Permanganate index on-line automatic measuring method and system

Abstract

The application provides a permanganate index online automatic determination method and system, the method comprises the following steps: synchronously acquiring the oxidation-reduction potential signal, the absorbance signal and the temperature signal of the solution to be measured at the same measurement point, and performing temperature drift compensation on the oxidation-reduction potential to extract the potential change characteristics, so as to determine the predicted titration volume interval. If the potential change characteristics meet the first end point determination condition and the absorbance signal reaches the verification threshold, the corresponding volume is determined as the first end point; if the potential change characteristics do not meet the condition or the absorbance signal does not reach the verification threshold, the absorbance change characteristics are extracted based on the absorbance signal, and the second end point is determined when the second end point determination condition is met. According to the obtained number of end points and the difference between the two end points, the final titration end point is determined, and the permanganate index is calculated. The application improves the end point recognition accuracy and the anti-interference ability through the cooperative decision of the potential and the absorbance signals, and is suitable for online automatic monitoring of complex water bodies.

Description

Technical Field

[0001] This invention relates to the technical field of automatic water quality analysis, and in particular to an online automatic method and system for determining the permanganate index. Background Technology

[0002] The permanganate index is an important comprehensive indicator characterizing the total amount of organic matter and inorganic reducing substances in water that can be oxidized by potassium permanganate. It is widely used in water quality monitoring of surface water, drinking water sources, and wastewater treatment processes. Currently, the main methods for determining the permanganate index include manual colorimetric methods and automated titration methods based on oxidation-reduction potential (ORP).

[0003] Manual colorimetric methods (such as GB 11892-89) typically use a stable pink color at the titration endpoint as the determining factor. While the principle is intuitive, in practical applications, they heavily rely on human visual judgment and are easily affected by operator experience, lighting conditions, and subjective differences, resulting in poor repeatability and consistency. This makes them unsuitable for long-term online monitoring and automated analysis. Even with the introduction of photoelectric detectors for color recognition, issues such as deep sample background color, high turbidity, or strong scattered and stray light interference can still lead to absorbance signal distortion, thus affecting the reliability of endpoint determination.

[0004] In contrast, automated titration based on ORP signals can reduce human intervention and has the potential to achieve continuous online measurement. However, in actual water samples, especially in complex water bodies containing multiple redox components, the potential jump generated during potassium permanganate titration may be insignificant, non-unique, or even delayed or abnormal in morphology, making it difficult to stably and accurately identify the true titration endpoint by relying solely on ORP signals. Furthermore, both the ORP electrode output potential and the potassium permanganate oxidation reaction process are highly sensitive to temperature changes. Without effective temperature compensation and kinetic correction, measurement results can easily fluctuate with environmental conditions, affecting the consistency and reliability of endpoint determination.

[0005] Therefore, existing technologies generally suffer from limitations such as the limited applicability of single criteria, insufficient anti-interference capabilities, and low stability in endpoint identification under complex water sample conditions. To address these shortcomings, there is an urgent need for an automated measurement method that can comprehensively utilize information from solution color changes and redox potential changes. This method would reduce the risk of single-signal failure through multi-signal collaborative judgment and incorporate effective correction methods for temperature effects to improve the accuracy and robustness of endpoint determination. Simultaneously, to meet the demands of online monitoring, miniaturization, and integration, it is also necessary to optimize the sensor structure, enabling the integrated arrangement of multiple detection units at the same measurement location. This would reduce measurement errors introduced by spatial differences and improve the overall stability and practicality of the system. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides an online automatic determination method and system for permanganate index.

[0007] In a first aspect, the present invention proposes an online automatic method for determining the permanganate index, the method comprising:

[0008] S1, acquire the redox potential signal, absorbance signal and temperature signal of the solution to be tested in real time and synchronously at the same measurement point;

[0009] S2, temperature drift compensation is performed on the redox potential signal based on the temperature signal, and potential change characteristics are extracted based on the compensated redox potential signal. The predicted titration volume range is determined using the potential change characteristics.

[0010] S3, within the predicted titration volume range, in response to the potential change feature satisfying endpoint determination condition one and the absorbance signal exceeding the absorbance verification threshold, the titration volume corresponding to the potential change feature is determined as the first endpoint; in response to the potential change feature satisfying endpoint determination condition one but the absorbance signal is less than the absorbance verification threshold, or the potential change feature not satisfying endpoint determination condition one, the absorbance change feature is extracted based on the absorbance signal, and when the absorbance change feature satisfies endpoint determination condition two, the corresponding titration volume is determined as the second endpoint;

[0011] S4, in response to obtaining only the first endpoint or only the second endpoint within the predicted titration volume range, the first endpoint or the second endpoint is used as the titration endpoint; in response to obtaining the first endpoint and the second endpoint respectively within the predicted titration volume range, the titration endpoint is determined based on the difference between the first endpoint and the second endpoint.

[0012] S5, calculate the permanganate index of the test solution based on the titration endpoint.

[0013] The above technical solution enables real-time synchronous monitoring of ORP, absorbance, and temperature at the same sampling point, avoiding signal timing deviations caused by spatial misalignment; through dual-signal coordination and dynamic interval prediction mechanisms, it improves the accuracy and robustness of endpoint determination, and significantly enhances the adaptability and stability of online measurement.

[0014] Furthermore, the compensation relationship for temperature drift compensation is as follows:

[0015]

[0016] In the formula, This is the temperature-corrected redox potential value. The potential reference value is at the reference temperature. This is the temperature compensation coefficient, with a value ranging from 1.0 to 3.0 mV / ℃. This refers to the solution temperature collected in real time during the titration process. The reference temperature is used. By implementing temperature drift compensation on the redox potential signal, the electrode response remains consistent under different ambient temperatures, improving the comparability and reliability of the potential signal.

[0017] Furthermore, step S2 also includes correcting the titration reaction rate based on the Arrhenius temperature correction factor to adjust the predicted titration volume range, wherein the Arrhenius temperature correction factor satisfies:

[0018]

[0019] In the formula, This is the temperature correction factor. The apparent activation energy of the reaction. The base of the natural logarithm, This is the universal gas constant. This refers to the solution temperature collected in real time during the titration process. The reference temperature is used. Arrhenius temperature compensation is employed to correct the titration reaction rate, ensuring that the endpoint determination maintains a consistent degree of reaction under different temperature conditions, thus improving the consistency of reaction kinetics and the repeatability of the determination.

[0020] Furthermore, the predicted titration volume interval is determined based on the predicted rate of change threshold, which corresponds to the titration volume position. The predicted titration volume interval is then determined based on the volume position. The predicted rate of change threshold is dynamically set based on the real-time titration curve, or it can be the first derivative of the redox potential signal after compensation during the initial titration stage as a function of the titration volume. The weighted combination of the mean and its standard deviation is used. By dynamically predicting the volume range where the endpoint may occur, the invalid search range is reduced, the endpoint detection efficiency is improved, and noise interference is reduced.

[0021] Furthermore, the determination of the first endpoint includes: calculating the first derivative of the compensated redox potential signal as a function of titration volume. Within the predicted titration volume range, when the first derivative is detected... If a peak point 1 that meets the endpoint determination condition 1 appears, and the absorbance signal corresponding to peak point 1 exceeds the absorbance verification threshold, the titration volume corresponding to peak point 1 is determined as the first endpoint. By extracting the ORP derivative peak and combining it with absorbance verification, the determination of the first endpoint is ensured to meet both electrochemical and colorimetric criteria, significantly reducing the probability of misjudgment.

