammonium salts, sulfates and organic extractants in the ternary precursor, which causes the product to exceed the standard, multiple filter presses and washings are often used to remove sodium ions. Therefore, on the one hand, more pure water is needed to repeatedly rinse away ammonium salts, sulfates, organic extractants and other soluble impurities, increasing water consumption, generating more wastewater, and increasing wastewater treatment costs. On the other hand, as the number of washings increases, the concentrations of ammonium salts, sulfates and organic extractants in the generated wastewater become lower and lower, making treatment difficult and making it impossible to deeply remove ammonium salts, sulfates and organic extractants.

[0003] Summary of the Invention

[0004] The present invention aims to address at least one of the technical problems existing in the aforementioned prior art. To this end, the present invention provides a wastewater adsorbent, its preparation method, and its application. The first objective is to prepare the wastewater adsorbent, and the second objective is to provide a wastewater treatment method utilizing the wastewater treatment agent to deeply remove ammonium salts, sulfates, and organic extractants.

[0005] According to one aspect of the present invention, a method for preparing a wastewater adsorbent is provided, comprising the following steps:

[0006] S1: mixing carbon black powder with an ammonium salt solution, heating for hydrothermal reaction, and then filtering, and washing the resulting filter residue with acid to obtain ammonium salt-modified carbon black; mixing and grinding a nickel-cobalt-manganese mixed salt with a sodium salt to obtain a mixture, mixing the mixture with an organic acid solution, evaporating to remove water, and heating to react under an inert atmosphere. After the reaction, the material is acid-washed to obtain a nickel-cobalt-manganese sodium mixed salt;

[0007] S2: The nickel-cobalt-manganese sodium mixed salt, ammonium salt-modified carbon black, and a binder are mixed, compacted, dried, and heated to obtain a multi-metal-carbon-based adsorbent. The heating in step S2 is performed under a nitrogen atmosphere.

[0008] Wherein, after compaction, a certain shape such as flake, block, long rod, sphere, or irregular polygon is obtained.

[0009] In some embodiments of the present invention, in step S1, the carbon black powder is obtained by acid-oxygen leaching of battery powder recovered from lithium batteries. Furthermore, the average particle size of the carbon black powder is less than 0.1 mm.

[0010] In some embodiments of the present invention, in step S1, the ammonium salt solution is one or more of a solution of ammonium sulfate, ammonium bisulfate, ammonium carbonate, ammonium bicarbonate, ammonium chloride, ammonium phosphate or ammonium dihydrogen phosphate; preferably, the ammonium salt solution is one or both of a solution of ammonium sulfate or ammonium bisulfate.

[0011] In some embodiments of the present invention, the solid-liquid ratio of the carbon black powder to the ammonium salt solution is 10-500 g / L, and further, the solid-liquid ratio of the carbon black powder to the ammonium salt solution is 50-200 g / L.

[0012] In some embodiments of the present invention, the mass concentration of the ammonium salt solution is 0.1-30%, and further, the mass concentration of the ammonium salt solution is 1-10%.

[0013] In some embodiments of the present invention, in step S1, the temperature of the hydrothermal reaction is 100-400° C.; preferably, the time of the hydrothermal reaction is 1-10 h.

[0014] In some embodiments of the present invention, in step S1, the sodium salt is one or more of sodium acetate, sodium hydroxide, sodium sulfate, sodium phosphate, sodium chloride, sodium nitrate, sodium oxalate, sodium citrate, sodium manganate or sodium carbonate.

[0015] In some embodiments of the present invention, in step S1, the average particle size of the mixture is less than 100 μm.

[0016] In some embodiments of the present invention, in step S1, the acid is one or more of sulfuric acid, nitric acid, phosphoric acid or hydrochloric acid; further, the concentration of the acid is 0.1-5 mol / L.

