An active microchannel extraction system for enhancing mass transfer in cavity extrusion extraction

Abstract

The present invention relates to the technical field of microchannel extraction, and discloses an active microchannel extraction system for enhancing mass transfer by cavity extrusion, which includes a sample injection device, a microchannel device for enhancing mass transfer, a temperature control and monitoring device, a flow pattern monitoring device, and a sample data acquisition and measurement device. The microchannel device for enhancing mass transfer includes a linear motor, a microchannel housing, and a reciprocating plate assembly. The reciprocating plate assembly is slidably arranged on the inner bottom wall of the microchannel housing. A linear motor is arranged on one side of the microchannel housing, and the linear motor is used to drive the reciprocating plate assembly to reciprocate. The reciprocating plate assembly includes a middle rectangular parallelepiped plate and side rectangular parallelepiped plates. Side rectangular parallelepiped plates are arranged on both sides of the middle rectangular parallelepiped plate. A micron-level channel is formed between the side rectangular parallelepiped plates and the side walls of the microchannel housing, and a channel slit is formed between the side rectangular parallelepiped plates and the middle rectangular parallelepiped plate. It solves the problems existing in improving the mass transfer and separation efficiency of passive microchannels through internal geometric structure optimization.

Description

Technical Field

[0001] The present invention relates to the technical field of microchannel extraction, and particularly to an active microchannel extraction system with enhanced mass transfer by cavity extrusion extraction. Background Art

[0002] The booming development of the lithium-ion battery industry and its intensive and large-scale applications have brought great convenience to our lives. However, the accumulation of a large number of waste batteries and unreasonable recycling have brought many major challenges such as environmental pollution and resource waste. From the perspective of sustainable development, the recycling and reuse of waste lithium-ion batteries are of great significance, especially the recycling value of metal elements such as nickel, cobalt, and manganese as key functional materials in the cathode material is extremely high. In the field of recovery and separation of valuable and resource-based metal ions, the liquid-liquid extraction method has played a huge role.

[0003] In recent years, the development of microchannel technology has demonstrated excellent performance in many fields and has attracted the attention of many researchers. Liquid-liquid extraction is also one of its potential applications. Compared with traditional extractors, microchannel extraction has its inherent advantages (such as forming tiny liquid droplets based on the size effect; increasing the effective mass transfer specific surface area and improving the mass transfer coefficient; shortening the mass transfer distance and mass transfer time; using less extractant and having a fast extraction reaction rate, etc.), making it play a huge role in the field of liquid-liquid extraction. However, the fluid flow in the microchannel is generally laminar, and the main way of intermolecular transfer is molecular diffusion, resulting in a limited mass transfer rate. In addition to the above factors, the performance of the microchannel for liquid-liquid extraction also depends on the physical properties of the two phases involved, because factors such as density, viscosity, and interfacial tension affect droplet dispersion in the channel and the mass transfer coefficient at the liquid surface, etc. Therefore, researching how to improve microchannel mass transfer enhancement and developing new microchannel devices are very potential research directions.

[0004] There are mainly two effective ways to enhance the mass transfer between fluids in the microchannel: active enhancement and passive enhancement. Among them, active enhancement is achieved by applying an external field, such as gas-liquid two-phase flow enhancement, oscillating field enhancement (ultrasonic field, microwave, etc.) and the combination of different enhancement methods, etc. Passive enhancement is achieved by changing the channel structure or adding obstacles in the channel, such as optimizing the microchannel geometric structure, interfacial modification technology, etc. Microchannels with different enhancement methods can all achieve excellent mass transfer enhancement performance, but due to the size of the microchannel device being in the micron range, it is very difficult to improve the mass transfer separation efficiency through the internal geometric structure optimization of the microchannel. Therefore, designing and developing active enhancement microreactors also have broad application prospects and research value. Summary of the Invention

[0005] The object of the present invention is to overcome the deficiencies of the prior art and provide an active microchannel extraction system for enhancing mass transfer by cavity extrusion extraction, which is used to solve the problems existing in improving the mass transfer and separation efficiency of passive microchannels through internal geometric structure optimization.

[0006] The object of the present invention is achieved by the following technical solutions: an active microchannel extraction system for enhancing mass transfer by cavity extrusion extraction, comprising a sample injection device, an extraction mass transfer enhancement microchannel device, a temperature control and monitoring device, a flow pattern monitoring device, and a sample data acquisition and measurement device. The extraction mass transfer enhancement microchannel device includes a linear motor, a microchannel housing, and a reciprocating plate assembly. The reciprocating plate assembly is slidably arranged on the inner bottom wall of the microchannel housing. The linear motor is arranged on one side of the microchannel housing, and the output shaft of the linear motor penetrates into the microchannel housing and is connected to the reciprocating plate assembly. The reciprocating plate assembly includes a middle rectangular plate and side rectangular plates. Side rectangular plates are arranged on both sides of the middle rectangular plate. A micron-scale channel is formed between the side rectangular plates and the side walls of the microchannel housing, and a channel slit is formed between the side rectangular plates and the middle rectangular plate.