[0022] Furthermore, the determination of the second endpoint includes: calculating the first derivative of the compensated redox potential signal as a function of titration volume. In response to the detection of the first derivative within the predicted titration volume range A peak point 1 that meets endpoint determination condition 1 appears, but the absorbance signal corresponding to peak point 1 does not exceed the absorbance verification threshold; or no first derivative is detected within the predicted titration volume range. If a peak point that satisfies endpoint criterion 1 is found, calculate the first derivative of the absorbance signal as a function of titration volume. In response to the detection of the first derivative within the predicted titration volume range If a second peak point is found that satisfies endpoint determination condition two, the titration volume corresponding to peak point two is determined as the second endpoint. In the event of an abnormal or unavailable redox potential signal, the system can automatically revert to the absorbance derivative endpoint determination, achieving redundancy in the titration process and improving the endpoint detectability of the system under complex water quality conditions.

[0023] Furthermore, endpoint determination also includes the following: calculating the first derivative of the compensated redox potential signal as a function of titration volume. When the first derivative is detected within the predicted titration volume range A peak point 1 appears that satisfies endpoint criterion 1, but the absorbance signal corresponding to peak point 1 does not exceed the absorbance verification threshold. Calculate the first derivative of the absorbance signal as a function of titration volume. In response to the detection of the first derivative within the predicted titration volume range If peak point two, which satisfies endpoint determination condition two, does not appear, the titration volume corresponding to peak point one is designated as a suspected endpoint. In boundary situations where multiple signals are not entirely reliable, a traceable endpoint output mechanism is provided to ensure uninterrupted measurement and support subsequent quality control.

[0024] Furthermore, the first condition for determining the endpoint is met:

[0025]

[0026] In the formula, The ORP derivative value corresponding to peak point one. The first threshold, The ORP derivative value is the value corresponding to the sampling point preceding the peak point. This represents the ORP derivative value corresponding to the next sampling point after the peak point. By constraining the local maximum characteristics of the ORP derivative, noise disturbances are eliminated, ensuring the authenticity of the endpoint jump.

[0027] Furthermore, the first derivative values ​​of at least two sampling points before and after peak point one are higher than the preset proportion of peak point one, and the appearance of peak point one is later than the time when the absorbance signal begins to rise. The reliability of the ORP peak is further confirmed by peak width and colorimetric timing verification, effectively avoiding false endpoints caused by spurious jumps.

[0028] Furthermore, the second condition for determining the endpoint is defined as simultaneously satisfying the following relationships:

[0029]

[0030] In the formula, This represents the absorbance derivative value corresponding to peak point two. The second threshold, This represents the absorbance derivative value corresponding to the sampling point preceding the peak point two. This represents the absorbance derivative value corresponding to the next sampling point after the peak point. The endpoint of colorimetric analysis is identified by the maximum value of the absorbance derivative, improving endpoint identification capability when ORP is unavailable.

[0031] Furthermore, the search interval for peak point two is defined as the point where the absorbance signal first significantly deviates from the baseline noise until the absorbance change rate falls back to the baseline at the beginning of the titration. The point where the absorbance signal first significantly deviates from the baseline noise satisfies... In the formula, This represents the baseline mean absorbance at the initial stage of titration. The standard deviation of the absorbance signal during the baseline phase. The preset parameter has a value range of 2 to 5, with a preferred value of 3. By limiting the colorimetric peak search range, noise interference in the colorless stage at the beginning of titration is avoided, thus improving the reliability of absorbance derivative peak identification.

[0032] Secondly, the present invention proposes an online automatic determination system for permanganate index, including a signal acquisition module configured to acquire, in real time, synchronously collect the redox potential signal, absorbance signal and temperature signal of the solution to be tested;

[0033] The potential change feature calculation module is configured to perform temperature drift compensation on the redox potential signal based on the temperature signal, extract potential change features based on the compensated redox potential signal, and use the potential change features to determine the predicted titration volume range.

[0034] The endpoint determination module is configured to, within the predicted titration volume range, determine the titration volume corresponding to the potential change feature as the first endpoint when the potential change feature meets endpoint determination condition one and the absorbance signal exceeds the absorbance verification threshold; and when the potential change feature meets endpoint determination condition one but the absorbance signal is less than the absorbance verification threshold, or the potential change feature does not meet endpoint determination condition one, extract the absorbance change feature based on the absorbance signal, and determine the corresponding titration volume as the second endpoint when the absorbance change feature meets endpoint determination condition two.

[0035] The endpoint decision module is configured to, in response to obtaining only the first endpoint or only the second endpoint within the predicted titration volume range, use the first endpoint or the second endpoint as the titration endpoint; and in response to obtaining the first endpoint and the second endpoint respectively within the predicted titration volume range, determine the titration endpoint based on the difference between the first endpoint and the second endpoint.

[0036] The permanganate index calculation module is configured to calculate the permanganate index of the test solution based on the titration endpoint.

[0037] Furthermore, the signal acquisition module includes a hollow rod-shaped probe housing and an optical detection unit, a redox potential measurement unit, and a temperature sensing unit integrated within the probe housing; the end of the probe housing is provided with a measurement window area that communicates with the external solution to be tested, wherein the measurement positions corresponding to the optical detection unit, the redox potential measurement unit, and the temperature sensing unit are all located within the probe housing end area corresponding to the measurement window area.

[0038] In the above technical solution, by integrating redox potential measurement, absorbance detection and temperature sensing into the same probe housing, and placing the measurement points of each sensing unit in the same measurement window area, the synchronous acquisition of multiple signals at the same measurement location is realized. This fundamentally avoids measurement deviations caused by spatial separation or time asynchrony of sensors, and improves the consistency and reliability of the data.

[0039] Thirdly, this invention proposes an online automatic permanganate index determination device, comprising a probe housing and an optical detection unit, a redox potential measurement unit, a temperature sensing unit, and a circuit connection unit integrated within the probe housing, wherein:

[0040] The probe housing is used to form an installation cavity and contact the solution to be tested. The end of the probe housing is provided with a measurement window area that communicates with the external solution to be tested. The measurement points of the optical detection unit, the redox potential measurement unit, and the temperature sensing unit are located within the measurement window area to achieve synchronous detection of the same measurement position.

[0041] An optical detection unit is used to emit detection light outward and receive the backlight signal scattered or reflected by the solution to be tested. The optical detection unit includes a light source, a photoelectric receiving component, and an optical transmission window for forming an optical path with the external solution to be tested.

[0042] The redox potential measurement unit includes a measuring electrode disposed at the end of the probe housing and a reference electrode that is connected to an external solution through an ion pathway;

[0043] The temperature sensing unit is located near the optical detection unit and the redox potential measurement unit;

[0044] The circuit connection unit includes a circuit carrier disposed within the probe housing, and circuit traces formed on the circuit carrier for providing power and signal transmission to the optical detection unit, the redox potential measurement unit, and the temperature sensing unit.

