Online intelligent monitoring system and method for micro-plastics in water environment

Abstract

According to the system, a filter membrane group is arranged in a pretreatment chamber, an inlet of the filter membrane group is connected with an automatic sampling head, an inlet of a separation chamber is connected with an outlet of the pretreatment chamber, a filling port of the separation chamber is connected with an outlet of a sodium chloride solution chamber, and an electronic valve is arranged at the outlet; the inlet of the enrichment chamber is connected with the overflow port of the separation chamber, and a microporous filter membrane is arranged in the enrichment chamber; an overflow pipeline of the enrichment chamber extends into the detection chamber; the three-dimensional motion platform is arranged in the detection chamber, and the detection platform is mounted on the three-dimensional motion platform; and the Raman probe is arranged in the detection cavity and is respectively connected with the laser and the Raman spectrometer. The method comprises the following steps: collecting a water sample, carrying out multi-stage filtration in the pretreatment chamber, carrying out density flotation in the separation chamber, concentrating in the enrichment chamber, enriching in the detection platform, carrying out laser irradiation, and synchronously collecting Raman spectrum signals for analysis. The system and the method can realize qualitative analysis of the micro-plastics in the water environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of intelligent monitoring, and specifically relates to an online intelligent monitoring system and method for microplastics in water environment. Background Art

[0002] Microplastics refer to plastic particles with a diameter less than 5 millimeters. With the aggravation of the global plastic pollution problem, microplastics have gradually become an important part of water pollution. Microplastics widely exist in various water bodies around the world, including oceans, lakes, rivers, and groundwater, etc. Due to the small size and high persistence of microplastics, they can exist in the water environment for a long time and enter the ecosystem through the biological ingestion pathway, thus affecting the growth, reproduction, and even survival of aquatic organisms. More importantly, microplastics can adsorb harmful chemical substances in water, such as heavy metals, persistent organic pollutants, etc. The attachment of these substances not only makes the microplastics themselves toxic, but also may be continuously transmitted through the food chain, ultimately affecting human health. With the in-depth research, the health risk problem of microplastics has become more apparent, especially the possible microplastic pollution in drinking water, which poses an extremely severe challenge to public health. Therefore, developing an efficient, sensitive, and automated intelligent detection technology for microplastics in water is an important requirement for water environmental protection and public health safety.

[0003] Currently, the detection methods of microplastics mainly rely on several traditional technologies, including microscopic analysis, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, pyrolysis-gas chromatography-mass spectrometry (Py-GC / MS), etc. Microscopic analysis is the most intuitive method, which requires manually observing the microplastic particles in the sample, but this method has low efficiency and is easily affected by human factors, making it difficult to achieve high-throughput detection. FTIR and Raman spectroscopy have strong advantages in providing chemical information on the composition of microplastics, especially playing an important role in the qualitative analysis of microplastics. However, the traditional Raman and FTIR methods have poor sensitivity in the case of low microplastic concentration, and the operation is complex, unable to meet the requirements of rapid on-site detection. Pyrolysis-gas chromatography-mass spectrometry (Py-GC / MS) can achieve quantitative analysis of microplastics, but due to its cumbersome operation, expensive equipment, and complex sample processing, it is suitable for laboratory environment rather than large-scale on-site monitoring. Although some emerging technologies (such as spectral analysis, microfluidic chips, etc.) have made certain progress in recent years, due to the detection efficiency, equipment cost, and complex operation process, it is still difficult to meet the actual needs of rapid, accurate, and efficient detection of microplastics in water. Therefore, developing a new detection technology integrating high sensitivity, low cost, rapid analysis, and automated detection functions has become an urgent task in the current prevention and control of microplastic pollution. Summary of the Invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides an online intelligent monitoring system and method for microplastics in water environment. The system can conveniently and efficiently implement the detection operation of microplastic particles in the water environment, has high detection accuracy, and can provide reliable technical support for the treatment of microplastic pollution in the water environment. The implementation process of the method is simple and has a high degree of intelligence. It integrates functions of high sensitivity, low cost, rapid analysis and automatic detection, and can realize the qualitative analysis of microplastics in the water environment.

[0005] To achieve the above object, the present invention provides an online intelligent monitoring system for microplastics in water environment, including a sampling and pretreatment unit, a microplastic detection and analysis unit, and an enrichment and concentration unit;

[0006] The sampling and pretreatment unit includes a pretreatment chamber, an automatic sampling head, a flow sensor, an environmental sensor, a filter membrane group, a separation chamber, an electronic valve, a transverse partition, a partition driving mechanism, a sodium chloride solution chamber, and a first liquid pump; a chamber inlet A and a chamber outlet A are respectively opened at the top and bottom of the pretreatment chamber, and a sampling pipeline is connected to the chamber inlet A; the automatic sampling head is installed at the inlet end of the sampling pipeline; the flow sensor is installed at the sample inlet of the automatic sampling head; the environmental sensor is installed in the inner cavity of the automatic sampling head; the filter membrane group is horizontally installed in the middle section inside the pretreatment chamber, and the filter membrane group is composed of multiple hierarchical filter membranes distributed from top to bottom in sequence, and the filter holes of the multiple hierarchical filter membranes gradually decrease from top to bottom; the separation chamber is located below the pretreatment chamber, and a chamber inlet B and a chamber outlet B are respectively opened at its top and bottom, a filling port is opened at the bottom of one side thereof, an overflow port A is opened at the upper part of one side thereof, and the chamber inlet B is connected to the chamber outlet A through a communication pipeline, the chamber outlet B is connected to a drain pipeline A, the filling port is connected to a filling pipeline, the overflow port A is connected to an overflow pipeline A, and a partition chute is horizontally opened at the right side of the lower part of the separation chamber; the electronic valve is installed in the chamber outlet B; the transverse partition is slidably inserted into the partition chute and divides the separation chamber into an upper chamber and a lower chamber after completely sliding into the separation chamber; the partition driving mechanism is installed outside the separation chamber, and its output end is connected to the right end of the transverse partition for driving the transverse partition to reciprocate horizontally; the sodium chloride solution chamber is located on one side outside the separation chamber, a drain port is opened at its bottom, and the drain port is connected to the inlet end of the filling pipeline; the first liquid pump is connected in series on the filling pipeline;

[0007] The microplastic detection and analysis unit includes a detection chamber, a laser, a Raman spectrometer, a three-dimensional motion platform, a detection platform, and a Raman probe; the detection chamber is arranged on the right side of the separation chamber, with a detection area provided on the left side inside it, a detection channel communicating with the detection area opened on its left side, and a probe mounting hole opened in the central area of the detection area on its upper side; both the laser and the Raman spectrometer are arranged outside the detection chamber; the three-dimensional motion platform is installed on the bottom side inside the detection chamber; the detection platform is fixedly installed on the support table of the three-dimensional motion platform; the Raman probe is fixedly inserted into the probe mounting hole and connected to the laser through a laser emission optical fiber, and at the same time, connected to the Raman spectrometer through a laser reception optical fiber;

[0008] The enrichment and concentration unit includes an enrichment chamber, a microporous filter membrane, a second liquid pump, a third liquid pump, and a fourth liquid pump; the enrichment chamber is located between the separation chamber and the detection chamber, with a chamber inlet C and a chamber outlet C opened at the top and bottom respectively, an overflow port B opened at the upper part of one side, and the chamber inlet C connected to the liquid outlet end of the overflow pipeline A, the chamber outlet C connected to a drain pipeline B, the overflow port B connected to an overflow pipeline B, and the outlet end of the overflow pipeline B extending to the left side of the detection area through the detection channel and connected to a liquid outlet elbow; the microporous filter membrane is horizontally installed inside the enrichment chamber and is located at the lower edge of the overflow port B; the second liquid pump is connected in series on the overflow pipeline A; the third liquid pump is connected in series on the drain pipeline B; the fourth liquid pump is connected in series on the overflow pipeline B.

