An online intelligent monitoring system and method for microplastics in a water environment

Abstract

An online intelligent monitoring system and method for microplastics in water environment, the system comprising: a filter membrane group arranged in a pretreatment chamber, an inlet of the filter membrane group being connected with an automatic sampling head, an inlet of a separation chamber being connected with an outlet of the pretreatment chamber, a filling port of the separation chamber being connected with an outlet of a sodium chloride solution chamber, and an electronic valve being arranged at an outlet of the separation chamber; an enrichment chamber being connected with an overflow port of the separation chamber, and a microporous filter membrane being arranged in the enrichment chamber; an overflow pipeline of the enrichment chamber extending to a detection chamber; a three-dimensional motion platform being arranged in the detection chamber, and a detection platform being arranged on the three-dimensional motion platform; a Raman probe being arranged in the detection chamber and being connected with a laser and a Raman spectrometer respectively. The method comprising: collecting water samples, performing multi-stage filtration in the pretreatment chamber, performing density floatation in the separation chamber, performing concentration in the enrichment chamber, performing enrichment in the detection platform, and performing analysis by using laser irradiation and synchronously collecting Raman spectrum signals. The system and the method can realize qualitative analysis of microplastics in water environment.

Description

Technical Field

[0001] This invention belongs to the field of intelligent monitoring technology, specifically an online intelligent monitoring system and method for microplastics in the water environment. Background Technology

[0002] Microplastics are plastic particles with a diameter of less than 5 millimeters. With the escalating global plastic pollution problem, microplastics have gradually become a significant component of water pollution. Microplastics are widely present in various water bodies worldwide, including oceans, lakes, rivers, and groundwater. Due to their small size and high persistence, microplastics can persist in the aquatic environment for extended periods and enter ecosystems through biological ingestion, thus affecting the growth, reproduction, and even survival of aquatic organisms. More importantly, microplastics can adsorb harmful chemicals in water, such as heavy metals and persistent organic pollutants. The adhesion of these substances not only makes the microplastics themselves toxic but may also be continuously transferred through the food chain, ultimately affecting human health. As research progresses, the health risks posed by microplastics are becoming increasingly apparent, especially the potential for microplastic contamination in drinking water, a situation that presents an extremely serious challenge to public health. Therefore, developing an efficient, sensitive, and automated intelligent detection technology for microplastics in water bodies is a crucial requirement for water environmental protection and public health safety.

[0003] Currently, microplastic detection methods mainly rely on several traditional techniques, including microscopy, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and pyrolysis-gas chromatography-mass spectrometry (Py-GC / MS). Microscopy is the most intuitive method, requiring manual observation of microplastic particles in the sample; however, this method is inefficient and easily affected by human factors, making high-throughput detection difficult. FTIR and Raman spectroscopy have significant advantages in providing chemical information about microplastic composition, especially in the qualitative analysis of microplastics. However, traditional Raman and FTIR methods have poor sensitivity at low microplastic concentrations and are complex to operate, failing to meet the needs 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 preparation, it is suitable for laboratory environments but not for large-scale on-site monitoring. Although some emerging technologies (such as spectral analysis and microfluidic chips) have made some progress in recent years, their detection efficiency, equipment cost, and complex operating procedures still make it difficult to meet the actual needs for rapid, accurate, and efficient detection of microplastics in water bodies. Therefore, developing a new detection technology that integrates high sensitivity, low cost, rapid analysis, and automated detection has become an urgent task in the current prevention and control of microplastic pollution. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides an online intelligent monitoring system and method for microplastics in aquatic environments. This system can conveniently and efficiently detect microplastic particles in aquatic environments with high accuracy, providing reliable technical support for the remediation of microplastic pollution in water bodies. The method is simple to implement and highly intelligent, integrating high sensitivity, low cost, rapid analysis, and automated detection functions, enabling qualitative analysis of microplastics in aquatic environments.

[0005] To achieve the above objectives, the present invention provides an online intelligent monitoring system for microplastics in the water environment, comprising 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 assembly, a separation chamber, an electronic valve, a transverse partition, a partition drive mechanism, a sodium chloride solution chamber, and a first liquid pump. The pretreatment chamber has a chamber inlet A at its top and a chamber outlet A at its bottom, 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 inlet of the automatic sampling head. The environmental sensor is installed inside the automatic sampling head. The filter membrane assembly is installed transversely in the middle section of the pretreatment chamber, and the assembly consists of multiple layered filter membranes distributed sequentially from top to bottom, with the pore size of the layered filter membranes gradually decreasing from top to bottom. The separation chamber is located below the pretreatment chamber, and has a chamber inlet B at its top and a chamber outlet B at its bottom. A filling port is provided at the bottom of one side, and an overflow port A is provided at the top of the same side. The chamber inlet B is connected to the chamber outlet A via a connecting pipe. The chamber outlet B is connected to a drain pipe A. The filling port is connected to a filling pipe, and the overflow port A is connected to an overflow pipe A. A partition groove is provided laterally on 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 groove and, after being fully inserted into the separation chamber, divides the separation chamber into an upper chamber and a lower chamber. The partition drive mechanism is installed outside the separation chamber, and its output end is connected to the right end of the transverse partition to drive the transverse partition to reciprocate laterally. The sodium chloride solution chamber is located on one side outside the separation chamber, and a drain port is provided at its bottom, which is connected to the inlet end of the filling pipe. The first liquid pump is connected in series on the filling pipe.

[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 located on the right side of the partitioned chamber, with a detection area on the left side inside. A detection channel connecting to the detection area is opened on the left side of the detection chamber, and a probe mounting hole is opened in the center area of ​​the detection area on the upper side. The laser and Raman spectrometer are both located 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 platform 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 emitting fiber, and simultaneously connected to the Raman spectrometer through a laser receiving 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. It has a chamber inlet C at its top and a chamber outlet C at its bottom. An overflow port B is located on the upper part of one side. The chamber inlet C is connected to the outlet end of the overflow pipe A. The chamber outlet C is connected to the drain pipe B. The overflow port B is connected to the overflow pipe B, and the outlet end of the overflow pipe B extends through the detection channel to the left side of the detection area and is connected to an outlet elbow. The microporous filter membrane is installed laterally inside the enrichment chamber and is located at the lower edge of the overflow port B. The second liquid pump is connected in series with the overflow pipe A. The third liquid pump is connected in series with the drain pipe B. The fourth liquid pump is connected in series with the overflow pipe B.