[0045] In the above technical solution, by integrating the optical detection unit, redox potential measurement unit, temperature sensing unit, and circuit connection unit into the same probe housing, and ensuring that each measurement point is located in the measurement window area, synchronous optical, electrochemical, and temperature detection of the same solution volume is achieved, significantly reducing measurement errors caused by spatial deviation. At the same time, the integrated design of the circuit unit improves the probe's structural compactness, anti-interference ability, and long-term stability, thereby significantly improving the accuracy, real-time performance, and applicability of the online measurement system.

[0046] Furthermore, the probe housing is made of stainless steel and has an overall slender, hollow, cylindrical structure with a measurement window area at the end. The slender stainless steel cylindrical housing provides excellent mechanical strength, corrosion resistance, and electromagnetic shielding capabilities, allowing for flexible installation in flow cells and narrow reaction chambers. The measurement window at the end ensures that all detection units operate in the same liquid environment, contributing to the consistency and stability of the test results. Its outer diameter is preferably controlled within the range of 12mm to 20mm to facilitate probe insertion into online measurement environments such as standard reaction cells or flow cells.

[0047] Furthermore, the optical transmission windows include two optical transmission windows respectively disposed on the outside of the light source and the photoelectric receiving component, and the optical transmission windows are made of sapphire glass. The use of two sapphire optical transmission windows in conjunction with the light source and the photoelectric receiving component respectively can maintain good light transmittance and wear resistance in highly corrosive, high-pressure, or long-term immersion environments, thereby ensuring optical path stability and improving the sensitivity and reliability of colorimetric measurements.

[0048] Furthermore, the optical transmission windows include a first optical transmission window and a second optical transmission window spaced apart along the axial direction of the probe housing. The first optical transmission window corresponds to the light source, and the second optical transmission window corresponds to the photoelectric receiving component. The light source is an LED patch. By using the two optical transmission windows spaced apart along the axial direction, a stable incident light path and a receiving light path are formed, improving the stability and anti-interference capability of the optical detection signal.

[0049] Furthermore, the measuring electrode is a platinum measuring electrode located at the end of the probe housing; the reference electrode is an Ag / AgCl reference electrode, which forms an ion conduction path with the external solution through a porous ceramic membrane and polyacrylamide gel. The platinum measuring electrode provides excellent electrochemical inertness and stability; the Ag / AgCl reference electrode forms a stable ion pathway through the porous ceramic membrane and gel, making the reference interface potential more reliable and improving the response speed, anti-interference ability, and long-term stability of ORP measurement.

[0050] Furthermore, the circuit carrier is a flexible circuit board, which forms power and signal traces for the optical detection unit, redox potential measurement unit, and temperature sensing unit by etching copper foil. The flexible circuit board, through copper foil etching to form power and signal traces, enables high-density wiring of multiple sensors in a confined space; its flexible attachment structure reduces the impact of internal stress and vibration, thereby improving the reliability and electromagnetic interference resistance of the probe.

[0051] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0052] 1. This invention achieves dual-channel mutual verification for endpoint determination by simultaneously acquiring oxidation-reduction potential, absorbance, and temperature signals at the same measurement location and performing collaborative analysis of multi-source signals. This effectively reduces the risk of misjudgment caused by single signal drift, noise interference, or sensor malfunction, making the measurement method applicable to application scenarios with complex water composition and many interfering factors.

[0053] 2. This invention compensates for temperature drift in the redox potential signal and performs dynamic analysis of the titration process by combining potential change characteristics. It can predetermine a reasonable predicted titration volume range before the titration endpoint occurs, thereby limiting the endpoint search range to the critical reaction stage. This not only improves the accuracy and stability of endpoint identification, but also effectively reduces invalid data processing and improves the response speed and operating efficiency of online measurement.

[0054] 3. When the potential signal does not meet the endpoint determination conditions or there is uncertainty in the potential response, the present invention automatically triggers a colorimetric backoff mechanism based on the absorbance change characteristics, and comprehensively judges different endpoint results through the endpoint decision strategy. This enables the system to output a titration endpoint with clear criteria even in cases of complex water samples, significant differences in reaction kinetics, or abnormal sensor conditions, thus significantly enhancing the robustness and reliability of the system.

[0055] 4. This invention integrates the optical detection unit, the oxidation-reduction potential measurement unit, and the temperature sensing unit into the same probe housing, achieving a compact structure and high measurement synchronization of the online detection device design. This reduces the complexity of installation and maintenance, minimizes measurement errors caused by the dispersed arrangement of sensors, and is suitable for long-term continuous online monitoring and miniaturized, integrated water quality analysis equipment. Attached Figure Description

[0056] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of the invention. Many anticipated advantages of the embodiments and other embodiments of the invention will be readily recognized as they become better understood through reference to the following detailed description. Elements in the drawings are not necessarily to scale. The same reference numerals refer to corresponding similar parts.

[0057] Figure 1 This is a flowchart of an online automatic determination method for permanganate index according to an embodiment of the present invention;

[0058] Figure 2 This is a framework diagram of an online automatic permanganate index determination system according to an embodiment of the present invention;

[0059] Figure 3 This is a schematic diagram of an online automatic permanganate index measuring device according to an embodiment of the present invention;

[0060] Figure 4 This is a schematic diagram of the structure of a computer system used to implement the electronic device of the present application.

[0061] The meanings of the numbers in the diagram are as follows: 100-Probe housing, 200-Optical detection unit, 300-Oxidation-reduction potential measurement unit, 400-Temperature sensing unit, 500-Circuit connection unit, 600-Measurement optical path, 800-Online automatic permanganate index determination system, 110-Measurement window area, 210-Light source, 220-Photoelectric receiving component, 230-Optical transmission window, 310-Measurement electrode, 320-Reference electrode, 330-Porous ceramic diaphragm, 340-Polyacrylamide gel, 311-ORP electrode lead, 510-Circuit carrier, 520-Circuit lead, 401-CPU, 402-ROM, 403- RAM, 404-Bus, 405-I / O Interface, 406-Input Section, 407-Output Section, 408-Storage Section, 409-Communication Section, 410-Driver, 411-Removable Media, 801-Signal Acquisition Module, 802-Potential Change Characteristic Calculation Module, 803-Endpoint Determination Module, 804-Endpoint Decision Module, 805-Permanganate Index Calculation Module. Detailed Implementation

[0062] In the following detailed description, reference is made to the accompanying drawings, which form part of the detailed description and are illustrated by specific illustrative embodiments in which the invention may be practiced. In this regard, directional terms such as “top,” “bottom,” “left,” “right,” “up,” “down,” etc., are used with reference to the orientation of the described figures. Because components of the embodiments can be positioned in several different orientations, directional terms are used for illustrative purposes and are by no means limiting. It should be understood that other embodiments may be utilized or logical changes may be made without departing from the scope of the invention. Therefore, the following detailed description should not be taken in a limiting sense, and the scope of the invention is defined by the appended claims.

[0063] This invention proposes an online automated method for determining the permanganate index. For example... Figure 1 As shown, the method includes:

[0064] S1, acquire the redox potential signal, absorbance signal and temperature signal of the solution to be tested in real time and synchronously at the same measurement point;

[0065] In some specific embodiments, the same measurement point is located in the measurement window area at the lower end of the probe housing. Since the outer diameter of the probe housing is preferably controlled between 12mm and 20mm, the detection ends of the optical detection unit, the redox potential measurement unit, and the temperature sensing unit can be understood as being in a local area with a high spatial position. This allows for real-time synchronous acquisition of potential, optical, and temperature signals of the solution to be tested within the same measurement window area, thus avoiding measurement delays or deviations caused by differences in spatial distribution.

