CN106044862A - Method for preparing nano-manganese oxide through low-temperature electrolysis - Google Patents

Abstract

The invention provides a low-temperature preparation method of nanometer electrolytic manganese dioxide, which belongs to the technical field of manganese dioxide preparation. The method uses a copper plate as a cathode and a graphite plate as an anode for electrolysis, the electrolysis temperature is 5-30°C, the anode current density is 100-1000A/m ² , the concentration of H ₂ SO ₄ in the electrolyte is 30-60g/L, MnSO ₄ The concentration is 40-70g/L, and the electrolytic MnO ₂ prepared is then left to stand, suction filtered (washed with water + alcohol), vacuum dried, and ground to obtain a finished nano-MnO ₂ product. The prepared nanometer _MnO2 is a spherical particle with a particle diameter of 50-200nm. Compared with other high-temperature electrolytic manganese dioxide (usually around 98°C), the product of the present invention is nano-sized γ-MnO ₂ with uniform particle size, and the conditions are mild, the production equipment is simple, the cost is lower, the electrolytic system is stable and controllable, and The treatment is simple and safe, the environmental pollution is small, the waste liquid can be recycled and electrolyzed, the current efficiency and operability are more considerable, and large-scale industrial production can be carried out.

Description

Method for preparing nano manganese dioxide by low temperature electrolysis

technical field

The invention belongs to the technical field of electrolytic manganese dioxide preparation, in particular to a method for preparing nano manganese dioxide by low-temperature electrolysis.

Background technique

Since the invention of dry batteries in 1888, manganese dioxide has been used as the main positive electrode material of dry batteries, and its performance has a decisive impact on the performance of zinc-manganese dry batteries. At present, the preparation methods of manganese dioxide mainly include chemical methods and electrolytic methods. The yield and purity of chemical manganese dioxide are high, but chemical manganese dioxide has the disadvantages of large average particle size, complicated operation, serious environmental pollution, non-continuous production, and unsuitability for industrial production. Electrolytic manganese dioxide, which has the advantages of large size, strong electrochemical activity, small size, and long life, can not only be used as an excellent battery depolarizer, but also can be used as a supercapacitor material, an oxidant in chemical production, lithium-ion batteries and The raw material of manganese zinc ferrite soft magnetic material is also an excellent water purification filter material, and its adsorption performance is better than activated carbon and zeolite.

Compared with chemical manganese dioxide, the nano-electrolytic manganese dioxide produced by this method has basically the same chemical composition and crystal structure, and has the advantages of small and uniform particle size, small volume, large specific surface area, and good electrochemical activity. The rate is 92%, the 100-mesh product index is 90%, and the product purity is 95%. The nano electrolytic manganese dioxide produced by this method can be used as a battery raw material, and can also be widely used as an oxidation/reduction agent, catalyst, water purification filter material, etc. in fine chemical production. Most of the current electrolytic manganese dioxide methods on the market are high-temperature preparation of massive micron-sized manganese dioxide materials, which require high energy consumption and are difficult to handle. Controlling the electrolysis conditions can reduce the deposition of manganese dioxide on the electrode plate. In patent 201110171479.1, ultrasonic electrolysis is used, and a separator and additives are used at the same time to disperse manganese dioxide in the electrolyte as much as possible. In this patent, under the condition of no diaphragm, by controlling the low temperature and dispersant, the nucleation and growth mechanism of manganese dioxide is controlled, so that it is suspended in the electrolyte, and the product is nanometer γ-MnO ₂ with uniform particle size. The method has mild conditions, simple production equipment, high yield, stable and controllable electrolysis system, simple and safe treatment of waste liquid, less environmental pollution, recyclable electrolysis of waste liquid, and lower production cost. By studying the method of preparing nano-manganese dioxide by low-temperature electrolysis under appropriate temperature, appropriate current density, and high current efficiency, the cost of raw materials and electricity charges can be significantly reduced, the market competitiveness of enterprises can be improved, and energy conservation and environmental protection can be realized.

