1. The method of the water sample high-precision COD detection device is used for improving the detection precision of the miniature COD detection device and is characterized in that: the absorbance detection and correction method in the method specifically comprises the steps of firstly preparing calibration solutions with various concentrations, then measuring to obtain a calibration data set of the COD absorbance of the calibration solutions changing along with the temperature within the temperature range required by the COD detection, carding to obtain the absorbance changing along with the temperature curves of the high-concentration calibration solutions and the low-concentration calibration solutions, fitting the two curves to obtain temperature compensation curve formulas of the high-concentration COD water sample and the low-concentration COD water sample, and correcting the measured original absorbance data by using the temperature compensation curve formula during the water sample detection of the micro COD detection device.

2. The method of the water sample high precision COD detecting device according to claim 1, characterized in that: the temperature range of COD detection of the micro COD detection device is 0-45 ℃;

when measuring the data of the absorbance of the calibration solution changing along with the temperature, the temperature of the calibration solution is changed and stabilized, and the absorbance of the calibration solution under the illumination environment with the wavelength of 254nm is measured by a probe sensor of the micro COD detection device.

3. The method of the water sample high precision COD detecting device according to claim 2, characterized in that: the micro COD detection device calculates the absorbance of a calibration solution or a water sample through the ad0 value of a COD wave band and the ad1 value of a turbidity wave band which are acquired by a probe sensor; when the probe sensor is placed in distilled water in a zero setting mode, the micro COD detection device records the current ad0 (zero) value of the COD wave band and the ad1 (zero) value of the turbidity wave band through software; when the probe sensor measures the absorbance of the calibration solution or water sample, the probe sensor is placed in the liquid, the micro COD detection device records the current COD waveband ad0(sample) value and the current turbidity waveband ad1 (sample) value through software, and then the original absorbance data of the current calibration solution or water sample is calculated according to an absorbance calculation formula, wherein the absorbance calculation formula is

log10 (ad 0 (zero)/ad 0 (sample)) -log 10 (ad 0 (zero)/ad 0 (sample)) formula a.

4. The method of the water sample high precision COD detecting device according to claim 3, characterized in that: the calibration solution is a potassium hydrogen phthalate standard solution, the concentration of the high-concentration calibration solution is more than 100mg/L, and the concentration of the low-concentration calibration solution is less than 100 mg/L;

the temperature compensation curve formulas of the high-concentration COD water sample and the low-concentration COD water sample are respectively

y = f1(x) 0 ≦ x ≦ 45 formula one;

y = f2(x) 0 ≦ x ≦ 45 formula two;

wherein y represents absorbance and x represents temperature;

after the micro COD detection device calculates the original absorbance of the liquid to be detected according to an absorbance calculation formula, determining the concentration of the liquid according to the original absorbance, and determining whether a formula I or a formula II is adopted to correct the original absorbance data according to a determination result; the specific method comprises the following steps:

a) if the original absorbance A measured by the current software is in the range [0,0.4], respectively calculating the absorbance B at the current temperature and the absorbance C at 25 ℃ by combining the current temperature and adopting a formula I, and then obtaining the absorbance D after temperature compensation by using a temperature compensation algorithm D ═ A + (C-B);

b) if the original absorbance A measured by the current software is in the range (0.4,1.1], respectively calculating the absorbance B at the current temperature and the absorbance C at 25 ℃ by adopting a formula II according to the current temperature, and then obtaining the absorbance D after temperature compensation by using a temperature compensation algorithm D ═ A + (C-B).

5. The method of the water sample high precision COD detecting device according to claim 4, characterized in that: the liquid concentration calibration method in the method comprises the steps that a micro COD detection device respectively measures the original absorbance of a plurality of calibration solutions with different concentrations, then the data are corrected by a temperature compensation curve formula to obtain absorbance data, and then a Lagrangian algorithm is utilized to obtain a concentration formula

Y = = f (x) formula three,

x represents absorbance data, and Y represents the concentration of the calibration solution;

the liquid concentration measuring method in the method comprises the steps of measuring absorbance data of the liquid to be measured after being corrected by a temperature compensation curve formula by the micro COD detection device, and substituting the absorbance data into a formula III to obtain the concentration of the liquid to be measured.

6. The method of the water sample high precision COD detecting device according to claim 4, characterized in that: the calibration solution is potassium hydrogen phthalate standard solution with COD values of 50mg/L, 100mg/L, 150mg/L and 300mg/L, the temperature of the calibration solution is changed by a water bath box in the process of measuring a calibration data set with the absorbance of the calibration solution changing along with the temperature, and each calibration solution is kept at the same temperature to respectively measure the absorbance of the calibration solution at the light wavelength of 254 nm.

