Device and method for measuring solubility product of trace actinide colloid

Abstract

The invention discloses a device and a method for measuring the solubility product of trace actinide colloids. The device comprises a nitrogen gas cylinder and a small plastic bottle. According to the device and the method for measuring the solubility product of the trace actinide colloid, a set of experimental device which can stably release ammonia gas, is used for generating An (OH) 4 (am) colloid through acid-base titration and can capture a colloid generation critical point in a system is designed, only the concentration of hydrogen ions in a solution is changed, and the concentration of An4 + is not changed, so that single-factor control is facilitated; the gas phase titration process is slower than the traditional liquid phase titration process, and the slow change and accurate control of the pH value of the solution to be titrated can be realized; the concentration of the ammonia gas introduced into the titration system can be adjusted in various modes, so that low-concentration ammonia gas sample introduction can be realized; ammonia molecules are blown into an acidic thorium nitrate (plutonium nitrate) system in the form of bubbles, and are stirred by a magnetic stirrer, so that the acid-base reaction is more sufficient; an asymmetric flow field separation instrument and a matched ultraviolet and visible absorption spectrometer are combined with a mass spectrometer under the extremely low colloid concentration to enrich and observe the colloid, and the critical point of actinide colloid generation is accurately obtained.

Description

Technical Field

[0001] The present invention relates to the field of synthesis and characterization of actinide colloids, in particular to a device and a method for measuring the solubility product of trace actinide colloids. Background Art

[0002] Colloids refer to suspended particles with a particle size between 1nm and 1μm. They are divided into natural colloids and artificially synthesized colloids according to their source. They are essentially nanoparticles. Colloids have a large specific surface area and can carry a variety of ions for migration. Observations at the Nevada Test Site show that plutonium in groundwater can migrate up to 1.3km after being carried by colloids, increasing the safety risk of the site. Many laboratory studies have shown that plutonium, thorium and other An 4+ In addition to combining with natural colloids in the environment to form "pseudocolloids", it can also form "true colloids" including An(OH)4(am) and AnO2xH2O(s) through hydrolysis reactions, and the An in the system 4+ Concentration and pH are key influencing factors. Previous safety assessments of radioactive contaminated sites failed to consider the effect of colloid loading on nuclide migration, leading to significant inaccuracies in predictions. Therefore, understanding the solubility products and water environmental chemistry of colloids formed by tetravalent nuclides such as plutonium, thorium, uranium, and neptunium is crucial for clarifying their environmental fate and conducting nuclear environmental safety assessments of radioactive contaminated sites.

[0003] An 4+ It is very easy to hydrolyze, and the An(OH)4(am) and AnO2xH2O(s) formed are difficult to distinguish. Studies have found that AnO2xH2O(s) is generated at a higher pH and has a smaller solubility product. Due to limitations in research methods, there is currently a lack of reliable data on the solubility product of An(OH)4(am). There are reports that 1.2×10 -2 ~1×10 -5 The thorium solution of 10 moL / L was titrated to pH 2.7-4.5, and the formation of Th(OH)4 colloid was observed by laser-induced breakdown detection (LIBD). 4+ The solubility product was calculated based on the concentration and pH. However, the reliability of the results lacks verification by other research methods; in addition, the 4+ The concentration is much lower than 1.2×10 -2 ~1×10 -5 moL / L, the existing research conclusions are not suitable for generalization.

[0004] Before studying colloid properties, colloid generation is necessary. Previous studies of plutonium hydroxide and thorium hydroxide have typically employed the method of dropwise addition of sodium hydroxide solution to a hydrochloric acid-sodium chloride system containing thorium nitrate (plutonium nitrate), controlling the pH of the system to generate thorium hydroxide (plutonium hydroxide) colloids. However, this method has several drawbacks: changes in the liquid phase volume, which in turn causes variations in the thorium (plutonium) ion concentration, hinders single-factor control; and precise control of the system pH is difficult, as excessive sodium hydroxide addition can easily exceed the preset pH value.

[0005] The asymmetric flow field-flow fraction (AF4) uses the differences in the diffusion properties of particles of different sizes in a flow field to enrich and separate them. Its accompanying detectors (UV-visible absorption spectrometer and multi-angle laser light scattering instrument) detect the concentration of the separated particles. It can be regarded as a "chromatograph without a column." Therefore, it has the advantages of mild separation conditions and fine particle size classification intervals. The specific working principle is as follows: Figure 1 shown.

