CN107064029B - Online nitrous acid and nitric acid concentration measurement system and measurement method - Google Patents
Online nitrous acid and nitric acid concentration measurement system and measurement method Download PDFInfo
- Publication number
- CN107064029B CN107064029B CN201710079043.7A CN201710079043A CN107064029B CN 107064029 B CN107064029 B CN 107064029B CN 201710079043 A CN201710079043 A CN 201710079043A CN 107064029 B CN107064029 B CN 107064029B
- Authority
- CN
- China
- Prior art keywords
- absorption
- liquid
- conversion
- nitrite
- mixing chamber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- 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
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Investigating Or Analysing Materials By The Use Of Chemical Reactions (AREA)
Abstract
The invention discloses a real-time online measurement system and method for nitrous acid and nitric acid concentration, wherein the system comprises an external sample injection unit, a liquid phase chemical conversion unit and an optical absorption detection unit which are sequentially connected; the external sample injection unit is used for injecting nitrogen-containing compounds; the liquid phase chemical conversion unit is used for absorbing and converting the nitrogen-containing compound from the external sample introduction unit into nitrite; the optical absorption detection unit is used for converting the nitrite from the liquid phase chemical conversion unit into an ultraviolet-visible absorptive substance and carrying out optical detection; the system can realize simultaneous measurement of nitrous acid and nitric acid, and can eliminate interference of other gas-phase substances through parallel channels. The system can realize trace detection of nitrous acid and nitric acid in the atmosphere and trace monitoring of nitrous acid and nitric acid in a water body, the detection sensitivity is better than 10pptv and 0.03 mug/L, and the response time is less than 3-5min; the method can be used for the aspects of atmospheric environment, water body environment monitoring, experimental scientific research and the like.
Description
Technical Field
The invention relates to the field of atmospheric environment detection and experimental science research, in particular to a real-time online measurement system and a real-time online measurement method for nitrous acid and nitric acid concentration.
Background
Nitrous acid (HONO) is a trace amount of nitrogen-containing substances in the atmosphere and is also a relatively typical secondary pollutant, and its concentration can be used as an index for directly reflecting the pollution degree of urban atmosphere. Nitric acid (HNO) 3 ) Is an important oxidation product of nitrogen oxides in the atmosphere, can be generated by free radical reaction, can be generated by hydrolysis of nitrous oxide, and can influence the global environment through dry and wet sedimentation while influencing the nitrogen circulation of the atmosphere. With frequent urban dust haze events, research on gaseous nitrous acid and nitric acid becomes a hot spot problem increasingly, but high-precision measurement of gaseous nitrous acid and nitric acid is very difficult due to low concentration in the atmosphere, high reactivity and the like.
At present, a mature detection method for nitrous acid (HONO) mainly comprises a diffusion tube technology, a chemiluminescence method, a Dinitrophenylhydrazine (DNPH) -derived High Performance Liquid Chromatography (HPLC) method, a mass spectrometry (Mass spectrometry) method, a spectroscopic method (comprising UV-PF/LIF, fourier infrared spectroscopy (FTIR)) and the like; for nitric acid (HNO) 3 ) The concentration of gaseous nitric acid is determined by converting gaseous nitric acid into nitrate ions mainly by wet absorption, and then measuring nitrate ions by UV spectrometry/photometry, ion chromatography (Ion Chromatography, IC) or the like. However, most of the above methods have some limitations, on the one hand, the interference gas is more, so that the measured HONO concentration value may be inaccurate; on the other hand, the detection limit height is not satisfied for HONO measurement with low concentration in the daytime.
Therefore, a high-selectivity high-precision measuring method is developed for detecting HONO and HNO in the atmosphere in real time 3 The concentration, the estimated atmospheric oxidation potential and even the deep solution to the problem of atmospheric pollution in our country have potential effects and significance.
Disclosure of Invention
In order to overcome the defects and shortcomings of the prior detection technology, the invention develops a real-time online measurement system and a measurement method for the concentration of nitrous acid and nitric acid based on wet absorption, chemical conversion and optical absorption. The system can realize the treatment of gaseous nitrous acid (HONO) and nitric acid (HNO) in the atmosphere 3 ) The simultaneous measurement of the gas phase material has the characteristics of good linearity, low detection limit, good repeatability and the like, and meanwhile, the interference of other gas phase materials can be eliminated through parallel channels, so that the reliability is high. In addition, by replacing different sampling systems, the nitrite and nitrate concentration in the liquid phase can be synchronously measured on line, and the same effect as the detection of the gaseous substances can be achieved. The system can be used for atmospheric environment monitoring, experimental science research and the like. The measuring method adopts the device.
The invention aims at realizing the following technical scheme:
the system comprises an external sample injection unit, a liquid phase chemical conversion unit and an optical absorption detection unit which are sequentially connected; the external sample injection unit is used for injecting nitrogen-containing compounds; the liquid phase chemical conversion unit is used for absorbing and converting the nitrogen-containing compound from the external sample introduction unit into nitrite; the optical absorption detection unit is used for converting the nitrite from the liquid phase chemical conversion unit into an ultraviolet-visible absorptive substance and carrying out optical detection;
the liquid phase chemical conversion unit comprises a first liquid phase chemical conversion unit and a second liquid phase chemical conversion unit;
the optical absorption detection unit comprises a first optical absorption detection unit and a second optical absorption detection unit;
in the external sample injection unit, nitrous acid and nitric acid to be detected are communicated with the inlet end of the external sample injection unit, the external sample injection unit comprises two outlet ends, namely a first outlet end and a second outlet end, and the two outlet ends are respectively connected with the first liquid-phase chemical conversion unit and the second liquid-phase chemical conversion unit;
the rear end of the first liquid phase chemical conversion unit is connected with the first optical absorption detection unit, and the rear end of the second liquid phase chemical conversion unit is connected with the second optical absorption detection unit; the second optical absorption detection unit only can obtain the concentration of nitrite and nitrate generated by impurity conversion and is used as a background deduction item; the first optical absorption detection unit can obtain the concentration of nitrite and nitrate generated by impurity conversion in the system, and the concentration of nitrite and nitrate in the system is obtained by subtracting the background subtraction term of the second optical absorption detection unit.
According to the invention, the external sample injection unit comprises a gas phase sample injection unit and a liquid phase sample injection unit.
According to the invention, the gas phase sample introduction unit comprises a gas absorption device, wherein the gas absorption device comprises a first aerosol filtering device, a first absorption pipe, a second absorption pipe, a first liquid storage tank A and two-way valves; the first aerosol filtering device is connected with a first absorption tube, and the first absorption tube is connected with a second absorption tube; the first liquid outlet of the first liquid storage tank A is connected with a first absorption pipe; the second liquid outlet of the first liquid storage tank A is connected with a second absorption pipe; the first absorption tube is connected with the first outlet end through a first two-way valve, and the second absorption tube is connected with the second outlet end through a second two-way valve.
According to the invention, the gas phase sampling unit also comprises an air extracting device, wherein the air extracting device comprises an air extracting pump, a gas flow controller, a second aerosol filtering device and a safety bottle; the air pump is connected with the gas flow controller, the gas flow controller is connected with the second aerosol filtering device, and the second aerosol filtering device is connected with the safety bottle; the safety bottle is connected with a second absorption tube in the gas absorption device.
