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

Abstract

The invention relates to the technical field of analysis and detection, in particular to an online monitoring method and system for trace zinc ions in an aqueous solution. A sampling processing module filters an input aqueous solution to be detected and carries out total organic carbon detection on the filtered aqueous solution under a preset wavelength; digesting the filtered aqueous solution to be detected according to a total organic carbon detection result, and conveying the digested aqueous solution to an enrichment module, or conveying the filtered aqueous solution to be detected to the enrichment module; the enrichment module is used for carrying out trace zinc ion enrichment on the input aqueous solution to be detected, and the desorbed aqueous solution to be detected after enrichment is conveyed to the trace zinc ion detection module for trace zinc ion detection. The problems that a traditional detection method is low in sensitivity, complex in operation, low in detection efficiency and the like are solved, and the method is suitable for intelligent and automatic monitoring of surface water, drinking water, specific application scene water solutions and the like and has the advantages of being high in sensitivity, automation degree and anti-interference capacity and low in operation cost.

Description

Technical Field

[0001] The present invention relates to the technical field of analysis and detection, and in particular to an online monitoring method and system for trace zinc ions in an aqueous solution. Background Art

[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 relatively low in aqueous solutions such as surface water, groundwater, drinking water, and aqueous solutions in specific industrial processes, the sensitivity of zinc detection methods in aqueous solutions is increasingly demanding.

[0003] Currently, methods for detecting zinc in aqueous solutions primarily include chemical analysis, spectroscopy, mass spectrometry, electrochemistry, and biochemistry. Chemical analysis primarily involves titration, which requires manual intervention and is difficult to automate. Spectroscopic methods primarily include colorimetry and atomic absorption spectrometry. Colorimetry is low-cost but has low sensitivity and requires strict pH control; atomic absorption spectrometry is highly sensitive but also expensive and lacks real-time performance. Mass spectrometry offers high sensitivity and stability, but is limited by cost, operational complexity, installation requirements, and maintenance requirements. Electrochemical methods commonly include anodic stripping voltammetry (ASV) and potentiometric titration. ASV offers high sensitivity but poor anti-interference capabilities and electrode stability. Potentiometric titration is highly automated but has low sensitivity and slow dynamic response. Biochemical methods primarily include enzyme inhibition and immunoassays, which have yet to be applied in online testing.

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

[0005] Based on this, the purpose of the present invention is to provide an online monitoring system and method for trace zinc ions in aqueous solution, 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 has the characteristics of high sensitivity, high degree of automation, strong anti-interference ability, and low operating cost. The technical solution is as follows: In a first aspect, the present application discloses an online monitoring system for trace zinc ions in an 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; The sampling and processing module 1 is connected to the enrichment module 2; the sampling and processing module 1 is used to filter the aqueous solution to be tested and perform total organic carbon detection on the filtered aqueous solution to be tested. When the total organic carbon value is less than or equal to a preset total organic carbon threshold, the filtered aqueous solution to be tested is input into 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 into 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 aqueous solution to be tested for trace zinc ions and transport the enriched aqueous solution to be tested to the trace zinc ion detection module 3; 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 based on the total organic carbon detection result, control the sampling and processing module 1 to digest the aqueous solution to be tested or transport the aqueous solution to be tested to the enrichment module 2; the main control module 4 is used to control the enrichment module 2, and when the aqueous solution to be tested meets the detection conditions, the aqueous solution to be tested desorbed after enrichment is transported to the trace zinc ion detection module 3; the main control module 4 is used to control the trace zinc ion detection module 3 to perform detection.

[0006] In the embodiment of the present application, the solution is automatically sampled through intelligent control, automatically enriched through an enrichment column after pretreatment, and then enters a detection device for automatic online detection. This solves the problems of low sensitivity, complex operation, and low detection efficiency of traditional detection methods, realizes automated monitoring, and has the technical effects of high sensitivity, high degree of automation, strong anti-interference ability, and low operating cost.

[0007] 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 digester 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, and the digestion unit 13 is connected to the enrichment module 2; the total organic carbon detection unit 12 is used to perform total organic carbon detection on 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 into 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 into the enrichment module 2; the digester sampling 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 and 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.

[0008] In the embodiment of the present application, the filtered aqueous solution to be tested is digested based on the total organic carbon detection results to eliminate the interference of organic matter in the detection of trace zinc ions.

[0009] In one embodiment, the sample sampling unit 11 includes a filter assembly 111 , a first syringe 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 syringe pump 112; the first syringe 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; The two detection probes of the pressure difference sensor 113 are respectively arranged on the front and rear sides of the filter membrane 114 of the filter component 111; the pressure difference sensor 113 is connected to the main control module 4, and the pressure difference sensor 113 is used to detect the pressure difference of the aqueous solution to be tested before and after passing through the filter component 111, and generate a pressure difference detection signal to be sent to the main control module 4; when the main control module 4 obtains a pressure difference value greater than a preset pressure difference threshold based on the pressure difference detection signal, it prompts to replace the filter component.

[0010] 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, and the second heat exchange tube 131b is 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 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.

[0011] In this embodiment of the present 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, filtered and digested aqueous solution to be tested enters the enrichment module 2 through the first flow control valve 51.

[0012] In one embodiment, the enrichment module 2 includes a balance adjustment unit 21, an enrichment unit 22, and a desorbent injection unit 23; The balance regulating unit 21 is connected to the enrichment unit 22 through the third flow path control valve 53; the balance regulating unit 21 is used to balance the aqueous solution to be tested after filtration and digestion, and then input it into the enrichment unit 22; The enrichment unit 22 is connected to the trace zinc ion detection module 3 through the fourth flow control valve 54; the enrichment unit 22 is used to enrich and desorb the zinc ions in the digested aqueous solution to be tested, and input the desorbed aqueous solution to be tested into the trace zinc ion detection module 3; the desorbent injection unit 23 is connected to the enrichment unit 22 through the third flow control valve 53.

[0013] 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 control the switching of the flow path of the third flow path control valve 53 according to the first signal; the main control module 4 is also used to receive a second signal sent by the enrichment unit 22, and control the switching of the flow path of the third flow path control valve 53 according to the second signal; the main control module 4 is also used to receive a third signal sent by the enrichment unit 22, and control the switching of the flow path of the fourth flow path control valve 54 according to the third signal, wherein the first signal is used to indicate that the balance adjustment unit 21 completes the balance adjustment operation; the second signal is used to indicate that the enrichment unit 22 completes the enrichment operation; and the third signal is used to indicate that the enrichment unit 22 completes the digestion operation.

[0014] In an embodiment of the present application, the balance adjustment unit 21 adjusts the pH value of the filtered and digested aqueous solution to adjust the balance of the filtered and digested aqueous solution to reduce the negative impact of the pH value of the filtered aqueous solution on the enrichment process of the enrichment unit 22 after digestion by the digester, thereby reducing the impact of the enrichment rate.

[0015] 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; One end of the pressure sensor 221 is connected to the balance adjustment unit 21 through the third flow 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 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 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 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, and 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 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, the 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 for enrichment and desorption respectively.

[0016] In the embodiment of the present application, the sample is injected by dual control of pressure and volume, which effectively reduces the system resistance, and can dynamically switch the single and double column flow paths through automatic control of pressure feedback to meet the flow requirements of different enrichment multiples of trace zinc ions in the solution, thereby improving the enrichment efficiency and the precision of the system.

