阅读说明：本技术 一种监测湿沉降蒸发过程中释放易挥发气体通量的方法 (Method for monitoring flux of volatile gas released in wet sedimentation evaporation process ) 是由 徐莹莹 窦应铂 杨旭 衣妍 赵秋雨 吕姣 刘弘钊 于 2020-12-07 设计创作，主要内容包括：本发明提供了一种监测湿沉降蒸发过程中释放易挥发气体通量的方法,依据酸碱中和原理,当被监测的易挥发气体为碱性气体时,采用酸性溶液润湿并烘干的容器吸收所述气体；当被监测的易挥发气体为酸性气体时,采用碱性溶液润湿并烘干的容器吸收所述气体；控制酸性溶液和碱性溶液的浓度高于0.1mol/L,将需监测的易挥发气体完全吸收在容器中,然后采用不包含易挥发气体的前体离子的溶剂将其溶解后就可以测试出易挥发气体的前体离子的浓度,进而计算出湿沉降易挥发气体通量。(The invention provides a method for monitoring flux of volatile gas released in a wet sedimentation evaporation process, which is characterized in that according to an acid-base neutralization principle, when the volatile gas to be monitored is alkaline gas, a container wetted by an acid solution and dried is adopted to absorb the gas; when the monitored volatile gas is acid gas, absorbing the gas by a container which is wetted by alkaline solution and dried; controlling the concentration of the acid solution and the alkaline solution to be higher than 0.1mol/L, completely absorbing volatile gas to be monitored in a container, dissolving the volatile gas in a solvent which does not contain precursor ions of the volatile gas, testing the concentration of the precursor ions of the volatile gas, and further calculating the flux of wet settlement volatile gas.)

1. A method of monitoring flux of volatile gases released during wet settling evaporation, comprising the steps of:

(1) when the monitored volatile gas is alkaline gas, introducing gas evaporated from the wet sedimentation sample into a container with the inner wall wetted by the acid solution and dried, and performing neutralization reaction to obtain a container for absorbing the gas; when the monitored volatile gas is acidic gas, introducing gas evaporated from the wet sedimentation sample into a container with the inner wall wetted and dried by alkaline solution, and carrying out neutralization reaction to obtain a container for absorbing gas;

(2) adding a solvent into the container for absorbing the gas obtained in the step (1) to dissolve precursor ions in the absorbed gas to obtain a solution;

(3) testing the concentration of precursor ions in the solution obtained in the step (2), and calculating to obtain the flux of volatile gas;

the alkaline solution and the acidic solution in the step (1) and the solvent in the step (2) do not contain precursor ions of volatile gas;

the concentration of the alkaline solution and the concentration of the acidic solution in the step (1) are independently higher than 0.1 mol/L.

2. The method according to claim 1, wherein the wet settled sample in step (1) is rainwater, dew, snow or frost.

3. The method of claim 1, wherein the wet settled sample of step (1) further comprises filtration prior to evaporation.

4. The method according to claim 3, wherein the filter membrane used for the filtration has a pore size of 0.22 or 0.45 μm.

5. The method according to claim 1, wherein the acidic solution in the step (1) is an oxalic acid solution or a citric acid solution.

6. The method according to claim 1, wherein the evaporation of the wet settled sample in step (1) is performed under conditions simulating natural wind speed.

7. The method as claimed in claim 1, wherein the volatile gas in the step (1) is at least one of ammonia gas and gaseous nitrous acid.

8. The method of claim 1, wherein the vessel in step (1) is an annular etcher.

9. The method of claim 1, wherein the solvent in step (2) is deionized water.

10. The method according to claim 1, wherein the concentration of precursor ions of volatile gas in the solution obtained in the step (2) is measured by ion chromatography in the step (3).

Technical Field

The invention belongs to the technical field of monitoring gas release processes, and particularly relates to a method for monitoring flux of volatile gas released in a wet sedimentation evaporation process.