According to the invention, the liquid phase sampling unit comprises a second liquid storage tank S and a permeable membrane device, wherein the second liquid storage tank S is provided with two liquid outlets which are marked as a third liquid outlet and a fourth liquid outlet; the third liquid outlet is connected with the first outlet end through a third two-way valve, the fourth liquid outlet is connected with the inlet of the permeable membrane device, and the outlet of the permeable membrane device is connected with the second outlet end through a fourth two-way valve.
According to the invention, the first liquid-phase chemical conversion unit comprises a first absorption line and a first conversion line;
the first absorption line comprises a first mixing chamber, and an outlet of the first mixing chamber is connected with the optical absorption detection unit;
the first conversion circuit comprises a first conversion pipe, a second mixing chamber and a first buffer pool, and the outlet of the first conversion pipe is connected with the inlet of the second mixing chamber; the outlet of the second mixing chamber is connected with the inlet of the first buffer pool; the outlet of the first buffer pool is connected with an optical absorption detection unit;
the first liquid phase chemical conversion unit is connected with a first outlet end, the first outlet end is divided into two paths, one path is connected with an inlet of a first mixing chamber in the first absorption line, and the other path is connected with a first conversion pipe of the first conversion line.
According to the invention, the second liquid-phase chemical conversion unit comprises a second absorption line and a second conversion line;
the second absorption line comprises a third mixing chamber, and an outlet of the third mixing chamber is connected with the optical absorption detection unit;
the second conversion circuit comprises a second conversion pipe, a fourth mixing chamber and a second buffer pool, and the outlet of the second conversion pipe is connected with the inlet of the fourth mixing chamber; the outlet of the fourth mixing chamber is connected with the inlet of the second buffer pool; the outlet of the second buffer pool is connected with an optical absorption detection unit;
the second liquid phase chemical conversion unit is connected with a second outlet end, the second outlet end is divided into two paths, one path is connected with an inlet of a third mixing chamber in the second absorption line, and the other path is connected with a second conversion pipe of the second conversion line.
According to the invention, the liquid phase chemical conversion unit further comprises a third liquid storage tank B; the liquid of the third liquid storage tank B is respectively introduced into the first liquid-phase chemical conversion unit and the second liquid-phase chemical conversion unit before the first outlet end and the second outlet end are branched; alternatively, after branching the first and second outlet ends, respectively, before the first mixing chamber in the first absorption line, before the first conversion tube in the first conversion line, before the third mixing chamber in the second absorption line, before the second conversion tube in the second conversion line; or a combination of the two.
According to the invention, the liquid-phase chemical conversion unit further comprises a fourth liquid reservoir R, the liquid of which is introduced before the first mixing chamber in the first absorption line, between the first conversion pipe and the second mixing chamber of the first conversion line, before the third mixing chamber in the second absorption line, between the second conversion pipe and the fourth mixing chamber of the second conversion line, respectively.
According to the present invention, the optical absorption detection unit includes four optical absorption detection units, a light source, and a detector; the first optical absorption detection unit comprises a first absorption cell, and an outlet of the first mixing chamber is connected with an inlet of the first absorption cell; the second optical absorption detection unit comprises a second absorption tank, and the outlet of the first buffer tank is connected with the inlet of the second absorption tank; the third optical absorption detection unit comprises a third absorption cell, and an outlet of the third mixing chamber is connected with an inlet of the third absorption cell; the fourth optical absorption detection unit comprises a fourth absorption tank, and an outlet of the second buffer tank is connected with an inlet of the fourth absorption tank; the light sources are respectively connected with inlets of the four absorption tanks, and the detectors are respectively connected with outlets of the four absorption tanks.
According to the invention, the system further comprises 1 or more parallel channels for further eliminating the influence of interfering substances, each of which comprises an absorption tube, a conversion tube, two absorption cells, an infusion pump, a light source and a detector, the absorption tubes, conversion tubes, absorption cells, infusion pumps and detectors in the parallel channels being connected in the same manner as the respective components in the liquid phase chemical conversion unit and the optical absorption detection unit are connected and operated. And if the plurality of parallel channels are provided, the absorption pipes in the plurality of parallel channels are connected with the absorption pipe of the previous parallel channel.
According to the invention, the on-line monitoring system further comprises a computer control unit for controlling the light source intensity, the flow of the flow controller, the output flow of the infusion pump and the detection data of the acquisition detector.
According to the invention, the first aerosol filtering device and the second aerosol filtering device adopt a filter membrane or a collision removing system; the filter membrane material can be one or more of quartz, glass fiber or polytetrafluoroethylene, and the pore diameter of the filter membrane is 0.002-100 μm.
According to the invention, the liquid storage tank can adopt corrosion-resistant materials such as glass, plastic, polytetrafluoroethylene and the like, and the absorption liquid in the first liquid storage tank can adopt alkaline solutions (pH=7-14) such as sodium carbonate, sodium hydroxide, imidazole or ammonia water or neutral solutions such as water and the like, so as to efficiently absorb nitrous acid and nitric acid gas in the air; the liquid in the second liquid storage tank is a solution containing nitrite and nitrate; the buffer solution in the third liquid storage tank can be buffer solution such as phosphoric acid, carbonic acid, acetic acid, imidazole and the like, and is used for adjusting the pH value (pH value) of the absorption liquid; the reaction liquid in the fourth liquid storage tank can be a mixed solution of hydrochloric acid, p-aminobenzene sulfonamide and N- (1-naphthyl) -ethylenediamine.
According to the present invention, the absorption tube may be a spiral tube structure or a straight tube structure; the diameter of the spiral pipe is 1-10mm, the winding diameter range is 5-50mm, and the length is 10-200mm; the diameter range of the straight pipe is 1-100mm, and the length is 10-200mm.
According to the invention, the outside of the absorption tube is connected with the constant-temperature water bath, and the temperature is controlled by water circulation, and the temperature range is 10-50 ℃.
According to the invention, the safety bottle can be made of glass, plastic, polytetrafluoroethylene and other corrosion-resistant materials.
According to the present invention, the flow controller may employ a mass flow meter, a float flow meter, a needle valve, or a proportional solenoid valve, and the flow rate is 1 ml per minute to 100 liters per minute.
According to the invention, the pump may be a mechanical pump, a diaphragm pump or a piston pump, and the pumping speed is 1 ml/min to 100 l/min.
According to the invention, the conversion tube is a cadmium (Cd) conversion column, and is filled with cadmium beads with the particle size of 30-200 meshes.
According to the invention, the mixing chamber may be made of inert materials such as glass or quartz, and has a volume of 5 ml to 5 l.
According to the invention, the buffer tank can adopt a coil pipe or a solenoid reactor, and is made of glass, quartz, polytetrafluoroethylene (PTFE) or soluble Polytetrafluoroethylene (PFA) and the like.
According to the invention, the light source can adopt a halogen lamp, an LED lamp or a xenon lamp, and the output wavelength range is 200-1000nm.
According to the invention, the absorption cell can adopt a quartz absorption cell or a liquid optical fiber absorption cell, and the absorption optical path is 1cm-5m.