[0017] In one embodiment, the system further comprises a trace zinc ion detection module 3 including a pH adjustment unit 31 and a trace zinc ion detection unit 32; The pH value adjustment unit 31 is connected to the enrichment module 2 through the fourth flow path control valve 54; the pH value adjustment unit 31 is connected to the trace zinc ion detection unit 32; the pH value adjustment unit 31 is used to adjust the pH value of the aqueous solution to be tested after desorption and input it into the trace zinc ion detection unit 32 for zinc ion detection; The pH value adjustment unit 31 includes a second valve generator 311 and a fifth injection pump 312; one end of the fifth injection pump 312 is connected to the second valve generator 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 generator 311 to release the buffer solution, and adjusts the pH value of the desorbed aqueous solution to be tested input into the second valve generator 311; the main control module 4 is used to control the fifth injection pump 312 to input the pH-adjusted aqueous solution to be tested into the trace zinc ion detection unit 32.

[0018] In the embodiment of the present application, since different zinc ion detection methods have different corresponding pH value requirements, corresponding buffer solution is released according to different zinc ion detection methods, and the pH value of the desorbed aqueous solution to be tested input into the second valve generating device 311 is adjusted to meet the pH value requirement of the zinc ion detection method in a specific application scenario, thereby improving the accuracy of zinc ion detection.

[0019] 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 one-way valve 62 and a second peristaltic pump 63; One liquid inlet of the waste liquid collection device 61 is connected to the enrichment unit 22 through the fourth flow path control valve 54; another liquid 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 turn; the main control module 4 is used to control the switching of the fourth flow path control valve 54.

[0020] In the embodiment of the present application, by providing a waste liquid collection device 61, the enrichment unit 22 can input the aqueous solution in 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, so that after the enrichment operation, the aqueous solution to be tested with a significantly decreased zinc ion content leaves the first enrichment column 222 and the second enrichment column 224, and the aqueous solution to be tested with a higher zinc ion content can be input from the balance adjustment unit 21 to the first enrichment column 222 and the second enrichment column 224, thereby improving the enrichment efficiency. In addition, 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.

[0021] In one embodiment, the system further includes a cleaning agent injection unit 7 ; the cleaning agent injection unit 7 includes a cleaning agent reagent storage device 71 , a sixth injection pump 72 , a fifth one-way valve 73 , a seventh injection pump 74 and a sixth one-way valve 75 .

[0022] One end of the sixth injection pump 72 is connected to the cleaning agent reagent 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 control valve 53 in sequence; one end of the seventh injection pump 74 is connected to the cleaning agent reagent 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.

[0023] 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 reagent storage device 71 into the enrichment unit 22 through the fifth one-way valve 73 and the third flow control valve 53, and control the seventh injection pump 74 to input the cleaning agent in the cleaning agent reagent storage device 71 into the pH adjustment unit 31 through the sixth one-way valve 75.

[0024] In the embodiment of the present application, after the detection of trace zinc ions is completed, the main control module 4 sends a corresponding control signal to the sixth syringe pump 72 and the seventh syringe pump 74, controlling the sixth syringe pump 72 and the seventh syringe pump 74 to start working, and the sixth syringe pump 72 drives the cleaning solution stored in the cleaning agent reagent storage device 71 to flow through the fifth one-way valve 73 and the first flow path control valve 51 to the enrichment unit 22 at a rate of 10 mL / min 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 neutrality, ensuring the regeneration availability of the enrichment unit 22. The seventh syringe pump 74 drives the cleaning solution stored in the cleaning agent reagent 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.

[0025] In a second aspect, the present application discloses an online monitoring method for trace zinc ions in an aqueous solution using the online monitoring system for trace zinc ions in the first aspect, comprising the steps of: 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, obtains a total organic carbon detection signal, and sends 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 and processing module 1 to transport the filtered water solution to be tested 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 water solution to be tested, and transport the digested water solution to be tested to the enrichment module 2; The enrichment module 2 enriches the input aqueous solution to be tested for trace zinc ions, and the main control module 4 controls the enrichment module 2. When the aqueous solution to be tested meets the detection conditions, the aqueous solution to be tested desorbed after enrichment is transported to the trace zinc ion detection module 3, and the main control module 4 controls the trace zinc ion detection module 3 to perform trace zinc ion detection.

[0026] In an embodiment of the present application, a system and method for online monitoring of trace zinc ions in an aqueous solution are provided, which solve 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 has the characteristics of high sensitivity, high degree of automation, strong anti-interference ability, and low operating cost.

[0027] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1A schematic structural diagram of an online monitoring system for trace zinc ions in an aqueous solution provided in one embodiment of the present application; Figure 2 A schematic structural diagram of an online monitoring system for trace zinc ions in an aqueous solution provided by another embodiment of the present application; Figure 3 A schematic flow chart of an online monitoring method for trace zinc ions in an aqueous solution provided in an online monitoring system for trace zinc ions provided in one embodiment of the present application. DETAILED DESCRIPTION

[0029] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0030] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. As used in this application and the appended claims, the singular forms "a," "an," "the," and "the" are 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 encompasses any and all possible combinations of one or more of the associated listed items.

[0031] 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 each other. 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 words "if" / "if" as used herein may be interpreted as "at the time of" or "when" or "in response to a determination."

[0032] See also Figure 1 , Figure 1 A schematic structural diagram of an online monitoring system for trace zinc ions in an aqueous solution provided in one embodiment of the present application.

[0033] In an embodiment of the present application, an online monitoring system for trace zinc ions in an 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.

[0034] The sampling and processing module 1 is connected to the enrichment module 2; the sampling and processing module 1 is used to filter the aqueous solution to be tested, and perform total organic carbon detection on 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 into 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 into the enrichment module 2.

[0035] The enrichment module 2 is connected to the trace zinc ion detection module 3. The enrichment module 2 is used to enrich the trace zinc ions in the input aqueous solution to be tested, and to transport the enriched aqueous solution to be tested to the trace zinc ion detection module 3.

[0036] The trace zinc ion detection module 3 is used to detect trace zinc ions in the enriched aqueous solution to be tested.

[0037] 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 aqueous solution to be tested or transport the aqueous solution to be tested to the enrichment module 2; the main control module 4 is used to control the enrichment module 2, and when the aqueous solution to be tested meets the detection conditions, the aqueous solution to be tested desorbed after enrichment is transported to the trace zinc ion detection module 3; the main control module 4 is used to control the trace zinc ion detection module 3 to perform detection.

[0038] Specifically, the main control module 4 is a microcontroller or microcontroller chip used to receive, transmit, and analyze signals. The main control module 4 is used to receive the total organic carbon detection signal sent by the sampling and processing module 1, analyze the total organic carbon detection signal, obtain the total organic carbon detection result, and generate a corresponding control signal based on the total organic carbon detection result to control the sampling and processing module 1 to digest the test aqueous solution or transport the test aqueous solution to the enrichment module 2. When the test aqueous solution meets the detection conditions, 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.

