Device and method for detecting permanganate index in water

Abstract

The invention relates to a photoelectric detection technology, and particularly provides a device and a method for detecting the permanganate index in water, the detection device comprises a multi-channel direction selection valve; the quantifying unit is connected with the common end of the multi-channel direction selection valve and is used for extracting, quantifying and pushing out liquid; the reagent comprises a potassium permanganate solution, an acid solution, a sodium oxalate solution and a water sample which are respectively communicated with ports of the multi-channel direction selection valve; an inlet of the reaction container is communicated with a port of the multi-channel direction selection valve, and the heating module is used for heating liquid in the reaction container; the valves are respectively arranged at two ends of the reaction container; the optical detection unit comprises a light source, a detector and an analysis module, the detector is used for converting measurement light which penetrates through the reaction container and is emitted by the light source into an electric signal and sending the electric signal to the analysis module, and the analysis module outputs absorbance and obtains the concentration of the permanganate index in the water sample according to the absorbance. The method has the advantages of accurate detection and the like, and is applied to water quality detection.

Description

Technical Field

[0001] The present invention relates to optoelectronic detection technology, and particularly to a device and method for detecting the permanganate index in water. Background Art

[0002] The permanganate index in water quality is an index reflecting the oxidizable substances, both organic and inorganic, in water bodies. It is one of the parameters for evaluating the quality of surface water, and is of great significance for reflecting the water pollution status. It is a routine monitoring item for water quality monitoring in China.

[0003] Currently, the following are several commonly used methods for detecting the permanganate index.

[0004] 1. Direct colorimetric method: By digesting with acidic potassium permanganate, the degree of fading of potassium permanganate is measured to determine the amount of reducing substances in water.

[0005] This method is extremely susceptible to the acidity and temperature of the reaction system, and there is interference from manganese dioxide precipitation in the detection. Therefore, when measuring actual water samples or glucose solutions, the digestion efficiency is inconsistent with that of the sodium oxalate standard solution, affecting the accuracy of the measurement.

[0006] 2. Colorimetric titration method: In the national standard, sodium oxalate can reduce the remaining potassium permanganate as well as manganese dioxide. Therefore, the colorimetric titration method can reduce the interference of manganese dioxide.

[0007] This method has a long heating time and a large error in judging the titration end point. As the titration process progresses, a certain degree of dilution will occur, and the measurement results are affected by the reaction time, temperature and conditions, resulting in a large error in the determination of the permanganate index, and the oxidation rates of water samples with different concentrations are different. In addition, the titration process is affected by the environment and is prone to fluctuations in the detection signal value. Therefore, it increases the difficulty of accurately measuring the permanganate index in water online.

[0008] 3. Electrode titration method: The potentiometric titration method judges the end point through the oxidation-reduction potential of the solution. However, the titration process is affected by temperature and the titration process is lengthy; there are high requirements for the stability of the electrode.

[0009] With the development of instrumental analysis, there are higher requirements for the accuracy and timeliness of detection, and there is an urgent need for a simple, rapid and accurate detection method. Summary of the Invention

[0010] To solve the deficiencies in the above-mentioned existing technical solutions, the present invention provides a device for detecting the permanganate index in water with good accuracy and high efficiency.

[0011] The object of the present invention is achieved by the following technical solutions:

[0012] A device for detecting the permanganate index in water, comprising a multi-channel selector valve; the detection device further comprises:

[0013] A quantitative unit, which is connected to the common end of the multi-channel selector valve and is used for extracting, quantifying and ejecting liquid;

[0014] Reagents, which include potassium permanganate solution, acid solution, sodium oxalate solution and water sample, and are respectively communicated with the ports of the multi-channel selector valve;

[0015] A reaction vessel and a heating module, the inlet of the reaction vessel is communicated with the port of the multi-channel selector valve, and the heating module is used for heating the liquid in the reaction vessel;

[0016] Valves, which are respectively arranged at both ends of the reaction vessel;

[0017] An optical detection unit, which includes a light source, a detector and an analysis module. The detector is used for converting the measurement light emitted by the light source passing through the reaction vessel into an electrical signal and sending it to the analysis module. The analysis module outputs the absorbance and obtains the concentration of the permanganate index in the water sample according to the absorbance.

