Online monitoring method and system for trace zinc ions in aqueous solution

Abstract

This invention relates to the field of analytical detection technology, and in particular to an online monitoring method and system for trace zinc ions in aqueous solutions. The sampling and processing module filters the input aqueous solution to be tested and performs total organic carbon (TOC) detection on the filtered solution at a preset wavelength. Based on the TOC detection results, the filtered aqueous solution is digested and then transported to an enrichment module, or the filtered aqueous solution is transported to the enrichment module. The enrichment module enriches the input aqueous solution for trace zinc ions, and the desorbed solution is then transported to a trace zinc ion detection module for detection. This method solves the problems of low sensitivity, complex operation, and low detection efficiency of traditional detection methods. It is suitable for intelligent and automated monitoring of surface water, drinking water, and aqueous solutions in specific application scenarios, and features high sensitivity, high automation, strong anti-interference ability, and low operating cost.

Description

Technical Field

[0001] This invention relates to the field of analytical detection technology, and in particular to an online monitoring method and system for trace zinc ions in aqueous solutions. Background Technology

[0002] In industrial production (such as electronics and nuclear power), there is an increasing demand for the detection of trace zinc in aqueous solutions. While zinc concentrations are low in aqueous solutions from surface water, groundwater, drinking water, and specific industrial processes, the sensitivity requirements for zinc detection methods in aqueous solutions are becoming increasingly stringent.

[0003] Currently, the main methods for detecting zinc in aqueous solutions include chemical analysis, spectrometry, mass spectrometry, electrochemistry, and biochemistry. Chemical analysis primarily involves titration, which requires manual intervention and is difficult to automate. Spectrometry mainly includes colorimetry and atomic absorption spectrometry. Colorimetry is low-cost but has low sensitivity and requires strict pH control; atomic absorption spectrometry has high sensitivity but is expensive and lacks real-time performance. Mass spectrometry has high sensitivity and stability but is limited by high cost, operational complexity, and demanding installation and maintenance requirements. Electrochemical methods commonly use anodic stripping voltammetry (ASV) and potentiometric titration; ASV has high sensitivity but poor interference resistance and electrode stability; potentiometric titration has a high degree of automation but low sensitivity and slow dynamic response. Biochemical methods mainly include enzyme inhibition and immunoassay, which are not yet used in online detection.

[0004] In summary, existing technologies generally suffer from bottlenecks such as weak anti-interference capabilities, insufficient adaptability to harsh environments, high maintenance costs, and a contradiction between sensitivity and real-time performance. Summary of the Invention

[0005] Therefore, the purpose of this invention is to provide an online monitoring system and method for trace zinc ions in aqueous solutions. This system solves the problems of low sensitivity, complex operation, and low detection efficiency of traditional detection methods. It is suitable for intelligent and automated monitoring of surface water, drinking water, and aqueous solutions in specific application scenarios, and features high sensitivity, high automation, strong anti-interference ability, and low operating cost. The technical solution is as follows:

[0006] In a first aspect, this application discloses an online monitoring system for trace zinc ions in aqueous solution, comprising: a sampling and processing module 1, an enrichment module 2, a trace zinc ion detection module 3, and a main control module 4;

[0007] The sampling processing module 1 is connected to the enrichment module 2. The sampling processing module 1 is used to filter the aqueous solution to be tested and to detect the total organic carbon in the filtered aqueous solution. When the total organic carbon value is less than or equal to the preset total organic carbon threshold, the filtered aqueous solution to be tested is input to the enrichment module 2. When the total organic carbon value is greater than the total organic carbon threshold, the aqueous solution to be tested is digested and then input to the enrichment module 2.

[0008] The enrichment module 2 is connected to the trace zinc ion detection module 3. The enrichment module 2 is used to enrich trace zinc ions in the input test aqueous solution and to transport the enriched test aqueous solution to the trace zinc ion detection module 3.

[0009] The trace zinc ion detection module 3 is used to detect trace zinc ions in the enriched aqueous solution of the test;

[0010] The main control module 4 is connected to the sampling and processing module 1, the enrichment module 2, and the trace zinc ion detection module 3. The main control module 4 is used to receive the total organic carbon detection result detected by the sampling and processing module 1, and based on the total organic carbon detection result, control the sampling and processing module 1 to digest the test aqueous solution or to transport the test aqueous solution to the enrichment module 2. The main control module 4 is used to control the enrichment module 2 to transport the enriched and desorbed test aqueous solution to the trace zinc ion detection module 3 when the test aqueous solution meets the detection conditions. The main control module 4 is used to control the trace zinc ion detection module 3 to perform detection.

[0011] In this embodiment, the solution is automatically injected through intelligent control, pretreated, and then automatically enriched through an enrichment column. After enrichment, it enters the detection device for automatic online detection. This solves the problems of low sensitivity, complex operation, and low detection efficiency of traditional detection methods, and realizes automated monitoring. It has the technical effects of high sensitivity, high degree of automation, strong anti-interference ability, and low operating cost.

[0012] In one embodiment, the sampling and processing module 1 includes a sample sampling unit 11, a total organic carbon detection unit 12, a digestion unit 13, and a digesting agent injection unit 14;

[0013] The sample sampling unit 11 is connected to the total organic carbon detection unit 12. The sample sampling unit 11 is used to filter the aqueous solution to be tested and then transmit it to the total organic carbon detection unit 12.

[0014] The total organic carbon detection unit 12 is connected to the digestion unit 13 and the enrichment module 2 via the first flow path control valve 51. The digestion unit 13 is connected to the enrichment module 2. The total organic carbon detection unit 12 is used to detect the total organic carbon in the filtered test aqueous solution. When the total organic carbon value is less than or equal to the preset total organic carbon threshold, the filtered test aqueous solution is input to the enrichment module 2. When the total organic carbon value is greater than the total organic carbon threshold, the test aqueous solution is digested by the digestion unit 13 and then input to the enrichment module 2. The digesting agent injection unit 14 is connected to the digestion unit 13 via the second flow path control valve 52.

[0015] The main control module 4 is connected to the total organic carbon detection unit 12. The main control module 4 is used to receive the total organic carbon detection signal sent by the total organic carbon detection unit 12, and control the switching of the first flow path control valve 51 and the opening and closing of the second flow path control valve 52 according to the total organic carbon detection signal.

[0016] In this embodiment, the filtered aqueous solution to be tested is digested based on the total organic carbon detection result to eliminate the interference of organic matter during trace zinc ion detection.

[0017] In one embodiment, the sample sampling unit 11 includes a filter assembly 111, a first injection pump 112, and a differential pressure sensor 113;

[0018] The filter assembly 111 is connected to the total organic carbon detection unit 12 via the first injection pump 112; the first injection pump 112 is connected to the main control module 4 and is used to receive the control signal of the main control module 4 and transmit the filtered test solution to the total organic carbon detection unit 12.

[0019] The two detection probes of the differential pressure sensor 113 are respectively set on the front and rear sides of the filter membrane 114 of the filter assembly 111; the differential pressure sensor 113 is connected to the main control module 4, and the differential pressure sensor 113 is used to detect the pressure difference of the test aqueous solution before and after passing through the filter assembly 111, and generate a differential pressure detection signal to be sent to the main control module 4; when the differential pressure value obtained by the differential pressure detection signal is greater than the preset differential pressure threshold, the main control module 4 prompts to replace the filter assembly.

[0020] In one embodiment, the digestion unit 13 includes a heat exchange device 131, a digestion device 132, and a first peristaltic pump 133; the heat exchange device 131 includes a first heat exchange tube 131a and a second heat exchange tube 131b, the second heat exchange tube 131b being wound around the outer wall of the first heat exchange tube 131a.

[0021] One end of the first heat exchange tube 131a is connected to the total organic carbon detection unit 12 through the first flow path control valve 51, and the other end of the first heat exchange tube 131a is connected to the liquid inlet of the digestion device 132; one end of the second heat exchange tube 131b is connected to the liquid outlet of the digestion device 132, and the other end of the second heat exchange tube 131b is connected to the enrichment module 2 through the first peristaltic pump 133.

[0022] In this embodiment of the application, the first heat exchange tube 131a in the heat exchange device 132 is used to preheat the sample liquid, and the second heat exchange tube 131b is used to cool the high-temperature liquid after digestion, so that the cooled and filtered digested aqueous solution to be tested enters the enrichment module 2 through the first flow path control valve 51.

[0023] In one embodiment, the enrichment module 2 includes a balance adjustment unit 21, an enrichment unit 22, and a desorbent injection unit 23;

[0024] The balance adjustment unit 21 is connected to the enrichment unit 22 through the third flow path control valve 53; the balance adjustment unit 21 is used to balance the aqueous solution to be tested after filtration and digestion before inputting it into the enrichment unit 22.

[0025] The enrichment unit 22 is connected to the trace zinc ion detection module 3 through the fourth flow path control valve 54. The enrichment unit 22 is used to enrich and desorb zinc ions in the digested test aqueous solution, and input the desorbed test aqueous solution into the trace zinc ion detection module 3. The desorbent injection unit 23 is connected to the enrichment unit 22 through the third flow path control valve 53.

[0026] The main control module 4 is connected to the balance adjustment unit 21 and the enrichment unit 22. The main control module 4 is used to receive a first signal sent by the balance adjustment unit 21 and, based on the first signal, control the switching of the flow path of the third flow path control valve 53. The main control module 4 is also used to receive a second signal sent by the enrichment unit 22 and, based on the second signal, control the switching of the flow path of the third flow path control valve 53. The main control module 4 is also used to receive a third signal sent by the enrichment unit 22 and, based on the third signal, control the switching of the flow path of the fourth flow path control valve 54. The first signal is used to instruct the balance adjustment unit 21 to complete the balance adjustment operation; the second signal is used to instruct the enrichment unit 22 to complete the enrichment operation; and the third signal is used to instruct the enrichment unit 22 to complete the digestion operation.

