Full-automatic chemical oxygen demand analyzer and method based on mercury-free high-silver digestion

Abstract

The invention provides a full-automatic chemical oxygen demand analyzer and method based on mercury-free high-silver digestion, and relates to the technical field of water quality analysis and testing. The analyzer comprises a sample disc module, a multi-axis cooperation module, a liquid adding module, a digestion module, a detection module, a magneton putting module and a computer control and data processing module. The analyzer realizes automatic liquid adding, digestion and titration detection of a sample through a mercury-free high-silver catalytic closed digestion system and full-process automatic control, has the characteristics of environmental protection, high efficiency, energy conservation, high detection precision and simplicity and convenience in operation, remarkably reduces the mercury pollution risk, shortens the analysis period, and improves the stability and applicability of high-chlorine water sample detection.

Description

Technical Field

[0001] This invention relates to the field of water quality analysis and testing technology, and in particular to a fully automated chemical oxygen demand analyzer and method based on mercury-free high-silver digestion. Background Technology

[0002] Chemical oxygen demand (COD), a key indicator for measuring the degree of water pollution by reducing substances, is widely used in river pollution research, industrial wastewater studies, and the operation and management of wastewater treatment plants. Its value reflects the amount of reducing substances oxidized by oxidants in a water sample, which is then converted into the corresponding oxygen concentration. It is an important comprehensive indicator of the relative content of organic matter. Under the background of total quantity control in environmental protection and water quality management, accurate measurement of COD is an essential control measure for wastewater treatment and discharge, as well as for many industrial sectors. Whether it's rivers and lakes serving as drinking water sources or marine resource development, all rely on precise monitoring of water COD.

[0003] Currently, existing standard methods for determining chemical oxygen demand (COD) using potassium dichromate all involve oxidizing and digesting the organic matter in the sample in a sulfuric acid medium at a specific temperature, and then measuring the remaining potassium dichromate using appropriate methods to calculate the COD value. However, these standard methods generally have some problems: the need to eliminate chloride ions (Cl-) from the water sample... - To mitigate interference, mercury salt complexation is used in many methods, leading to the use of large quantities of highly toxic mercury salts. Mercury and mercury compounds are listed by the United Nations as one of the first batch of toxic and hazardous water pollutants, classified as severe pollutants. The indiscriminate discharge of mercury-containing wastewater will severely pollute the human environment, and mercury recovery and treatment processes are complex and require significant social resources. Discharging the measured wastewater into sewage pipes or rivers will cause immense environmental harm. Furthermore, for some high-chlorine samples, potassium permanganate is used as an oxidant to avoid excessive use of mercury salts, as described in HJ / T132-2003 "Determination of Chemical Oxygen Demand in High-Chlorine Wastewater - Potassium Iodide Alkaline Potassium Permanganate Method." However, due to the weak oxidizing power of potassium permanganate under alkaline conditions, the measured results are significantly lower than expected. To ensure comparability, this method requires re-measurement using HJ828-2017 and comparison of results to obtain a correction coefficient, which is cumbersome and results in poor measurement accuracy.

[0004] Furthermore, traditional manual methods, besides using strong acids, strong oxidants, and toxic and harmful chemical reagents, also suffer from problems such as cumbersome operation, long experimental time, and difficulty in mastering the detection techniques, requiring experienced operators to ensure accurate measurements. In conclusion, developing a mercury-free, efficient, accurate, and automated method and device for determining chemical oxygen demand (COD) has become a critical issue urgently needing to be addressed in the field of water quality testing. This is not only an urgent requirement of the environmental protection industry but also a significant technological upgrade for the water quality monitoring industry, and is of great importance to promoting the development of environmental protection. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a fully automated chemical oxygen demand (COD) analyzer and method based on mercury-free high-silver digestion. Through a closed digestion system with mercury-free high-silver catalysis and fully automated control of the process, COD analysis is achieved in a green, environmentally friendly, energy-efficient, high-precision, and easy-to-operate manner. This significantly eliminates the risk of mercury pollution, shortens the analysis cycle, and improves the stability and applicability of high-chlorine water sample detection.