According to the invention, the detector is a diode or Charge Coupled Device (CCD) detector, which is a multiplex detector, and the number of the detectors is 1-10.
According to the invention, one or more liquid output pumps can be added into the pipeline according to the requirement, so that the liquid flow control and the better transportation in the pipeline are facilitated.
According to the invention, the liquid output pump may be one or more output pumps, and the multiple output pump may have 4 to 20 outputs. For example, the multi-output pump may be used for the output of liquid from a liquid reservoir.
According to the invention, peristaltic pumps, high-pressure constant-flow infusion pumps and microinjectors can be used as the liquid output pump, with a flow rate of 1 microliter per minute to 100 milliliters per minute.
The invention also provides a real-time online measurement method for the concentration of nitrous acid and nitric acid, which adopts the online measurement system and comprises the following steps:
(1) When the object to be detected is gas, absorbing the gas including nitrous acid and nitric acid gas by using alkaline or neutral absorption solution, and introducing the gas into the solution, namely solution C; when the object to be detected is nitrite or nitrate solution, directly introducing the solution, and marking the solution as solution C';
(2) Converting nitrate into nitrite, then converting nitrite into an absorbing substance with ultraviolet-visible property, and carrying out optical detection;
dividing the solution C or the solution C' into four paths, reducing and converting nitrate into nitrite by a first conversion tube in a first liquid phase chemical conversion unit, and then converting nitrite into an absorbing substance with ultraviolet-visible property by a second mixing chamber for optical detection to obtain the total concentration N of nitrite Total HONO The N is Total HONO Concentration of nitrite N in system Body, HONO Concentration N of nitrate-converted nitrite in+ System Body, HONO conversion (equal to the concentration N of nitrate in the System) Body, HNO3 ) Total concentration N of nitrite produced by conversion of + impurities Hybrid, HONO Total ；
The second path directly passes through a second mixing chamber in the first liquid phase conversion unit to obtain nitrite concentration N containing impurities Body, HONO+ impurity The N is Body, HONO+ impurity Concentration of nitrite N in system Body, HONO Concentration N of nitrite formed by conversion of+ impurity Hybrid, HONO ；
The third way is to convert possible impurity into nitrite through a second conversion tube in a second liquid phase chemical conversion unit, and then to convert nitrite into ultraviolet-visible absorptive substance through a fourth mixing chamber for optical detection to obtain total concentration N of nitrite generated by impurity conversion Hybrid, HONO Total The N is Hybrid, HONO Total Concentration N of nitrate converted nitrite in impurity Hybrid HONO conversion (equal to the concentration N of nitrate in impurities) Hetero, HNO3 ) Concentration N of nitrite produced by conversion of+ impurities Hybrid, HONO ；
The fourth path directly passes through a third mixing chamber of the second liquid phase conversion unit to obtain the concentration N of nitrite generated by impurity conversion Hybrid, HONO ；
Obtaining the concentration N of nitrite in the system through the difference value 1 of the second and fourth paths of measurement results Body, HONO The method comprises the steps of carrying out a first treatment on the surface of the The difference value 1 is further subtracted from the difference value 2 of the first and third paths of measurement results to obtain the concentration N of nitrate in the system Body, HNO3 。
The beneficial effects of the invention are as follows:
1. the monitoring system can realize simultaneous measurement of nitrous acid and nitric acid, and can eliminate interference of other gas-phase substances through parallel channels.
2. The monitoring system can realize trace detection of nitrous acid and nitric acid in the atmosphere and trace monitoring of nitrous acid and nitric acid in a water body, the detection sensitivity is better than 10pptv (for nitrous acid) and 0.03 mug/L (for nitric acid), the response time is less than 3-5min, and the accuracy is (+/-) (10% +10 pptv) (for nitrous acid) and (+/-) (10% +0.03 mug/L) (for nitric acid).
3. The monitoring system can be used for monitoring the atmospheric environment and the water environment, and can also be used for experimental scientific research and the like.
Drawings
FIG. 1 is a schematic diagram of the structure of the real-time online measurement system for nitrous acid and nitric acid concentrations of the present invention;
the device comprises a first aerosol filtering device, a first liquid storage tank A, a first absorption tube, a second absorption tube, a third liquid storage tank B, a safety bottle, a second aerosol filtering device, a flow controller, a gas pump, a computer, a second conversion tube, a fourth liquid storage tank R, a first conversion tube, a third mixing chamber, a fourth mixing chamber, a first mixing chamber, a second buffer tank, a first buffer tank, a light source, a third absorption tank, a fourth absorption tank, a second absorption tank, a first absorption tank, a second absorption tank, a detector, a liquid output pump, a permeable membrane device and a second liquid storage tank S.
FIG. 2 is a schematic diagram showing an introduction mode of a third liquid storage tank B in the real-time online measurement system of the nitrous acid and nitric acid concentration;
and 5, a third liquid storage tank B.
FIG. 3 is a schematic diagram of another introduction mode of a third liquid storage tank B in the real-time online measurement system of nitrous acid and nitric acid concentration according to the present invention;
and 5, a third liquid storage tank B.
FIG. 4 is a schematic diagram showing another introduction mode of a third liquid storage tank B in the real-time online measurement system of the nitrous acid and nitric acid concentration;
And 5, a third liquid storage tank B.
Detailed Description
The invention will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention. Further, it is understood that various changes and modifications of the invention will become apparent to those skilled in the art upon reading the description herein, and such equivalents are intended to fall within the scope of the invention as defined by the appended claims.
Example 1
The system comprises an external sample injection unit, a liquid phase chemical conversion unit and an optical absorption detection unit which are sequentially connected, wherein the external sample injection unit is connected with the liquid phase chemical conversion unit; the external sample injection unit is used for injecting nitrogen-containing compounds; the liquid phase chemical conversion unit is used for absorbing and converting the nitrogen-containing compound from the external sample introduction unit into nitrite; the optical absorption detection unit is used for converting the nitrite from the liquid phase chemical conversion unit into an ultraviolet-visible absorptive substance and carrying out optical detection;
the external sample injection unit comprises a gas phase sample injection unit and a liquid phase sample injection unit; when the gas-phase nitrous acid and nitric acid concentration is detected online, the third two-way valve and the fourth two-way valve are closed, the first two-way valve and the second two-way valve are opened, then the air pump 9 is opened, the flow of the flow controller 8 is set, the atmospheric components are pumped into the sampling assembly from the front end of the first aerosol filtering device 1, the particulate matters are removed, and the gaseous components enter the first absorption tube 3 and the second absorption tube 4; at the same time, the absorption liquid (alkaline solution (pH=7-14) such as sodium carbonate, sodium hydroxide, imidazole or ammonia water or neutral solution such as water) in the first liquid storage tank (A) 2 is controlled by a liquid output pump, and enters the first absorption tank 3 and the second absorption tank 4 respectively in two paths to be mixed with gaseous components for reaction, and mainly absorbs HONO and HNO therein 3 . The first outlet end of the external sample injection unit is connected with the first liquid phase chemical conversion unit, and the second outlet end of the external sample injection unit is connected with the second liquid phase chemical conversion unit; the liquid flowing out of the first outlet end enters the first liquid-phase chemical conversion unit, and the liquid flowing out of the second outlet end enters the second liquid-phase chemical conversion unit; the aerosol filter device adopts a polytetrafluoroethylene filter membrane, and the aperture is 0.2 mu m.