[0039] In an embodiment of the present application, 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 a total organic carbon detection signal, and sends it to the main control module 4 for analysis to obtain a total organic carbon value; when the total organic carbon value is less than or equal to a preset total organic carbon threshold value, specifically, the total organic carbon threshold value is set to 10 mg / L, the main control module 4 determines that the filtered aqueous solution to be tested meets the enrichment requirement, 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 value, the main control module 4 determines that the filtered aqueous solution to be tested does not meet the enrichment requirement, and the main control module 4 controls the sampling and processing module 1 to digest the aqueous solution to be tested and input it into the enrichment module 2 to eliminate the interference of organic matter during the detection of trace zinc ions.

[0040] The enrichment module 2 enriches the input aqueous solution to be tested for trace zinc ions. When the aqueous solution to be tested meets the detection conditions, specifically, the detection conditions can be a preset enrichment time to ensure the zinc ion enrichment effect in the solution, the main control module 4 controls the enrichment module 2 to transport the aqueous solution to be tested desorbed after enrichment to the trace zinc ion detection module 3, and the main control module 4 controls the trace zinc ion detection module 3 to perform trace zinc ion detection.

[0041] See also 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 digester injection unit 14 .

[0042] 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 .

[0043] 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, and the digestion unit 13 is connected to the enrichment module 2; the total organic carbon detection unit 12 is used to perform total organic carbon detection on 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 into 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 into the enrichment module 2; the digestant injection unit 14 is connected to the digestion unit 13 through the second flow path control valve 52.

[0044] The main control module 4 is connected to the total organic carbon detection unit 12 and 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.

[0045] Specifically, the sample sampling unit 11 filters the inputted aqueous solution to be tested, wherein the pH value of the aqueous solution to be tested is between 6 and 9, and is adjusted using 0.1 mol / L HNO3 and 0.1 mol / L NH3•H2O solutions.

[0046] The total organic carbon (TOC) detection unit 12 uses a visible light spectrophotometer (UV-vis) for initial detection. It performs TOC detection and signal generation on the filtered aqueous solution at a preset wavelength, specifically 254 nm, for 5 minutes. The resulting TOC detection signal is sent to the main control module 4. The main control module 4 analyzes the TOC detection signal to obtain a 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. The TOC detection unit 12 then feeds the filtered aqueous solution to be tested into the enrichment module 2.

[0047] If the total organic carbon value TOC>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 open 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 aqueous solution to be tested 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.

[0048] Most natural organic matter (such as humic acid and fulvic acid) and synthetic organic matter (such as surfactants and chelating agents) have strong absorption in the 254nm UV band, while inorganic carbon (such as CO3²⁻ and HCO3⁻) has no absorption at this wavelength. Selecting 254nm avoids interference from inorganic carbon and specifically captures only the total amount of organic matter in the water sample, ensuring that the total organic carbon (TOC) value truly reflects the degree of organic contamination. Furthermore, 254nm, belonging to the low-wavelength UV band, is sensitive to the absorption signals of low-concentration organic matter and can accurately distinguish between a TOC value of 5mg / L and a TOC value of 15mg / L, providing sufficient signal resolution for determining the 10mg / L threshold. Selecting a higher wavelength (such as 365nm) reduces the absorption intensity of organic matter, making the low TOC value signal easily obscured by noise, potentially causing the diversion logic to fail.

[0049] There may be local uneven distribution of organic matter in the water sample (such as suspended tiny organic particles), and short-term detection (such as 1 minute) may lead to misjudgment of the total organic carbon value TOC due to deviations at the moment of sampling (such as actual TOC = 8 mg / L, but it is detected as 12 mg / L due to instantaneous particle interference). 5 minutes of continuous detection can eliminate such fluctuations by signal averaging (such as taking a stable mean within 5 minutes) to ensure that the total organic carbon value TOC truly reflects the organic matter level of the entire water sample. Moreover, the online monitoring of trace zinc ions in the embodiment of the present application requires a fast response, and the 5-minute duration will not significantly extend the pre-treatment cycle while ensuring signal stability. If the detection time is too short (such as the detection time is less than 3 minutes), the signal stability is insufficient; if it is too long (such as the detection time is greater than 10 minutes), the overall monitoring efficiency will be reduced, especially affecting the processing capacity during batch sample analysis.

[0050] When TOC is ≤10 mg / L, the proportion of organic matter in the water sample that forms complexes with zinc ions is typically less than 5%, with free Zn²⁺ dominating. Direct digestion into the enrichment module allows for efficient capture, keeping detection error within 5%. However, when TOC exceeds 10 mg / L, the proportion of organically bound zinc may rise to over 30%. Without digestion, zinc ion recovery will significantly decrease (e.g., from 95% to 60%). The 10 mg / L threshold is based on the "acceptable level of organic interference." Furthermore, to avoid excessive digestion and reduce contamination risks, digestion processes (such as UV oxidation and microwave digestion) may introduce exogenous contamination (e.g., trace zinc dissolved from the digestion tank or impurities in the reagents). Skipping digestion when TOC is ≤10 mg / L can reduce the risk of such contamination. Digestion is performed only on samples with high TOC values, minimizing additional error while controlling interference.

[0051] In general, the 5-minute detection at a wavelength of 254nm and the 10mg / L threshold are set. The three form a complete logical chain, providing specific sensitive signals and ensuring the true and reliable detection of signals. For low-pollution water samples (total organic carbon value TOC ≤ 10mg / L), they can quickly pass through the enrichment module, shortening the process, reducing pollution, and ensuring detection efficiency; for highly polluted water samples (total organic carbon value TOC> 10mg / L), they are forced to enter the digestion module to completely eliminate organic interference and ensure detection accuracy.

[0052] In the embodiment of the present application, the aqueous solution to be tested is automatically sampled through intelligent control, automatically enriched through an enrichment column after pretreatment, and then enters the detection device for automatic online detection after enrichment, which solves the problems of low sensitivity, complex operation and low detection efficiency of traditional detection methods, realizes automated monitoring, and has the technical effects of high sensitivity, high degree of automation, strong anti-interference ability and low operating cost.

[0053] In one embodiment, the sample sampling unit 11 includes a filter assembly 111 , a first syringe pump 112 , and a differential pressure sensor 113 .

[0054] 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 .

[0055] Specifically, the main control module 4 generates a corresponding control signal and sends it to the first syringe pump 112, controlling the first syringe pump 112 to drive the aqueous solution to be tested into the filter component 111 at a rate of 5 to 30 mL / min, and the suspended particulate matter in the aqueous solution to be tested is filtered through the filter membrane in the filter component 111, and the filtered aqueous solution to be tested is input into the total organic carbon detection unit 12 to eliminate the interference of suspended particulate matter in the aqueous solution to be tested during the total organic carbon detection. The filter mesh can be made of nylon, polyvinylidene fluoride, polyethylene, mixed cellulose or polyethersulfone, and the pore size of the filter membrane can be selected to be 1 to 2 μm.

