Tunnel-type manganese dioxide, method for preparing the same, and use thereof

Abstract

The application provides a tunnel type manganese dioxide and a preparation method and application thereof. The preparation method comprises the following steps: mixing a manganese precursor and an oxidizing agent in a solvent to obtain a mixed solution; the manganese precursor comprises manganese sulfate, and the oxidizing agent comprises ammonium persulfate and / or potassium permanganate; the manganese precursor: the oxidizing agent: the solvent is 10-30 mmol: 10-60 mmol: 50-70 ml; the pH value of the mixed solution is adjusted to be acidic, and the tunnel type manganese dioxide is obtained through a hydrothermal reaction; the tunnel type manganese dioxide comprises beta-MnO2, gamma-MnO2 or alpha-MnO2. The application can control the reaction environment and then provide an excellent nucleation growth environment for oxidized manganese, and the effect is remarkable.

Description

Technical Field

[0001] This invention belongs to the field of manganese oxide preparation technology, specifically relating to a tunnel-type manganese dioxide, its preparation method, and its application. Background Technology

[0002] Ternary lithium batteries possess advantages such as high energy density, long lifespan, and low self-discharge, making them a primary material for power transmission and electrochemical energy storage. Over the past three decades, the demand for ternary lithium batteries has increased significantly due to the rapid growth of electric vehicles. Typically, the primary cathode material in ternary lithium batteries is LiCo. x Mn y Ni z O2, in which manganese is the main structural metal, and the doping of cobalt and nickel is usually 10%-33%. Under certain special circumstances, such as extreme conditions or battery failure, Co and Ni in the material structural units will gradually dissolve into the electrolyte, affecting the battery's performance and lifespan.

[0003] Given the widespread use of Co and Ni in industries such as semiconductors, battery manufacturing, and electroplating, any leaks like the one described above would threaten the environment and the effectiveness of batteries. To address this issue, researchers are dedicated to developing high-performance Co and Ni adsorbents. Among these, inorganic ionic materials are considered the most stable type of adsorbent. However, most inorganic ionic materials are limited by their relatively conventional binding mechanisms, such as ion adsorption and lattice substitution, making it difficult to achieve breakthrough optimization in their binding effects with cobalt and nickel, such as the stability of the adsorbed complex. Summary of the Invention

[0004] To address the technical problem that existing cobalt-nickel (Co) and Ni adsorbents are limited by conventional single ion adsorption methods, making it difficult to achieve breakthrough optimization in their binding effect with cobalt and nickel, this invention provides a method for preparing tunnel-type manganese dioxide, comprising the following steps:

[0005] A manganese precursor and an oxidant are mixed in a solvent to obtain a mixed solution; the manganese precursor includes manganese sulfate, and the oxidant includes ammonium persulfate and / or potassium permanganate; the ratio of manganese precursor: oxidant: solvent is 10-30 mmol: 10-60 mmol: 50-70 ml.

[0006] The pH of the mixed solution was adjusted to acidic, and a hydrothermal reaction was carried out to obtain tunnel-type manganese dioxide; the tunnel-type manganese dioxide includes β-MnO2, γ-MnO2 or α-MnO2.

[0007] Furthermore, the β-MnO2 is in the form of nanorods with a size structure of [1x1]; the γ-MnO2 is in the form of microspheres with a size structure of [1x2]; and the α-MnO2 is in the form of nanoneedles with a size structure of [2x2].

[0008] Furthermore, the step of adjusting the pH of the mixed solution to acidic includes: adding an acid solution to the mixed solution to adjust the pH value of the mixed solution to 2-5; wherein the concentration of the acid solution is 0.1-1 mol / L, and the acid solution includes nitric acid.

[0009] Furthermore, the preparation of β-MnO2 includes: the manganese precursor: the oxidant: the solvent is 10-30 mmol: 10-40 mmol: 50-70 ml; the manganese precursor is manganese sulfate, the oxidant is ammonium persulfate, and the acid solution adjusts the pH of the mixed solution to 2-4.

[0010] The preparation of γ-MnO2 includes: manganese precursor: oxidant: solvent = 10-30 mmol: 10-40 mmol: 50-70 ml; the manganese precursor is manganese sulfate, and the oxidant is ammonium persulfate; the acid solution is used to adjust the pH of the mixed solution to 2-4.

[0011] The preparation of α-MnO2 includes: manganese precursor: oxidant: solvent = 10-30 mmol: 20-60 mmol: 50-70 ml; the manganese precursor is manganese sulfate, and the oxidant is potassium permanganate; the acid solution is used to adjust the pH of the mixed solution to 3-5.

[0012] Furthermore, in the step of adjusting the pH of the mixed solution to acidic and obtaining tunnel-type manganese dioxide through a hydrothermal reaction, the reaction temperature of the hydrothermal reaction is 70-160°C, the heating time of the hydrothermal reaction is 10-40 min, the holding time of the hydrothermal reaction is 8-32 h, and the pressure of the hydrothermal reaction is 0.1-0.15 MPa.

[0013] Furthermore, the pH of the mixed solution is adjusted to acidic, and a hydrothermal reaction is carried out to obtain tunnel-type manganese dioxide. The preparation of β-MnO2 includes: the reaction temperature of the hydrothermal reaction is 120-160℃, the heating time of the hydrothermal reaction is 20-40 min, and the reaction time of the hydrothermal reaction is 8-16 h.

[0014] Furthermore, the pH of the mixed solution is adjusted to acidic, and a hydrothermal reaction is carried out to obtain tunnel-type manganese dioxide. The preparation of γ-MnO2 includes: the reaction temperature of the hydrothermal reaction is 70-110℃, the heating time of the hydrothermal reaction is 10-30 min, and the reaction time is 16-32 h.