[0009] Furthermore, to enable the system to have an automatic cleaning function and ensure detection accuracy and stability during long-term continuous operation, the microplastic detection and analysis unit also includes a vertical partition, a moving link, a cleaning mechanism, and a cleaning drive mechanism. A cleaning zone is located on the right side of the detection chamber, with a cleaning channel connecting to the cleaning zone on its right side. The vertical partition is fixedly installed in the upper space inside the detection chamber, with the detection zone and cleaning zone formed in the left and right spaces of the vertical partition, respectively. A set distance is left between the lower end of the vertical partition and the bottom plate of the detection chamber, forming a transverse passage. A transverse sliding track is installed on the bottom plate inside the detection chamber. The three-dimensional motion platform is installed on the transverse sliding track. The moving link is rotatably installed in the cleaning channel. The cleaning mechanism is located in the cleaning zone and fixedly installed on the left end of the moving link. The cleaning drive mechanism is located outside the detection chamber, with its output end connected to the right end of the moving link.

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

[0011] Furthermore, to facilitate fully automated detection operations, a control unit is also included. The control unit is connected to a flow sensor, an environmental sensor, an automatic sampling head, an electronic valve, a baffle drive 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 drive mechanism, and a heating plate.

[0012] Furthermore, 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-reinforced composite membrane.

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

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

[0015] In this invention, by installing a flow sensor at the inlet of the automatic sampling head, the flow rate signal of the water sample can be collected in real time during the sampling process. Based on this flow rate signal, flow data can be obtained, and it can be determined in real time whether the amount of sample entering the 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 installed inside the automatic sampling head to facilitate the real-time collection of water sample temperature and pH data during sampling. The filter membrane assembly consists of multiple layered filter membranes distributed at intervals from top to bottom, forming a layered filtration structure. Thus, when the water sample passes through the filter membrane assembly, large particulate pollutants and non-target plastic particles can be filtered out efficiently step by step, retaining only the target microplastic particles. The sodium chloride solution chamber is filled with saturated sodium chloride solution. A filling pipeline connected in series with a first liquid pump is connected to the filling port at the bottom of the separation chamber. This allows the first liquid pump to draw up the saturated sodium chloride solution and quantitatively inject it into the separation chamber. The saturated sodium chloride solution creates a density flotation environment, which facilitates the flotation and density separation of microplastic particles. When a water sample enters through chamber inlet B, density flotation can quickly and effectively separate the microplastic particles from other particles, guiding the microplastic particles to the upper region for enrichment, while heavier particles settle to the bottom. Furthermore, a transverse chute is installed in the separation chamber, and a baffle drive mechanism drives the transverse baffle to slide within the chute, easily dividing the separation chamber into an upper and lower chamber. This retains the target microplastic particles in the water sample in the upper chamber, thus achieving preliminary screening of the water sample. By connecting an overflow pipe A, which is connected in series with a second liquid pump, to the upper part of the separation chamber via an overflow hole A, the water sample after density separation can be easily transported to the enrichment chamber by the second liquid pump for subsequent concentration. Placing a microporous filter membrane at the lower edge of the overflow hole B ensures that the high-concentration microplastic suspension obtained after separation and filtration can smoothly pass through the overflow pipe B and the fourth liquid pump into the detection chamber for subsequent detection. Connecting a drain pipe B, which is connected in series with a third liquid pump, to the chamber outlet C at the bottom of the enrichment chamber allows the third liquid pump to provide negative pressure. Due to the high resistance of the microporous filter membrane, providing negative pressure significantly improves filtration efficiency and ensures that the water sample flows smoothly to the microporous filter membrane, thereby shortening the concentration and filtration time. The overflow pipe B, connected in series with a fourth liquid pump, extends into the detection area of ​​the detection chamber and is connected to an outlet elbow. This facilitates the extraction of high-concentration microplastic suspensions and their quantitative addition to the detection platform, enabling subsequent Raman probe detection of microplastic particles. The detection platform is mounted on a three-dimensional motion platform located within the detection chamber, allowing for convenient and precise adjustments to its position in the X, Y, and Z directions.By coating the center of the upper surface of the detection platform with a superhydrophobic SERS substrate, the Raman spectral signal generated when microplastic particles are irradiated by a laser can be significantly enhanced, thereby improving detection accuracy. An internal heating plate facilitates rapid evaporation of moisture from the sample through heating, allowing microplastic particles to accumulate in the central region of the superhydrophobic SERS substrate, further ensuring the sensitivity and signal-to-noise ratio of the SERS spectral signal. The Raman probe is connected to the laser via a laser emitting fiber and to the Raman spectrometer via a laser receiving fiber. This allows for convenient reception of the laser beam emitted by the laser and its application to the microplastic particles at the accumulation point, while simultaneously acquiring and transmitting the generated Raman scattering spectral signal to the Raman spectrometer.

[0016] Compared to traditional methods, this system uses a flow sensor to dynamically adjust the sample injection volume, ensuring the representativeness of the water sample. It also utilizes density gradient flotation technology, combined with a transverse baffle to dynamically adjust the separation zone, and a microporous filter membrane to effectively enrich microplastics, reducing impurity interference and improving separation purity. Furthermore, based on superhydrophobic SERS technology on the detection platform, the system utilizes droplet condensation effect to highly enrich microplastic particles, significantly enhancing the Raman spectral signal and resulting in significantly improved detection sensitivity, supporting long-term environmental monitoring and pollution early warning needs. This system can conveniently and efficiently detect microplastic particles in aquatic environments with high accuracy, providing reliable technical support for the remediation of microplastic pollution in aquatic environments.