[0056] The 5-30 mL / min pumping rate balances filtration efficiency and effectiveness, adapting to the characteristics of different water samples. Specifically, for low-turbidity 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 filtration of a sufficient amount of water in 1-2 minutes, shortening pretreatment time and meeting the rapid response requirements of online monitoring. For medium- to high-turbidity samples (such as untreated industrial wastewater and contaminated groundwater with suspended particulate matter concentrations of 10-50 mg / L), the flow rate can be lowered to 5-15 mL / min. This reduced flow rate reduces the accumulation of particles on the filter membrane surface, preventing rapid clogging of the filter pores and ensuring a continuous and stable filtration process. This adjustable speed design adapts to water samples of varying turbidity, avoiding clogging or inefficiency, and balancing efficiency and sustainability. Furthermore, trace zinc ions (typically in the μg / L range) may not be effectively filtered due to brief contact with the membrane surface at high flow rates (greater than 30 mL / min). Slow flow rates (less than 5 mL / min) prolong the sample's retention time in the filtration unit, increasing the risk of zinc ion adsorption by the container wall or membrane. By controlling contact efficiency within the 5-30 mL / min range, zinc ion adsorption loss can be kept below 2%, minimizing membrane adsorption interference and ensuring target recovery.

[0057] The 1-2μm filter membrane pore size can accurately remove interfering particulate matter, balancing filtration thoroughness and water sample permeability. Specifically, if suspended particulate matter with a diameter greater than 1μm in the water sample enters the total organic carbon detection unit 12 and enrichment module 2, it can cause errors in total organic carbon (TOC) detection or block the flow path of the total organic carbon detection unit 12 and enrichment module 2. The 1-2μm pore size can effectively intercept such particulate matter while allowing dissolved substances to pass through smoothly, ensuring that the water sample entering the total organic carbon detection unit 12 and enrichment module 2 is a "clear liquid phase." A smaller pore size (such as 0.45 μm) can intercept more particulates but significantly reduces the water sample permeation rate (perhaps a 50% drop in flow rate at the same pressure). It may also retain some colloidal organic matter (0.1-1 μm in diameter) bound to zinc ions, leading to lower TOC values ​​(because the colloidal organic matter is not included) and potentially misjudging the need for digestion. A pore size larger than 2 μm cannot effectively intercept key interfering particles of 1-2 μm. The choice of 1-2 μm strikes a balance between intercepting interference and ensuring permeability.

[0058] Therefore, the combination of 5-30 mL / min adjustable speed pumping and 1-2 μm pore size filter membrane forms a "dynamic adaptation, precise purification" pre-treatment mechanism, which flexibly adjusts the flow rate for water samples with different turbidity levels, avoiding blockage and reducing target loss; and intercepts key particulate matter through precise pore size, eliminating physical interference and the risk of subsequent unit contamination.

[0059] The two detection probes of the pressure difference sensor 113 are respectively arranged on the front and rear sides of the filter membrane 114 of the filter component 111; the pressure difference sensor 113 is connected to the main control module 4, and the pressure difference sensor 113 is used to detect the pressure difference of the aqueous solution to be tested before and after passing through the filter component 111, and generate a pressure difference detection signal to be sent to the main control module 4; when the main control module 4 obtains a pressure difference value greater than a preset pressure difference threshold based on the pressure difference detection signal, it prompts to replace the filter component.

[0060] Specifically, the pressure differential sensor generates a pressure differential detection signal and sends it to the main control module 4. The main control module 4 analyzes the obtained pressure differential detection signal. If the pressure differential value detected 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 for the operating status of the filter membrane 114.

[0061] During the filtration process, as suspended particles accumulate on the membrane surface, the membrane pores gradually become clogged, increasing filtration resistance and gradually raising the differential pressure across the membrane. For a 1-2μm pore size membrane, the differential pressure during normal filtration typically remains stable at 0.05-0.15 MPa (fluctuating with the turbidity of the water sample). When a critical mass of 1-2μm particles adheres to the membrane surface, the differential pressure rapidly exceeds 0.2 MPa. The 0.3 MPa setting provides a short response buffer (typically maintaining effective filtration for 3-5 minutes), ensuring timely alarms while avoiding false alarms caused by transient pressure fluctuations (such as the pulse at pump startup). If the filter membrane becomes excessively clogged (pressure differential > 0.3 MPa), the continued increase in pressure may cause micropores or tears in the membrane, allowing unfiltered particles to enter the total organic carbon detection unit or enrichment module, contaminating the detection cell optical path (impairing 254 nm detection accuracy) or clogging the enrichment module (reducing zinc ion enrichment efficiency). The 0.3 MPa threshold effectively terminates the filtration process, providing pressure protection for downstream precision units and reducing equipment failure rates. Furthermore, when the pressure differential exceeds 0.3 MPa, the membrane's filtration efficiency 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. Furthermore, traditional membrane replacement relies on regular manual inspections (e.g., every 24 hours). However, fluctuations in water sample turbidity can cause sudden membrane blockage within a few hours (e.g., in highly turbid industrial wastewater). Manual inspections are difficult to detect in real time, potentially causing system downtime and distorted test data. The 0.3MPa differential pressure alarm mechanism uses real-time monitoring by sensors and automatic judgment by the main control module to trigger an alarm immediately when the blockage is critical, allowing operators to replace the filter membrane only when necessary, reducing ineffective inspection costs.

[0062] Therefore, the 0.3 MPa pressure difference threshold, by precisely matching the filter membrane characteristics and monitoring the blockage status in real time, not only enables intelligent management of filter membrane maintenance, but also reduces detection errors and equipment losses caused by filtration failure from the source. It is a key parameter to ensure the stable operation of the entire monitoring system.

[0063] In one embodiment, the digester injection unit 14 includes a digester reagent storage device 141 and a second injection pump 142 .

[0064] The digester reagent storage device 141 is connected to the digestion unit 13 via the second injection pump 142 and the second flow 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 and input the digester in the digester reagent storage device 141 into the digestion unit 13, wherein the digester uses 0.1 mol / L dilute nitric acid.

[0065] Specifically, when the total organic carbon value (TOC) is greater than 10 mg / L, the main control module 4 controls the second flow control valve 52 to open the flow path between the digester injection unit 14 and the digestion unit 13. The main control module 4 controls the second syringe pump 142 to drive the digester in the digester injection unit 14 into the digestion unit 13 at a rate of 5 to 30 mL / min. The digester is digested with the filtered aqueous solution to eliminate the interference of organic matter during the detection of trace zinc ions. The digestion unit 13 inputs the filtered and digested aqueous solution to the enrichment module 2.

[0066] 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, and the second heat exchange tube 131b is wound around the outer wall of the first heat exchange tube 131a.

[0067] One end of the first heat exchange tube 131a is connected to the total organic carbon detection unit 12 through the first flow 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.

[0068] 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 tube with an outer diameter of 1.2 to 2.0 mm and a length of 3 to 15 m. Heat exchange tube 131 is used to preheat the sample liquid and cool the high-temperature digested liquid flowing out of digestion device 132. Digestion device 132 uses an electrically heated aluminum cylinder structure with heating rods and temperature probes embedded at both ends. The surface of the cylinder has spiral grooves that secure the polytetrafluoroethylene coil and is covered with insulating quartz wool.

[0069] The first heat exchange tube 131a is a spiral glass tube with an outer diameter of 4 to 8 mm. Due to the excellent thermal conductivity of glass, the spiral tube structure increases the contact area and contact time between the test solution and the external environment (or the high-temperature digestion solution in 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, fully preheating the test solution before entering the digestion device, reducing the heating load on the digestion device and shortening the time it takes 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 test solution in the system (combined with the initial pump speed of 5-30 mL / min), ensuring smooth liquid flow while maintaining structural stability within the pressure range of 0.01-0.6 MPa, preventing rupture due to excessive pressure. Furthermore, glass is chemically inert to most aqueous solutions (especially those containing acid or mildly corrosive components), minimizing reactions between the tube and the test solution and preventing the introduction of impurities that could interfere with subsequent testing.