[0009] Furthermore, in order to enable the system to have an automatic cleaning function to ensure the detection accuracy and stability during long-term continuous operation, the microplastic detection and analysis unit further includes a vertical partition board, a motion connecting rod, a cleaning mechanism, and a cleaning driving mechanism; a cleaning area is provided on the right side inside the detection chamber, and a cleaning channel communicating with the cleaning area is opened on its right side; the vertical partition board is fixedly installed in the upper space inside the detection chamber, and the detection area and the cleaning area are respectively formed in the left space and the right space of the vertical partition board; a set distance is left between the lower edge of the vertical partition board and the bottom plate of the detection chamber to form a horizontal passage; a horizontal sliding track is installed on the bottom plate inside the detection chamber; the three-dimensional motion platform is installed on the horizontal sliding track; the motion connecting rod is rotatably installed in the cleaning channel; the cleaning mechanism is located in the cleaning area and is fixedly installed at the left end of the motion connecting rod; the cleaning driving mechanism is arranged outside the detection chamber, and its output end is connected to the right end of the motion connecting rod.

[0010] Furthermore, in order to effectively reduce the interference of fluorescence on the detection result and improve the quality of the Raman signal, the detection platform is made of a material with a low fluorescence background, and a superhydrophobic SERS substrate is coated at the central position of its upper surface, and a heating plate is arranged inside it.

[0011] Further, in order to facilitate the implementation of fully automated detection operations, it further includes a control unit, and the control unit is respectively connected to a flow sensor, an environmental sensor, an automatic sampling head, an electronic valve, a partition driving mechanism, a first liquid pump, a laser, a Raman spectrometer, a three-dimensional motion platform, a second liquid pump, a third liquid pump, a fourth liquid pump, a cleaning driving mechanism, and a heating plate.

[0012] Further, in order to reduce the adhesion of microplastic particles and improve the recovery rate of microplastic particles, the inner surface of the enrichment chamber is coated with a superhydrophobic coating; in order to enhance the filtration effect, the microporous filter membrane is made of a nano-enhanced composite membrane.

[0013] Further, in order to improve the stability of the laminar flow, reduce the particle deposition, and thus significantly improve the enrichment efficiency of microplastics, a flow guide plate is provided at the chamber inlet C of the enrichment chamber.

[0014] As a preference, the control unit is a PLC controller.

[0015] In the present invention, by installing a flow sensor at the sample inlet of the automatic sampling head, it is convenient to collect the flow signal of the water sample in real time during the sampling process, and then the flow data can be obtained based on the flow signal. Further, it can be determined in real time whether the amount of the incoming sample has met the required detection requirements. When the sample amount has met the detection requirements, the automatic sampling head can be directly controlled to stop working. By arranging an environmental sensor inside the automatic sampling head, it is convenient to collect the temperature signal and pH value data of the water sample in real time during the sampling process. The filter membrane group is composed of multiple hierarchical filter membranes spaced from top to bottom in sequence, which can form a hierarchical filtration structure. In this way, when the water sample passes through the filter membrane group, large particle pollutants and non-target plastic particles can be efficiently filtered out step by step, and only the target microplastic particles are retained. A saturated sodium chloride solution is filled in the sodium chloride solution chamber. At the same time, it is connected to the filling port at the bottom of the separation chamber through a filling pipeline with a first liquid pump in series, which is convenient to suck the saturated sodium chloride solution by the first liquid pump and quantitatively inject it into the interior of the separation chamber, so as to form a density flotation environment with the saturated sodium chloride solution, which is conducive to promoting the flotation and density separation process of microplastic particles. In this way, when the water sample enters through chamber inlet B, it is convenient to quickly and effectively separate the microplastic particles in the water sample from other particles by the density flotation method, so that the microplastic particles can be guided to enrich in the upper layer area, while the heavier particles precipitate to the bottom. On this basis, a horizontal chute is arranged in the separation chamber, and a horizontal partition is driven to slide in the horizontal chute by a partition driving mechanism, which is convenient to divide the separation chamber into an upper chamber and a lower chamber. In this way, the target microplastic particles can be retained in the water sample in the upper chamber, and the preliminary screening of the water sample is realized. By connecting an overflow pipeline A with a second liquid pump in series through an overflow hole A at the upper part of the separation chamber, it is convenient to transport the water sample after density separation to the enrichment chamber by the second liquid pump for subsequent concentration operation. The microporous filter membrane is arranged at the lower edge of the overflow hole B, which is convenient to ensure that the high-concentration microplastic suspension obtained after separation and filtration can smoothly pass through the overflow pipeline B and the fourth liquid pump and enter the detection chamber for subsequent detection process. A drain pipeline B with a third liquid pump in series is connected to the chamber outlet C at the bottom of the enrichment chamber, which is convenient to provide negative pressure by the third liquid pump. Due to the large resistance of the microporous filter membrane, the filtration efficiency can be significantly improved by providing negative pressure, and it can ensure that the water sample can smoothly flow to the microporous filter membrane, thereby shortening the concentration filtration time. The outlet end of the overflow pipeline B with a fourth liquid pump in series extends into the detection area inside the detection chamber and is connected with a liquid outlet elbow, which is convenient to extract the high-concentration microplastic suspension and quantitatively drop it onto the detection platform, thus facilitating the subsequent detection of microplastic particles by a Raman probe. The detection platform is installed on a three-dimensional motion platform located in the detection chamber, which is convenient to conveniently and accurately change the position of the detection platform in the X direction, Y direction and Z direction by the three-dimensional motion platform.By coating a superhydrophobic SERS substrate at the center position of the upper surface of the detection platform, the superhydrophobic SERS substrate can be used to greatly enhance the Raman spectral signal generated when microplastic particles are irradiated by laser, which is beneficial to improving the detection accuracy. By arranging a heating plate inside the detection platform, it is convenient to promote the rapid evaporation of water in the sample by heating, and enable the microplastic particles to be enriched in the central area of the superhydrophobic SERS substrate, so as to further ensure the sensitivity and signal-to-noise ratio of SERS spectral signal detection. Connect the Raman probe to the laser through the laser emission optical fiber and to the Raman spectrometer through the laser receiving optical fiber, which can not only conveniently receive the laser emitted by the laser and irradiate the microplastic particles at the enrichment point, but also synchronously collect the generated Raman scattering spectral signal and transmit it to the Raman spectrometer.

[0016] Compared with the traditional method, this system uses a flow sensor to dynamically adjust the injection volume, ensuring the representativeness of the water sample. At the same time, it uses the density gradient flotation technology, combines with the transverse baffle to dynamically adjust the separation area, and effectively enriches microplastics by using a microporous filter membrane, reducing impurity interference and improving the separation purity. At the same time, based on the superhydrophobic SERS technology on the detection platform, the droplet condensation effect is used to highly enrich microplastic particles, which can significantly enhance the Raman spectral signal, making the detection sensitivity significantly enhanced, and can support the long-term environmental monitoring and pollution warning requirements. This system can conveniently and efficiently realize the detection operation of microplastic particles in the water environment, with high detection accuracy, and can provide reliable technical support for the treatment of microplastic pollution in the water environment.