Background

Wet sedimentation is a process in which precipitation forms such as rain and snow in the atmosphere and other forms of water vapor condensate play a role in removing air pollutants, is a commonly-occurring weather phenomenon, and can effectively purify aerosol in the atmosphere, so that the wet sedimentation becomes an effective way for removing pollutants in the near-surface atmosphere. After wet settling occurs, during evaporation near the surface, some of the dissolved or adsorbed contaminants are released and become secondary polluting precursors in the atmosphere. For example, wet settling removes NH from the atmosphere₄ ⁺And NO₂ ^-Will be reacted with NH₃And NH in the form of HONO (gaseous nitrous acid) escaping during evaporation, released into the atmosphere₃And HONO to NH₄ ⁺And OH can exacerbate the haze level. At present, the method for monitoring the diffusion of volatile gas in the atmosphere is mainly a direct monitoring method, namely, an instrument is used for directly monitoring the concentration of the volatile gas in the atmosphere. The monitoring method can only monitor the concentration of volatile gas in the atmosphere, and has no way to monitor the flux of the gas released in the wet sedimentation evaporation process, thereby influencing the treatment of atmospheric pollution. Therefore, in order to effectively treat the atmospheric pollution, the monitoring method needs to be improved to monitor the flux of volatile gas released in the wet sedimentation evaporation process.

Disclosure of Invention

The invention aims to provide a method for monitoring flux of volatile gas released in a wet sedimentation evaporation process. The method provided by the invention can monitor the flux of volatile gas released in the evaporation process of atmospheric wet deposition.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a method for monitoring flux of volatile gas released in a wet sedimentation evaporation process, which comprises the following steps:

(1) when the monitored volatile gas is alkaline gas, introducing gas evaporated from the wet sedimentation sample into a container with the inner wall wetted by the acid solution and dried, and performing neutralization reaction to obtain a container for absorbing the gas; when the monitored volatile gas is acidic gas, introducing gas evaporated from the wet sedimentation sample into a container with the inner wall wetted and dried by alkaline solution, and carrying out neutralization reaction to obtain a container for absorbing gas;

(2) adding a solvent into the container for absorbing the gas obtained in the step (1) to dissolve precursor ions in the absorbed gas to obtain a solution;

(3) testing the concentration of precursor ions in the solution obtained in the step (2), and calculating to obtain the flux of volatile gas;

the alkaline solution and the acidic solution in the step (1) and the solvent in the step (2) do not contain precursor ions of volatile gas;

the concentration of the alkaline solution and the concentration of the acidic solution in the step (1) are independently higher than 0.1 mol/L.

Preferably, the wet settled sample in step (1) is rainwater, dew, snow or frost.

Preferably, the wet settled sample in step (1) further comprises filtration before evaporation.

Preferably, the filter membrane used for the filtration has a pore size of 0.22 or 0.45 μm.

Preferably, the acidic solution in step (1) is an oxalic acid solution or a citric acid solution.

Preferably, the evaporation of the wet settled sample in the step (1) is performed under the condition of simulating the natural wind speed.

Preferably, the volatile gas in the step (1) is at least one of ammonia gas and gaseous nitrous acid.

Preferably, the container in the step (1) is an annular corrosion vessel.

Preferably, the solvent in step (2) is deionized water.

Preferably, the concentration of precursor ions of volatile gas in the solution obtained in the step (2) is tested by ion chromatography in the step (3).