[0027] In this embodiment of the application, the balance adjustment unit 21 adjusts the pH value of the filtered and digested aqueous solution to reduce the negative impact of the pH value of the aqueous solution after digestion by the digesting agent on the enrichment process of the enrichment unit 22, thereby reducing the enrichment rate.

[0028] In one embodiment, the enrichment unit 22 includes a pressure sensor 221, a first enrichment column 222, a second check valve 223, a second enrichment column 224, and a third check valve 225.

[0029] One end of the pressure sensor 221 is connected to the balance adjustment unit 21 through the third flow path control valve 53; the other end of the pressure sensor 221 is connected to one end of the first enrichment column 222, and the other end of the pressure sensor 221 is connected to one end of the second enrichment column 224 through the fifth flow path control valve 55; the other end of the first enrichment column 222 is connected to the trace zinc ion detection module 3 through the second one-way valve 223 and the fourth flow path control valve 54 in sequence; the other end of the second enrichment column 224 is connected to the trace zinc ion detection module 3 through the third one-way valve 225 and the fifth flow path control valve 55 in sequence.

[0030] Pressure sensor 221 detects the flow path pressure in enrichment unit 22 and sends the generated pressure detection signal to main control module 4. Main control module 4 analyzes the received pressure detection signal. When the flow path pressure is less than or equal to a preset flow path pressure threshold, main control module 4 controls the fifth flow path control valve 55 to close, and inputs the digested aqueous solution to be tested into the first enrichment column 222 for enrichment and desorption. When the flow path pressure is greater than the flow path pressure threshold, main control module 4 controls the fifth flow path control valve 55 to open, and inputs the digested aqueous solution to be tested into the first enrichment column 222 and the second enrichment column 224 respectively for enrichment and desorption.

[0031] In this embodiment, the sample injection is controlled by both pressure and volume, which effectively reduces system resistance. Furthermore, the single and dual column flow paths can be dynamically switched automatically through pressure feedback to meet the flow rate requirements for different enrichment factors of trace zinc ions in the solution, thereby improving enrichment efficiency and system precision.

[0032] In one embodiment, the system further includes a trace zinc ion detection module 3 comprising a pH adjustment unit 31 and a trace zinc ion detection unit 32.

[0033] pH adjustment unit 31 is connected to enrichment module 2 through fourth flow path control valve 54; pH adjustment unit 31 is connected to trace zinc ion detection unit 32; pH adjustment unit 31 is used to adjust the pH of the desorbed aqueous solution to be tested and input it to trace zinc ion detection unit 32 for zinc ion detection.

[0034] The pH adjustment unit 31 includes a second valve-generating device 311 and a fifth injection pump 312; one end of the fifth injection pump 312 is connected to the second valve-generating device 311, and the other end of the fifth injection pump 312 is connected to the trace zinc ion detection unit 32; the main control module 4 controls the second valve-generating device 311 to release buffer solution to adjust the pH value of the desorbed test aqueous solution input to the second valve-generating device 311; the main control module 4 is used to control the fifth injection pump 312 to input the pH-adjusted test aqueous solution to the trace zinc ion detection unit 32.

[0035] In this embodiment, since different zinc ion detection methods have different pH requirements, corresponding buffer solutions are released according to different zinc ion detection methods to adjust the pH value of the desorbed test aqueous solution input to the generator 311 on the second valve, so as to meet the pH requirements of the zinc ion detection method in a specific application scenario and improve the accuracy of zinc ion detection.

[0036] In one embodiment, the system further includes a waste liquid collection unit 6; the waste liquid collection unit 6 includes a waste liquid collection device 61, a fourth check valve 62, and a second peristaltic pump 63;

[0037] One inlet of the waste liquid collection device 61 is connected to the enrichment unit 22 through the fourth flow path control valve 54; the other inlet of the waste liquid collection device 61 is connected to the trace zinc ion detection unit 32 through the fourth one-way valve 62 and the second peristaltic pump 63 in sequence; the main control module 4 is used to control the switching of the fourth flow path control valve 54.

[0038] In this embodiment, by setting up a waste liquid collection device 61, the enrichment unit 22 can input the aqueous solution from the first enrichment column 222 and the second enrichment column 224 into the waste liquid collection device 61 through the fourth flow path control valve 52. This allows the test aqueous solution with a significantly reduced zinc ion content after the enrichment operation to leave the first enrichment column 222 and the second enrichment column 224, enabling the test aqueous solution with a higher zinc ion content to be input from the balance adjustment unit 21 into the first enrichment column 222 and the second enrichment column 224, thereby improving the enrichment efficiency. Furthermore, after the trace zinc ion detection unit 32 completes the trace zinc ion detection, the liquid after trace zinc ion detection is sequentially input into the waste liquid collection device 61 through the second peristaltic pump 62 and the fourth one-way valve 63 to maintain the accuracy of trace zinc ion detection.

[0039] In one embodiment, the system further includes a cleaning agent injection unit 7; the cleaning agent injection unit 7 includes a cleaning agent storage device 71, a sixth injection pump 72, a fifth check valve 73, a seventh injection pump 74, and a sixth check valve 75.

[0040] One end of the sixth injection pump 72 is connected to the cleaning agent storage device 71, and the other end of the sixth injection pump 72 is connected to the enrichment unit 22 through the fifth one-way valve 73 and the third flow path control valve 53 in sequence; one end of the seventh injection pump 74 is connected to the cleaning agent storage device 71, and the other end of the seventh injection pump 74 is connected to the pH adjustment unit 31 through the sixth one-way valve 75 and the three-way valve 33 in sequence.

[0041] The main control module 4 is used to respond to the system cleaning signal, control the sixth injection pump 72 to input the cleaning agent in the cleaning agent storage device 71 into the enrichment unit 22 through the fifth one-way valve 73 and the third flow path control valve 53, and control the seventh injection pump 74 to input the cleaning agent in the cleaning agent storage device 71 into the pH adjustment unit 31 through the sixth one-way valve 75.

[0042] In this embodiment, after the trace zinc ion detection is completed, the main control module 4 sends a corresponding control signal to the sixth injection pump 72 and the seventh injection pump 74, controlling the sixth injection pump 72 and the seventh injection pump 74 to start working. The sixth injection pump 72 drives the cleaning solution stored in the cleaning agent storage device 71 to flow at a rate of 10 mL / min through the fifth one-way valve 73 and the first flow path control valve 51 to the enrichment unit 22 to clean the enrichment unit 22, ensuring that the first enrichment column 222 and the second enrichment column 224 in the enrichment unit 22 are rinsed to neutral, ensuring the regeneration and reusability of the enrichment unit 22. The seventh injection pump 74 drives the cleaning solution stored in the cleaning agent storage device 71 to flow through the sixth one-way valve 75 to the pH adjustment unit 31 to clean the pH adjustment unit 31.

[0043] Secondly, this application discloses an online monitoring method for trace zinc ions using an online monitoring system for trace zinc ions in aqueous solution as described in the first aspect, comprising the following steps:

[0044] The sampling and processing module 1 filters the input aqueous solution to be tested, and performs total organic carbon detection and signal generation on the filtered aqueous solution at a preset wavelength to obtain the total organic carbon detection signal and send it to the main control module 4.

[0045] The main control module 4 analyzes the obtained total organic carbon detection signal to obtain the total organic carbon value; when the total organic carbon value is less than or equal to the preset total organic carbon threshold, the main control module 4 controls the sampling and processing module 1 to transport the filtered test aqueous solution to the enrichment module 2; when the total organic carbon value is greater than the total organic carbon threshold, the main control module 4 controls the sampling and processing module 1 to digest the filtered test aqueous solution and transport the digested test aqueous solution to the enrichment module 2.

[0046] The enrichment module 2 enriches trace zinc ions in the input aqueous solution to be tested. The main control module 4 controls the enrichment module 2 and, when the aqueous solution to be tested meets the detection conditions, delivers the enriched and desorbed aqueous solution to the trace zinc ion detection module 3. The main control module 4 controls the trace zinc ion detection module 3 to detect trace zinc ions.

[0047] This application provides an online monitoring system and method for trace zinc ions in aqueous solutions, which solves the problems of low sensitivity, complex operation, and low detection efficiency of traditional detection methods. It is suitable for intelligent and automated monitoring of surface water, drinking water, and aqueous solutions in specific application scenarios, and features high sensitivity, high degree of automation, strong anti-interference ability, and low operating cost.

[0048] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0049] Figure 1 A schematic diagram of the structure of an online monitoring system for trace zinc ions in aqueous solution provided in one embodiment of this application;

[0050] Figure 2 A schematic diagram of the structure of an online monitoring system for trace zinc ions in aqueous solution provided in another embodiment of this application;

[0051] Figure 3 This is a schematic flowchart illustrating an online monitoring method for trace zinc ions in an online monitoring system for trace zinc ions in aqueous solution, provided as an embodiment of this application. Detailed Implementation

[0052] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0053] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0054] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0055] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of an online monitoring system for trace zinc ions in an aqueous solution provided in one embodiment of this application.

[0056] In this embodiment of the application, the online monitoring system for trace zinc ions in aqueous solution includes: a sampling and processing module 1, an enrichment module 2, a trace zinc ion detection module 3, and a main control module 4.

[0057] The sampling processing module 1 is connected to the enrichment module 2. The sampling processing module 1 is used to filter the aqueous solution to be tested and to detect the total organic carbon in the filtered aqueous solution. When the total organic carbon value is less than or equal to the preset total organic carbon threshold, the filtered aqueous solution to be tested is input to the enrichment module 2. When the total organic carbon value is greater than the total organic carbon threshold, the aqueous solution to be tested is digested and then input to the enrichment module 2.

[0058] The enrichment module 2 is connected to the trace zinc ion detection module 3. The enrichment module 2 is used to enrich the input test aqueous solution with trace zinc ions and to transport the enriched test aqueous solution to the trace zinc ion detection module 3.

[0059] The trace zinc ion detection module 3 is used to detect trace zinc ions in the enriched aqueous solution.