[0007] The sample injection device includes an aqueous phase injection pump, an organic phase injection pump, and a T-shaped three-way valve. The aqueous phase injection pump is connected to an input port of the T-shaped three-way valve through an aqueous phase injection tube, and the organic phase injection pump is connected to another input port of the T-shaped three-way valve through an organic phase injection tube. The output port of the T-shaped three-way valve is connected to the top of one end of the microchannel housing through an injection tube. The bottom of the other end of the microchannel housing is connected to a sample output tube, and the sample output tube is connected to the sample data acquisition and measurement device. The flow pattern monitoring device is used to record the flow states of the oil-water two-phase flowing into and out of the microchannel housing under different experimental conditions.

[0008] The temperature control and monitoring device is connected to the microchannel housing and is used to adjust the extraction temperature inside the microchannel housing.

[0009] In some embodiments, the temperature control and monitoring device includes a constant temperature water bath, a peristaltic pump, a high-precision contact thermometer, and a temperature sensor. The water outlet of the constant temperature water bath is connected to the input port of the peristaltic pump. The output port of the peristaltic pump is connected to a spiral coil, and the spiral coil is sleeved on the microchannel housing. The temperature sensor is arranged inside the microchannel housing, and the output wire of the temperature sensor penetrates out of the microchannel housing and is connected to the high-precision contact thermometer.

[0010] In some embodiments, the sample data acquisition and measurement device includes an oil-water separation device and an atomic absorption spectrometer. The sample output tube is connected to the oil-water separation device, and the water phase outlet of the oil-water separation device is connected to the atomic absorption spectrometer.

[0011] In some embodiments, two sets of the flow pattern monitoring devices are provided, and the two sets of flow pattern monitoring devices are respectively arranged at the sample inlet pipe and the sample outlet pipe. The flow pattern monitoring device includes a 360° light source and a high-speed high-definition imaging camera, and the 360° light source is arranged on one side of the high-speed high-definition imaging camera.

[0012] In some embodiments, rectangular protrusions are fixed on both sides of the middle rectangular plate, a rectangular groove is formed on one side of the side rectangular plate close to the middle rectangular plate, the rectangular protrusion is arranged in the rectangular groove, and a channel slit is formed between the rectangular protrusion and the rectangular groove. The side rectangular plate has the freedom to move away from or close to the middle rectangular plate to change the size of the channel slit.

[0013] In some embodiments, elastic sealing gaskets are fixed on both sides of the middle rectangular plate at the positions of the rectangular protrusions, and the elastic sealing gaskets are in a compressed state and in contact with the side rectangular plate.

[0014] In some embodiments, the extraction mass transfer intensification microchannel device further includes a bidirectional lead screw and a bushing. The bushing is rotatably sleeved in the middle of the bidirectional lead screw, and the bushing is fixedly arranged in the middle rectangular plate. The two side rectangular plates are respectively threadedly sleeved on two thread segments with opposite rotations of the bidirectional lead screw.

[0015] In some embodiments, a limiting protrusion is fixed on the inner bottom wall of the microchannel housing, a limiting groove is formed at the bottom of the middle rectangular plate, the limiting protrusion is fitted in the limiting groove, and the bottom wall of the side rectangular plate is in close contact with the inner bottom wall of the microchannel housing.

[0016] In some embodiments, an adjustment hole is formed in the side wall of the microchannel housing. When one end of the reciprocating plate assembly abuts against the microchannel housing, the adjustment hole corresponds to one end of the bidirectional lead screw, and an internal hexagonal groove is formed at one end of the bidirectional lead screw close to the adjustment hole;

[0017] The adjustment hole includes a large-diameter hole and a small-diameter threaded hole arranged in sequence along the direction close to the reciprocating plate assembly. A threaded post is threadedly fitted in the small-diameter threaded hole, a sealing disc is arranged in the large-diameter hole, the threaded post is fixedly connected to the sealing disc, a sealing gasket is sleeved on the threaded post, and the sealing gasket is in a compressed state and abuts against the step formed by the large-diameter hole and the small-diameter threaded hole.

[0018] In some embodiments, a circular angle scale is arranged on the step, and the circular angle scale is coaxially arranged with the large-diameter hole.

[0019] The beneficial effects of the present invention are:

[0020] 1. It overcomes and solves the problems existing in the fabrication of passive microchannels, realizes the goal of mass transfer enhancement for the extraction and separation of metal ions through both static and dynamic aspects of the reciprocating plate assembly, and provides a potential case for understanding the extraction mass transfer characteristics of metal ions in active microchannels.

[0021] 2. The manufacturing process is simple, and based on the structural design of the device, it is easy to scale up or down to meet the needs of different experiments or applications.