[0018] The purpose of the present invention also lies in providing a method for detecting the permanganate index in water with good accuracy and high efficiency, and this purpose of the invention is achieved through the following technical solutions.

[0019] A method for detecting the permanganate index in water, comprising the following steps:

[0020] (A1) The multi-channel selector valve is switched, and the quantitative unit sucks, quantifies and ejects the water sample. The water sample passes through the multi-channel selector valve and enters the reaction vessel;

[0021] (A2) The multi-channel selector valve is switched, and the quantitative unit sucks, quantifies and ejects the acid solution. The acid solution passes through the multi-channel selector valve and enters the reaction vessel;

[0022] (A3) The multi-channel selector valve is switched, and the quantitative unit sucks, quantifies and ejects the potassium permanganate solution. The potassium permanganate solution passes through the multi-channel selector valve and enters the reaction vessel;

[0023] (A4) Both ends of the reaction vessel are closed, and the liquid in the reaction vessel is heated to digest the water sample;

[0024] (A5) The multi-channel selector valve is switched, and the quantitative unit sucks, quantifies and ejects the sodium oxalate solution. The sodium oxalate solution passes through the multi-channel selector valve and enters the reaction vessel;

[0025] Record the light intensity L1 of the solution at 525 nm;

[0026] (A6) The multi-channel directional valve switches, and the metering unit sucks, meters, and ejects the permanganate solution. The permanganate solution passes through the multi-channel directional valve and enters the reaction vessel;

[0027] Record the light intensity L2 of the solution at 525 nm;

[0028] (A7) Obtain the absorbance A based on the light intensity L1 and the light intensity L2;

[0029] (A8) Use the mapping relationship to obtain the concentration of the permanganate index in the water sample.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] This application uses acidic potassium permanganate oxidation and secondary redox, and then detects the remaining amount of potassium permanganate by colorimetry (non-direct colorimetry). Within the allowable error range, the concentration of the permanganate index in the water sample and the absorbance are linearly negatively correlated.

[0032] This method is simple to operate and avoids the influence of manganese dioxide precipitation introduced by the direct colorimetry method.

[0033] There is no need for titration, which greatly shortens the detection time and improves the detection efficiency. It can be widely applied to various scenarios such as laboratories and emergency monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Referring to the accompanying drawings, the disclosure of the present invention will become more understandable. It is easy for those skilled in the art to understand that these drawings are only used to illustrate the technical solutions of the present invention and are not intended to limit the protection scope of the present invention. In the drawings:

[0035] Figure 1 is a schematic structural diagram of a device for detecting the permanganate index in water according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] Figure 1 The following description and examples describe alternative specific embodiments of the present invention to teach those skilled in the art how to implement and reproduce the present invention. To teach the technical solutions of the present invention, some conventional aspects have been simplified or omitted. Those skilled in the art should understand that variations or substitutions derived from these specific embodiments will fall within the scope of the present invention. Those skilled in the art should understand that the following features can be combined in various ways to form multiple variations of the present invention. Thus, the present invention is not limited to the following alternative specific embodiments, but is defined only by the claims and their equivalents.

[0037] Example 1.

[0038] A device for detecting the permanganate index in water according to this embodiment, as Figure 1 shown, includes:

[0039] Multi-channel directional valve 11;

[0040] The metering unit 21 is connected to the common end of the multi-channel directional valve 11 and is used for extracting, metering and ejecting liquids, such as water samples, reagents and standard solutions, etc.;

[0041] The reagent 52 includes an acid solution, a potassium permanganate solution and a sodium oxalate solution, and is respectively connected to the ports of the multi-channel directional valve 11;

[0042] The inlet of the reaction vessel 31 is connected to the port of the multi-channel directional valve 11, and the heating module is used to heat the liquid in the reaction vessel 31;

[0043] Valve 41, the valve 41 is respectively arranged at both ends of the reaction vessel 31;

[0044] Optical detection unit, the optical detection unit includes a light source 71, a detector 72 and an analysis module. The detector 72 is used to convert the measurement light emitted by the light source 71 passing through the reaction vessel 11 into an electrical signal and send it to the analysis module. The analysis module outputs the absorbance and obtains the concentration of permanganate index in the water sample according to the absorbance.