[0015] Furthermore, the pH of the mixed solution is adjusted to acidic, and a hydrothermal reaction is carried out to obtain tunnel-type manganese dioxide. The preparation of α-MnO2 includes the following steps: the reaction temperature of the hydrothermal reaction is 80-120℃, the heating time of the hydrothermal reaction is 20-30 min, and the holding time of the hydrothermal reaction is 16-32 h.

[0016] This invention provides a tunnel-type manganese dioxide, which is prepared by any of the preparation methods described above, wherein the tunnel-type manganese dioxide includes β-MnO2, γ-MnO2 and α-MnO2;

[0017] The β-MnO2 is in the form of nanorods with a size structure of [1x1]; the γ-MnO2 is in the form of microspheres with a size structure of [1x2]; and the α-MnO2 is in the form of nanoneedles with a size structure of [2x2].

[0018] This invention provides an application of tunnel-type manganese dioxide prepared by any of the above methods, or tunnel-type manganese dioxide as described above, in the treatment of cobalt and nickel wastewater. The cobalt and nickel wastewater treatment is carried out in an acidic environment, and the cobalt concentration in the cobalt and nickel wastewater is 10-30 mg / L, and the cobalt and nickel concentrations in the cobalt and nickel wastewater are 10-30 mg / L. The dosage concentration of the tunnel-type manganese dioxide is ≤0.5 g / L.

[0019] Compared with the prior art, the present invention has at least the following advantages:

[0020] This invention provides a method for preparing tunnel-type manganese dioxide. An acidic solution combined with high-pressure solvothermal treatment creates an excellent nucleation and growth environment, allowing the manganese precursor and oxidant to rapidly oxidize and reduce, forming manganese oxide crystals of a specific size. The main reactions are as follows:

[0021] 2MnSO4+(NH4)2S2O8→2β-MnO2+(NH4)2SO4+H2SO4(120~160℃, 8~16h)

[0022] 2MnSO4+(NH4)2S2O8→2γ-MnO2+(NH4)2SO4+H2SO4(70~110℃, 16~32h)

[0023] 3MnSO4+2KMnO4→5α-MnO2+K2SO4 (80~120℃, 16~24h) Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the process and mechanism for recovering cobalt and nickel ions from different tunnel-type manganese dioxide provided in Examples 1 to 4 of the present invention.

[0026] Figure 2 The images show the XRD patterns of manganese dioxide obtained in Examples 1 to 12 of this invention.

[0027] Figure 3 These are electron micrographs of the manganese dioxide obtained in Examples 1-12 of this invention, wherein... Figure 3 (a) is a SEM image of manganese dioxide; Figure 3 (b) is a TEM image of manganese dioxide.

[0028] Figure 4 The above are XPS analysis chromatograms of manganese dioxide obtained in Examples 1-12 of this invention. Figure 4 (a) is the Mn 3s diagram of manganese dioxide. Figure 4 (b) is the O1s diagram of manganese dioxide.

[0029] Figure 5 This is a diagram showing the cobalt and nickel recovery capacity of manganese dioxide prepared in Examples 1-12 of this invention, wherein... Figure 5 (a) is a graph showing the recovery capacity of α-MnO2 for cobalt and nickel obtained in Examples 1-4. Figure 5 (b) is a graph showing the recovery capacity of β-MnO2 for cobalt and nickel obtained in Examples 5-12. Figure 5 (c) is a diagram showing the recovery capacity of cobalt and nickel of γ-MnO2 prepared in Examples 5 to 12. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0032] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0033] This invention provides a method for preparing tunnel-type manganese dioxide, comprising the following steps:

[0034] S1. Mix the manganese precursor and the oxidant in a solvent to obtain a mixed solution; the manganese precursor includes manganese sulfate, the oxidant includes ammonium persulfate and / or potassium permanganate, and the ratio of manganese precursor: oxidant: solvent is 10-30 mmol: 10-60 mmol: 50-70 ml.

[0035] The main function of manganese precursors is to provide a manganese source, providing manganese ions (Mn). 2+ As a starting material for the synthesis of manganese dioxide, it promotes the nucleation and crystal growth of manganese dioxide. Since potassium permanganate, an oxidant, also contains manganese, it can also act as a manganese precursor, providing a manganese source and promoting the nucleation and crystal growth of manganese dioxide.

[0036] The manganese precursor and oxidant are mixed in a solvent, and the solvent's dispersing effect allows for more thorough contact between the two.

[0037] For example, the solvent can be water.

[0038] Specifically, the manganese precursor and oxidant can be placed in a solvent and stirred for at least 30 minutes to obtain a mixed solution. Magnetic stirring can be used for stirring.

[0039] In some embodiments, the preparation of β-MnO2 includes: the manganese precursor: the oxidant: the solvent in a ratio of 10-30 mmol: 10-40 mmol: 50-70 ml, wherein the manganese precursor is manganese sulfate and the oxidant is ammonium persulfate.

[0040] The preparation of γ-MnO2 includes: manganese precursor: oxidant: solvent = 10-30 mmol: 10-40 mmol: 50-70 ml, wherein the manganese precursor is manganese sulfate and the oxidant is ammonium persulfate.

[0041] The preparation of α-MnO2 includes: manganese precursor: oxidant: solvent = 10-30 mmol: 20-60 mmol: 50-70 ml, wherein the manganese precursor is manganese sulfate and the oxidant is potassium permanganate.