[0022] 3. Due to the excellent performance of mass transfer enhancement during the extraction and separation process, it can efficiently recover precious metal ions in the cathode materials of waste lithium-ion batteries, realizing the recycling and reuse of resources. The research of the present invention in the field of recycling and reuse of precious metal ions in ternary lithium-ion batteries not only provides theoretical support for the efficient recycling of lithium-ion batteries, but also has practical significance for the development and design of new microchannels.

[0023] 4. The device is simple to operate and has a wide range of uses. It can also be applied to the research of other microreactions or microreactors, and has broad application prospects.

[0024] 5. The channel slit size between the middle rectangular plate and the side rectangular plate can be adjusted to adjust the extraction with different sizes of channel slits, and experiments with different sizes of channel slits can be carried out to obtain the optimal channel slit size for different oil-water two phases. The optimal channel slit size is used for extraction adaptation, combined with active mass transfer enhancement, to further improve the extraction efficiency and extraction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of an active microchannel extraction system for cavity extrusion type extraction mass transfer enhancement according to the present invention;

[0026] Figure 2 It is a cross-sectional view of the microchannel housing in an active microchannel extraction system for cavity extrusion type extraction mass transfer enhancement according to the present invention;

[0027] Figure 3 It is a front view of the microchannel in an active microchannel extraction system for cavity extrusion type extraction mass transfer enhancement according to the present invention;

[0028] Figure 4 is Figure 3 the sectional view taken along the line A-A in

[0029] Figure 5 is Figure 4 the enlarged view at A in

[0030] Figure 6 It is the influence of different injection rates on the extraction efficiency of Mn(II) and the pH of the aqueous phase before and after the experiment of the present invention;

[0031] Figure 7 For the influence of the movement rates of different reciprocating plate assemblies of the present invention on the extraction efficiency of Mn(II) and the pH of the aqueous phase before and after the experiment;

[0032] In the figure, 1 - sample injection device, 2 - extraction mass transfer enhancement microchannel device, 3 - temperature control and monitoring device, 4 - flow pattern monitoring device, 5 - sample data acquisition and measurement device, 6 - linear motor, 7 - microchannel housing, 8 - middle rectangular plate, 9 - side rectangular plate, 10 - aqueous phase injection pump, 11 - organic phase injection pump, 12 - T-shaped three-way valve, 13 - aqueous phase injection tube, 14 - organic phase injection tube, 15 - injection tube, 16 - sample outlet tube, 17 - constant temperature water bath, 18 - peristaltic pump, 19 - high-precision contact thermometer, 20 - temperature sensor, 21 - spiral coil pipe, 22 - oil-water separation device, 23 - atomic absorption spectrometer, 24 - 360° light source, 25 - high-speed high-definition imaging camera, 26 - rectangular protrusion, 27 - rectangular groove, 28 - elastic gasket, 29 - bidirectional lead screw, 30 - bushing, 31 - limit protrusion, 32 - limit groove, 33 - internal hexagonal groove, 34 - large diameter hole, 35 - small diameter threaded hole, 36 - threaded post, 37 - sealing disc, 38 - sealing gasket. Specific embodiments