[0070] 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 meters. PTFE is resistant to high and low temperatures (-200 to 260°C) and has excellent thermal conductivity. The 1.2 to 2.0 mm outer diameter, combined with a length of 3 to 15 meters, significantly increases the heat exchange area between the high-temperature digestion liquid and the test liquid within the first heat exchange tube. This allows for sufficient heat transfer from the digested high-temperature liquid to the preheated test liquid, achieving heat recovery and reducing system energy consumption. It also cools the high-temperature digestion liquid to an appropriate temperature (preventing excessive temperatures from damaging the subsequent enrichment module). Furthermore, PTFE is highly resistant to strong acids, strong bases, and organic solvents, making it suitable for handling corrosive substances that may be produced during the digestion reaction. Its flexible material facilitates wrapping around the outer wall of the first heat exchange tube, optimizing the heat exchange structure layout. Furthermore, the outer diameter size matches the flow rate of the digested liquid, which can not only ensure that the liquid flows stably in the tube, but also ensure that the cooling effect meets the requirements through an appropriate flow rate.

[0071] The digestion device 132 is provided 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, generate a temperature and pressure detection signal and send it to the main control module 4; the temperature and pressure controller (not shown) is used to receive the temperature and pressure control signal sent by the main control module 4, and control the temperature and pressure of the digestion device 132 so that the pressure and temperature are controllable within the ranges of 0.01 ~ 0.6 MPa and 30 ~ 220 ° C, respectively.

[0072] Different types of organic matter (such as humic acid and small-molecule organic matter) require different digestion conditions. A temperature range of 30–220°C covers requirements ranging from low-temperature, gentle digestion to high-temperature, intense oxidative digestion (for example, simple organic matter can be decomposed at relatively low temperatures, while complex, large-molecule organic matter requires temperatures exceeding 200°C). Pressure control of 0.01–0.6 MPa can be combined with temperature regulation (e.g., increasing pressure at high temperatures to prevent boiling of the liquid), ensuring efficient digestion reactions in a liquid environment, enhancing the thoroughness of organic matter decomposition, and reducing interference with subsequent trace zinc ion detection. Furthermore, real-time parameter monitoring and adjustment via a temperature and pressure detector and controller prevents risks such as damage to the device or liquid leakage caused by excessive temperature or pressure. Stable pressure and temperature conditions ensure reproducible digestion reactions, ensuring consistent processing across sample batches and improving the reliability of test results. Furthermore, the pressure and temperature ranges of 0.01~0.6MPa and 30~220℃ respectively can adapt to the optimal reaction conditions of different digesters (such as potassium persulfate, ozone, etc.), expanding the applicability of the system to different water quality samples (such as surface water, industrial wastewater, etc.).

[0073] The filtered aqueous solution to be tested flowing out of the total organic carbon detection unit 12 passes through the first flow path control valve 51 and the first heat exchange tube 131a in sequence and flows into the digestion device 132. The digester flowing out of the digester injection unit 14 passes through the second flow path control valve 52 and the first heat exchange tube 131a in sequence and flows into the digestion device 132. A digestion reaction is carried out for 5 to 30 minutes at a pressure and temperature range of 0.01 to 0.6 MPa and 30 to 220°C, respectively. The filtered and digested aqueous solution flows into the enrichment module 2 in sequence through the second heat exchange tube 131b and the first peristaltic pump 133.

[0074] In one embodiment, the enrichment module 2 includes a balance adjustment unit 21 , an enrichment unit 22 and a desorbent injection unit 23 .

[0075] The balance adjustment unit 21 is connected to the enrichment unit 22 through the third flow 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 into the enrichment unit 22 .

[0076] The enrichment unit 22 is connected to the trace zinc ion detection module 3 through the fourth flow control valve 54; the enrichment unit 22 is used to enrich and desorb the zinc ions in the digested aqueous solution to be tested, and input the desorbed aqueous solution to be tested into the trace zinc ion detection module 3; the desorbent injection unit 23 is connected to the enrichment unit 22 through the third flow control valve 53.

[0077] 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 control the switching of the flow path of the third flow path control valve 53 according to the first signal; the main control module 4 is also used to receive a second signal sent by the enrichment unit 22, and control the switching of the flow path of the third flow path control valve 53 according to the second signal; the main control module 4 is also used to receive a third signal sent by the enrichment unit 22, and control the switching of the flow path of the fourth flow path control valve 54 according to the third signal, wherein the first signal is used to indicate that the balance adjustment unit 21 completes the balance adjustment operation; the second signal is used to indicate that the enrichment unit 22 completes the enrichment operation; and the third signal is used to indicate that the enrichment unit 22 completes the digestion operation.

[0078] 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 .

[0079] 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 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 into the enrichment unit 22.

[0080] Specifically, the balance adjustment unit 21 includes a first valve generator 211, which stores an acetic acid-ammonium acetate buffer solution with a pH value of 5.0-5.5. Since the pH value of the filtered test aqueous solution after being digested by the digestion agent may have a negative impact on the enrichment process of the enrichment unit 22, reducing the enrichment rate, for this reason, for the filtered and digested test aqueous solution output from the digestion unit 13, the main control module 4 controls the balance adjustment unit 21 to balance the filtered and digested test aqueous solution with the acetic acid-ammonium acetate buffer solution and the filtered and digested test aqueous solution at a volume ratio of 1:10, so that the pH value of the filtered and digested test aqueous solution is between 3.0-5.0, meeting the enrichment pH value requirement.

[0081] After judging the balance adjustment, a first signal is sent to the main control module 4. The main control module 4 controls the switching of the third flow control valve 53 according to the first signal, 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 aqueous solution to be tested after the balance adjustment operation is completed is input into the enrichment unit 22 for enrichment operation.

[0082] For the filtered aqueous solution to be tested output from the total organic carbon detection unit 12, its pH value 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 closes the flow path between the desorbent injection unit 23 and the enrichment unit 22, so that the filtered aqueous solution to be tested is input into the enrichment unit 22 through the balance adjustment unit 21 for enrichment operation.

[0083] 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. At the same time, 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 in the desorbent reagent storage device 231 into the enrichment unit 22 at a rate of 1 to 2 mL / min for digestion. 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, and inputs the digested aqueous solution to be tested into the trace zinc ion detection module 3 for zinc ion detection. The desorbent is 0.5 to 2% dilute nitric acid.

[0084] Among them, the desorbent delivery rate of 1~2mL / min plays a key role in balancing efficiency and accuracy and improving automation reliability in the entire detection system by ensuring desorption efficiency, maintaining flow stability, adapting to trace detection needs and protecting equipment.

[0085] Specifically, a flow rate of 1-2 mL / min falls within the low, stable delivery range, allowing the desorbent to fully contact the adsorbent material (such as the resin or filler containing the target) in the enrichment unit 22, extending the contact time. This slow flow rate avoids localized incomplete reaction caused by rapid desorbent flushing, ensuring complete desorption of the enriched substances (such as zinc ions and related organic matter), reducing residual material and providing a more accurate sample matrix for subsequent trace zinc ion detection. Trace zinc ion detection requires extremely high sample concentration and stability. A flow rate of 1-2 mL / min controls the amount of desorbent used, avoiding excessive dilution of the post-desorption solution and ensuring that the target concentration remains within the sensitivity range of the detection module. A flow rate that is too fast may result in excessive desorbent usage and dilute the target; a flow rate that is too slow 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, ensuring both detection speed and accuracy.