[0060] The main control module 4 is connected to the sampling and processing module 1, the enrichment module 2, and the trace zinc ion detection module 3. The main control module 4 is used to receive the total organic carbon detection result detected by the sampling and processing module 1, and based on the total organic carbon detection result, control the sampling and processing module 1 to digest the test aqueous solution or to transport the test aqueous solution to the enrichment module 2. The main control module 4 is used to control the enrichment module 2 to transport the enriched and desorbed test aqueous solution to the trace zinc ion detection module 3 when the test aqueous solution meets the detection conditions. The main control module 4 is used to control the trace zinc ion detection module 3 to perform detection.

[0061] Specifically, the main control module 4 is a microcontroller or microcontroller chip used for receiving, transmitting, and parsing signals. The main control module 4 receives the total organic carbon (TOC) detection signal sent by the sampling and processing module 1, parses the TOC detection signal to obtain the TOC detection result, and generates a corresponding control signal based on the TOC detection result to control the sampling and processing module 1 to digest the test aqueous solution or to transport the test aqueous solution to the enrichment module 2. When the test aqueous solution meets the detection conditions, the main control module 4 controls the enrichment module 2 to transport the enriched and desorbed test aqueous solution to the trace zinc ion detection module 3.

[0062] In this embodiment, when the online monitoring system for trace zinc ions in aqueous solution is working, the sampling and processing module 1 filters the input aqueous solution to be tested. The sampling and processing module 1 performs total organic carbon detection and signal generation on the filtered aqueous solution to be tested, obtains the total organic carbon detection signal, and sends it to the main control module 4 for analysis to obtain the total organic carbon value. When the total organic carbon value is less than or equal to the preset total organic carbon threshold (specifically, the total organic carbon threshold is set to 10 mg / L), the main control module 4 determines that the filtered aqueous solution to be tested meets the enrichment requirements, and the main control module 4 controls the sampling and processing module 1 to input the aqueous solution to be tested into the enrichment module 2. When the total organic carbon value is greater than the total organic carbon threshold, the main control module 4 determines that the filtered aqueous solution to be tested does not meet the enrichment requirements, and the main control module 4 controls the sampling and processing module 1 to digest the aqueous solution to be tested and then input it into the enrichment module 2 to eliminate the interference of organic matter during the detection of trace zinc ions.

[0063] Enrichment module 2 enriches trace zinc ions in the input aqueous solution to be tested. When the aqueous solution to be tested meets the detection conditions, specifically, the detection conditions can be a preset enrichment time to ensure the enrichment effect of zinc ions in the solution, the main control module 4 controls enrichment module 2 to transport the desorbed aqueous solution to be tested after enrichment to trace zinc ion detection module 3. The main control module 4 controls trace zinc ion detection module 3 to perform trace zinc ion detection.

[0064] Please see Figure 1 In one embodiment, the sampling and processing module 1 includes a sample sampling unit 11, a total organic carbon detection unit 12, a digestion unit 13, and a digesting agent injection unit 14.

[0065] The sample sampling unit 11 is connected to the total organic carbon detection unit 12. The sample sampling unit 11 is used to filter the aqueous solution to be tested and then transmit it to the total organic carbon detection unit 12.

[0066] The total organic carbon detection unit 12 is connected to the digestion unit 13 and the enrichment module 2 via the first flow path control valve 51. The digestion unit 13 is connected to the enrichment module 2. The total organic carbon detection unit 12 is used to detect the total organic carbon in the filtered test aqueous solution. When the total organic carbon value is less than or equal to the preset total organic carbon threshold, the filtered test aqueous solution is input to the enrichment module 2. When the total organic carbon value is greater than the total organic carbon threshold, the test aqueous solution is digested by the digestion unit 13 and then input to the enrichment module 2. The digesting agent injection unit 14 is connected to the digestion unit 13 via the second flow path control valve 52.

[0067] The main control module 4 is connected to the total organic carbon detection unit 12. The main control module 4 is used to receive the total organic carbon detection signal sent by the total organic carbon detection unit 12, and control the switching of the first flow path control valve 51 and the opening and closing of the second flow path control valve 52 according to the total organic carbon detection signal.

[0068] Specifically, the sample sampling unit 11 filters the input aqueous solution to be tested, wherein the pH value of the aqueous solution to be tested is between 6 and 9, and is adjusted by using 0.1 mol / L HNO3 and 0.1 mol / L NH3•H2O solutions.

[0069] The total organic carbon (TOC) detection unit 12 employs a visible light spectrophotometer (UV-vis) for initial detection. The TOC detection unit 12 performs TOC detection and signal generation on the filtered aqueous solution at a preset wavelength, specifically 254 nm, for 5 minutes, obtaining a TOC detection signal and sending it to the main control module 4. The main control module 4 analyzes the obtained TOC detection signal to obtain the TOC value. If the TOC value is ≤ 10 mg / L, the main control module 4 controls the first flow path control valve 51 to open the flow path between the TOC detection unit 12 and the enrichment module 2, allowing the TOC detection unit 12 to input the filtered test aqueous solution into the enrichment module 2.

[0070] If the total organic carbon (TOC) value is greater than 10 mg / L, the main control module 4 controls the first flow path control valve 51 to close the flow path between the total organic carbon detection unit 12 and the enrichment module 2, and opens the flow path between the total organic carbon detection unit 12 and the digestion unit 13. The total organic carbon detection unit 12 inputs the filtered test aqueous solution into the digestion unit 13 to eliminate the interference of organic matter during trace zinc ion detection and improve the accuracy of trace zinc ion detection.

[0071] Most natural organic compounds (such as humic acid and fulvic acid) and synthetic organic compounds (such as surfactants and chelating agents) exhibit strong absorption in the 254nm ultraviolet band, while inorganic carbon (such as CO3²⁻ and HCO3⁻) shows no absorption at this wavelength. Choosing 254nm avoids interference from inorganic carbon, specifically capturing only the total amount of organic matter in the water sample, ensuring that the Total Organic Carbon (TOC) value accurately reflects the degree of organic pollution. Moreover, 254nm is in the low-band ultraviolet range, making it sensitive to absorption signals from low concentrations of organic matter. It can accurately distinguish between a TOC value of 5 mg / L and a TOC value of 15 mg / L, providing sufficient signal resolution for determining the 10 mg / L threshold. If a higher wavelength (such as 365nm) is chosen, the absorption intensity of organic matter decreases, and the low TOC signal is easily masked by noise, potentially leading to the failure of the diversion logic.

[0072] Organic matter in water samples may exhibit uneven distribution (e.g., suspended small organic particles). Short-term detection (e.g., 1 minute) may lead to misjudgment of the Total Organic Carbon (TOC) value due to instantaneous sampling deviations (e.g., actual TOC = 8 mg / L, but detected as 12 mg / L due to instantaneous particle interference). Continuous detection for 5 minutes can eliminate such fluctuations through signal averaging (e.g., taking the stable average over 5 minutes), ensuring that the TOC value accurately reflects the overall organic matter level of the water sample. Moreover, the trace zinc ion online monitoring in this embodiment requires a rapid response; a 5-minute duration, while ensuring signal stability, will not significantly prolong the pretreatment cycle. If the detection time is too short (e.g., less than 3 minutes), signal stability will be insufficient; if it is too long (e.g., more than 10 minutes), it will reduce overall monitoring efficiency, especially affecting the throughput when analyzing batches of samples.

[0073] Specifically, when the total organic carbon (TOC) value is ≤10 mg / L, the proportion of organic matter forming complexes with zinc ions in the water sample is usually less than 5%, with free Zn²⁺ dominating. Direct entry into the enrichment module allows for efficient capture, and the detection error can be controlled within 5%. However, when the TOC value is >10 mg / L, the proportion of organically bound zinc may rise to over 30%. Without digestion, this would lead to a significant decrease in zinc ion recovery (e.g., from 95% to 60%). The 10 mg / L threshold is a critical point defined based on the "acceptable level of organic interference." Furthermore, to avoid over-digestion and reduce the risk of contamination, digestion processes (such as UV oxidation and microwave digestion) may introduce exogenous contaminants (e.g., trace amounts of zinc dissolved in the digestion tank, impurities in the reagents). Skipping digestion when the TOC value is ≤10 mg / L reduces this type of contamination; only necessary digestion is performed on water samples with high TOC values, minimizing additional errors while controlling interference.

[0074] Overall, the 254nm wavelength is used for 5 minutes of detection, and a 10mg / L threshold is set. These three elements form a complete logical chain, providing a specific and sensitive signal and ensuring reliable detection. For low-pollution water samples (total organic carbon (TOC) ≤ 10mg / L), the sample can quickly pass through the enrichment module, shortening the process, reducing pollution, and ensuring detection efficiency. For high-pollution water samples (TOC > 10mg / L), the sample is forced into the digestion module to completely eliminate organic interference and ensure detection accuracy.

[0075] In this embodiment, the aqueous solution to be tested is automatically injected through intelligent control, pretreated, and then automatically enriched through an enrichment column. After enrichment, it enters the detection device for automatic online detection, which solves the problems of low sensitivity, complex operation, and low detection efficiency of traditional detection methods. It realizes automated monitoring and has the technical effects of high sensitivity, high degree of automation, strong anti-interference ability, and low operating cost.

[0076] In one embodiment, the sample sampling unit 11 includes a filter assembly 111, a first injection pump 112, and a differential pressure sensor 113.

[0077] The filter assembly 111 is connected to the total organic carbon detection unit 12 via the first injection pump 112; the first injection pump 112 is connected to the main control module 4 and is used to receive the control signal of the main control module 4 and transmit the filtered aqueous solution to be tested to the total organic carbon detection unit 12.

[0078] Specifically, the main control module 4 generates a corresponding control signal and sends it to the first injection pump 112, controlling the first injection pump 112 to drive the test aqueous solution into the filter assembly 111 at a rate of 5 ~ 30 mL / min. The test aqueous solution is filtered by the filter membrane in the filter assembly 111 to remove suspended particulate matter. The filtered test aqueous solution is then input to the total organic carbon detection unit 12 to eliminate the interference of suspended particulate matter in the test aqueous solution during total organic carbon detection. The filter screen can be made of materials such as nylon, polyvinylidene fluoride, polyethylene, mixed cellulose, or polyethersulfone, and the pore size of the filter membrane can be 1 ~ 2 μm.