[0042] S2. Adjust the pH of the mixed solution to acidic, and then perform a hydrothermal reaction to obtain tunnel-type manganese dioxide; the tunnel-type manganese dioxide includes β-MnO2, γ-MnO2 and α-MnO2.

[0043] Specifically, the β-MnO2 is in the form of nanorods with a size structure of [1x1]; the γ-MnO2 is in the form of microspheres with a size structure of [1x2]; and the α-MnO2 is in the form of nanoneedles with a size structure of [2x2].

[0044] Where [XxX] is a crystal structure representation, referring to the basic unit of the crystal lattice. For example, the β-MnO2 size structure is [1x1], representing the number of octahedral edges in its octahedral tunnel structure.

[0045] In some embodiments, adjusting the pH of the mixed solution to acidic conditions includes: adding an acid solution to the mixed solution to adjust the pH of the mixed solution to 2-5; wherein the concentration of the acid solution is 0.1-1 mol / L, and the acid solution includes nitric acid.

[0046] In other embodiments, the preparation of β-MnO2 includes adjusting the pH of the mixed solution to 2-4 with the acid solution.

[0047] The preparation of γ-MnO2 includes: adjusting the pH of the mixed solution to 2-4 with the acid solution.

[0048] The preparation of α-MnO2 includes: adjusting the pH of the mixed solution to 3-5 with the acid solution.

[0049] In some embodiments, the reaction temperature of the hydrothermal reaction is 70–160°C, the heating time of the hydrothermal reaction is 10–40 min, the holding time of the hydrothermal reaction is 8–32 h, and the pressure of the hydrothermal reaction is 0.1–0.15 MPa.

[0050] Specifically, the preparation of β-MnO2 includes: the hydrothermal reaction temperature is 120-160℃, the hydrothermal reaction heating time is 20-40 min, and the hydrothermal reaction time is 8-16 h.

[0051] The preparation of γ-MnO2 includes: the hydrothermal reaction temperature is 70-110℃, the heating time of the hydrothermal reaction is 10-30 min, and the reaction time is 16-32 h.

[0052] The preparation of α-MnO2 includes a hydrothermal reaction at a temperature of 80-120℃, a heating time of 20-30 min, and a holding time of 16-32 h.

[0053] Specifically, the mixed solution can be placed in a polytetrafluoroethylene-lined reactor and placed in a constant-temperature oven for a high-temperature, high-pressure hydrothermal reaction. The principle of synthesizing MnO2 involves redox reactions and crystallization processes. The manganese salt solution needs to undergo a redox reaction, through permanganate (MnO4). - Or persulfate (S₂O₈) 2- Mn 2+ Completely oxidize and suspend it in the solution as solid particles.

[0054] For example, a high-temperature thermocouple oven can be used for high-temperature and high-pressure hydrothermal reactions.

[0055] By adaptively adjusting the raw material ratios, pH of the mixed solution, and hydrothermal reaction conditions of the manganese oxides with different structures, the crystal formation pathway can be optimized and controlled, enabling the precise formation of β-MnO2, γ-MnO2, and α-MnO2.

[0056] In some embodiments, the prepared tunnel-type manganese dioxide can be washed and dried.

[0057] The washing method can use deionized water, and the number of washes is 3 to 5.

[0058] The drying method can be high-vacuum drying, with a drying temperature of 60-80℃ and a drying vacuum level of 50-500 Pa. Under these conditions, the drying process can be effectively controlled to obtain the desired crystal structure and properties. Specifically, this condition prevents phase transformation caused by excessively high temperatures, and the vacuum level facilitates better removal of moisture and solvents from the sample without causing crystal damage or tunnel structure collapse.

[0059] Compared with the prior art, the present invention has at least the following advantages:

[0060] This invention provides a method for preparing tunnel-type manganese dioxide. An acidic solution combined with high-pressure solvothermal treatment creates an excellent nucleation and growth environment, allowing the manganese precursor and oxidant to rapidly oxidize and reduce, forming manganese oxide crystals of a specific size. The main reactions are as follows:

[0061] When manganese sulfate and ammonium persulfate react hydrothermally under high temperature and high acid conditions (120–160℃, pH 2–4) for 8–16 hours:

[0062] 2MnSO4+(NH4)2S2O8→2β-MnO2+(NH4)2SO4+H2SO4

[0063] When manganese sulfate and ammonium persulfate undergo a hydrothermal reaction under high temperature and high acid conditions (70–110℃, pH 2–4) for 16–32 hours:

[0064] 2MnSO4+(NH4)2S2O8→2γ-MnO2+(NH4)2SO4+H2SO4

[0065] When manganese sulfate and potassium permanganate undergo a hydrothermal reaction at high temperature and high acidity (80–120℃, pH 3–5) for 16–32 hours:

[0066] 2KMnO4+3MnSO4→5α-MnO2+K2SO4

[0067] This invention utilizes the different morphologies of β-MnO2, γ-MnO2, and α-MnO2 to specifically address the needs of different cobalt-nickel environments. For example, β-MnO2 has the smallest [1x1] size structure, which can expel most of the cobalt-nickel ions through its own nanotunneling effect; α-MnO2 has a larger [2x2] size structure and possesses excellent cobalt-nickel ion holding capacity.

[0068] In addition, based on the nanotunnel structure of tunnel-type manganese dioxide, β-MnO2, γ-MnO2, and α-MnO2 possess strong nanoconfinement effects, which can restrict the entry of large molecular solvents and other large-sized substances, thereby increasing the contact between cobalt / nickel and manganese oxide. Simultaneously, the bond length of the cobalt / nickel adsorbate decreases, and the reaction structure is enhanced, further promoting the stability of the adsorption-bound product. In contrast, the application of layered inorganic materials in the adsorption of cobalt / nickel in commonly used technologies mostly utilizes interlayer charged ions for cobalt / nickel ion exchange to achieve the adsorption-bound effect; however, as a weak binding method, the cobalt / nickel adsorbates obtained by ion exchange are prone to re-dissolution and leaching, and the adsorption effect is not stable.

