Estimation Method of Nitrite Concentration in Environment

Abstract

The present invention provides a method for estimating nitrous acid concentration in an environment, comprising the following steps: S10: obtaining a nitric oxide concentration C1 and a nitrogen dioxide concentration C2, respectively; S20: detecting a nitrous acid concentration C3 in the same period as the nitric oxide concentration C1; S30: calculating a nitrogen oxide concentration generation rate A according to the formula A=C1 / C2; S40: establishing an inverse relationship between the nitrous acid concentration C3 in different time periods and the corresponding nitrogen oxide generation rate A; and S50: obtaining the nitric oxide concentration C1x and the nitrogen dioxide concentration C2x in the time period to be detected, and substituting them into the inverse relationship to calculate the nitrous acid concentration in the time period. The method for estimating nitrous acid concentration in an environment provided by the present invention directly infers the current nitrous acid concentration C3 after measuring the nitric oxide concentration C1 and the nitrogen dioxide concentration C2, thereby reducing monitoring costs.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection, and particularly relates to a method for estimating nitrite concentration in an environment. Background Art

[0002] Hydroxide (OH) and hydroxyl peroxide (HO x ) is an important oxidant in the tropospheric atmosphere, which directly induces atmospheric photochemical processes and plays an important role in the formation of atmospheric pollution. Studies have shown that the contribution of nitrous acid (HONO) to hydroxide (OH) is relatively large compared with other hydroxide (OH) precursors, accounting for up to 60%. In addition, the generation and consumption of nitrous acid (HONO) is also an important part of the atmospheric nitrogen cycle.

[0003] Existing methods for detecting nitrous acid (HONO) in ambient air primarily rely on wet chemistry, which requires the use of strongly acidic chemical reagents. The reagent configuration is hazardous, and operation and maintenance are challenging. Furthermore, the wastewater produced after equipment operation is also hazardous and can cause environmental pollution. Furthermore, the price and maintenance costs of HONO wet chemistry analyzers are high. Summary of the Invention

[0004] The embodiment of the present invention provides a method for estimating nitrite concentration in an environment, aiming to overcome the technical problems of high cost and environmental pollution of nitrite detection.

[0005] To achieve the above object, the technical solution adopted by the present invention is to provide a method for estimating nitrite concentration in an environment, comprising the following steps:

[0006] S10: Obtaining the nitric oxide concentration C1 and the nitrogen dioxide concentration C2 respectively, wherein the nitric oxide concentration C1 and the nitrogen dioxide concentration C2 are in the same period;

[0007] S20: Detecting the nitrous acid concentration C3 at the same time as the nitric oxide concentration C1;

[0008] S30: Calculate the nitrogen oxide concentration generation rate A according to the formula A=C1 / C2;

[0009] S40: establishing an inverse relationship between the nitrous acid concentration C3 at different time periods and the corresponding nitrogen oxide generation rate A;

[0010] S50: Obtain the nitrogen monoxide concentration C1x and the nitrogen dioxide concentration C2x during the detection period, calculate the nitrogen oxide concentration generation rate Ax, and substitute it into the inverse calculation formula to calculate the nitrous acid concentration during the period.

[0011] In a possible implementation, the nitrogen monoxide concentration C1 and the nitrogen dioxide concentration C2 are measured using a nitrogen oxide measuring instrument based on a molybdenum converter conversion-chemiluminescence method.

[0012] In a possible implementation, the nitrous acid concentration C3 is measured using a nitrous acid meter based on a long optical path flow cell absorption spectroscopy technique.

[0013] In a possible implementation, the nitrogen oxide measuring instrument and the nitrite measuring instrument are connected to a computer, and modeling and fitting are performed using MATLAB software or SCILAB software to obtain the inverse calculation formula.

[0014] In a possible implementation, the nitric oxide concentration, the nitrogen dioxide concentration, and the nitrous acid concentration are classified and measured according to weather 1, weather 2, ..., weather n, and steps S10 to S54 are repeated to obtain the inverse calculation formulas corresponding to weather 1, weather 2, ..., weather n, respectively.

