CN113732279B - Preparation method of nano gold particles serving as electron microscope developer and obtained nano gold particles - Google Patents
Preparation method of nano gold particles serving as electron microscope developer and obtained nano gold particles Download PDFInfo
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- 239000002245 particle Substances 0.000 title claims abstract description 121
- 239000010931 gold Substances 0.000 title claims abstract description 110
- 229910052737 gold Inorganic materials 0.000 title claims abstract description 110
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 title claims abstract description 81
- 238000002360 preparation method Methods 0.000 title claims abstract description 34
- 239000012279 sodium borohydride Substances 0.000 claims abstract description 41
- 229910000033 sodium borohydride Inorganic materials 0.000 claims abstract description 41
- 239000002253 acid Substances 0.000 claims abstract description 40
- 239000002243 precursor Substances 0.000 claims abstract description 30
- 239000002105 nanoparticle Substances 0.000 claims abstract description 27
- LZZYPRNAOMGNLH-UHFFFAOYSA-M Cetrimonium bromide Chemical compound [Br-].CCCCCCCCCCCCCCCC[N+](C)(C)C LZZYPRNAOMGNLH-UHFFFAOYSA-M 0.000 claims abstract description 26
- 239000003381 stabilizer Substances 0.000 claims abstract description 17
- 238000006479 redox reaction Methods 0.000 claims abstract description 14
- 239000000463 material Substances 0.000 claims abstract description 4
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 30
- 230000005484 gravity Effects 0.000 claims description 11
- 239000006185 dispersion Substances 0.000 claims description 10
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- 230000001105 regulatory effect Effects 0.000 abstract description 7
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- 230000000052 comparative effect Effects 0.000 description 10
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- 238000006243 chemical reaction Methods 0.000 description 9
- 238000000034 method Methods 0.000 description 7
- 239000001509 sodium citrate Substances 0.000 description 6
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 description 6
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- 239000000203 mixture Substances 0.000 description 3
- 239000002872 contrast media Substances 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000001493 electron microscopy Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
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- 238000004220 aggregation Methods 0.000 description 1
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- 238000010894 electron beam technology Methods 0.000 description 1
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- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y15/00—Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N11/00—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
Abstract
The invention discloses a preparation method of nano gold particles serving as an electron microscope developer and the obtained nano gold particles. The invention firstly discloses a preparation method of nano gold particles serving as an electron microscope developer, which uses chloroauric acid as a precursor material, cetyltrimethylammonium bromide as a stabilizer, sodium borohydride as a reducing agent, and performs oxidation-reduction reaction in a supergravity rotating packed bed to obtain the nano gold particles. The invention further provides the nano gold particles prepared by the preparation method. According to the preparation method of gold nanoparticles, the feeding flow rate and the rotor rotating speed of the supergravity rotating packed bed are regulated to obtain better technological parameters, so that the continuous production is convenient and safe, the obtained gold nanoparticles are uniform in appearance and size, the particle size is 1-3nm, and the gold nanoparticles are smaller than the general gold seed size; and the particles have good dispersibility and long storage time.
Description
Technical Field
The invention relates to the technical field of nano material preparation. More particularly, to a method for preparing nano gold particles as an electron microscope developer and the obtained nano gold particles.
Background
Since the first Transmission Electron Microscope (TEM) was developed by e.ruska and m.knoll in 1932, humans began to enter the nanoworld, and the widespread use of electron microscopy and the rapid development of electron microscopy have greatly promoted the development of materials science, physics, and life sciences. The electron beam transmitted through the sample carries information on intensity, phase and periodicity, and the information generated by the interaction of these electrons with the substance is contained in the TEM image, allowing one to recognize the microscopic world on an atomic scale. In order to reveal the evolution rule and quantitative analysis of nano-scale multiphase transfer behaviors, monodisperse nano-gold particles are needed to be used as contrast agents when an electron microscope is adopted to in-situ observe nano-micro-scale flow behaviors, so that tracing of different fluids is realized. The nano gold particles used as contrast agents need to have high imaging contrast, namely, large atomic number difference and high shape distinction; has high dispersion stability, low specific surface energy and low steric hindrance.