[0079] The adjustable pumping rate of 5–30 mL / min balances filtration efficiency and effectiveness, adapting to different water sample characteristics. Specifically, for low-turbidity water samples (such as surface water and purified industrial wastewater with suspended particulate matter concentrations less than 10 mg / L), a higher rate of 20–30 mL / min can be used to complete the filtration of a sufficient volume of water sample within 1–2 minutes, shortening the pretreatment time and meeting the rapid response requirements of online monitoring. For medium- to high-turbidity water samples (such as untreated industrial wastewater and polluted groundwater with suspended particulate matter concentrations of 10–50 mg / L), the rate can be lowered to 5–15 mL / min. By reducing the flow rate, the accumulation rate of particulate matter on the filter membrane surface is reduced, preventing rapid clogging of the filter membrane pores and ensuring a continuous and stable filtration process. This adjustable speed design adapts to water samples of different turbidity, avoiding clogging or inefficiency, and balancing efficiency and sustainability. Furthermore, trace amounts of zinc ions (typically in the μg / L range) may only have brief contact with the filter membrane surface due to excessively high flow rates (greater than 30 mL / min), resulting in ineffective filtration. Conversely, excessively slow flow rates (less than 5 mL / min) prolong the residence time of the water sample in the filtration unit, increasing the risk of zinc ions being adsorbed by the container walls or the filter membrane. By controlling the contact efficiency within the 5–30 mL / min range, the adsorption loss rate of zinc ions can be kept below 2%, reducing filter membrane adsorption interference and ensuring the recovery rate of the target analyte.

[0080] The 1-2 μm pore size of the filter membrane allows for precise removal of interfering particulate matter, balancing thorough filtration with water sample permeability. Specifically, suspended particulate matter larger than 1 μm in diameter entering the total organic carbon (TOC) detection unit 12 and the enrichment module 2 can cause errors in TOC detection or block the flow paths of these units. The 1-2 μm pore size effectively intercepts these particles while allowing dissolved substances to pass through smoothly, ensuring that the water sample entering the TOC detection unit 12 and the enrichment module 2 is a "clear liquid phase." Using a smaller pore size (e.g., 0.45 μm) can intercept more particles, but it will significantly reduce the water sample permeation rate (flow rate may decrease by 50% under the same pressure), and may also trap some colloidal organic matter (0.1~1 μm in diameter) bound to zinc ions, resulting in a lower detected value for total organic carbon (TOC) (because colloidal organic matter is not included), thus misjudging the need for decontamination. On the other hand, pore sizes larger than 2 μm cannot effectively intercept key interfering particles of 1~2 μm. The choice of 1~2 μm strikes a balance between "interference interception" and "ensuring permeability".

[0081] Therefore, the combination of adjustable-speed pumping of 5~30 mL / min and filter membrane with pore size of 1~2μm forms a pretreatment mechanism of "dynamic adaptation and precise purification". The flow rate can be flexibly adjusted for water samples with different turbidity, which avoids clogging and reduces the loss of target substances. By intercepting key particles with precise pore size, physical interference and the risk of subsequent unit contamination are eliminated.

[0082] The two detection probes of the differential pressure sensor 113 are respectively set on the front and rear sides of the filter membrane 114 of the filter assembly 111; the differential pressure sensor 113 is connected to the main control module 4, and the differential pressure sensor 113 is used to detect the pressure difference of the test aqueous solution before and after passing through the filter assembly 111, and generate a differential pressure detection signal to be sent to the main control module 4; when the differential pressure value obtained by the differential pressure detection signal is greater than the preset differential pressure threshold, the main control module 4 prompts to replace the filter assembly.

[0083] Specifically, the differential pressure sensor generates a differential pressure detection signal and sends it to the main control module 4. The main control module 4 analyzes the obtained differential pressure detection signal. If the detected differential pressure value is greater than 0.3 MPa, the main control module 4 issues an alarm to prompt the replacement of the filter membrane 114, providing real-time and intelligent guidance on the operating status of the filter membrane 114.

[0084] During filtration, as suspended particulate matter accumulates on the membrane surface, the membrane pores gradually become clogged, leading to increased filtration resistance and a gradually rising pressure difference across the membrane. For membranes with 1-2 μm pore sizes, the pressure difference during normal filtration is typically stable at 0.05-0.15 MPa (fluctuating with water turbidity). When the amount of 1-2 μm particles adhering to the membrane surface reaches a certain level, the pressure difference will rapidly exceed 0.2 MPa. The 0.3 MPa setting provides a brief response buffer period (typically maintaining effective filtration for 3-5 minutes), ensuring timely alarm response while avoiding false alarms caused by instantaneous pressure fluctuations (such as the pulse at the moment of pump startup). If the filter membrane becomes excessively clogged (pressure difference > 0.3 MPa), the continuously rising pressure may cause micropores or tears in the membrane, allowing unfiltered particles to directly enter the total organic carbon detection unit or enrichment module, contaminating the optical path of the detection cell (affecting the detection accuracy at the 254 nm wavelength) or clogging the enrichment module (reducing zinc ion enrichment efficiency). The 0.3 MPa threshold provides pressure protection for downstream precision units by promptly terminating the filtration process, reducing equipment failure rates. Furthermore, when the pressure difference exceeds 0.3 MPa, the filtration effect of the membrane is severely degraded, potentially leading to "false negative filtration," where some particles penetrate the clogged membrane gaps with the water flow and enter subsequent units. Additionally, traditional membrane replacement relies on regular manual inspections (e.g., every 24 hours), but fluctuations in water turbidity can cause sudden membrane clogging within hours (e.g., in high-turbidity industrial wastewater), which is difficult to detect in real time through manual inspections, easily causing system shutdowns or distorted detection data. The 0.3MPa differential pressure alarm mechanism uses sensors for real-time monitoring and the main control module for automatic judgment. It can trigger an alarm immediately when the filter membrane is in a critical blockage state, so that operators can replace the filter membrane only when necessary, reducing the cost of ineffective inspections.

[0085] Therefore, the 0.3 MPa differential pressure threshold, by accurately matching the filter membrane characteristics and monitoring the clogging status in real time, not only realizes the intelligent management of filter membrane maintenance, but also reduces the detection error and equipment wear caused by filter failure from the source. It is a key parameter to ensure the stable operation of the entire monitoring system.

[0086] In one embodiment, the digester injection unit 14 includes a digester reagent storage device 141 and a second injection pump 142.

[0087] The digester reagent storage device 141 is connected to the digestion unit 13 via the second injection pump 142 and the second flow path control valve 52; the second injection pump 142 is connected to the main control module 4 and is used to receive the control signal of the main control module 4 to input the digester in the digester reagent storage device 141 to the digestion unit 13, wherein the digester is 0.1 mol / L dilute nitric acid.

[0088] Specifically, under the condition that the total organic carbon (TOC) value is greater than 10 mg / L, the main control module 4 controls the second flow path control valve 52 to open the flow path between the digester injection unit 14 and the digestion unit 13, and controls the second injection pump 142 to drive the digester in the digester injection unit 14 into the digestion unit 13 at a rate of 5 ~ 30 mL / min, where it is digested with the filtered test aqueous solution to eliminate the interference of organic matter during trace zinc ion detection. The digestion unit 13 then inputs the filtered and digested test aqueous solution into the enrichment module 2.

[0089] In one embodiment, the digestion unit 13 includes a heat exchange device 131, a digestion device 132, and a first peristaltic pump 133; the heat exchange device 131 includes a first heat exchange tube 131a and a second heat exchange tube 131b, the second heat exchange tube 131b being wound around the outer wall of the first heat exchange tube 131a.

[0090] One end of the first heat exchange tube 131a is connected to the total organic carbon detection unit 12 through the first flow path control valve 51, and the other end of the first heat exchange tube 131a is connected to the liquid inlet of the digestion device 132; one end of the second heat exchange tube 131b is connected to the liquid outlet of the digestion device 132, and the other end of the second heat exchange tube 131b is connected to the enrichment module 2 through the first peristaltic pump 133.

[0091] Specifically, the first heat exchange tube 131a is a glass spiral tube with an outer diameter of 4 to 8 mm, and the second heat exchange tube 131b is a polytetrafluoroethylene (PTFE) tube with an outer diameter of 1.2 to 2.0 mm and a length of 3 to 15 m. The heat exchange tube 131 is used to preheat the sample liquid and cool the high-temperature digested liquid flowing out of the digestion device 132. The digestion device 132 adopts an electrically heated aluminum column structure, with heating rods and temperature probes embedded at both ends of the column. The surface has spiral grooves to fix the PTFE coil and is covered with insulating quartz wool.

[0092] Specifically, the first heat exchange tube 131a is a glass spiral tube with an outer diameter of 4-8 mm. Due to the excellent thermal conductivity of glass, the spiral tube structure increases the contact area and contact time between the aqueous solution to be tested and the external environment (or the high-temperature digestion solution inside the second heat exchange tube). Combined with the 4-8 mm outer diameter, the first heat exchange tube 131a can efficiently absorb the heat transferred from the second heat exchange tube, ensuring sufficient preheating of the aqueous solution before it enters the digestion device, reducing the heating load on the digestion device, and shortening the time to reach the target reaction temperature. Furthermore, using a glass tube with an outer diameter of 4-8 mm can match the flow rate of the aqueous solution to be tested in the system (combined with an initial pump speed of 5-30 mL / min), ensuring smooth liquid flow while maintaining structural stability within a pressure range of 0.01-0.6 MPa, preventing rupture due to excessive pressure. Moreover, glass is chemically inert to most aqueous solutions (especially those containing acidic or weakly corrosive components), reducing the reaction between the tube and the solution and preventing the introduction of impurities that could interfere with subsequent detection.