[0015] In a possible implementation, the step S10 includes the following steps:

[0016] S11: Select a preset time period;

[0017] S12: measuring the nitric oxide concentration C1 at every preset time interval to obtain C11, C12, C13, ..., C1n in sequence;

[0018] S13: C1=(C11+C12+C13+…+C1n) / n;

[0019] S14: measuring the nitrogen dioxide concentration C2 at every preset time interval to obtain C21, C22, C23, ..., C2n in sequence;

[0020] S15: The C2=(C21+C22+C23+…+C2n) / n.

[0021] In a possible implementation, the nitric oxide concentration C11 further includes d initial nitric oxide concentrations C1;

[0022] The nitrogen dioxide concentration C12 also includes d initial detection nitrogen dioxide concentrations C2.

[0023] In a possible implementation, S20 includes the following steps:

[0024] S21: selecting a time period having the same concentration as the nitric oxide concentration C1;

[0025] S22: measuring the nitrous acid concentration C3 at every preset time interval to obtain C31, C32, C33, ..., C3n in sequence;

[0026] S23: The C3=(C31+C32+C33+…+C3n) / n.

[0027] In a possible implementation, the length of the preset time period is less than or equal to 5 minutes.

[0028] In a possible implementation, the preset time interval is 3 to 5 seconds.

[0029] In the embodiments of the present application, compared to the prior art, the existing monitoring stations are equipped with nitrogen oxide analyzers with a wider coverage. The nitrogen oxide analyzers are used to measure nitrogen oxides, namely, to measure the concentration of nitric oxide C1 and the concentration of nitrogen dioxide C2 respectively, and the nitrogen oxide generation rate A is obtained by calculating the ratio of nitrogen oxides. By using a set of nitrous acid analyzers to measure the concentration of nitrous acid, an inverse calculation relationship between the nitrous acid concentration C3 and the nitrogen oxide generation rate A is established. Subsequently, other monitoring stations can use this inverse calculation relationship to directly infer the current nitrous acid concentration C3 after measuring the concentration of nitric oxide C1 and the concentration of nitrogen dioxide C2. The method for estimating nitrous acid concentration in the environment of the present invention directly infers the current nitrous acid concentration C3 after measuring the concentration of nitric oxide C1 and the concentration of nitrogen dioxide C2, reducing the use of nitrous acid concentration analyzers at each monitoring station and reducing monitoring costs. In addition, the nitrous acid concentration C3 is directly inferred from the inverse calculation relationship and is only used when establishing the inverse calculation relationship, reducing environmental pollution caused by the long-term use of nitrous acid analyzers. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail in the following examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] The method for estimating the nitrous acid concentration in an environment provided by the present invention is now described. The method for estimating the nitrous acid concentration in an environment comprises the following steps:

[0032] S10: Obtaining the nitric oxide concentration C1 and the nitrogen dioxide concentration C2 respectively, wherein the nitric oxide concentration C1 and the nitrogen dioxide concentration C2 are in the same period;

[0033] S20: Detecting the nitrous acid concentration C3 at the same time as the nitric oxide concentration C1;

[0034] S30: Calculate the nitrogen oxide concentration generation rate A according to the formula A=C1 / C2;

[0035] S40: establishing an inverse relationship between the nitrous acid concentration C3 at different time periods and the corresponding nitrogen oxide generation rate A;

[0036] S50: Obtain the nitrogen monoxide concentration C1x and the nitrogen dioxide concentration C2x during the detection period, calculate the nitrogen oxide concentration generation rate Ax, and substitute it into the inverse calculation formula to calculate the nitrous acid concentration during the period.