[0006] To achieve the above objectives, the present invention provides the following solution: A fully automated chemical oxygen demand analyzer based on mercury-free high-silver digestion includes: a sample tray module, a multi-axis collaborative module, a liquid addition module, a digestion module, a detection module, a magnetic particle delivery module, and a computer control and data processing module; The sample tray module is used to place the capped digestion tube; the multi-axis collaborative module is used to grasp the capped digestion tube and transfer it between the sample tray module, the liquid addition module, and the digestion module; the liquid addition module is used to add reagents into the capped digestion tube; the digestion module is used to heat the capped digestion tube to complete mercury-free, high-silver, sealed digestion; the detection module, in collaboration with the magnetic dosing module and the liquid addition module, performs titration detection on the sample in the capped digestion tube; the computer control and data processing module is connected to the sample tray module, the multi-axis collaborative module, the liquid addition module, the digestion module, the detection module, and the magnetic dosing module, respectively, and collaboratively controls the entire sample detection process.

[0007] Preferably, the sample tray module includes a sample tray and a fan located on the right side of the sample tray. The fan is used to cool the digestion tube after digestion. The sample tray has a double-layer structure, and the sample hole of the sample tray has two concentric circular holes to enhance the stability of the digestion tube placement.

[0008] Preferably, the multi-axis collaborative module includes an x-axis movement module, a y-axis movement module, and a z-axis movement module; the x-axis movement module and the z-axis movement module include a motor, a slider, and a slide rail; the y-axis movement module includes a lead screw motor, a slider, and a rotary electro-servo electric gripper; the z-axis movement module is fixed on the slider of the x-axis movement module, and the y-axis movement module is fixed on the slider of the z-axis movement module, so that the rotary electro-servo electric gripper can achieve three-dimensional movement under computer control.

[0009] Preferably, the multi-axis collaborative module adopts a polar coordinate motion system to realize the three-dimensional spatial motion of the rotary electric servo gripper.

[0010] Preferably, the rotary electric servo gripper is used to grip the digestion tube with a cap, and the cap of the digestion tube is tightened or loosened by clamping and rotating.

[0011] Preferably, the liquid addition module includes several reagent pumps, a liquid addition arm assembly, a liquid addition point, and a waste discharge assembly; the liquid addition arm assembly has a reagent channel, and the reagent tubing of the reagent pump is fixed to the reagent channel of the liquid addition arm assembly; the liquid addition point is fixed directly in front of the liquid addition arm assembly, and the liquid addition arm assembly drives the liquid outlet to align with the digestion tube on the liquid addition point; the waste discharge assembly is located directly below the liquid addition arm assembly for reagent waste discharge.

[0012] Preferably, the liquid filling position includes a liquid filling tank and an electric gripper. The liquid filling tank has openings on both sides, and the electric gripper passes through the openings to clamp or release the digestion tube.

[0013] Preferably, the waste discharge assembly includes a waste discharge tank and a waste discharge peristaltic pump, the waste discharge tank and the waste discharge peristaltic pump being connected via an acid-resistant rubber tube; the waste discharge pump is connected to a silver halide waste liquid recovery device.

[0014] Preferably, the digestion module includes a plurality of graphite digestion holes, a heating plate and a temperature controller; the heating plate is located below the graphite digestion holes and provides a heat source, and the temperature controller is used for temperature control; depending on the type of test sample, the heating temperature range is 50℃ to 300℃ and the heating time range is 10min to 120min.