[0017] The present invention also provides a method for on-line intelligent monitoring of microplastics in water environment, using an on-line intelligent monitoring system for microplastics in water environment, including the following steps;

[0018] Step 1: Fill the sodium chloride solution chamber with saturated sodium chloride solution, and then place the on-line intelligent monitoring system for microplastics in water environment near the water environment to be detected;

[0019] Step 2: Control the first liquid pump to start working through the control unit, and use the first liquid pump to inject the saturated sodium chloride solution into the separation chamber until the set capacity is reached, and then stop the first liquid pump;

[0020] Step 3: Insert the automatic sampling head into the water environment, and control the automatic sampling head to start working through the control unit. Transport the water sample to the pretreatment chamber through the sampling pipeline. Meanwhile, use the flow sensor to collect the flow signal of the sample in real time, use the environmental sensor to collect the physical and chemical signals of the sample in real time, and send the flow signal, physical and chemical signals to the control unit in real time. The control unit obtains the flow data of the sample according to the flow signal, and obtains the temperature data and pH value data of the sample according to the physical and chemical signals. When the flow quantity of the sample reaches the set flow sampling threshold, control the automatic sampling head to stop the sampling operation;

[0021] Step 4: In the pretreatment chamber, use multiple hierarchical filter membranes in the filter membrane group to filter the water sample step by step, filter out non-target pollutants and large-particle-size particles, and only retain particles below the target size in the water sample. Then use the connecting pipeline to divert the filtered water sample to the separation chamber;

[0022] Step 5: In the separation chamber, use the pre-injected saturated sodium chloride solution to quickly and effectively separate microplastics from other particles in the water sample by density flotation method. After the separation is completed, the lighter microplastic particles are enriched in the upper region of the liquid, and the heavier particles settle in the lower region of the liquid. Control the partition driving mechanism to start working, and drive the horizontal partition to slowly move to the left in the horizontal direction until the separation chamber is divided into an upper chamber and a lower chamber;

[0023] Step 6: Control the second liquid pump to start working, transport the water sample in the upper chamber to the enrichment chamber. Meanwhile, control the third liquid pump to start working to provide negative pressure for the filtration of the water sample, and use the microporous filter membrane to separate and filter the microplastics to obtain a high-concentration microplastic suspension;

[0024] Step 7: First, control the three-dimensional motion platform to move in the X direction until it moves to the left end of the horizontal sliding track. Then control the three-dimensional motion platform to move in the Y direction and Z direction until the detection platform is at a set distance directly below the liquid outlet elbow. Then control the fourth liquid pump to start working, transport the high-concentration microplastic suspension above the microporous filter membrane to the detection chamber, and drip it onto the superhydrophobic SERS substrate on the detection platform through the liquid outlet elbow;

[0025] Step 8: First, control the heating plate in the detection platform to start working, heat the microplastic suspension on the superhydrophobic SERS substrate to promote the evaporation of the liquid. During the evaporation process, use the condensation effect of the superhydrophobic SERS substrate to make the microplastic particles gather towards the central minimum contact area, and form a high-concentration enrichment point at the center of the superhydrophobic SERS substrate. Then control the three-dimensional motion platform to move in the X direction, Y direction and Z direction until the detection platform moves to a set distance directly below the Raman probe;

[0026] Step Nine: Control the laser to start working, emit irradiation laser to the microplastic particles at the high-concentration enrichment point through the laser emission optical fiber. At the same time, use the superhydrophobic SERS substrate to enhance the Raman scattering spectral signal generated on the surface of the microplastic particles to form a SERS Raman scattering spectral signal. At the same time, receive the SERS Raman scattering spectral signal through the laser receiving optical fiber and transmit it to the Raman spectrometer;

[0027] The Raman spectrometer obtains SERS Raman spectral data based on the SERS Raman scattering spectral signal, and uses a background subtraction algorithm to remove the interference signals of the solvent and the substrate. At the same time, uses noise filtering to optimize the spectral quality, and automatically matches the spectral features through principal component analysis and machine learning algorithms, and then compares with the massive sample data in the microplastic database to determine the type of microplastic. At the same time, calibrate the spectral curve in combination with the intensity of the SERS Raman scattering spectral signal, and calculate the concentration of the microplastic using the integral area of the Raman peak.

[0028] Furthermore, in order to be able to perform cleaning operations on the detection platform so as to enable continuous long-term detection operations, in Step Eight, after completing the Raman spectroscopy detection operation of the microplastic, first control the three-dimensional motion platform to move in the X direction until it moves to the right end of the transverse sliding track through the transverse passage, and then control the three-dimensional motion platform to move in the Y direction and the Z direction until the detection platform moves directly below the cleaning mechanism and contacts the cleaning mechanism; then control the cleaning drive mechanism to start working to drive the cleaning mechanism to perform a rotating action through the motion connecting rod to clean the upper surface of the detection platform.

[0029] As a preference, in Step Four, when it is necessary to discharge the heavy particles and impurities deposited at the bottom of the separation chamber, first control the partition drive mechanism to start working, drive the transverse partition to move slowly in the horizontal direction until the separation chamber is divided into an upper chamber and a lower chamber, and then control the electronic valve to open the chamber outlet B to discharge the heavy particles and impurities at the bottom through the drain pipe A. After the discharge is completed, close the electronic valve. Then, control the first liquid pump to start working for a set time, and use the first liquid pump to add saturated sodium chloride solution to the separation chamber until it reaches the set capacity, and then stop the first liquid pump.

[0030] In view of the limitations of existing microplastic detection technologies, the present invention provides an automated intelligent detection method for microplastics in water environments based on membrane filtration, superhydrophobic enrichment, and surface-enhanced Raman spectroscopy (SERS) technology. Specifically, during the sampling process, the feedback signal of a flow sensor can be used to dynamically adjust the sample injection volume, which is conducive to achieving quantitative sampling. A hierarchical filtration structure is formed by multiple hierarchical filter membranes to filter the water sample, and large particle pollutants and non-target plastic particles can be efficiently filtered out step by step, leaving only target microplastic particles. First, a certain amount of saturated sodium chloride solution is injected into the separation chamber, and then the filtered sample is diverted into the separation chamber. The density gradient flotation technology can be used to enrich the microplastics in the upper region of the liquid. By combining the lateral partition to dynamically adjust the separation region, a water sample containing microplastic particles can be obtained based on density separation. Then, the microfiltration membrane filtration technology is adopted in the enrichment chamber to achieve preliminary enrichment of microplastics. Then, the highly concentrated microplastic suspension after preliminary enrichment is dropped onto the detection platform, and the microplastic particles are further concentrated through a superhydrophobic surface. At the same time, the evaporation of water is assisted by heating to obtain a highly concentrated enrichment point, significantly enhancing the detection sensitivity. By combining SERS technology, this method can detect microplastics with high sensitivity under low-concentration conditions while retaining their chemical fingerprint information.

[0031] This method integrates automatic sampling, density gradient separation, dynamic adjustment of the separation region by a lateral partition, enrichment and concentration, superhydrophobic SERS detection, and intelligent analysis of detection data. It can realize the full-process automated detection process of microplastic particles in the water environment, and the entire detection process can be carried out without manual intervention, reducing manual operation and analysis errors, improving detection efficiency and long-term stability, and meeting the requirements for rapid, accurate, and efficient detection of microplastics in the water environment. The implementation process of this method is simple and highly intelligent, and it can provide efficient and convenient technical support for environmental monitoring, drinking water safety assessment, and microplastic pollution control. Description of the Drawings

[0032] Figure 1 is a schematic structural diagram of the present invention;

[0033] Figure 2 is a schematic block diagram of the control part in the present invention.