[0037] The method for estimating nitrous acid concentration in the environment provided by this embodiment is compared with the existing technology. The existing monitoring stations are equipped with nitrogen oxide analyzers with a wider coverage. The nitrogen oxide analyzers are used to measure nitrogen oxides, that is, the nitrogen monoxide concentration C1 and the nitrogen dioxide concentration C2 are measured respectively, and the nitrogen oxide generation rate A is obtained by calculating the ratio of nitrogen oxides. By using a set of nitrous acid analyzers to measure the concentration of nitrous acid, an inverse calculation relationship between the nitrous acid concentration C3 and the nitrogen oxide generation rate A is established. Subsequently, other monitoring stations can use this inverse calculation relationship to directly infer the current nitrous acid concentration C3 after measuring the nitric oxide concentration C1 and the nitrogen dioxide concentration C2. The method for estimating nitrous acid concentration in the environment of the present invention directly infers the current nitrous acid concentration C3 after measuring the nitric oxide concentration C1 and the nitrogen dioxide concentration C2, reducing the use of nitrous acid concentration analyzers at each monitoring station and reducing monitoring costs. In addition, the nitrous acid concentration C3 is directly inferred by the inverse calculation relationship and is only used when establishing the inverse calculation relationship, reducing environmental pollution caused by the long-term use of nitrous acid analyzers.

[0038] In some embodiments, a nitrogen oxide meter based on molybdenum converter conversion-chemiluminescence method is used to measure nitric oxide concentration C1 and nitrogen dioxide concentration C2. This device can simultaneously detect nitric oxide concentration C1 and nitrogen dioxide concentration C2, eliminating the need for two separate devices for detecting nitric oxide and nitrogen dioxide, thus reducing operating costs. Simultaneous measurement also ensures that each batch of nitric oxide concentration C1 and nitrogen dioxide concentration C2 values corresponds to the same time period, improving the accuracy of subsequent calculations.

[0039] In some embodiments, a nitrite concentration C3 is measured using a nitrite meter based on long-pathlength flow cell absorption spectroscopy. The instrument's operating principle is as follows: After nitrite gas is absorbed by an absorption liquid, the sulfonamide and acid in the absorption liquid react to form a diazonium salt, which then combines with naphthylethylenediamine hydrochloride in the developer solution to form a stable pink azo dye. While the meter utilizes an absorption liquid, it is only used during the initial development of the inverse equation. The inverse equation is then used to infer the nitrite concentration C3, avoiding long-term use and reducing environmental pollution caused by the preparation or disposal of the absorption liquid.

[0040] In some embodiments, the nitrogen oxide meter and the nitrite meter are connected to a computer and modeled and fitted using MATLAB or SCILAB software to obtain an inverse calculation relationship. By inputting lattice information into the modeling software, the modeling software can automatically generate a linear relationship curve. For example, if both the nitrogen oxide meter and the nitrite meter are connected to the computer, the data measured by the nitrogen oxide meter will automatically calculate the nitrogen oxide generation rate A in the computer. The nitrogen oxide generation rate A and the nitrite concentration C3 in the same period are then formed into lattice information (A1, C31), (A2, C32), ..., (An, C3n) in the computer, and the inverse calculation relationship can be automatically generated.

[0041] It should be noted that the inverse calculation formula is: C3 = a1*A+b1.

[0042] For example, when using MATLAB, the function curve relationship diagram between the nitrous acid concentration C3 and the nitrogen oxide generation rate A is mainly drawn through it. When the actual measurement is performed later, the nitrogen oxide generation rate A is calculated based on the measured nitric oxide concentration C1 and nitrogen dioxide concentration C2. The nitrogen oxide generation rate A is substituted into the function curve relationship diagram to directly obtain the nitrous acid concentration C3, thereby reducing labor intensity. In addition, the curve relationship diagram drawn by MATLAB software or SCILAB software is more accurate, thereby improving the measurement accuracy of the nitrous acid concentration C3.

[0043] In some embodiments, the concentrations of nitric oxide, nitrogen dioxide, and nitrous acid are measured according to weather 1, weather 2, ..., weather n, and steps S10 to S54 are repeated to obtain inverse calculation equations corresponding to weather 1, weather 2, ..., and weather n, respectively. Depending on the specific weather when constructing the inverse calculation equation, inverse calculation equations can be constructed for different weather conditions, such as sunny, cloudy, and rainy weather conditions, or different inverse calculation equations can be obtained based on different classifications such as temperature, humidity, and precipitation. According to different weather conditions, the corresponding inverse calculation equation is selected according to the weather at the time of actual measurement, which is beneficial to the accuracy of the measurement of nitrous acid concentration C3 in different weather conditions. In addition, for different weather conditions in the same area, the nitrous acid concentration C3 can also be estimated based on different inverse calculation equations.