[0006] Based on the above background, the present invention proposes improvement schemes for the two links of colloid synthesis and colloid solubility product measurement, respectively, to improve the traditional method of adding alkali solution and the colloid solubility product measurement method to facilitate the experiment and accurately obtain the "critical point" of actinide colloid formation. Summary of the Invention

[0007] The purpose of the present invention is to provide a device and a method for measuring the solubility product of trace actinide colloids, to establish an experimental device that can stably introduce ammonia, control the reaction conditions for the formation of An(OH)4(am) colloids, and capture the critical point of colloid formation, to solve the difficult problems of precise control of trace colloid formation conditions and solubility product measurement, and to solve the problems raised in the above-mentioned background technology.

[0008] To achieve the above object, the present invention provides the following technical solutions: A device for measuring the solubility product of trace actinide colloids comprises a nitrogen gas cylinder, wherein the gas outlet of the nitrogen gas cylinder is respectively connected to a first gas path and a second gas path through a three-way pipe, the first gas path and the second gas path both comprise a mass flow controller, a large plastic bottle, an anti-backflow bottle and a three-necked flask, the openings of the large plastic bottle and the anti-backflow bottle are respectively equipped with a first bottle cap and a second bottle cap, a small plastic bottle is arranged in the large plastic bottle, and the opening of the small plastic bottle is threadedly connected to a third bottle cap, the gas inlet end of the mass flow controller is connected to the corresponding port of the three-way pipe, and the gas outlet end of the mass flow controller is connected to the corresponding port of the three-way pipe. A first connecting tube is connected, one end of the first connecting tube is inserted into the first bottle cap, a second connecting tube is provided between the first bottle cap and the second bottle cap, both ends of the second connecting tube are respectively inserted into the first bottle cap and the second bottle cap, stoppers are provided on the three ports of the three-necked flask, the second bottle cap is also fixedly connected with a third connecting tube, one end of the third connecting tube is inserted into a port on one side of the three-necked flask and extends to the inner side of its bottom, a pH online measuring instrument probe is inserted into the top port of the three-necked flask, small holes are evenly opened on the third bottle cap, ammonia solution is provided in the small plastic bottle, and An is provided in the three-necked flask of the first gas path. 4+ The three-necked flask of the second gas circuit is provided with a blank solution having the same pH as that of the solution in the three-necked flask of the first gas circuit.

[0009] As a further solution of the present invention: the concentration of the ammonia water is 30%, the volume of the small plastic bottle is 20 mL, and the amount of the ammonia water is 0-20 mL.

[0010] As a further solution of the present invention: the diameter of the small holes is 3 mm, and the number of the small holes is 2 to 5.

[0011] As a further solution of the present invention: the volume of the large plastic bottle and the anti-backflow bottle are both 500 mL, and the anti-backflow bottle is used to prevent the liquid in the three-necked flask from flowing into the ammonia permeation system along the pipeline when the nitrogen gas flow stops suddenly.

[0012] As a further solution of the present invention: the control speed of the mass flow controller is 1 to 20 mL / min.

[0013] As a further solution of the present invention: a magnetic stirrer is provided at the bottom of the three-necked flask, a matching rotor of the magnetic stirrer is arranged in the three-necked flask, and an exhaust valve is provided on the other side port in the three-necked flask.