[0015] A method for determining the chemical oxygen demand (COD) of high-chlorine water samples using the aforementioned fully automated COD analyzer based on mercury-free high-silver digestion includes: Place a capped digestion tube on the sample tray module; The multi-axis collaborative module grabs the covered digestion tube to the liquid filling position, and the rotary electro-servo electric gripper loosens or tightens the digestion tube cap. The reagents are added sequentially to the digestion tube by the liquid addition module according to the set program. After tightening the tube cap, the tube is transferred to the digestion module for heating and digestion. After digestion, cool the sample and move it to the detection position to open the lid; A magnetic particle is introduced into the digestion tube by the magnetic particle dispensing module, pure water and indicator are added by the liquid addition module, and the stirring component is started to mix. Ferrous ammonium sulfate is added dropwise by the liquid addition module, and the color sensor of the detection module monitors the color change of the solution in real time and completes the titration. The computer control and data processing module is used to collect detection data and calculate the chemical oxygen demand (COD) results.

[0016] The present invention discloses the following technical effects: 1. Green and environmentally friendly, eliminating the risk of mercury pollution. This invention abandons traditional mercury-containing reagents and uses mercury-free reagents combined with high-silver catalysts to construct a digestion system. This avoids the use of highly toxic mercury salts and the problem of mercury pollution in subsequent waste liquid treatment from the source, which meets the urgent needs of the environmental protection industry for "green testing" and significantly reduces the harm to the ecological environment and the health of operators.

[0017] 2. Improved digestion efficiency and shorter analysis cycle Based on the closed digestion design and the strong catalytic effect of the high-silver catalyst, this invention can reduce the sample digestion time from 2 hours in traditional methods to 30 minutes, improving efficiency by approximately 4 times. Simultaneously, through fully automated integration (automatic sample addition, digestion, cooling, and detection), the complete analysis cycle for a single batch of samples is shortened from 8 hours in traditional manual operation to less than 3 hours, significantly improving batch detection capabilities and meeting the needs of emergency monitoring and high-frequency testing.

[0018] 3. High detection accuracy and strong anti-interference ability This invention uses a color sensor to simulate the human eye in real time monitoring color changes during titration. The titration results are then combined with automatic computer calculations, thus avoiding visual errors associated with manual titration.

[0019] 4. Fully automated process, reducing the operational threshold. The multi-axis collaborative module enables automatic transfer of digestion tubes between units, the liquid addition module precisely controls the amount of reagent added, the magnetic dosing and stirring module ensures uniform solution mixing, and the computer system controls the entire process and processes data without human intervention. Operators only need to place the sample to automatically complete the entire process from digestion to detection, solving the problems of traditional methods that rely on experienced personnel and are cumbersome, and reducing human error.

[0020] 5. Wide range of applications and strong adaptability This invention is adaptable to high-chlorine water samples with chlorine concentrations ranging from 0 to 20000 mg / L, eliminating the need to change the detection method due to differences in chlorine concentration. Furthermore, the sample tray module can accommodate multiple sample trays, supporting batch detection and cyclic sampling. It meets the detection needs of different scenarios, providing an efficient solution for the analysis of chemical oxygen demand (COD) in high-chlorine water samples. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A front view of the analyzer provided in an embodiment of the present invention; Figure 2 A top view of the analyzer provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of a magnetic particle delivery module provided in an embodiment of the present invention.

[0023] Explanation of reference numerals in the attached figures: 1. Sample tray module; 2. Multi-axis collaborative module; 3. Liquid addition module; 4. Digestion module; 5. Detection module; 6. Magnetic particle delivery module; 61. Motor; 62. Magnetic particle slot; 63. Magnetic particle wheel slot; 64. Guide block. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The purpose of this invention is to provide a fully automated chemical oxygen demand (COD) analyzer and method based on mercury-free high-silver digestion. Through the collaborative design of mercury-free high-silver closed digestion and full-process automation, it achieves high-precision, rapid, and environmentally friendly detection of COD in high-chlorine water samples. It has comprehensive advantages such as being green and mercury-free, improving efficiency, having strong anti-interference capabilities, and being intelligent in operation, which significantly improves the safety and reliability of water quality monitoring.