7. Water sample high accuracy COD detection device, its characterized in that: a small detection groove for leading in a water sample to be detected is arranged in a water sample detection light path of the COD detection device; a cleaning brush is arranged in the detection groove; the cleaning brush wipes the optical path component in the detection tank to reduce the interference of impurities on the optical path; the cleaning brush is driven by a motor, and a control circuit of the motor takes the variation fluctuation of the motor current larger than a threshold value as a cleaning brush reversing signal.

8. The water sample high precision COD detection device of claim 7, characterized in that: the control circuit of the motor comprises a microprocessor; the detection groove limits the moving path of the cleaning brush by the groove wall, when the cleaning brush moves to one end part of the detection groove and is blocked by the groove wall, the resistance of the motor rises to increase the current of the motor to form a cleaning brush reversing signal which can be identified by the microprocessor, and after the microprocessor receives the end part positioning signal, the motor is controlled to drive the cleaning brush to reversely move to the other end part of the detection groove.

9. The water sample high precision COD detection device of claim 8, characterized in that: the detection groove is an arc-shaped groove, and the light path component in the detection groove is an optical detection window arranged at the groove wall; the motor drives the cleaning brush to swing left and right in the detection groove in a reciprocating mode so as to wipe the optical detection window; the microprocessor control circuit of the motor comprises a current conversion voltage circuit; when the swinging of the cleaning brush is blocked by the groove wall to cause the resistance of the motor to rise so as to increase the current of the motor, the current conversion voltage circuit converts the current fluctuation information into a high level signal which can be recognized by the microprocessor and transmits the high level signal to the microprocessor as a cleaning brush reversing signal.

10. The water sample high precision COD detection device of claim 9, characterized in that: the optical window is in a boss shape at the groove wall, and when the cleaning brush is used for wiping the optical window, the soft elastic component is contacted with the optical window so as to avoid the phenomenon that the motor resistance is too large to form a cleaning brush reversing signal;

the COD detection device also comprises a single chip microcomputer, and the single chip microcomputer corrects the measured original absorbance data according to a temperature compensation curve formula.

Background

When water sample is detected, ultraviolet rays are often adopted for optical detection, but the temperature can influence the absorbance of the solution to the ultraviolet rays, so that the measured value is influenced. Because the temperature affects the chemical reaction of the solution and the movement of molecules, some chemical reactions do not occur at normal temperature, but the reaction is possible when the temperature is high; and the temperature can affect the energy of electrons at the outer layer of atoms, so that the absorption spectrum is changed, the absorption spectrum is shifted, and temperature compensation is needed.

Simultaneously COD detection device commonly used in the market at present, its solution to the cleaning brush location uses the opto-coupler to detect the location, but this kind of method is with high costs, and the structure need set up installation opto-coupler position, and the error rate is high and to the technology equipment requirement higher, does not design well to miniaturized product structure, does not have sufficient space to lay the opto-coupler moreover often.

Disclosure of Invention

The invention provides a water sample high-precision COD detection device and a water sample high-precision COD detection method, which adopt a software-based temperature compensation scheme to correct water sample COD detection data, so that the detection device can be miniaturized on the premise of ensuring the detection precision, and meanwhile, a miniaturized cleaning device is also arranged at a detection light path of the product, so that the influence of light path dirt on the detection precision can be reduced.

The invention adopts the following technical scheme.

A method for a high-precision COD detection device of a water sample is used for improving the detection precision of the micro COD detection device, and the absorbance detection and correction method in the method specifically comprises the steps of firstly preparing calibration solutions with various concentrations, then measuring to obtain a calibration data set of the COD absorbance of the calibration solutions changing along with the temperature within the temperature range required by the COD detection, carding to obtain the COD absorbance changing along with the temperature curves of the high-concentration calibration solutions and the low-concentration calibration solutions, fitting the two curves to obtain temperature compensation curve formulas of the high-concentration COD water sample and the low-concentration COD water sample, and correcting the measured original absorbance data by using the temperature compensation curve formula when the water sample of the micro COD detection device is detected.

The temperature range of COD detection of the micro COD detection device is 0-45 ℃;

when measuring the data of the absorbance of the calibration solution changing along with the temperature, the temperature of the calibration solution is changed and stabilized, and the absorbance of the calibration solution under the illumination environment with the wavelength of 254nm is measured by a probe sensor of the micro COD detection device.