Gold element with atomic number 79 has stable chemical properties, and has plasmon resonance effect controlled by particle size and morphology when its scale is in nanometer scale, which has attracted attention. The nano gold particles are easy to change the surface property by modification, so that the interaction between the particles and the liquid medium and the interaction between the particles are changed, and a better dispersing effect is achieved. The TEM image of the nano gold particles has enough contrast, so that the nano gold particles have good application prospect when used as an electron microscope developer for in-situ observation of nano-micro scale flow behavior. At present, a seed-induced two-step method is generally used for synthesizing gold nanoparticles with different morphologies, wherein the synthesized gold seeds are nearly spherical, and the particle size is about 3.5 nm. At present, the preparation of small-size gold balls has the following problems: the particle size of the nano gold particles is not uniform enough; the large-scale preparation cannot be realized, and the product difference of different batches is larger.
Therefore, a new method for preparing nano-gold particles that can be used as an electron microscope developer is needed to solve the above-mentioned problems.
Disclosure of Invention
An object of the present invention is to provide a method for preparing nano gold particles as a developer for an electron microscope, which is convenient and safe and can realize continuous production by using a super-gravity rotating packed bed as a reactor.
The invention also aims to provide the nano gold particles prepared by the preparation method, wherein the average particle size of the nano gold particles is about 2nm (1-3 nm), the particle size is uniform, the nano gold particles are well dispersed in an aqueous solution, and the storage time is long.
In order to achieve the above purpose, the present invention firstly provides a preparation method of nano gold particles as an electron microscope developer, wherein chloroauric acid is used as a precursor material, cetyltrimethylammonium bromide is used as a stabilizer, sodium borohydride is used as a reducing agent, and oxidation-reduction reaction is performed in a super-gravity rotating packed bed to obtain the nano gold particles.
Based on the preparation method of the present invention, preferably, the preparation method of the nano gold particles as the electron microscope developer comprises the following steps:
dissolving chloroauric acid in water to obtain chloroauric acid solution;
dissolving cetyl trimethyl ammonium bromide in water to obtain a stabilizer solution, dropwise adding a chloroauric acid solution into the stabilizer solution, and fully stirring and mixing to obtain a precursor solution;
dissolving sodium borohydride in water to obtain sodium borohydride solution;
and (3) conveying the precursor solution and the sodium borohydride solution into a hypergravity rotating packed bed, performing redox reaction, centrifuging and washing to obtain the gold nanoparticle dispersion liquid.
The nano gold particles of the invention are difficult to preserve because of the low mass fraction and the small amount after drying, and therefore are generally dispersed in water to preserve in the form of dispersion liquid.
The present invention relates to a supergravity technology, which is a technology for providing a centrifugal force field by a supergravity rotary packed bed and utilizing the unique flow phenomenon of multiphase fluid under the supergravity environment to strengthen mass transfer and micromixing between the fluids. In the super-gravity environment, the mass transfer and diffusion rates of molecules are usually 1 to 3 orders of magnitude higher than those of conventional stirring, so that the micromixing process can be greatly enhanced. For the gold nanoparticle, the centrifugal force and the shearing force provided by the hypergravity technology are utilized to strengthen the reaction mass transfer, so that particles with small size and uniform particle size distribution can be synthesized, the particle size is about 2nm under the condition of better process parameters, the dispersion and the stability are good, the gold nanoparticle can be used as an electron microscope developer, and the gold nanoparticle is suitable for in-situ observation and research of the nano-micro scale flow behavior rule. In addition, as a continuous reactor, the supergravity rotary packed bed can realize continuous production of products, and is safe and convenient.