[0086] Furthermore, a flow rate of 1-2 mL / min matches the overall flow path design of the digestion and enrichment units (e.g., the diameter and material of the glass spiral tube and polytetrafluoroethylene tubing mentioned above), reducing pressure fluctuations within the flow paths. At this rate, the desorbent flows smoothly through the pipeline, preventing sample loss or leaks at the connections due to turbulence or sudden pressure changes, ensuring that the desorbed solution enters the subsequent flow paths intact and stably. Furthermore, a low flow rate of 1-2 mL / min facilitates precise control of the entire process by the main control module 4, synergizing with other units (e.g., temperature and pressure control in the digestion unit and signal acquisition timing in the detection module), ensuring parameter alignment across all links and improving the overall automation and stability of the system. The enrichment unit and subsequent flow paths are typically constructed of corrosion-resistant materials such as polytetrafluoroethylene, but high flow rates can exacerbate pipe wear and connector degradation. A low flow rate of 1-2 mL / min reduces fluid erosion on the inner walls of the pipeline, extending its lifespan and reducing maintenance costs.

[0087] 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 .

[0088] One end of the pressure sensor 221 is connected to the balance adjustment unit 21 through the third flow 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 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 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 control valve 55 in sequence.

[0089] 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, and 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 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, the 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 for enrichment and desorption respectively.

[0090] Specifically, in order to improve the efficiency of enrichment and avoid excessive system resistance caused by excessive solution inflow, which affects the precision of the system, the pressure sensor 221 detects the flow path pressure in the enrichment unit 22 in real time and sends the generated pressure detection signal to the main control module 4; the main control module 4 analyzes the received pressure detection signal, and when the flow path pressure is less than or equal to the preset flow path pressure threshold, for example, when the flow path pressure is less than or equal to 2.80 MPa, the main control module 4 controls the fifth flow path control valve 55 to close, closing the flow path between the balance adjustment unit 21 and the second enrichment column 224, and the flow path between the desorbent injection unit 23 and the second enrichment column 224, so that enrichment and desorption are concentrated in the first enrichment column 222. When the flow path pressure is greater than the preset flow path pressure threshold, for example, when the flow path pressure is greater than 2.80 MPa, the main control module 4 controls the fifth flow path control valve 55 to open, opens the flow path between the balance adjustment unit 21 and the second enrichment column 224, and the flow path between the desorbent injection unit 23 and the second enrichment column 224, to form a diversion effect, so that the solution input into the enrichment unit 22 can flow into the second enrichment column 224 through the fifth flow path control valve 55 for enrichment and desorption. The injection is carried out by dual control of pressure and volume, which effectively reduces the system resistance, and can dynamically switch the single and double column flow paths through automatic control of pressure feedback to meet the flow 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 the unidirectional flow of the solution to avoid contamination caused by backflow.

[0091] Components involved in the system, such as piping (such as PTFE tubing), valves (fifth flow control valve 55), and enrichment columns (first enrichment column 222 and second enrichment column 224), all have upper pressure limits. The 2.8 MPa threshold is determined based on the material properties (such as the pressure resistance of PTFE) and structural strength of these components. This prevents hardware damage such as piping rupture and interface leakage caused by excessive pressure, while also ensuring flow path stability during normal enrichment and desorption processes.

[0092] 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 compound (trace zinc ions) onto the enrichment material. Excessively low pressure can result in slow flow rates, prolonging the enrichment time; excessively high pressure can lead to excessive flow resistance, reducing sufficient contact between the solution and the enrichment material, and even causing some solution to flow out without being effectively adsorbed. The 2.8 MPa threshold has been optimized to maintain enrichment efficiency during single-column operation (pressure ≤ 2.8 MPa) while providing a reasonable pressure buffer for dual-column flow splitting. The test solutions may vary in properties such as viscosity and suspended solids content. When the solution viscosity is high or the flow rate is high, the flow resistance increases significantly. The 2.8 MPa threshold serves as a critical point for determining whether a single column can handle the current flow rate. This ensures that the system automatically switches flow paths through pressure feedback when the solution properties fluctuate, preventing a decrease in enrichment efficiency due to insufficient flow adaptability.

[0093] In one embodiment, the trace zinc ion detection module 3 includes a pH value adjustment unit 31 and a trace zinc ion detection unit 32 .

[0094] The pH adjustment unit 31 is connected to the enrichment module 2 through the fourth flow 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 value of the aqueous solution to be tested after desorption, and input it into the trace zinc ion detection unit 32 for zinc ion detection.

[0095] The pH value adjustment unit 31 includes a second valve generator 311 and a fifth injection pump 312; one end of the fifth injection pump 312 is connected to the second valve generator 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 generator 311 to release the buffer solution, and adjusts the pH value of the desorbed aqueous solution to be tested input into the second valve generator 311; the main control module 4 is used to control the fifth injection pump 312 to input the pH-adjusted aqueous solution to be tested into the trace zinc ion detection unit 32.

[0096] Specifically, the method for trace zinc ion detection unit 32 to detect trace zinc ions can be spectroscopy (zinc reagent colorimetry), mass spectrometry (ICP-MS) or electrochemistry (potentiometric titration). Different zinc ion detection methods have different corresponding pH value requirements. The main control module 4 controls the second valve generator 311 to release the corresponding buffer solution according to the trace zinc ion detection method adopted by the trace zinc ion detection unit 32, and adjusts the pH value of the desorbed aqueous solution to be tested that is input from the enrichment unit 22 to the second valve generator 311. Specifically, if mass spectrometry is used, the pH value of the aqueous solution to be tested after desorption does not need to be adjusted; if the zinc reagent colorimetric method is used, the buffer solution uses a borate buffer with a pH value of 10.5-11.5, and the volume ratio range of the borate buffer to the aqueous solution to be tested after desorption is [3, 4]. The pH value of the aqueous solution to be tested after desorption is adjusted to 8.8-9.0; if the potentiometric titration method is used, the buffer solution uses an ammonium acetate buffer with a pH value of 6.5-7.5, and the volume ratio range of the ammonium acetate buffer to the aqueous solution to be tested after desorption is [3, 4]. The pH value of the aqueous solution to be tested after desorption is adjusted to 6.5-7.5, so as to meet the pH value requirements of the zinc ion detection method in specific application scenarios and improve the accuracy of zinc ion detection.

[0097] 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 be tested into 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 a trace zinc ion detection result.

[0098] Please refer to Figure 2 , Figure 2 A schematic structural diagram of an online monitoring system for trace zinc ions in an aqueous solution provided in another embodiment of the present application.

[0099] 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 one-way valve 62 and a second peristaltic pump 63 .

[0100] One liquid 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 liquid 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 turn; 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.

[0101] Specifically, in order to further improve the enrichment effect of the enrichment unit, by providing a waste liquid collection device 61, the enrichment unit 22 can input the aqueous solution in 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. After the enrichment operation, the aqueous solution to be tested with a decreased zinc ion content leaves the first enrichment column 222 and the second enrichment column 224, and the aqueous solution to be tested with a higher zinc ion content can 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. In addition, 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.

