Spherical large-specific-surface-area nano-zinc oxide and preparation method thereof

Abstract

The invention belongs to the technical field of nano materials, and discloses spherical large-specific-surface-area nano zinc oxide and a preparation method thereof. Firstly, the zinc-containing mineral is subjected to acid leaching purification, and a zinc sulfate solution is obtained; then, reacting the zinc sulfate solution with a precipitator, and synthesizing basic zinc carbonate precursor slurry by using a multi-phase interface reactor; and finally, washing, drying and calcining the basic zinc carbonate precursor to obtain the nano zinc oxide powder. The prepared nano zinc oxide product is white powder, is of a spherical structure, and is large in specific surface area, good in monodispersity and small in particle size.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterials, and particularly relates to a spherical nano zinc oxide with a large specific surface area and a preparation method thereof. Background Art

[0002] Nano zinc oxide is a multifunctional inorganic material. Due to its surface and interface effect, quantum size effect, volume effect, macroscopic quantum tunneling effect, as well as high transparency, high dispersibility, ultraviolet shielding and other characteristics, it shows many unique and excellent physical and chemical properties in chemistry, optics, biology and electricity, etc. It has special properties and uses that cannot be compared with ordinary zinc oxide, and has extensive applications in industries such as rubber, coatings, plastics, ceramics, catalysts, chemical fibers, electronics, cosmetics, etc. Therefore, the research on preparation technology and industrial production has become more important.

[0003] At present, the methods for preparing nano zinc oxide include precipitation method, low-temperature hydrothermal method, sol-gel method, spray pyrolysis method and gas-phase synthesis method. The homogeneous precipitation method is adopted by most zinc oxide production enterprises due to its low preparation cost and simple process control. However, the nano zinc oxide prepared by it has a wide particle size distribution, poor monodispersity and irregular morphology, which greatly limits the use performance and application fields of nano zinc oxide. At present, all methods have problems such as long reaction time, large particle size and uneven particle size distribution.

[0004] Our company applied for a Chinese invention patent (CN117023625A) for a product of flaky porous nano zinc oxide material, a flaky porous nano zinc oxide and its preparation method and application. In the present invention, a basic zinc carbonate precursor is first prepared, and then nitrogen is introduced to make the pressure of the system > 0.4 MPa and < 0.6 MPa for hydrothermal reaction, and then the reaction product is calcined to obtain flaky porous nano zinc oxide. The morphology of the flaky porous nano zinc oxide prepared by the method of the present invention is a uniform and regular flaky porous structure. The pores on the flakes are uniform, regular and dense, with small particle size and large specific surface area, and can be widely applied to fields such as the degradation of organic pollutants in the photocatalytic system and heavy metal adsorption. The preparation method of the present invention uses easily available raw materials and can be mass-produced.

[0005] On this basis, our team further explores nano zinc oxide materials and preparation methods. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation method of spherical nano zinc oxide with a large specific surface area, which includes the following steps: (1) Pretreat the zinc-containing mineral to obtain a zinc sulfate solution, and respectively prepare a sodium carbonate solution and a composite surfactant; (2) Add the three groups of solutions in parallel into the multiphase interface reactor, and carry out a precipitation reaction at room temperature to obtain a basic zinc carbonate precursor slurry; (3) Microwave heat the obtained basic zinc carbonate precursor slurry; (4) Age, wash, and dry the basic zinc carbonate precursor slurry obtained in step (3) to obtain a basic zinc carbonate precursor solid; (5) Calcinate the obtained basic zinc carbonate precursor solid and crush it to obtain zinc oxide powder.

[0007] Preferably, in step (2), the inlet gas pressure is 0.04 MPa - 0.06 MPa.

[0008] Preferably, in step (3), the power of microwave heating is 500 W - 900 W, and the microwave time is 1 min - 3 min.

[0009] Preferably, in step (1), the composite surfactant includes sodium oleate, polyvinylpyrrolidone, and polyethylene glycol 6000.

[0010] Preferably, in step (2), the parallel flow rate of the three groups of solutions is 150 mL / min - 300 mL / min, and the stirring speed of the multiphase interface reactor is 1200 r / min - 3500 r / min.

[0011] Preferably, in step (1), the pretreatment is acid leaching and replacement purification of zinc-containing minerals. The concentration of sulfuric acid leaching is 15%, the time is 1 h. After sedimentation and filtration, the temperature of the leaching solution is raised to 70 °C, and zinc powder is added for replacement of heavy metal ions such as copper, lead, and cadmium. The replacement reaction is carried out at 70 °C for 1 h. After filtering the obtained zinc sulfate solution, it is then formulated into a zinc sulfate solution with a concentration of 0.4 mol / L - 0.85 mol / L, and the concentration of the sodium carbonate solution is 0.5 mol / L - 2.0 mol / L.

