CN115615976A - Water quality chemical oxygen demand detection method based on laser spectrum technology - Google Patents

Water quality chemical oxygen demand detection method based on laser spectrum technology Download PDF

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CN115615976A
CN115615976A CN202211259745.0A CN202211259745A CN115615976A CN 115615976 A CN115615976 A CN 115615976A CN 202211259745 A CN202211259745 A CN 202211259745A CN 115615976 A CN115615976 A CN 115615976A
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fluorescence
spectrum
laser
cod
oxygen demand
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田兆硕
车潇华
毕宗杰
刘情操
孙烽豪
朱东杰
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Shandong Ship Technology Research Institute
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/65—Raman scattering
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/64—Fluorescence; Phosphorescence
    • G01N21/6402—Atomic fluorescence; Laser induced fluorescence
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/20—Controlling water pollution; Waste water treatment

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Abstract

The invention provides a water quality chemical oxygen demand detection method based on a laser spectrum technology, which comprises the following steps of 1, enabling laser to be incident into a detected water sample, and enabling the detected water sample to be excited by the laser to generate an optical signal; step 2, receiving the optical signal through a spectrometer, converting the optical signal into an electric signal and further converting the electric signal into a digital signal; step 3, receiving the digital signals through a data processing system to form a spectrum curve; step 4, calculating the relative integral fluorescence intensity I according to the information in the spectral curve T ，
Figure DDA0003891108170000011
λ 1 、λ 2 Respectively the start and end position wavelengths of the fluorescence spectrum, where I λ represents the fluorescence intensity at the wavelength λ, I r Indicating raman peak buckleLight intensity after removing the fluorescence background; step 5, calculating the COD value of the detected water sample according to a water quality chemical oxygen demand formula, wherein the water quality chemical oxygen demand formula is COD = KI T + C. The detection method can reduce the influence of various interference factors on the COD detection result to a great extent, and has the advantages of high sensitivity, high measurement speed, convenient measurement and high accuracy.