[0093] Specifically, the second heat exchange tube 131b is a polytetrafluoroethylene (PTFE) tube with a length of 3 to 15 m and an outer diameter of 1.2 to 2.0 mm. PTFE has excellent high and low temperature resistance (-200 to 260 ℃) and thermal conductivity. The 1.2 to 2.0 mm outer diameter combined with the 3 to 15 m length significantly increases the heat exchange area between the high-temperature digestion liquid and the test liquid inside the first heat exchange tube. This allows the heat from the high-temperature liquid after digestion to be fully transferred to the test liquid to be preheated, achieving heat recovery and reducing system energy consumption. At the same time, it cools the high-temperature digestion liquid to a suitable temperature (preventing damage to the subsequent enrichment module due to excessive temperature). Moreover, PTFE has extremely strong corrosion resistance to strong acids, strong alkalis, and organic solvents, making it suitable for corrosive substances that may be generated during the digestion reaction. Furthermore, the material is flexible, making it easy to wrap around the outer wall of the first heat exchange tube, optimizing the heat exchange structure layout. Furthermore, the outer diameter is matched with the flow rate of the digested liquid, which ensures stable liquid flow within the pipe and guarantees adequate cooling performance through appropriate flow rate.

[0094] The digestion device 132 is equipped with a temperature and pressure detector (not shown) and a temperature and pressure controller (not shown). The temperature and pressure detector (not shown) is used to detect the temperature and pressure in the digestion device 132 and generate temperature and pressure detection signals to be sent to the main control module 4. The temperature and pressure controller (not shown) is used to receive the temperature and pressure control signals sent by the main control module 4 and to control the temperature and pressure of the digestion device 132 so that the pressure and temperature are controllable within the range of 0.01 ~ 0.6 MPa and 30 ~ 220 ℃, respectively.

[0095] Different types of organic compounds (such as humic acid and small-molecule organic compounds) require different digestion conditions. A temperature range of 30–220 °C covers the needs from low-temperature, gentle digestion to high-temperature, strong oxidative digestion (for example, simple organic compounds decompose at lower temperatures, while complex macromolecular organic compounds require temperatures above 200 °C). Pressure control of 0.01–0.6 MPa, combined with temperature regulation (such as increasing pressure at high temperatures to prevent liquid boiling), ensures efficient digestion in a liquid phase environment, improving the thoroughness of organic compound decomposition and reducing interference with subsequent trace zinc ion detection. Furthermore, real-time monitoring and adjustment of parameters via temperature and pressure detectors and controllers avoids risks such as device damage and liquid leakage due to excessive temperature or pressure. Stable pressure and temperature conditions also ensure the repeatability of the digestion reaction, guaranteeing consistent processing results across different batches of samples and improving the reliability of detection results. Furthermore, the pressure and temperature ranges of 0.01~0.6MPa and 30~220℃ respectively can be adapted to the optimal reaction conditions of different digesting agents (such as potassium persulfate, ozone, etc.), expanding the system's applicability to different water quality samples (such as surface water, industrial wastewater, etc.).

[0096] The filtered aqueous solution from the total organic carbon detection unit 12 flows into the digestion device 132 through the first flow path control valve 51 and the first heat exchange tube 131a. The digesting agent from the digesting agent injection unit 14 flows into the digestion device 132 through the second flow path control valve 52 and the first heat exchange tube 131a. The digestion reaction is carried out for 5 to 30 minutes at a pressure and temperature range of 0.01 ~ 0.6 MPa and 30 ~ 220 ℃, respectively. The filtered and digested aqueous solution flows into the enrichment module 2 through the second heat exchange tube 131b and the first peristaltic pump 133.

[0097] In one embodiment, the enrichment module 2 includes a balance adjustment unit 21, an enrichment unit 22, and a desorbent injection unit 23.

[0098] The balance adjustment unit 21 is connected to the enrichment unit 22 through the third flow path control valve 53; the balance adjustment unit 21 is used to balance the aqueous solution to be tested after filtration and digestion before inputting it to the enrichment unit 22.

[0099] The enrichment unit 22 is connected to the trace zinc ion detection module 3 through the fourth flow path control valve 54. The enrichment unit 22 is used to enrich and desorb zinc ions in the digested test aqueous solution, and input the desorbed test aqueous solution into the trace zinc ion detection module 3. The desorbent injection unit 23 is connected to the enrichment unit 22 through the third flow path control valve 53.

[0100] The main control module 4 is connected to the balance adjustment unit 21 and the enrichment unit 22. The main control module 4 is used to receive a first signal sent by the balance adjustment unit 21 and, based on the first signal, control the switching of the flow path of the third flow path control valve 53. The main control module 4 is also used to receive a second signal sent by the enrichment unit 22 and, based on the second signal, control the switching of the flow path of the third flow path control valve 53. The main control module 4 is also used to receive a third signal sent by the enrichment unit 22 and, based on the third signal, control the switching of the flow path of the fourth flow path control valve 54. The first signal is used to instruct the balance adjustment unit 21 to complete the balance adjustment operation; the second signal is used to instruct the enrichment unit 22 to complete the enrichment operation; and the third signal is used to instruct the enrichment unit 22 to complete the digestion operation.

[0101] In one embodiment, the desorbent injection unit 23 includes a desorbent reagent storage device 231, a fourth injection pump 232, and a first one-way valve 233.

[0102] One end of the fourth injection pump 232 is connected to the desorbent reagent storage device 231, and the other end of the fourth injection pump 232 is connected to the enrichment unit 22 through the first one-way valve 233 and the third flow path control valve 53 in sequence; the main control module 4 is used to control the fourth injection pump 232 to input the desorbent in the desorbent reagent storage device 231 to the enrichment unit 22.

[0103] Specifically, the balancing unit 21 includes a first valve-generating device 211, which stores an acetate-ammonium acetate buffer solution with a pH of 5.0–5.5. Since the pH of the filtered test solution may negatively affect the enrichment process of the enrichment unit 22 after digestion with a digesting agent, thus reducing the enrichment rate, the main control module 4 controls the balancing unit 21 to balance the filtered and digested test solution output from the digestion unit 13 at a volume ratio of 1:10 with the acetate-ammonium acetate buffer solution, ensuring that the pH of the filtered and digested test solution is between 3.0 and 5.0, meeting the pH requirements for enrichment.

[0104] After determining the balance adjustment, a first signal is sent to the main control module 4. Based on the first signal, the main control module 4 controls the switching of the third flow path control valve 53, opens the flow path between the balance adjustment unit 21 and the enrichment unit 22, and closes the flow path between the desorbent injection unit 23 and the enrichment unit 22, so that the test aqueous solution after the balance adjustment operation is completed is input into the enrichment unit 22 for enrichment operation.

[0105] The pH value of the filtered test aqueous solution output from the total organic carbon detection unit 12 does not need to be adjusted. The main control module 4 controls the third flow path control valve 53 to open the flow path between the balance adjustment unit 21 and the enrichment unit 22, and close the flow path between the desorbent injection unit 23 and the enrichment unit 22, so that the filtered test aqueous solution is input into the enrichment unit 22 through the balance adjustment unit 21 for enrichment operation.

[0106] After the enrichment unit 22 completes the enrichment operation, it sends a second signal to the main control module 4. Based on the second signal, the main control module 4 controls the third flow path control valve 53 to open the flow path between the desorbent injection unit 23 and the enrichment unit 22. Simultaneously, the main control module 4 generates a corresponding control signal and sends it to the fourth syringe pump 232, controlling the fourth syringe pump 232 to input the desorbent from the desorbent reagent storage device 231 into the enrichment unit 22 for digestion at a rate of 1~2 mL / min. After the enrichment unit 22 completes the digestion operation, it sends a third signal to the main control module 4. Based on the third signal, the main control module 4 controls the fourth flow path control valve 54 to open the flow path between the enrichment unit 22 and the trace zinc ion detection module 3, inputting the digested test aqueous solution into the trace zinc ion detection module 3 for zinc ion detection. The desorbent used is 0.5~2% dilute nitric acid.

[0107] Among them, the desorbent delivery rate of 1~2 mL / min plays a key role in balancing efficiency and accuracy and improving automation reliability in the whole detection system by ensuring desorption efficiency, maintaining flow path stability, adapting to trace detection requirements and protecting equipment.

[0108] Specifically, a flow rate of 1-2 mL / min falls within the low-speed, stable delivery range, allowing the desorbent to fully contact the adsorbent material (such as resin or filler adsorbed with the target analyte) in enrichment unit 22, thus extending the contact time. This low-speed flow avoids localized incomplete reactions caused by rapid desorbent scouring, ensuring complete desorption of enriched substances (such as zinc ions and related organic matter), reducing residues, and providing a more accurate sample substrate for subsequent trace zinc ion detection. Trace zinc ion detection places extremely high demands on sample concentration and stability. A flow rate of 1-2 mL / min controls the amount of desorbent used, preventing excessive dilution of the solution after desorption and ensuring the target analyte concentration remains within the sensitivity range of the detection module. If the flow rate is too high, it may result in excessive desorbent usage, diluting the target analyte; if the flow rate is too slow, it will prolong the overall analysis time and reduce detection efficiency. A flow rate of 1-2 mL / min strikes a balance between efficiency and concentration maintenance, balancing detection speed and accuracy.

[0109] Furthermore, a flow rate of 1–2 mL / min is matched with the overall flow path design of the digestion and enrichment units (such as the diameter and material of the previously mentioned glass spiral tubes and PTFE tubes), which reduces pressure fluctuations within the flow path. At this rate, the desorbent flows smoothly in the tubing, preventing sample loss or leakage at tubing connections due to turbulence or sudden pressure changes, ensuring that the desorbed solution can enter the subsequent flow path intact and stably. Moreover, the low flow rate of 1–2 mL / min facilitates precise control of the entire process by the main control module 4, enabling coordination with other units (such as temperature and pressure control in the digestion unit and signal acquisition rhythm in the detection module) to ensure parameter matching at each stage and improve the overall automation and stability of the system. The enrichment unit and subsequent flow paths typically use corrosion-resistant materials such as PTFE, but high-speed delivery may exacerbate tubing wear or joint aging. The low flow rate of 1–2 mL / min reduces fluid erosion of the tubing inner walls, extends tubing life, and reduces maintenance costs.