[0066] S2, temperature drift compensation is performed on the redox potential signal based on the temperature signal, and potential change characteristics are extracted based on the compensated redox potential signal. The predicted titration volume range is determined using the potential change characteristics.

[0067] In some specific embodiments, potential-temperature compensation of the redox potential signal is based on the temperature-potential variation law obtained after multiple experimental measurements of the redox potential output characteristics under different temperature conditions, and an empirical temperature compensation coefficient is statistically derived from this. The temperature compensation employs a linear correction relationship, and its compensation formula is as follows:

[0068]

[0069] In the formula, This is the temperature-corrected redox potential value. This serves as a reference value for the potential at a reference temperature (e.g., 25°C). This is the temperature compensation coefficient, with a value ranging from 1.0 to 3.0 mV / ℃. This refers to the temperature of the solution being tested, collected in real time during the titration process. The reference temperature is used. Through the above temperature drift compensation, the influence of temperature changes on the redox potential signal can be effectively reduced, improving the stability and comparability of potential measurements.

[0070] In some specific embodiments, step S2 further includes kinetic temperature compensation of the titration reaction rate based on the Arrhenius temperature correction factor to adjust the predicted titration volume range. Kinetic compensation is performed by calculating the temperature correction factor. To achieve this, the correction factor is based on real-time temperature. Compared with reference temperature The Arrhenius relation for the rate constant of the titration reaction was determined. Specifically, the rate constant at the real-time temperature can be expressed as: The reaction rate constant at the reference temperature can be expressed as: The temperature correction factor can be obtained. ,in, Pre-exponential factor, The apparent activation energy of the reaction can be determined in the laboratory by measuring the rate constant of the reaction between potassium permanganate and typical organic compounds at different temperatures. And on right The slope is obtained by plotting the graph. However, by reverse calculation, The universal gas constant is 8.314 J / (mol·K). This is the Kelvin temperature; for easier calculation in Celsius, it is rewritten as... In the formula, This is the temperature correction factor. The apparent activation energy of the reaction. The base of the natural logarithm, This is the universal gas constant. This refers to the solution temperature collected in real time during the titration process. This is a reference temperature. The numerical value is used to characterize the trend of the reaction rate at the current temperature relative to the reference temperature. This indicates that the reaction rate is faster at the current temperature than at the reference temperature, which allows for earlier entry into the predicted titration volume range, thus shortening the determination time. This indicates that the reaction rate at the current temperature is slower than that at the reference temperature, and the reaction should be allowed to proceed more fully by appropriately delaying the entry into the predicted titration volume range. This indicates that the current temperature equals the reference temperature, and the titration process maintains the standard reaction rate. Through this kinetic temperature compensation, it can be ensured that the titration reaction reaches the same degree of reaction under different temperature conditions, giving the predicted titration volume range better temperature adaptability, thereby improving the accuracy and consistency of endpoint determination.

[0071] Furthermore, based on temperature correction factors Temperature correction is applied to the titration volume, and the corrected titration volume is... Determined according to the following relationship: ,in, This represents the raw titration volume acquired in real time. During the titration process, the curves showing the changes in redox potential and absorbance signals with the titration volume are based on the corrected titration volume. The system was constructed and analyzed to eliminate the influence of temperature changes on the titration reaction rate and signal change rate, thereby ensuring that the preset thresholds for determining the first derivative of redox potential and the first derivative of absorbance remain consistent and comparable under different temperature conditions.

[0072] In some specific embodiments, the calculation steps for predicting the titration volume range include: firstly, calculating the first derivative of the temperature-compensated redox potential signal as a function of the titration volume. During the titration process, several latest sampling points were continuously acquired. Data (e.g., 10 data points) are fitted with linear regression to obtain... ,in, for , The titration volume. The slope of the regression line. Used to characterize the trend of the rate of change of ORP, when the slope When the value is significantly positive and shows a continuous increasing trend, it indicates that the titration reaction has entered the rapid rise phase of ORP. A predicted rate of change threshold is dynamically set based on the real-time titration curve, and the predicted volume point at which the predicted rate of change threshold will be reached is calculated, i.e., the predicted titration volume range. Specifically, the predicted rate of change threshold can also be preferably an estimated value. The peak value is 20% to 40%, or the average value of the derivative at the beginning of titration plus 5 to 10 times the standard deviation. Alternatively, it can be set to 25% to 35% of the typical peak height in historical titration data.

[0073] S3, within the predicted titration volume range, in response to the potential change feature satisfying endpoint determination condition one and the absorbance signal exceeding the absorbance verification threshold, the titration volume corresponding to the potential change feature is determined as the first endpoint; in response to the potential change feature satisfying endpoint determination condition one but the absorbance signal being less than the absorbance verification threshold, or the potential change feature not satisfying endpoint determination condition one, the absorbance change feature is extracted based on the absorbance signal, and when the absorbance change feature satisfies endpoint determination condition two, the corresponding titration volume is determined as the second endpoint.

[0074] After entering the predicted titration volume range of high-precision monitoring, continuous monitoring is performed. The change in , and search within the predicted titration volume range for the derivative abrupt peak point that satisfies endpoint criterion one. When a certain sampling point Simultaneously satisfy: And sampling points If the absorbance signal meets the absorbance verification threshold, then the sampling point... The first peak point of the ORP derivative is identified as satisfying the local maximum characteristic. In the formula, The ORP derivative value corresponding to peak point one. The first threshold; The ORP derivative value is the value corresponding to the sampling point preceding the peak point. This is the ORP derivative value corresponding to the next sampling point after the peak point.

[0075] Preferably, the first threshold is used to exclude minor fluctuations caused by noise, and is preferably set to 10% to 20% of the normal peak height based on historical experimental data. The baseline noise range is 5 to 10 times, with the larger value being taken. Preferably, to further ensure that the peak point is a genuine abrupt change rather than an instantaneous pulse, the peak width is also judged, requiring the peak point... At least several (e.g., 2-3) sampling points on both sides All remained at peak levels A certain proportion (e.g., 0.5 times) or higher, meaning that the first derivative values ​​of at least two sampling points before and after peak point one are higher than the preset proportion threshold of peak point one. More preferably, the timing of the ORP jump and the colorimetric signal is correlated and verified, requiring that the occurrence time of peak point one is no earlier than the time when the absorbance signal begins to rise, to exclude false jumps caused by other oxidizing or reducing substances. When the above jump conditions are met and the absorbance signal corresponding to peak point one exceeds the preset absorbance verification threshold, the titration volume corresponding to peak point one is determined as the first endpoint.