[0017] In some embodiments of the present invention, in step S1, the nickel-cobalt-manganese mixed salt is prepared by recycling batteries; preferably, the mass ratio of the sodium salt to the nickel-cobalt-manganese mixed salt is (1-10): (0.1-30).

[0018] In some embodiments of the present invention, in step S1, the organic acid solution is one or more of oxalic acid, citric acid, acetic acid, formic acid or acetic acid solutions; the solid-liquid ratio of the mixture to the organic acid solution is 10: (50-200) g / mL, and further, the mass concentration of the organic acid solution is 1-40%.

[0019] In some embodiments of the present invention, in step S1, the temperature of the heating reaction is 300-1100° C.; preferably, the time of the heating reaction is 2-24 hours.

[0020] In some embodiments of the present invention, in step S2, the binder is one or more of calcium silicate, calcium alginate, silicate clay or sodium aluminosilicate; preferably, the mass ratio of the nickel cobalt manganese sodium mixed salt, ammonium salt modified carbon black and binder is (10-50): (30-70): (0.1-8).

[0021] In some embodiments of the present invention, in step S2, the heating temperature is 300-800° C., and further, the heating time is 2-24 hours.

[0022] In some embodiments of the present invention, in step S2, the density after compaction is greater than 1.8 g / cm 3 .

[0023] The present invention also provides a wastewater adsorbent prepared by the preparation method.

[0024] The present invention also provides application of the wastewater adsorbent in the treatment of ternary precursor wastewater.

[0025] In some embodiments of the present invention, the method for treating the ternary precursor wastewater includes: the ternary precursor wastewater is subjected to sedimentation, filtration, and strong oxidation to obtain primary treated wastewater, the wastewater adsorbent is added to the primary treated wastewater for adsorption treatment, the treated wastewater adsorbent is immersed in acid for desorption, and after 2-6 adsorption-desorption treatments, the treated wastewater is sent to secondary treatment, and the wastewater adsorbent is reused for adsorption treatment again. It should be noted that the ternary precursor wastewater is the wastewater generated by acid leaching, precipitation and impurity removal, extraction and separation, alkali addition, ammonia addition, and aging in the ternary precursor production process.

[0026] In some embodiments of the present invention, the solid-liquid ratio of the wastewater adsorbent to the primary treated wastewater is (0.5-20): (30-200) kg / L.

[0027] In some embodiments of the present invention, the acid used for the soaking desorption is one or more of sulfuric acid, nitric acid, phosphoric acid or hydrochloric acid, and the concentration thereof is further 0.01-3 mol / L.

[0028] According to a preferred embodiment of the present invention, there are at least the following beneficial effects:

[0029] 1. The wastewater adsorbent of the present invention has high stability and diverse adsorption options. After the carbon black powder in the wastewater adsorbent is modified with ammonium salt by hydrothermal method, the polarity and acid-base properties of the carbon black powder are greatly changed, and the adsorption performance for ammonium radicals is enhanced. In the nickel-cobalt-manganese mixed salt, manganese salt is the main material of the adsorbent polymetallic salt. The stability of the adsorbent is enhanced by adding cobalt salt / nickel salt. The carbon black powder is used as the base material of the adsorbent and heated to synthesize the polymetallic-carbon-based adsorbent. This can further enhance the inherent excellent performance of the porous carbon in the carbon black powder, improve its surface properties, help enhance the interaction between the adsorbent and the ions, and improve the adsorption performance. The polymetallic-carbon-based adsorbent prepared in the present invention has specific adsorption capacity for sodium, ammonium radicals, and sulfate radicals. The carbon black powder as the base carbon material can adsorb many ions such as calcium, iron, manganese, and cobalt at the same time, and has diverse adsorption. Furthermore, the adsorbent can be reused after desorption treatment, and has the ability of repeated adsorption.