[0033] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0034] Example 1. As Figures 1 to 7As shown in the figure, an active microchannel extraction system for enhancing mass transfer in cavity extrusion extraction includes a sampling device, an extraction mass transfer enhancement microchannel device, a temperature control and monitoring device, a flow pattern monitoring device, and a sample data acquisition and measurement device. The extraction mass transfer enhancement microchannel device includes a linear motor 6, a microchannel housing 7, and a reciprocating plate assembly. The reciprocating plate assembly is slidably arranged on the inner bottom wall of the microchannel housing 7. A linear motor 6 is arranged on one side of the microchannel housing 7. The output shaft of the linear motor 6 penetrates into the microchannel housing 7 and is connected to the reciprocating plate assembly. The linear motor 6 drives the reciprocating plate assembly to reciprocate in the microchannel housing 7, which is beneficial to enhancing mass transfer. A sealing ring is arranged between the output shaft of the linear motor 6 and the microchannel housing 7 to ensure the seal at the connection between the linear motor 6 and the microchannel housing 7. The reciprocating plate assembly includes a middle rectangular plate 8 and side rectangular plates 9. Side rectangular plates 9 are arranged on both sides of the middle rectangular plate 8. A micron-level channel is formed between the side rectangular plates 9 and the side walls of the microchannel housing 7, and a channel slit is formed between the side rectangular plates 9 and the middle rectangular plate 8. The sampling device includes an aqueous phase sampling pump 10, an organic phase sampling pump 11, and a T-shaped three-way valve 12. The aqueous phase sampling pump 10 is connected to an input port of the T-shaped three-way valve 12 through an aqueous phase sampling tube 13. The organic phase sampling pump 11 is connected to another input port of the T-shaped three-way valve 12 through an organic phase sampling tube 14. The output port of the T-shaped three-way valve 12 is connected to the top of one end of the microchannel housing 7 through a sampling tube 15. The bottom of the other end of the microchannel housing 7 is connected to a sampling tube 16, and the sampling tube 16 is connected to the sample data acquisition and measurement device. The flow pattern monitoring device is used to record the flow states of the oil-water two-phase flowing into and out of the microchannel housing 7 under different experimental conditions. The temperature control and monitoring device is connected to the microchannel housing 7 and is used to adjust the extraction temperature in the microchannel housing 7. The temperature control and monitoring device includes a constant temperature water bath 17, a peristaltic pump 18, a high-precision contact thermometer 19, and a temperature sensor 20. The water outlet of the constant temperature water bath 17 is connected to the input port of the peristaltic pump 18. The output port of the peristaltic pump 18 is connected to a spiral coil 21, and the spiral coil 21 is sleeved on the microchannel housing 7. A temperature sensor 20 is arranged in the microchannel housing 7, and the output wire of the temperature sensor 20 penetrates out of the microchannel housing 7 and is connected to the high-precision contact thermometer 19. The sample data acquisition and measurement device includes an oil-water separation device 22 and an atomic absorption spectrometer 23. The sampling tube 16 is connected to the oil-water separation device 22, and the water phase outlet of the oil-water separation device 22 is connected to the atomic absorption spectrometer 23, which is used to calculate the mass transfer coefficient of the extraction mass transfer enhancement microchannel device during the extraction and separation process. There are two sets of flow pattern monitoring devices, which are respectively arranged at the sampling tube 15 and the sampling tube 16. The flow pattern monitoring device includes a 360° light source 24 and a high-speed high-definition imaging camera 25, and the 360° light source 24 is arranged on one side of the high-speed high-definition imaging camera 25;The specific experimental operations are as follows: Before the experiment starts, first, hot water is passed into the spiral coil 21 through the constant temperature water bath 17 and the peristaltic pump 18. The temperature of the spiral coil 21 is used to preheat the reciprocating plate assembly and maintain it at the temperature required for the experiment. The temperature is monitored in real time by the high-precision contact thermometer 19 and the temperature sensor 20. After the preheating is completed, the aqueous phase and the organic phase at the experimental temperature are loaded, and then they are pumped into the microchannel housing 7 from two opposite inlets of the T-shaped three-way valve 12 through the aqueous phase injection pump 10 and the organic phase injection pump 11 at a certain injection speed respectively. According to the design principle of the extraction mass transfer enhanced microchannel device: There are mainly two ways to enhance mass transfer: (1) In the static experiment, by using the size effect of the micron-sized channels formed between the long rectangular plate 9 on the side and the inner wall of the microchannel housing 7 and the channel slit between the middle rectangular plate 8 and the long rectangular plate 9 on the side, the oil and water phases can form tiny droplets, shortening the mass transfer distance and time and achieving a large oil-water contact area; (2) In the dynamic experiment, the reciprocating plate assembly is driven by the linear motor 6 to reciprocate. The extrusion effect of the reciprocating motion can promote the mixing and internal mixing of the oil phase and the aqueous phase in the cavity, further increasing the contact area between the oil and water phases in the micron-sized channels. In addition, the reciprocating motion also strengthens the interaction between the oil phase and the aqueous phase and the channel slit wall, which is beneficial to the enhancement of mass transfer. After the extraction mass transfer enhancement is completed, the oil and water phases flow out through the sampling tube 16. After the fluid flow state is stable, the flow states of the oil and water phases at the inlet and outlet of the microchannel housing 7 under different experimental conditions are respectively recorded by the high-speed high-definition imaging system with a 360° light source 24 for further analysis. After the aqueous phase separated by the oil-water separation device 22 is further processed, the concentration of metal ions in the aqueous phase is measured by the atomic absorption spectrometer 23 and then further analyzed. The organic phase separated by the oil-water separation device 22 is further analyzed after characterizing the changes in its functional groups by the Fourier transform infrared spectrometer (FTIR).;

[0035] Further, as Figure 2As shown in the figure, rectangular protrusions 26 are fixed on both sides of the middle rectangular parallelepiped plate 8. A rectangular groove 27 is formed on one side of the side rectangular parallelepiped plate 9 close to the middle rectangular parallelepiped plate 8. The rectangular protrusion 26 is arranged in the rectangular groove 27, and a channel slit is formed between the rectangular protrusion 26 and the rectangular groove 27. The side rectangular parallelepiped plate 9 has the freedom to move away from or close to the middle rectangular parallelepiped plate 8, which is used to change the size of the channel slit. By moving the side rectangular parallelepiped plate 9, the width dimension of the channel slit between the side rectangular parallelepiped plate 9 and the middle rectangular parallelepiped plate 8 is changed, and the size of the optimal channel slit under different oil-water two-phase conditions is studied to further enhance the mass transfer effect. Elastic gaskets 28 are fixed on both sides of the rectangular protrusion 26 of the middle rectangular parallelepiped plate 8. The elastic gaskets 28 are in a compressed state and in contact with the side rectangular parallelepiped plate 9. The elastic gaskets 28 are always arranged in a compressed state between the middle rectangular parallelepiped plate 8 and the side rectangular parallelepiped plate 9. By the deformation degree of the elastic gaskets 28, the change in the size of the channel slit is adapted. After the size of the channel slit is changed, good sealing performance is still maintained at the position of the non-channel slit between the middle rectangular parallelepiped plate 8 and the side rectangular parallelepiped plate 9, ensuring the stable flow of oil-water two-phase in the channel slit.