[0012] Preferably, the concentration of the zinc sulfate solution is 0.55 mol / L, and the concentration of the sodium carbonate solution is 1.5 mol / L.

[0013] Preferably, in step (4), the aging temperature is 25 °C, and the aging time is 1 h.

[0014] Preferably, in step (4), during the washing process, the solid-liquid ratio is 1:6, and pure water is used for washing 6 times at 50 °C - 60 °C.

[0015] Preferably, in step (4), the drying method is spray drying, the inlet air temperature is 220 °C, and the outlet air temperature is 60 °C.

[0016] Preferably, in step (5), the calcination temperature is 400°C - 700°C, and the calcination time is 30 min - 120 min.

[0017] Preferably, in step (5), the pulverization device is a pneumatic ultrafine mill.

[0018] Another object of the present invention is to provide a spherical nano-zinc oxide with a large specific surface area, which is prepared by the above preparation method. The particle size of the nano-zinc oxide is 16 nm - 39 nm, and the specific surface area is: 70 - 80 m 2 / g.

[0019] The present invention has the following beneficial effects.

[0020] 1. Compared with the patent (CN117023625A) in the background art, the nano-zinc oxide prepared by the present invention has a spherical morphology, a higher specific surface area, better dispersibility, smaller particle size, and a narrower particle size distribution. Compared with the original preparation method, the present invention abandons the hydrothermal method with long time and slow reaction, and selects the co-precipitation method with constant temperature and pressure and short time. By introducing gas, more gas is applied in the reaction system, and the obtained nano-zinc oxide has better dispersibility, higher specific surface area, and higher purity. At the same time, microwave reaction is added. Microwave reaction can heat quickly and uniformly, significantly accelerating the reaction rate and improving the product characteristics. The obtained nano-zinc oxide has a narrower particle size distribution, higher yield, and a high specific surface area.

[0021] 2. The present invention uses purified zinc-containing waste residue as raw material, which not only improves the utilization rate of raw materials, but also improves the purity of the product. The process of the present invention is relatively simple and easy to implement, with low cost, high conversion rate, low energy consumption, and easy to master reaction conditions. The nano-zinc oxide prepared by the present invention has a spherical morphology, a higher specific surface area, better dispersibility, smaller particle size, and a narrower particle size distribution. By introducing gas in the synthesis process, more gas is applied in the reaction system, the bubbles generated by stirring are denser, and the reaction environment is narrower. Therefore, the obtained nano-zinc oxide has better dispersibility, higher specific surface area, and higher purity. At the same time, microwave reaction is added. Microwave reaction can heat quickly and uniformly. By directly acting on the reaction system through microwave radiation, the reaction rate is significantly accelerated and the product characteristics are improved. Microwave energy directly acts on the reactants, avoiding heat loss in traditional heating. The particle size distribution of microwave synthesis is narrower than that of traditional methods, and the size can be controlled during synthesis, with a higher yield. The yield of preparing zinc oxide by the ordinary direct precipitation method is 70% - 90%, and the present invention can increase the yield to 99%. Description of the Drawings

[0022] Figure 1 XRD pattern (X-ray diffraction pattern) of the nano-zinc oxide prepared in Example 1.

[0023] Figure 2SEM image (scanning electron microscope image) of the nano-zinc oxide prepared in Example 1.

[0024] Figure 3 Particle size distribution diagram of the nano-zinc oxide prepared in Example 1.

[0025] Figure 4 SEM image (scanning electron microscope image) of the nano-zinc oxide prepared in Example 2.

[0026] Figure 5 Particle size distribution diagram of the nano-zinc oxide prepared in Example 2.

[0027] Figure 6 SEM image (scanning electron microscope image) of the nano-zinc oxide prepared in Example 3.

[0028] Figure 7 Particle size distribution diagram of the nano-zinc oxide prepared in Example 3. Detailed implementation mode