[0045] In order to improve the detection accuracy and detection efficiency, further, the ports of the multi-channel directional valve 11 are also connected to the outside air and standard solutions 61 of permanganate with different concentrations.

[0046] A method for detecting permanganate index in water according to an embodiment of the present invention includes the following steps:

[0047] (A1) The multi-channel directional valve 11 is switched, the metering unit 21 sucks, meters and ejects the water sample, and the water sample passes through the multi-channel directional valve 11 and enters the reaction vessel 31;

[0048] (A2) The multi-channel directional valve 11 is switched, the metering unit 21 sucks, meters and ejects the acid solution, and the acid solution passes through the multi-channel directional valve 11 and enters the reaction vessel 31;

[0049] (A3) The multi-channel directional valve 11 is switched, the metering unit 21 sucks, meters and ejects the permanganate solution, and the permanganate solution passes through the multi-channel directional valve 11 and enters the reaction vessel 31;

[0050] (A4) Both ends of the reaction vessel 31 are closed, and the liquid in the reaction vessel 31 is heated for digestion of the water sample;

[0051] (A5) The multi-channel directional valve 11 is switched, the metering unit 21 sucks, meters and ejects the sodium oxalate solution, and the sodium oxalate solution passes through the multi-channel directional valve 11 and enters the reaction vessel 31;

[0052] Record the light intensity L1 of the solution at 525 nm;

[0053] (A6) The multi-channel directional valve 11 is switched, and the metering unit 21 aspirates, meters, and discharges the permanganate solution. The permanganate solution passes through the multi-channel directional valve 11 and enters the reaction vessel 31;

[0054] Record the light intensity L2 of the solution at 525 nm;

[0055] (A7) Obtain the absorbance A based on the light intensity L1 and the light intensity L2;

[0056] (A8) Obtain the concentration of the permanganate index in the water sample using the mapping relationship.

[0057] To improve the detection accuracy and detection efficiency, further, in step (A2), step (A3), step (A4), and step (A6), after the reagent is introduced into the reaction vessel, the multi-channel directional valve is switched, and the metering unit aspirates and discharges air. The air passes through the multi-channel directional valve and enters the reaction vessel, stirring the solution.

[0058] To accurately obtain the mapping relationship, further, the way to obtain the mapping relationship is as follows:

[0059] The multi-channel directional valve 11 is switched, and the metering unit 21 aspirates, meters, and discharges standard solutions with different permanganate concentrations. The standard solutions pass through the multi-channel directional valve 11 and enter the reaction vessel 31;

[0060] According to the method of step (A2) - step (A7), obtain the absorbances corresponding to the standard solutions with different permanganate concentrations;

[0061] Establish and save the mapping relationship between the permanganate index concentration and the absorbance.

[0062] To eliminate cross-interference and ensure the detection accuracy, further, the detection method further includes the steps:

[0063] (A9) The multi-channel directional valve is switched, and the metering unit aspirates and discharges pure water. The pure water passes through the multi-channel directional valve and enters and cleans the reaction vessel;

[0064] Discharge the pure water in the reaction vessel.

[0065] Example 2:

[0066] An application example of the device and method for detecting the permanganate index in water according to Embodiment 1 of the present invention.

[0067] In this application example, as Figure 1As shown, the ports of the multi-channel directional valve 11 are respectively connected to the reaction vessel 31, various reagents 52, water sample 51, pure water 62, potassium permanganate standard solutions 61 with different concentration gradients, and the external air, and the common port is connected to the metering unit 21. The valve group 81 is used to selectively connect the pure water 62 and the potassium permanganate solutions with different concentrations to the metering unit 21. The metering unit 21 uses a piston pump.

[0068] An electric heating wire is wound around the outside of the reaction vessel 31, and the temperature control module is used to control the temperature of the liquid in the reaction vessel 31. The valve 41 is an electromagnetic valve and is arranged at the upper and lower openings of the reaction vessel 31.