[0076] In some specific embodiments, the step of determining the second endpoint includes: firstly calculating the first derivative of the compensated redox potential signal as a function of titration volume. If a peak point satisfying endpoint criterion 1 is detected within the predicted titration volume range, but the absorbance signal corresponding to peak point 1 does not reach the absorbance verification threshold, or if no peak point satisfying endpoint criterion 1 is detected within the predicted titration volume range, the absorbance derivative backoff criterion mechanism is activated, and the first derivative of the absorbance signal as a function of titration volume is calculated. Preferably, before determining the absorbance derivative, a baseline interval can be established using the initial absorbance data from the early stage of titration, i.e., the absorbance... Statistical analysis was performed on continuous samples during the undeveloped color stage to obtain the average value. and baseline standard deviation ; then The search range is limited to the first time the absorbance significantly deviates from the baseline noise range (e.g., The process continues until the rate of change in absorbance falls back to the baseline position at the beginning of the titration, thus eliminating noise interference from the colorless phase at the beginning of the titration. In the formula, This represents the baseline mean absorbance at the initial stage of titration. The standard deviation of the absorbance signal during the baseline phase. This is a preset parameter, with a value ranging from 2 to 5, preferably 3, to achieve a lower false alarm rate. Within this effective range, the absorbance derivative is searched. Local maxima. When a certain sampling point The endpoint determination condition two must be met, that is, the following conditions must be met simultaneously: In the formula, This represents the absorbance derivative value corresponding to peak point two. The second threshold is preferably set to the standard deviation of the absorbance baseline. Five to ten times the normal value, to exclude minor fluctuations during periods of stability; and These are the absorbance derivatives of the adjacent sampling points before and after peak point two, respectively, used to limit the local maximum characteristic of peak point two.

[0077] Further preferably, to avoid misjudgment caused by transient noise pulses, the peak width is also constrained, that is, the absorbance derivative values ​​of at least a number of sampling points (e.g., 2-3) on both sides of the second peak point are required to be significantly higher than the baseline noise level, and the original absorbance corresponding to the second peak point is also required to be higher. At this point, the absolute value should be within a reasonable range, neither approaching the baseline (to avoid insufficient color development) nor reaching the detector saturation value (to avoid peak distortion). When the above conditions are met, the titration volume corresponding to the second peak point is determined as the second endpoint.

[0078] S4, in response to obtaining only the first endpoint or only the second endpoint within the predicted titration volume range, the first endpoint or the second endpoint is used as the titration endpoint; in response to obtaining the first endpoint and the second endpoint respectively within the predicted titration volume range, the titration endpoint is determined based on the difference between the first endpoint and the second endpoint.

[0079] In some specific embodiments, when the first derivative of the redox potential signal... If the endpoint determination condition one is met (indicating a sudden jump in potential) and the corresponding absorbance signal exceeds the absorbance verification threshold (indicating a pink appearance), the titration volume corresponding to the jump point is determined as the first endpoint, which typically reflects the complete oxidation of easily oxidizable organic matter in the test solution.

[0080] When the first derivative of the redox potential signal Although endpoint criterion one is met, the corresponding absorbance signal does not reach the absorbance verification threshold, or no signal satisfying endpoint criterion one is detected within the predicted titration volume range. At the abrupt peak point, it is assumed that the redox potential signal may be interfered with or insufficient to reliably determine the endpoint. In this case, the first derivative of absorbance as a function of titration volume is used instead. The second endpoint is determined by the peak point 2. The peak point preferably satisfies the second threshold. And peak width constraints, at the same time The search interval is defined as the first time the absorbance significantly deviates from the baseline noise. )to The titration peak is drawn back to the baseline range at the beginning of the titration to eliminate noise interference during the colorless phase at the beginning of the titration, and the titration volume corresponding to this peak is determined as the second endpoint.

[0081] Furthermore, in some test solutions, the first endpoint and the second endpoint may occur simultaneously. For example, if the test solution contains two or more reducing substances with different reaction rates and redox potentials, this leads to an ORP jump and color change when the first type of substance is oxidized within the predicted titration volume range, corresponding to the first endpoint; while a weaker or slower color change occurs when the second type of less oxidizable substance is depleted. A second peak appears, corresponding to the second endpoint. The volume difference between the two endpoints is calculated. And compare it with the error threshold: If If the error is less than the error threshold, the two endpoints are considered to originate from the same chemical endpoint, and their average value can be used as the final titration endpoint; if... If the error exceeds the error threshold, it is considered to correspond to different oxidation processes. In this case, it is preferable to take the first endpoint (usually the first endpoint) as the final titration endpoint, and record the second endpoint as characteristic information of the "difficult-to-oxidize substance," but not participate in the calculation of the permanganate index. Preferably, the error threshold can be adjusted according to the titrant concentration and tube diameter.

[0082] The above mechanism can ensure that stable and reliable endpoint determination results can be obtained under various complex water sample conditions, and the system’s anti-interference ability and result repeatability are significantly improved by the dual signal cross-verification and backoff strategy.

[0083] S5, calculate the permanganate index of the test solution based on the titration endpoint.

[0084] Continue to refer to Figure 2 As an implementation of the above method, in a second aspect, this application provides an embodiment of a framework diagram for an online automatic permanganate index determination system, which is similar to... Figure 1 Corresponding to the illustrated method embodiment, this system can be specifically applied to various electronic devices. The online automatic permanganate index determination system 800 includes a signal acquisition module 801, a potential change characteristic calculation module 802, an endpoint determination module 803, an endpoint decision module 804, and a permanganate index calculation module 805, all interconnected.

[0085] The signal acquisition module 801 is configured to acquire, in real time, synchronously collect the redox potential signal, absorbance signal and temperature signal of the solution to be tested;

[0086] The potential change feature calculation module 802 is configured to perform temperature drift compensation on the redox potential signal based on the temperature signal, extract potential change features based on the compensated redox potential signal, and use the potential change features to determine the predicted titration volume range.

[0087] The endpoint determination module 803 is configured to, within the predicted titration volume range, determine the titration volume corresponding to the potential change feature as the first endpoint when the potential change feature meets endpoint determination condition one and the absorbance signal exceeds the absorbance verification threshold; and to, when the potential change feature meets endpoint determination condition one but the absorbance signal is less than the absorbance verification threshold, or the potential change feature does not meet endpoint determination condition one, extract the absorbance change feature based on the absorbance signal, and determine the corresponding titration volume as the second endpoint when the absorbance change feature meets endpoint determination condition two.

[0088] The endpoint decision module 804 is configured to, in response to obtaining only the first endpoint or only the second endpoint within the predicted titration volume range, use the first endpoint or the second endpoint as the titration endpoint; and in response to obtaining the first endpoint and the second endpoint respectively within the predicted titration volume range, determine the titration endpoint based on the difference between the first endpoint and the second endpoint.

[0089] The permanganate index calculation module 805 is configured to calculate the permanganate index of the test solution based on the titration endpoint.

[0090] In some specific embodiments, the signal acquisition module 801 obtains the signal through an online automatic permanganate index measuring device. (Continue to refer to...) Figure 3 , Figure 3 This is a schematic diagram of an online automatic permanganate index determination device according to an embodiment of the present invention. The device comprises a probe housing 100 and an optical detection unit 200, a redox potential measurement unit 300, a temperature sensing unit 400, and a circuit connection unit 500 integrated within the probe housing 100. The probe housing 100 forms a mounting cavity for accommodating the aforementioned functional units, and its lower end is provided with a measurement window area 110 that directly communicates with the external solution to be tested. The measurement positions corresponding to the optical detection unit 200, the redox potential measurement unit 300, and the temperature sensing unit 400 are all located within the measurement window area 110 at the end region of the probe housing 100, thereby enabling the optical detection point, redox potential detection point, and temperature detection point to simultaneously acquire measurement signals at the same spatial location.