[0030] 2. The method of the present invention significantly reduces production costs. The raw materials for the multi-metal-carbon-based adsorbent synthesized in the present invention can be recycled from waste batteries. Carbon black powder can be derived from the negative electrode material of waste batteries, and the nickel-cobalt-manganese-sodium mixed salt can be derived from the positive electrode material of waste batteries. Therefore, the main materials of the adsorbent are all recycled waste materials. Furthermore, the adsorbent synthesized in the present invention is reusable. After adsorption treatment of the primary treated wastewater, the adsorbent can be placed in acid for desorption treatment and reused. Therefore, the materials of the present invention are highly recyclable. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0032] FIG1 is a process flow chart of Example 1 of the present invention;

[0033] FIG2 is a SEM image of the wastewater adsorbent prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0035] Example 1

[0036] A preparation method of a wastewater adsorbent and a wastewater treatment method, referring to FIG1 , the specific process is as follows:

[0037] (1) Carbon black residue modification: Battery powder recovered from lithium batteries is subjected to acid-oxygen leaching to obtain carbon black residue. The carbon black residue is washed, dried, and ground to an average particle size of <0.1 mm to obtain carbon black residue powder. 34 g of carbon black residue powder is mixed with 200 mL of 3.3% ammonium sulfate solution and stirred to obtain carbon black residue slurry. The carbon black residue slurry is sent to a closed container and heated, and hydrothermally reacted at 160°C for 3 h 3 min. After cooling, it is filtered, and the filter residue is washed with dilute acid and dried to obtain ammonium sulfate-modified carbon black residue.

[0038] (2) Preparation of a sodium nickel-cobalt-manganese mixed salt: The nickel-cobalt-manganese mixed salt obtained by recycling a battery was mixed with sodium sulfate and ground to an average particle size of <100 μm to obtain a mixture, the mixture was uniformly mixed with a 6.12 wt % oxalic acid solution, solid-liquid separation was performed, water was evaporated, heated at 430° C. under an inert atmosphere, kept at a constant temperature for 3 h 44 min, cooled, pickled with 0.34 mol / L hydrochloric acid, washed, and dried to obtain a sodium nickel-cobalt-manganese mixed salt.

[0039] The mass ratio of sodium sulfate to nickel-cobalt-manganese mixed salt is 3:12, and the solid-liquid ratio of the mixture to the oxalic acid solution is 10:50 g / mL.

[0040] (3) Synthesis of multi-metal-carbon-based adsorbent: 15.8 g of nickel-cobalt-manganese sodium mixed salt, 34 g of ammonium sulfate-modified carbon black residue, and 5 g of silicate clay were mixed and compacted to obtain a certain thin flake shape with a compaction density of 2.53 g / cm 3 , dried, heated at 485°C under a nitrogen atmosphere, kept constant for 2h12min, and cooled to obtain a multi-metal-carbon based adsorbent.

[0041] (4) Treatment of wastewater by adsorption by adsorbent: The wastewater generated by the preparation of the ternary precursor is subjected to sedimentation, filtration, and strong oxidation to obtain primary treated wastewater, which is then treated with a multi-metal-carbon based adsorbent for adsorption treatment. The treated adsorbent is then immersed in 0.34 mol / L hydrochloric acid for desorption. After 5 adsorption-desorption treatments, the treated wastewater is sent to secondary treatment, and the adsorbent is reused for adsorption treatment again.

[0042] Among them, the solid-liquid ratio of adsorbent to wastewater is 1:13 g / mL.

[0043] Example 2

[0044] A method for preparing a wastewater adsorbent and a method for treating wastewater, the specific process is as follows:

[0045] (1) Carbon black residue modification: Battery powder recovered from lithium batteries is subjected to acid-oxygen leaching to obtain carbon black residue. The carbon black residue is washed, dried, and ground to an average particle size of <0.1 mm to obtain carbon black residue powder. 45 g of carbon black residue powder is mixed with 280 mL of 3.7% ammonium sulfate solution to obtain carbon black residue slurry. The carbon black residue slurry is sent to a closed container and heated, and hydrothermally reacted at 185°C for 2 h 13 min. After cooling, it is filtered, and the filter residue is washed with dilute acid and dried to obtain ammonium sulfate-modified carbon black residue.