[0014] As a further solution of the present invention: a method for measuring the solubility product of trace actinide colloids, the method steps are as follows: Step 1: Assemble the device. Connect the nitrogen cylinder to the first gas line and the second gas line through a tee. In the first gas line and the second gas line, the mass flow controller is connected to the tee and connected to the large plastic bottle through the first connecting pipe. The large plastic bottle is connected to the anti-backflow bottle through the second connecting pipe. The anti-backflow bottle is connected to the three-necked flask through the third connecting pipe. Screw the small plastic bottle containing ammonia water with the third bottle cap and place it in the large plastic bottle. Insert the pH online measuring instrument probe into the three-necked flask, and place the three-necked flask on a magnetic stirrer. Step 2: pH titration, the operating temperature is room temperature, room temperature is 15-20 ° C, the nitrogen cylinder releases nitrogen, adjusts the mass flow controller to adjust the nitrogen flow, and the nitrogen enters the large plastic bottle and carries the ammonia volatilized in the ammonia water through the anti-backflow bottle and then enters the three-necked flask. At this time, stir and mix under the action of a magnetic stirrer; Step 3: Select the carrier liquid: select the blank titrant in the three-necked flask on the second gas path as the carrier liquid; Step 4: Based on the AF4 separation program, set the flow rates of each AF4 pump to Tip flow = 0.5 mL / min, Focus flow = 3.5 mL / min, Cross flow = 3 mL / min, and the separation time to 20 min; Step 5: Determine the wavelength of the UV-visible absorption spectrometer and determine the optimal absorption wavelength of the colloid through a full spectrum scan of UV-visible light. The range of the full spectrum scan of UV-visible light is 200-800nm.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention designs a set of experimental devices that can stably release ammonia gas, used for acid-base titration to generate An(OH)4(am) colloid, and can capture the critical point of colloid formation in the system, only changing the hydrogen ion concentration in the solution without changing the An(OH)4(am) colloid. 4+ The concentration of ammonia is low, which is conducive to single-factor control; the gas phase titration process is slower than traditional liquid phase titration, which can achieve slow changes and precise control of the pH value of the titrated solution; the concentration of ammonia introduced into the titration system can be adjusted in a variety of ways, which can achieve low-concentration ammonia injection; the reaction is more complete, ammonia molecules are bubbled into the acidic thorium nitrate (plutonium nitrate) system in the form of bubbles, and stirring with a magnetic stirrer can ensure a more complete acid-base reaction; using AF4 and its supporting UV-visible absorption spectrometer for enrichment and observation, the "critical point" of actinide colloid formation is accurately obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the working principle of the AF4 separation channel.

[0017] Figure 2 The figure is a schematic diagram of the structure of a device and method for measuring the solubility product of trace actinide colloids.

[0018] Figure 3 This is a diagram showing the third bottle cap in a device and method for measuring the solubility product of trace actinide colloids.

[0019] In the figure: 1. Nitrogen cylinder; 2. T-tube; 3. First gas line; 4. Second gas line; 5. Mass flow controller; 6. Large plastic bottle; 7. Anti-backflow bottle; 8. Three-necked flask; 9. First bottle cap; 10. Second bottle cap; 11. Small plastic bottle; 12. Third bottle cap; 13. First connecting pipe; 14. Second connecting pipe; 15. Stopper; 16. Third connecting pipe; 17. pH online measuring instrument probe; 18. Small hole; 19. Magnetic stirrer. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] See also Figures 1 to 3 In an embodiment of the present invention, a device and method for measuring the solubility product of trace actinide colloids are provided, comprising a nitrogen cylinder 1, wherein the gas outlet of the nitrogen cylinder 1 is connected to a first gas path 3 and a second gas path 4 respectively through a three-way pipe 2, the first gas path 3 and the second gas path 4 each comprising a mass flow controller 5, a large plastic bottle 6, an anti-backflow bottle 7 and a three-necked flask 8, the openings of the large plastic bottle 6 and the anti-backflow bottle 7 are respectively provided with a first bottle cap 9 and a second bottle cap 10, a small plastic bottle 11 is provided in the large plastic bottle 6, the opening of the small plastic bottle 11 is threadedly connected with a third bottle cap 12, the gas inlet end of the mass flow controller 5 is connected to the corresponding port of the three-way pipe 2, and the gas outlet end of the mass flow controller 5 The end is connected to a first connecting tube 13, one end of the first connecting tube 13 is inserted into the first bottle cap 9, a second connecting tube 14 is provided between the first bottle cap 9 and the second bottle cap 10, both ends of the second connecting tube 14 are respectively inserted into the first bottle cap 9 and the second bottle cap 10, three ports of the three-necked flask 8 are provided with stoppers 15, the second bottle cap 10 is also fixedly connected to a third connecting tube 16, one end of the third connecting tube 16 is inserted into a port on one side of the three-necked flask 8 and extends to the inner side of its bottom, a pH online measuring instrument probe 17 is inserted into the top port of the three-necked flask 8, small holes 18 are evenly opened on the third bottle cap 12, ammonia solution is provided in the small plastic bottle 11, and An is provided in the three-necked flask 8 of the first gas path 3. 4+ The sodium chloride-hydrochloric acid solution is provided in the three-necked flask 8 of the second gas path 4, and a blank solution having the same pH as the solution in the three-necked flask 8 of the first gas path 3 is provided.