[0069] The present invention also provides a tunnel-type manganese dioxide, which is prepared by any of the preparation methods described above, wherein the tunnel-type manganese dioxide comprises β-MnO2, γ-MnO2 and α-MnO;

[0070] The β-MnO2 is in the form of nanorods with a size structure of [1x1]; the γ-MnO2 is in the form of microspheres with a size structure of [1x2]; and the α-MnO2 is in the form of nanoneedles with a size structure of [2x2].

[0071] This invention provides a method for preparing tunnel-type manganese dioxide as described above, or the application of tunnel-type manganese dioxide as described above in the adsorption of cobalt and nickel, wherein the adsorption of cobalt and nickel is carried out in an acidic environment.

[0072] Specifically, the pH of the acidic environment can be 1 to 6.

[0073] For example, the pH of an acidic environment is 6.

[0074] In some embodiments, MnO2 with different pore sizes can be added to acidic waste liquid containing cobalt and nickel ions and recycled for 5-240 minutes, thereby realizing the application of tunnel-type manganese dioxide in cobalt and nickel adsorption.

[0075] For example, the recycling time can be 120 minutes.

[0076] In other embodiments, the initial cobalt concentration in the acidic waste liquid containing cobalt and nickel ions is 10-30 mg / L, the initial nickel concentration is 10-30 mg / L, and the dosage concentration of the tunnel-type manganese dioxide of different sizes is ≤0.5 g / L.

[0077] To further specify, the cobalt concentration in the cobalt and nickel waste liquid is 10 mg / L, the nickel concentration in the cobalt and nickel waste liquid is 10 mg / L, and the concentration of the tunnel-type manganese dioxide is 0.5 g / L.

[0078] To facilitate a further understanding of the present invention by those skilled in the art, the following examples are provided:

[0079] It should be noted that the different tunnel-type manganese dioxide in Examples 1-4 and Comparative Examples 1-8 include β-MnO2 with a size structure of [1x1], γ-MnO2 with a size structure of [1x2], and α-MnO2 with a size structure of [2x2].

[0080] In Examples 1-4, different methods for preparing tunnel-type manganese dioxide were used to obtain a mixed solution by mixing a manganese precursor, nitric acid, and an oxidant. The mixed solution was subjected to a high-pressure hydrothermal reaction under different parameter conditions to prepare tunnel-type manganese dioxide with different sizes.

[0081] The schematic diagrams of the process-mechanism for the recovery of cobalt and nickel ions from different tunnel-type manganese dioxide provided in Examples 1-4 are as follows: Figure 1 As shown.

[0082] Example 1

[0083] 1. First, add 60 mL of water to a beaker, then add 20 mmol of manganese sulfate and 40 mmol of potassium permanganate. Stir and mix thoroughly for at least 30 minutes to obtain a mixed solution. Adjust the pH of the mixed solution to 4 using 0.1 M nitric acid.

[0084] 2. Place the mixed solution into a polytetrafluoroethylene-lined reactor and place it in a constant temperature oven for a high-temperature and high-pressure hydrothermal reaction. Set the reaction temperature to 100℃, the heating time to 30 min, and the reaction time to 12 h.

[0085] 3. After the reaction apparatus cools, α-MnO2 is obtained by centrifugation. The obtained α-MnO2 is washed with deionized water four times. The obtained α-MnO2 is then dried under high vacuum at a temperature of 80℃ and a vacuum of 5000Pa.

[0086] 4. Using tunnel-type manganese dioxide of different sizes obtained above, cobalt and nickel ions are recovered from the acidic electrolyte. The initial cobalt concentration in the acidic electrolyte is 10 mg / L, the initial nickel concentration is 10 mg / L, the dosage of the tunnel-type manganese dioxide of different sizes is 0.5 g / L, and the pH of the acidic electrolyte is 3.

[0087] 5. After the recovery is completed, solid-liquid separation is performed, the solution is recovered, and the cobalt and nickel content is determined by ICP-OES.

[0088] Ultimately, the recovery rates of cobalt and nickel from the obtained α-MnO2 were 3164 μg / g and 1030 μg / g, respectively.

[0089] Example 2

[0090] Compared to Example 1, only step 4 is changed; that is, the following is changed:

[0091] 1. First, add 60 mL of water to a beaker, then add 20 mmol of manganese sulfate and 40 mmol of potassium permanganate. Stir and mix thoroughly for at least 30 minutes to obtain a mixed solution. Adjust the pH of the mixed solution to 4 using 0.1 M nitric acid.

[0092] 2. Place the mixed solution into a polytetrafluoroethylene-lined reactor and place it in a constant temperature oven for a high-temperature and high-pressure hydrothermal reaction. Set the reaction temperature to 100℃, the heating time to 30 min, and the reaction time to 12 h.

[0093] 3. After the reaction apparatus cools, α-MnO2 is obtained by centrifugation. The obtained α-MnO2 is washed with deionized water four times. The obtained α-MnO2 is then dried under high vacuum at a temperature of 80℃ and a vacuum of 5000Pa.

[0094] 4. Using tunnel-type manganese dioxide of different sizes obtained above to recover cobalt and nickel ions from acidic electrolyte, wherein the initial cobalt concentration in the acidic electrolyte is 10 mg / L, the initial nickel concentration is 10 mg / L, the dosage of the tunnel-type manganese dioxide of different sizes is 0.5 g / L, and the pH of the acidic electrolyte is 4.