[0044] In some embodiments, step S10 includes the following steps:

[0045] S11: Select a preset time period;

[0046] S12: measuring the nitric oxide concentration C1 at every preset time interval to obtain C11, C12, C13, ..., C1n in sequence;

[0047] S13: C1=(C11+C12+C13+……+C1n) / n;

[0048] S14: measuring the nitrogen dioxide concentration C2 at every preset time interval to obtain C21, C22, C23, ..., C2n in sequence;

[0049] S15: C2=(C21+C22+C23+……+C2n) / n.

[0050] That is, the nitric oxide concentration C1 is the average value calculated from multiple data points, and the corresponding nitric oxide concentration for that period is calculated using this average value. The nitrogen dioxide concentration C2 is the average value calculated from multiple data points, and the corresponding nitrogen dioxide concentration for that period is calculated using this average value. This process not only reduces the initial computational workload but also ensures data accuracy.

[0051] In some embodiments, the nitric oxide concentration C11 is preceded by d initial detection nitric oxide concentrations C1, and the nitrogen dioxide concentration C12 is preceded by d initial detection nitrogen dioxide concentrations C2, where d is an integer greater than 0.

[0052] The initial d values of the nitric oxide concentration C1 measurement are discarded when the average value is finally calculated, which can avoid errors in the initial measurement when the nitrogen oxide meter is turned on, and thus realize the data correction of the nitric oxide concentration C1 measurement value. Similarly, the d values before the nitrogen dioxide concentration C2 are also discarded, which improves the accuracy of the inverse calculation relationship and thus improves the accuracy of the subsequent reverse calculation of nitrous acid concentration.

[0053] In some embodiments, S20 includes the following steps:

[0054] S21: Select the same time period as the nitric oxide concentration C1;

[0055] S22: measuring the nitrous acid concentration C3 at every preset time interval to obtain C31, C32, C33, ..., C3n in sequence;

[0056] S23: C3=(C31+C32+C33+……+C3n) / n.

[0057] That is, the nitrite concentration C3 is the average value calculated from multiple data points, and the nitrite concentration C3 corresponding to the time period is calculated based on the average value of multiple data points. This process not only reduces the initial calculation workload but also ensures data accuracy.

[0058] In some embodiments, the length of the preset time period is less than or equal to 5 minutes.

[0059] Here we take the preset time period as 5 minutes as an example:

[0060] (1) Measurements were taken from 9:00 to 12:00 in the morning. C11, C12, C13, ..., C1n were measured from 9:00 to 9:05, and then the nitric oxide concentration C1 corresponding to 9:00-9:05 was calculated. Similarly, the nitric oxide concentration C1 corresponding to 9:05-9:10, 9:10-9:15, ..., 11:55-12:00 was obtained.

[0061] (2) C21, C22, C23, ..., C2n were measured from 9:00 to 9:05, and then the nitrogen dioxide concentration C2 corresponding to 9:00-9:05 was calculated; and so on, the nitrogen dioxide concentration C2 corresponding to 9:05-9:10, 9:10-9:15, ..., 11:55-12:00 was obtained respectively.

[0062] (3) The nitrogen monoxide concentration C1 and nitrogen dioxide concentration C2 corresponding to the time period of 9:00-9:05 are calculated to obtain the nitrogen oxide generation rate A; and so on, the nitrogen oxide concentration A corresponding to 9:05-9:10, 9:10-9:15, ..., 11:55-12:00 is obtained respectively.

[0063] (4) C31, C32, C33, ..., C3n were measured from 9:00 to 9:05, and then the corresponding nitrite concentration C3 from 9:00 to 9:05 was calculated. Similarly, the corresponding nitrite concentrations C3 from 9:05 to 9:10, 9:10 to 9:15, ..., and 11:55 to 12:00 were obtained.

[0064] (5) The nitrous acid concentration C3 and the nitrogen oxide generation rate A in the same period constitute a point information in the plane coordinate. Similarly, the point information of different time periods is input into the computer, and the inverse calculation relationship is finally obtained.

[0065] In some embodiments, the preset time interval is 3 to 5 seconds.