[0022] The concentration of the ammonia solution is 30%, the volume of the small plastic bottle 11 is 20 mL, and the amount of the ammonia solution is 0-20 mL.

[0023] The diameter of the small holes 18 is 3 mm, and the number of the small holes 18 is 2 to 5.

[0024] The volume of the large plastic bottle 6 and the anti-backflow bottle 7 are both 500 mL. The anti-backflow bottle 7 is used to prevent the liquid in the three-necked flask 8 from flowing into the ammonia permeation system along the pipeline when the nitrogen gas flow stops suddenly.

[0025] The control speed of the mass flow controller 5 is 1 to 20 mL / min.

[0026] A magnetic stirrer 19 is provided at the bottom of the three-necked flask 8 , and a matching rotor of the magnetic stirrer 19 is arranged in the three-necked flask 8 . An exhaust valve is provided on the other side port in the three-necked flask 8 .

[0027] A method for measuring the solubility product of trace actinide colloids, the method steps are as follows: Step 1: Assembling the device: the nitrogen cylinder 1 is connected to the first gas line 3 and the second gas line 4 through the three-way pipe 2. In the first gas line 3 and the second gas line 4, the mass flow controller 5 is connected to the three-way pipe 2 and communicated with the large plastic bottle 6 through the first connecting pipe 13. The large plastic bottle 6 is connected to the anti-backflow bottle 7 through the second connecting pipe 14. The anti-backflow bottle 7 is connected to the three-necked flask 8 through the third connecting pipe 16. The small plastic bottle 11 containing ammonia water is screwed with the third bottle cap 12 and placed in the large plastic bottle 6. The pH online measuring instrument probe 17 is inserted into the three-necked flask 8. The three-necked flask 8 is placed on the magnetic stirrer 19. Step 2: pH titration, the operating temperature is room temperature, which is 15-20°C. The nitrogen cylinder 1 releases nitrogen, and the mass flow controller 5 is adjusted to adjust the nitrogen flow. After the nitrogen enters the large plastic bottle 6, it carries the ammonia volatilized in the ammonia water through the anti-backflow bottle 7 and enters the three-necked flask 8. At this time, stirring and mixing are carried out under the action of the magnetic stirrer 19; Step 3: Selecting a carrier liquid: Select the blank titrant in the three-necked flask 8 on the second gas line 4 as the carrier liquid; Step 4: Based on the AF4 separation program, set the flow rates of each AF4 pump to Tip flow = 0.5 mL / min, Focus flow = 3.5 mL / min, Cross flow = 3 mL / min, and the separation time to 20 min; Step 5: Determine the wavelength of the UV-visible absorption spectrometer and determine the optimal absorption wavelength of the colloid through a full spectrum scan of UV-visible light. The range of the full spectrum scan of UV-visible light is 200-800nm.

[0028] The basic principle of work: 4+The hydrolysis of ammonia is used as an implementation case. Ammonia water is very volatile. The ammonia gas accumulated above the container is carried by the nitrogen gas upstream, passes through the anti-backflow bottle, and enters the hydrochloric acid-sodium chloride solution of thorium nitrate (plutonium nitrate), neutralizes the hydrogen ions therein, and adjusts the pH of the system. The pH value of the hydrochloric acid-sodium chloride solution of thorium nitrate (plutonium nitrate) in the three-necked flask 8 is selected to be pH=2.

[0029] Nitrogen from nitrogen cylinder 1, after being regulated by mass flow controller 5, enters the subsequent pipeline. As ammonia in small plastic bottle 11 evaporates, it diffuses upward through small holes 18 in third bottle cap 12, where it is carried by nitrogen gas flowing upstream in the pipeline. Nitrogen acts as a carrier gas, carrying the ammonia into three-necked flask 8. The ammonia reacts with the hydrogen ions in three-necked flask 8 to produce an acid-base neutralization reaction. To ensure a more complete reaction, the solution in the three-necked flask is continuously stirred using a magnetic stirrer 19.