[0095] 5. After the recovery is completed, solid-liquid separation is performed, the solution is recovered, and the cobalt and nickel content is determined by ICP-OES.

[0096] Ultimately, the recovery rates of cobalt and nickel from the obtained α-MnO2 were 3492 μg / g and 1524 μg / g, respectively.

[0097] Example 3

[0098] Compared to Example 1, only step 4 is changed; that is:

[0099] 1. First, add 60 mL of water to a beaker, then add 20 mmol of manganese sulfate and 40 mmol of potassium permanganate. Stir and mix thoroughly for at least 30 minutes to obtain a mixed solution. Adjust the pH of the mixed solution to 4 using 0.1 M nitric acid.

[0100] 2. Place the mixed solution into a polytetrafluoroethylene-lined reactor and place it in a constant temperature oven for a high-temperature and high-pressure hydrothermal reaction. Set the reaction temperature to 100℃, the heating time to 30 min, and the reaction time to 12 h.

[0101] 3. After the reaction apparatus cools, α-MnO2 is obtained by centrifugation. The obtained α-MnO2 is washed with deionized water four times. The obtained α-MnO2 is then dried under high vacuum at a temperature of 80℃ and a vacuum of 5000Pa.

[0102] 4. Using tunnel-type manganese dioxide of different sizes obtained above, cobalt and nickel ions are recovered from the acidic electrolyte. The initial cobalt concentration in the acidic electrolyte is 10 mg / L, the initial nickel concentration is 10 mg / L, the dosage of the tunnel-type manganese dioxide of different sizes is 0.5 g / L, and the pH of the acidic electrolyte is 5.

[0103] 5. After the recovery is completed, solid-liquid separation is performed, the solution is recovered, and the cobalt and nickel content is determined by ICP-OES.

[0104] Ultimately, the recovery rates of cobalt and nickel from the obtained α-MnO2 were 3420 μg / g and 1696 μg / g, respectively.

[0105] Example 4

[0106] Compared to Example 1, only step 4 is changed; that is:

[0107] 1. First, add 60 mL of water to a beaker, then add 20 mmol of manganese sulfate and 40 mmol of potassium permanganate. Stir and mix thoroughly for at least 30 minutes to obtain a mixed solution. Adjust the pH of the mixed solution to 4 using 0.1 M nitric acid.

[0108] 2. Place the mixed solution into a polytetrafluoroethylene-lined reactor and place it in a constant temperature oven for a high-temperature and high-pressure hydrothermal reaction. Set the reaction temperature to 100℃, the heating time to 30 min, and the reaction time to 12 h.

[0109] 3. After the reaction apparatus cools, α-MnO2 is obtained by centrifugation. The obtained α-MnO2 is washed with deionized water four times. The obtained α-MnO2 is then dried under high vacuum at a temperature of 80℃ and a vacuum of 5000Pa.

[0110] 4. Using tunnel-type manganese dioxide of different sizes obtained above to recover cobalt and nickel ions from acidic electrolyte, wherein the initial cobalt concentration in the acidic electrolyte is 10 mg / L, the initial nickel concentration is 10 mg / L, the dosage of the tunnel-type manganese dioxide of different sizes is 0.5 g / L, and the pH of the acidic electrolyte is 6.

[0111] 5. After the recovery is completed, solid-liquid separation is performed, the solution is recovered, and the cobalt and nickel content is determined by ICP-OES.

[0112] Ultimately, the recovery rates of cobalt and nickel from α-MnO2 were 3302 μg / g and 1226 μg / g, respectively.

[0113] Example 5

[0114] 1. First, add 60 mL of water to a beaker, then add 20 mmol of manganese sulfate and 25 mmol of ammonium persulfate, and stir and mix thoroughly for at least 30 minutes to obtain a mixed solution. Adjust the pH of the mixed solution to 3 using 0.1 M nitric acid.

[0115] 2. Place the mixed solution into a polytetrafluoroethylene-lined reactor and place it in a constant temperature oven for a high-temperature and high-pressure hydrothermal reaction. Set the reaction temperature to 140℃, the heating time to 30 min, and the reaction time to 12 h.

[0116] 3. After the reaction apparatus has cooled, β-MnO2 is obtained by centrifugation. The obtained β-MnO2 is washed with deionized water four times. The obtained β-MnO2 is then dried under high vacuum at a temperature of 80℃ and a vacuum of 500Pa.

[0117] 4. Using tunnel-type manganese dioxide of different sizes obtained above, cobalt and nickel ions are recovered from the acidic electrolyte. The initial cobalt concentration in the acidic electrolyte is 10 mg / L, the initial nickel concentration is 10 mg / L, the dosage of the tunnel-type manganese dioxide of different sizes is 0.5 g / L, and the pH of the acidic electrolyte is 3.

[0118] 5. After the recovery is completed, solid-liquid separation is performed, the solution is recovered, and the cobalt and nickel content is determined by ICP-OES.

[0119] Ultimately, the recovery rates of cobalt and nickel from β-MnO2 were 2102 μg / g and 536 μg / g, respectively.

[0120] Example 6

[0121] Compared to Example 5, only step 4 is changed; that is:

[0122] 1. First, add 60 mL of water to a beaker, then add 20 mmol of manganese sulfate and 25 mmol of ammonium persulfate, and stir and mix thoroughly for at least 30 minutes to obtain a mixed solution. Adjust the pH of the mixed solution to 3 using 0.1 M nitric acid.