[0069] A method for detecting the permanganate index in water according to an embodiment of the present invention includes the following steps:

[0070] (A1) The valve 41 is opened, the multi-channel directional valve 11 is switched, the metering unit 21 sucks, measures, and ejects the water sample, and the water sample passes through the multi-channel directional valve 11 and enters the reaction vessel 31.

[0071] (A2) The valve 41 is opened, the multi-channel directional valve 11 is switched, the metering unit 21 sucks, measures, and ejects the sulfuric acid solution, and the sulfuric acid solution passes through the multi-channel directional valve 11 and enters the reaction vessel 31.

[0072] The valve 41 is opened, the multi-channel directional valve 11 is switched, the metering unit 21 sucks and ejects air, and the air passes through the multi-channel directional valve 11 and enters the reaction vessel 31, stirring the mixed solution to fully mix the acid solution and the water sample.

[0073] (A3) The valve 41 is opened, the multi-channel directional valve 11 is switched, the metering unit 21 sucks, measures, and ejects the potassium permanganate solution, and the potassium permanganate solution passes through the multi-channel directional valve 11 and enters the reaction vessel 31.

[0074] The valve 41 is opened, the multi-channel directional valve 11 is switched, the metering unit 21 sucks and ejects air, and the air passes through the multi-channel directional valve 11 and enters the reaction vessel 31, stirring the mixed solution to fully mix various solutions and the water sample.

[0075] (A4) The valve 41 is closed, both ends of the reaction vessel 31 are sealed, and the liquid in the reaction vessel 31 is heated using the heating wire until the temperature reaches 99 degrees and is heated for 10 minutes to digest the water sample. Based on the design of the valve 41, the temperature can be greater than 100 degrees, such as temperature = 99 degrees + (altitude / 1000) degrees, so that it can be applied in high-altitude areas.

[0076] (A5) The valve 41 is opened, the multi-channel directional valve 11 is switched, the metering unit 21 sucks, measures, and ejects the sodium oxalate solution, and the excessive sodium oxalate solution passes through the multi-channel directional valve 11 and enters the reaction vessel 31.

[0077] Valve 41 is opened, the multi-channel directional valve 11 is switched, the metering unit 21 sucks and ejects air, the air passes through the multi-channel directional valve 11 and enters the reaction vessel 31, stirring the mixed solution.

[0078] The light source 71 emits 525 nm measurement light, the measurement light passes through the reaction vessel 31, the detector 72 receives the transmitted light, and the light intensity L1 of the solution at 525 nm is obtained as the reference light intensity.

[0079] (A6) Valve 41 is opened, the multi-channel directional valve 11 is switched, the metering unit 21 sucks, meters and ejects potassium permanganate solution, and the excess potassium permanganate solution passes through the multi-channel directional valve 11 and enters the reaction vessel 31.

[0080] Valve 41 is opened, the multi-channel directional valve 11 is switched, the metering unit 21 sucks and ejects air, the air passes through the multi-channel directional valve 11 and enters the reaction vessel 31, stirring the mixed solution.

[0081] The light source 71 emits 525 nm measurement light, the measurement light passes through the reaction vessel 31, the detector 72 receives the transmitted light, and the light intensity L2 of the solution at 525 nm is obtained as the sample light intensity.

[0082] (A7) The absorbance A is obtained based on the light intensity L1 and the light intensity L2, and the obtaining method is the existing technology in the field.

[0083] (A8) The concentration of permanganate index in the water sample is obtained using the mapping relationship.

[0084] (A9) The multi-channel directional valve 11 is switched, the metering unit 21 sucks and ejects pure water 62, and the pure water 62 passes through the multi-channel directional valve 11 and enters and cleans the reaction vessel 31;

[0085] The pure water 62 in the reaction vessel 31 is discharged.

[0086] The manner of the mapping relationship is as follows:

[0087] The multi-channel directional valve 11 and the valve group 81 are switched, the metering unit 21 sucks, meters and ejects potassium permanganate standard solutions 61 with different concentrations, and the standard solutions pass through the multi-channel directional valve 11 and enter the reaction vessel 31;

[0088] According to the method of step (A2) - step (A7), the absorbances corresponding to the standard solutions with different permanganate concentrations are obtained;

[0089] The mapping relationship between the permanganate index concentration and the absorbance is established and saved.