[0066] Here we take the preset period as 5 minutes and the preset time interval as 5 seconds as an example:

[0067] The measurement was performed from 9:00 to 12:00 in the morning, and every 5 seconds from 9:00 to 9:05, for a total of 60 nitric oxide concentrations C1. The average of the 60 nitric oxide concentrations C1 was taken to obtain the nitric oxide concentration C1 corresponding to 9:00-9:05. Similarly, the nitric oxide concentrations C1 corresponding to 9:05-9:10, 9:10-9:15, ..., and 11:55-12:00 were obtained respectively.

[0068] The above is a method for calculating the concentration of nitric oxide C1, wherein the calculation of the concentration of nitrogen dioxide C2 and the concentration of nitrous acid C3 is similar.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for estimating nitrite concentration in an environment, characterized in that: The steps include: S10: Obtaining the nitric oxide concentration C1 and the nitrogen dioxide concentration C2 respectively, wherein the nitric oxide concentration C1 and the nitrogen dioxide concentration C2 are in the same period; S20: Detecting the nitrous acid concentration C3 at the same time as the nitric oxide concentration C1; S30: Calculate the nitrogen oxide concentration generation rate A according to the formula A=C1 / C2; S40: establishing an inverse relationship between the nitrous acid concentration C3 at different time periods and the corresponding nitrogen oxide generation rate A; S50: Obtain the nitrogen monoxide concentration C1x and the nitrogen dioxide concentration C2x during the detection period, calculate the nitrogen oxide concentration generation rate Ax, and substitute it into the inverse calculation formula to calculate the nitrous acid concentration during the period.

2. The method for estimating nitrous acid concentration in an environment as claimed in claim 1, wherein The nitrogen monoxide concentration C1 and the nitrogen dioxide concentration C2 are measured using a nitrogen oxide measuring instrument based on a molybdenum converter conversion-chemiluminescence method.

3. The method for estimating nitrous acid concentration in an environment as claimed in claim 2, wherein: The nitrous acid concentration C3 is measured using a nitrous acid measuring instrument based on a long optical path flow cell absorption spectroscopy technique.

4. The method for estimating nitrous acid concentration in an environment as claimed in claim 3, wherein: The nitrogen oxide measuring instrument and the nitrite measuring instrument are connected to a computer, and modeling and fitting are performed using MATLAB software or SCILAB software to obtain the inverse calculation formula.

5. The method for estimating nitrous acid concentration in an environment as claimed in claim 1, wherein: The nitric oxide concentration, the nitrogen dioxide concentration and the nitrous acid concentration are measured according to weather 1, weather 2, ..., weather n, and the steps S10 to S54 are repeated to obtain the inverse calculation formulas corresponding to weather 1, weather 2, ..., weather n respectively.

6. The method for estimating nitrous acid concentration in an environment as claimed in claim 1, wherein: The step S10 includes the following steps: S11: Select a preset time period; S12: measuring the nitric oxide concentration C1 at every preset time interval to obtain C11, C12, C13, ..., C1n in sequence; S13: C1=(C11+C12+C13+…+C1n) / n; S14: measuring the nitrogen dioxide concentration C2 at every preset time interval to obtain C21, C22, C23, ..., C2n in sequence; S15: The C2=(C21+C22+C23+…+C2n) / n.

7. The method for estimating nitrous acid concentration in an environment as claimed in claim 6, wherein: The nitric oxide concentration C11 also includes d initial nitric oxide concentrations C1; The nitrogen dioxide concentration C12 also includes d initial detection nitrogen dioxide concentrations C2.

8. The method for estimating nitrous acid concentration in an environment as claimed in claim 6 or 7, wherein: The S20 includes the following steps: S21: selecting a time period having the same concentration as the nitric oxide concentration C1; S22: measuring the nitrous acid concentration C3 at every preset time interval to obtain C31, C32, C33, ..., C3n in sequence; S23: The C3=(C31+C32+C33+…+C3n) / n.

9. The method for estimating nitrous acid concentration in an environment as claimed in claim 8, wherein: The length of the preset time period is less than or equal to 5 minutes.

10. The method for estimating nitrous acid concentration in an environment as claimed in claim 8, wherein: The preset time interval is 3 to 5 seconds.