[0091] In some specific embodiments, the probe housing 100 is made of 316L stainless steel to provide good mechanical strength and electromagnetic shielding performance, thereby significantly reducing interference from the external electromagnetic environment on the device's measurement signal. The probe housing 100 forms a slender cylindrical probe rod, with its outer diameter preferably controlled within the range of 12mm to 20mm, to facilitate insertion of the probe into online measurement environments such as standard reaction cells or flow cells. To improve overall sealing reliability, key connection parts of the probe housing 100 are laser-welded to achieve high-strength seals, enabling the probe to operate stably for extended periods under liquid phase conditions and withstand high-temperature and high-pressure sterilization when necessary without structural damage or seal failure. The lower end of the probe housing 100 is provided with a measurement window area 110 that is directly connected to the external solution to be tested. This allows the light source 210 of the optical detection unit 200, the optical transmission window 230 corresponding to the photoelectric receiving component 220, the measurement electrode 310 and reference electrode ion pathway of the redox potential measurement unit 300, and the temperature sensing unit 400 to all be in full contact with the external solution within the measurement window area 110. This enables synchronous measurement of the same water sample point, thereby improving the consistency and timing synchronization of the measurement signal.

[0092] In some specific embodiments, the optical detection unit 200 is disposed in the end region of the probe housing 100. The optical detection unit 200 includes a light source 210, a photoelectric receiving component 220, and optical transmission windows 230 respectively arranged outside the light source 210 and the photoelectric receiving component 220. The detection light emitted by the light source 210 enters the solution to be tested through the optical transmission window 230. After being scattered or reflected along the measurement optical path 600 in the solution, it returns through another optical transmission window 230. The photoelectric receiving component 220 receives and converts this returned light signal. The optical transmission window 230 is preferably made of sapphire glass to obtain high corrosion resistance, excellent wear resistance, and high compressive strength, thereby ensuring the stability and reliability of the optical path during long-term operation. Preferably, the light source 210 uses a high-brightness, highly monochromatic miniature LED, with a preferred central emission wavelength of 525 nm to match the characteristic absorption peak of permanganate ions in the pink color development state; this LED has the characteristics of small size, low power consumption, and long service life. The photoelectric receiving component 220 preferably uses a silicon photodiode with high responsivity to the 525nm wavelength band, enabling high-sensitivity and miniaturized optical signal detection. The darker the solution color, the higher the permanganate concentration, and the weaker the reflected light signal.

[0093] In some specific embodiments, the redox potential measurement unit 300 is disposed in the adjacent area of ​​the optical detection unit 200. It includes a measuring electrode 310 formed in a ring and arranged at the bottom of the probe, and a reference electrode 320 disposed inside the probe housing. The reference electrode 320 preferably employs a miniaturized Ag / AgCl structure, which is connected to the external test solution through an ion pathway formed by a porous ceramic membrane 330 and polyacrylamide gel 340, ensuring that the potential at the reference electrode interface is stable, thereby forming a reliable redox potential measurement benchmark. Both the measuring electrode 310 and the reference electrode 320 are electrically connected to an external transmitter unit via ORP electrode leads 311 to output a real-time redox potential signal. Preferably, a platinum ring surrounding the probe tip is used as the measuring electrode 310 to obtain excellent chemical inertness, corrosion resistance, and electrode response stability; the polyacrylamide gel 340 is a saturated KCl gel system used to improve the ionic conductivity and long-term operational stability of the reference electrode.

[0094] In some specific embodiments, the temperature sensing unit 400 is positioned adjacent to the optical detection unit 200 and the redox potential measurement unit 300, and it can be a miniature temperature sensor (such as a PT1000 platinum resistance thermometer). The temperature sensing unit 400 is in direct thermal contact with the reaction solution, acquiring the solution temperature in real time during the titration process for subsequent temperature compensation and reaction rate correction.

[0095] In some specific embodiments, the circuit connection unit 500 includes a circuit carrier 510 disposed inside the probe housing 100 and circuit traces and leads 520 on the circuit carrier 510. The circuit carrier 510 is preferably a flexible printed circuit board (FPCB), which uses polyimide film as a substrate and forms power and signal traces for the optical detection unit 200, the redox potential measurement unit 300, and the temperature sensing unit 400 by etching copper foil. The flexible printed circuit board can be closely attached to the inner wall or internal frame of the probe housing 100 and cooperate with a pre-set micro-groove structure within the probe housing 100 to accommodate and fix micro-cables, ensuring their stability within the probe housing 100 without vibration or displacement, thereby improving overall vibration and moisture resistance and reducing interference from the external electromagnetic environment on signal transmission. During assembly, the light source 210, the photoelectric receiving component 220, and the sensing elements of the temperature sensing unit 400 are directly mounted to the corresponding pad positions on the flexible printed circuit board, and a high-precision surface mount technology is used to accurately align each component. The solder paste is then melted and solidified via reflow soldering, ensuring the components are firmly soldered onto the flexible circuit board. Simultaneously, the precise positioning of the flexible circuit board ensures accurate alignment of the optical paths of the light source 210 and the photoelectric receiving component 220 with the optical transmission window 230 on the probe housing 100. The flexible circuit board layout not only achieves high-density electrical connections within the device but also reduces the space occupation and vibration risks associated with traditional cable arrangements, thereby further enhancing the reliability and durability of the device in long-term online measurement environments. Through this structural arrangement, the online automatic permanganate index determination device of the present invention achieves a high degree of integration of optical detection, redox potential detection, and temperature detection within the same measurement area, synchronously and stably acquiring multi-source signals related to titration endpoint determination, thereby significantly improving the accuracy, response speed, and applicable water sample range of online determination.

[0096] Example 1

[0097] In this embodiment, the situation where two types of endpoints may occur simultaneously or sequentially during titration is described. Due to the differences in the types of oxidizable substances and reaction kinetics in different water samples, the titration reaction may produce two endpoints with significantly different signal characteristics in some cases: a first endpoint based on a sudden jump in redox potential and a second endpoint based on the peak value of the absorbance derivative.

[0098] Typically, the first endpoint corresponds to the moment when the main, easily oxidized components in the water sample are completely oxidized by potassium permanganate. At this point, a significant jump in the redox potential (ORP) occurs, i.e., the first derivative of the compensated ORP with respect to the titration volume. A steep peak is formed, and the solution turns pink due to a trace excess of potassium permanganate, causing the absorbance signal to reach the absorbance verification threshold. Under these conditions, this derivative peak point is identified as the first endpoint. .

[0099] However, under complex water sample conditions, a typical ORP jump may not form during titration. This could be due to factors such as the presence of slow-reacting, recalcitrant components requiring higher potentials for oxidation, or the coexistence of Fe²⁺ in the water sample. + NO2 - Inorganic reducing agents or specific organic compounds may cause the solution color to gradually change with the addition of titrant, but the change in redox potential may be insufficient to produce a significant jump that satisfies the first endpoint criterion; or the ORP electrode may respond slowly due to contamination or poisoning, failing to accurately reflect the actual potential change. In these cases, although the absorbance signal gradually increases with the titration process, the calculated... It is possible that peak point 1, which satisfies endpoint determination condition 1, did not occur; it is also possible that... The ORP response exhibits a local peak, but the corresponding absorbance signal does not reach the absorbance verification threshold, indicating that the ORP jump may be caused by other interfering oxidation reactions and does not have true endpoint significance. In this case, the ORP response is considered a suspicious signal, and the colorimetric backoff mechanism is triggered.