[0123] 2. Place the mixed solution into a polytetrafluoroethylene-lined reactor and place it in a constant temperature oven for a high-temperature and high-pressure hydrothermal reaction. Set the reaction temperature to 140℃, the heating time to 30 min, and the reaction time to 12 h.

[0124] 3. After the reaction apparatus has cooled, β-MnO2 is obtained by centrifugation. The obtained β-MnO2 is washed with deionized water four times. The obtained β-MnO2 is then dried under high vacuum at a temperature of 80℃ and a vacuum of 500Pa.

[0125] 4. Using tunnel-type manganese dioxide of different sizes obtained above to recover cobalt and nickel ions from acidic electrolyte, wherein the initial cobalt concentration in the acidic electrolyte is 10 mg / L, the initial nickel concentration is 10 mg / L, the dosage of the tunnel-type manganese dioxide of different sizes is 0.5 g / L, and the pH of the acidic electrolyte is 4.

[0126] 5. After the recovery is completed, solid-liquid separation is performed, the solution is recovered, and the cobalt and nickel content is determined by ICP-OES.

[0127] Ultimately, the recovery rates of cobalt and nickel from the obtained β-MnO2 were 2164 μg / g and 910 μg / g, respectively.

[0128] Example 7

[0129] Compared to Example 5, only step 4 is changed; that is:

[0130] 1. First, add 60 mL of water to a beaker, then add 20 mmol of manganese sulfate and 25 mmol of ammonium persulfate, and stir and mix thoroughly for at least 30 minutes to obtain a mixed solution. Adjust the pH of the mixed solution to 3 using 0.1 M nitric acid.

[0131] 2. Place the mixed solution into a polytetrafluoroethylene-lined reactor and place it in a constant temperature oven for a high-temperature and high-pressure hydrothermal reaction. Set the reaction temperature to 140℃, the heating time to 30 min, and the reaction time to 12 h.

[0132] 3. After the reaction apparatus has cooled, β-MnO2 is obtained by centrifugation. The obtained β-MnO2 is washed with deionized water four times. The obtained β-MnO2 is then dried under high vacuum at a temperature of 80℃ and a vacuum of 500Pa.

[0133] 4. Using tunnel-type manganese dioxide of different sizes obtained above, cobalt and nickel ions are recovered from the acidic electrolyte. The initial cobalt concentration in the acidic electrolyte is 10 mg / L, the initial nickel concentration is 10 mg / L, the dosage of the tunnel-type manganese dioxide of different sizes is 0.5 g / L, and the pH of the acidic electrolyte is 5.

[0134] 5. After the recovery is completed, solid-liquid separation is performed, the solution is recovered, and the cobalt and nickel content is determined by ICP-OES.

[0135] Ultimately, the recovery rates of cobalt and nickel from the obtained β-MnO2 were 2360 μg / g and 900 μg / g, respectively.

[0136] Example 8

[0137] Compared to Example 5, only step 4 is changed; that is:

[0138] 1. First, add 60 mL of water to a beaker, then add 20 mmol of manganese sulfate and 25 mmol of ammonium persulfate, and stir and mix thoroughly for at least 30 minutes to obtain a mixed solution. Adjust the pH of the mixed solution to 3 using 0.1 M nitric acid.

[0139] 2. Place the mixed solution into a polytetrafluoroethylene-lined reactor and place it in a constant temperature oven for a high-temperature and high-pressure hydrothermal reaction. Set the reaction temperature to 140℃, the heating time to 30 min, and the reaction time to 12 h.

[0140] 3. After the reaction apparatus has cooled, β-MnO2 is obtained by centrifugation. The obtained β-MnO2 is washed with deionized water four times. The obtained β-MnO2 is then dried under high vacuum at a temperature of 80℃ and a vacuum of 500Pa.

[0141] 4. Using tunnel-type manganese dioxide of different sizes obtained above to recover cobalt and nickel ions from acidic electrolyte, wherein the initial cobalt concentration in the acidic electrolyte is 10 mg / L, the initial nickel concentration is 10 mg / L, the dosage of the tunnel-type manganese dioxide of different sizes is 0.5 g / L, and the pH of the acidic electrolyte is 6.

[0142] 5. After the recovery is completed, solid-liquid separation is performed, the solution is recovered, and the cobalt and nickel content is determined by ICP-OES.

[0143] Ultimately, the recovery rates of cobalt and nickel from the obtained β-MnO2 were 2140 μg / g and 586 μg / g, respectively.

[0144] Example 9

[0145] Compared to Example 5, only steps 2 and 3 are changed; that is:

[0146] 1. First, add 60 mL of water to a beaker, then add 20 mmol of manganese sulfate and 25 mmol of ammonium persulfate, and stir and mix thoroughly for at least 30 minutes to obtain a mixed solution. Adjust the pH of the mixed solution to 3 using 0.1 M nitric acid.

[0147] 2. Place the mixed solution into a polytetrafluoroethylene-lined reactor and place it in a constant temperature oven for a high-temperature and high-pressure hydrothermal reaction. Set the reaction temperature to 90℃, the heating time to 30 min, and the reaction time to 24 h.

[0148] 3. After the reaction apparatus cools, γ-MnO2 is obtained by centrifugation. The obtained γ-MnO2 is washed four times with deionized water. The γ-MnO2 is then dried under high vacuum at 60℃ and a vacuum of 5000 Pa. The relatively low drying temperature and pressure of γ-MnO2 are closer to atmospheric pressure because γ-MnO2, as a transition phase (metastable phase), can transform into the more stable β-MnO2 under high-temperature conversion or even natural aging conditions. Therefore, the drying temperature and vacuum are more moderate to minimize damage to its crystal structure.