[0102] In one embodiment, the system further includes a cleaning agent injection unit 7 ; the cleaning agent injection unit 7 includes a cleaning agent reagent storage device 71 , a sixth injection pump 72 , a fifth one-way valve 73 , a seventh injection pump 74 and a sixth one-way valve 75 .

[0103] One end of the sixth injection pump 72 is connected to the cleaning agent reagent 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 control valve 53 in sequence; one end of the seventh injection pump 74 is connected to the cleaning agent reagent 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.

[0104] 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 reagent storage device 71 into the enrichment unit 22 through the fifth one-way valve 73 and the third flow control valve 53, and control the seventh injection pump 74 to input the cleaning agent in the cleaning agent reagent storage device 71 into the pH adjustment unit 31 through the sixth one-way valve 75.

[0105] Specifically, after the trace zinc ion detection is completed, the main control module 4 sends a corresponding control signal to the sixth syringe pump 72 and the seventh syringe pump 74, controlling the sixth syringe pump 72 and the seventh syringe pump 74 to start working. The sixth syringe pump 72 drives the cleaning solution stored in the cleaning agent storage device 71 to flow through the fifth one-way valve 73 and the first flow control valve 51 to the enrichment unit 22 at a rate of 10 mL / min 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 flushed to neutrality (for 1 minute), ensuring the regeneration availability of the anion resin or chelating resin serving as the first enrichment column 222 and the second enrichment column 224. The seventh syringe 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.

[0106] In an optional embodiment, the flow path, each flow path control valve, each injection pump, and peristaltic pump constructed by the above system can be made of materials such as polytetrafluoroethylene or polyetheretherketone that are resistant to acid and alkali corrosion and have no metal pollution.

[0107] The syringe pump absorbs and delivers the solution in the liquid delivery system and can accurately control the solution volume and flow rate; the flow control valve is used to open and close and switch the flow path; the one-way valve is used to ensure the unidirectional flow of the solution to avoid backflow and contamination.

[0108] In an optional embodiment, the present application also discloses an online monitoring method for trace zinc ions in aqueous solution. Figure 3 , Figure 3 A schematic flow chart of an online monitoring method for trace zinc ions in an aqueous solution provided in an embodiment of the present application includes steps S1 to S3, as follows: 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, obtains a total organic carbon detection signal, and sends it to the main control module 4.

[0109] Total organic carbon is prone to produce carbon-based polyatomic ion interference, and high organic matter leads to matrix effects and cone pore blockage.

[0110] In an embodiment of the present application, the sample sampling unit 11 in the sampling processing module 1 is used to input the aqueous solution to be tested for sample sampling. The sample sampling unit 11 inputs the filtered aqueous solution to be tested into 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 to be tested at a preset wavelength, specifically a wavelength of 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, and the main control module 4 analyzes the obtained total organic carbon detection signal to obtain a total organic carbon value.

[0111] S2: The main control module 4 analyzes the total organic carbon detection signal obtained 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 aqueous solution to be tested 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 aqueous solution to be tested and transport the digested aqueous solution to be tested to the enrichment module 2.

[0112] In an embodiment of the present application, if the total organic carbon value TOC ≤ 10 mg / L, it means that the filtered aqueous solution to be tested meets the enrichment requirements, and 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 be tested into the balance adjustment unit 21.

[0113] If the total organic carbon value TOC>10 mg / L, it means that the filtered water solution to be tested 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 opens 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 water solution to be tested into the digestion unit 13 for digestion treatment to meet the enrichment requirements.

[0114] 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 timely input the digester into the digestion unit 13, and react with the filtered aqueous solution to be tested in a timely manner, thereby improving the operating efficiency of the device.

[0115] After the flow path is opened, the total organic carbon detection unit 12 inputs the filtered aqueous solution to be tested into the digestion unit 13 for digestion, and the digestion unit 13 inputs the filtered and digested aqueous solution to be tested into the balance adjustment unit 21. Since the pH value of the filtered aqueous solution to be tested may have a negative impact on the enrichment process of the enrichment unit 22 after digestion, the main control module 4 controls the balance adjustment unit 21 to adjust the pH value of the filtered and digested aqueous solution to be tested, so that the pH value of the filtered and digested aqueous solution to be tested meets the pH value requirement of enrichment, and the pH-adjusted aqueous solution to be tested is input into the enrichment unit 22 for enrichment and desorption, thereby improving the enrichment and desorption efficiency.

[0116] S3: The enrichment module 2 enriches the input aqueous solution to be tested for trace zinc ions, and the main control module 4 controls the enrichment module 2. When the aqueous solution to be tested meets the detection conditions, the aqueous solution to be tested desorbed after enrichment is transported to the trace zinc ion detection module 3, and the main control module 4 controls the trace zinc ion detection module 3 to perform trace zinc ion detection.

[0117] In the embodiment of the present application, since different zinc ion detection methods have different pH value requirements, in order to meet the pH value requirements of the zinc ion detection method and improve the accuracy of zinc ion detection, the main control module 4 controls the pH value adjustment unit 31 to adjust the pH value of the desorbed aqueous solution to be tested according to the trace zinc ion detection method adopted by the trace zinc ion detection unit 32, and inputs it into 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 parses the obtained trace zinc ion detection signal to obtain a trace zinc ion detection result.

[0118] Specifically, when the zinc ion detection method adopts mass spectrometry, the main control module 4 determines that it is not necessary to adjust the pH value of the aqueous solution to be tested after desorption.

[0119] 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 aqueous solution to 8.8-9.0, wherein the second buffer solution adopts 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 aqueous solution to be tested is in the range of [3, 4].

[0120] When the zinc ion detection method adopts the potentiometric titration method, the main control module 4 controls the pH adjustment unit to release the third buffer solution to adjust the pH value of the desorbed aqueous solution to 5.5, wherein the third buffer solution adopts 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 aqueous solution to be tested is in the range of [3, 4].

[0121] In the embodiments of the present application, the solution is automatically sampled through intelligent control, automatically enriched through an enrichment column after pretreatment, and then enters a detection device for automatic online detection after enrichment, which solves the problems of low sensitivity, complex operation, and low detection efficiency of traditional detection methods, realizes automated monitoring, and has the technical effects of high sensitivity, high degree of automation, strong anti-interference ability, and low operating cost.

[0122] In an embodiment of the present application, a system and method for online monitoring of trace zinc ions in an aqueous solution are provided, which solve 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 has the characteristics of high sensitivity, high degree of automation, strong anti-interference ability, and low operating cost.