[0100] Under the colorimetric backoff mechanism, based on the first derivative of the absorbance signal as a function of titration volume. Search for the colorimetric endpoint. To reduce the noise impact of the initial colorless phase of titration, the search interval for the absorbance derivative peak is limited to the position where the absorbance signal first significantly deviates from the baseline noise (satisfying...). ,in The baseline absorbance mean. The baseline standard deviation, The preset parameter ranges from 3 to 5, extending to the interval where the absorbance change rate falls back to the initial titration baseline. Within this interval, when... When the second threshold condition, local maximum characteristic, and peak width constraint are all met simultaneously, the corresponding titration volume is determined to be the second endpoint. ;like If the peak value is not significant, the ORP endpoint of the titration will be marked as a suspicious endpoint and maintenance or retesting will be prompted.

[0101] The two types of endpoints mentioned above may occur simultaneously or sequentially during a titration process. For example, in the titration volume... When the titrant mainly reacts with the component with the higher reaction rate, the ORP rises slowly and the solution shows no obvious color change; when When the volume reaches approximately 4 mL, the easily oxidized component is almost completely consumed, and the ORP shows a significant jump, forming the first endpoint. At this point, the absorbance signal exceeds the absorbance verification threshold. Subsequently, within the 4–8 mL range, the titrant continues to participate in the slow reaction of the difficult-to-oxidize component, and the color may change repeatedly while the ORP remains in the plateau region. When the volume reaches approximately 8 mL, the recalcitrant component is also completely oxidized. At this point, the change in ORP is insufficient to trigger a jump determination, but the derivative value of the absorbance signal satisfies endpoint condition two, thus forming a second endpoint. .

[0102] When only the titration process yields or In the case of two endpoints, the volume is directly used as the final titration endpoint; however, in the case of two endpoints, the system uses the volume difference between the two endpoints as the final titration endpoint. The size is used to determine the value. When When the error is less than the error threshold (e.g., 0.2 mL), the two endpoints can be considered as different sensor responses to the same chemical endpoint, and the average of the two volumes is used as the final endpoint; when When the value exceeds this threshold, it indicates that the two endpoints correspond to different reaction stages. This reflects the main components in the water sample that can be oxidized under standard conditions, therefore... As the final titration endpoint, and It is recorded only as an "indicator endpoint for difficult-to-oxidize substances" and is not used as a basis for calculating the permanganate index.

[0103] The following is for reference. Figure 4 It shows a schematic diagram of the structure of a computer system suitable for implementing the electronic device of the present application. Figure 4 The electronic device shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of this application.

[0104] like Figure 4 As shown, the computer system includes a CPU 401, which can perform various appropriate actions and processes based on a program stored in ROM 402 or a program loaded into RAM 403 from storage section 408. RAM 403 also stores various programs and data required for system operation. The CPU 401, ROM 402, and RAM 403 are interconnected via bus 404. Input / output (I / O) interface 405 is also connected to bus 404.

[0105] The following components are connected to I / O interface 405: an input section 406 including a keyboard, mouse, etc.; an output section 407 including a liquid crystal display (LCD) and speakers, etc.; a storage section 408 including a hard disk, etc.; and a communication section 409 including a network interface card such as a LAN card and a modem, etc. The communication section 409 performs communication processing via a network such as the Internet. A drive 410 is also connected to I / O interface 405 as needed. A removable medium 411, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on drive 410 as needed so that computer programs read from it can be installed into storage section 408 as needed.

[0106] Specifically, according to embodiments of this disclosure, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this disclosure include a computer program product comprising a computer program carried on a computer-readable storage medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication section 409, and / or installed from removable medium 411. When the computer program is executed by central processing unit (CPU) 401, it performs the functions defined in the methods of this application. It should be noted that the computer-readable storage medium of this application can be a computer-readable signal medium or a computer-readable storage medium, or any combination of the two. The computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this application, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in connection with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium may also be any computer-readable storage medium other than a computer-readable storage medium that can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. Program code contained on a computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0107] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof. Programming languages ​​include object-oriented programming languages—such as Java, Smalltalk, and C++—as well as conventional procedural programming languages—such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0108] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0109] The modules described in the embodiments of this application can be implemented in software or in hardware.

[0110] In another aspect, this application also provides a computer-readable storage medium, which may be included in the electronic device described in the above embodiments; or it may exist independently and not assembled into the electronic device. The computer-readable storage medium carries one or more programs, which, when executed by the electronic device, cause the electronic device to: acquire, in real-time and synchronously collect, the redox potential signal, absorbance signal, and temperature signal of the solution to be tested at the same measurement point; perform temperature drift compensation on the redox potential signal based on the temperature signal, and extract potential change characteristics based on the compensated redox potential signal, and determine the predicted titration volume range using the potential change characteristics; within the predicted titration volume range, in response to the potential change characteristics satisfying the endpoint determination condition one and the absorbance signal exceeding the absorbance verification threshold at this time, determine the titration volume corresponding to the potential change characteristics as the first titration volume. One endpoint; in response to the potential change feature satisfying endpoint determination condition one but the absorbance signal is less than the absorbance verification threshold, or the potential change feature not satisfying endpoint determination condition one, the absorbance change feature is extracted based on the absorbance signal, and when the absorbance change feature satisfies endpoint determination condition two, the corresponding titration volume is determined as the second endpoint; in response to obtaining only the first endpoint or only the second endpoint within the predicted titration volume range, the first endpoint or the second endpoint is used as the titration endpoint; in response to obtaining the first endpoint and the second endpoint respectively within the predicted titration volume range, the titration endpoint is determined based on the difference between the first endpoint and the second endpoint; the permanganate index of the test solution is calculated based on the titration endpoint.

[0111] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A method for online automatic determination of permanganate index, characterized in that, The method includes: S1, acquire the redox potential signal, absorbance signal and temperature signal of the solution to be tested in real time and synchronously at the same measurement point; S2, perform temperature drift compensation on the redox potential signal based on the temperature signal, extract potential change features based on the compensated redox potential signal, and use the potential change features to determine the predicted titration volume range; S3, within the predicted titration volume range, in response to the potential change feature satisfying endpoint determination condition one and the absorbance signal exceeding the absorbance verification threshold, the titration volume corresponding to the potential change feature is determined as the first endpoint; in response to the potential change feature satisfying endpoint determination condition one but the absorbance signal being less than the absorbance verification threshold, or the potential change feature not satisfying endpoint determination condition one, the absorbance change feature is extracted based on the absorbance signal, and when the absorbance change feature satisfies endpoint determination condition two, the corresponding titration volume is determined as the second endpoint; S4, in response to obtaining only the first endpoint or only the second endpoint within the predicted titration volume range, the first endpoint or the second endpoint is used as the titration endpoint; in response to obtaining the first endpoint and the second endpoint respectively within the predicted titration volume range, the titration endpoint is determined based on the difference between the first endpoint and the second endpoint. S5, Calculate the permanganate index of the test solution based on the titration endpoint; Step S2 further includes correcting the titration reaction rate based on the Arrhenius temperature correction factor to adjust the predicted titration volume range, and performing temperature correction on the original titration volume based on the Arrhenius temperature correction factor, resulting in a corrected titration volume. Determined according to the following relationship: ,in, For Arrhenius temperature correction factor, This refers to the raw titration volume collected in real time. During the titration process, the curves showing the changes in both the redox potential signal and the absorbance signal with the titration volume are based on the corrected titration volume. Perform construction and analysis; The predicted titration volume interval is determined based on the corresponding titration volume position according to a predicted rate of change threshold, and the predicted titration volume interval is determined based on the volume position. The predicted rate of change threshold is based on the first derivative of the redox potential signal after initial compensation during titration with respect to the titration volume. The weighted combination of the average value and its standard deviation is set.