[0034] In the figure: 1. Automatic sampling head; 2. Environmental sensor; 3. Pretreatment chamber; 4. Filter membrane; 5. Separation chamber; 6. Horizontal partition; 7. Partition driving mechanism; 8. Electronic valve; 9. Sodium chloride solution chamber; 10. First liquid pump; 11. Second liquid pump; 12. Enrichment chamber; 13. Third liquid pump; 14. Microfiltration membrane; 15. Fourth liquid pump; 16. Detection platform; 17. Three-dimensional motion platform; 18. Raman probe; 19. Laser emission optical fiber; 20. Laser; 21. Detection chamber; 22. Motion connecting rod; 23. Cleaning driving mechanism; 24. Cleaning mechanism; 25. Laser receiving optical fiber; 26. Raman spectrometer; 27. Sampling pipeline; 28. Connecting pipeline; 29. Drainage pipeline A; 30. Filling pipeline; 31. Overflow pipeline A; 32. Drainage pipeline B; 33. Overflow pipeline B; 34. Vertical partition; 35. Flow sensor; 36. Detection area; 37. Cleaning area; 38. Horizontal passage; 39. Liquid outlet elbow. Detailed implementation mode

[0035] The present invention will be further described below in conjunction with the accompanying drawings.

[0036] As Figure 1 and Figure 2 shown, the present invention provides an online intelligent monitoring system for microplastics in water environment, including a sampling and pretreatment unit, a microplastic detection and analysis unit, and an enrichment and concentration unit;

[0037] The sampling and preprocessing unit includes a preprocessing chamber 3, an automatic sampling head 1, a flow sensor 35, an environmental sensor 2, a filter membrane group 4, a separation chamber 5, an electronic valve 8, a transverse partition 6, a partition driving mechanism 7, a sodium chloride solution chamber 9, and a first liquid pump 10; a chamber inlet A and a chamber outlet A are respectively opened at the top and bottom of the preprocessing chamber 3, and a sampling pipeline 27 is connected to the chamber inlet A; the automatic sampling head 1 is installed at the inlet end of the sampling pipeline 27; as a preference, the automatic sampling head 1 also has an automatic timer, so that after being started, it can start working according to the set time interval to realize the function of regular sampling; the flow sensor 35 is installed at the sample inlet of the automatic sampling head 1; the environmental sensor 2 is installed in the inner cavity of the automatic sampling head 1, as a preference, a temperature sensor and a pH value sensor are arranged inside the environmental sensor 2, the temperature sensor is used for collecting the temperature signal of the water sample in real time, and the pH value sensor is used for collecting the pH data of the water body in real time; the filter membrane group 4 is horizontally installed in the middle section inside the preprocessing chamber 3, the filter membrane group 4 is composed of multiple hierarchical filter membranes distributed from top to bottom in sequence, and the filter holes of the multiple hierarchical filter membranes gradually decrease from top to bottom; as a preference, the multiple hierarchical filter membranes adopt a combination of hydrophilic filter membranes and hydrophobic filter membranes, wherein the hydrophilic filter membranes are used for removing organic matters and suspended matters, and the hydrophobic filter membranes are used for removing oily pollutants, and at the same time, hydrophobic microplastic particles are retained.

[0038] The separation chamber 5 is located below the preprocessing chamber 3, a chamber inlet B and a chamber outlet B are respectively opened at the top and bottom of the separation chamber 5, a filling port is opened at the bottom of one side of the separation chamber 5, an overflow port A is opened at the upper part of one side of the separation chamber 5, the chamber inlet B is connected to the chamber outlet A through a communication pipeline 28, the chamber outlet B is connected to a drain pipeline A 29, the filling port is connected to a filling pipeline 30, the overflow port A is connected to an overflow pipeline A 31, and a partition sliding groove is horizontally opened on the right side of the lower part of the separation chamber 5; the electronic valve 8 is installed in the chamber outlet B; the transverse partition 6 is slidably inserted into the partition sliding groove and divides the separation chamber 5 into an upper chamber and a lower chamber after completely sliding into the separation chamber 5, wherein a communication port communicating with the outside is opened at the right end of the partition sliding groove at the right end of the separation chamber 5, and in order to ensure the sealing effect, the connection port and the partition sliding groove are in sliding sealing fit, so that when the transverse partition 6 slides outward from the communication port at the right end of the partition sliding groove, internal liquid can be prevented from overflowing to the outside through the communication port; the partition driving mechanism 7 is installed outside the separation chamber 5, and its output end is connected to the right end of the transverse partition 6 and is used for driving the transverse partition 6 to move reciprocally in the horizontal direction, as a preference, the partition driving mechanism 7 can adopt a linear electric push rod motor; the sodium chloride solution chamber 9 is located on one side outside the separation chamber 5, a drain port is opened at the bottom of the sodium chloride solution chamber 9, and the drain port is connected to the liquid inlet end of the filling pipeline 30; the first liquid pump 10 is connected in series on the filling pipeline 30.

[0039] As an option, a throttle orifice can be provided in the connecting pipeline 28, thereby achieving the effect of buffering the flow, preventing violent fluctuations of the water sample, ensuring that the microplastic particles can be more evenly distributed in the water sample, and thus being beneficial to improving the subsequent filtration effect and efficiency.

[0040] The microplastic detection and analysis unit includes a detection chamber 21, a laser 20, a Raman spectrometer 26, a three-dimensional motion platform 17, a detection platform 16, and a Raman probe 18; the detection chamber 21 is arranged on the right side of the separation chamber 5, a detection area 36 is provided on the left side inside it, a detection channel communicating with the detection area 36 is opened on its left side, and a probe mounting hole is opened in the central area of the detection area 36 on its upper side; both the laser 20 and the Raman spectrometer 26 are arranged outside the detection chamber 21; the three-dimensional motion platform 17 is installed on the bottom side inside the detection chamber 21, and is driven by a high-precision precision stepping motor inside to provide XYZ three-dimensional precise positioning function; the detection platform 16 is fixedly installed on the support platform of the three-dimensional motion platform 17; the Raman probe 18 is fixedly inserted into the probe mounting hole and is connected to the laser 20 through a laser emission optical fiber 19, and at the same time, is connected to the Raman spectrometer 26 through a laser reception optical fiber 25;

[0041] The enrichment and concentration unit includes an enrichment chamber 12, a microporous filter membrane 14, a second liquid pump 11, a third liquid pump 13, and a fourth liquid pump 15; the enrichment chamber 12 is located between the separation chamber 5 and the detection chamber 21, a chamber inlet C and a chamber outlet C are respectively opened at the top and bottom of it, an overflow port B is opened at the upper part of one side of it, and the chamber inlet C is connected to the liquid outlet end of the overflow pipeline A31, the chamber outlet C is connected to a drain pipeline B32, the overflow port B is connected to an overflow pipeline B33, and the outlet end of the overflow pipeline B33 extends to the left side of the detection area 36 through the detection channel and is connected to a liquid outlet elbow 39, wherein the liquid outlet end of the liquid outlet elbow 39 is located at the lower end; the microporous filter membrane 14 is horizontally installed inside the enrichment chamber 12 and is located at the lower edge of the overflow port B for further solid-liquid separation to intercept the microplastic particles in the chamber, while allowing the clear liquid to pass through the microporous filter membrane 14 and be discharged through the drain pipeline B32; the second liquid pump 11 is connected in series on the overflow pipeline A31; the third liquid pump 13 is connected in series on the drain pipeline B32; the fourth liquid pump 15 is connected in series on the overflow pipeline B33.