[0017] The present invention also provides an online intelligent monitoring method for microplastics in the water environment, which employs an online intelligent monitoring system for microplastics in the water environment and includes the following steps;

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

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

[0020] Step 3: Insert the automatic sampling head into the water environment and control it to start operation via the control unit. Water samples are transported to the pretreatment chamber through the sampling pipeline. Simultaneously, a flow sensor collects the sample flow rate signal in real time, and an environmental sensor collects the physical and chemical signals of the sample in real time. These signals are then sent to the control unit in real time. The control unit obtains the sample flow rate data based on the flow rate signal and the sample temperature and pH value data based on the physical and chemical signals. When the sample flow rate reaches the set flow rate sampling threshold, the automatic sampling head stops collecting samples.

[0021] Step 4: In the pretreatment chamber, the water sample is filtered step by step using multiple layered filter membranes in the filter membrane assembly to remove non-target pollutants and large-diameter particles, leaving only particles smaller than the target size in the water sample. The filtered water sample is then guided to the separation chamber through the connecting pipe.

[0022] Step 5: In the separation chamber, the microplastics in the water sample are quickly and effectively separated from other particles by density flotation using a pre-filled saturated sodium chloride solution. After separation, the lighter microplastic particles are enriched in the upper layer of the liquid, while the heavier particles settle in the lower layer. The baffle drive mechanism is then activated, driving the transverse baffle to move slowly to the left in the transverse direction until the separation chamber is divided into an upper chamber and a lower chamber.

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

[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 transverse sliding track. Then, control the three-dimensional motion platform to move in the Y and Z directions until the detection platform is located at the set distance directly below the liquid outlet bend. 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 bend.

[0025] Step 8: First, start the heating plate in the detection platform to heat the microplastic suspension on the superhydrophobic SERS substrate to promote liquid evaporation. During the evaporation process, the condensation effect of the superhydrophobic SERS substrate causes 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. Then, control the three-dimensional motion platform to move in the X, Y, and Z directions until the detection platform moves to a set distance directly below the Raman probe.

[0026] Step 9: Control the laser to start working, and emit irradiation laser to the microplastic particles in the high concentration enrichment point through the laser emitting fiber. At the same time, the Raman scattering spectrum signal generated on the surface of the microplastic particles is enhanced by the superhydrophobic SERS substrate to form a SERS Raman scattering spectrum signal. Meanwhile, the SERS Raman scattering spectrum signal is received through the laser receiving fiber and transmitted to the Raman spectrometer.

[0027] The Raman spectrometer obtains SERS Raman spectral data based on SERS Raman scattering spectral signals, and uses a background subtraction algorithm to remove interference signals from the solvent and substrate. At the same time, noise filtering is used to optimize the spectral quality, and principal component analysis and machine learning algorithms are used to automatically match spectral features. The data is then compared with massive sample data in a microplastic database to determine the types of microplastics. In addition, the spectral curve is calibrated by combining the SERS Raman scattering spectral signal intensity, and the concentration of microplastics is calculated using the integrated area of ​​the Raman peak.

[0028] Furthermore, in order to enable the cleaning of the detection platform and facilitate continuous long-term detection operations, in step eight, after the Raman spectroscopy detection of microplastics is completed, the three-dimensional motion platform is first controlled to move in the X direction until it moves to the right end of the transverse sliding track through the transverse passage. Then, the three-dimensional motion platform is controlled to move in the Y and Z directions until the detection platform moves directly below the cleaning mechanism and comes into contact with it. Then, the cleaning drive mechanism is started to operate, so as to drive the cleaning mechanism to rotate through the motion linkage to clean the upper surface of the detection platform.

[0029] As a preferred embodiment, in step four, when it is necessary to discharge the heavy particles and impurities deposited at the bottom of the separation chamber, the baffle drive mechanism is first started to drive the transverse baffle to move slowly in the transverse direction until the separation chamber is divided into an upper chamber and a lower chamber. Then, the electronic valve is controlled to open the chamber outlet B, and the heavy particles and impurities at the bottom are discharged through the drain pipe A. After the discharge is completed, the electronic valve is closed. Then, the first liquid pump is started for a set time, and the saturated sodium chloride solution is added to the separation chamber until the set capacity is reached, and then the first liquid pump is stopped.

[0030] To address the limitations of existing microplastic detection technologies, this invention provides an automated intelligent detection method for microplastics in aquatic environments based on membrane filtration, superhydrophobic enrichment, and surface-enhanced Raman spectroscopy (SERS). Specifically, during sampling, the sample injection volume can be dynamically adjusted using feedback signals from a flow sensor, facilitating quantitative sampling. A multi-layered filter structure is used to filter the water sample, efficiently removing large particulate pollutants and non-target plastic particles while retaining only the target microplastic particles. A certain amount of saturated sodium chloride solution is first injected into the separation chamber, and then the filtered sample is guided into the separation chamber. Density gradient flotation technology can be used to enrich microplastics in the upper layer of the liquid. Combined with a transverse baffle dynamically adjusting the separation area, a water sample containing microplastic particles can be obtained based on density separation. Microporous membrane filtration technology is then used in the enrichment chamber to achieve preliminary enrichment of microplastics. The pre-enriched high-concentration microplastic suspension is then droplet-added onto the detection platform, where the microplastic particles are further concentrated via a superhydrophobic surface. Simultaneously, heating is used to evaporate the water, resulting in high-concentration enrichment points and significantly enhancing detection sensitivity. By combining this method with SERS technology, high-sensitivity detection of microplastics can be achieved under low-concentration conditions while preserving their chemical fingerprint information.