[0029] Example 1: (1) Acid-leach and replace and purify the zinc-containing mineral, and filter to obtain a purified zinc sulfate solution; (2) Configure the purified zinc sulfate solution obtained in step (1) into a zinc sulfate solution with a concentration of 0.55 mol / L, configure the sodium carbonate raw material into a sodium carbonate solution with a concentration of 1.5 mol / L, and configure the surfactant into 2% sodium oleate, 0.05% polyvinylpyrrolidone and 0.005% polyethylene glycol 6000; (3) Add the three-component solution obtained in step (2) to a multiphase interface reactor for co-current precipitation reaction. The stirring speed of the co-current precipitation reaction is 3000 r / min, the flow rate is 300 ml / min, the inlet gas pressure is 0.06 MPa, and the temperature is room temperature to obtain a basic zinc carbonate precursor slurry; (4) Microwave heat the basic zinc carbonate precursor slurry obtained in step (3) with a power of 700 W and a microwave time of 2 min to obtain a basic zinc carbonate precursor slurry; (5) Age the basic zinc carbonate precursor slurry obtained in step (4) at an aging temperature of 60 °C and an aging time of 2 h to obtain an aged slurry of basic zinc carbonate precursor; (6) Wash the aged slurry of basic zinc carbonate precursor obtained in step (5). In the washing step, the solid-liquid ratio is 1:6, and it is washed 6 times with pure water at 50 °C. The drying method is spray drying, the inlet air temperature is 220 °C, and the outlet air temperature is 60 °C to obtain a solid of basic zinc carbonate precursor; (7) Calcinate the basic zinc carbonate precursor solid obtained in step (6) at a calcination temperature of 550 °C for a calcination time of 50 min. The comminution equipment used is a pneumatic ultrafine mill, and after comminution, nano-zinc oxide powder with a particle size of 16 nm - 39 nm and a specific surface area of 80 m 2 / g is obtained. The nano-zinc oxide powder is spherical and has a high specific surface area. As Figure 1 shown in the XRD pattern (X-ray diffraction pattern) of nano-zinc oxide. By comparing and analyzing the pattern, the diffraction peak positions and interplanar spacings (d) of the sample are in line with the standard diffraction pattern of zinc oxide, and there are no other impurity peaks, which proves that the prepared zinc oxide is a pure phase. As Figure 2 shown in the SEM image (scanning electron microscope image) of nano-zinc oxide. As Figure 3 shown in the particle size distribution diagram of nano-zinc oxide. As Figure 4 shown in the specific surface area data of nano-zinc oxide.

[0030] Example 2: (1) Acid-leach and purify the zinc-containing mineral, and filter to obtain a purified zinc sulfate solution; (2) Configure the purified zinc sulfate solution obtained in step (1) into a zinc sulfate solution with a concentration of 0.85 mol / L, configure the sodium carbonate raw material into a sodium carbonate solution with a concentration of 2.0 mol / L, and configure the surfactant into 2% sodium oleate, 0.05% polyvinylpyrrolidone, and 0.005% polyethylene glycol 6000; (3) Add the three-component solution obtained in step (2) to a multiphase interface reactor for co-current precipitation reaction. The stirring speed of the co-current precipitation reaction is 3500 r / min, the flow rate is 300 ml / min, the inlet gas pressure is 0.04 MPa, and the temperature is room temperature to obtain a basic zinc carbonate precursor slurry; (4) Microwave-heat the basic zinc carbonate precursor slurry obtained in step (3) at a power of 500 W for a microwave time of 3 min to obtain a basic zinc carbonate precursor slurry; (5) Age the basic zinc carbonate precursor slurry obtained in step (4) at an aging temperature of 80 °C for an aging time of 4 h to obtain an aged slurry of basic zinc carbonate precursor; (6) Wash the aged slurry of basic zinc carbonate precursor obtained in step (5). In the washing step, the solid-liquid ratio is 1:6, and it is washed 6 times with pure water at 50 °C. The drying method is spray drying, the inlet air temperature is 250 °C, and the outlet air temperature is 80 °C to obtain a basic zinc carbonate precursor solid; (7) Calcinate the basic zinc carbonate precursor solid obtained in step (6) at a calcination temperature of 400 °C for a calcination time of 120 min. The comminution equipment used is a pneumatic ultrafine mill, and after comminution, nano-zinc oxide powder with a particle size of 16 nm - 39 nm and a specific surface area of 73 m 2 / g nano-zinc oxide powder, the nano-zinc oxide powder is spherical and has a high specific surface area. As Figure 4 SEM image of nano-zinc oxide (scanning electron microscopy image), as Figure 5 Particle size distribution diagram of nano-zinc oxide.