Contents of the invention

The object of the present invention is to: in view of the above-mentioned existing problems, provide a kind of method for preparing nano-manganese dioxide by low-temperature electrolysis, this method aims at using MnSO ₄ +H ₂ SO ₄ aqueous solution as electrolyte, copper plate as cathode, graphite plate as anode, The method for preparing nano-manganese dioxide by low-temperature electrolysis can significantly reduce the production cost of the enterprise, improve the market competitiveness of the enterprise, and realize energy saving and environmental protection.

In order to achieve the above object, the present invention adopts the following technical solutions:

A method for preparing nano-manganese dioxide by low-temperature electrolysis, the method comprising the following steps:

(1) Preparation of electrolyte: use industrial manganese sulfate as raw material, dissolve in deionized water, add concentrated sulfuric acid and a small amount of dispersant A according to a certain mass ratio, stir to form a uniform solution, and let it stand at room temperature for a period of time.

(2) Pretreatment: Use a water bath heating device to heat the electrolyte to keep the temperature of the solution at 5-30°C, and clean the two electrode plates.

(3) Electrolysis: Set up the electrolysis device and the inlet and outlet pipes, electrolyze the electrolyte, and precipitate manganese dioxide on the anode.

(4) Post-treatment: After electrolysis, clean the manganese dioxide on the graphite plate, let the electrolyte stand still, filter with suction (rinse with water and ethanol), collect the filtrate, continue electrolysis, and finally vacuum dry and grind to obtain Low-temperature electrolysis of nano-manganese dioxide finished products, and the filtrate continues to be electrolyzed.

In the electrolytic cell, copper plates are used as cathodes and graphite plates are used as anodes for electrolysis. The electrolysis temperature is 5-30°C, the anode current density is 100-1000A/m ² , and the concentration of H ₂ SO ₄ in the electrolyte is 30-50g/L. The concentration of MnSO ₄ is 40-60g/L.

More preferably, copper plates are used as cathodes, graphite plates are used as anodes for electrolysis, the electrolysis temperature is 5-30°C, the anode current density is _300-800A / ^m2 , the concentration of _H2SO4 in the electrolyte is 30-50g/L, MnSO ₄ The concentration is 40-60g/L.

Furthermore, the selected liquid inlet and outlet pipes are all on the side of the anode plate, and the appropriate flow rate is controlled through calculation.

The main reactions to produce electrolytic manganese dioxide are:

The main reaction on the anode is: Mn ²⁺ +2H ₂ O→MnO ₂ +4H ⁺ +2e ^- (E ₁ =1.23V)

The main reaction on the cathode is: 2H ⁺ +2e ^- → H ₂ ↑ (E ₂ =0V)

The total reaction that occurs during electrolysis is: MnSO ₄ +2H ₂ O→MnO ₂ +H ₂ SO ₄ +H ₂ ↑

The theoretical decomposition voltage is: E= E ₁ -E ₂ =1.23V

In summary, due to the adoption of the above technical scheme, the beneficial effects of the present invention are: the present invention achieves the purpose of preparing nano-manganese dioxide by low-temperature electrolysis by controlling the anode current density, electrolyte concentration, electrolysis temperature, electrode plate type and other technical means . While ensuring product quality, low-temperature electrolysis reduces the cost of electricity, reduces the deposition of manganese dioxide on the anode plate, increases the life of the anode, prolongs the electrolysis time, further reduces the production cost of the enterprise, improves its market competitiveness, and realizes energy conservation and environmental protection .

Description of drawings

Fig. 1 is the scanning electron micrograph of the nano-manganese dioxide finished product prepared by low-temperature electrolysis;

Fig. 2 is the XRD pattern of nano-manganese dioxide finished product prepared by low-temperature electrolysis;

Fig. 3 is the discharge curve of the lithium-manganese dioxide battery in which the nano-manganese dioxide finished product is prepared by low-temperature electrolysis.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings. The following embodiments are explanations of the present invention, and the present invention is not limited to the following embodiments.