[0031] This method integrates automatic sampling, density gradient separation, dynamic adjustment of the separation region by transverse baffles, enrichment and concentration, superhydrophobic SERS detection, and intelligent analysis of detection data. It enables fully automated detection of microplastic particles in aquatic environments, requiring no manual intervention. This reduces human error and improves detection efficiency and long-term stability, meeting the need for rapid, accurate, and efficient detection of microplastics in aquatic environments. The method is simple to implement and highly intelligent, providing efficient and convenient technical support for environmental monitoring, drinking water safety assessment, and microplastic pollution control. Attached Figure Description

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

[0033] Figure 2 This is a block diagram of the control section in this invention.

[0034] In the diagram: 1. Automatic sampling head; 2. Environmental sensor; 3. Pretreatment chamber; 4. Filter membrane; 5. Separation chamber; 6. Transverse partition; 7. Partition drive 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. Microporous filter membrane; 15. Fourth liquid pump; 16. Detection platform; 17. Three-dimensional motion platform; 18. Raman probe; 19. Laser emitting fiber; 20. 21. Laser, 22. Detection chamber, 23. Motion linkage, 24. Cleaning drive mechanism, 25. Cleaning mechanism, 26. Laser receiving fiber, 27. Raman spectrometer, 28. Sampling pipeline, 29. Connecting pipeline, 30. Drainage pipeline A, 31. Filling pipeline, 32. Overflow pipeline A, 33. Drainage pipeline B, 34. Overflow pipeline B, 35. Vertical partition, 36. Flow sensor, 37. Detection area, 38. Cleaning area, 39. Lateral passage, 30. Discharge elbow. Detailed Implementation

[0035] The invention will now be further described with reference to the accompanying drawings.

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

[0037] The sampling and pretreatment unit includes a pretreatment chamber 3, an automatic sampling head 1, a flow sensor 35, an environmental sensor 2, a filter membrane assembly 4, a separation chamber 5, an electronic valve 8, a transverse partition 6, a partition drive mechanism 7, a sodium chloride solution chamber 9, and a first liquid pump 10. The pretreatment chamber 3 has a chamber inlet A at its top and a chamber outlet A at its bottom, 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. Preferably, the automatic sampling head 1 also includes an automatic timer, so that when started, it can start working according to a set time interval to achieve periodic sampling. The flow sensor 35 is installed at the inlet of the automatic sampling head 1. The environmental sensor 2 is installed inside the automatic sampling head 1. Preferably, the environmental sensor 2 is equipped with a temperature sensor and a pH sensor. The temperature sensor is used to collect the temperature signal of the water sample in real time, and the pH sensor is used to collect the pH data of the water in real time. The filter membrane group 4 is installed horizontally in the middle section of the pretreatment chamber 3. The filter membrane group 4 is composed of multiple layered filter membranes distributed from top to bottom, and the filter pores of the multiple layered filter membranes gradually decrease from top to bottom. Preferably, the multiple layered filter membranes adopt a combination of hydrophilic filter membranes and hydrophobic filter membranes. The hydrophilic filter membrane is used to remove organic matter and suspended solids, while the hydrophobic filter membrane is used to remove oily pollutants, while retaining hydrophobic microplastic particles.

[0038] The separation chamber 5 is located below the pretreatment chamber 3. It has a chamber inlet B at its top and a chamber outlet B at its bottom. A filling port is located at the bottom of one side, and an overflow port A is located at the top of the other side. The chamber inlet B is connected to the chamber outlet A via a connecting pipe 28. The chamber outlet B is connected to a drain pipe A29. The filling port is connected to a filling pipe 30, and the overflow port A is connected to an overflow pipe A31. A partition groove is laterally formed on the lower right side 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 groove and, after fully sliding into the separation chamber 5, divides the separation chamber 5 into an upper chamber and a lower chamber. The right end of the partition groove is located at the right end of the separation chamber 5. A connection port is provided to the outside. To ensure a sealing effect, the connection port and the partition slide groove are slidably sealed together. In this way, when the transverse partition 6 slides outward from the connection port at the right end of the partition slide groove, the internal liquid can be prevented from overflowing to the outside through the connection port. The partition drive mechanism 7 is installed outside the separation chamber 5, and its output end is connected to the right end of the transverse partition 6. It is used to drive the transverse partition 6 to reciprocate in the transverse direction. Preferably, the partition drive mechanism 7 can be 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 provided at its bottom and is connected to the inlet end of the filling pipeline 30 through the drain port. The first liquid pump 10 is connected in series on the filling pipeline 30.

[0039] As a preferred option, a throttling orifice can be provided in the connecting pipe 28 to achieve a buffering effect, prevent violent fluctuations in the water sample, ensure that the microplastic particles can be distributed more evenly in the water sample, and thus improve 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 located on the right side of the partition chamber 5, with a detection area 36 on the left side inside. A detection channel connecting to the detection area 36 is opened on the left side of the chamber, and a probe mounting hole is opened in the center area of ​​the detection area 36 on the upper side. The laser 20 and the Raman spectrometer 26 are both located 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 stepper motor 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 connected to the laser 20 through a laser emitting fiber 19, and simultaneously connected to the Raman spectrometer 26 through a laser receiving 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. It has a chamber inlet C at its top and a chamber outlet C at its bottom. An overflow port B is located on the upper part of one side. The chamber inlet C is connected to the outlet end of the overflow pipe A31. The chamber outlet C is connected to a drain pipe B32. The overflow port B is connected to an overflow pipe B33, and the outlet end of the overflow pipe B33 extends through a detection channel to the detection... On the left side of the test area 36, ​​a liquid outlet elbow 39 is connected, with the liquid outlet end of the liquid outlet elbow 39 located at the lower end; the microporous filter membrane 14 is horizontally installed inside the enrichment chamber 12 and located at the lower edge of the overflow port B, for further solid-liquid separation, so as to retain microplastic particles in the chamber, while allowing the clear liquid to pass through the microporous filter membrane 14 and be discharged through the drain pipe B32; the second liquid pump 11 is connected in series to the overflow pipe A31; the third liquid pump 13 is connected in series to the drain pipe B32; and the fourth liquid pump 15 is connected in series to the overflow pipe B33.