[0046] (2) Preparation of a sodium nickel-cobalt-manganese mixed salt: The sodium nickel-cobalt-manganese mixed salt obtained by recycling a battery was mixed with sodium sulfate and ground to an average particle size of <100 μm to obtain a mixture, the mixture was uniformly mixed with a 3.41 wt % oxalic acid solution, solid-liquid separation was performed, water was evaporated, heated at 425° C. under an inert atmosphere, kept at a constant temperature for 3 h 54 min, cooled, pickled with 0.34 mol / L hydrochloric acid, washed, and dried to obtain a sodium nickel-cobalt-manganese mixed salt.

[0047] The mass ratio of sodium sulfate to nickel-cobalt-manganese mixed salt is 5:17, and the solid-liquid ratio of the mixture to the oxalic acid solution is 10:65 g / mL.

[0048] (3) Synthesis of multi-metal-carbon based adsorbent: 22 g of nickel-cobalt-manganese sodium mixed salt, 45 g of ammonium sulfate modified carbon black residue, and 7-silicic acid clay were mixed and compacted to obtain a certain thin flake with a compaction density of 2.23 g / cm 3 , dried, heated at 485°C under a nitrogen atmosphere, kept constant for 2h12min, and cooled to obtain a multi-metal-carbon based adsorbent.

[0049] The mass ratio of nickel-cobalt-manganese sodium mixed salt, ammonium sulfate-modified carbon black slag, and silicate clay is 35:70:2.3.

[0050] (4) Treatment of wastewater by adsorption by adsorbent: The wastewater generated by the preparation of the ternary precursor is subjected to sedimentation, filtration, and strong oxidation to obtain primary treated wastewater, which is then treated with a multi-metal-carbon based adsorbent for adsorption treatment. The treated adsorbent is then immersed in 0.34 mol / L hydrochloric acid for desorption. After 5 adsorption-desorption treatments, the treated wastewater is sent to secondary treatment, and the adsorbent is reused for adsorption treatment again.

[0051] Among them, the solid-liquid ratio of adsorbent to wastewater is 1:9 kg / L.

[0052] FIG2 is a SEM image of the wastewater adsorbent prepared in this embodiment. As can be seen from the image, the adsorbent has a rough surface and a porous structure.

[0053] Example 3

[0054] A method for preparing a wastewater adsorbent and a method for treating wastewater, the specific process is as follows:

[0055] (1) Carbon black residue modification: Battery powder recovered from lithium batteries is subjected to acid-oxygen leaching to obtain carbon black residue. The carbon black residue is washed, dried, and ground to an average particle size of <0.1 mm to obtain carbon black residue powder. 36 g of carbon black residue powder is mixed with 240 mL of 4.4% ammonium chloride solution to obtain carbon black residue slurry. The carbon black residue slurry is sent to a closed container for heating and hydrothermal reaction at 160°C for 2 h 33 min. After cooling, it is filtered, and the filter residue is washed with dilute acid and dried to obtain ammonium chloride-modified carbon black residue.

[0056] (2) Preparation of a sodium nickel-cobalt-manganese mixed salt: The nickel-cobalt-manganese mixed salt obtained by recycling batteries was mixed with sodium sulfate and ground to an average particle size of <100 μm to obtain a mixture, the mixture was uniformly mixed with a 6.33 wt % oxalic acid solution, solid-liquid separation was performed, water was evaporated, heated at 430° C. under an inert atmosphere, kept at a constant temperature for 3 h 34 min, cooled, pickled with 0.34 mol / L hydrochloric acid, washed, and dried to obtain a sodium nickel-cobalt-manganese mixed salt.

[0057] The mass ratio of sodium sulfate to nickel-cobalt-manganese mixed salt is 4:13, and the solid-liquid ratio of the mixture to the oxalic acid solution is 10:50 g / mL.