Description

Method for detecting chemical oxygen demand of water based on laser spectrum technology
Technical Field
The invention relates to the technical field of water quality chemical oxygen demand detection, in particular to a water quality chemical oxygen demand detection method based on a laser spectrum technology.
Background
The water quality analysis is an important task for environmental monitoring, and the Chemical Oxygen Demand (COD) value reflects the concentration of reducing substances in water, is an important index for measuring organic matter pollution in water and is one of important measurement items in the water quality monitoring analysis. Most of the traditional water quality COD detection methods adopt chemical analysis methods, including potassium dichromate method (COD) Cr ) And potassium permanganate method (COD) Mn ) However, the method has the problems of long measurement period, more required chemical reagents, secondary pollution and the like, and the requirement of real-time detection of water quality is difficult to meet. Compared with the chemical method, the optical analysis method is based on substance characteristic spectrum, has the advantages of high analysis speed, simple and convenient operation, good selectivity, high sensitivity, no damage to samples and the like, is rapidly developed in the field of online water quality monitoring, and is increasingly paid attention to by people.
The three-dimensional fluorescence spectrometry has the characteristics of large spectrum data volume, high sensitivity and the like in water quality detection, but has the defects of low detection speed and complex operation, and is not easy to perform rapid on-line analysis on water quality. Compared with the three-dimensional fluorescence spectroscopy, the two-dimensional fluorescence spectroscopy uses laser with single wavelength or LED as an excitation light source, simplifies a measuring device, has higher analysis speed because only two-dimensional spectral curves are analyzed, and researchers at home and abroad begin to apply the two-dimensional fluorescence spectroscopy to rapid water quality detection in recent years.
At present, although the two-dimensional fluorescence spectrometry can realize the measurement of COD parameters by analyzing fluorescence intensity, due to the influence of factors such as environmental light change, water flow fluctuation, instrument vibration and light source aging, the problems of unstable measured data, low accuracy and the like exist in practical application.
Disclosure of Invention
In order to solve the problems in the prior art, the application provides a water quality chemical oxygen demand detection method based on a laser spectrum technology so as to reduce the influence of various interference factors on a COD detection result to a great extent, and the method has the advantages of high sensitivity, high measurement speed, convenience in measurement and high accuracy.
In order to achieve the purpose, the application provides a water quality chemical oxygen demand detection method based on a laser spectrum technology, which comprises the following steps:
step 1, enabling laser to be incident into a water sample to be detected, wherein the water sample to be detected is excited by the laser to generate an optical signal;
step 2, receiving the optical signal generated in the step 1 through a spectrometer, converting the optical signal into an electric signal and further converting the electric signal into a digital signal;
and 3, receiving the digital signal transmitted by the spectrometer through a data processing system to form a spectrum curve, wherein the spectrum curve comprises a Raman scattering peak of water and a fluorescence peak of dissolved organic matters in the water, and the light intensity of the Raman peak after the fluorescence background is subtracted is I r Representing;
step 4, calculating the relative integral fluorescence intensity I according to the information in the spectral curve T Wherein, in the step (A),
Figure BDA0003891108150000021
in the formula, λ 1 Is the starting position wavelength, lambda, of the fluorescence spectrum 2 Is the wavelength of the end position of the fluorescence spectrum, I λ represents the fluorescence intensity at the wavelength λ, I r Representing the light intensity of the Raman peak after deducting the fluorescence background;
step 5, calculating the COD value of the detected water sample according to a water quality chemical oxygen demand formula, wherein the water quality chemical oxygen demand formula is COD = KI T + C, wherein I T The relative integral fluorescence intensity calculated in step 4, K is a proportionality coefficient, C is a detection limit, and K and C are normalNumber, relative integral fluorescence intensity I using standard solution T The correlation with the COD value detected by the national standard method can obtain the values of K and C.
In some embodiments, in the step 5, the value obtaining process of K and C includes the following steps:
step 501, mixing a glucose solution and a sodium humate solution with the same volume to serve as a standard solution, wherein the concentration ratio of the glucose solution to the sodium humate solution is 1;
502, selecting a standard solution with any concentration ratio in the step 501;
step 503, enabling laser to enter the standard solution, wherein the standard solution is excited by the laser to generate an optical signal;
step 504, receiving the optical signal generated in the step 503 through a spectrometer, converting the optical signal into an electrical signal, and further converting the electrical signal into a digital signal;
505, receiving the digital signal transmitted by the spectrometer through a data processing system to form a spectrum curve;
step 506, calculating the relative integral fluorescence intensity I according to the information in the spectral curve T Wherein, in the process,
Figure BDA0003891108150000031
in the formula, λ 1 Is the starting position wavelength, lambda, of the fluorescence spectrum 2 Is the wavelength of the end position of the fluorescence spectrum, I λ represents the fluorescence intensity at the wavelength λ, I r Representing the light intensity of the Raman peak after deducting the fluorescence background;
step 507, detecting the COD value of the standard solution by adopting a national standard method and the I value obtained in the step 506 T The values form a set of data;
step 508, diluting the standard solution in step 502 at least once, repeating the steps 503-507 for the standard solution diluted each time, and obtaining a plurality of groups of relative integral fluorescence intensity I T Value and COD value;
509, several sets of acquired relative integrated fluorescence intensities I T Substituting the value and the COD value into a formula COD = KI T And + C, calculating values of K and C by a least square method.