[0042] To enable the system to have an automatic cleaning function, ensuring detection accuracy and stability during long-term continuous operation, the microplastic detection and analysis unit also includes a vertical partition 34, a moving link 22, a cleaning mechanism 24, and a cleaning drive mechanism 23. A cleaning zone 37 is located on the right side of the detection chamber 21, with a cleaning channel connecting to the cleaning zone 37. The vertical partition 34 is fixedly installed in the upper space inside the detection chamber 21, with the detection zone 36 and cleaning zone 37 formed in the left and right spaces of the vertical partition 34, respectively. A set distance is left between the lower end of the vertical partition 34 and the bottom plate of the detection chamber 21, forming a transverse passageway 38. A transverse sliding track is installed on the bottom plate inside the detection chamber 21. The three-dimensional motion platform 17 is installed on the transverse sliding track.

[0043] The motion link 22 is rotatably mounted in the cleaning channel; the cleaning mechanism 24 is located in the cleaning area 37 and fixedly mounted on the left end of the motion link 22; the cleaning drive mechanism 23 is located outside the detection chamber 21, and its output end is connected to the right end of the motion link 22. The cleaning drive mechanism 23 is used to drive the motion link 22 to rotate, and also to drive the motion link 22 to move laterally. Preferably, the cleaning drive mechanism 23 can be composed of a rotary drive motor and a lateral pushing device, wherein the rotary drive motor is used to drive the motion link 22 to rotate, and the lateral pushing device is supported at the bottom of the rotary drive motor and is used to drive the rotary drive motor to move laterally. Preferably, the lateral pushing device is composed of a linear electric push rod motor and a support frame mounted on the telescopic end of the linear electric push rod motor, wherein the rotary drive motor is mounted on the top of the support frame.

[0044] To effectively reduce the interference of fluorescence on the detection results and improve the quality of the Raman signal, the detection platform 16 is made of a low-fluorescence background material, and its upper surface center is coated with a superhydrophobic SERS substrate, with a heating plate inside. As a further preferred embodiment, the upper surface of the detection platform 16 has a high-precision planar structure, capable of supporting enriched and concentrated microplastic samples and ensuring uniform sample distribution.

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

[0046] As a preferred embodiment, the system also includes a power supply module and a communication module. The power supply module is connected to the control unit and is used to supply power. The communication module is connected to the control unit and is used to establish a communication connection between the monitoring system and external devices.

[0047] As a preferred option, a data storage module is also included, which is connected to the control unit and used to build 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 filtration effect, the microporous filter membrane 14 is made of a nano-reinforced composite membrane, which can significantly improve water permeability and effectively reduce clogging. At the same time, a gradient pore size design can be adopted to achieve graded capture of microplastic particles of different sizes.

[0049] In order to improve the stability of laminar flow and reduce particle deposition, thereby significantly improving the enrichment efficiency of microplastics, a guide plate is provided at the chamber inlet C of the enrichment chamber 12.

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

[0051] In this invention, by installing a flow sensor at the inlet of the automatic sampling head, the flow rate signal of the water sample can be collected in real time during the sampling process. Based on this flow rate signal, flow data can be obtained, and it can be determined in real time whether the amount of sample entering the 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 installed inside the automatic sampling head to facilitate the real-time collection of water sample temperature and pH data during sampling. The filter membrane assembly consists of multiple layered filter membranes distributed at intervals from top to bottom, forming a layered filtration structure. Thus, when the water sample passes through the filter membrane assembly, large particulate pollutants and non-target plastic particles can be filtered out efficiently step by step, retaining only the target microplastic particles. The sodium chloride solution chamber is filled with saturated sodium chloride solution. A filling pipeline connected in series with a first liquid pump is connected to the filling port at the bottom of the separation chamber. This allows the first liquid pump to draw up the saturated sodium chloride solution and quantitatively inject it into the separation chamber. The saturated sodium chloride solution creates a density flotation environment, which facilitates the flotation and density separation of microplastic particles. When a water sample enters through chamber inlet B, density flotation can quickly and effectively separate the microplastic particles from other particles, guiding the microplastic particles to the upper region for enrichment, while heavier particles settle to the bottom. Furthermore, a transverse chute is installed in the separation chamber, and a baffle drive mechanism drives the transverse baffle to slide within the chute, easily dividing the separation chamber into an upper and lower chamber. This retains the target microplastic particles in the water sample in the upper chamber, thus achieving preliminary screening of the water sample. By connecting an overflow pipe A, which is connected in series with a second liquid pump, to the upper part of the separation chamber via an overflow hole A, the water sample after density separation can be easily transported to the enrichment chamber by the second liquid pump for subsequent concentration. Placing a microporous filter membrane at the lower edge of the overflow hole B ensures that the high-concentration microplastic suspension obtained after separation and filtration can smoothly pass through the overflow pipe B and the fourth liquid pump into the detection chamber for subsequent detection. Connecting a drain pipe B, which is connected in series with a third liquid pump, to the chamber outlet C at the bottom of the enrichment chamber allows the third liquid pump to provide negative pressure. Due to the high resistance of the microporous filter membrane, providing negative pressure significantly improves filtration efficiency and ensures that the water sample flows smoothly to the microporous filter membrane, thereby shortening the concentration and filtration time. The overflow pipe B, connected in series with a fourth liquid pump, extends into the detection area of ​​the detection chamber and is connected to an outlet elbow. This facilitates the extraction of high-concentration microplastic suspensions and their quantitative addition to the detection platform, enabling subsequent Raman probe detection of microplastic particles. The detection platform is mounted on a three-dimensional motion platform located within the detection chamber, allowing for convenient and precise adjustments to its position in the X, Y, and Z directions.By coating the center of the upper surface of the detection platform with a superhydrophobic SERS substrate, the Raman spectral signal generated when microplastic particles are irradiated by a laser can be significantly enhanced, thereby improving detection accuracy. An internal heating plate facilitates rapid evaporation of moisture from the sample through heating, allowing microplastic particles to accumulate in the central region of the superhydrophobic SERS substrate, further ensuring the sensitivity and signal-to-noise ratio of the SERS spectral signal. The Raman probe is connected to the laser via a laser emitting fiber and to the Raman spectrometer via a laser receiving fiber. This allows for convenient reception of the laser beam emitted by the laser and its application to the microplastic particles at the accumulation point, while simultaneously acquiring and transmitting the generated Raman scattering spectral signal to the Raman spectrometer.