[0036] Furthermore, as Figures 2 to 5 shown, the extraction mass transfer enhanced microchannel device further includes a bidirectional lead screw 29 and a bushing 30. The bushing 30 is rotatably sleeved on the middle part of the bidirectional lead screw 29. The bushing 30 is fixedly penetrated in the middle rectangular parallelepiped plate 8. The two side rectangular parallelepiped plates 9 are respectively threadedly sleeved on the two oppositely rotating thread segments of the bidirectional lead screw 29. A limiting protrusion 31 is fixed on the inner bottom wall of the microchannel housing 7. A limiting groove 32 is formed at the bottom of the middle rectangular parallelepiped plate 8. The limiting protrusion 31 is fitted in the limiting groove 32. The bottom wall of the side rectangular parallelepiped plate 9 is in close contact with the inner bottom wall of the microchannel housing 7. By rotating the bidirectional lead screw 29, the two side rectangular parallelepiped plates 9 move closer to or away from the middle rectangular parallelepiped plate 8, so that the two side rectangular parallelepiped plates 9 move synchronously and in opposite directions, thereby synchronously regulating the sizes of the two channel slits. By the fitting of the limiting protrusion 31 and the limiting groove 32, the freedom of the middle rectangular parallelepiped plate 8 to move axially along the bidirectional lead screw 29 is restricted, so that when adjusting the size of the channel slit, the middle rectangular parallelepiped plate 8 can remain stable, ensuring the size regulation accuracy of the channel slit; since the size of the channel slit is very small, the lead screw regulation can meet the regulation requirements of the precision size of the channel slit.

[0037] Furthermore, as Figures 2 to 5As shown in the figure, an adjustment hole is provided on the side wall of the microchannel housing 7. When one end of the reciprocating plate assembly abuts against the microchannel housing 7, the adjustment hole corresponds to one end of the double-threaded lead screw 29. An internal hexagonal groove 33 is provided at one end of the double-threaded lead screw 29 close to the adjustment hole; the adjustment hole includes a large-diameter hole 34 and a small-diameter threaded hole 35 arranged in sequence along the direction close to the reciprocating plate assembly. A threaded post 36 is threadedly fitted in the small-diameter threaded hole 35. A sealing plate 37 is arranged in the large-diameter hole 34. The threaded post 36 is fixedly connected to the sealing plate 37. A sealing gasket 38 is sleeved on the threaded post 36. The sealing gasket 38 is in a compressed state and abuts against the step formed by the large-diameter hole 34 and the small-diameter threaded hole 35. The sealing strength of the adjustment hole is improved through the sealing gasket 38 to avoid the leakage of the oil-water two-phase. A circular protractor is provided on the step. The circular protractor is coaxially arranged with the large-diameter hole 34; the specific adjustment process of the channel slit is as follows: First, move the reciprocating plate assembly to abut against the microchannel housing 7 through the linear motor 6, so that the double-threaded lead screw 29 is coaxially corresponding to the adjustment hole. Then, remove the sealing plate 37, the threaded post 36 and the sealing gasket 38. Insert a hex wrench through the adjustment hole into the internal hexagonal groove 33 of the double-threaded lead screw 29. Then, rotate the double-threaded lead screw 29 by a certain angle corresponding to the size to be adjusted. When the double-threaded lead screw 29 rotates one circle, the side rectangular plate 9 will move a distance of one pitch. One pitch is equally divided into 360 parts. When the double-threaded lead screw 29 rotates 1°, the side rectangular plate 9 will move n / 360, where n is the pitch, so as to have a high movement accuracy. An indicating arrow is sleeved on the hex wrench. The deflection angle of the double-threaded lead screw 29 is judged through the cooperation between the indicating arrow and the circular protractor. Thus, the size of the channel slit in the microchannel housing 7 can be accurately adjusted externally, study the optimal channel slit size of different oil-water two-phases, and use the optimal channel slit size for extraction adaptation, cooperate with active mass transfer enhancement, and further improve the extraction efficiency and extraction effect.

[0038] Example 2: Experiments were carried out using the system of Example 1 above; in the laboratory, according to the ratio of nickel-cobalt-manganese metal ions in the cathode material of the 523-type ternary lithium battery, AR-grade MnSO4·H2O (purchased from Aladdin Chemical Reagent Co., Ltd.) was dissolved in deionized water to obtain an aqueous phase. The organic phase was prepared from an extractant and 260# kerosene in different volume ratios. The mechanism of extraction mass transfer enhancement of the system described in Example 1 was explored under different experimental conditions.