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] like Figures 1 to 3As shown, the fully automated chemical oxygen demand (COD) analyzer based on mercury-free high-silver digestion provided by this invention can realize automatic reagent addition, automatic digestion, and automatic detection, achieving fully automated green detection of high-chlorine water samples. It is easy to operate, highly automated, and provides accurate detection results. The analyzer includes a sample tray module 1, a multi-axis collaborative module 2, a liquid addition module 3, a digestion module 4, a detection module 5, a magnetic particle delivery module 6, and a computer control and data processing module 7.

[0028] The sample tray module 1 includes a sample tray and fans. The sample tray holds a covered digestion tube. Two cooling fans are located on the right side of the sample tray to cool the digestion tube after digestion. The sample tray has a double-layer structure with two concentric circular holes in its sample port, making the digestion tube more stable inside the sample tray. It is made of acid- and heat-resistant polytetrafluoroethylene (PTFE). The digestion tube is flat-bottomed, cylindrical, with a threaded, protruding cylindrical opening that screws onto a matching cap. It is made of borosilicate glass.

[0029] The multi-axis collaborative module 2 is located on top of the instrument. Depending on the actual application, it can be configured with a Cartesian coordinate system for the x, y, and z axes, or a polar coordinate system. With the help of a computer control system, the axes cooperate and operate in an orderly manner, enabling the rotary electric servo gripper to move freely in three-dimensional space.

[0030] The rotary electric servo gripper can grasp the covered digestion tube, and can also tighten or loosen the digestion tube cap by clamping and rotating.

[0031] The liquid addition module 3 includes 8 reagent pumps. The inlet and outlet of the reagent pumps are connected by capillary tubes. The inlet tube is inserted into the corresponding reagent bottle filled with reagent, and the outlet tube is fixed to the liquid addition arm.

[0032] The reagent bottles contain eight reagents, namely high-concentration ferrous ammonium sulfate, low-concentration ferrous ammonium sulfate, indicator, pure water 1, high-concentration potassium dichromate, low-concentration potassium dichromate, pure water 2, and silver sulfate-sulfuric acid. Depending on the type of test sample, the reagent pump adds reagents to the digestion tube through the reagent tubing. The concentration range of the high-concentration potassium dichromate solution is 0.1 mol / L-0.5 mol / L, and the added volume ranges from 1 ml to 3 ml; the concentration of the low-concentration potassium dichromate solution is 0.1 mol / L-0.5 mol / L, and the added volume ranges from 1 ml to 3 ml; the added volume of pure water 1 is 1 ml to 3 ml; the added volume of pure water 2 is 40 ml to 80 ml; the added volume of the indicator is 0.5 ml to 2.0 ml; the concentration of silver sulfate-sulfuric acid is 30 g / L-80 g / L (mass-volume ratio), and the added volume is 3 ml to 8 ml; ferrous ammonium sulfate is used as a titrant, with the high-concentration ferrous ammonium sulfate concentration being 0.01 mol / L-0.05 mol / L and the low-concentration ferrous ammonium sulfate concentration being 0.001 mol / L-0.005 mol / L.

[0033] The liquid addition arm has seven small holes for fixing the pipes, so that the capillary tube openings face downwards. During liquid addition, the liquid addition arm assembly moves the liquid outlet pipe forward to the digestion pipe opening at the liquid addition position for liquid addition. After liquid addition is completed, the liquid addition arm assembly moves the pipe backward to the waste discharge tank of the waste discharge assembly.

[0034] The waste discharge component is responsible for discharging waste liquid, which mainly comes from the waste liquid generated by the washing pipelines of various reagents.

[0035] The digestion module 4 is located directly in front of the sample tray. The heating plate provides a heat source for the graphite digestion holes, and the temperature controller controls the temperature to perform mercury-free, high-silver sealed digestion of the sample in the covered digestion tube.