The liquid flowing out of the first outlet end and the second outlet end is mixed with buffer solution (buffer solution of phosphoric acid, carbonic acid, acetic acid, imidazole and the like) in a third liquid storage tank (B) 5, and the pH value of the liquid is regulated to 7-10; as shown in fig. 2, the mixing may be that the liquid flowing out of the third liquid storage tank (B) 5 may be introduced into the first liquid-phase chemical conversion unit and the second liquid-phase chemical conversion unit before the first and second outlet ends are branched, respectively; alternatively, as shown in fig. 3, after branching the first and second outlet ends, respectively, before the first mixing chamber 16 in the first absorption line, before the first conversion tube 13 in the first conversion line, before the third mixing chamber 14 in the second absorption line, before the second conversion tube 11 in the second conversion line; alternatively, as shown in fig. 4, one outlet end is introduced into the corresponding liquid-phase chemical conversion unit before branching, and the other outlet end is introduced into the mixing chamber in the corresponding absorption line and the conversion pipe of the corresponding conversion line, respectively, after branching;
The liquid introduced into the first outlet end and the second outlet end of the buffer solution in the third liquid storage tank (B) 5 respectively enters the first liquid phase chemical conversion unit and the second liquid phase chemical conversion unit and is directly mixed with the absorption liquid in the fourth liquid storage tank (R) 12, wherein the mixing can be before the liquid flowing out of the fourth liquid storage tank (R) 12 is respectively introduced into the first mixing chamber in the first absorption line, between the first conversion pipe and the second mixing chamber in the first conversion line, before the third mixing chamber in the second absorption line, and between the second conversion pipe and the fourth mixing chamber in the second conversion line;
for example, in the first absorption line, the liquid flowing out from the first outlet port is first introduced into the buffer solution in the third liquid storage tank (B) 5, and the pH value of the liquid is adjusted to 7-10; then introducing the absorption liquid (mixed solution of hydrochloric acid, p-aminobenzenesulfonamide and N- (1-naphthyl) -ethylenediamine) in the fourth liquid storage tank (R) 12), mixing, reacting to generate substances with visible light absorption, then introducing the substances into the first mixing chamber 16, fully mixing, and then introducing the substances into the first absorption tank 23; in the first conversion circuit, the liquid flowing out from the first outlet end is firstly introduced into the buffer solution in the third liquid storage tank (B) 5, and the pH value of the liquid is regulated to 7-10; then converting nitrate radical in the liquid into nitrite ion through a first converting pipe 13, then introducing the nitrite ion into an absorption liquid (mixed solution of hydrochloric acid, p-aminobenzene sulfonamide and N- (1-naphthyl) -ethylenediamine) in a fourth liquid storage tank (R) 12, mixing, reacting to generate substances with visible light absorption, then entering a second mixing chamber 17 for full mixing, then entering a first buffer tank 19, and finally entering a second absorption tank 24;
Similarly, in the second absorption line, the liquid flowing out from the second outlet end is firstly introduced into the buffer solution (imidazole) in the third liquid storage tank (B) 5, and the pH value of the liquid is regulated to 7-10; then introducing the absorption liquid (mixed solution of hydrochloric acid, p-aminobenzenesulfonamide and N- (1-naphthyl) -ethylenediamine) in the fourth liquid storage tank (R) 12), mixing, reacting to generate substances with visible light absorption, then introducing the substances into the third mixing chamber 14, fully mixing, and then introducing the substances into the third absorption tank 21; in the second conversion circuit, the liquid flowing out of the second outlet end is firstly introduced into the buffer solution in the third liquid storage tank (B) 5, and the pH value of the liquid is regulated to 7-10; then converting nitrate radical in the liquid into nitrite ion through a second conversion pipe 11, then introducing the nitrite ion into an absorption liquid (mixed solution of hydrochloric acid, p-aminobenzene sulfonamide and N- (1-naphthyl) -ethylenediamine) in a fourth liquid storage tank (R) 12, mixing, reacting to generate substances with visible light absorption, then fully mixing in a fourth mixing chamber 15, further entering a second buffer tank 18, and finally entering a fourth absorption tank 22;
light emitted by the light source 20 enters four absorption tanks 21, 22, 23 and 24 through four channels respectively, after liquid absorption, the residual light intensity is detected by a detector 25, and signals enter a computer 10 for data acquisition;
Wherein the total concentration N of nitrite is obtained by the absorption tank 24 Total HONO The N is Total HONO Concentration of nitrite N in system Body, HONO Concentration N of nitrate-converted nitrite in+ System Body, HONO conversion (equal to the concentration N of nitrate in the System) Body, HNO3 ) Total concentration N of nitrite produced by conversion of + impurities Hybrid, HONO Total ；
Obtaining nitrite concentration N containing impurities through absorption tank 23 Body, HONO+ impurity The N is Body, HONO+ impurity Concentration of nitrite N in system Body, HONO Concentration N of nitrite formed by conversion of+ impurity Hybrid, HONO ；
The total concentration N of nitrite generated by impurity conversion can be obtained by the absorption tank 22 Hybrid, HONO Total The N is Hybrid, HONO Total Concentration N of nitrate converted nitrite in impurity Hybrid HONO conversion (equal to the concentration N of nitrate in impurities) Hetero, HNO3 ) Concentration N of nitrite produced by conversion of+ impurities Hybrid, HONO ；
The concentration N of nitrite produced by impurity conversion can be obtained by the absorption tank 21 Hybrid, HONO ；
Obtaining the concentration N of nitrite in the system through the difference value 1 of the measurement results of the absorption tank 23 and the absorption tank 21 Body, HONO The method comprises the steps of carrying out a first treatment on the surface of the The difference value 1 is further subtracted from the difference value 2 of the measurement results of the absorption tank 24 and the absorption tank 22 to obtain the concentration N of the nitrate in the system Body, HNO3 。
In addition, the computer 10 can control the intensity of the light source 20, control the on-off of the two-way valve, and also can control the flow rate of each liquid of the absorption liquid, the buffer liquid, the reaction liquid and the four absorption channels by controlling the flow rate of each liquid output pump 26.
The liquid storage tank in the embodiment is made of glass materials.
In the embodiment, the absorption tube adopts a spiral tube structure; the diameter of the spiral pipe is 4-5mm, the winding diameter range is 10-20mm, and the length is 10-200mm.
In the embodiment, the outside of the absorption tube is connected with a constant-temperature water bath, and the temperature is controlled by water circulation, and the temperature range is 25-35 ℃.
The safety bottle in this embodiment is made of glass material.
The flow controller in this embodiment may employ a mass flow meter with a measurement range of 6 liters per minute.
In this embodiment, the pump is a diaphragm pump, and the pumping speed is 5-6 liters per minute.
The conversion tube in this example is a cadmium (Cd) conversion column, and is filled with cadmium beads with a particle size of 60-100 meshes.
In this embodiment, the mixing chamber is made of polytetrafluoroethylene and has a volume of 3 liters.