Claims

1. A detection device for permanganate index in water, comprising a multi-channel directional valve; characterized in that, The detection device further includes: A quantification unit, which is connected to the common end of the multi-channel selection valve and is used for extracting, quantifying, and ejecting liquid; Reagents, which include potassium permanganate solution, acid solution, sodium oxalate solution, and water sample, and are respectively connected to the ports of the multi-channel selection valve; A reaction vessel and a heating module, the inlet of the reaction vessel is connected to the port of the multi-channel selection valve, and the heating module is used for heating the liquid in the reaction vessel; Valves, which are respectively arranged at both ends of the reaction vessel; An optical detection unit, which includes a light source, a detector, and an analysis module. The detector is used for converting the measurement light emitted by the light source passing through the reaction vessel into an electrical signal and sending it to the analysis module. The analysis module outputs the absorbance and obtains the concentration of permanganate index in the water sample according to the absorbance.

2. The detection device according to claim 1, wherein The ports of the multi-channel selection valve are also connected to the external air and standard solutions of permanganate with different concentrations.

3. The detection device according to claim 1, wherein The quantification unit uses a metering pump.

4. A method for detecting permanganate index in water, comprising the following steps: (A1) Switch the multi-channel selection valve, and the quantification unit sucks, quantifies, and ejects the water sample. The water sample passes through the multi-channel selection valve and enters the reaction vessel; (A2) Switch the multi-channel selection valve, and the quantification unit sucks, quantifies, and ejects the acid solution. The acid solution passes through the multi-channel selection valve and enters the reaction vessel; (A3) Switch the multi-channel selection valve, and the quantification unit sucks, quantifies, and ejects the permanganate solution. The permanganate solution passes through the multi-channel selection valve and enters the reaction vessel; (A4) Seal both ends of the reaction vessel and heat the liquid in the reaction vessel to digest the water sample; (A5) Switch the multi-channel selection valve, and the quantification unit sucks, quantifies, and ejects the sodium oxalate solution. The sodium oxalate solution passes through the multi-channel selection valve and enters the reaction vessel; Record the light intensity L1 of the solution at 525 nm; (A6) Switch the multi-channel selection valve, and the quantification unit sucks, quantifies, and ejects the permanganate solution. The permanganate solution passes through the multi-channel selection valve and enters the reaction vessel; Record the light intensity L2 of the solution at 525 nm; (A7) Obtain the absorbance A according to the light intensity L1 and the light intensity L2; (A8) Use the mapping relationship to obtain the concentration of permanganate index in the water sample.

5. The detection method according to claim 4, wherein In steps (A2), (A3), (A4), and (A6), after the reagent is introduced into the reaction vessel, the multi-channel selection valve is switched, and the quantification unit sucks and ejects air. The air passes through the multi-channel selection valve and enters the reaction vessel to stir the solution.

6. The detection method according to claim 4, wherein The way to obtain the mapping relationship is: Switch the multi-channel selection valve, and the quantification unit sucks, quantifies, and ejects standard solutions with different permanganate concentrations. The standard solutions pass through the multi-channel selection valve and enter the reaction vessel; According to the method of steps (A2)-(A7), obtain the absorbance corresponding to the standard solutions with different permanganate concentrations; Establish a mapping relationship between the permanganate index concentration and the absorbance and save it.

7. The detection method according to claim 4, wherein The detection method further includes the step: (A9) Switch the multi-channel selection valve, and the quantification unit sucks and ejects pure water. The pure water passes through the multi-channel selection valve and enters and cleans the reaction vessel; Discharge the pure water in the reaction vessel.

8. The detection method according to claim 4, characterized in that In step (A5), an excessive amount of sodium oxalate solution is added, and in step (A6), an excessive amount of permanganate solution is added.

9. The detection method according to claim 4, characterized in that The acid solution used is sulfuric acid solution, and the permanganate solution used is potassium permanganate solution.

10. The detection method according to claim 4, characterized in that, The metering unit uses a metering pump.

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