[0036] The color sensor in detection module 5 monitors the color change of the liquid in the digestion tube through the square hole in the detection position.

[0037] The detection position and the liquid addition position are the same device.

[0038] The motor 61 of the magnetic particle delivery module 6 drives the magnetic particle wheel groove 63 to rotate, causing the magnetic particle to fall into the digestion tube through the guide block 64.

[0039] The stirring assembly is located directly below the detection position, driving the magnetic stirrer to stir the sample.

[0040] The computer control and data processing module 8 controls the coordinated operation of all modules to complete the entire testing process.

[0041] The working process of the above-mentioned device is as follows: Taking a high-chlorine (chloride ion concentration greater than 3000 mg / L) water sample as an example, the concentrations of the reagents used are as follows: high-concentration potassium dichromate solution concentration is 0.25 mol / L; low-concentration potassium dichromate solution concentration is 0.025 mol / L; silver sulfate-sulfuric acid concentration is 60 g / L; high-concentration ferrous ammonium sulfate concentration is 0.05 mol / L; low-concentration ferrous ammonium sulfate concentration is 0.005 mol / L.

[0042] Place 12 uncapped digestion tubes on the sample tray, labeled S1-S12. Add 4 ml of pure water to S1 and S2, which are blank samples. Add 4 ml of high-chlorine standard solution with a chemical oxygen demand concentration of 100 mg / L and a chloride ion content of 15000 mg / L to S3-S8. Add 4 ml of pure water to S9-S10, which are blank control samples. S11-S12 are actual high-chlorine industrial wastewater samples. Tighten the caps on the above 12 digestion tubes.

[0043] The rotary electric servo gripper of the multi-axis collaborative module 2 moves above the covered digestion tube S1, grabs the covered digestion tube S1, and transfers it to the liquid filling position.

[0044] The rotary electric servo gripper unscrews the cap on the S1 digestion tube and moves it to the left, making room for the liquid addition arm.

[0045] According to the set program, the liquid addition module 3 adds 4ml of potassium dichromate reagent, 1ml of pure water 1 and 6ml of silver sulfate-sulfuric acid to the S1 digestion tube. Then, the multi-axis collaborative module 2 drives the rotary electric servo gripper to move back to the liquid addition position and tighten the screw cap. Then, it picks up the S1 digestion tube with the cap and transfers it to the graphite digestion hole of the digestion module 4 for heating and digestion.

[0046] Meanwhile, according to the computer control system, the digestion module 4 is preheated to 175°C, and the timing begins after the covered digestion tube is transferred to the graphite digestion hole.

[0047] Furthermore, the remaining samples were subjected to the same liquid addition and digestion steps in sequence.

[0048] The digestion process is completed after heating for 20 minutes. At this point, the rotary servo-driven electric gripper picks up the covered digestion tube and transfers it into the sample tray, and the fan immediately starts to cool it down.

[0049] After cooling, the S1 covered digestion tube is transferred to the detection position. The rotary servo electric gripper unscrews the cover of the covered digestion tube and moves it to the left side, and puts the cover into the storage slot below.

[0050] Furthermore, the magnetic particle delivery module 5 delivers magnetic particles into the cooled S1 digestion tube.

[0051] Add 65ml of pure water and 2.0ml of indicator to the S1 digestion tube using the liquid addition module 3.

[0052] Furthermore, the stirring assembly is activated, causing the magnetic rotor to rotate and thus mixing the solution evenly.

[0053] Meanwhile, the liquid addition module 3 continues to add ferrous ammonium sulfate dropwise into the S1 digestion tube.

[0054] Meanwhile, the color sensor in detection module 5 monitors the uniformly stirred solution in real time and completes the titration detection based on the color change of the solution.