[0052] Compared to traditional methods, this system dynamically adjusts the sample injection volume using a flow sensor, ensuring the representativeness of the water sample. It also utilizes density gradient flotation technology, combined with a transverse baffle to dynamically adjust the separation zone, and a microporous filter membrane to effectively enrich microplastics, reducing impurity interference and improving separation purity. Furthermore, the detection platform employs superhydrophobic SERS technology, leveraging the droplet condensation effect to highly enrich microplastic particles, significantly enhancing the Raman spectral signal and resulting in significantly improved detection sensitivity. This supports long-term environmental monitoring and pollution early warning needs. This system can conveniently and efficiently detect microplastic particles in aquatic environments with high accuracy, providing reliable technical support for the remediation of microplastic pollution in water bodies.

[0053] The present invention also provides an online intelligent monitoring method for microplastics in the water environment, which employs an online intelligent monitoring system for microplastics in the water environment and includes the following steps;

[0054] Step 1: Fill the sodium chloride solution chamber 9 with saturated sodium chloride solution, and then place the online intelligent monitoring system for microplastics in the water environment near the water body to be tested;

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

[0056] Step 3: Insert the automatic sampling head 1 into the water environment and start its operation via the control unit. The water sample is transported to the pretreatment chamber 3 through the sampling pipeline 27. Simultaneously, the flow rate signal of the sample is collected in real time using the flow sensor 35, and the physical and chemical signals of the sample are collected in real time using the environmental sensor 2. The flow rate signal, physical and chemical signals are sent to the control unit in real time. The control unit obtains the sample flow rate data based on the flow rate signal and the sample temperature and pH value data based on the physical and chemical signals. When the sample flow rate reaches the set flow rate sampling threshold, the automatic sampling head 1 is controlled to stop the sampling operation.

[0057] Step 4: In the pretreatment chamber 3, the water sample is filtered step by step using multiple layered filter membranes in the filter membrane group 4 to remove non-target pollutants and large-diameter particles, leaving only particles smaller than the target size in the water sample to ensure the accuracy of subsequent detection. Then, the filtered water sample is guided to the separation chamber 5 through the connecting pipe 28 to enter the subsequent separation process.

[0058] Step 5: In separation chamber 5, the microplastics in the water sample are quickly and effectively separated from other particles by density flotation using a pre-filled saturated sodium chloride solution. After separation, the lighter microplastic particles are enriched in the upper layer of the liquid, while the heavier particles, such as sand and mineral particles, settle in the lower layer. The baffle drive mechanism 7 is activated to drive the transverse baffle 6 to move slowly to the left in the transverse direction to prevent water flow turbulence and avoid microplastic particles being stirred to the bottom due to turbulence, until 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, 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, so as to provide negative pressure for the filtration of the water sample, and use the microporous filter membrane 14 to separate and filter the microplastics, and obtain a high concentration of microplastic suspension after separation and filtration.

[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 transverse sliding track. Then, control the three-dimensional motion platform 17 to move in the Y and Z directions until the detection platform 39 is located at the set distance directly below the liquid outlet bend 39. Then, control the fourth liquid pump 15 to start working, and deliver 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 bend 39.

[0061] Step 8: First, start the heating plate in the detection platform 16 to heat the microplastic suspension on the superhydrophobic SERS substrate to promote evaporation. During evaporation, the condensation effect of the superhydrophobic SERS substrate causes 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 in a smaller area, the detection accuracy can be improved, and the sensitivity of the SERS spectral signal can be enhanced. Then, control the three-dimensional motion platform 17 to move in the X, Y, and Z directions until the detection platform 16 moves to a set distance directly below the Raman probe 18. This ensures that the Raman probe 18 can be aligned with the formed high-concentration enrichment point.

[0062] Step 9: Control the laser 20 to start working, and emit irradiation laser light to the microplastic particles in the high-concentration enrichment point through the laser emitting fiber 19. The excited microplastic particles generate Raman scattering spectral signals. At the same time, the Raman scattering spectral signals generated on the surface of the microplastic particles are enhanced by the superhydrophobic SERS substrate to form SERS Raman scattering spectral signals. Meanwhile, the SERS Raman scattering spectral signals are received through the laser receiving fiber 25 and transmitted to the Raman spectrometer 26. During this process, the focus of the Raman probe 18 can be adjusted by automatic focusing, thereby optimizing the signal acquisition quality.

[0063] The Raman spectrometer 26 obtains SERS Raman spectral data based on SERS Raman scattering spectral signals, and uses a background subtraction algorithm to remove interference signals from the solvent and substrate. At the same time, noise filtering is used to optimize spectral quality to improve data stability. Principal component analysis and machine learning algorithms are used to automatically match spectral features, and then compare them with massive sample data in the microplastic database to determine the types of microplastics. In addition, the spectral curve is calibrated by combining the SERS Raman scattering spectral signal intensity, and the concentration of microplastics is calculated using the Raman peak integral area.

[0064] As a preferred option, the microplastics database can be set up in the data storage module.

[0065] In order to enable the cleaning of the detection platform and facilitate continuous long-term detection operations, in step eight, after the Raman spectroscopy detection 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 transverse sliding track through the transverse passage 38. Then, the three-dimensional motion platform 17 is controlled to move in the Y and Z directions until the detection platform 16 moves directly below the cleaning mechanism 24 and comes into contact with it. Then, the cleaning drive mechanism 23 is started to drive the cleaning mechanism 24 to rotate through the motion linkage 22 to clean the upper surface of the detection platform 16. After the cleaning is completed, the three-dimensional motion platform 17 is controlled to move so that the detection platform 16 returns to directly below the liquid outlet bend 39 in the detection area 36.