Based on the preparation method, cetyl trimethyl ammonium bromide is selected as a stabilizer, is a cationic surfactant and is adsorbed on the liquid-solid interface of the nano particles, so that the attribute of the particle surface is changed, the interface free energy is reduced, and a solvated film is formed, so that the particle dispersion stability is ensured; and other stabilizers are selected to have higher preparation difficulty, which is easy to cause aggregation of gold particles, so that the storage time of the gold particles is shortened.
Based on the preparation method of the invention, the molar ratio of hexadecyl trimethyl ammonium bromide to chloroauric acid in the precursor solution is 50:1-200:1; preferably, the molar ratio of the cetyl trimethyl ammonium bromide to the chloroauric acid is 100:1-150:1. In the invention, the dosage of hexadecyl trimethyl ammonium bromide and chloroauric acid is outside the range, and less hexadecyl trimethyl ammonium bromide and chloroauric acid can not be adsorbed on the surfaces of the nano particles to wrap the particles, so that the effect of dispersing the nano particles can not be achieved; the foaming is serious in the reaction process, supersaturation adsorption occurs, and redundant chain molecules in the liquid phase can be mutually connected to cause flocculation and are difficult to clean.
Based on the preparation method, when the precursor solution and the sodium borohydride solution are conveyed into a super-gravity rotary packed bed, the molar ratio of the sodium borohydride in the sodium borohydride solution to chloroauric acid in the precursor solution is 2:1-10:1; preferably, the molar ratio of the sodium borohydride to the chloroauric acid is 4:1-6:1. In the invention, the dosage of sodium borohydride and chloroauric acid is outside the range, and less sodium borohydride reacts with water to release hydrogen, so that a certain amount of loss is caused and the sodium borohydride is insufficient for completely reducing chloroauric acid; many times, the waste is caused by insufficient utilization.
Based on the preparation method, the oxidation-reduction reaction is carried out at normal temperature and normal pressure, namely the temperature of the oxidation-reduction reaction is 5-25 ℃; preferably, the temperature of the redox reaction is 15-25 ℃. The oxidation-reduction reaction can be carried out at normal temperature without consuming extra energy.
Based on the preparation method of the invention, the feeding flow rate of the super gravity rotary packed bed is 11.8-30.0L/h. In the invention, when the feeding flow rate is out of the range, two reaction solutions cannot be fully contacted with each other, the liquid holdup in the supergravity rotary packed bed is too small, and the particle size of the nano gold particles synthesized by reaction is larger and nonuniform; the energy consumption is larger if the temperature is high, and the product quality is not obviously improved.
Based on the preparation method of the invention, the feed interface of the super-gravity rotary packed bed adopts premixing. In the invention, if a non-premixed interface is adopted, two liquids cannot be fully contacted, and the particle size distribution of the nano gold particles synthesized by the reaction is wider.
Based on the preparation method of the invention, the rotating speed of the rotor of the super-gravity rotary packed bed is 600-2400rpm; preferably, the rotor speed is 1000-2000rpm; more preferably, the rotor speed is 1000rpm. In the invention, a frequency modulation speed changer is adopted to adjust the rotating speed of the rotor, the rotating speed of the rotor is out of the range, the mixing effect is general when the rotating speed is low, and the formed particles are larger and nonuniform in size; high energy consumption and serious machine loss, and the product quality is not obviously improved.
Based on the preparation method of the present invention, preferably, sodium borohydride is dissolved in water at 0 ℃ at the time of preparing the sodium borohydride solution.
Based on the preparation method of the invention, preferably, the water used in the preparation method is deionized water.
The invention further provides the nano gold particles prepared by the preparation method.
According to the present invention, the gold nanoparticles have a particle diameter of 1 to 10nm, preferably 1 to 3nm. The nano gold particles can be dispersed in water and have good dispersibility.