[0149] 4. Using tunnel-type manganese dioxide of different sizes obtained above, cobalt and nickel ions are recovered from the acidic electrolyte. The initial cobalt concentration in the acidic electrolyte is 10 mg / L, the initial nickel concentration is 10 mg / L, the dosage of the tunnel-type manganese dioxide of different sizes is 0.5 g / L, and the pH of the acidic electrolyte is 3.

[0150] 5. After the recovery is completed, solid-liquid separation is performed, the solution is recovered, and the cobalt and nickel content is determined by ICP-OES.

[0151] Ultimately, the recovery rates of cobalt and nickel from the obtained γ-MnO2 were 2378 μg / g and 612 μg / g, respectively.

[0152] Example 10

[0153] Compared to Example 9, only step 4 is changed; that is:

[0154] 1. First, add 60 mL of water to a beaker, then add 20 mmol of manganese sulfate and 25 mmol of ammonium persulfate, and stir and mix thoroughly for at least 30 minutes to obtain a mixed solution. Adjust the pH of the mixed solution to 3 using 0.1 M nitric acid.

[0155] 2. Place the mixed solution into a polytetrafluoroethylene-lined reactor and place it in a constant temperature oven for a high-temperature and high-pressure hydrothermal reaction. Set the reaction temperature to 90℃, the heating time to 30 min, and the reaction time to 24 h.

[0156] 3. After the reaction apparatus has cooled, γ-MnO2 is obtained by centrifugation. The obtained γ-MnO2 is washed with deionized water four times. The obtained γ-MnO2 is then dried under high vacuum at a temperature of 60℃ and a vacuum of 5000Pa.

[0157] 4. Using tunnel-type manganese dioxide of different sizes obtained above to recover cobalt and nickel ions from acidic electrolyte, wherein the initial cobalt concentration in the acidic electrolyte is 10 mg / L, the initial nickel concentration is 10 mg / L, the dosage of the tunnel-type manganese dioxide of different sizes is 0.5 g / L, and the pH of the acidic electrolyte is 4.

[0158] 5. After the recovery is completed, solid-liquid separation is performed, the solution is recovered, and the cobalt and nickel content is determined by ICP-OES.

[0159] Ultimately, the recovery rates of cobalt and nickel from the obtained γ-MnO2 were 2270 μg / g and 1038 μg / g, respectively.

[0160] Example 11

[0161] Compared to Example 9, only step 4 is changed; that is:

[0162] 1. First, add 60 mL of water to a beaker, then add 20 mmol of manganese sulfate and 25 mmol of ammonium persulfate, and stir and mix thoroughly for at least 30 minutes to obtain a mixed solution. Adjust the pH of the mixed solution to 3 using 0.1 M nitric acid.

[0163] 2. Place the mixed solution into a polytetrafluoroethylene-lined reactor and place it in a constant temperature oven for a high-temperature and high-pressure hydrothermal reaction. Set the reaction temperature to 90℃, the heating time to 30 min, and the reaction time to 24 h.

[0164] 3. After the reaction apparatus has cooled, γ-MnO2 is obtained by centrifugation. The obtained γ-MnO2 is washed with deionized water four times. The obtained γ-MnO2 is then dried under high vacuum at a temperature of 60℃ and a vacuum of 5000Pa.

[0165] 4. Using tunnel-type manganese dioxide of different sizes obtained above to recover cobalt and nickel ions from acidic electrolyte, wherein the initial cobalt concentration in the acidic electrolyte is 10 mg / L, the initial nickel concentration is 10 mg / L, the dosage of the tunnel-type manganese dioxide of different sizes is 0.5 g / L, and the pH of the acidic electrolyte is 5.

[0166] 5. After the recovery is completed, solid-liquid separation is performed, the solution is recovered, and the cobalt and nickel content is determined by ICP-OES.

[0167] Ultimately, the recovery rates of cobalt and nickel from the obtained γ-MnO2 were 2282 μg / g and 964 μg / g, respectively.

[0168] Example 12

[0169] Compared to Example 9, only step 4 is changed; that is:

[0170] 1. First, add 60 mL of water to a beaker, then add 20 mmol of manganese sulfate and 25 mmol of ammonium persulfate, and stir and mix thoroughly for at least 30 minutes to obtain a mixed solution. Adjust the pH of the mixed solution to 3 using 0.1 M nitric acid.

[0171] 2. Place the mixed solution into a polytetrafluoroethylene-lined reactor and place it in a constant temperature oven for a high-temperature and high-pressure hydrothermal reaction. Set the reaction temperature to 90℃, the heating time to 30 min, and the reaction time to 24 h.

[0172] 3. After the reaction apparatus has cooled, γ-MnO2 is obtained by centrifugation. The obtained γ-MnO2 is washed with deionized water four times. The obtained γ-MnO2 is then dried under high vacuum at a temperature of 60℃ and a vacuum of 5000Pa.

[0173] 4. Using tunnel-type manganese dioxide of different sizes obtained above to recover cobalt and nickel ions from acidic electrolyte, wherein the initial cobalt concentration in the acidic electrolyte is 10 mg / L, the initial nickel concentration is 10 mg / L, the dosage of the tunnel-type manganese dioxide of different sizes is 0.5 g / L, and the pH of the acidic electrolyte is 6.

[0174] 5. After the recovery is completed, solid-liquid separation is performed, the solution is recovered, and the cobalt and nickel content is determined by ICP-OES.

[0175] Ultimately, the recovery rates of cobalt and nickel from the obtained γ-MnO2 were 2340 μg / g and 636 μg / g, respectively.