[0066] As a preferred option, when multi-cycle testing is required, steps two through eight can be repeated multiple times.

[0067] As a preferred method, in step four, when it is necessary to discharge heavy particles and impurities deposited at the bottom of the separation chamber 5, the baffle drive mechanism 7 is first activated to drive the transverse baffle 6 to move slowly laterally until the separation chamber 5 is divided into an upper chamber and a lower chamber. Then, the electronic valve 8 is activated to open the chamber outlet B, discharging the heavy particles and impurities at the bottom through the drain pipe A29. After discharge, the electronic valve 8 is closed. Then, the first liquid pump 10 is activated for a set time to add saturated sodium chloride solution to the separation chamber 5 until the set capacity is reached, at which point the first liquid pump 10 is stopped. By periodically discharging the deposited heavy particles and impurities, interference with the microplastic enrichment process can be effectively prevented, which is beneficial to improving detection accuracy. At the same time, the replenishment of saturated sodium chloride solution helps maintain the density flotation environment within the separation chamber, thereby ensuring that microplastic particles can be stably suspended in the upper water layer.

[0068] To address the limitations of existing microplastic detection technologies, this invention provides an automated intelligent detection method for microplastics in aquatic environments based on membrane filtration, superhydrophobic enrichment, and surface-enhanced Raman spectroscopy (SERS). Specifically, during sampling, the sample injection volume can be dynamically adjusted using feedback signals from a flow sensor, facilitating quantitative sampling. A multi-layered filter structure is used to filter the water sample, efficiently removing large particulate pollutants and non-target plastic particles while retaining only the target microplastic particles. A certain amount of saturated sodium chloride solution is first injected into the separation chamber, and then the filtered sample is guided into the separation chamber. Density gradient flotation technology can be used to enrich microplastics in the upper layer of the liquid. Combined with a transverse baffle dynamically adjusting the separation area, a water sample containing microplastic particles can be obtained based on density separation. Microporous membrane filtration technology is then used in the enrichment chamber to achieve preliminary enrichment of microplastics. The pre-enriched high-concentration microplastic suspension is then droplet-added onto the detection platform, where the microplastic particles are further concentrated via a superhydrophobic surface. Simultaneously, heating is used to evaporate the water, resulting in high-concentration enrichment points and significantly enhancing detection sensitivity. By combining this method with SERS technology, high-sensitivity detection of microplastics can be achieved under low-concentration conditions while preserving their chemical fingerprint information.

[0069] This method integrates automatic sampling, density gradient separation, dynamic adjustment of the separation region by transverse baffles, enrichment and concentration, superhydrophobic SERS detection, and intelligent analysis of detection data. It enables fully automated detection of microplastic particles in aquatic environments, requiring no manual intervention. This reduces human error and improves detection efficiency and long-term stability, meeting the need for rapid, accurate, and efficient detection of microplastics in aquatic environments. The method is simple to implement and highly intelligent, providing 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 the water environment, comprising a sampling and pretreatment unit, characterized in that, It also includes a microplastic detection and analysis unit and an enrichment and concentration unit; The sampling and pretreatment unit includes a pretreatment chamber (3), an automatic sampling head (1), a flow sensor (35), an environmental sensor (2), a filter membrane assembly (4), a separation chamber (5), an electronic valve (8), a transverse partition (6), a partition drive mechanism (7), a sodium chloride solution chamber (9), and a first liquid pump (10); the pretreatment chamber (3) has a chamber inlet A and a chamber outlet A at its top and bottom, respectively, and a sampling pipeline (27) is connected at the chamber inlet A; the automatic sampling head (1) is installed on The sampling pipeline (27) is located at its inlet end; the flow sensor (35) is installed at the inlet 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 laterally in the middle section of the pretreatment chamber (3), and the filter membrane group (4) is composed of multiple layered filter membranes distributed sequentially from top to bottom, and the filter pores of the multiple layered filter membranes gradually decrease from top to bottom; the separation chamber (5) is located below the pretreatment chamber (3), and its top and bottom are respectively provided with chamber inlets B. The chamber outlet B has a filling port at the bottom of one side and an overflow port A at the top of the other side. The chamber inlet B is connected to the chamber outlet A via a connecting pipe (28). The chamber outlet B is connected to a drain pipe A (29). The filling port is connected to a filling pipe (30). The overflow port A is connected to an overflow pipe A (31). A partition groove is laterally provided 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 groove and is fully... After sliding into the separation chamber (5), the separation chamber (5) is divided into an upper chamber and a lower chamber; the partition drive 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 move back and forth in the transverse direction; the sodium chloride solution chamber (9) is located on one side outside the separation chamber (5), and its bottom is provided with a drain port, which is connected to the inlet end of the filling pipeline (30) through the drain port; the first liquid pump (10) is connected in series on the filling pipeline (30); 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 located on the right side of the partition chamber (5), and a detection area (36) is provided on the left side of its interior. A detection channel connecting to the detection area (36) is opened on the left side of its interior, and a probe mounting hole is opened in the center area of ​​the detection area (36) on its upper side. The laser (20) and the Raman spectrometer (26) are both located on the outside of the detection chamber (21). The three-dimensional motion platform (17) is installed on the bottom side inside 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 connected to the laser (20) through a laser emitting fiber (19). At the same time, it is connected to the Raman spectrometer (26) through a laser receiving fiber (25). 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). It has a chamber inlet C and a chamber outlet C at its top and bottom, respectively. An overflow port B is provided on the upper part of one side of the chamber. The chamber inlet C is connected to the liquid outlet end of the overflow pipe A (31). The chamber outlet C is connected to the drain pipe B (32). The overflow port B is connected to the drain pipe B (32). An overflow pipe B (33) is connected, and the outlet end of the overflow pipe 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 pipe A (31); the third liquid pump (13) is connected in series to the drain pipe B (32); the fourth liquid pump (15) is connected in series to the overflow pipe B (33); The microplastic detection and analysis unit also includes a vertical partition (34), a motion linkage (22), a cleaning mechanism (24), and a cleaning drive mechanism (23). The right side of the detection chamber (21) is provided with a cleaning area (37), and a cleaning channel is provided on the right side of the cleaning area (37); 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 and right spaces of the vertical partition (34); the lower end of the vertical partition (34) is left with a set distance from the bottom plate of the detection chamber (21) and forms a transverse passage (38); a transverse sliding track is installed on the bottom plate inside the detection chamber (21); the three-dimensional motion platform (17) is installed on the transverse sliding track; The motion 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 motion link (22); the cleaning drive mechanism (23) is located outside the detection chamber (21) and its output end is connected to the right end of the motion link (22); The detection platform (16) is made of low fluorescence background material, and its upper surface center is coated with a superhydrophobic SERS substrate, and a heating plate is installed inside it. It also includes a control unit, which is connected to a flow sensor (35), an environmental 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.