[0039] In this example, the extractant used was 15% D2EHPA (also known as P204). The experiments were carried out under the conditions of an experimental temperature of 25 ± 0.5°C, an operating pressure of atmospheric pressure, and O:A = 1:1.

[0040] In this example, the experimental operation process is as follows:

[0041] Before the experiment starts, first, hot water is passed into the spiral coiled tube 21 through the constant temperature water bath 17 and the peristaltic pump 18. The reciprocating plate assembly is preheated by the temperature of the spiral coiled tube 21 and maintained at the temperature required for the experiment. The temperature is monitored in real time by the high-precision contact thermometer 19 and the temperature sensor 20. After the preheating is completed, the aqueous phase and the organic phase at the experimental temperature are loaded, and then they are pumped into the microchannel housing 7 from two opposite inlets of the T-shaped three-way valve 12 through the aqueous phase injection pump 10 and the organic phase injection pump 11 at a certain injection speed respectively. According to the design principle of the extraction mass transfer enhanced microchannel device: there are mainly two ways to enhance mass transfer: (1) In the static experiment, by using the size effect of the microchannels formed between the inner wall of the side rectangular plate 9 and the microchannel housing 7 and the channel slit between the middle rectangular plate 8 and the side rectangular plate 9, tiny droplets can be formed between the oil and water phases, shortening the mass transfer distance and time, and achieving a large oil-water contact area; (2) In the dynamic experiment, the reciprocating plate assembly is driven by the linear motor 6 to reciprocate. The squeezing effect of the reciprocating motion can promote the mixing of the oil phase and the aqueous phase in the cavity and internal mixing, further increasing the contact area between the oil and water phases in the microchannels. In addition, the reciprocating motion also strengthens the interaction between the oil phase and the aqueous phase and the channel slit wall, which is beneficial to the enhancement of mass transfer. After the extraction mass transfer is enhanced, the oil and water phases flow out through the sampling tube 16. After the fluid flow pattern is stable, the flow states of the oil and water phases at the inlet and outlet of the microchannel housing 7 under different experimental conditions are respectively recorded by the high-speed high-definition imaging system with a 360° light source 24 for further analysis. After the aqueous phase separated by the oil-water separation device 22 is further processed, the concentration of metal ions in the aqueous phase is measured by the atomic absorption spectrometer 23 and then further analyzed; the organic phase separated by the oil-water separation device 22 is characterized by the Fourier transform infrared spectrometer (FTIR) for the change of functional groups and then further analyzed.

[0042] As Figure 6 shown, it is the influence of different injection rates on the extraction efficiency of Mn(II) and the pH of the aqueous phase before and after the experiment, showing the influence of the extraction mass transfer enhanced microchannel device on the extraction efficiency of Mn(II) at different injection rates when the reciprocating plate assembly is stationary. The experimental data show that the extraction efficiency of Mn(II) gradually decreases with the increase of the injection rate, and the extraction efficiencies at different injection rates are between 78.81% and 83.03%. The process of extracting and separating Mn(II) by P204 is a cation exchange process, and the specific chemical reaction is shown in formula (1).

[0043]

[0044] Among them, (HA)2 represents the P204 dimer, and Mn(HA2)2 is the extracted extractant.

[0045] As shown in formula (1), the extraction process of P204 is a process of releasing H+. The higher the extraction efficiency, the more H+ can be released. The change in pH value of the aqueous phase before and after the extraction experiment is usually also a reflection of the extraction efficiency. Figure 6 As shown in the figure, the pH value of the aqueous phase after the experiment showed a gradual upward trend with the increase of injection rate. The pH value of the aqueous phase changed the most at 3 mL / min, and the change of pH value was consistent with the change trend of extraction efficiency.

[0046] In the process of microchannel extraction experiment, the factors that have a greater impact on the extraction and separation efficiency are mainly the residence time and the specific surface area of effective contact between the oil phase and the water phase. Similarly, the extraction mass transfer intensification microchannel device is no exception. When the reciprocating plate assembly is in a stationary state, the driving force of the oil-water phase in the entire device is provided by the injection rate. The relationship between the injection rate and the driving force is positively correlated, while the relationship between the driving force and the residence time is negatively correlated. In the extraction mass transfer intensification microchannel device, the amount of liquid accumulated in the cavity at the inlet increases with the increase of the injection rate in the same time. In the process of increasing the driving force, the effective contact area between the oil phase and the water phase in the channel gap also gradually increases, which is beneficial to the extraction. However, the increase in injection speed will shorten the effective contact time in the channel, which is not conducive to the extraction. According to the results of the reciprocating plate static experiment, the influence of residence time is significantly greater than the influence of effective contact area, and residence time is the main factor affecting the extraction and separation effect.

[0047] In summary, 3 mL / min was selected as the injection rate in the subsequent reciprocating plate dynamics experiments.