The micro COD detection device calculates the absorbance of a calibration solution or a water sample through the ad0 value of a COD wave band and the ad1 value of a turbidity wave band which are acquired by a probe sensor; when the probe sensor is placed in distilled water in a zero setting mode, the micro COD detection device records the current ad0 (zero) value of the COD wave band and the ad1 (zero) value of the turbidity wave band through software; when the probe sensor measures the absorbance of the calibration solution or water sample, the probe sensor is placed in the liquid, the micro COD detection device records the current COD waveband ad0(sample) value and the current turbidity waveband ad1 (sample) value through software, and then the original absorbance data of the current calibration solution or water sample is calculated according to an absorbance calculation formula, wherein the absorbance calculation formula is

log10 (ad 0 (zero)/ad 0 (sample)) -log 10 (ad 0 (zero)/ad 0 (sample)) formula a.

The calibration solution is a potassium hydrogen phthalate standard solution, the concentration of the high-concentration calibration solution is more than 100mg/L, and the concentration of the low-concentration calibration solution is less than 100 mg/L;

the temperature compensation curve formulas of the high-concentration COD water sample and the low-concentration COD water sample are respectively

y = f1(x) 0 ≦ x ≦ 45 formula one;

y = f2(x) 0 ≦ x ≦ 45 formula two;

wherein y represents absorbance and x represents temperature;

after the micro COD detection device calculates the original absorbance of the liquid to be detected according to an absorbance calculation formula, determining the concentration of the liquid according to the original absorbance, and determining whether a formula I or a formula II is adopted to correct the original absorbance data according to a determination result; the specific method comprises the following steps:

a) if the original absorbance A measured by the current software is in the range [0,0.4], respectively calculating the absorbance B at the current temperature and the absorbance C at 25 ℃ by combining the current temperature and adopting a formula I, and then obtaining the absorbance D after temperature compensation by using a temperature compensation algorithm D ═ A + (C-B);

b) if the original absorbance A measured by the current software is in the range (0.4,1.1], respectively calculating the absorbance B at the current temperature and the absorbance C at 25 ℃ by adopting a formula II according to the current temperature, and then obtaining the absorbance D after temperature compensation by using a temperature compensation algorithm D ═ A + (C-B).

The liquid concentration calibration method in the method comprises the steps that a micro COD detection device respectively measures the original absorbance of a plurality of calibration solutions with different concentrations, then the data are corrected by a temperature compensation curve formula to obtain absorbance data, and then a Lagrangian algorithm is utilized to obtain a concentration formula

Y = = f (x) formula three,

x represents absorbance data, and Y represents the concentration of the calibration solution;

the liquid concentration measuring method in the method comprises the steps of measuring absorbance data of the liquid to be measured after being corrected by a temperature compensation curve formula by the micro COD detection device, and substituting the absorbance data into a formula III to obtain the concentration of the liquid to be measured.

The calibration solution is potassium hydrogen phthalate standard solution with COD values of 50mg/L, 100mg/L, 150mg/L and 300mg/L, the temperature of the calibration solution is changed by a water bath box in the process of measuring a calibration data set with the absorbance of the calibration solution changing along with the temperature, and each calibration solution is kept at the same temperature to respectively measure the absorbance of the calibration solution at the light wavelength of 254 nm.

The water sample high-precision COD detection device is characterized in that a small detection groove for leading in a water sample to be detected is arranged in a water sample detection light path of the COD detection device; a cleaning brush is arranged in the detection groove; the cleaning brush wipes the optical path component in the detection tank to reduce the interference of impurities on the optical path; the cleaning brush is driven by a motor, and a control circuit of the motor takes the variation fluctuation of the motor current larger than a threshold value as a cleaning brush reversing signal.

The control circuit of the motor comprises a microprocessor; the detection groove limits the moving path of the cleaning brush by the groove wall, when the cleaning brush moves to one end part of the detection groove and is blocked by the groove wall, the resistance of the motor rises to increase the current of the motor to form a cleaning brush reversing signal which can be identified by the microprocessor, and after the microprocessor receives the end part positioning signal, the motor is controlled to drive the cleaning brush to reversely move to the other end part of the detection groove.

The detection groove is an arc-shaped groove, and the light path component in the detection groove is an optical detection window arranged at the groove wall; the motor drives the cleaning brush to swing left and right in the detection groove in a reciprocating mode so as to wipe the optical detection window; the microprocessor control circuit of the motor comprises a current conversion voltage circuit; when the swinging of the cleaning brush is blocked by the groove wall to cause the resistance of the motor to rise so as to increase the current of the motor, the current conversion voltage circuit converts the current fluctuation information into a high level signal which can be recognized by the microprocessor and transmits the high level signal to the microprocessor as a cleaning brush reversing signal.