Any range recited in the present invention includes any numerical value between the end values and any sub-range formed by any numerical value between the end values or any numerical value between the end values unless specifically stated otherwise.
The beneficial effects of the invention are as follows:
1) According to the preparation method of gold nanoparticles, the feeding flow rate and the rotor rotating speed of the supergravity rotating packed bed are adjusted to obtain the optimal technological parameters, so that the method is convenient and safe, and continuous production can be realized.
2) The gold nanoparticles prepared by the optimized process of the preparation method have uniform morphology and uniform size, the particle size is 1-3nm, and the size is smaller than that of the general gold seeds (the particle size is about 3.5 nm); and the particles have good dispersibility and long storage time.
Drawings
The following describes the embodiments of the present invention in further detail with reference to the drawings.
FIG. 1 is a transmission electron microscope image of the nano-gold particles prepared in example 1 with a feeding flow rate of 11.8L/h of the super gravity rotary packed bed.
FIG. 2 is a transmission electron microscope image of the nano-gold particles prepared in example 1 with a feeding flow rate of 17.8L/h of the super gravity rotating packed bed.
FIG. 3 is a transmission electron microscope image of the nano-gold particles prepared in example 1 with a feeding flow rate of 25.4L/h of the super gravity rotating packed bed.
FIG. 4 is a transmission electron microscope image of the nano-gold particles prepared in example 1 with a feed flow rate of 30.0L/h for the super gravity rotating packed bed.
FIG. 5 is a transmission electron microscope image of the nano-gold particles prepared in example 2 in which the rotor speed of the super-gravity rotating packed bed was 600 rpm.
FIG. 6 is a transmission electron microscope image of the nano-gold particles prepared in example 2 in which the rotor speed of the super-gravity rotating packed bed was 1000rpm.
FIG. 7 is a transmission electron microscope image of the nano-gold particles prepared in example 2 in which the rotor speed of the super-gravity rotating packed bed was 1500 rpm.
FIG. 8 is a transmission electron microscope image of the nano-gold particles prepared in example 2 in which the rotor speed of the super-gravity rotating packed bed was 2000 rpm.
FIG. 9 is a transmission electron microscope image of the nano-gold particles prepared in example 2 in which the rotation speed of the rotor of the super-gravity rotating packed bed was 2400 rpm.
FIG. 10 is a transmission electron microscope image of the nano-gold particles prepared in example 3.
FIG. 11 is a transmission electron microscope image of the nano-gold particles prepared in comparative example 1 with a feed flow rate of 11.8L/h for the super gravity rotating packed bed.
FIG. 12 is a transmission electron microscopic image of the nano-gold particles produced in comparative example 1 with a feed flow rate of 17.8L/h of the super gravity rotating packed bed.
FIG. 13 is a transmission electron microscope image of the nano-gold particles produced in comparative example 1 at a feed flow rate of 25.4L/h for the super gravity rotating packed bed.
FIG. 14 is a transmission electron microscopic image of the nano-gold particles produced in comparative example 1 at a feed flow rate of 30.0L/h for the super gravity rotating packed bed.
FIG. 15 is a transmission electron microscopic image of the nano-gold particles prepared in comparative example 2.
FIG. 16 is a transmission electron microscopic image of the nano-gold particles prepared in comparative example 4.
Detailed Description
In order to more clearly illustrate the present invention, the present invention will be further described with reference to preferred embodiments and the accompanying drawings. Like parts in the drawings are denoted by the same reference numerals. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and that this invention is not limited to the details given herein.