[0176] Analysis example 1

[0177] Characterization analysis of manganese dioxide used in Examples 1-12

[0178] 1. The XRD crystal structure of the manganese dioxide was analyzed, and the results are as follows: Figure 2 As shown. According to Figure 2 Observations show that the crystals of manganese dioxide synthesized by this method are very close to the corresponding peak positions and intensities in the standard PDF card. This indicates that the samples prepared by this method have similar crystal structures and phase compositions to the known α, β, and γ manganese dioxide structures. Among them, the α-MnO2

[211] crystal plane, β-MnO2

[110] crystal plane, and δ-MnO2

[131] crystal plane are the dominant crystal planes. Given that the α, β, and γ manganese dioxide samples prepared by this method show good agreement with the standard crystal structure and phase composition, further research and application of this material is of great significance.

[0179] 2. The morphology of the manganese dioxide was analyzed by electron microscopy, and the results are as follows: Figure 3 As shown, (a) is a SEM image of manganese dioxide; (b) is a TEM image of manganese dioxide. According to... Figure 3 Observations revealed that α-MnO2 is in the form of nanoneedles with a particle size generally distributed between 100-1000 nm; β-MnO2 is in the form of nanoneedles with a particle size generally distributed between 200-800 nm; and γ-MnO2 is in the form of aggregated micron-sized spheres with a particle size distributed between 5-10 μm.

[0180] 3. The manganese dioxide was analyzed by XPS, and the results are as follows: Figure 4 As shown, (a) is the Mn3s diagram of manganese dioxide; (b) is the O1s diagram of manganese dioxide. According to... Figure 4(a) The average oxidation state (AOS) of Mn was calculated using Mn 3s, revealing that α-MnO2 was 3.59, β-MnO2 was 3.80, and γ-MnO2 was 3.80, demonstrating that β-MnO2 has a more complete crystal structure and fewer oxygen vacancies; this is also evident from... Figure 4 (b) It can be verified that the oxygen defect peak of β-MnO2 has the lowest relative intensity (27.91%).

[0181] Analysis example 2

[0182] Analysis of manganese leaching capacity and reduction rate of tetravalent manganese in the manganese-containing leachate obtained by the methods used in Examples 1-12

[0183] 1. Examples 1-4 illustrate the recovery capacity of α-MnO2 for cobalt and nickel as follows: Figure 5 As shown in (a). Figure 5 (a) Observations show that α-MnO2 has a cobalt recovery capacity of over 3000 μg / g and a nickel recovery capacity of over 1000 μg / g in all acidic ranges; among them, the cobalt recovery capacity of Example 2 is the best at 3492 μg / g and the nickel recovery capacity of Example 3 is the best at 1696 μg / g.

[0184] 2. Examples 5-12 illustrate the recovery capacities of β-MnO2 and γ-MnO2 for cobalt and nickel, as shown below. Figure 5 As shown in (b) and (c). Figure 5 (b) Observations show that the recovery capacity of β-MnO2 and γ-MnO2 for cobalt is difficult to reach 2500 μg / g across all pH ranges, and the recovery capacity for nickel is difficult to reach 1000 μg / g. This is mainly due to their narrow pore structure, which makes it difficult for the tunnels to accommodate cobalt and nickel hydrated ions with large radii. The above technical solutions of the present invention are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the specification and drawings of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. An application of tunnel-type manganese dioxide in the treatment of cobalt and nickel wastewater, characterized in that, Cobalt and nickel adsorption is carried out in an acidic environment with a pH of 3-6. The preparation of the tunnel-type manganese dioxide includes the following steps: A manganese precursor and an oxidant are mixed in a solvent to obtain a mixed solution; the ratio of the manganese precursor to the oxidant to the solvent is 20 mmol: 40 mmol: 60 ml; the manganese precursor is manganese sulfate and the oxidant is potassium permanganate. The pH of the mixed solution was adjusted to acidic, and tunnel-type manganese dioxide was obtained by hydrothermal reaction; the tunnel-type manganese dioxide is α~MnO2 with an average oxidation state of Mn of 3.59; the reaction temperature of the hydrothermal reaction is 100℃; the pH of the mixed solution is 4.

2. The application of tunnel-type manganese dioxide according to claim 1 in the treatment of cobalt and nickel wastewater, characterized in that, The α-MnO2 is in the form of nanoneedles with a size structure of [2x2].

3. The application of tunnel-type manganese dioxide according to claim 2 in the treatment of cobalt and nickel wastewater, characterized in that, The step of adjusting the pH of the mixed solution to acidic includes: adding an acid solution to the mixed solution to adjust the pH value of the mixed solution to 3-5; wherein the concentration of the acid solution is 0.1-1 mol / L, and the acid solution includes nitric acid.

4. The application of tunnel-type manganese dioxide according to claim 1 in the treatment of cobalt and nickel wastewater, characterized in that, The pressure of the hydrothermal reaction is 0.15 MPa.

5. The application of tunnel-type manganese dioxide according to claim 4 in the treatment of cobalt and nickel wastewater, characterized in that, The heating time for the hydrothermal reaction is 20-30 minutes, and the holding time for the hydrothermal reaction is 12 hours.

6. The application of tunnel-type manganese dioxide according to any one of claims 1 to 5 in the treatment of cobalt and nickel wastewater, characterized in that, The cobalt concentration in the cobalt and nickel waste liquid is 10~30 mg / L, the nickel concentration in the cobalt and nickel waste liquid is 10 mg / L, and the dosage concentration of the tunnel-type manganese dioxide is ≤0.5 g / L.

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