[0058] (3) Synthesis of multi-metal-carbon based adsorbent: 17 g of nickel-cobalt-manganese sodium mixed salt, 36 g of ammonium chloride modified carbon black slag, and 5 g of silicate clay were mixed and compacted to obtain a certain block with a compaction density of 2.07 g / cm 3 , dried, heated at 485°C under a nitrogen atmosphere, kept constant for 2h12min, and cooled to obtain a multi-metal-carbon based adsorbent.

[0059] (4) Treatment of wastewater by adsorption by adsorbent: The wastewater generated by the preparation of the ternary precursor is subjected to sedimentation, filtration, and strong oxidation to obtain primary treated wastewater, which is then treated with a multi-metal-carbon based adsorbent for adsorption treatment. The treated adsorbent is then immersed in 0.34 mol / L hydrochloric acid for desorption. After 5 adsorption-desorption treatments, the treated wastewater is sent to secondary treatment, and the adsorbent is reused for adsorption treatment again.

[0060] Among them, the solid-liquid ratio of adsorbent to wastewater is 1:7 kg / L.

[0061] Example 4

[0062] A method for preparing a wastewater adsorbent and a method for treating wastewater, the specific process is as follows:

[0063] (1) Carbon black residue modification: Battery powder recovered from lithium batteries is subjected to acid-oxygen leaching to obtain carbon black residue. The carbon black residue is washed, dried, and ground to an average particle size of <0.1 mm to obtain carbon black residue powder. 25 g of carbon black residue powder is mixed with 200 mL of 5.3% ammonium chloride solution and stirred to obtain carbon black residue slurry. The carbon black residue slurry is sent to a closed container and heated, and hydrothermally reacted at 160°C for 3 hours and 8 minutes. After cooling, it is filtered, and the filter residue is washed with dilute acid and dried to obtain ammonium chloride-modified carbon black residue.

[0064] (2) Preparation of a sodium nickel-cobalt-manganese mixed salt: The nickel-cobalt-manganese mixed salt obtained by recycling batteries was mixed with sodium sulfate and ground to an average particle size of <100 μm to obtain a mixture, the mixture was uniformly mixed with a 6.12 wt % oxalic acid solution, solid-liquid separation was performed, water was evaporated, heated at 430° C. under an inert atmosphere, kept at a constant temperature for 3 h 17 min, cooled, pickled with 0.34 mol / L hydrochloric acid, washed, and dried to obtain a sodium nickel-cobalt-manganese mixed salt.

[0065] The mass ratio of sodium sulfate to nickel-cobalt-manganese mixed salt is 5:15, and the solid-liquid ratio of the mixture to the oxalic acid solution is 10:50 g / mL.

[0066] (3) Synthesis of multi-metal-carbon-based adsorbent: 8 g of nickel-cobalt-manganese sodium mixed salt, 25 g of ammonium chloride-modified carbon black slag, and 3 g of silicate clay were mixed and compacted to obtain a certain block with a compaction density of 2.47 g / cm 3 , dried, heated at 485°C under a nitrogen atmosphere, kept constant for 2h12min, and cooled to obtain a multi-metal-carbon based adsorbent.

[0067] (4) Treatment of wastewater by adsorption by adsorbent: The wastewater generated by the preparation of the ternary precursor is subjected to sedimentation, filtration, and strong oxidation to obtain primary treated wastewater, which is then treated with a multi-metal-carbon based adsorbent for adsorption treatment. The treated adsorbent is then immersed in 0.34 mol / L hydrochloric acid for desorption. After 5 adsorption-desorption treatments, the treated wastewater is sent to secondary treatment, and the adsorbent is reused for adsorption treatment again.

[0068] Among them, the solid-liquid ratio of adsorbent to wastewater is 1:10g / L.