Example 1
The preparation method of the nano gold particles used as the electron microscope developer specifically comprises the following steps:
1g of chloroauric acid is dissolved in deionized water to prepare 25mM chloroauric acid solution, and the solution is stored at 4 ℃ in a dark place; 1.822g (5 mmol) of cetyltrimethylammonium bromide is taken and dissolved in 98mL of deionized water to obtain cetyltrimethylammonium bromide solution (namely stabilizer solution), 2mL of 25mM chloroauric acid solution is taken and added into cetyltrimethylammonium bromide solution, and the mixture is fully stirred and mixed to obtain precursor solution, wherein the molar ratio of cetyltrimethylammonium bromide to chloroauric acid in the precursor solution is 100:1;
dissolving 37.83mg of sodium borohydride in 10mL of deionized water at 0 ℃, and adding 2mL of the solution into 98mL of deionized water by using a pipette to obtain sodium borohydride solution;
dividing a precursor solution and a sodium borohydride solution (the molar ratio of chloroauric acid in the precursor solution to sodium borohydride in the sodium borohydride solution is 1:4) into four groups, starting a hypergravity rotary packed bed, and regulating the rotating speed to 1800rpm; starting a feed pump, regulating the feed flow rates to be 11.8L/h, 17.8L/h, 25.4L/h and 30L/h respectively, simultaneously conveying each group of precursor solution and sodium borohydride solution into a supergravity rotating packed bed from a premixing interface, carrying out oxidation-reduction reaction at normal temperature and normal pressure, instantly completing the reaction, discharging, repeatedly centrifuging, washing with deionized water, and removing excessive cetyltrimethylammonium bromide to obtain gold nanoparticle dispersion liquid prepared by the feed flow rates of 11.8L/h, 17.8L/h, 25.4L/h and 30L/h respectively.
FIG. 1 is a transmission electron microscope image of the nano-gold particles produced at a feed flow rate of 11.8L/h; FIG. 2 is a transmission electron microscope image of the nano-gold particles produced at a feed flow rate of 17.8L/h; FIG. 3 is a transmission electron microscope image of the nano-gold particles prepared with a feed pump feed flow rate of 25.4L/h; FIG. 4 is a transmission electron microscope image of the nano gold particles prepared at a feed flow rate of 30L/h, and it can be seen that the prepared nano gold particles are below 5nm under different feed flow rates, and the particle size distribution is narrower.
Example 2
The preparation method of the nano gold particles used as the electron microscope developer specifically comprises the following steps:
1g of chloroauric acid is dissolved in deionized water to prepare 25mM chloroauric acid solution, and the solution is stored at 4 ℃ in a dark place; 1.822g of cetyltrimethylammonium bromide is dissolved in 98mL of deionized water to obtain cetyltrimethylammonium bromide solution (namely stabilizer solution), 2mL of 25mM chloroauric acid solution is taken into the cetyltrimethylammonium bromide solution, and the mixture is fully stirred and mixed to obtain precursor solution, wherein the molar ratio of the cetyltrimethylammonium bromide to the chloroauric acid in the precursor solution is 100:1;
dissolving 37.83mg of sodium borohydride in 10mL of deionized water at 0 ℃, and adding 2mL of the solution into 98mL of deionized water by using a pipette to obtain sodium borohydride solution;
dividing a precursor solution and a sodium borohydride solution (the molar ratio of chloroauric acid in the precursor solution to sodium borohydride in the sodium borohydride solution is 1:4) into five groups, starting a super-gravity rotating packed bed, and adjusting the rotating speed of a rotor to be 600rpm, 1000rpm, 1500rpm, 2000rpm and 2400rpm respectively; starting a feed pump, regulating the feed flow rate to be 25.4L/h, simultaneously conveying the precursor solution and the sodium borohydride solution into a supergravity rotating packed bed from a premixing interface by each group, carrying out oxidation-reduction reaction at normal temperature and normal pressure, instantly completing the reaction, discharging, repeatedly centrifuging and washing with deionized water to remove the excessive cetyltrimethylammonium bromide, and obtaining the gold nanoparticle dispersion liquid prepared by rotor rotating speeds of 600rpm, 1000rpm, 1500rpm, 2000rpm and 2400rpm respectively.