2. The method for online automatic determination of permanganate index according to claim 1, characterized in that, The compensation relationship for the temperature drift compensation is as follows: In the formula, This is the temperature-corrected redox potential value. The potential reference value is at the reference temperature. This is the temperature compensation coefficient, with a value ranging from 1.0 to 3.0 mV / ℃. This refers to the solution temperature collected in real time during the titration process. This is a reference temperature.

3. The method for online automatic determination of permanganate index according to claim 1, characterized in that, The Arrhenius temperature correction factor satisfy: In the formula, The apparent activation energy of the reaction. The base of the natural logarithm, This is the universal gas constant. This refers to the solution temperature collected in real time during the titration process. This is a reference temperature.

4. The method for online automatic determination of permanganate index according to claim 1, characterized in that, The determination of the first endpoint includes: calculating the first derivative of the compensated redox potential signal as a function of titration volume. Within the predicted titration volume range, when the first derivative is detected... If a peak point 1 that satisfies endpoint determination condition 1 appears, and the absorbance signal corresponding to the peak point 1 exceeds the absorbance verification threshold, the titration volume corresponding to the peak point 1 is determined as the first endpoint.

5. The method for online automatic determination of permanganate index according to claim 1, characterized in that, The determination of the second endpoint includes: calculating the first derivative of the compensated redox potential signal as a function of titration volume. In response to the detection of the first derivative within the predicted titration volume range A peak point 1 that satisfies endpoint determination condition 1 appears, but the absorbance signal corresponding to the peak point 1 does not exceed the absorbance verification threshold; or the first derivative is not detected within the predicted titration volume range. If a peak point that satisfies endpoint determination condition one is found, calculate the first derivative of the absorbance signal as a function of titration volume. In response to the detection of the first derivative within the predicted titration volume range If a second peak point appears that satisfies the second endpoint determination condition, the titration volume corresponding to the second peak point is determined as the second endpoint.

6. The method for online automatic determination of permanganate index according to claim 5, characterized in that, Endpoint determination also includes: calculating the first derivative of the compensated redox potential signal as a function of titration volume. When the first derivative is detected within the predicted titration volume range If a peak point 1 that satisfies endpoint determination condition 1 is found, but the absorbance signal corresponding to peak point 1 does not exceed the absorbance verification threshold, calculate the first derivative of the absorbance signal as a function of titration volume. In response to the detection of the first derivative within the predicted titration volume range If no peak point two that meets the endpoint determination condition two appears, the titration volume corresponding to the peak point one is calibrated as a suspected endpoint.

7. The method for online automatic determination of permanganate index according to claim 1, characterized in that, The endpoint determination condition one is satisfied: In the formula, The ORP derivative value corresponding to peak point one. The first threshold, The ORP derivative value is the value corresponding to the sampling point preceding the peak point. This is the ORP derivative value corresponding to the next sampling point after the peak point; Wherein, the first derivative values ​​of at least two sampling points before and after the first peak point are higher than the preset ratio threshold of the first peak point, and the appearance of the first peak point is later than the time when the absorbance signal begins to rise.

8. The method for online automatic determination of permanganate index according to claim 1, characterized in that, The second endpoint determination condition is defined as simultaneously satisfying the following relationships: In the formula, This represents the absorbance derivative value corresponding to peak point two. The second threshold, This represents the absorbance derivative value corresponding to the sampling point preceding the peak point two. The absorbance derivative value corresponding to the next sampling point after the peak point; The search interval for peak point two is defined as the position where the absorbance signal first significantly deviates from the baseline noise until the absorbance change rate falls back to the baseline at the beginning of the titration. The position where the absorbance signal first significantly deviates from the baseline noise satisfies the following condition: In the formula, This represents the baseline mean absorbance at the initial stage of titration. The standard deviation of the absorbance signal during the baseline phase. These are preset parameters, with a value range of 2 to 5.

9. An online automatic determination system for permanganate index, characterized in that, The system for implementing the online automatic determination method of permanganate index as described in any one of claims 1-8 comprises: The signal acquisition module is configured to acquire, in real time, synchronously collect the redox potential signal, absorbance signal, and temperature signal of the solution to be tested; The potential change feature calculation module is configured to perform temperature drift compensation on the redox potential signal based on the temperature signal, extract potential change features based on the compensated redox potential signal, and use the potential change features to determine the predicted titration volume range. An endpoint determination module is configured to, within the predicted titration volume range, determine the titration volume corresponding to the potential change feature as the first endpoint when the potential change feature satisfies endpoint determination condition one and the absorbance signal exceeds the absorbance verification threshold; and when the potential change feature satisfies endpoint determination condition one but the absorbance signal is less than the absorbance verification threshold, or the potential change feature does not satisfy endpoint determination condition one, extract the absorbance change feature based on the absorbance signal, and determine the corresponding titration volume as the second endpoint when the absorbance change feature satisfies endpoint determination condition two. An endpoint decision module is configured to, in response to obtaining only the first endpoint or only the second endpoint within the predicted titration volume range, use the first endpoint or the second endpoint as the titration endpoint; and in response to obtaining both the first endpoint and the second endpoint within the predicted titration volume range, determine the titration endpoint based on the difference between the first endpoint and the second endpoint. The permanganate index calculation module is configured to calculate the permanganate index of the test solution based on the titration endpoint. The signal acquisition module includes a hollow rod-shaped probe housing and an optical detection unit, a redox potential measurement unit, and a temperature sensing unit integrated within the probe housing. The end of the probe housing is provided with a measurement window area that communicates with the external solution to be tested. The measurement positions of the optical detection unit, the redox potential measurement unit, and the temperature sensing unit are all located within the end area of ​​the probe housing corresponding to the measurement window area. Step S2 further includes correcting the titration reaction rate based on the Arrhenius temperature correction factor to adjust the predicted titration volume range, and performing temperature correction on the original titration volume based on the Arrhenius temperature correction factor, resulting in a corrected titration volume. Determined according to the following relationship: ,in, For Arrhenius temperature correction factor, This refers to the raw titration volume collected in real time. During the titration process, the curves showing the changes in both the redox potential signal and the absorbance signal with the titration volume are based on the corrected titration volume. Perform construction and analysis; The predicted titration volume interval is determined based on the corresponding titration volume position according to a predicted rate of change threshold, and the predicted titration volume interval is determined based on the volume position. The predicted rate of change threshold is based on the first derivative of the redox potential signal after initial compensation during titration with respect to the titration volume. The weighted combination of the average value and its standard deviation is set.

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