[0069] Comparative Example 1

[0070] The difference between this comparative example and Example 1 is that the carbon black slag in step (1) is not subjected to modification treatment.

[0071] Comparative Example 2

[0072] The difference between this comparative example and Example 1 is that no nickel-cobalt-manganese-sodium mixed salt is added in step (3).

[0073] Comparative Example 3

[0074] The difference between this comparative example and Example 3 is that no nickel-cobalt-manganese-sodium mixed salt is added in step (3).

[0075] Table 1 Impurity content of wastewater in Examples 1-4 and Comparative Examples 1-3 before and after adsorption treatment

[0076]

[0077]

[0078] As can be seen from Table 1, compared with Comparative Example 1, the ammonia nitrogen removal amount in the wastewater of Examples 1-4 after modification with ammonium salts is significantly improved. On the other hand, compared with Comparative Example 2 and Comparative Example 3, the removal amount of nickel and sodium in the wastewater is significantly improved after the mixed salt of nickel, cobalt, manganese and sodium is added to Examples 1-4.

[0079] While the embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof may be combined with one another unless there is a conflict.

Claims

1. A method for preparing a wastewater adsorbent, It is characterized in that The following steps are involved: S1: mixing carbon black powder with an ammonium salt solution, heating for hydrothermal reaction, and then filtering, washing the obtained filter residue with acid to obtain ammonium salt modified carbon black; mixing and grinding a nickel-cobalt-manganese mixed salt with a sodium salt to obtain a mixture, mixing the mixture with an organic acid solution, evaporating to remove water, heating for reaction under an inert atmosphere, and acid-washing the reaction material to obtain a nickel-cobalt-manganese sodium mixed salt; S2: The nickel-cobalt-manganese sodium mixed salt, ammonium salt-modified carbon black and a binder are mixed, compacted, dried and heated to obtain a multi-metal-carbon-based adsorbent.

2. The preparation method according to claim 1, It is characterized in that In step S1, the carbon black powder is obtained by acid-oxygen leaching of battery powder recovered from lithium batteries.

3. The preparation method according to claim 1, It is characterized in that In step S1, the ammonium salt solution is one or more of ammonium sulfate, ammonium bisulfate, ammonium carbonate, ammonium bicarbonate, ammonium chloride, ammonium phosphate or diammonium phosphate; the solid-liquid ratio of the carbon black powder to the ammonium salt solution is 10-500 g / L, and the mass concentration of the ammonium salt solution is 0.1-30%.

4. The preparation method according to claim 1, It is characterized in that In step S1, the temperature of the hydrothermal reaction is 100-400° C.; preferably, the time of the hydrothermal reaction is 1-10 h.

5. The preparation method according to claim 1, It is characterized in that In step S1, the nickel-cobalt-manganese mixed salt is prepared by recycling batteries; preferably, the mass ratio of the sodium salt to the nickel-cobalt-manganese mixed salt is (1-10): (0.1-30).

6. The preparation method according to claim 1, It is characterized in that In step S1, the organic acid solution is one or more of oxalic acid, citric acid, acetic acid, formic acid or acetic acid solutions; the solid-liquid ratio of the mixture to the organic acid solution is 10: (50-200) g / mL, and the mass concentration of the organic acid solution is 1-40%.

7. The preparation method according to claim 1, It is characterized in that In step S1, the temperature of the heating reaction is 300-1100°C; preferably, the time of the heating reaction is 2-24h.

8. The preparation method according to claim 1, It is characterized in that In step S2, the binder is one or more of calcium silicate, calcium alginate, silicate clay or sodium aluminosilicate; preferably, the mass ratio of the nickel cobalt manganese sodium mixed salt, ammonium salt modified carbon black and the binder is (10-50): (30-70): (0.1-8).

9. A wastewater adsorbent, It is characterized in that Prepared by the preparation method described in any one of claims 1 to 8.

10. Use of the wastewater adsorbent as claimed in claim 9 in the treatment of ternary precursor wastewater.