FIG. 5 is a transmission electron microscope image of the gold nanoparticles produced at a rotor speed of 600rpm, under which conditions the gold nanoparticles had a larger particle size, a portion of the size was 10nm, and the particle size distribution was non-uniform. FIG. 6 is a transmission electron microscope image of the nano gold particles prepared by the rotor rotating speed of 1000rpm, under the condition that the nano gold particles have uniform particle size distribution and good monodispersity, and the particle size is 1-3nm. FIG. 7 is a transmission electron microscope image of the nano gold particles prepared at a rotor rotation speed of 1500rpm, under the condition that the particle size distribution of the nano gold particles is uniform, the nano gold particles are in a spherical shape, and the particle size is 4-5 nm. FIG. 8 is a transmission electron microscope image of gold nanoparticles produced at a rotor speed of 2000rpm, under which gold nanoparticles have a non-uniform particle size, small-sized (< 5 nm) gold particles are attached to a stabilizer, and the dispersibility is poor. FIG. 9 is a transmission electron microscope image of gold nanoparticles produced at a rotor speed of 2400rpm, under which gold nanoparticles have a wide particle size distribution, and a small portion of gold nanoparticles having a small particle size are aggregated around a stabilizer or gold nanoparticles having a large particle size. In summary, it can be seen from a transmission electron micrograph of the resulting product from 5 sets of different rotor speeds that a rotor speed of 1000rpm is the preferred choice.
Example 3
The preparation method of the nano gold particles used as the electron microscope developer specifically comprises the following steps:
1g of chloroauric acid is dissolved in deionized water to prepare 25mM chloroauric acid solution, and the solution is stored at 4 ℃ in a dark place; 1g of cetyltrimethylammonium bromide (2.7 mmol) is taken and dissolved in 98mL of deionized water to obtain cetyltrimethylammonium bromide solution (namely stabilizer solution), 2mL of 25mM chloroauric acid solution is taken and added into cetyltrimethylammonium bromide solution, and the mixture is fully stirred and mixed to obtain precursor solution, wherein the mole ratio of cetyltrimethylammonium bromide to chloroauric acid in the precursor solution is 54:1;
dissolving 37.83mg of sodium borohydride in 10mL of deionized water at 0 ℃, and adding 2mL of the solution into 98mL of deionized water by using a pipette to obtain sodium borohydride solution;
starting the super-gravity rotating device, and adjusting the rotating speed of the rotor to 1000rpm; starting a feed pump, regulating the feed flow rate to be 25.4L/h, simultaneously conveying a precursor solution and a sodium borohydride solution (the molar ratio of chloroauric acid in the precursor solution to sodium borohydride in the sodium borohydride solution is 1:4) from a premixing interface into a rotary packed bed, performing oxidation-reduction reaction at normal temperature and normal pressure, instantly completing the reaction, discharging, repeatedly centrifuging, washing with deionized water, and removing redundant cetyltrimethylammonium bromide solution to obtain the gold nanoparticle dispersion.
Fig. 10 is a transmission electron microscope image of the obtained nano gold particles, and it can be seen from the image that the nano gold particles have smaller particle size and narrower size distribution, but are easy to be attached to the stabilizer and have general dispersibility.
Comparative example 1
Example 1 was repeated, with the only difference that: super gravity rotating packed bed non-premixed interface feeds were used.
FIG. 11 is a transmission electron microscope image of the nano-gold particles produced at a feed flow rate of 11.8L/h; FIG. 12 is a transmission electron microscope image of the nano-gold particles produced at a feed flow rate of 17.8L/h; FIG. 13 is a transmission electron microscope image of the nano-gold particles produced at a feed flow rate of 25.4L/h; FIG. 14 is a transmission electron microscope image of the nano-gold particles prepared at a feed flow rate of 30L/h. It can be seen that the obtained nano gold particles have larger particle size, generally more than 10nm and wider particle size distribution under the condition of no premixing feeding.