The invention provides a method for monitoring flux of volatile gas released in a wet sedimentation evaporation process, which comprises the following steps: when the monitored volatile gas is alkaline gas, introducing gas evaporated from the wet sedimentation sample into a container with the inner wall wetted by the acid solution and dried, and performing neutralization reaction to obtain a container for absorbing the gas; when the monitored volatile gas is acidic gas, introducing gas evaporated from the wet sedimentation sample into a container with the inner wall wetted and dried by alkaline solution, and carrying out neutralization reaction to obtain a container for absorbing gas; adding a solvent into the container for absorbing the gas to dissolve precursor ions in the absorbed gas to obtain a solution; testing the concentration of precursor ions in the solution, and calculating to obtain the flux of volatile gas; the alkaline and acidic solutions and the solvent do not contain precursor ions of volatile gases; the concentration of the alkaline solution and the acidic solution is independently higher than 0.1 mol/L. According to the method, according to an acid-base neutralization principle, when the monitored volatile gas is alkaline gas, a container which is wetted and dried by an acid solution containing no precursor ions of the volatile gas is adopted to absorb the gas through acid-base neutralization; when the monitored volatile gas is acid gas, a container which is wetted and dried by alkaline solution containing no precursor ions of the volatile gas is used for absorbing the gas through acid-base neutralization; and controlling the concentration of the acid solution and the alkaline solution to be higher than 0.1mol/L, completely absorbing volatile gas to be monitored in a container, dissolving the volatile gas in a solvent which does not contain precursor ions of the volatile gas to test the concentration of the precursor ions of the volatile gas, and further calculating the flux of wet settlement volatile gas. The results of the examples show that the method provided by the invention monitors the release of volatile gas NH in the rainwater₃The flux was 85mg/m²(ii) a The flux of HONO which is released as volatile gas in the snowy water is monitored to be 267.9mg/m²(ii) a Monitoring release of volatile gas NH in dew₃The flux was 1.632mg/m²HONO flux is 6.909mg/m²。

Drawings

FIG. 1 is a schematic diagram of an apparatus for monitoring flux of volatile gas released during wet-settling evaporation in example 3;

in the figure, 1 is an iron stand, 2 is a test tube, 3 and 4 are eroders, 5 is a filtered wet sediment sample, and 6 is a clean air inlet.

Detailed Description

The invention provides a method for monitoring flux of volatile gas released in a wet sedimentation evaporation process, which comprises the following steps:

(1) when the monitored volatile gas is alkaline gas, introducing gas evaporated from the wet sedimentation sample into a container with the inner wall wetted by the acid solution and dried, and performing neutralization reaction to obtain a container for absorbing the gas; when the monitored volatile gas is acidic gas, introducing gas evaporated from the wet sedimentation sample into a container with the inner wall wetted and dried by alkaline solution, and carrying out neutralization reaction to obtain a container for absorbing gas;

(2) adding a solvent into the container for absorbing the gas obtained in the step (1) to dissolve precursor ions in the absorbed gas to obtain a solution;

(3) testing the concentration of precursor ions in the solution obtained in the step (2), and calculating to obtain the flux of volatile gas;

the alkaline solution and the acidic solution in the step (1) and the solvent in the step (2) do not contain precursor ions of volatile gas;

the concentration of the alkaline solution and the concentration of the acidic solution in the step (1) are independently higher than 0.1 mol/L.

The volatile gas is not particularly limited in kind, and is suitable for detection of acid and alkaline gases well known to those skilled in the art. In the present invention, the volatile gas is preferably at least one of ammonia gas and gaseous nitrous acid.

In the present invention, the wet sedimentation sample is preferably rainwater, dew, snow or frost. The sampling operation of the wet settled sample is not particularly limited in the present invention, and a sampling operation known to those skilled in the art may be adopted. In the present invention, when the wet sediment sample is snow, it is preferable to further include subjecting the wet sediment sample to a thawing treatment. The operation of the melting treatment in the present invention is not particularly limited, and may be performed by a method known to those skilled in the art.

In the invention, when the monitored volatile gas is alkaline gas, the gas evaporated from the wet sedimentation sample is introduced into a container the inner wall of which is wetted by an acid solution and dried, and neutralization reaction is carried out to obtain a container for absorbing gas.

In the present invention, the wet settled sample preferably further comprises filtration before being subjected to evaporation; the pore size of the filter membrane used for the filtration is preferably 0.22 or 0.45. mu.m. The source of the filter membrane is not particularly limited in the present invention, and a filter membrane known to those skilled in the art may be used. In the present invention, the wet sediment sample is filtered to remove particulate matter from the wet sediment sample in order to avoid calculation of the volatile gas flux that includes a portion of the particulate matter conversion.