[0048] like Figure 7 The figure shows the effect of different reciprocating plate assembly movement rates on the Mn(II) extraction efficiency and the pH value of the aqueous phase before and after the experiment. The effect of the reciprocating plate assembly on the Mn(II) extraction efficiency at different movement rates is discussed. The experimental data show that the reciprocating plate movement enhances the extraction efficiency of Mn(II). The extraction efficiency of Mn(II) at different reciprocating plate movement rates increases from 78.81% to 83.03% to 81.55% to 86.39%. Compared with the injection rate of 3mL / min when the reciprocating plate is static, the extraction efficiency is significantly improved when the reciprocating plate movement rate is between 20 and 60.

[0049] In the microchannel device for enhancing extraction mass transfer, when the injection rate is fixed, the residence time controlled by the injection rate will no longer change. At this time, the movement of the reciprocating plate assembly is the most important factor affecting the extraction efficiency of the entire separation system. The movement process of the reciprocating plate assembly drives and enhances the mixing of oil-water phases and internal mixing in the micron-scale channels and channel slits, generating a circulating flow, reducing the mass transfer distance, and increasing the effective contact area. At the same time, the squeezing effect of the reciprocating plate assembly on the cavity at the inlet position of the microchannel housing 7 further enhances the mixing of oil-water phases and internal mixing. However, it should be noted that the relationship between the enhanced mass transfer effect generated by the movement of the reciprocating plate assembly and the movement rate is not positively correlated. This is mainly because the movement rates of the reciprocating plate assemblies at 80 and 100 are relatively fast, which shortens the residence time of the oil phase and water phase in the channel to a certain extent. Secondly, it may reverse the conditions required for the exchange reaction between the dimer of P204 and metal ions.

[0050] The movement of the reciprocating plate assembly affects the entire extraction system mainly from three aspects: (1) The movement rate of the reciprocating assembly affects the residence time controlled by the injection rate. A higher reciprocating movement rate will shorten the residence time of the oil phase and water phase in the channel; (2) The reciprocating movement enhances the mass transfer in the extraction process; (3) A faster reciprocating movement rate has an inverse effect on the conditions required for the extraction reaction. The change in extraction efficiency is the combined result of the above three factors. When the reciprocating movement rate exceeds 60, the extraction efficiency of Mn(II) decreases significantly, indicating that the reciprocating movement has broken through the critical point for effective mass transfer improvement. Generally speaking, appropriate reciprocating movement has a positive effect on the separation efficiency.

[0051] At the same time, the change results of the pH value also confirm the enhancing effect of the movement of the reciprocating plate assembly on extraction separation. When the reciprocating movement rate is 20, the pH value of the original solution is the lowest, and it is also lower than the pH value of the original solution under the condition of the best extraction efficiency when the reciprocating plate assembly is stationary. As the movement rate of the reciprocating plate assembly increases, the pH value of the extract shows a slow and stable upward trend.

[0052] By comparing the experimental results of different movement states of the reciprocating plate assembly, it fully demonstrates the mass transfer enhancement effect of the microchannel device for enhancing extraction mass transfer.

[0053] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inner", "front", "center", "both ends", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention; and as known to those of ordinary skill in the art, the beneficial effects to be achieved by the present invention are only better beneficial effects compared with the current implementation schemes in the prior art under specific circumstances, rather than directly achieving the best use effects in the industry.

[0054] The above are only the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be changed within the scope of the concept described herein through the above teachings or the techniques or knowledge in related fields. And the changes and alterations made by those skilled in the art that do not depart from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. An active microchannel extraction system for enhancing mass transfer by cavity extrusion extraction, characterized in that, It includes a sample injection device (1), an extraction mass transfer enhanced microchannel device (2), a temperature control and monitoring device (3), a flow pattern monitoring device (4), and a sample data acquisition and measurement device (5). The extraction mass transfer enhanced microchannel device includes a linear motor (6), a microchannel housing (7), and a reciprocating plate assembly. The reciprocating plate assembly is slidably disposed on the inner bottom wall of the microchannel housing (7). The linear motor (6) is disposed on one side of the microchannel housing (7). The output shaft of the linear motor (6) penetrates into the microchannel housing (7) and is connected to the reciprocating plate assembly. The reciprocating plate assembly includes a middle rectangular plate (8) and side rectangular plates (9). The side rectangular plates (9) are disposed on both sides of the middle rectangular plate (8). A micron-level channel is formed between the side rectangular plate (9) and the side wall of the microchannel housing (7). A channel slit is formed between the side rectangular plate (9) and the middle rectangular plate (8). The sample injection device includes an aqueous phase injection pump (10), an organic phase injection pump (11), and a T-shaped three-way valve (12). The aqueous phase injection pump (10) is connected to an input port of the T-shaped three-way valve (12) through an aqueous phase injection pipe (13). The organic phase injection pump (11) is connected to another input port of the T-shaped three-way valve (12) through an organic phase injection pipe (14). The output port of the T-shaped three-way valve (12) is connected to the top of one end of the microchannel housing (7) through an injection pipe (15). The bottom of the other end of the microchannel housing (7) is connected to a sample output pipe (16). The sample output pipe (16) is connected to the sample data acquisition and measurement device. The flow pattern monitoring device (4) is used to record the flow states of the oil-water two-phase flowing into and out of the microchannel housing (7) under different experimental conditions. The temperature control and monitoring device is connected to the microchannel housing (7), and is used to adjust the extraction temperature in the microchannel housing (7).