Example 1:

Use industrial manganese sulfate as raw material, and the beaker is the electrolytic cell. In a 5L beaker, prepare 40±10g/L manganese sulfate with deionized water, slowly add concentrated sulfuric acid according to the mass ratio of 1:1, and stir to form a uniform solution. Stand still for a period of time, place the large beaker in a water bath, set the temperature at 5-10°C, and control the temperature of the electrolyte. Use graphite as the anode plate and copper plate as the cathode plate, and immerse the cathode and anode plates in the electrolyte solution at 5-10°C. Put 80±10g/L manganese sulfate replenishing solution in the hanging bottle, when the regulated DC power supply starts electrolysis at the current density of 100±10A/ ^m2 , replenish it on the side of the anode plate, and use the infusion solution at the same time The sulfuric acid produced in the electrolysis process was discharged through the pipe to ensure the stability of the acidity of the system, and the precipitation of manganese dioxide was observed, and the electrolysis was performed for 12 hours. After the electrolysis was stopped, the electrolyte solution was left to stand overnight, then suction filtered with a Buchner funnel, the filtrate was collected, rinsed twice with water and ethanol, dried in vacuum at 70°C, and the dried solid was ground in a quartz mortar to obtain Black nano manganese dioxide powder prepared by electrolysis. Weighing, productive rate is 30%, and product purity is 90%, and 100 mesh product indexs are 40%, are contained in sealing bag. The collected filtrate is then subjected to electrolysis.

Example 2:

Use industrial manganese sulfate as raw material, and the beaker is the electrolytic cell. In a 5L beaker, prepare 40±10g/L manganese sulfate with deionized water, slowly add concentrated sulfuric acid according to the mass ratio of 1:1, and stir to form a uniform solution. Stand still for a period of time, place the large beaker in a water bath, set the temperature at 10-20°C, and control the temperature of the electrolyte. Use graphite as the anode plate and copper plate as the cathode plate, and immerse the cathode and anode plates in the electrolyte solution at 10-20°C. Put 80±10g/L manganese sulfate replenishing solution in the hanging bottle, when the stabilized DC power supply starts electrolysis at the current density of ²⁰⁰ ±10A/m2, replenish it on the side of the anode plate, and use the infusion solution at the same time The sulfuric acid produced in the electrolysis process was discharged through the pipe to ensure the stability of the acidity of the system, and the precipitation of manganese dioxide was observed, and the electrolysis was performed for 12 hours. After the electrolysis was stopped, the electrolyte solution was left to stand overnight, then suction filtered with a Buchner funnel, the filtrate was collected, rinsed twice with water and ethanol, dried in vacuum at 70°C, and the dried solid was ground in a quartz mortar to obtain Black nano manganese dioxide powder prepared by electrolysis. Weighing, productive rate is 40%, and product purity is 90%, and 100 mesh product indexs are 50%, are contained in sealing bag. The collected filtrate is then subjected to electrolysis.

Example 3:

Use industrial manganese sulfate as raw material, and the beaker is the electrolytic cell. In a 5L beaker, prepare 40±10g/L manganese sulfate with deionized water, and slowly add concentrated sulfuric acid and a small amount of dispersant A according to the mass ratio of 1:1:0.05. , stirred to form a homogeneous solution, stood still at room temperature for a period of time, placed the large beaker in a water bath, set the temperature at 10-20°C, and controlled the temperature of the electrolyte. Use graphite as the anode plate and copper plate as the cathode plate, and immerse the cathode and anode plates in the electrolyte solution at 10-20°C. Put 80±10g/L manganese sulfate replenishing solution in the hanging bottle, when the stabilized DC power supply starts electrolysis at the current density of ²⁰⁰ ±10A/m2, replenish it on the side of the anode plate, and use the infusion solution at the same time The sulfuric acid produced in the electrolysis process was discharged through the pipe to ensure the stability of the acidity of the system, and the precipitation of manganese dioxide was observed, and the electrolysis was performed for 12 hours. After the electrolysis was stopped, the electrolyte solution was left to stand overnight, then suction filtered with a Buchner funnel, the filtrate was collected, rinsed twice with water and ethanol, dried in vacuum at 70°C, and the dried solid was ground in a quartz mortar to obtain Low-temperature electrolytic black nano manganese dioxide powder. Weighing, productive rate is 70%, and product purity is 90%, and 100 object product indexes are 70%, are contained in sealing bag. The collected filtrate is then subjected to electrolysis.