In the present invention, the operation of evaporating the wet sedimentation sample is preferably performed under conditions simulating natural wind speed; the operation of simulating the natural wind speed is preferably to place the wet sedimentation sample in a container and then blow clean air into the container; the blowing speed of the clean air is preferably (0-15L)/min, and more preferably 5-10L/min. The operation of blowing clean air into the container is not particularly limited in the present invention, and may be performed by an operation known to those skilled in the art. The source of the clean air is not particularly limited in the present invention, and the clean air known to those skilled in the art may be used.

In the invention, the concentration of the acidic solution is higher than 0.1mol/L, preferably 1-5 mol/L, and more preferably 2-4 mol/L; the acid solution does not contain precursor ions of volatile gases, and is preferably an oxalic acid solution and a citric acid solution. The source of the acidic solution is not particularly limited in the present invention, and it may be prepared by a commercially available product or a well-known preparation method well known to those skilled in the art. In the invention, when the concentration of the acid solution is in the range, the monitored alkaline volatile gas can be completely absorbed, and further the flux of the volatile gas can be monitored.

In the present invention, the container is preferably an annular etcher. The type of the container is not particularly limited in the present invention, and instruments and apparatuses well known to those skilled in the art may be used. The operation of wetting and drying the inner wall of the container with the acidic solution is not particularly limited in the present invention, and may be performed by an operation known to those skilled in the art.

In the present invention, the acidic solution preferably completely wets the inner wall of the container when the inner wall of the container is wetted. The operation of drying the container is not particularly limited in the present invention, and may be performed by an operation known to those skilled in the art. The operation of introducing the gas evaporated from the wet sedimentation sample into the container whose inner wall is wetted with the acidic solution and dried is not particularly limited in the present invention, and may be performed by an operation well known to those skilled in the art.

According to the invention, according to the acid-base neutralization principle, when the volatile gas to be monitored is alkaline gas, the gas is absorbed by acid-base neutralization by using a container which is wetted and dried by an acidic solution containing no precursor ions of the volatile gas.

And when the monitored volatile gas is acidic gas, introducing the gas evaporated by the wet sedimentation sample into a container with the inner wall wetted by alkaline solution and dried, and carrying out neutralization reaction to obtain a container for absorbing the gas.

In the present invention, the wet settled sample preferably further comprises filtration before being subjected to evaporation; the pore size of the filter membrane used for the filtration is preferably 0.22 or 0.45. mu.m. The source of the filter membrane is not particularly limited in the present invention, and a filter membrane known to those skilled in the art may be used. In the present invention, the wet sediment sample is filtered to remove particulate matter from the wet sediment sample in order to avoid calculation of the volatile gas flux that includes a portion of the particulate matter conversion.

In the present invention, the operation of evaporating the wet sedimentation sample is preferably the same as that when the volatile gas to be monitored is an alkaline gas, and will not be described in detail.

In the invention, the concentration of the alkaline solution is higher than 0.1mol/L, preferably 1-5 mol/L, and more preferably 2-4 mol/L; the alkaline solution does not contain precursor ions of volatile gases. The type of the alkaline solution is not particularly limited in the present invention, as long as it is ensured that it does not contain precursor ions of volatile gas. The source of the alkaline solution is not particularly limited in the present invention, and it may be formulated by a commercially available product or a well-known formulation method known to those skilled in the art. In the invention, when the concentration of the alkaline solution is in the range, the monitored acid volatile gas can be completely absorbed, and further the flux of the volatile gas can be monitored.

In the present invention, the container is preferably an annular etcher. The type of the container is not particularly limited in the present invention, and instruments and apparatuses well known to those skilled in the art may be used. The operation of wetting and drying the inside of the container with the alkaline solution is not particularly limited in the present invention, and may be performed by an operation known to those skilled in the art.

In the present invention, the alkaline solution preferably completely wets the inner wall of the container when the inner wall of the container is wetted. The operation of drying the container is not particularly limited in the present invention, and may be performed by an operation known to those skilled in the art. The operation of introducing the gas evaporated from the wet sedimentation sample into the container whose inner wall is wetted with the alkaline solution and dried in the present invention is not particularly limited, and may be performed by an operation known to those skilled in the art.