2. The active microchannel extraction system for enhancing mass transfer by cavity extrusion extraction according to claim 1, wherein The temperature control and monitoring device includes a constant temperature water bath (17), a peristaltic pump (18), a high-precision contact thermometer (19), and a temperature sensor (20). The water outlet of the constant temperature water bath (17) is connected to the input port of the peristaltic pump (18). The output port of the peristaltic pump (18) is connected to a spiral coil (21). The spiral coil (21) is sleeved on the microchannel housing (7). The temperature sensor (20) is disposed in the microchannel housing (7). The output wire of the temperature sensor (20) penetrates out of the microchannel housing (7) and is connected to the high-precision contact thermometer (19).

3. The active microchannel extraction system for enhancing mass transfer by cavity extrusion extraction according to claim 1, characterized in that The sample data acquisition and measurement device includes an oil-water separation device (22) and an atomic absorption spectrometer (23). The sample output pipe (16) is connected to the oil-water separation device (22). The water phase outlet of the oil-water separation device (22) is connected to the atomic absorption spectrometer (23).

4. The active microchannel extraction system for enhanced mass transfer by cavity extrusion extraction according to claim 1, wherein There are two sets of the flow pattern monitoring devices, which are respectively arranged at the sample inlet pipe (15) and the sample outlet pipe (16). The flow pattern monitoring device includes a 360° light source (24) and a high-speed high-definition imaging camera (25), and the 360° light source (24) is arranged on one side of the high-speed high-definition imaging camera (25).

5. The active microchannel extraction system for enhancing mass transfer by cavity extrusion extraction according to claim 1, wherein Rectangular protrusions (26) are fixed on both sides of the middle rectangular plate (8). A rectangular groove (27) is formed on one side of the side rectangular plate (9) close to the middle rectangular plate (8). The rectangular protrusion (26) is arranged in the rectangular groove (27), and a channel slit is formed between the rectangular protrusion (26) and the rectangular groove (27). The side rectangular plate (9) has the freedom to move away from or close to the middle rectangular plate (8) to change the size of the channel slit.

6. The active microchannel extraction system for enhanced mass transfer in cavity extrusion extraction according to claim 5, wherein Elastic sealing gaskets (28) are fixed on both sides of the middle rectangular plate (8) at the positions of the rectangular protrusions (26), and the elastic sealing gaskets (28) are in a compressed state and in contact with the side rectangular plate (9).

7. The active microchannel extraction system for enhancing mass transfer by cavity extrusion extraction according to claim 6, characterized in that, The extraction mass transfer intensification microchannel device further includes a bidirectional threaded lead screw (29) and a bushing (30). The bushing (30) is rotatably sleeved in the middle of the bidirectional threaded lead screw (29), and the bushing (30) is fixedly penetrated in the middle rectangular plate (8). The two side rectangular plates (9) are respectively threadedly sleeved on two threaded segments with opposite rotations of the bidirectional threaded lead screw (29).

8. An active microchannel extraction system for enhancing mass transfer by cavity extrusion extraction, according to claim 7, characterized in that, A limiting protrusion (31) is fixed on the inner bottom wall of the microchannel housing (7). A limiting groove (32) is formed at the bottom of the middle rectangular plate (8). The limiting protrusion (31) is fitted in the limiting groove (32), and the bottom wall of the side rectangular plate (9) is in close contact with the inner bottom wall of the microchannel housing (7).

9. The active microchannel extraction system for enhancing mass transfer by cavity extrusion extraction according to claim 8, characterized in that An adjustment hole is formed on the side wall of the microchannel housing (7). When one end of the reciprocating plate assembly abuts against the microchannel housing (7), the adjustment hole corresponds to one end of the bidirectional threaded lead screw (29). An internal hexagonal groove (33) is formed at one end of the bidirectional threaded lead screw (29) close to the adjustment hole; The adjustment hole includes a large-diameter hole (34) and a small-diameter threaded hole (35) arranged in sequence along the direction close to the reciprocating plate assembly. A threaded post (36) is threadedly fitted in the small-diameter threaded hole (35). A sealing disc (37) is arranged in the large-diameter hole (34). The threaded post (36) is fixedly connected to the sealing disc (37). A sealing gasket (38) is sleeved on the threaded post (36), and the sealing gasket (38) is in a compressed state and abuts against the step formed by the large-diameter hole (34) and the small-diameter threaded hole (35).

10. The active microchannel extraction system for enhancing mass transfer by cavity extrusion extraction according to claim 9, wherein, A circular angle scale is arranged on the step, and the circular angle scale is coaxially arranged with the large-diameter hole (34).

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