The buffer tank in this embodiment may be a coil or a solenoid reactor, and is made of Polytetrafluoroethylene (PTFE) and soluble Polytetrafluoroethylene (PFA).
In this embodiment, the light source uses a xenon lamp, and the output wavelength range is 200-1000nm.
In this embodiment, the absorption cell is a liquid optical fiber absorption cell, and the absorption optical path is 2.5m.
In this embodiment, the detectors are Charge Coupled Device (CCD) detectors, which are multiple detectors, and the number of detectors is 4.
In the embodiment, one or more liquid output pumps can be added into the pipeline according to the requirement, so that the liquid flow control and the better transportation in the pipeline are facilitated.
The liquid output pump in this embodiment may be one or more output pumps, and the multiple output pump may have 4 to 20 outputs. For example, in this embodiment a 12-way output pump is used, which may be used for the output of liquid from a reservoir.
The liquid output pump in this example is a peristaltic pump with a rotational speed of 1-50 revolutions per minute and a flow rate of 100 microliters per minute to 2 milliliters per minute.
In this embodiment, four absorption pools are provided, wherein two paths 21 and 22 are control groups, two paths 23 and 24 are experimental groups, and other absorption pool groups can be added at the back of the two groups as required to better remove interference. The configuration of the absorber cell set and subsequent detectors is the same as in the prior art systems.
Example 2
The system comprises an external sample injection unit, a liquid phase chemical conversion unit and an optical absorption detection unit which are sequentially connected, wherein the external sample injection unit is connected with the liquid phase chemical conversion unit; the external sample injection unit is used for injecting nitrogen-containing compounds; the liquid phase chemical conversion unit is used for absorbing and converting the nitrogen-containing compound from the external sample introduction unit into nitrite; the optical absorption detection unit is used for converting the nitrite from the liquid phase chemical conversion unit into an ultraviolet-visible absorptive substance and carrying out optical detection;
the external sample injection unit comprises a gas phase sample injection unit and a liquid phase sample injection unit; when the nitrite and nitrate concentration in the liquid phase is detected online, a third two-way valve and a fourth two-way valve are opened, a first two-way valve and a second two-way valve are closed, the solution to be detected in a second liquid storage tank (S) 28 is controlled by a liquid output pump, and liquid is respectively output from a first outlet end and a second outlet end of an external sample injection unit in two ways, wherein a permeable membrane device 27 is further arranged between the output of the liquid at the second outlet end, and water-soluble inorganic ions are used for passing;
the first outlet end of the external sample injection unit is connected with the first liquid phase chemical conversion unit, and the second outlet end of the external sample injection unit is connected with the second liquid phase chemical conversion unit; the liquid flowing out of the first outlet end enters the first liquid-phase chemical conversion unit, and the liquid flowing out of the second outlet end enters the second liquid-phase chemical conversion unit;
The liquid flowing out of the first outlet end and the second outlet end is mixed with buffer solution (buffer solution of phosphoric acid, carbonic acid, acetic acid, imidazole and the like) in a third liquid storage tank (B) 5, and the pH value of the liquid is regulated to 7-10; as shown in fig. 2, the mixing may be that the liquid flowing out of the third liquid storage tank (B) 5 may be introduced into the first liquid-phase chemical conversion unit and the second liquid-phase chemical conversion unit before the first and second outlet ends are branched, respectively; alternatively, as shown in fig. 3, after branching the first and second outlet ends, respectively, before the first mixing chamber 16 in the first absorption line, before the first conversion tube 13 in the first conversion line, before the third mixing chamber 14 in the second absorption line, before the second conversion tube 11 in the second conversion line; alternatively, as shown in fig. 4, one outlet end is introduced into the corresponding liquid-phase chemical conversion unit before branching, and the other outlet end is introduced into the mixing chamber in the corresponding absorption line and the conversion pipe of the corresponding conversion line, respectively, after branching;
the liquid introduced into the first outlet end and the second outlet end of the buffer solution in the third liquid storage tank (B) 5 respectively enters the first liquid phase chemical conversion unit and the second liquid phase chemical conversion unit and is directly mixed with the absorption liquid in the fourth liquid storage tank (R) 12, wherein the mixing can be before the liquid flowing out of the fourth liquid storage tank (R) 12 is respectively introduced into the first mixing chamber in the first absorption line, between the first conversion pipe and the second mixing chamber in the first conversion line, before the third mixing chamber in the second absorption line, and between the second conversion pipe and the fourth mixing chamber in the second conversion line;
For example, in the first absorption line, the liquid flowing out from the first outlet port is first introduced into the buffer solution in the third liquid storage tank (B) 5, and the pH value of the liquid is adjusted to 7-10; the absorption liquid introduced into the fourth liquid storage tank (R) 12 is mixed and reacts to generate substances with visible light absorption, and then the substances enter the first mixing chamber 16 for full mixing and further enter the first absorption tank 23; in the first conversion circuit, the liquid flowing out from the first outlet end is firstly introduced into the buffer solution in the third liquid storage tank (B) 5, and the pH value of the liquid is regulated to 7-10; then converting nitrate radical in the liquid into nitrite ion through a first converting pipe 13, then introducing the nitrite ion into the absorption liquid in a fourth liquid storage tank (R) 12, mixing, reacting to generate substances with visible light absorption, then entering a second mixing chamber 17 for full mixing, then entering a first buffer tank 19, and finally entering a second absorption tank 24;
similarly, in the second absorption line, the liquid flowing out from the second outlet end is firstly introduced into the buffer solution in the third liquid storage tank (B) 5, and the pH value of the liquid is regulated to 7-10; the absorption liquid introduced into the fourth liquid storage tank (R) 12 is mixed and reacts to generate substances with visible light absorption, and then the substances enter the third mixing chamber 14 for full mixing and further enter the third absorption tank 21; in the second conversion circuit, the liquid flowing out of the second outlet end is firstly introduced into the buffer solution in the third liquid storage tank (B) 5, and the pH value of the liquid is regulated to 7-10; then converting nitrate radical in the liquid into nitrite ion through a second conversion pipe 11, then introducing the nitrite ion into an absorption liquid in a fourth liquid storage tank (R) 12, mixing, reacting to generate substances with visible light absorption, then fully mixing in a fourth mixing chamber 15, further entering a second buffer tank 18, and finally entering a fourth absorption tank 22;
Light emitted by the light source 20 enters four absorption tanks 21, 22, 23 and 24 through four channels respectively, after liquid absorption, the residual light intensity is detected by a detector 25, and signals enter a computer 10 for data acquisition;
wherein the total concentration N of nitrite is obtained by the absorption tank 24 Total HONO The N is Total HONO Concentration of nitrite N in system Body, HONO Concentration N of nitrate-converted nitrite in+ System Body, HONO conversion (equal to the concentration N of nitrate in the System) Body, HNO3 ) Total concentration N of nitrite produced by conversion of + impurities Hybrid, HONO Total ；
Obtaining nitrite concentration N containing impurities through absorption tank 23 Body, HONO+ impurity The N is Body, HONO+ impurity Concentration of nitrite N in system Body, HONO Concentration N of nitrite formed by conversion of+ impurity Hybrid, HONO ；
The total concentration N of nitrite generated by impurity conversion can be obtained by the absorption tank 22 Hybrid, HONO Total The N is Hybrid, HONO Total Concentration N of nitrate converted nitrite in impurity Hybrid HONO conversion (equal to the concentration N of nitrate in impurities) Hetero, HNO3 ) Concentration N of nitrite produced by conversion of+ impurities Hybrid, HONO ；
The concentration N of nitrite produced by impurity conversion can be obtained by the absorption tank 21 Hybrid, HONO ；
Obtaining the concentration N of nitrite in the system through the difference value 1 of the measurement results of the absorption tank 23 and the absorption tank 21 Body, HONO The method comprises the steps of carrying out a first treatment on the surface of the The difference value 1 is further subtracted from the difference value 2 of the measurement results of the absorption tank 24 and the absorption tank 22 to obtain the concentration N of the nitrate in the system Body, HNO3 。
In addition, the computer 10 can control the intensity of the light source 20, control the on-off of the two-way valve, and also can control the flow rate of each liquid of the absorption liquid, the buffer liquid, the reaction liquid and the four absorption channels by controlling the flow rate of each liquid output pump 26.