Example 4:

Use industrial manganese sulfate as raw material, and the beaker is the electrolytic cell. In a 5L beaker, prepare 40±10g/L manganese sulfate with deionized water, slowly add concentrated sulfuric acid and a small amount of dispersant A according to the mass ratio of 1:1:0.1, Stir to form a homogeneous solution, let stand at room temperature for a period of time, place the large beaker in a water bath, set the temperature at 20-30°C, and heat the electrolyte to the set temperature. Use graphite as the anode plate and copper plate as the cathode plate, and immerse the cathode and anode plates in the electrolyte solution at 20-30°C. Put 80±10g/L manganese sulfate replenishing solution in the hanging bottle, and when the regulated DC power supply starts electrolysis at the current density of ²⁰⁰ ±10A/m2, add it on the side of the anode plate, and at the same time On one side of the plate, discharge the sulfuric acid produced during the electrolysis process with an infusion tube to ensure that the acidity of the system is stable, observe the precipitation of manganese dioxide, and perform electrolysis for 12 hours. After the electrolysis was stopped, the electrolyte solution was left to stand overnight, then suction filtered with a Buchner funnel, the filtrate was collected, rinsed twice with water and ethanol, dried in vacuum at 70°C, and the dried solid was ground in a quartz mortar to obtain Black nano manganese dioxide powder prepared by electrolysis. Weighing, productive rate is 90%, and product purity is 95%, and 100 order product indexs are 85%, are contained in sealing bag. The collected filtrate is then subjected to electrolysis.

The above description is a detailed description of the feasible embodiments of the present invention, but the embodiments are not used to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit suggested by the present invention shall belong to the present invention The scope of patents covered.

Claims (10)

1. the method that low-temperature electrolytic prepares nano-manganese dioxide, it uses the following step:

With industrial manganic sulfate as raw material, according to certain mass ratio, adding concentrated sulphuric acid, and a small amount of dispersant A, stirring is formed uniformly Solution；At a certain temperature, it is electrolysed by electrolysis unit, prepares nano-manganese dioxide；After electrolysis terminates, process graphite cake The most a small amount of upper manganese dioxide, and suspension is carried out sucking filtration, washs, be dried, prepare nano-manganese dioxide.

The method that the most according to claim 1, low-temperature electrolytic prepares nano-manganese dioxide, it is characterised in that: manganese sulfate, sulphuric acid, The mass ratio of dispersant A is: 1:1～1.5:0.02～0.1.

The method that the most according to claim 1, low-temperature electrolytic prepares nano-manganese dioxide, it is characterised in that: dispersant A is poly- Vinyl pyrrolidone, dodecyl sodium sulfate and Dodecyl trimethyl ammonium chloride etc..

The method that the most according to claim 1, low-temperature electrolytic prepares nano-manganese dioxide, it is characterised in that: copper coin is negative electrode, Graphite cake is anode, and electrolysis temperature is 5～30 DEG C, and anodic current density is 100～1000A/m², H in electrolyte₂SO₄Dense Degree is 40～60g/L, MnSO₄Concentration is 40～60g/L, MnSO₄Adding liquid concentration is MnSO in electrolyte₄The 2 of concentration Times, tank voltage is 2.0～8.0V, and electrolysing period is 2～10 days.

The method that the most according to claim 2, low-temperature electrolytic prepares nano-manganese dioxide, it is characterised in that: minus plate and anode The spacing of plate is 8～15cm.

The method that the most according to claim 2, low-temperature electrolytic prepares nano-manganese dioxide, it is characterised in that: selected enter, Drain pipe, all in positive plate side.

The method that the most according to claim 2, low-temperature electrolytic prepares nano-manganese dioxide, it is characterised in that: pass through liquid inlet and outlet Pipe, can control sulphuric acid and manganese sulfate concentration in solution, carry out continuous electrolysis, and electrolysis time can extend to 280h.

The method that the most according to claim 2, low-temperature electrolytic prepares nano-manganese dioxide, it is characterised in that: electrolysis terminates, and Time process graphite cake and copper coin.

The method that the most according to claim 2, low-temperature electrolytic prepares nano-manganese dioxide, it is characterised in that: the titanium dioxide of preparation Manganese is nanoscale manganese dioxide, and dispersion effect is good in the electrolytic solution, and particle diameter is 50-200nm.

The method that the most according to claim 2, low-temperature electrolytic prepares nano-manganese dioxide, it is characterised in that: the dioxy of preparation Changing manganese is γ-MnO₂。