[0110] In one embodiment, the enrichment unit 22 includes a pressure sensor 221, a first enrichment column 222, a second one-way valve 223, a second enrichment column 224, and a third one-way valve 225.

[0111] One end of the pressure sensor 221 is connected to the balance adjustment unit 21 through the third flow path control valve 53; the other end of the pressure sensor 221 is connected to one end of the first enrichment column 222, and the other end of the pressure sensor 221 is connected to one end of the second enrichment column 224 through the fifth flow path control valve 55; the other end of the first enrichment column 222 is connected to the trace zinc ion detection module 3 through the second one-way valve 223 and the fourth flow path control valve 54 in sequence; the other end of the second enrichment column 224 is connected to the trace zinc ion detection module 3 through the third one-way valve 225 and the fifth flow path control valve 55 in sequence.

[0112] Pressure sensor 221 detects the flow path pressure in enrichment unit 22 and sends the generated pressure detection signal to main control module 4. Main control module 4 analyzes the received pressure detection signal. When the flow path pressure is less than or equal to a preset flow path pressure threshold, main control module 4 controls the fifth flow path control valve 55 to close, and inputs the digested aqueous solution to be tested into the first enrichment column 222 for enrichment and desorption. When the flow path pressure is greater than the flow path pressure threshold, main control module 4 controls the fifth flow path control valve 55 to open, and inputs the digested aqueous solution to be tested into the first enrichment column 222 and the second enrichment column 224 respectively for enrichment and desorption.

[0113] Specifically, in order to improve the enrichment efficiency and avoid excessive solution flow leading to excessive system resistance and affecting the precision of the system, pressure sensor 221 detects the flow path pressure in enrichment unit 22 in real time and sends the generated pressure detection signal to main control module 4. Main control module 4 analyzes the received pressure detection signal. When the flow path pressure is less than or equal to a preset flow path pressure threshold, for example, when the flow path pressure is less than or equal to 2.80 MPa, main control module 4 controls the fifth flow path control valve 55 to close, closing the flow path between balance adjustment unit 21 and second enrichment column 224, as well as the flow path between desorbent injection unit 23 and second enrichment column 224, so that enrichment and desorption are concentrated in first enrichment column 222. When the flow path pressure exceeds the preset flow path pressure threshold, for example, when the flow path pressure exceeds 2.80 MPa, the main control module 4 controls the fifth flow path control valve 55 to open, opening the flow path between the balance adjustment unit 21 and the second enrichment column 224, as well as the flow path between the desorbent injection unit 23 and the second enrichment column 224, forming a diversion effect. This allows the solution input into the enrichment unit 22 to flow into the second enrichment column 224 through the fifth flow path control valve 55 for enrichment and desorption. By using a dual pressure and volume control method for injection, the system resistance is effectively reduced. Furthermore, the single and dual column flow paths can be dynamically switched automatically through pressure feedback to meet the flow rate requirements of different enrichment multiples of trace zinc ions in the solution. At the same time, the second one-way valve 223 and the third one-way valve 225 are used to ensure unidirectional flow of the solution and avoid backflow causing contamination.

[0114] The system includes components such as pipes (e.g., PTFE pipes), valves (fifth flow path control valve 55), and enrichment columns (first enrichment column 222, second enrichment column 224), all of which have their own pressure resistance limits. The 2.8 MPa threshold is determined based on the material properties (e.g., the pressure resistance of PTFE) and structural strength of these components. This ensures that excessive pressure can prevent pipe rupture, interface leakage, and other hardware damage, while also guaranteeing the stability of the flow path during normal enrichment and desorption processes.

[0115] Furthermore, during the enrichment process, the flow rate and pressure of the solution within the enrichment column directly affect the adsorption efficiency of the target analyte (trace zinc ions) and the enrichment material: Too low a pressure may result in a slow flow rate, prolonging the enrichment time; too high a pressure will reduce the sufficient contact between the solution and the enrichment material due to excessive flow resistance, and may even cause some solution to flow out without being effectively adsorbed. The 2.8 MPa threshold has been optimized to ensure enrichment efficiency during single-column operation (pressure ≤ 2.8 MPa), while reserving a reasonable pressure buffer for dual-column split flow. The viscosity, suspended solids content, and other characteristics of the test solution may vary. When the solution viscosity is high or the flow rate is large, the flow resistance will increase significantly. The 2.8 MPa threshold can serve as a critical point for determining whether a single column can handle the current flow rate, ensuring that the system can automatically switch flow paths through pressure feedback when solution characteristics fluctuate, avoiding a decrease in enrichment effect due to insufficient flow rate adaptability.

[0116] In one embodiment, the trace zinc ion detection module 3 includes a pH adjustment unit 31 and a trace zinc ion detection unit 32.

[0117] pH adjustment unit 31 is connected to enrichment module 2 through fourth flow path control valve 54; pH adjustment unit 31 is connected to trace zinc ion detection unit 32; pH adjustment unit 31 is used to adjust the pH of the desorbed aqueous solution to be tested and input it to trace zinc ion detection unit 32 for zinc ion detection.

[0118] The pH adjustment unit 31 includes a second valve-generating device 311 and a fifth injection pump 312; one end of the fifth injection pump 312 is connected to the second valve-generating device 311, and the other end of the fifth injection pump 312 is connected to the trace zinc ion detection unit 32; the main control module 4 controls the second valve-generating device 311 to release buffer solution to adjust the pH value of the desorbed test aqueous solution input to the second valve-generating device 311; the main control module 4 is used to control the fifth injection pump 312 to input the pH-adjusted test aqueous solution to the trace zinc ion detection unit 32.

[0119] Specifically, the trace zinc ion detection unit 32 can perform trace zinc ion detection using spectroscopic methods (zinc reagent colorimetric method), mass spectrometry (ICP-MS), or electrochemical methods (potentiometric titration). Different zinc ion detection methods have different pH requirements. The main control module 4 controls the generator 311 on the second valve to release the corresponding buffer solution according to the trace zinc ion detection method used by the trace zinc ion detection unit 32, thereby adjusting the pH value of the desorbed test aqueous solution input from the enrichment unit 22 to the generator 311 on the second valve. Specifically, if mass spectrometry is used, pH adjustment of the desorbed test solution is not required; if zinc reagent colorimetric method is used, the buffer solution is a borate buffer with a pH of 10.5-11.5, and the volume ratio of the buffer solution to the desorbed test solution is in the range of [3, 4]. The pH of the desorbed test solution is then adjusted to 8.8-9.0; if potentiometric titration method is used, the buffer solution is an ammonium acetate buffer with a pH of 6.5-7.5, and the volume ratio of the buffer solution to the desorbed test solution is in the range of [3, 4]. The pH of the desorbed test solution is then adjusted to 6.5-7.5 to meet the pH requirements of zinc ion detection methods in specific application scenarios and improve the accuracy of zinc ion detection.

[0120] After the pH adjustment unit 31 completes the pH adjustment operation, the main control module 4 controls the fifth injection pump 312 to input the pH-adjusted aqueous solution to the trace zinc ion detection unit 32 for zinc ion detection. The trace zinc ion detection unit 32 generates a trace zinc ion detection signal and sends it to the main control module 4. The main control module 4 analyzes the obtained trace zinc ion detection signal to obtain the trace zinc ion detection result.

[0121] Please refer to Figure 2 , Figure 2 A schematic diagram of the structure of an online monitoring system for trace zinc ions in an aqueous solution provided in another embodiment of this application.

[0122] In one embodiment, the system further includes a waste liquid collection unit 6; the waste liquid collection unit 6 includes a waste liquid collection device 61, a fourth check valve 62, and a second peristaltic pump 63.

[0123] One inlet of the waste liquid collection device 61 is connected to the enrichment unit 22 through the fourth flow path control valve 54; the other inlet of the waste liquid collection device 61 is connected to the trace zinc ion detection unit 32 through the fourth one-way valve 62 and the second peristaltic pump 63 in sequence; the main control module 4 is used to switch the flow path of the fourth flow path control valve 54 to input the aqueous solution to be tested in the enrichment unit 22 into the waste liquid collection device 61.

[0124] Specifically, to further improve the enrichment effect of the enrichment unit, a waste liquid collection device 61 is provided. The enrichment unit 22 can input the aqueous solution from the first enrichment column 222 and the second enrichment column 224 into the waste liquid collection device 61 through the fourth flow path control valve 52. This allows the test aqueous solution with a decreased zinc ion content after the enrichment operation to leave the first enrichment column 222 and the second enrichment column 224, enabling the test aqueous solution with a higher zinc ion content to be input from the balance adjustment unit 21 into the first enrichment column 222 and the second enrichment column 224, thereby improving the enrichment efficiency. Furthermore, after the trace zinc ion detection unit 32 completes the trace zinc ion detection, the liquid after the trace zinc ion detection is sequentially input into the waste liquid collection device 61 through the second peristaltic pump 62 and the fourth one-way valve 63 to maintain the accuracy of the trace zinc ion detection.

[0125] In one embodiment, the system further includes a cleaning agent injection unit 7; the cleaning agent injection unit 7 includes a cleaning agent storage device 71, a sixth injection pump 72, a fifth check valve 73, a seventh injection pump 74, and a sixth check valve 75.

[0126] One end of the sixth injection pump 72 is connected to the cleaning agent storage device 71, and the other end of the sixth injection pump 72 is connected to the enrichment unit 22 through the fifth one-way valve 73 and the third flow path control valve 53 in sequence; one end of the seventh injection pump 74 is connected to the cleaning agent storage device 71, and the other end of the seventh injection pump 74 is connected to the pH adjustment unit 31 through the sixth one-way valve 75 and the three-way valve 33 in sequence.