The beneficial effects of the scheme of the application lie in that the above-mentioned quality of water chemical oxygen demand detection method based on laser spectroscopy adopts the mixed solution of sodium humate solution and glucose solution as the standard solution of spectrum method detection COD, utilizes the relative integral fluorescence intensity I of standard solution T The values of K and C can be obtained by correlating with the COD value detected by the national standard method, and then the chemical oxygen demand formula COD = KI of the water quality is utilized T + C calculating the COD value of the water sample to be measured, wherein
Figure BDA0003891108150000032
The detection method can reduce the influence of various interference factors on the COD detection result to a great extent, and has the advantages of high sensitivity, high measurement speed, convenient measurement and high accuracy.
Drawings
FIG. 1 is a flow chart of a method for detecting chemical oxygen demand of water based on a laser spectroscopy technology in an embodiment.
Fig. 2 shows a schematic diagram of a typical spectral curve generated by laser light incident on a measured water sample in the embodiment.
FIG. 3 is a graph showing the COD value of the standard solution in the examples as a function of the relative integrated fluorescence intensity.
Detailed Description
The following further describes embodiments of the present application with reference to the drawings.
As shown in fig. 1, the method for detecting chemical oxygen demand of water quality based on laser spectroscopy comprises the following steps:
step 1, enabling laser to enter a water sample to be detected, and enabling the water sample to be detected to be excited by the laser to generate an optical signal.
And 2, receiving the optical signal generated in the step 1 through a spectrometer, converting the optical signal into an electric signal and further converting the electric signal into a digital signal.
Step 3, receiving the digital signal transmitted by the spectrometer through a data processing system (such as a computer) to formThe spectral curve, as shown in FIG. 2, includes the rice scattering peak (intensity is expressed as I) of the suspended particles in water S Expressed as I), raman scattering peak of water (intensity is expressed as I) R Indicated), fluorescence peak of Dissolved Organic Matter (DOM) in water (intensity is represented by I) F Expressed) with the light intensity of the Raman peak after subtraction of the fluorescence background is represented by I r And (4) showing.
Step 4, calculating the relative integral fluorescence intensity I according to the information in the spectral curve T Wherein, in the step (A),
Figure BDA0003891108150000041
in the formula of lambda 1 Is the starting position wavelength, lambda, of the fluorescence spectrum 2 Is the wavelength of the end position of the fluorescence spectrum, I λ represents the fluorescence intensity at the wavelength λ, I r Indicating the intensity of the raman peak after subtraction of the fluorescent background.
Because the fluorescence spectral range that organic matter produced in the laser excitation surveyed water sample is wider, for the fluorescence contribution of organic matter in the comprehensive reaction water, adopt the relative integral fluorescence intensity to calculate the COD parameter in the aquatic in this patent application to improve the degree of accuracy that detects.
Step 5, calculating the COD value of the detected water sample according to a water quality chemical oxygen demand formula, wherein the water quality chemical oxygen demand formula is COD = KI T + C, wherein I T Using the relative integral fluorescence intensity I of the standard solution as the relative integral fluorescence intensity calculated in step 4, K is a proportionality coefficient, C is a detection limit, and K and C are constants T The correlation with the COD value detected by the national standard method can obtain the values of K and C.
Specifically, the K and C value acquisition process includes the following steps:
step 501, mixing a glucose solution and a sodium humate solution with the same volume to serve as a standard solution, wherein the concentration ratio of the glucose solution to the sodium humate solution is 1. In this example, the same volume of glucose solution and sodium humate solution was used as the standard solution in order to match the laser-induced fluorescence intensity of the standard solution with the fluorescence intensity of an actual water sample.
And 502, selecting the standard solution at any concentration ratio in the step 501.
And step 503, enabling laser to enter the standard solution, wherein the standard solution is excited by the laser to generate an optical signal.
Step 504, receiving the optical signal generated in step 503 by a spectrometer, converting the optical signal into an electrical signal, and further converting the electrical signal into a digital signal.
And 505, receiving the digital signal transmitted by the spectrometer through a data processing system to form a spectrum curve.
Step 506, calculating the relative integral fluorescence intensity I according to the information in the spectral curve T Wherein, in the step (A),
Figure BDA0003891108150000051
in the formula of lambda 1 Is the starting position wavelength, lambda, of the fluorescence spectrum 2 Is the wavelength of the end position of the fluorescence spectrum, I λ represents the fluorescence intensity at the wavelength λ, I r Indicating the intensity of the raman peak after subtraction of the fluorescent background.
Step 507, detecting the COD value of the standard solution by adopting a national standard method and the I value obtained in the step 506 T The values form a set of data.
Step 508, diluting the standard solution in step 502 at least once, repeating the steps 503-507 for the standard solution diluted each time, and obtaining a plurality of groups of relative integral fluorescence intensity I T Value and COD value.
509, several sets of acquired relative integrated fluorescence intensities I T Substituting the value and COD value into the formula COD = KI T + C, the values of K and C are calculated by the least squares method, as shown in FIG. 3.
The application relates to a method for detecting chemical oxygen demand of water quality based on a laser spectrum technology, which adopts a mixed solution of a sodium humate solution and a glucose solution as a standard solution for detecting COD by a spectrum method, and utilizes the relative integral fluorescence intensity I of the standard solution T The values of K and C can be obtained by correlating with the COD value detected by the national standard method, and then the chemical oxygen demand formula COD = KI of the water quality is utilized T + C calculating the COD value of the water sample to be measuredIn which
Figure BDA0003891108150000061
The method can reduce the influence of various interference factors on the COD detection result to a great extent, and has the advantages of high sensitivity, high measurement speed, convenient measurement and high accuracy.
The above description is only for the preferred embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can substitute or change the technical solution of the present application and its concept within the technical scope of the present application, and shall be covered by the scope of the present application.