[0030] Control of ammonia injection volume: The nitrogen flow rate was adjusted to control the ammonia injection volume. Three nitrogen flow rates were set: low (1 mL / min), medium (10 mL / min), and high (20 mL / min). The pH changes in the solution in the three-necked flask under these three nitrogen flow rates varied significantly, with the pH increase rate showing the order: low flow rate < medium flow rate < high flow rate. This demonstrates that adjusting the nitrogen flow rate allows for excellent control of the ammonia injection volume.

[0031] Control is performed through the small plastic bottle 11. Experimentally adjust the number of small holes 18 on the third bottle cap 12. The more small holes 18 on the third bottle cap 12, the more ammonia volatilized from the ammonia water, and the faster the pH rises. Experimentally adjust the amount of ammonia water added to the small plastic bottle 11. The more ammonia water added, the more ammonia volatilized. Experimentally adjust the concentration of ammonia water in the small plastic bottle 11. The diameter of the small holes 18 can also be adjusted. The larger the opening, the faster the pH rises. The more ammonia volatilized from the ammonia water. The present invention uses about 30% ammonia water, which can be adjusted according to specific needs. Subsequently, you can try to achieve this by controlling the temperature of the ammonia permeation bottle. Generally speaking, the volatilization rate of ammonia in ammonia water increases with increasing temperature.

[0032] A method for measuring the solubility product of trace actinide colloids, the method steps are as follows: Step 1: Assembling the device: the nitrogen cylinder 1 is connected to the first gas line 3 and the second gas line 4 through the three-way pipe 2. In the first gas line 3 and the second gas line 4, the mass flow controller 5 is connected to the three-way pipe 2 and communicated with the large plastic bottle 6 through the first connecting pipe 13. The large plastic bottle 6 is connected to the anti-backflow bottle 7 through the second connecting pipe 14. The anti-backflow bottle 7 is connected to the three-necked flask 8 through the third connecting pipe 16. The small plastic bottle 11 containing ammonia water is screwed with the third bottle cap 12 and placed in the large plastic bottle 6. The pH online measuring instrument probe 17 is inserted into the three-necked flask 8. The three-necked flask 8 is placed on the magnetic stirrer 19. Step 2: pH titration, the operating temperature is room temperature, which is 15-20°C. The nitrogen cylinder 1 releases nitrogen, and the mass flow controller 5 is adjusted to adjust the nitrogen flow. After the nitrogen enters the large plastic bottle 6, it carries the ammonia volatilized in the ammonia water through the anti-backflow bottle 7 and enters the three-necked flask 8. At this time, stirring and mixing are carried out under the action of the magnetic stirrer 19; Step 3: Selecting a carrier liquid: Select the blank titrant in the three-necked flask 8 on the second gas line 4 as the carrier liquid; Step 4: Based on the AF4 separation program, set the flow rates of each AF4 pump to Tip flow = 0.5 mL / min, Focus flow = 3.5 mL / min, Cross flow = 3 mL / min, and the separation time to 20 min; Step 5: Determine the wavelength of the UV-visible absorption spectrometer. After scanning the full spectrum of UV-visible light, determine the optimal absorption wavelength of the colloid. The range of the UV-visible light full spectrum scanning is 200-800nm. It is determined that the optimal absorption wavelength of Th colloid is 280nm, so Th +4 The wavelength of the UV-visible absorption spectrometer was set at 280 nm.