[0127] The main control module 4 is used to respond to the system cleaning signal, control the sixth injection pump 72 to input the cleaning agent in the cleaning agent storage device 71 into the enrichment unit 22 through the fifth one-way valve 73 and the third flow path control valve 53, and control the seventh injection pump 74 to input the cleaning agent in the cleaning agent storage device 71 into the pH adjustment unit 31 through the sixth one-way valve 75.

[0128] Specifically, after the trace zinc ion detection is completed, the main control module 4 sends corresponding control signals to the sixth injection pump 72 and the seventh injection pump 74, controlling the sixth injection pump 72 and the seventh injection pump 74 to start working. The sixth injection pump 72 drives the cleaning solution stored in the cleaning agent storage device 71 to flow at a rate of 10 mL / min through the fifth one-way valve 73 and the first flow path control valve 51 to the enrichment unit 22 to clean the enrichment unit 22, ensuring that the first enrichment column 222 and the second enrichment column 224 in the enrichment unit 22 are rinsed to neutral (for 1 min), ensuring the regeneration and reusability of the anion exchange resin or chelating resin used as the first enrichment column 222 and the second enrichment column 224. The seventh injection pump 74 drives the cleaning solution stored in the cleaning agent storage device 71 to flow through the sixth one-way valve 75 to the pH adjustment unit 31 to clean the pH adjustment unit 31.

[0129] In an optional embodiment, the flow paths, flow path control valves, injection pumps, and peristaltic pumps of the above system can be made of materials such as polytetrafluoroethylene or polyetheretherketone, which are resistant to acid and alkali corrosion and free from metal contamination.

[0130] In a liquid delivery system, a syringe pump draws and delivers solutions, and can precisely control the solution volume and flow rate; a flow path control valve is used to open, close, and switch the flow path; a check valve is used to ensure unidirectional flow of the solution and prevent backflow from causing contamination.

[0131] In an optional embodiment, this application also discloses an online monitoring method for trace zinc ions applied to an online monitoring system for trace zinc ions in aqueous solutions. Please refer to [link to relevant documentation]. Figure 3 , Figure 3 The flowchart of an online monitoring method for trace zinc ions in an aqueous solution provided in an embodiment of this application includes steps S1 to S3, as detailed below:

[0132] S1: The sampling and processing module 1 filters the input aqueous solution to be tested, and performs total organic carbon detection and signal generation on the filtered aqueous solution at a preset wavelength to obtain the total organic carbon detection signal and send it to the main control module 4.

[0133] Total organic carbon is prone to generating carbon-based polyatomic ion interference, and high organic matter content leads to matrix effects and cone pore blockage.

[0134] In this embodiment, the sample sampling unit 11 in the sampling processing module 1 is used to sample the aqueous solution to be tested. The sample sampling unit 11 inputs the filtered aqueous solution to the total organic carbon detection unit 12. The total organic carbon detection unit 12 performs total organic carbon detection and signal generation on the filtered aqueous solution at a preset wavelength, specifically 254 nm, for 5 minutes to obtain a total organic carbon detection signal. The total organic carbon detection unit 12 sends the total organic carbon detection signal to the main control module 4. The main control module 4 analyzes the obtained total organic carbon detection signal to obtain the total organic carbon value.

[0135] S2: The main control module 4 analyzes the obtained total organic carbon detection signal to obtain the total organic carbon value; when the total organic carbon value is less than or equal to the preset total organic carbon threshold, the main control module 4 controls the sampling processing module 1 to transport the filtered test aqueous solution to the enrichment module 2; when the total organic carbon value is greater than the total organic carbon threshold, the main control module 4 controls the sampling processing module 1 to digest the filtered test aqueous solution and transport the digested test aqueous solution to the enrichment module 2.

[0136] In this embodiment of the application, if the total organic carbon value (TOC) is ≤ 10 mg / L, it means that the filtered aqueous solution meets the enrichment requirements. The main control module 4 controls the first flow path control valve 51 to open the flow path between the total organic carbon detection unit 12 and the balance adjustment unit 21. The total organic carbon detection unit 12 inputs the filtered aqueous solution to the balance adjustment unit 21.

[0137] If the total organic carbon (TOC) value is greater than 10 mg / L, it indicates that the filtered aqueous solution does not meet the enrichment requirements. The main control module 4 controls the first flow path control valve 51 to close the flow path between the total organic carbon detection unit 12 and the balance adjustment unit 21, and to open the flow path between the total organic carbon detection unit 12 and the digestion unit 13, so that the total organic carbon detection unit 12 can input the filtered aqueous solution to the digestion unit 13 for digestion treatment to meet the enrichment requirements.

[0138] The main control module 4 controls the second flow path control valve 52 to open the flow path between the digester injection unit 14 and the digestion unit 13; so that the digester injection unit 14 can promptly input the digester into the digestion unit 13, and react with the filtered test aqueous solution in a timely manner, thereby improving the operating efficiency of the device.

[0139] After the flow path is opened, the total organic carbon detection unit 12 inputs the filtered test aqueous solution into the digestion unit 13 for digestion. The digestion unit 13 inputs the filtered and digested test aqueous solution into the balance adjustment unit 21. Since the pH value of the filtered test aqueous solution after digestion may have a negative impact on the enrichment process of the enrichment unit 22, the main control module 4 controls the balance adjustment unit 21 to adjust the pH value of the filtered and digested test aqueous solution so that the pH value of the filtered and digested test aqueous solution meets the pH value requirements for enrichment. The pH value-adjusted test aqueous solution is then input into the enrichment unit 22 for enrichment and desorption, thereby improving the enrichment and desorption efficiency.

[0140] S3: The enrichment module 2 enriches trace zinc ions in the input aqueous solution to be tested. The main control module 4 controls the enrichment module 2. When the aqueous solution to be tested meets the detection conditions, the enriched and desorbed aqueous solution to be tested is transported to the trace zinc ion detection module 3. The main control module 4 controls the trace zinc ion detection module 3 to perform trace zinc ion detection.

[0141] In this embodiment, since different zinc ion detection methods have different pH requirements, in order to meet the pH requirements of the zinc ion detection method and improve the accuracy of zinc ion detection, the main control module 4 controls the pH adjustment unit 31 to adjust the pH of the desorbed test aqueous solution according to the trace zinc ion detection method adopted by the trace zinc ion detection unit 32, and inputs it to the trace zinc ion detection unit 32 for zinc ion detection; the trace zinc ion detection unit 32 generates a trace zinc ion detection signal and sends it to the main control module 4, and the main control module 4 analyzes the obtained trace zinc ion detection signal to obtain the trace zinc ion detection result.

[0142] Specifically, when the zinc ion detection method uses mass spectrometry, the main control module 4 determines that it is not necessary to adjust the pH value of the desorbed aqueous solution.

[0143] When the zinc ion detection method adopts the zinc reagent colorimetric method, the main control module 4 controls the pH adjustment unit 31 to release the second buffer solution to adjust the pH value of the desorbed test aqueous solution to 8.8-9.0. The second buffer solution is a borate buffer solution with a pH value of 10.5-11.5, and the volume ratio of the second buffer solution to the desorbed test aqueous solution is in the range of [3, 4].

[0144] When the zinc ion detection method adopts potentiometric titration, the main control module 4 controls the pH adjustment unit to release the third buffer solution to adjust the pH value of the desorbed test aqueous solution to 5.5. The third buffer solution is an ammonium acetate buffer solution with a pH value of 6.5-7.5, and the volume ratio of the third buffer solution to the desorbed test aqueous solution is in the range of [3, 4].

[0145] In this embodiment, the solution is automatically injected via intelligent control, pretreated, and then automatically enriched via an enrichment column. After enrichment, it enters the detection device for automatic online detection. This solves the problems of low sensitivity, complex operation, and low detection efficiency of traditional detection methods, and realizes automated monitoring. It has the technical effects of high sensitivity, high degree of automation, strong anti-interference ability, and low operating cost.

[0146] This application provides an online monitoring system and method for trace zinc ions in aqueous solutions, which solves the problems of low sensitivity, complex operation, and low detection efficiency of traditional detection methods. It is suitable for intelligent and automated monitoring of surface water, drinking water, and aqueous solutions in specific application scenarios, and features high sensitivity, high degree of automation, strong anti-interference ability, and low operating cost.

[0147] This invention is not limited to the above-described embodiments. If any modifications or variations to this invention do not depart from the spirit and scope of this invention, and if such modifications and variations fall within the scope of the claims and equivalent technologies of this invention, then this invention also intends to include such modifications and variations.