Comparative example 2
Example 1 was repeated, with the only difference that: the redox reaction is carried out in a traditional stirred tank without using a supergravity rotary packed bed, the molar ratio of chloroauric acid in the precursor solution to sodium borohydride in the sodium borohydride solution is 1:5, and the reaction time is 5min.
FIG. 15 is a transmission electron microscope image of the produced nano gold particles, from which it can be seen that the particle size is 1-5nm, and the nano gold particles of a larger size account for a larger amount.
Comparative example 3
Example 2 was repeated, with the only difference that: the super-gravity rotary packed bed non-premixed interface is used for feeding, and the particle size of the prepared nano gold particles is larger, and the particle size distribution range is wider.
Comparative example 4
The preparation method of the nano gold particles used as the electron microscope developer specifically comprises the following steps:
1g of chloroauric acid is dissolved in deionized water to prepare 25mM chloroauric acid solution, and the solution is stored at 4 ℃ in a dark place; using sodium citrate as a stabilizer, dissolving 29.41mg sodium citrate (0.1 mmol) in 98mL of deionized water to obtain a sodium citrate solution (namely a stabilizer solution), adding 2mL of 25mM chloroauric acid solution into the sodium citrate solution, and fully stirring and mixing to obtain a precursor solution, wherein the molar ratio of sodium citrate to chloroauric acid in the precursor solution is 2:1.
Starting a super-gravity rotary packed bed, and regulating the rotating speed to 1000rpm; starting a feed pump, regulating the feed flow rate to be 25.4L/h, simultaneously conveying a precursor solution and a sodium borohydride solution (the molar ratio of chloroauric acid in the precursor solution to sodium borohydride in the sodium borohydride solution is 1:4) from a premixing interface into a rotary packed bed, performing oxidation-reduction reaction at normal temperature and normal pressure, instantly completing the reaction, discharging, repeatedly centrifuging, washing with deionized water, and removing redundant sodium citrate solution to obtain the gold nanoparticle dispersion liquid.
Fig. 16 is a transmission electron microscope image of the nano gold particles prepared in this example, and it can be seen that the nano gold particles have an irregular morphology and general dispersibility.
It should be understood that the foregoing examples of the present invention are provided merely for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention, and that various other changes and modifications may be made therein by one skilled in the art without departing from the spirit and scope of the present invention as defined by the appended claims.
Claims (3)
1. The preparation method of the nano gold particles used as the electron microscope developer is characterized in that chloroauric acid is used as a precursor material, cetyltrimethylammonium bromide is used as a stabilizer, sodium borohydride is used as a reducing agent, and oxidation-reduction reaction is carried out in a supergravity rotating packed bed to obtain the nano gold particles; the preparation method comprises the following steps:
dissolving chloroauric acid in water to obtain chloroauric acid solution;
dissolving cetyl trimethyl ammonium bromide in water to obtain a stabilizer solution, dropwise adding a chloroauric acid solution into the stabilizer solution, and stirring and mixing to obtain a precursor solution;
dissolving sodium borohydride in water to obtain sodium borohydride solution;
conveying the precursor solution and the sodium borohydride solution into a hypergravity rotating packed bed for oxidation-reduction reaction, centrifuging and washing to obtain a gold nanoparticle dispersion liquid;
wherein the feeding flow rate of the super-gravity rotary packed bed is 11.8-30.0L/h;
the feeding interface of the super-gravity rotary packed bed adopts premixing;
the molar ratio of hexadecyl trimethyl ammonium bromide to chloroauric acid in the precursor solution is 100:1;
the molar ratio of the sodium borohydride to the chloroauric acid is 4:1;
the rotor speed of the super gravity rotary packed bed is 1000rpm.
2. The nano-gold particles prepared by the preparation method of the nano-gold particles as an electron microscope developer according to claim 1.
3. The nano-gold particles according to claim 2, wherein the particle size of the nano-gold particles is 1-3nm.
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