[0042] In order to enable the system to have an automatic cleaning function to ensure the detection accuracy and stability during long-term continuous operation, the microplastic detection and analysis unit further includes a vertical partition 34, a motion connecting rod 22, a cleaning mechanism 24 and a cleaning drive mechanism 23; a cleaning area 37 is provided on the right side inside the detection chamber 21, and a cleaning channel communicating with the cleaning area 37 is opened on its right side; the vertical partition 34 is fixedly installed in the upper space inside the detection chamber 21, and the detection area 36 and the cleaning area 37 are respectively formed in the left space and the right space of the vertical partition 34; a set distance is left between the lower end edge of the vertical partition 34 and the bottom plate of the detection chamber 21 to form a horizontal passage 38; a horizontal sliding track is installed on the bottom plate inside the detection chamber 21; the three-dimensional motion platform 17 is installed on the horizontal sliding track;

[0043] The motion connecting rod 22 is rotatably installed in the cleaning channel; the cleaning mechanism 24 is located in the cleaning area 37 and is fixedly installed at the left end of the motion connecting rod 22; the cleaning drive mechanism 23 is arranged outside the detection chamber 21, and its output end is connected to the right end of the motion connecting rod 22. The cleaning drive mechanism 23 is used to drive the motion connecting rod 22 to perform a rotational action, and at the same time, is used to drive the motion connecting rod 22 to move horizontally. As a preference, the cleaning drive mechanism 23 can be composed of a rotary drive motor and a horizontal pushing device. Among them, the rotary drive motor is used to drive the motion connecting rod 22 to perform a rotational action, and the horizontal pushing device is supported at the bottom of the rotary drive motor and is used to drive the rotary drive motor horizontally. Among them, the horizontal pushing device is preferably composed of a linear electric push rod motor and a support frame installed at the telescopic end of the linear electric push rod motor, and the rotary drive motor is installed on the top of the support frame;

[0044] In order to effectively reduce the interference of fluorescence on the detection results and improve the quality of Raman signals, the detection platform 16 is made of a low-fluorescence background material, and a superhydrophobic SERS substrate is coated at the center position of its upper surface, and a heating plate is arranged inside it. As a further preference, the upper surface of the detection platform 16 is a high-precision flat structure, and its surface can carry the microplastic samples that have been enriched and concentrated, and can ensure that the samples are evenly distributed on it;

[0045] In order to facilitate the realization of fully automated detection operations, a control unit is further included. The control unit is respectively connected to a flow sensor 35, an environment sensor 2, an automatic sampling head 1, an electronic valve 8, a partition drive mechanism 7, a first liquid pump 10, a laser 20, a Raman spectrometer 26, a three-dimensional motion platform 17, a second liquid pump 11, a third liquid pump 13, a fourth liquid pump 15, a cleaning drive mechanism 23 and a heating plate.

[0046] As a preference, it further includes a power supply module and a communication module. The power supply module is connected to the control unit and is used for power supply. The communication module is connected to the control unit and is used for establishing a communication connection between the monitoring system and external devices;

[0047] As a preference, it further includes a data storage module. The data storage module is connected to the control unit and is used for building a plastic database.

[0048] To reduce the adhesion of microplastic particles and improve the recovery rate of microplastic particles, the inner surface of the enrichment chamber 12 is coated with a superhydrophobic coating; to enhance the filtering effect, the microporous filter membrane 14 is made of a nano-enhanced composite membrane. In this way, the water permeability can be significantly improved, the blocking situation can be effectively reduced. At the same time, a gradient pore size design can also be adopted to achieve hierarchical capture of microplastic particles of different sizes.

[0049] To improve the stability of the laminar flow, reduce the particle deposition situation, and thus significantly improve the enrichment efficiency of microplastics, a flow deflector is provided at the chamber inlet C of the enrichment chamber 12.

[0050] As a preference, the control unit is a PLC controller.

[0051] In the present invention, by installing a flow sensor at the sample inlet of the automatic sampling head, it is convenient to collect the flow signal of the water sample in real time during the sampling process, and then the flow data can be obtained based on the flow signal. Further, it can be determined in real time whether the amount of the entered sample meets the required detection requirements. When the sample amount meets the detection requirements, the automatic sampling head can be directly controlled to stop working. An environmental sensor is arranged inside the automatic sampling head, which is convenient for collecting the temperature signal and pH value data of the water sample in real time during the sampling process. The filter membrane group is composed of multiple hierarchical filter membranes spaced from top to bottom in sequence, which can form a hierarchical filtration structure. In this way, when the water sample passes through the filter membrane group, large particle pollutants and non-target plastic particles can be efficiently filtered out step by step, and only the target microplastic particles are retained. A saturated sodium chloride solution is filled in the sodium chloride solution chamber. At the same time, it is connected to the filling port at the bottom of the separation chamber through a filling pipeline connected in series with a first liquid pump, which is convenient for sucking the saturated sodium chloride solution by the first liquid pump and quantitatively injecting it into the interior of the separation chamber, so that a density flotation environment can be formed by the saturated sodium chloride solution, which is beneficial to promoting the flotation and density separation process of the microplastic particles. In this way, when the water sample enters through the chamber inlet B, it is convenient to quickly and effectively separate the microplastic particles in the water sample from other particles by the density flotation method, so that the microplastic particles can be guided to enrich in the upper layer area, while the heavier particles precipitate to the bottom. On this basis, a transverse chute is arranged in the separation chamber, and a transverse partition is driven to slide in the transverse chute by a partition driving mechanism, which is convenient for dividing the separation chamber into an upper chamber and a lower chamber. In this way, the target microplastic particles can be retained in the water sample in the upper chamber, and thus the preliminary screening of the water sample is realized. By connecting an overflow pipeline A connected in series with a second liquid pump through an overflow hole A at the upper part of the separation chamber, it is convenient to transport the water sample after density separation to the enrichment chamber by the second liquid pump for subsequent concentration operation. The microporous filter membrane is arranged at the lower edge of the overflow hole B, which is convenient to ensure that the high-concentration microplastic suspension obtained after separation and filtration can smoothly pass through the overflow pipeline B and the fourth liquid pump and enter the detection chamber for subsequent detection process. A drain pipeline B connected in series with a third liquid pump is connected to the chamber outlet C at the bottom of the enrichment chamber, which is convenient for the third liquid pump to provide negative pressure. Due to the large resistance of the microporous filter membrane, the filtration efficiency can be significantly improved by providing negative pressure, and it can be ensured that the water sample can smoothly flow to the microporous filter membrane, thereby shortening the concentration filtration time. The outlet end of the overflow pipeline B connected in series with the fourth liquid pump extends into the detection area inside the detection chamber and is connected with a liquid outlet elbow, which is convenient for extracting the high-concentration microplastic suspension and quantitatively dripping it onto the detection platform, so as to facilitate the subsequent detection of the microplastic particles by the Raman probe. The detection platform is installed on a three-dimensional motion platform located in the detection chamber, which is convenient for using the three-dimensional motion platform to conveniently and accurately change the position of the detection platform in the X direction, Y direction and Z direction.By coating a superhydrophobic SERS substrate at the center position of the upper surface of the detection platform, the superhydrophobic SERS substrate can be used to greatly enhance the Raman spectral signal generated when microplastic particles are irradiated by laser, which is conducive to improving the detection accuracy. By arranging a heating plate inside the detection platform, it is convenient to promote the rapid evaporation of water in the sample by heating, and enable the microplastic particles to be enriched in the central area of the superhydrophobic SERS substrate, thereby further ensuring the sensitivity and signal-to-noise ratio of SERS spectral signal detection. Connect the Raman probe to the laser through the laser emission optical fiber and to the Raman spectrometer through the laser reception optical fiber, which can not only conveniently receive the laser emitted by the laser and irradiate the microplastic particles at the enrichment point, but also synchronously collect the generated Raman scattering spectral signal and transmit it to the Raman spectrometer.