In this embodiment, four absorption pools are provided, wherein two paths 21 and 22 are control groups, two paths 23 and 24 are experimental groups, and other absorption pool groups can be added at the back of the two groups as required to better remove interference. The configuration of the absorber cell set and subsequent detectors is the same as in the prior art systems.
In this embodiment, the selection of the components and the control of the flow rate are the same as in embodiment 1 unless otherwise specified.
According to the invention, the real-time online measurement of the concentration of nitrous acid and nitric acid in the atmosphere and the concentration of nitrite and nitrate in the liquid phase can be realized respectively through the two embodiments, and the detection sensitivity is better than 10pptv (for nitrous acid) and 0.03 mug/L (for nitric acid) respectively through changing the gas-liquid flow rate and the optical path length, the response time is less than 3-5min, and the accuracy is (10% +10 pptv) (for nitrous acid) and (10% +0.03 mug/L) (for nitric acid).
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (28)
1. The real-time online measurement system for the concentration of nitrous acid and nitric acid is characterized by comprising an external sample injection unit, a liquid phase chemical conversion unit and an optical absorption detection unit which are sequentially connected; the external sample injection unit is used for injecting nitrogen-containing compounds; the liquid phase chemical conversion unit is used for absorbing and converting the nitrogen-containing compound from the external sample introduction unit into nitrite; the optical absorption detection unit is used for converting the nitrite from the liquid phase chemical conversion unit into an ultraviolet-visible absorptive substance and carrying out optical detection;
the liquid phase chemical conversion unit comprises a first liquid phase chemical conversion unit and a second liquid phase chemical conversion unit;
the optical absorption detection unit comprises a first optical absorption detection unit and a second optical absorption detection unit;
in the external sample injection unit, nitrous acid and nitric acid to be detected are communicated with the inlet end of the external sample injection unit, the external sample injection unit comprises two outlet ends, namely a first outlet end and a second outlet end, and the two outlet ends are respectively connected with the first liquid-phase chemical conversion unit and the second liquid-phase chemical conversion unit;
The rear end of the first liquid phase chemical conversion unit is connected with the first optical absorption detection unit, and the rear end of the second liquid phase chemical conversion unit is connected with the second optical absorption detection unit; the second optical absorption detection unit only can obtain the concentration of nitrite and nitrate generated by impurity conversion and is used as a background deduction item; the first optical absorption detection unit can obtain the concentration of nitrite and nitrate generated by the conversion of impurities in the system, and the concentration of nitrite and nitrate in the system is obtained by deducting the background deduction term of the second optical absorption detection unit;
the first liquid-phase chemical conversion unit comprises a first absorption line and a first conversion line; the first absorption line comprises a first mixing chamber (16), and an outlet of the first mixing chamber (16) is connected with an optical absorption detection unit;
the first conversion circuit comprises a first conversion pipe (13), a second mixing chamber (17) and a first buffer tank (19), and the outlet of the first conversion pipe (13) is connected with the inlet of the second mixing chamber (17); the outlet of the second mixing chamber (17) is connected with the inlet of the first buffer tank (19); the outlet of the first buffer pool (19) is connected with an optical absorption detection unit;
The first liquid phase chemical conversion unit is connected with a first outlet end, the first outlet end is divided into two paths, one path is connected with an inlet of a first mixing chamber (16) in a first absorption line, and the other path is connected with a first conversion pipe (13) of the first conversion line;
the second liquid-phase chemical conversion unit comprises a second absorption line and a second conversion line; the second absorption line comprises a third mixing chamber (14), and an outlet of the third mixing chamber (14) is connected with an optical absorption detection unit;
the second conversion circuit comprises a second conversion pipe (11), a fourth mixing chamber (15) and a second buffer tank (18), and the outlet of the second conversion pipe (11) is connected with the inlet of the fourth mixing chamber (15); the outlet of the fourth mixing chamber (15) is connected with the inlet of the second buffer tank (18); the outlet of the second buffer pool (18) is connected with an optical absorption detection unit;
the second liquid-phase chemical conversion unit is connected with a second outlet end, the second outlet end is divided into two paths, one path is connected with an inlet of a third mixing chamber (14) in a second absorption line, and the other path is connected with a second conversion pipe (11) of the second conversion line;
The optical absorption detection unit comprises four optical absorption detection units, a light source (20) and a detector (25); the first optical absorption detection unit comprises a first absorption cell (23), and the outlet of the first mixing chamber (16) is connected with the inlet of the first absorption cell (23); the second optical absorption detection unit comprises a second absorption cell (24), and the outlet of the first buffer cell (19) is connected with the inlet of the second absorption cell (24); the third optical absorption detection unit comprises a third absorption cell (21), and the outlet of the third mixing chamber (14) is connected with the inlet of the third absorption cell (21); the fourth optical absorption detection unit comprises a fourth absorption cell (22), and the outlet of the second buffer cell (18) is connected with the inlet of the fourth absorption cell (22); the light sources are respectively connected with inlets of the four absorption tanks, and the detectors are respectively connected with outlets of the four absorption tanks;
the external sample injection unit comprises a gas phase sample injection unit and a liquid phase sample injection unit.
2. The system according to claim 1, wherein the gas-phase sampling unit comprises a gas absorbing device comprising a first aerosol filtering device (1), a first absorbing tube (3), a second absorbing tube (4), a first liquid storage tank a (2) and two-way valves; the first aerosol filtering device (1) is connected with a first absorption tube (3), and the first absorption tube (3) is connected with a second absorption tube (4); the first liquid outlet of the first liquid storage tank A (2) is connected with a first absorption pipe (3); the second liquid outlet of the first liquid storage tank A (2) is connected with a second absorption pipe (4); the first absorption tube (3) is connected with the first outlet end through a first two-way valve, and the second absorption tube (4) is connected with the second outlet end through a second two-way valve.