Claims (2)

1. A water quality chemical oxygen demand detection method based on a laser spectrum technology is characterized by comprising the following steps: the method comprises the following steps:
step 1, enabling laser to be incident into a water sample to be detected, wherein the water sample to be detected is excited by the laser to generate an optical signal;
step 2, receiving the optical signal generated in the step 1 through a spectrometer, converting the optical signal into an electric signal and further converting the electric signal into a digital signal;
and 3, receiving the digital signal transmitted by the spectrometer through a data processing system to form a spectrum curve, wherein the spectrum curve comprises a Raman scattering peak of water and a fluorescence peak of dissolved organic matters in the water, and the light intensity of the Raman peak after the fluorescence background is subtracted is I r Represents;
step 4, calculating the relative integral fluorescence intensity I according to the information in the spectral curve T Wherein, in the step (A),
Figure FDA0003891108140000011
in the formula of lambda 1 Is the starting position wavelength, lambda, of the fluorescence spectrum 2 Is the wavelength of the end position of the fluorescence spectrum, I λ represents the fluorescence intensity at the wavelength λ, I r Representing the light intensity of the Raman peak after deducting the fluorescence background;
step 5, according to the chemical oxygen demand of water qualityCalculating the COD value of the detected water sample according to the formula, wherein the chemical oxygen demand formula of the water quality is COD = KI T + C, wherein I T Using the relative integral fluorescence intensity I of the standard solution as the relative integral fluorescence intensity calculated in step 4, K being a proportionality coefficient, C being a detection limit, and K and C being constants T The correlation with the COD value detected by the national standard method can obtain the values of K and C.
2. The method for detecting the chemical oxygen demand of water quality based on the laser spectrum technology as claimed in claim 1, wherein: in the step 5, the value obtaining process of K and C includes the following steps:
step 501, mixing a glucose solution and a sodium humate solution with the same volume to serve as a standard solution, wherein the concentration ratio of the glucose solution to the sodium humate solution is 1-1;
502, selecting a standard solution at any concentration ratio in the step 501;
step 503, enabling laser to enter the standard solution, wherein the standard solution is excited by the laser to generate an optical signal;
step 504, receiving the optical signal generated in the step 503 by a spectrometer, converting the optical signal into an electrical signal, and further converting the electrical signal into a digital signal;
505, receiving a digital signal transmitted by the spectrometer through a data processing system to form a spectrum curve;
step 506, calculating the relative integral fluorescence intensity I according to the information in the spectral curve T Wherein, in the step (A),
Figure FDA0003891108140000021
in the formula, λ 1 Is the starting position wavelength, lambda, of the fluorescence spectrum 2 Is the wavelength of the end position of the fluorescence spectrum, I λ represents the fluorescence intensity at the wavelength λ, I r Representing the light intensity of the Raman peak after deducting the fluorescence background;
step 507, detecting the COD value of the standard solution by adopting a national standard method and the I value obtained in the step 506 T The values form a set of data;
step (ii) of508. Diluting the standard solution in the step 502 at least once, repeating the operation of the steps 503 to 507 for the standard solution diluted each time, and obtaining a plurality of groups of relative integral fluorescence intensity I T Value and COD value;
509, several groups of acquired relative integral fluorescence intensity I T Substituting the value and COD value into the formula COD = KI T And + C, calculating values of K and C by a least square method.
CN202211259745.0A 2022-10-14 2022-10-14 Water quality chemical oxygen demand detection method based on laser spectrum technology Pending CN115615976A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117740748A (en) * 2023-12-20 2024-03-22 湖南省计量检测研究院 BOD online rapid detection method and device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117740748A (en) * 2023-12-20 2024-03-22 湖南省计量检测研究院 BOD online rapid detection method and device

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