2. The online intelligent monitoring system for microplastics in the water environment according to claim 1, characterized in that, The inner surface of the enrichment chamber (12) is coated with a superhydrophobic coating; the microporous filter membrane (14) is made of a nano-reinforced composite membrane.

3. The online intelligent monitoring system for microplastics in the water environment according to claim 1, characterized in that, A baffle plate is provided at the chamber entrance C of the enrichment chamber (12).

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

5. A method for online intelligent monitoring of microplastics in the water environment, employing an online intelligent monitoring system for microplastics in the water environment as described in any one of claims 1 to 4, characterized in that, Includes the following steps; Step 1: Fill the sodium chloride solution chamber (9) with saturated sodium chloride solution, and then place the online intelligent monitoring system for microplastics in the water environment near the water body to be tested; Step 2: Control the first liquid pump (10) to start working through the control unit, and use the first liquid pump (10) to add saturated sodium chloride solution into the separation chamber (5) until the set capacity is reached, and then stop the first liquid pump (10) from working. 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). At the same time, use the flow sensor (35) to collect the flow signal of the sample in real time, and use the environmental sensor (2) to collect the physical and chemical signals of the sample in real time. 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 based on the flow signal, and obtains the temperature data and pH value data of the sample based on the physical and chemical signals. When the flow rate of the sample reaches the set flow sampling threshold, control the automatic sampling head (1) to stop the sampling operation. Step 4: In the pretreatment chamber (3), the water sample is filtered step by step using multiple layered filter membranes in the filter membrane group (4) to remove non-target pollutants and large-diameter particles, leaving only particles smaller than the target size in the water sample. Then, the filtered water sample is guided to the separation chamber (5) using the connecting pipe (28). Step 5: In the separation chamber (5), the microplastics in the water sample are quickly and effectively separated from other particles by density flotation using a pre-filled saturated sodium chloride solution. After separation, the lighter microplastic particles are enriched in the upper layer of the liquid, while the heavier particles settle in the lower layer of the liquid. The control baffle drive mechanism (7) is started to drive the transverse baffle (6) to move slowly to the left in the transverse direction until the separation chamber (5) is divided 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, so as to provide negative pressure for the filtration of the water sample, and use the microporous filter membrane (14) to separate and filter the microplastics, and obtain a high concentration of microplastic suspension after separation and filtration. 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 transverse sliding track. Then, control the three-dimensional motion platform (17) to move in the Y and Z directions until the detection platform (16) is located at the set distance directly below the liquid outlet bend (39). Then, control the fourth liquid pump (15) to start working and 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 bend (39). Step 8: 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, the microplastic particles are aggregated towards the central minimum contact area by utilizing the condensation effect of the superhydrophobic SERS substrate, forming a high concentration enrichment point in the center of the superhydrophobic SERS substrate. Then, control the three-dimensional motion platform (17) to move in the X, Y and Z directions until the detection platform (16) moves to a set distance directly below the Raman probe (18). Step 9: Control the laser (20) to start working, and emit irradiation laser to the microplastic particles in the high concentration enrichment point through the laser emitting fiber (19). At the same time, the Raman scattering spectrum signal generated on the surface of the microplastic particles is enhanced by the superhydrophobic SERS substrate to form a SERS Raman scattering spectrum signal. Meanwhile, the SERS Raman scattering spectrum signal is received through the laser receiving fiber (25) and transmitted to the Raman spectrometer (26). The Raman spectrometer (26) obtains SERS Raman spectral data based on SERS Raman scattering spectral signals, and uses a background subtraction algorithm to remove interference signals from the solvent and substrate. At the same time, noise filtering is used to optimize the spectral quality, and spectral features are automatically matched through principal component analysis and machine learning algorithms. The data is then compared with massive sample data in the microplastic database to determine the types of microplastics. In addition, the spectral curve is calibrated by combining the SERS Raman scattering spectral signal intensity, and the concentration of microplastics is calculated using the Raman peak integral area.

6. The online intelligent monitoring method for microplastics in the water environment according to claim 5, characterized in that, In step eight, after the Raman spectroscopy detection 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 transverse sliding track through the transverse passage (38). Then, the three-dimensional motion platform (17) is controlled to move in the Y and Z directions until the detection platform (16) moves directly below the cleaning mechanism (24) and comes into contact with 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 link (22) to clean the upper surface of the detection platform (16).

7. The online intelligent monitoring method for microplastics in the water environment according to claim 6, characterized in that, 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 baffle drive mechanism (7) to start working, drive the transverse baffle (6) to move slowly in the transverse direction until the separation chamber (5) is divided into an upper chamber and a lower chamber. Then control the electronic valve (8) to open the chamber outlet B, and discharge the heavy particles and impurities at the bottom through the drain pipe A (29). 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 add saturated sodium chloride solution into the separation chamber (5) until the set capacity is reached, and then stop the first liquid pump (10).

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