[0055] After the test is completed, the multi-axis collaborative module 2 puts the digestion tube back into the sample tray, and subsequent samples are tested in sequence according to this procedure. The computer control and data processing module 8 acquires detection data in real time, calculates the titration of S3-S12, and compares the detection results of high-chlorine water samples with known concentrations, ensuring instrument performance through triple verification.

[0056] As an optional implementation, this embodiment also provides a method for determining the chemical oxygen demand (COD) of high-chlorine water samples using the aforementioned fully automated COD analyzer based on mercury-free high-silver digestion, comprising: Place a capped digestion tube on the sample tray module; The multi-axis collaborative module grabs the covered digestion tube to the liquid filling position, and the rotary electro-servo electric gripper loosens or tightens the digestion tube cap. The reagents are added sequentially to the digestion tube by the liquid addition module according to the set program. After tightening the tube cap, the tube is transferred to the digestion module for heating and digestion. After digestion, cool the sample and move it to the detection position to open the lid; A magnetic particle is introduced into the digestion tube by the magnetic particle dispensing module, pure water and indicator are added by the liquid addition module, and the stirring component is started to mix. Ferrous ammonium sulfate is added dropwise by the liquid addition module, and the color sensor of the detection module monitors the color change of the solution in real time and completes the titration. The computer control and data processing module is used to collect detection data and calculate the chemical oxygen demand (COD) results.

[0057] The accuracy of this embodiment is verified as follows: The test results for high-chlorine standard solutions S3-S6 were 100.6 mg / L, 99.6 mg / L, 99.8 mg / L, 100.0 mg / L, 100.2 mg / L, and 99.8 mg / L, respectively, with relative errors of 0.6%, -0.4%, -0.2%, 0.0%, 0.2%, and -0.2%, all within the allowable error range. This demonstrates that the deviation between the detected values ​​and the true values ​​is controllable.

[0058] The precision verification of this embodiment is as follows: The precision RSD of the high-chlorine standard solution in multiple tests was approximately 0.33%, with small data fluctuations, demonstrating the consistency of repeated testing.

[0059] The blank and practical application verification of this embodiment are as follows: The blank control water samples S9 and S10 showed detection results of 0.6 mg / L and 0.4 mg / L, respectively, close to 0 mg / L, thus eliminating background interference. The actual high-chlorine industrial wastewater showed a chemical oxygen demand (COD) of 85 mg / L, indicating that the instrument can effectively detect the COD of actual water samples.

[0060] Through the above verification, the instrument can accurately and stably detect the chemical oxygen demand (COD) of high-chlorine water samples, solving the problem of COD detection in high-chlorine environments and providing a reliable means for water quality monitoring.

[0061] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0062] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A fully automated chemical oxygen demand analyzer based on mercury-free high-silver digestion, characterized in that, include: The system includes a sample tray module, a multi-axis collaborative module, a liquid addition module, a digestion module, a detection module, a magnetic particle delivery module, and a computer control and data processing module. The sample tray module is used to place the capped digestion tube; the multi-axis collaborative module is used to grasp the capped digestion tube and transfer it between the sample tray module, the liquid addition module, and the digestion module; the liquid addition module is used to add reagents into the capped digestion tube; the digestion module is used to heat the capped digestion tube to complete mercury-free, high-silver, sealed digestion; the detection module, in collaboration with the magnetic dosing module and the liquid addition module, performs titration detection on the sample in the capped digestion tube; the computer control and data processing module is connected to the sample tray module, the multi-axis collaborative module, the liquid addition module, the digestion module, the detection module, and the magnetic dosing module, respectively, and collaboratively controls the entire sample detection process.

2. The fully automated chemical oxygen demand analyzer based on mercury-free high-silver digestion according to claim 1, characterized in that, The sample tray module includes a sample tray and a fan located on the right side of the sample tray. The fan is used to cool the digestion tube after digestion. The sample tray has a double-layer structure, and the sample hole of the sample tray has two concentric circular holes to enhance the stability of the digestion tube placement.