According to the invention, according to the acid-base neutralization principle, when the volatile gas to be monitored is acidic gas, the gas is absorbed by acid-base neutralization by using a container which is wetted and dried by an alkaline solution containing no precursor ions of the volatile gas.

When the volatile gas to be monitored is an acid gas and an alkaline gas, the monitoring may be performed preferably according to the above-mentioned operation when the volatile gas to be monitored is an acid gas and when the volatile gas to be monitored is an alkaline gas, which is not described herein again.

After obtaining the container for absorbing the gas, the invention adds the solvent into the container for absorbing the gas to dissolve the precursor ions in the absorbed gas to obtain the solution.

In the present invention, the solvent does not contain precursor ions of volatile gases, preferably deionized water. The source of the solvent is not particularly limited in the present invention, and a commercially available product known to those skilled in the art may be used. The amount of the solvent used in the present invention is not particularly limited, as long as the precursor ions in the absorbed gas are completely dissolved. In the present invention, the solvent is used to dissolve precursor ions of the absorbed gas.

After the solution is obtained, the concentration of precursor ions in the solution is tested, and the flux of the volatile gas is calculated.

The concentration of precursor ions of volatile gases in the solution is preferably tested by ion chromatography. The operation of the ion chromatography method is not particularly limited in the present invention, and may be performed by a method known to those skilled in the art.

In the present invention, the formula for calculating the flux of the volatile gas is preferably as shown in formula I:

wherein F is the flux of volatile gas and the unit is mg/m²(ii) a C is the concentration of precursor ions and has the unit of mu mol/L; b is the volume of the solvent, and the unit is mL; x is the molar mass of the volatile gas and the unit is g/mol; p is the wet sedimentation amount in mm; a is the volume of the wet settled sample in mL; and n is the molar ratio of the precursor ions to the volatile gas.

When the volatile gases to be monitored are acid gases and alkaline gases, B is the total amount of solvent used, i.e., the sum of the volumes of solvent that dissolves the acid gas precursor ions and solvent that dissolves the alkaline gas precursor ions.

According to the method, according to an acid-base neutralization principle, when the monitored volatile gas is alkaline gas, a container which is wetted and dried by an acid solution containing no precursor ions of the volatile gas is adopted to absorb the gas through acid-base neutralization; when the monitored volatile gas is acid gas, a container which is wetted and dried by alkaline solution containing no precursor ions of the volatile gas is used for absorbing the gas through acid-base neutralization; and controlling the concentration of the acidic solution and the alkaline solution to be higher than 0.1mol/L, completely absorbing volatile gas to be monitored in a container, dissolving the volatile gas in a solvent which does not contain precursor ions of the volatile gas to test the concentration of the precursor ions of the volatile gas, and further calculating the flux of wet settlement volatile gas.

The method provided by the invention can monitor and calculate the flux of volatile gas released in the evaporation stage by atmospheric wet settlement, has the advantages of simple operation steps, clear calculation method and easy popularization, can avoid the defect that the gas quantity released in the wet settlement evaporation process cannot be accurately and quantitatively distinguished in the prior art, and has high accuracy.

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Monitoring NH Release during rainwater Evaporation₃Flux, the steps were as follows:

(1) immediately collecting 20mL of rainwater sample in a rainwater collector after one rainfall event (the rainfall is 20mm) in Changchun city of Jilin province, and filtering by using a filter membrane of 0.22 mu m;

fixing a test tube by using an iron stand table, connecting the upper end of the test tube with an erosion device, fixing the erosion device by using the iron stand table, extracting 10mL of rainwater by using a liquid transfer gun, filtering the filtered sample, uniformly dripping the filtered sample into the test tube, blowing clean air into one side of the test tube at the speed of 5L/min, introducing gas evaporated from a 10mL wet sedimentation sample into an annular erosion device (URG-2000) with the inner wall being completely wetted and dried by 5mol/L oxalic acid solution, and carrying out neutralization reaction to obtain the erosion device for absorbing the gas;