[0052] Compared with the traditional method, this system can dynamically adjust the sample injection volume by using a flow sensor to ensure the representativeness of the water sample. At the same time, by using the density gradient flotation technology, combined with the dynamic adjustment of the separation area by the transverse baffle, the microplastics are effectively enriched by the microporous filter membrane, reducing the interference of impurities and improving the separation purity. At the same time, based on the superhydrophobic SERS technology on the detection platform, the microplastic particles are highly enriched by the droplet condensation effect, which can significantly enhance the Raman spectral signal, resulting in a significant enhancement of the detection sensitivity and supporting the long-term environmental monitoring and pollution warning requirements. This system can conveniently and efficiently realize the detection operation of microplastic particles in the water environment, with high detection accuracy, and can provide reliable technical support for the treatment of microplastic pollution in the water environment.

[0053] The present invention also provides a method for on-line intelligent monitoring of microplastics in water environment, which adopts an on-line intelligent monitoring system for microplastics in water environment, including the following steps;

[0054] Step 1: Fill the saturated sodium chloride solution in the sodium chloride solution chamber 9, and then place the on-line intelligent monitoring system for microplastics in water environment near the water environment to be detected;

[0055] Step 2: Control the first liquid pump 10 to start working through the control unit, and use the first liquid pump 10 to inject the saturated sodium chloride solution into the separation chamber 5 until the set capacity is reached, and then stop the first liquid pump 10;

[0056] Step 3: Insert the automatic sampling head 1 into the water environment, and control the automatic sampling head 1 to start working through the control unit. Transport the water sample to the pretreatment chamber 3 through the sampling pipeline 27. Meanwhile, use the flow sensor 35 to collect the flow signal of the sample injection in real time, use the environmental sensor 2 to collect the physical and chemical signals of the sample injection in real time, and send the flow signal, physical and chemical signals to the control unit in real time. The control unit obtains the flow data of the sample according to the flow signal, and obtains the temperature data and pH value data of the sample according to the physical and chemical signals. When the flow quantity of the sample reaches the set flow sampling threshold, control the automatic sampling head 1 to stop the sampling operation;

[0057] Step 4: In the pretreatment chamber 3, use multiple hierarchical filter membranes in the filter membrane group 4 to filter the water sample step by step, filter out non-target pollutants and large-particle-size particles, and only retain the particles below the target size in the water sample to ensure the accuracy of subsequent detection. Then, use the connecting pipeline 28 to divert the filtered water sample to the separation chamber 5 to enter the subsequent separation process;

[0058] Step 5: In the separation chamber 5, use the pre-injected saturated sodium chloride solution to quickly and effectively separate the microplastics and other particles in the water sample by density flotation method. After the separation is completed, the lighter microplastic particles are enriched in the upper region of the liquid, and the heavier particles settle in the lower region of the liquid, such as sand grains, mineral particles, etc. Control the partition driving mechanism 7 to start working, and drive the transverse partition 6 to slowly move to the left in the horizontal direction to prevent water flow disorder and avoid the microplastic particles being stirred to the bottom due to turbulence until the separation chamber 5 is divided into an upper chamber and a lower chamber;

[0059] Step 6: Control the second liquid pump 11 to start working, transport the water sample in the upper chamber to the enrichment chamber 12. Meanwhile, control the third liquid pump 13 to start working to provide negative pressure for the filtration of the water sample, and use the microporous filter membrane 14 to separate and filter the microplastics to obtain a high-concentration microplastic suspension;

[0060] Step 7: First, control the three-dimensional motion platform 17 to move in the X direction until it moves to the left end of the horizontal sliding track, and then control the three-dimensional motion platform 17 to move in the Y direction and Z direction until the detection platform 39 is at a set distance directly below the liquid outlet elbow 39. Then, control the fourth liquid pump 15 to start working, transport the high-concentration microplastic suspension above the microporous filter membrane 14 to the detection chamber 21, and drip it onto the superhydrophobic SERS substrate on the detection platform 16 through the liquid outlet elbow 39;

[0061] Step Eight: First, control the heating plate in the detection platform 16 to start working and heat the microplastic suspension on the superhydrophobic SERS substrate to promote the evaporation of the liquid. During the evaporation process, utilize the polycondensation effect of the superhydrophobic SERS substrate to cause the microplastic particles to aggregate towards the central minimum contact area, forming a high-concentration enrichment point at the center of the superhydrophobic SERS substrate. By enriching the microplastic particles to a smaller area, it is convenient to improve the detection accuracy and can also improve the sensitivity of the SERS spectral signal. Then, control the three-dimensional motion platform 17 to move in the X direction, Y direction, and Z direction until the detection platform 16 moves to a set distance directly below the Raman probe 18. In this way, it can ensure that the Raman probe 18 can be aligned with the formed high-concentration enrichment point.

[0062] Step Nine: Control the laser 20 to start working, and emit irradiation laser towards the microplastic particles in the high-concentration enrichment point through the laser emission optical fiber 19. The excited microplastic particles generate Raman scattering spectral signals. At the same time, utilize the superhydrophobic SERS substrate to enhance the Raman scattering spectral signals generated on the surface of the microplastic particles to form SERS Raman scattering spectral signals. At the same time, receive the SERS Raman scattering spectral signals through the laser receiving optical fiber 25 and transmit them to the Raman spectrometer 26. During this process, the concentration of the Raman probe 18 can be adjusted by means of autofocus, which can further optimize the signal acquisition quality.

[0063] The Raman spectrometer 26 obtains SERS Raman spectral data based on the SERS Raman scattering spectral signals, and uses a background subtraction algorithm to remove the interference signals of the solvent and the substrate. At the same time, uses noise filtering to optimize the spectral quality to improve data stability, and automatically matches the spectral features through principal component analysis and machine learning algorithms, and then compares them with the massive sample data in the microplastic database to determine the type of microplastic. At the same time, calibrate the spectral curve in combination with the intensity of the SERS Raman scattering spectral signals, and calculate the concentration of the microplastic using the integral area of the Raman peak.

[0064] As an option, the microplastic database can be set in the data storage module.

[0065] In order to be able to perform a cleaning operation on the detection platform so as to enable continuous long-term detection operations, in step eight, after the Raman spectroscopy detection operation of microplastics is completed, first control the three-dimensional motion platform 17 to move in the X direction until it moves to the right end of the transverse sliding track through the transverse passage 38, and then control the three-dimensional motion platform 17 to move in the Y direction and the Z direction until the detection platform 16 moves directly below the cleaning mechanism 24 and comes into contact with the cleaning mechanism 24; then control the cleaning drive mechanism 23 to start working, so as to drive the cleaning mechanism 24 to perform a rotational action through the motion link 22 to clean the upper surface of the detection platform 16. After the cleaning operation is completed, control the three-dimensional motion platform 17 to move so that the detection platform 16 reaches directly below the liquid outlet elbow 39 in the detection area 36 again.

[0066] As an option, when multi-cycle detection is required, steps two to eight can be repeatedly executed multiple times.

[0067] As an option, in step four, when it is necessary to discharge the heavy particles and impurities deposited at the bottom of the separation chamber 5, first control the partition drive mechanism 7 to start working, drive the transverse partition 6 to move slowly in the horizontal direction until the separation chamber 5 is divided into an upper chamber and a lower chamber, and then control the electronic valve 8 to open the chamber outlet B to discharge the heavy particles and impurities at the bottom through the drain pipe A29. After the discharge is completed, close the electronic valve 8. Then, control the first liquid pump 10 to start working for a set time, and use the first liquid pump 10 to fill the separation chamber 5 with saturated sodium chloride solution until the set capacity is reached, and then stop the first liquid pump 10. By regularly discharging the deposited heavy particles and impurities, it can effectively prevent them from interfering with the enrichment process of microplastics, which is beneficial to improving the detection accuracy. At the same time, by replenishing and adding the saturated sodium chloride solution, it is beneficial to maintain the density flotation environment in the separation chamber, and thus can ensure that the microplastic particles can stably suspend in the upper water body.