[0031] Example 3: (1) Acid-leach and replace to purify the zinc-containing mineral, and filter to obtain a purified zinc sulfate solution; (2) Configure the purified zinc sulfate solution obtained in step (1) into a zinc sulfate solution with a concentration of 0.4 mol / L, configure the sodium carbonate raw material into a sodium carbonate solution with a concentration of 0.5 mol / L, and configure the surfactant into 2% sodium oleate, 0.05% polyvinylpyrrolidone and 0.005% polyethylene glycol 6000; (3) Add the three-component solution obtained in step (2) to a multiphase interface reactor for co-current precipitation reaction. The stirring speed of the co-current precipitation reaction is 1200 r / min, the flow rate is 150 mL / min, the inlet gas pressure is 0.05 MPa, and the temperature is room temperature to obtain a basic zinc carbonate precursor slurry; (4) Microwave-heat the basic zinc carbonate precursor slurry obtained in step (3) with a power of 900 W and a microwave time of 1 min to obtain a basic zinc carbonate precursor slurry; (5) Age the basic zinc carbonate precursor slurry obtained in step (4) at an aging temperature of 25 °C and an aging time of 1 h to obtain an aged slurry of basic zinc carbonate precursor; (6) Wash the aged slurry of basic zinc carbonate precursor obtained in step (5). In the washing step, the solid-liquid ratio is 1:6, and it is washed 6 times with pure water at 60 °C. The drying method is spray drying, the inlet air temperature is 220 °C, and the outlet air temperature is 60 °C to obtain a solid of basic zinc carbonate precursor; (7) Calcinate the solid of basic zinc carbonate precursor obtained in step (6) at a calcination temperature of 600 °C and a calcination time of 30 min. The pulverizing equipment used is a pneumatic ultrafine pulverizer, and the pulverized product has a particle size of 16 nm - 39 nm and a specific surface area of 70 m 2 / g nano-zinc oxide powder, the nano-zinc oxide powder is spherical and has a high specific surface area. As Figure 6 SEM image of nano-zinc oxide (scanning electron microscopy image), as Figure 7 Particle size distribution diagram of nano-zinc oxide.

[0032] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that: (1) There is no step of introducing gas; (2) The microwave heating power is 700 W and the heating time is 2 min.

[0033] The particle size of the nano-zinc oxide prepared in Comparative Example 1 was 34.81 nm, and the specific surface area was 42 m 2 / g.

[0034] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that: (1) The intake pressure was 0.06 MPa; (2) There was no microwave reaction step.

[0035] The particle size of the nano-zinc oxide prepared in Comparative Example 2 was 39.00 nm, and the specific surface area was 66 m 2 / g.

[0036] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of spherical nano-zinc oxide with a large specific surface area, characterized in that, It includes the following steps: (1) Pretreat the zinc-containing mineral to obtain a zinc sulfate solution, and prepare a sodium carbonate solution and a composite surfactant respectively; (2) Add the three groups of solutions in parallel into a multiphase interface reactor, carry out a precipitation reaction at room temperature, and introduce air to obtain a basic zinc carbonate precursor slurry; (3) Microwave heat the prepared basic zinc carbonate precursor slurry; (4) Age, wash, and dry the basic zinc carbonate precursor slurry prepared in step (3) to obtain a solid basic zinc carbonate precursor; (5) Calcinate the obtained solid basic zinc carbonate precursor and crush it to obtain zinc oxide powder.

2. The preparation method according to claim 1, wherein, In step (2), the inlet air pressure is 0.04 MPa - 0.06 MPa.

3. The preparation method according to claim 1, wherein In step (3), the power of microwave heating is 500 W - 900 W, and the microwave time is 1 min - 3 min.

4. The preparation method according to claim 1, characterized in that, In step (1), the composite surfactant includes sodium oleate, polyvinylpyrrolidone, and polyethylene glycol 6000.

5. The preparation method according to claim 1, characterized in that, In step (2), the parallel flow rate of the three groups of solutions is 150 mL / min - 300 mL / min, and the stirring speed of the multiphase interface reactor is 1200 r / min - 3500 r / min.

6. The preparation method according to claim 1, wherein In step (1), the pretreatment is to carry out acid leaching and displacement purification on the zinc-containing mineral. The sulfuric acid leaching concentration is 15%, the time is 1 h. After sedimentation and filtration, the temperature of the leaching solution is raised to 70 °C, zinc powder is added to displace heavy metal ions, and the displacement reaction is carried out at 70 °C for 1 h. After filtering the prepared zinc sulfate solution, it is then formulated into a zinc sulfate solution with a concentration of 0.4 mol / L - 0.85 mol / L, and the concentration of the sodium carbonate solution is 0.5 mol / L - 2.0 mol / L.

7. The preparation method according to claim 1, characterized in that, In step (4), the aging temperature is 25 °C, and the aging time is 1 h; During the washing process, the solid-liquid ratio is 1:6, and pure water at 50 °C - 60 °C is used for washing 6 times; The drying method is spray drying, the inlet air temperature is 220 °C, and the outlet air temperature is 60 °C.

8. The preparation method according to claim 1, wherein In step (5), the calcination temperature is 400 °C - 700 °C, and the calcination time is 30 min - 120 min.

9. A spherical nano-zinc oxide with a large specific surface area, which is prepared by the preparation method described in any one of claims 1-9, is characterized in that, The particle size of the nano-zinc oxide is 16 nm - 39 nm, and the specific surface area is 70 - 80 m 2 / g.

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