The optical window is in a boss shape at the groove wall, and when the cleaning brush is used for wiping the optical window, the soft elastic component is contacted with the optical window so as to avoid the phenomenon that the motor resistance is too large to form a cleaning brush reversing signal;

the COD detection device also comprises a single chip microcomputer, and the single chip microcomputer corrects the measured original absorbance data according to a temperature compensation curve formula.

The temperature compensation scheme provided by the invention considers the common detection environment temperature range and the optical characteristics of water samples under different concentrations, adopts a data calibration mode to form a temperature compensation curve and fits a compensation formula with high and low concentrations, has ideal actual measurement effect, and can effectively improve the COD detection precision.

The cleaning brush positioning scheme of the invention is to fix the initial rotation direction of the hanging brush (cleaning brush) to rotate leftwards or rightwards. When the motor contacts the structural wall, the resistance of the motor is increased, the current is taken out and sent to the CPU by using a current conversion voltage circuit, and the CPU detects a high level which indicates that the motor is turned to a positioning point. The motor is then controlled to rotate in the opposite direction and hit another structure wall, and the voltage level converted from the current is detected. By the design, the electrical characteristics of the motor are fully utilized, other positioning parts are not needed, the cost is saved, the motor can be effectively prevented from being burnt by sundries in the process of detecting the high-dirty water environment, and the water quality adaptability of the COD detection device can be improved.

Drawings

The invention is described in further detail below with reference to the following figures and detailed description:

FIG. 1 is a diagram showing the change curve of COD absorbance of a 50mg/L calibration solution with temperature;

FIG. 2 is a diagram showing the change curve of COD absorbance of a calibration solution of 100mg/L with temperature;

FIG. 3 is a diagram showing the curve of COD absorbance of a calibration solution at 150mg/L as a function of temperature;

FIG. 4 is a graph showing the change of COD absorbance of a calibration solution at 300mg/L with temperature;

FIG. 5 is a schematic diagram of a single-chip microcomputer circuit in the present invention;

FIG. 6 is a schematic diagram of a control circuit for the cleaning brush motor of the present invention;

FIG. 7 is another schematic diagram of the control circuit for the cleaning brush motor of the present invention;

FIG. 8 is a schematic view of the cleaning brush of the COD detecting device of the present invention;

in the figure: 1-a motor; 2-one end of the detection tank; 3-the other end of the detection cell; 4-a cleaning brush; 5-an optical detection window; 6-detection tank.

Detailed Description

As shown in the figure, the method of the water sample high-precision COD detection device is used for improving the detection precision of the micro COD detection device, and the absorbance detection correction method in the method specifically comprises the steps of firstly preparing calibration solutions with various concentrations, then measuring to obtain a calibration data set of the COD absorbance of the calibration solutions changing along with the temperature within the temperature range required by the COD detection, carding to obtain the COD absorbance changing curves of the high-concentration calibration solutions and the low-concentration calibration solutions along with the temperature, fitting the two curves to obtain the temperature compensation curve formulas of the high-concentration COD water sample and the low-concentration COD water sample, and correcting the measured original absorbance data by using the temperature compensation curve formula when the water sample of the micro COD detection device is detected.

The temperature range of COD detection of the micro COD detection device is 0-45 ℃;

when measuring the data of the absorbance of the calibration solution changing along with the temperature, the temperature of the calibration solution is changed and stabilized, and the absorbance of the calibration solution under the illumination environment with the wavelength of 254nm is measured by a probe sensor of the micro COD detection device.

The micro COD detection device calculates the absorbance of a calibration solution or a water sample through the ad0 value of a COD wave band and the ad1 value of a turbidity wave band which are acquired by a probe sensor; when the probe sensor is placed in distilled water in a zero setting mode, the micro COD detection device records the current ad0 (zero) value of the COD wave band and the ad1 (zero) value of the turbidity wave band through software; when the probe sensor measures the absorbance of the calibration solution or water sample, the probe sensor is placed in the liquid, the micro COD detection device records the current COD waveband ad0(sample) value and the current turbidity waveband ad1 (sample) value through software, and then the original absorbance data of the current calibration solution or water sample is calculated according to an absorbance calculation formula, wherein the absorbance calculation formula is

log10 (ad 0 (zero)/ad 0 (sample)) -log 10 (ad 0 (zero)/ad 0 (sample)) formula a.