[0033] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A device for measuring the solubility product of trace actinide colloids, comprising a nitrogen gas cylinder (1), characterized in that: The gas outlet of the nitrogen cylinder (1) is connected to a first gas path (3) and a second gas path (4) through a three-way pipe (2), respectively. The first gas path (3) and the second gas path (4) both include a mass flow controller (5), a large plastic bottle (6), an anti-backflow bottle (7) and a three-necked flask (8). The openings of the large plastic bottle (6) and the anti-backflow bottle (7) are respectively installed with a first bottle cap (9) and a second bottle cap (10). The large plastic bottle (6) is provided with a small plastic bottle (11). The opening of the small plastic bottle (11) is threadedly connected with a third bottle cap (12). The gas inlet end of the mass flow controller (5) is connected to the corresponding port of the three-way pipe (2). The gas outlet end of the mass flow controller (5) is connected to a first connecting pipe (13). The first connecting pipe (14) is connected to the first connecting pipe (15). One end of the tube (13) is inserted into the first bottle cap (9), a second connecting tube (14) is provided between the first bottle cap (9) and the second bottle cap (10), and both ends of the second connecting tube (14) are respectively inserted into the first bottle cap (9) and the second bottle cap (10), three ports of the three-necked flask (8) are provided with stoppers (15), the second bottle cap (10) is also fixedly connected with a third connecting tube (16), one end of the third connecting tube (16) is inserted into a port on one side of the three-necked flask (8) and extends to the inner side of the bottom thereof, a pH online measuring instrument probe (17) is inserted into the top port of the three-necked flask (8), small holes (18) are evenly opened on the third bottle cap (12), ammonia solution is provided in the small plastic bottle (11), An 4+ A sodium chloride-hydrochloric acid solution is provided in the three-necked flask (8) of the second gas path (4), and a blank solution having the same pH as that of the solution in the three-necked flask (8) of the first gas path (3) is provided in the three-necked flask (8).

2. The device for measuring the solubility product of trace actinide colloids according to claim 1, wherein: The concentration of the ammonia water is 30%, the volume of the small plastic bottle (11) is 20 mL, and the amount of the ammonia water is 0-20 mL.

3. The device for measuring the solubility product of trace actinide colloids according to claim 1, wherein: The aperture of the small holes (18) is 3 mm, and the number of the small holes (18) is 2 to 5.

4. The device for measuring the solubility product of trace actinide colloids according to claim 1, wherein: The volume of the large plastic bottle (6) and the anti-suction bottle (7) is 500 mL.

5. The device for measuring the solubility product of trace actinide colloids according to claim 1, wherein: The control speed of the mass flow controller (5) is 1 to 20 mL / min.

6. The device for measuring the solubility product of trace actinide colloids according to claim 1, characterized in that: A magnetic stirrer (19) is provided at the bottom of the three-necked flask (8), a matching rotor of the magnetic stirrer (19) is arranged in the three-necked flask (8), and an exhaust valve is provided on the other side port in the three-necked flask (8).

7. A method for measuring the solubility product of trace actinide colloids, characterized by: The method steps are as follows: Step 1: Assembling the device, the nitrogen cylinder (1) is connected to the first gas path (3) and the second gas path (4) through a three-way pipe (2), in the first gas path (3) and the second gas path (4), a mass flow controller (5) is connected to the three-way pipe (2) and communicated with the large plastic bottle (6) through a first connecting pipe (13), the large plastic bottle (6) is communicated with the anti-backflow bottle (7) through a second connecting pipe (14), the anti-backflow bottle (7) is communicated with the three-necked flask (8) through a third connecting pipe (16), a small plastic bottle (11) containing ammonia water is screwed on the third bottle cap (12) and then placed in the large plastic bottle (6), a pH online measuring instrument probe (17) is inserted into the three-necked flask (8), and the three-necked flask (8) is placed on a magnetic stirrer (19); Step 2: pH titration, nitrogen is released from the nitrogen cylinder (1), and the mass flow controller (5) is adjusted to adjust the nitrogen flow rate. The nitrogen enters the large plastic bottle (6) and carries the ammonia volatilized in the ammonia water through the anti-backflow bottle (7) and then enters the three-necked flask (8), at which time the mixture is stirred and mixed under the action of the magnetic stirrer (19); Step 3: Selection of carrier liquid for the asymmetric flow field separator: select the blank titrant in the three-necked flask (8) on the second gas path (4) as the carrier liquid; Step 4: Based on the separation program of the asymmetric flow field separator, set the flow rates of each pump to Tip flow = 0.5 mL / min, Focus flow = 3.5 mL / min, Cross flow = 3 mL / min, and the separation time to 20 min; Step 5: Determine the wavelength of the UV-visible absorption spectrometer and determine the optimal absorption wavelength of the colloid by scanning the entire UV-visible spectrum.

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