Claims

1. An online monitoring system for trace zinc ions in aqueous solution, characterized in that, include: The sampling and processing module (1), the enrichment module (2), the trace zinc ion detection module (3), and the main control module (4) are included. The sampling processing module (1) is connected to the enrichment module (2); the sampling processing module (1) is used to filter the aqueous solution to be tested and to detect the total organic carbon in the filtered aqueous solution to be tested. When the total organic carbon value is less than or equal to the preset total organic carbon threshold, the filtered aqueous solution to be tested is input to the enrichment module (2). When the total organic carbon value is greater than the total organic carbon threshold, the aqueous solution to be tested is digested and then input to the enrichment module (2). The enrichment module (2) is connected to the trace zinc ion detection module (3). The enrichment module (2) is used to enrich the input test aqueous solution with trace zinc ions and to transport the enriched test aqueous solution to the trace zinc ion detection module (3). The enrichment module (2) includes a balance adjustment unit (21), an enrichment unit (22), and a desorbent injection unit (23). The balance adjustment unit (21) is connected to the enrichment unit (22) through the third flow path control valve (53); the balance adjustment unit (21) is used to balance the aqueous solution to be tested after filtration and digestion and then input it to the enrichment unit (22). The enrichment unit (22) is connected to the trace zinc ion detection module (3) through the fourth flow path control valve (54); the enrichment unit (22) is used to enrich and desorb zinc ions in the digested test aqueous solution, and input the desorbed test aqueous solution into the trace zinc ion detection module (3); the desorbent injection unit (23) is connected to the enrichment unit (22) through the third flow path control valve (53); The main control module (4) is connected to the balance adjustment unit (21) and the enrichment unit (22); the main control module (4) is used to receive a first signal sent by the balance adjustment unit (21), and according to the first signal, control the switching of the flow path of the third flow path control valve (53); the main control module (4) is also used to receive a second signal sent by the enrichment unit (22), and according to the second signal, control the switching of the flow path of the third flow path control valve (53); the main control module (4) is also used to receive a third signal sent by the enrichment unit (22), and according to the third signal, control the switching of the flow path of the fourth flow path control valve (54), wherein the first signal is used to instruct the balance adjustment unit (21) to complete the balance adjustment operation; the second signal is used to instruct the enrichment unit (22) to complete the enrichment operation; the third signal is used to instruct the enrichment unit (22) to complete the digestion operation; The enrichment unit (22) includes a pressure sensor (221), a first enrichment column (222), a second check valve (223), a second enrichment column (224), and a third check valve (225). One end of the pressure sensor (221) is connected to the balance adjustment unit (21) through the third flow path control valve (53); the other end of the pressure sensor (221) is connected to one end of the first enrichment column (222), and the other end of the pressure sensor (221) is connected to one end of the second enrichment column (224) through the fifth flow path control valve (55); the other end of the first enrichment column (222) is connected to the trace zinc ion detection module (3) through the second one-way valve (223) and the fourth flow path control valve (54) in sequence; the other end of the second enrichment column (224) is connected to the trace zinc ion detection module (3) through the third one-way valve (225) and the fifth flow path control valve (55) in sequence. The pressure sensor (221) detects the flow path pressure in the enrichment unit (22) and sends the generated pressure detection signal to the main control module (4). The main control module (4) analyzes the received pressure detection signal. When the flow path pressure is less than or equal to the preset flow path pressure threshold, the main control module (4) controls the fifth flow path control valve (55) to close and inputs the digested aqueous solution to the first enrichment column (222) for enrichment and desorption. When the flow path pressure is greater than the flow path pressure threshold, the main control module (4) controls the fifth flow path control valve (55) to open and inputs the digested aqueous solution to the first enrichment column (222) and the second enrichment column (224) for enrichment and desorption, respectively. The trace zinc ion detection module (3) is used to detect trace zinc ions in the enriched aqueous solution to be tested. The main control module (4) is connected to the sampling and processing module (1), the enrichment module (2), and the trace zinc ion detection module (3). The main control module (4) is used to receive the total organic carbon detection result detected by the sampling and processing module (1), and control the sampling and processing module (1) to digest the aqueous solution to be tested or to transport the aqueous solution to be tested to the enrichment module (2) based on the total organic carbon detection result. The main control module (4) is used to control the enrichment module (2) to transport the aqueous solution to be tested after enrichment and desorption to the trace zinc ion detection module (3) when the aqueous solution to be tested meets the detection conditions. The main control module (4) is used to control the trace zinc ion detection module (3) to perform detection.

2. The online monitoring system for trace zinc ions in aqueous solution according to claim 1, characterized in that: The sampling and processing module (1) includes a sample sampling unit (11), a total organic carbon detection unit (12), a digestion unit (13), and a digesting agent injection unit (14). The sample sampling unit (11) is connected to the total organic carbon detection unit (12). The sample sampling unit (11) is used to filter the aqueous solution to be tested and then transmit it to the total organic carbon detection unit (12). The total organic carbon detection unit (12) is connected to the digestion unit (13) and the enrichment module (2) respectively through the first flow path control valve (51). The digestion unit (13) is connected to the enrichment module (2). The total organic carbon detection unit (12) is used to detect the total organic carbon in the filtered aqueous solution to be tested. When the total organic carbon value is less than or equal to the preset total organic carbon threshold, the filtered aqueous solution to be tested is input to the enrichment module (2). When the total organic carbon value is greater than the total organic carbon threshold, the aqueous solution to be tested is digested by the digestion unit (13) and then input to the enrichment module (2). The digesting agent injection unit (14) is connected to the digestion unit (13) through the second flow path control valve (52). The main control module (4) is connected to the total organic carbon detection unit (12). The main control module (4) is used to receive the total organic carbon detection signal sent by the total organic carbon detection unit (12) and control the switching of the first flow path control valve (51) and the opening and closing of the second flow path control valve (52) according to the total organic carbon detection signal.

3. The online monitoring system for trace zinc ions in aqueous solution according to claim 2, characterized in that: The sample sampling unit (11) includes a filter assembly (111), a first injection pump (112), and a differential pressure sensor (113). The filter assembly (111) is connected to the total organic carbon detection unit (12) via the first injection pump (112); the first injection pump (112) is connected to the main control module (4) and is used to receive the control signal of the main control module (4) and transmit the filtered aqueous solution to be tested to the total organic carbon detection unit (12). The two detection probes of the differential pressure sensor (113) are respectively set on the front and rear sides of the filter membrane (114) of the filter assembly (111); the differential pressure sensor (113) is connected to the main control module (4), and the differential pressure sensor (113) is used to detect the pressure difference of the aqueous solution to be tested before and after passing through the filter assembly (111), and generate a differential pressure detection signal to be sent to the main control module (4); when the differential pressure value obtained based on the differential pressure detection signal is greater than the preset differential pressure threshold, the main control module (4) prompts to replace the filter assembly.

4. The online monitoring system for trace zinc ions in aqueous solution according to claim 2, characterized in that: The digestion unit (13) includes a heat exchange device (131), a digestion device (132), and a first peristaltic pump (133); the heat exchange device (131) includes a first heat exchange tube (131a) and a second heat exchange tube (131b), the second heat exchange tube (131b) being wound around the outer wall of the first heat exchange tube (131a); One end of the first heat exchange tube (131a) is connected to the total organic carbon detection unit (12) through the first flow path control valve (51), and the other end of the first heat exchange tube (131a) is connected to the liquid inlet of the digestion device (132); one end of the second heat exchange tube (131b) is connected to the liquid outlet of the digestion device (132), and the other end of the second heat exchange tube (131b) is connected to the enrichment module (2) through the first peristaltic pump (133).

5. The online monitoring system for trace zinc ions in aqueous solution according to claim 1, characterized in that: The trace zinc ion detection module (3) includes a pH adjustment unit (31) and a trace zinc ion detection unit (32). The pH adjustment unit (31) is connected to the enrichment module (2) through the fourth flow path control valve (54); the pH adjustment unit (31) is connected to the trace zinc ion detection unit (32); the pH adjustment unit (31) is used to adjust the pH of the desorbed aqueous solution to be tested and input it to the trace zinc ion detection unit (32) for zinc ion detection. The pH adjustment unit (31) includes a second valve-generating device (311) and a fifth injection pump (312); one end of the fifth injection pump (312) is connected to the second valve-generating device (311), and the other end of the fifth injection pump (312) is connected to the trace zinc ion detection unit (32); the main control module (4) controls the second valve-generating device (311) to release buffer solution to adjust the pH value of the desorbed test aqueous solution input to the second valve-generating device (311); the main control module (4) is used to control the fifth injection pump (312) to input the pH-adjusted test aqueous solution to the trace zinc ion detection unit (32).

6. The online monitoring system for trace zinc ions in aqueous solution according to claim 5, characterized in that: The system also includes a waste liquid collection unit (6); the waste liquid collection unit (6) includes a waste liquid collection device (61), a fourth check valve (62) and a second peristaltic pump (63). One inlet of the waste liquid collection device (61) is connected to the enrichment unit (22) through the fourth flow path control valve (54); the other inlet of the waste liquid collection device (61) is connected to the trace zinc ion detection unit (32) through the fourth one-way valve (62) and the second peristaltic pump (63) in sequence; the main control module (4) is used to control the switching of the fourth flow path control valve (54).

7. The online monitoring system for trace zinc ions in aqueous solution according to claim 5, characterized in that: The system also includes a cleaning agent injection unit (7); the cleaning agent injection unit (7) includes a cleaning agent storage device (71), a sixth injection pump (72), a fifth check valve (73), a seventh injection pump (74), and a sixth check valve (75); One end of the sixth injection pump (72) is connected to the cleaning agent storage device (71), and the other end of the sixth injection pump (72) is connected to the enrichment unit (22) in sequence through the fifth one-way valve (73) and the third flow path control valve (53); one end of the seventh injection pump (74) is connected to the cleaning agent storage device (71), and the other end of the seventh injection pump (74) is connected to the pH adjustment unit (31) in sequence through the sixth one-way valve (75) and the three-way valve (33); The main control module (4) is used to respond to the system cleaning signal, control the sixth injection pump (72) to input the cleaning agent in the cleaning agent storage device (71) to the enrichment unit (22) through the fifth one-way valve (73) and the third flow path control valve (53), and control the seventh injection pump (74) to input the cleaning agent in the cleaning agent storage device (71) to the pH adjustment unit (31) through the sixth one-way valve (75).

8. A method for online monitoring of trace zinc ions in aqueous solution using an online monitoring system for trace zinc ions as described in any one of claims 1 to 7, comprising the steps of: The sampling processing module (1) filters the input aqueous solution to be tested, and performs total organic carbon detection and signal generation on the filtered aqueous solution at a preset wavelength to obtain a total organic carbon detection signal and send it to the main control module (4). The main control module (4) analyzes the obtained total organic carbon detection signal to obtain the total organic carbon value; when the total organic carbon value is less than or equal to the preset total organic carbon threshold, the main control module (4) controls the sampling processing module (1) to transport the filtered test aqueous solution to the enrichment module (2); when the total organic carbon value is greater than the total organic carbon threshold, the main control module (4) controls the sampling processing module (1) to digest the filtered test aqueous solution and transport the digested test aqueous solution to the enrichment module (2). The enrichment module (2) enriches the input test aqueous solution with trace zinc ions. When the test aqueous solution meets the detection conditions, the main control module (4) controls the enrichment module (2) to transport the enriched and desorbed test aqueous solution to the trace zinc ion detection module (3). The main control module (4) controls the trace zinc ion detection module (3) to perform trace zinc ion detection.

Images