[0068] In view of the limitations of existing microplastic detection technologies, the present invention provides an automated intelligent detection method for microplastics in water environment based on membrane filtration, superhydrophobic enrichment, and surface-enhanced Raman spectroscopy (SERS) technology. Specifically, during the sampling process, the feedback signal of the flow sensor can be used to dynamically adjust the sample injection volume, which is conducive to achieving quantitative sampling. A hierarchical filtration structure is formed by multiple hierarchical filter membranes to filter the water sample, which can efficiently filter out large particle pollutants and non-target plastic particles step by step, and only retain the target microplastic particles. First, a certain amount of saturated sodium chloride solution is injected into the separation chamber, and then the filtered sample is diverted into the separation chamber. The density gradient flotation technology can be used to enrich the microplastics in the upper region of the liquid. By combining the lateral partition to dynamically adjust the separation region, a water sample containing microplastic particles can be obtained based on density separation. Then, the microfiltration membrane filtration technology is adopted in the enrichment chamber to achieve preliminary enrichment of microplastics. Then, the high-concentration microplastic suspension after preliminary enrichment is dropped onto the detection platform, and the microplastic particles are further concentrated through the superhydrophobic surface. At the same time, the evaporation of water is assisted by heating to obtain a high-concentration enrichment point, significantly enhancing the detection sensitivity. By combining SERS technology, this method can detect microplastics with high sensitivity under low-concentration conditions while retaining their chemical fingerprint information.

[0069] This method integrates automatic sampling, density gradient separation, dynamic adjustment of the separation region by lateral partition, enrichment and concentration, superhydrophobic SERS detection, and intelligent analysis of detection data, and can realize the whole-process automated detection process of microplastic particles in the water environment. Moreover, the whole detection process can be carried out without manual intervention, reducing manual operation and analysis errors, improving the detection efficiency and long-term stability, and meeting the requirements for rapid, accurate, and efficient detection of microplastics in the water environment. The implementation process of this method is simple and highly intelligent, and it can provide efficient and convenient technical support for environmental monitoring, drinking water safety assessment, and microplastic pollution control.

Claims

1. An online intelligent monitoring system for microplastics in aquatic environments, comprising a sampling and preprocessing unit, characterized in that: It also includes a microplastic detection and analysis unit and an enrichment and concentration unit; The sampling and pretreatment unit comprises a pretreatment chamber (3), an automatic sampling head (1), a flow sensor (35), an environmental sensor (2), a filter membrane group (4), a separation chamber (5), an electronic valve (8), a transverse partition (6), a partition driving mechanism (7), a sodium chloride solution chamber (9) and a first liquid pump (10); the top and bottom of the pretreatment chamber (3) are respectively provided with a chamber inlet A and a chamber outlet A, and a sampling pipeline (27) is connected to the chamber inlet A; the automatic sampling head (1) is installed at The inlet end of the sampling pipeline (27); the flow sensor (35) is installed at the sampling port of the automatic sampling head (1); the environmental sensor (2) is installed in the inner cavity of the automatic sampling head (1); the filter membrane group (4) is installed transversely in the middle section of the pretreatment chamber (3), the filter membrane group (4) is composed of a plurality of layered filter membranes distributed in sequence from top to bottom, and the filter holes of the plurality of layered filter membranes gradually decrease from top to bottom; the separation chamber (5) is located below the pretreatment chamber (3), and the top and bottom of the separation chamber (5) are respectively provided with chamber inlets B and a chamber outlet B, a filling port is provided at the bottom of one side, an overflow port A is provided at the upper part of one side, and the chamber inlet B is connected to the chamber outlet A through a connecting pipe (28), the chamber outlet B is connected to a discharge pipe A (29), the filling port is connected to a filling pipe (30), and the overflow port A is connected to an overflow pipe A (31), and a partition slide groove is provided horizontally on the right side of the lower part of the separation chamber (5); the electronic valve (8) is installed in the chamber outlet B; the transverse partition (6) can be slidably inserted in the partition slide groove and is completely After sliding into the separation chamber (5), the separation chamber (5) is divided into an upper chamber and a lower chamber; the partition driving mechanism (7) is installed outside the separation chamber (5), and its output end is connected to the right end of the transverse partition (6) to drive the transverse partition (6) to reciprocate in the transverse direction; the sodium chloride solution chamber (9) is located on one side outside the separation chamber (5), and a liquid discharge port is opened at the bottom thereof, and is connected to the liquid inlet end of the filling pipeline (30) through the liquid discharge port; the first liquid pump (10) is connected in series to the filling pipeline (30); The microplastic detection and analysis unit comprises a detection chamber (21), a laser (20), a Raman spectrometer (26), a three-dimensional motion platform (17), a detection platform (16) and a Raman probe (18); the detection chamber (21) is arranged on the right side of the partition chamber (5), a detection area (36) is arranged on the left side inside the detection chamber (21), a detection channel connected to the detection area (36) is opened on the left side, and a probe mounting hole is opened on the upper side in the central area of ​​the detection area (36); the laser (20) and the Raman spectrometer (26) are both arranged on the outside of the detection chamber (21); the three-dimensional motion platform (17) is installed on the bottom side of the detection chamber (21); the detection platform (16) is fixedly installed on the support platform of the three-dimensional motion platform (17); the Raman probe (18) is fixedly inserted into the probe mounting hole, and is connected to the laser (20) through a laser emitting optical fiber (19), and is connected to the Raman spectrometer (26) through a laser receiving optical fiber (25); The enrichment and concentration unit comprises an enrichment chamber (12), a microporous filtration membrane (14), a second liquid pump (11), a third liquid pump (13) and a fourth liquid pump (15); the enrichment chamber (12) is located between the separation chamber (5) and the detection chamber (21), and has a chamber inlet C and a chamber outlet C at its top and bottom, respectively; an overflow port B is provided at the upper portion of one side thereof, and the chamber inlet C is connected to the liquid outlet end of the overflow pipeline A (31), the chamber outlet C is connected to the discharge pipeline B (32), and the overflow port B is connected to the overflow pipeline A (32). An overflow pipeline B (33) is connected, and the outlet end of the overflow pipeline B (33) extends to the left side of the detection area (36) through the detection channel, and is connected to a liquid outlet elbow (39); the microporous filter membrane (14) is installed horizontally inside the enrichment chamber (12) and is located at the lower edge of the overflow port B; the second liquid pump (11) is connected in series to the overflow pipeline A (31); the third liquid pump (13) is connected in series to the discharge pipeline B (32); and the fourth liquid pump (15) is connected in series to the overflow pipeline B (33).

2. The online intelligent monitoring system for microplastics in water environment according to claim 1 is characterized in that: The microplastic detection and analysis unit further comprises a vertical partition (34), a motion connecting rod (22), a cleaning mechanism (24) and a cleaning drive mechanism (23); A cleaning area (37) is provided on the right side of the detection chamber (21), and a cleaning passage connected to the cleaning area (37) is opened on the right side; the vertical partition (34) is fixedly installed in the upper space inside the detection chamber (21), and the detection area (36) and the cleaning area (37) are respectively formed in the left space and the right space of the vertical partition (34); a set distance is left between the lower edge of the vertical partition (34) and the bottom plate of the detection chamber (21), and a horizontal passage (38) is formed; a horizontal sliding track is installed on the bottom plate inside the detection chamber (21); and the three-dimensional motion platform (17) is installed on the horizontal sliding track; The moving link (22) is rotatably mounted in the cleaning channel; the cleaning mechanism (24) is located in the cleaning area (37) and is fixedly mounted on the left end of the moving link (22); the cleaning drive mechanism (23) is arranged outside the detection chamber (21), and its output end is connected to the right end of the moving link (22).