3. The system according to claim 2, wherein the gas-phase sampling unit further comprises a gas extraction device comprising a gas extraction pump (9), a gas flow controller (8), a second aerosol filter device (7) and a safety bottle (6); the air pump (9) is connected with the gas flow controller (8), the gas flow controller (8) is connected with the second aerosol filtering device (7), and the second aerosol filtering device (7) is connected with the safety bottle (6); the safety bottle (6) is connected with a second absorption tube (4) in the gas absorption device.
4. The system according to claim 1, wherein the liquid-phase sampling unit comprises a second liquid storage tank S (28) and a permeable membrane device (27), and the second liquid storage tank S (28) is provided with two liquid outlets, namely a third liquid outlet and a fourth liquid outlet; the third liquid outlet is connected with the first outlet end through a third two-way valve, the fourth liquid outlet is connected with the inlet of the permeable membrane device (27), and the outlet of the permeable membrane device (27) is connected with the second outlet end through a fourth two-way valve.
5. The system according to claim 1, characterized in that the liquid phase chemical conversion unit further comprises a third liquid storage tank B (5); the liquid of the third liquid storage tank B (5) is respectively introduced into the first liquid-phase chemical conversion unit and the second liquid-phase chemical conversion unit before the first outlet end and the second outlet end are branched; or, after branching at the first and second outlet ends, respectively, before the first mixing chamber (16) in the first absorption line, before the first conversion tube (13) in the first conversion line, before the third mixing chamber (14) in the second absorption line, before the second conversion tube (11) in the second conversion line; or a combination of both modes of introduction.
6. The system according to any one of claims 1-5, characterized in that the liquid-phase chemical conversion unit further comprises a fourth liquid reservoir R (12), the liquid of the fourth liquid reservoir R (12) being introduced before the first mixing chamber (16) in the first absorption line, between the first conversion tube (13) and the second mixing chamber (17) of the first conversion line, before the third mixing chamber (14) in the second absorption line, between the second conversion tube (11) and the fourth mixing chamber (15) of the second conversion line, respectively.
7. The system of any one of claims 1-5, further comprising 1 or more parallel channels for further eliminating the effects of interfering substances, each parallel channel comprising an absorber tube, a converter tube, two absorber cells, an infusion pump, a light source, and a detector, the absorber tubes, the converter tubes, the absorber cells, the infusion pump, and the detector in the parallel channels being connected in the same manner as the corresponding components in the liquid phase chemical conversion unit and the optical absorption detection unit; and if the plurality of parallel channels are provided, the absorption pipes in the plurality of parallel channels are connected with the absorption pipe of the previous parallel channel.
8. The system of any one of claims 1-5, wherein the on-line measurement system further comprises a computer control unit for controlling the light source intensity, the flow rate of the flow controller, the output flow rate of the infusion pump, and the collection of the detection data of the detector.
9. A system according to claim 3, wherein the first and second aerosol filtration devices employ a filter membrane or a collision removal system; the filter membrane is made of one or more of quartz, glass fiber or polytetrafluoroethylene, and the pore diameter of the filter membrane is 0.002-100 mu m.
10. The system of claim 2, wherein the first liquid storage tank is made of glass or plastic, and the absorption liquid in the first liquid storage tank is made of sodium carbonate, sodium hydroxide, imidazole, ammonia water or water, and is used for efficiently absorbing nitrous acid and nitric acid gases in air.
11. The system of claim 4, wherein the second reservoir is made of glass or plastic, and the liquid in the second reservoir is a solution containing nitrite and nitrate.
12. The system of claim 5, wherein the third reservoir is made of glass or plastic, and the buffer in the third reservoir is made of phosphoric acid, carbonic acid, acetic acid or imidazole buffer solution for adjusting the ph of the absorption liquid.
13. The system of claim 6, wherein the fourth reservoir is made of glass or plastic, and the reaction solution in the fourth reservoir is a mixed solution of hydrochloric acid, p-aminobenzenesulfonamide and N- (1-naphthyl) -ethylenediamine.
14. A system according to claim 2 or 3, wherein the absorber tube is of a coiled tube construction or a straight tube construction; the pipe diameter of the spiral pipe is 1-10mm, the winding diameter range is 5-50mm, and the length is 10-200mm; the diameter range of the straight pipe is 1-100mm, and the length is 10-200mm.
15. A system according to claim 2 or 3, characterized in that the absorption tube is connected externally to a thermostatic water bath, the temperature being controlled by water circulation, the temperature being in the range of 10-50 ℃.
16. A system according to claim 3, wherein the safety bottle is glass or plastic.
17. A system according to claim 3, wherein the gas flow controller employs a mass flow meter, float flow meter, needle valve or proportional solenoid valve at a flow rate of 1 milliliter per minute to 100 liters per minute.
18. A system according to claim 3, wherein the pump is a mechanical, diaphragm or piston pump with a pumping rate of 1 ml/min to 100 l/min.
19. The system of claim 1, wherein the conversion tube is a cadmium (Cd) conversion column packed with 30-200 mesh size cadmium beads.
20. The system of claim 1, wherein the mixing chamber is glass or quartz and has a volume of 5 ml to 5 l.
21. The system of claim 1, wherein the buffer tank is a coiled tube or a solenoid reactor, and is made of glass, quartz, polytetrafluoroethylene (PTFE) or soluble Polytetrafluoroethylene (PFA).
22. The system of claim 1, wherein the light source is a halogen lamp, an LED lamp, or a xenon lamp, and the output wavelength ranges from 200 nm to 1000nm.
23. The system of claim 1, wherein the absorption cell is a quartz absorption cell or a liquid fiber absorption cell, and the absorption optical path is 1cm-5m.
24. The system of claim 1, wherein the detector is a diode or Charge Coupled Device (CCD) detector, is a multiplex detector, and is 1-10 in number.
25. The system of any one of claims 1-5, wherein one or more liquid delivery pumps are added to the tubing as needed to facilitate liquid flow control and better delivery in the tubing.
26. The system of claim 25, wherein the liquid output pump is one or more output pumps, the multiple output pump having 4 to 20 outputs.
27. The system of claim 26, wherein the fluid output pump is a peristaltic pump, a high pressure constant flow infusion pump, and a microinjector, at a flow rate of 1 microliter per minute to 100 milliliters per minute.