The calibration solution is a potassium hydrogen phthalate standard solution, the concentration of the high-concentration calibration solution is more than 100mg/L, and the concentration of the low-concentration calibration solution is less than 100 mg/L;

the temperature compensation curve formulas of the high-concentration COD water sample and the low-concentration COD water sample are respectively

y = f1(x) 0 ≦ x ≦ 45 formula one;

y = f2(x) 0 ≦ x ≦ 45 formula two;

wherein y represents absorbance and x represents temperature;

after the micro COD detection device calculates the original absorbance of the liquid to be detected according to an absorbance calculation formula, determining the concentration of the liquid according to the original absorbance, and determining whether a formula I or a formula II is adopted to correct the original absorbance data according to a determination result; the specific method comprises the following steps:

a) if the original absorbance A measured by the current software is in the range [0,0.4], respectively calculating the absorbance B at the current temperature and the absorbance C at 25 ℃ by combining the current temperature and adopting a formula I, and then obtaining the absorbance D after temperature compensation by using a temperature compensation algorithm D ═ A + (C-B);

b) if the original absorbance A measured by the current software is in the range (0.4,1.1], respectively calculating the absorbance B at the current temperature and the absorbance C at 25 ℃ by adopting a formula II according to the current temperature, and then obtaining the absorbance D after temperature compensation by using a temperature compensation algorithm D ═ A + (C-B).

The liquid concentration calibration method in the method comprises the steps that a micro COD detection device respectively measures the original absorbance of a plurality of calibration solutions with different concentrations, then the data are corrected by a temperature compensation curve formula to obtain absorbance data, and then a Lagrangian algorithm is utilized to obtain a concentration formula

Y = = f (x) formula three,

x represents absorbance data, and Y represents the concentration of the calibration solution;

the liquid concentration measuring method in the method comprises the steps of measuring absorbance data of the liquid to be measured after being corrected by a temperature compensation curve formula by the micro COD detection device, and substituting the absorbance data into a formula III to obtain the concentration of the liquid to be measured.

The calibration solution is potassium hydrogen phthalate standard solution with COD values of 50mg/L, 100mg/L, 150mg/L and 300mg/L, the temperature of the calibration solution is changed by a water bath box in the process of measuring a calibration data set with the absorbance of the calibration solution changing along with the temperature, and each calibration solution is kept at the same temperature to respectively measure the absorbance of the calibration solution at the light wavelength of 254 nm.

The water sample high-precision COD detection device is characterized in that a small detection groove 6 for leading in a water sample to be detected is arranged in a water sample detection light path of the COD detection device; a cleaning brush 4 is arranged in the detection groove; the cleaning brush wipes the optical path component in the detection tank to reduce the interference of impurities on the optical path; the cleaning brush is driven by a motor 1, and a control circuit of the motor takes variation fluctuation of motor current larger than a threshold value as a cleaning brush reversing signal.

The control circuit of the motor comprises a microprocessor; the detection groove limits the moving path of the cleaning brush by the groove wall, when the cleaning brush moves to one end part 2 of the detection groove and is blocked by the groove wall, the resistance of the motor rises to increase the current of the motor to form a cleaning brush reversing signal which can be identified by the microprocessor, and after the microprocessor receives the end part positioning signal, the motor is controlled to drive the cleaning brush to reversely move to the other end part 3 of the detection groove. Until the brush is blocked by the slot wall again, the brush forms a cleaning brush reversing signal again because of the rising of the resistance of the motor.

The detection groove is an arc-shaped groove, and the light path component in the detection groove is an optical detection window 5 arranged at the groove wall; the motor drives the cleaning brush to swing left and right in the detection groove in a reciprocating mode so as to wipe the optical detection window; the microprocessor control circuit of the motor comprises a current conversion voltage circuit; when the swinging of the cleaning brush is blocked by the groove wall to cause the resistance of the motor to rise so as to increase the current of the motor, the current conversion voltage circuit converts the current fluctuation information into a high level signal which can be recognized by the microprocessor and transmits the high level signal to the microprocessor as a cleaning brush reversing signal.

The optical window is in a boss shape at the groove wall, and when the cleaning brush is used for wiping the optical window, the soft elastic component is contacted with the optical window so as to avoid the phenomenon that the motor resistance is too large to form a cleaning brush reversing signal;

the COD detection device also comprises a single chip microcomputer, and the single chip microcomputer corrects the measured original absorbance data according to a temperature compensation curve formula.

In the embodiment, the calibration data set of the measured COD absorbance of the calibration solution changing along with the temperature is filled into excel software to obtain a corresponding absorbance changing along with the temperature, the first formula and the second formula are obtained by fitting specific absorbance changing along with the temperature, and the specific form of the formula can be different along with the component change of the calibration solution and the change of the detection environment temperature range, namely, the water sample high-precision COD detection device can form a temperature compensation algorithm formula suitable for other detection temperatures by changing the component of the calibration solution and measuring the environment temperature of the calibration solution.