3. The fully automated chemical oxygen demand analyzer based on mercury-free high-silver digestion according to claim 1, characterized in that, The multi-axis collaborative module includes an x-axis movement module, a y-axis movement module, and a z-axis movement module; the x-axis movement module and the z-axis movement module include a motor, a slider, and a slide rail; the y-axis movement module includes a lead screw motor, a slider, and a rotary electro-servo electric gripper; the z-axis movement module is fixed on the slider of the x-axis movement module, and the y-axis movement module is fixed on the slider of the z-axis movement module, so that the rotary electro-servo electric gripper can achieve three-dimensional movement under computer control.

4. The fully automated chemical oxygen demand analyzer based on mercury-free high-silver digestion according to claim 3, characterized in that, The multi-axis collaborative module adopts a polar coordinate motion system to realize the three-dimensional spatial motion of the rotary electric servo gripper.

5. The fully automated chemical oxygen demand analyzer based on mercury-free high-silver digestion according to claim 3, characterized in that, The rotary electric servo gripper is used to grasp the digestion tube with a cap, and tightens or loosens the cap of the digestion tube by clamping and rotating.

6. The fully automated chemical oxygen demand analyzer based on mercury-free high-silver digestion according to claim 1, characterized in that, The liquid addition module includes several reagent pumps, a liquid addition arm assembly, a liquid addition point, and a waste discharge assembly. The liquid addition arm assembly has a reagent channel, and the reagent tubing of the reagent pump is fixed to the reagent channel of the liquid addition arm assembly. The liquid addition point is fixed directly in front of the liquid addition arm assembly, and the liquid addition arm assembly drives the liquid outlet to align with the digestion tube on the liquid addition point. The waste discharge assembly is located directly below the liquid addition arm assembly for reagent waste discharge.

7. The fully automated chemical oxygen demand analyzer based on mercury-free high-silver digestion according to claim 6, characterized in that, The liquid filling position includes a liquid filling tank and an electric gripper. The liquid filling tank has openings on both sides, and the electric gripper passes through the openings to clamp or release the digestion tube.

8. The fully automated chemical oxygen demand analyzer based on mercury-free high-silver digestion according to claim 6, characterized in that, The waste discharge assembly includes a waste discharge tank and a waste discharge peristaltic pump, which are connected via an acid-resistant rubber hose; the waste discharge pump is connected to a silver halide waste liquid recovery device.

9. The fully automated chemical oxygen demand analyzer based on mercury-free high-silver digestion according to claim 1, characterized in that, The digestion module includes several graphite digestion holes, a heating plate, and a temperature controller; the heating plate is located below the graphite digestion holes and provides a heat source, and the temperature controller is used for temperature control; depending on the type of test sample, the heating temperature range is 50℃ to 300℃, and the heating time range is 10 min to 120 min.

10. A method for determining the chemical oxygen demand (COD) of a high-chlorine water sample using a fully automated COD analyzer based on mercury-free high-silver digestion as described in any one of claims 1 to 9, comprising: Place a capped digestion tube on the sample tray module; The multi-axis collaborative module grabs the covered digestion tube to the liquid filling position, and the rotary electro-servo electric gripper loosens or tightens the digestion tube cap. The reagents are added sequentially to the digestion tube by the liquid addition module according to the set program. After tightening the tube cap, the tube is transferred to the digestion module for heating and digestion. After digestion, cool the sample and move it to the detection position to open the lid; A magnetic particle is introduced into the digestion tube by the magnetic particle dispensing module, pure water and indicator are added by the liquid addition module, and the stirring component is started to mix. Ferrous ammonium sulfate is added dropwise by the liquid addition module, and the color sensor of the detection module monitors the color change of the solution in real time and completes the titration. The computer control and data processing module is used to collect detection data and calculate the chemical oxygen demand (COD) results.

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