3. The online intelligent monitoring system for microplastics in water environment according to claim 1 is characterized in that: The detection platform (16) is made of a low-fluorescence background material, and a super-hydrophobic SERS substrate is coated at the center of its upper surface, and a heating plate is arranged inside it.

4. The online intelligent monitoring system for microplastics in water environment according to claim 3 is characterized in that: The invention also comprises a control unit, which is respectively connected to the flow sensor (35), the environmental sensor (2), the automatic sampling head (1), the electronic valve (8), the partition driving mechanism (7), the first liquid pump (10), the laser (20), the Raman spectrometer (26), the three-dimensional motion platform (17), the second liquid pump (11), the third liquid pump (13), the fourth liquid pump (15), the cleaning driving mechanism (23) and the heating plate.

5. The online intelligent monitoring system for microplastics in water environment according to claim 1 is characterized in that: The inner surface of the enrichment chamber (12) is coated with a super-hydrophobic coating; and the microporous filtration membrane (14) is made of a nano-enhanced composite membrane.

6. The online intelligent monitoring system for microplastics in water environment according to claim 1 is characterized in that: A guide plate is provided at the chamber inlet C of the enrichment chamber (12).

7. The online intelligent monitoring system for microplastics in water environment according to claim 1 is characterized in that: The control unit is a PLC controller.

8. An online intelligent monitoring method for microplastics in water environment, using an online intelligent monitoring system for microplastics in water environment as claimed in any one of claims 1 to 7, characterized in that: The steps include: Step 1: Fill the sodium chloride solution chamber (9) with a saturated sodium chloride solution, and then place the water environment microplastic online intelligent monitoring system near the water environment to be detected; Step 2: Controlling the first liquid pump (10) to start working by means of the control unit, and using the first liquid pump (10) to add saturated sodium chloride solution into the separation chamber (5) until a set capacity is reached, and then stopping the first liquid pump (10); Step 3: Extend the automatic sampling head (1) into the water environment, and control the automatic sampling head (1) to start working through the control unit, and transport the water sample to the pretreatment chamber (3) through the sampling pipeline (27). At the same time, use the flow sensor (35) to collect the flow signal of the sample in real time, use the environmental sensor (2) to collect the physical and chemical signals of the sample in real time, and send the flow signal, physical and chemical signals to the control unit in real time. The control unit obtains the flow data of the sample according to the flow signal, and obtains the temperature data and pH value data of the sample according to the physical and chemical signals. When the flow quantity of the sample reaches the set flow sampling threshold, the automatic sampling head (1) is controlled to stop the collection operation; Step 4: In the pretreatment chamber (3), the water sample is filtered step by step using the multiple filter membranes in the filter membrane group (4) to remove non-target pollutants and large-sized particles, and only particles below the target size are retained in the water sample. The filtered water sample is then directed to the separation chamber (5) using the connecting pipe (28); Step 5: In the separation chamber (5), the microplastics and other particles in the water sample are quickly and effectively separated by density flotation using a pre-filled saturated sodium chloride solution. After the separation is completed, the lighter microplastic particles are concentrated in the upper layer of the liquid, and the heavier particles are settled in the lower layer of the liquid; the partition drive mechanism (7) is controlled to start working, and the transverse partition (6) is driven to move slowly to the left in the transverse direction until the separation chamber (5) is separated into an upper chamber and a lower chamber; Step 6: Control the second liquid pump (11) to start working, and transport the water sample in the upper chamber to the enrichment chamber (12). At the same time, control the third liquid pump (13) to start working to provide negative pressure for filtering the water sample, and use the microporous filter membrane (14) to separate and filter the microplastics, and obtain a high-concentration microplastic suspension after separation and filtration; Step 7: First, the three-dimensional motion platform (17) is controlled to move in the X direction until it moves to the left end of the lateral sliding track, and then the three-dimensional motion platform (17) is controlled to move in the Y direction and the Z direction until the detection platform (39) is located at a set distance directly below the liquid outlet elbow (39); then the fourth liquid pump (15) is controlled to start working, and the high-concentration microplastic suspension above the microporous filter membrane (14) is transported to the detection chamber (21), and dripped onto the super-hydrophobic SERS substrate on the detection platform (16) through the liquid outlet elbow (39); Step 8: First, the heating plate in the detection platform (16) is controlled to start working, and the microplastic suspension on the super-hydrophobic SERS substrate is heated to promote the evaporation of the liquid. During the evaporation process, the microplastic particles are aggregated to the central minimum contact area by using the condensation effect of the super-hydrophobic SERS substrate, and a high-concentration enrichment point is formed in the center of the super-hydrophobic SERS substrate; then the three-dimensional motion platform (17) is controlled to move in the X direction, the Y direction and the Z direction until the detection platform (16) moves to a set distance directly below the Raman probe (18); Step nine: Control the laser (20) to start working, emit irradiation laser to the microplastic particles in the high-concentration enrichment point through the laser emitting optical fiber (19), and at the same time, use the super-hydrophobic SERS substrate to enhance the Raman scattering spectrum signal generated on the surface of the microplastic particles to form a SERS Raman scattering spectrum signal; at the same time, receive the SERS Raman scattering spectrum signal through the laser receiving optical fiber (25) and transmit it to the Raman spectrometer (26); The Raman spectrometer (26) obtains SERS Raman spectral data based on the SERS Raman scattering spectral signal, and uses a background subtraction algorithm to remove the interference signals of the solvent and substrate. At the same time, noise filtering is used to optimize the spectral quality, and the spectral features are automatically matched through principal component analysis and machine learning algorithms. The spectral features are then compared with the massive sample data in the microplastic database to determine the type of microplastics. At the same time, the spectral curve is calibrated in combination with the SERS Raman scattering spectral signal intensity, and the concentration of the microplastics is calculated using the Raman peak integral area.

9. The method for online intelligent monitoring of microplastics in aquatic environment according to claim 8, characterized in that: In step eight, after the Raman spectrum detection operation of microplastics is completed, the three-dimensional motion platform (17) is first controlled to move in the X direction until it moves to the right end of the lateral sliding track through the lateral passage (38), and then the three-dimensional motion platform (17) is controlled to move in the Y direction and the Z direction until the detection platform (16) moves to the bottom of the cleaning mechanism (24) and contacts the cleaning mechanism (24); then the cleaning drive mechanism (23) is controlled to start working, so as to drive the cleaning mechanism (24) to rotate through the motion connecting rod (22) to clean the upper surface of the detection platform (16).

10. The method for online intelligent monitoring of microplastics in aquatic environment according to claim 9, characterized in that: In step 4, when it is necessary to discharge the heavy particles and impurities deposited at the bottom of the separation chamber (5), the partition driving mechanism (7) is first controlled to start working, driving the transverse partition (6) to slowly move in the transverse direction until the separation chamber (5) is separated into an upper chamber and a lower chamber, and then the electronic valve (8) is controlled to open the chamber outlet B, and the heavy particles and impurities at the bottom are discharged through the discharge pipeline A (29). After the discharge is completed, the electronic valve (8) is closed, and then the first liquid pump (10) is controlled to start working for a set time, and the saturated sodium chloride solution is added into the separation chamber (5) by using the first liquid pump (10) until the set capacity is reached, and then the first liquid pump (10) is stopped.

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