[0123] The present invention is not limited to the above-mentioned embodiments. If various changes or modifications of the present invention do not depart from the spirit and scope of the present invention, and if these changes and modifications fall within the scope of the claims of the present invention and equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. An online monitoring system for trace zinc ions in aqueous solution, characterized in that: include: Sampling and processing module (1), enrichment module (2), trace zinc ion detection module (3) and main control module (4); The sampling and processing module (1) is connected to the enrichment module (2); the sampling and processing module (1) is used to filter the aqueous solution to be tested, and perform total organic carbon detection on the filtered aqueous solution to be tested; when the total organic carbon value is less than or equal to a preset total organic carbon threshold, the filtered aqueous solution to be tested is input into 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 into the enrichment module (2); The enrichment module (2) is in communication with the trace zinc ion detection module (3), and the enrichment module (2) is used to enrich the trace zinc ions in the input aqueous solution to be tested, and to transport the enriched aqueous solution to be tested to the trace zinc ion detection module (3); 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 based on the total organic carbon detection result, 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); the main control module (4) is used to control the enrichment module (2) to transport the aqueous solution to be tested that is desorbed after enrichment 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 on-line monitoring system for trace zinc ions in aqueous solution according to claim 1, wherein: The sampling and processing module (1) comprises a sample sampling unit (11), a total organic carbon detection unit (12), a digestion unit (13) and a digester injection unit (14); The sample sampling unit (11) is in communication with the total organic carbon detection unit (12), and 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 a first flow path control valve (51), and the digestion unit (13) is connected to the enrichment module (2); the total organic carbon detection unit (12) is used to perform total organic carbon detection on the filtered aqueous solution to be tested, and when the total organic carbon value is less than or equal to a preset total organic carbon threshold, the filtered aqueous solution to be tested is input into 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 into the enrichment module (2); the digestant injection unit (14) is connected to the digestion unit (13) through a second flow path control valve (52); The main control module (4) is connected to the total organic carbon detection unit (12), and the main control module (4) is used to receive a 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 on-line monitoring system for trace zinc ions in aqueous solution according to claim 2, wherein: The sample sampling unit (11) comprises a filter assembly (111), a first injection pump (112), and a differential pressure sensor (113); The filter assembly (111) is in communication with 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 a control signal from 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 pressure difference sensor (113) are respectively arranged on the front and rear sides of the filter membrane (114) of the filter assembly (111); the pressure difference sensor (113) is connected to the main control module (4), and the pressure difference 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 pressure difference detection signal to be sent to the main control module (4); when the pressure difference value obtained based on the pressure difference detection signal is greater than a preset pressure difference threshold, the main control module (4) prompts to replace the filter assembly.

4. The on-line monitoring system for trace zinc ions in aqueous solution according to claim 2, wherein: The digestion unit (13) comprises a heat exchange device (131), a digestion device (132), and a first peristaltic pump (133); the heat exchange device (131) comprises a first heat exchange tube (131a) and a second heat exchange tube (131b), and the second heat exchange tube (131b) is 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 on-line monitoring system for trace zinc ions in aqueous solution according to claim 1, characterized in that: 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) via a 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 into the enrichment unit (22); The enrichment unit (22) is connected to the trace zinc ion detection module (3) via a fourth flow path control valve (54); the enrichment unit (22) is used to enrich and desorb zinc ions in the digested aqueous solution to be tested, and input the desorbed aqueous solution to be tested into the trace zinc ion detection module (3); the desorbent injection unit (23) is connected to the enrichment unit (22) via a 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 control the switching of the flow path of the third flow path control valve (53) according to the first signal; the main control module (4) is also used to receive a second signal sent by the enrichment unit (22), and control the switching of the flow path of the third flow path control valve (53) according to the second signal; the main control module (4) is also used to receive a third signal sent by the enrichment unit (22), and control the switching of the flow path of the fourth flow path control valve (54) according to the third signal, 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; and the third signal is used to instruct the enrichment unit (22) to complete the digestion operation.

6. The on-line monitoring system for trace zinc ions in aqueous solution according to claim 5, characterized in that: 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); One end of the pressure sensor (221) is in communication with the balance adjustment unit (21) via the third flow path control valve (53); the other end of the pressure sensor (221) is in communication with one end of the first enrichment column (222), and the other end of the pressure sensor (221) is in communication with one end of the second enrichment column (224) via the fifth flow path control valve (55); the other end of the first enrichment column (222) is in communication with the trace zinc ion detection module (3) via 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 in communication with the trace zinc ion detection module (3) via 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, and when the flow path pressure is less than or equal to a 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 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, the 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) for enrichment and desorption.

7. The on-line monitoring system for trace zinc ions in aqueous solution according to claim 6, characterized in that: The trace zinc ion detection module (3) comprises a pH value adjustment unit (31) and a trace zinc ion detection unit (32); The pH value adjustment unit (31) is connected to the enrichment module (2) through the fourth flow path control valve (54); the pH value adjustment unit (31) is connected to the trace zinc ion detection unit (32); the pH value adjustment unit (31) is used to adjust the pH value of the aqueous solution to be tested after desorption, and input it into the trace zinc ion detection unit (32) for zinc ion detection; The pH value adjustment unit (31) includes a second on-valve generator (311) and a fifth injection pump (312); one end of the fifth injection pump (312) is connected to the second on-valve generator (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 on-valve generator (311) to release the buffer solution, and adjusts the pH value of the desorbed aqueous solution to be tested input into the second on-valve generator (311); the main control module (4) is used to control the fifth injection pump (312) to input the pH-adjusted aqueous solution to be tested into the trace zinc ion detection unit (32).

8. The on-line monitoring system for trace zinc ions in aqueous solution according to claim 7, characterized in that: The system further comprises a waste liquid collection unit (6); the waste liquid collection unit (6) comprises a waste liquid collection device (61), a fourth one-way valve (62) and a second peristaltic pump (63); One liquid inlet of the waste liquid collection device (61) is connected to the enrichment unit (22) through the fourth flow path control valve (54); another liquid 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).

9. The on-line monitoring system for trace zinc ions in aqueous solution according to claim 7, characterized in that: The system further comprises a cleaning agent injection unit (7); the cleaning agent injection unit (7) comprises a cleaning agent reagent storage device (71), a sixth injection pump (72), a fifth one-way valve (73), a seventh injection pump (74) and a sixth one-way valve (75); One end of the sixth injection pump (72) is in communication with the cleaning agent storage device (71), and the other end of the sixth injection pump (72) is in communication with the enrichment unit (22) through the fifth one-way valve (73) and the third flow control valve (53) in sequence; one end of the seventh injection pump (74) is in communication with the cleaning agent storage device (71), and the other end of the seventh injection pump (74) is in communication with the pH value adjustment unit (31) through the sixth one-way valve (75) and the three-way valve (33) in sequence; 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 reagent storage device (71) into the enrichment unit (22) through the fifth one-way valve (73) and the third flow control valve (53), and control the seventh injection pump (74) to input the cleaning agent in the cleaning agent reagent storage device (71) into the pH value adjustment unit (31) through the sixth one-way valve (75).

10. A method for online monitoring of trace zinc ions in an aqueous solution using the online monitoring system for trace zinc ions in an aqueous solution according to any one of claims 1 to 9, comprising the steps of: 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, obtains a total organic carbon detection signal, and sends it to the main control module (4); The main control module (4) analyzes the total organic carbon detection signal obtained to obtain a total organic carbon value; when the total organic carbon value is less than or equal to a preset total organic carbon threshold, the main control module (4) controls the sampling and processing module (1) to transport the filtered aqueous solution to be tested 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 aqueous solution to be tested, and transports the digested aqueous solution to be tested to the enrichment module (2); The enrichment module (2) enriches the input aqueous solution to be tested for trace zinc ions. When the aqueous solution to be tested meets the detection conditions, the main control module (4) controls the enrichment module (2) to transport the aqueous solution to be tested desorbed after enrichment 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.

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