(2) after the wet sedimentation sample is completely evaporated, stopping blowing clean air, taking off the corrosion device, adding 10mL of deionized water into the corrosion device, repeatedly reversing and shaking until ions in the corrosion device are completely dissolved in the deionized water to obtain a solution;

(3) testing NH in the solution obtained in the step (2) by adopting ion chromatography₄ ⁺The concentration of (2) is 250 mu mol/L;

calculating the rainfall release NH of the field according to the formula I₃The amount is:

example 2

Monitoring HONO flux released by snow evaporation process, the steps are as follows:

(1) after one-time snowfall event (the snowfall amount is 15mm) in Changchun city of Jilin province is finished, immediately collecting 50mL of snow samples in a collector, and filtering the snow samples by using a 0.22-micrometer filter membrane after the snow samples are completely melted at room temperature;

fixing a test tube by using an iron stand, connecting the upper end of the test tube with an erosion apparatus, fixing the erosion apparatus by using the iron stand, extracting 10mL of snow water by using a liquid-transferring gun, filtering the snow water to obtain a sample, uniformly dripping the sample into the test tube, blowing clean air into one side of the test tube at a speed of 5L/min, introducing gas evaporated from a 10mL wet sedimentation sample into an annular erosion apparatus (URG-2000) with the inner wall being completely wetted and dried by using 5mol/L potassium carbonate solution, and carrying out neutralization reaction to obtain an erosion apparatus for absorbing the gas;

(2) after the wet sedimentation sample is completely evaporated, stopping blowing clean air, taking off the corrosion device, adding 10mL of deionized water into the corrosion device, repeatedly reversing and shaking until ions in the corrosion device are completely dissolved in the deionized water to obtain a solution;

(3) testing NO in the solution obtained in the step (2) by adopting ion chromatography₂ ^-The concentration of (2) is 380 mu mol/L;

calculating the amount of HONO released by snowfall in the field according to formula I:

example 3

Monitoring NH release during dew evaporation₃And HONO flux, the steps are as follows:

(1) after one condensation event (the condensation amount is 0.3mm) in Changchun city of Jilin province is finished, 20mL of dew on plant leaves is immediately extracted by a needle, and then a filter membrane with the diameter of 0.22 mu m is used for filtering;

fixing a test tube (2) by using an iron stand table (1), sequentially connecting eroding devices (3) and (4) at the upper end of the test tube (2), fixing the eroding devices (3) and (4) by using the iron stand table (1), wherein the schematic diagram of the device is shown in figure 1, 1 is the iron stand table, 2 is the test tube, 3 and 4 are the eroding devices, 5 is a filtered wet sediment sample, and 6 is a clean air inlet;

pumping 10mL of snow water by using a pipette, filtering the snow water, uniformly dripping the snow water into a test tube (2), blowing clean air into one side of the test tube (2) at a speed of 5L/min, introducing gas evaporated from a 10mL wet sedimentation sample into an annular corrosion device 3(URG-2000) with the inner wall being completely wetted by 1mol/L citric acid solution and dried, carrying out neutralization reaction, and introducing the gas into an annular corrosion device 4(URG-2000) with the inner wall being wetted by 1mol/L potassium carbonate solution and dried, carrying out neutralization reaction, and obtaining corrosion devices 3 and 4 for absorbing the gas;

(2) after the wet sedimentation sample is completely evaporated, stopping blowing clean air, taking off the erosion apparatus, respectively adding 10mL of deionized water into the erosion apparatuses 3 and 4, repeatedly reversing and shaking until ions in the erosion apparatuses are completely dissolved in the deionized water to obtain a first solution and a second solution;

(3) testing NH in the first solution obtained in the step (2) by adopting ion chromatography₄ ⁺The second solution was tested for NO at a concentration of 160. mu. mol/L₂ ^-The concentration is 245 mu mol/L;

calculating the NH released by the dew according to the formula I₃The amount is:

calculating the amount of HONO released by the dew according to formula I:

from the above examples, it can be seen that the method provided by the present invention is capable of monitoring the flux of volatile gases released during evaporation by atmospheric wet deposition.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.