28. A method for real-time online measurement of nitrous acid and nitric acid concentrations, characterized in that the method employs an online measurement system according to any one of claims 1-27, comprising the steps of:
(1) When the object to be detected is gas, absorbing the gas including nitrous acid and nitric acid gas by using alkaline or neutral absorption solution, and introducing the gas into the solution, namely solution C; when the object to be detected is nitrite or nitrate solution, directly introducing the solution, and marking the solution as solution C';
(2) Converting nitrate into nitrite, then converting nitrite into an absorbing substance with ultraviolet-visible property, and carrying out optical detection;
dividing the solution C or the solution C' into four paths, reducing and converting nitrate into nitrite by a first conversion tube in a first liquid phase chemical conversion unit, and then converting nitrite into an absorbing substance with ultraviolet-visible property by a second mixing chamber for optical detection to obtain the total concentration N of nitrite Total HONO The N is Total HONO Concentration of nitrite N in system Body, HONO Concentration N of nitrate-converted nitrite in+ System Body, HONO conversion Total concentration N of nitrite produced by conversion of + impurities Hybrid, HONO Total ；
The second path directly passes through a second mixing chamber in the first liquid phase conversion unit to obtain nitrite concentration N containing impurities Body, HONO+ impurity The N is Body, HONO+ impurity Concentration of nitrite N in system Body, HONO Concentration N of nitrite formed by conversion of+ impurity Hybrid, HONO ；
The third way is to convert possible impurity into nitrite through a second conversion tube in a second liquid phase chemical conversion unit, and then to convert nitrite into ultraviolet-visible absorptive substance through a fourth mixing chamber for optical detection to obtain total concentration N of nitrite generated by impurity conversion Hybrid, HONO Total The N is Hybrid, HONO Total Concentration N of nitrate converted nitrite in impurity Hybrid HONO conversion Concentration N of nitrite produced by conversion of+ impurities Hybrid, HONO ；
The fourth path directly passes through a third mixing chamber of the second liquid phase conversion unit to obtain the concentration N of nitrite generated by impurity conversion Hybrid, HONO ；
Obtaining the system through the difference value 1 of the second and fourth paths of measurement results Concentration of nitrite N Body, HONO The method comprises the steps of carrying out a first treatment on the surface of the The difference value 1 is further subtracted from the difference value 2 of the first and third paths of measurement results to obtain the concentration N of nitrate in the system Body, HNO3 。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710079043.7A CN107064029B (en) | 2017-02-14 | 2017-02-14 | Online nitrous acid and nitric acid concentration measurement system and measurement method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710079043.7A CN107064029B (en) | 2017-02-14 | 2017-02-14 | Online nitrous acid and nitric acid concentration measurement system and measurement method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107064029A CN107064029A (en) | 2017-08-18 |
| CN107064029B true CN107064029B (en) | 2023-10-17 |
Family
ID=59598205
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710079043.7A Active CN107064029B (en) | 2017-02-14 | 2017-02-14 | Online nitrous acid and nitric acid concentration measurement system and measurement method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107064029B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108229092B (en) * | 2018-01-09 | 2023-09-12 | 南京大学 | Atmospheric pollution simulation prediction algorithm for increasing liquid phase chemistry and wet sedimentation process |
| CN109001364B (en) * | 2018-09-26 | 2020-01-21 | 华东师范大学 | Double-channel sampling atmosphere HONO determination system and method |
| CN110411967A (en) * | 2019-09-03 | 2019-11-05 | 南京信息工程大学 | The measuring system of gaseous state nitrous acid in a kind of atmosphere |
| CN112666305B (en) * | 2020-12-07 | 2024-05-03 | 吉林建筑大学 | Method for monitoring flux of volatile gas released in wet sedimentation evaporation process |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0849358A2 (en) * | 1996-11-25 | 1998-06-24 | Wilbur Dr. Campbell | Nitrate detection, measurement, and treatment system |
| US5858792A (en) * | 1996-08-22 | 1999-01-12 | University Of South Florida | Method for measuring nitrite and nitrate in aqueous medium |
| CN102498395A (en) * | 2009-08-07 | 2012-06-13 | 哈希公司 | Determination of nitrate/nitrite concentration in water by photochemical reduction |
| CN106290163A (en) * | 2016-07-21 | 2017-01-04 | 中国科学院化学研究所 | Dinitrogen pentoxide and concentration of nitric acid on-line monitoring system and monitoring method in a kind of air |
| CN206618679U (en) * | 2017-02-14 | 2017-11-07 | 中国科学院化学研究所 | A kind of nitrous acid and concentration of nitric acid real-time online measuring system |
-
2017
- 2017-02-14 CN CN201710079043.7A patent/CN107064029B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5858792A (en) * | 1996-08-22 | 1999-01-12 | University Of South Florida | Method for measuring nitrite and nitrate in aqueous medium |
| EP0849358A2 (en) * | 1996-11-25 | 1998-06-24 | Wilbur Dr. Campbell | Nitrate detection, measurement, and treatment system |
| CN102498395A (en) * | 2009-08-07 | 2012-06-13 | 哈希公司 | Determination of nitrate/nitrite concentration in water by photochemical reduction |
| CN106290163A (en) * | 2016-07-21 | 2017-01-04 | 中国科学院化学研究所 | Dinitrogen pentoxide and concentration of nitric acid on-line monitoring system and monitoring method in a kind of air |
| CN206618679U (en) * | 2017-02-14 | 2017-11-07 | 中国科学院化学研究所 | A kind of nitrous acid and concentration of nitric acid real-time online measuring system |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107064029A (en) | 2017-08-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107064029B (en) | Online nitrous acid and nitric acid concentration measurement system and measurement method | |
| CN102445442B (en) | Intelligent general type mercury measuring device and detection method thereof | |
| CN106290163B (en) | Dinitrogen pentoxide and concentration of nitric acid on-line monitoring system and monitoring method in a kind of atmosphere | |
| Bianchi et al. | On-line determination of ammonia at low pptv mixing ratios in the CLOUD chamber | |
| Liu et al. | Analytical chemistry in a drop | |
| CN106596439B (en) | Equipment and method for simultaneously measuring nitrous acid, ozone and nitrogen dioxide in air | |
| CN106769929B (en) | Atmospheric gaseous nitric acid online measurement method and device based on flow injection analysis | |
| CN109406705A (en) | A kind of liquid chromatogram combination type organic carbon detector and its application method | |
| CN108037115B (en) | Sulfur dioxide detection system and detection method | |
| CN103499558A (en) | System and method for determining mercury concentration in water | |
| Oms et al. | Continuous monitoring of atmospheric HCl, HNO2, HNO3 and SO2 by wet-annular denuder air sampling with on-line chromatographic analysis | |
| CN105259166A (en) | Formaldehyde detection device and method | |
| Dasgupta et al. | Diffusion scrubber-based field measurements of atmospheric formaldehyde and hydrogen peroxide | |
| Pereira et al. | Mrasurement of Atmospheric Formaldehyde Using a Drop Collector and In-Situ Colorimetry | |
| CN112378905A (en) | Accurate online monitoring method and system for ammonia content in ambient air | |
| Komazaki et al. | Automated measurement system for H2O2 in the atmosphere by diffusion scrubber sampling and HPLC analysis of Ti (IV)–PAR–H2O2 complex | |
| CN102980858A (en) | Small-size sequential injection nitride analysis system | |
| CN203941100U (en) | Gas phase molecular absorption spectrometer with carrier gas purification plant | |
| CN206515230U (en) | It is a kind of at the same measure air in nitrous acid, ozone, the equipment of nitrogen dioxide | |
| CN104792704A (en) | Continuous synchronous real-time on-line determination method and instrument for three indexes of TOC, TN and TP | |
| CN206618679U (en) | A kind of nitrous acid and concentration of nitric acid real-time online measuring system | |
| US20120149122A1 (en) | Device and method for determining the concentration of a compound in an aqueous or gaseous phase | |
| US20100281950A1 (en) | Method and apparatus for analysis of mixed streams | |
| Francois et al. | Development of an online analyzer of atmospheric H2O2 and several organic hydroperoxides for field campaigns | |
| Jansen et al. | Miniaturization of solid-phase reactors for on-line post-column derivatization in narrow-bore liquid chromatography |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |