CN116625964A - Continuous detection method and system for total nitrogen in water - Google Patents
Continuous detection method and system for total nitrogen in water Download PDFInfo
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 144
- 238000001514 detection method Methods 0.000 title claims abstract description 87
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 72
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 60
- 239000000243 solution Substances 0.000 claims abstract description 50
- 230000029087 digestion Effects 0.000 claims abstract description 37
- 238000002156 mixing Methods 0.000 claims abstract description 35
- 239000007788 liquid Substances 0.000 claims abstract description 28
- 238000010438 heat treatment Methods 0.000 claims abstract description 25
- 238000000034 method Methods 0.000 claims abstract description 23
- 239000006260 foam Substances 0.000 claims abstract description 4
- 239000007789 gas Substances 0.000 claims abstract description 4
- 238000005259 measurement Methods 0.000 claims abstract description 4
- 238000006722 reduction reaction Methods 0.000 claims description 38
- 239000003795 chemical substances by application Substances 0.000 claims description 26
- 238000005086 pumping Methods 0.000 claims description 18
- DHMQDGOQFOQNFH-UHFFFAOYSA-N Glycine Chemical compound NCC(O)=O DHMQDGOQFOQNFH-UHFFFAOYSA-N 0.000 claims description 16
- 230000002572 peristaltic effect Effects 0.000 claims description 16
- 238000002835 absorbance Methods 0.000 claims description 15
- 239000012086 standard solution Substances 0.000 claims description 14
- 239000003638 chemical reducing agent Substances 0.000 claims description 11
- 238000005485 electric heating Methods 0.000 claims description 10
- 238000005192 partition Methods 0.000 claims description 10
- 239000004471 Glycine Substances 0.000 claims description 8
- 229910021550 Vanadium Chloride Inorganic materials 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims description 3
- 239000011259 mixed solution Substances 0.000 claims description 3
- RPESBQCJGHJMTK-UHFFFAOYSA-I pentachlorovanadium Chemical group [Cl-].[Cl-].[Cl-].[Cl-].[Cl-].[V+5] RPESBQCJGHJMTK-UHFFFAOYSA-I 0.000 claims description 3
- JRKICGRDRMAZLK-UHFFFAOYSA-L persulfate group Chemical group S(=O)(=O)([O-])OOS(=O)(=O)[O-] JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 3
- FDDDEECHVMSUSB-UHFFFAOYSA-N sulfanilamide Chemical compound NC1=CC=C(S(N)(=O)=O)C=C1 FDDDEECHVMSUSB-UHFFFAOYSA-N 0.000 claims description 3
- 230000006641 stabilisation Effects 0.000 claims description 2
- 238000011105 stabilization Methods 0.000 claims description 2
- 238000011481 absorbance measurement Methods 0.000 claims 1
- 229910052793 cadmium Inorganic materials 0.000 abstract description 9
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 abstract description 9
- 238000012544 monitoring process Methods 0.000 abstract description 7
- 239000003153 chemical reaction reagent Substances 0.000 abstract description 6
- 238000002347 injection Methods 0.000 abstract description 2
- 239000007924 injection Substances 0.000 abstract description 2
- 238000000691 measurement method Methods 0.000 abstract description 2
- 239000000523 sample Substances 0.000 description 28
- 230000018109 developmental process Effects 0.000 description 12
- 238000010586 diagram Methods 0.000 description 6
- 239000002699 waste material Substances 0.000 description 6
- 230000003287 optical effect Effects 0.000 description 4
- 230000031700 light absorption Effects 0.000 description 3
- 230000009977 dual effect Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000008092 positive effect Effects 0.000 description 2
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- IOVCWXUNBOPUCH-UHFFFAOYSA-M Nitrite anion Chemical compound [O-]N=O IOVCWXUNBOPUCH-UHFFFAOYSA-M 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- LECSHJWIACEDPZ-UHFFFAOYSA-N ethane-1,2-diamine naphthalene hydrochloride Chemical compound C(CN)N.C1=CC=CC2=CC=CC=C12.Cl LECSHJWIACEDPZ-UHFFFAOYSA-N 0.000 description 1
- 238000012851 eutrophication Methods 0.000 description 1
- 238000004401 flow injection analysis Methods 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 231100000053 low toxicity Toxicity 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- -1 polyethylene Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 239000012488 sample solution Substances 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000002798 spectrophotometry method Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—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
- G01N1/38—Diluting, dispersing or mixing samples
-
- 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
- G01N1/44—Sample treatment involving radiation, e.g. heat
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/20—Controlling water pollution; Waste water treatment
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- Physics & Mathematics (AREA)
- Biochemistry (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Investigating Or Analysing Materials By The Use Of Chemical Reactions (AREA)
- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
Abstract
The invention relates to the technical field of water quality detection, in particular to a method and a system for continuously detecting total nitrogen in water quality. The continuous detection system for total nitrogen in water quality comprises a control device, a sample pump, a digestion pump, a first liquid mixing device, a first heating device and a defoaming device, wherein the sample pump, the digestion pump, the first liquid mixing device, the first heating device and the defoaming device are communicated through pipelines and are used for eliminating foam and gas generated by a first solution, a reduction pump, a reduction device, a color development pump, a second liquid mixing device, a photoelectric detection device and the control device. The continuous detection system and method for total nitrogen in water quality adopt a mobile sample injection method, can realize real-time, continuous and point-by-point measurement, can be applied to the shipborne navigation process, and can solve the problem of reduction efficiency reduction of the cadmium column by continuously passing the cadmium column by the reagent compared with the traditional measurement method, and the accuracy of the shipborne online monitoring instrument is improved.
Description
Technical Field
The invention relates to the technical field of water quality detection, in particular to a method and a system for continuously detecting total nitrogen in water quality.
Background
Total nitrogen is an important indicator for measuring eutrophication of water. According to the standard HJ 668-2013, the method of flow injection of determination of total nitrogen in water quality, namely naphthalene ethylenediamine hydrochloride spectrophotometry, total nitrogen is oxidized into nitrate by an oxidant and then needs to be reduced into nitrite by a cadmium column. In practical application, the reduction efficiency of the cadmium column is reduced along with the increase of the use times, so that the reduction efficiency is unstable, the cadmium column needs to be replaced frequently, the cost of replacing accessories of the instrument is increased, and the accuracy is reduced. In the uv reduction scheme, the total nitrogen needs to be digested for a certain time before detection, which results in a longer time to measure one sample. When continuous navigation monitoring is performed in a water area in a shipborne mode, the total nitrogen data of the whole water area can become unrealistic due to the fact that the navigation speed of the ship is high.
Disclosure of Invention
In view of the above, the invention provides a method and a system for continuously detecting total nitrogen in water quality, which at least partially solve the problems in the prior art.
In order to achieve the above purpose, the present invention provides the following technical solutions:
the continuous detection system for total nitrogen in water quality is characterized by comprising a control device and a pipeline communicated with the control device:
the sample pump is used for pumping in a sample to be detected;
the digestion pump is used for pumping in a digestion agent;
the first liquid mixing device is used for mixing the sample to be detected and the digestion agent to form a solution I;
a first heating device for heating the first solution;
the defoaming device is used for eliminating foam and gas generated by the first solution;
the reducing pump is used for pumping a reducing agent into the first solution to form a second solution;
the reduction device is used for treating the second solution to perform reduction reaction to form a third solution;
the color development pump is used for pumping a color development agent into the solution III;
the second liquid mixing device is used for mixing the solution III and the color developing agent to form a solution IV;
a photodetection means for detecting absorbance of the continuously inflowing solution four;
and the control device is used for controlling the flow rates of the sample pump, the digestion pump, the reduction pump and the color development pump.
Preferably, the sample pump, digestion pump, reduction pump and color development pump are all single-channel peristaltic pumps, or any two of the peristaltic pumps are combined into one double-channel peristaltic pump.
Preferably, the flow ratio of the sample pump, the digestion pump, the reduction pump and the color development pump is (1-20): 1:1:1.
Preferably, the reduction device is an ultraviolet lamp reduction device or an electric heating reduction device.
Preferably, the photodetection device comprises a support and a light source disposed thereon:
a light source for providing incident light for detection;
the light splitting device is used for splitting the light rays of the light source into at least two paths including a detection light path and a reference light path;
the flow cuvette is arranged on a detection light path behind the light splitting device and comprises a liquid inlet and a liquid outlet for flowing in and discharging the solution IV;
the detection photoelectric sensor is arranged on a detection light path behind the flow cuvette;
and the reference photoelectric sensor is arranged on a reference light path behind the light splitting device.
Preferably, the detection photosensor and the reference photosensor are capable of detecting light intensity at a wavelength of 540 nm.
Preferably, the first liquid mixing device and the second liquid mixing device are of pipeline structures spirally wound on a round rod.
Preferably, the heating device comprises a pipeline structure spirally wound on a hollow cylinder and an electric heating rod arranged in the hollow cylinder.
Preferably, the heating temperature of the electric heating rod is 80-120 ℃.
Preferably, the digestion agent is persulfate, the reducing agent is vanadium chloride, and the color developing agent is a mixed solution of p-aminobenzenesulfonamide and 1-naphthalene-ethylene diamine dihydrochloride.
Preferably, the sample pump, the digestion pump, the reduction pump, the color development pump, the first liquid mixing device, the second liquid mixing device, the first heating device, the defoaming device, the reduction device and the photoelectric detection device are arranged in a first partition, the control device is arranged in a second partition, and the first partition is isolated from the second partition by a partition plate.
On the other hand, the invention provides a water quality total nitrogen continuous detection method based on the water quality total nitrogen continuous detection system, which is characterized by comprising the following steps of:
step 1, setting flow parameters of a sample pump, a digestion pump, a reduction pump and a color development pump; continuously pumping a sample to be detected, a digestion agent, a reducing agent and a color developing agent, and measuring the absorbance of the sample to be detected at the wavelength of 540 nm;
and step 2, calculating the corresponding total nitrogen concentration through a standard curve according to the absorbance of the sample to be detected at the wavelength of 540 nm.
Preferably, the step 1 is preceded by the further step of,
and A1, selecting glycine standard solutions with different concentrations to flow through the water quality total nitrogen continuous detection system, measuring the absorbance of 540nm wavelength light under the corresponding concentration, and establishing a concentration standard curve and a function of absorbance-total nitrogen concentration.
Preferably, the preparation method of the glycine standard solution in the step A1 is as follows:
glycine was used as a standard substance, and standard solutions having concentrations of 200. Mu.g/L, 400. Mu.g/L, 600. Mu.g/L, 800. Mu.g/L, and 1000. Mu.g/L were prepared, respectively.
Preferably, the light intensity I of 540nm wavelength is measured by a reference photosensor 0 The light intensity I with the wavelength of 540nm is measured by a detection photoelectric sensor 1 Calculating absorbance Y at 540nm wavelength according to Langerhans' law 540nm ＝log(I 0 /I 1 )。
Preferably, the method comprises the steps of,
the step 1 may further comprise, prior to the step 1,
step A2, selecting a standard solution to flow through the water quality total nitrogen continuous detection system, and recording a time difference t required from the start of pumping the standard solution to the stabilization of the absorbance value;
the step 2 may further comprise the step of,
step 3, when the continuous water quality total nitrogen detection system continuously detects water quality at different positions, recording the position information L output at each moment n n And total nitrogen concentration data D n And position L n Corresponding to the actual total nitrogen concentration data of D n+t 。
Compared with the prior art, the continuous detection system and method for total nitrogen in water quality have the following advantages and positive effects:
compared with the traditional measuring method, the continuous water quality total nitrogen detection system can be applied to the shipborne navigation process, reagents continuously pass through the cadmium column, the problem of reduction efficiency reduction of the cadmium column is solved, and the accuracy of the shipborne online monitoring instrument is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a continuous detection system for total nitrogen in water according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a second embodiment of a continuous detection system for total nitrogen in water according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of a photoelectric detection device in a continuous detection system for total nitrogen in water quality according to an embodiment of the present invention;
FIG. 4 is a schematic view of the light path of the photodetector illustrated in FIG. 3;
FIG. 5 shows calculated position D in the method for continuously detecting total nitrogen in water according to the embodiment of the invention n Schematic of actual total nitrogen concentration data.
Reference numerals illustrate:
1: peristaltic pump one, 11: peristaltic pump two, 2: tee one, 21: tee two, 22: tee joint III, 3: mixing circle one, 31: mixing circle two, 4: first heating means, 41: second heating device, 5: defoaming device, 6: check valve one, 61: check valve two, 7: ultraviolet digestion device, 8: photoelectric detection device, 9: control device, 13: spectroscopic apparatus, 14: flow cell, 15: reference photosensor, 16: detecting a photoelectric sensor, 17: a bracket, 18: light source, R1: digestion agent, R2: reducing agent, R3: developer, S: and (5) a sample to be detected.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
It should be noted that, without conflict, the following embodiments and features in the embodiments may be combined with each other; and, based on the embodiments in this disclosure, all other embodiments that may be made by one of ordinary skill in the art without inventive effort are within the scope of the present disclosure.
It is noted that various aspects of the embodiments are described below within the scope of the following claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the present disclosure, one skilled in the art will appreciate that one aspect described herein may be implemented independently of any other aspect, and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented and/or a method practiced using any number of the aspects set forth herein. In addition, such apparatus may be implemented and/or such methods practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein. The steps of the method described in the embodiments of the present invention, such as step one, step two, etc., are not intended to limit the sequence of the steps of the method.
Fig. 1 is a schematic diagram of an embodiment of a continuous water quality total nitrogen detection system according to an embodiment of the present invention, fig. 3 is a schematic diagram of a structure of a photoelectric detection device 8 in the continuous water quality total nitrogen detection system according to an embodiment of the present invention, fig. 4 is a schematic diagram of an optical path of the photoelectric detection device 8 in the drawings, and the continuous water quality total nitrogen detection system according to the embodiment of the present invention will now be described in detail with reference to fig. 1, 3 and 4.
The invention relates to a continuous detection system for total nitrogen in water quality, which comprises a control device 9 and a sample pump communicated through a pipeline, wherein the control device is used for pumping in a sample to be detected; the digestion pump is used for pumping in a digestion agent; the method comprises the steps of carrying out a first treatment on the surface of the The first liquid mixing device is used for mixing the sample to be detected and the digestion agent to form a solution I; a first heating device 4 for heating the first solution; a defoaming device 5 for eliminating foam and gas generated by the first solution; the reducing pump is used for pumping a reducing agent into the first solution to form a second solution; the reduction device is used for treating the second solution to perform reduction reaction to form a third solution; the color development pump is used for pumping a color development agent into the solution III; the second liquid mixing device is used for mixing the solution III and the color developing agent to form a solution IV; a photodetection means 8 for detecting absorbance of the continuously inflowing solution four; and the control device 9 is used for controlling the flow rates of the sample pump, the digestion pump, the reduction pump and the color development pump, collecting and analyzing the data of the photoelectric detection device 8 and outputting the total nitrogen concentration information of the detection sample.
Referring to FIG. 1, in this embodiment, the sample pump and digestion pump are combined into a dual path peristaltic pump 1, and the reduction pump and chromogenic pump are combined into a dual path peristaltic pump 11. In other embodiments, the sample pump, digestion pump, reduction pump, and chromogenic pump may also be separate single-pass peristaltic pumps.
In this embodiment, the first liquid mixing device and the second liquid mixing device are respectively a first mixing ring 3 and a second mixing ring 31, and the first mixing ring 3 and the second mixing ring 31 are respectively pipeline structures spirally wound on a round bar. The first heating device 4 comprises a pipeline structure spirally wound on a hollow cylinder and an electric heating rod arranged in the hollow cylinder, and the heating temperature of the electric heating rod is 80-120 ℃. In this embodiment, the reduction device has a pipe structure spirally wound around a hollow cylinder, and an ultraviolet lamp is disposed in the hollow cylinder. As shown in fig. 2, in embodiment 2, the reduction device is a second heating device 41, and the second heating device 41 includes a pipe structure spirally wound on a hollow cylinder and an electric heating rod disposed in the hollow cylinder, and the heating temperature of the electric heating rod is 60 ℃.
Referring to fig. 1, in this embodiment, a one-way valve 1, a one-way valve 61, a three-way valve 2, a three-way valve 21 and a three-way valve 22 are further provided, a peristaltic pump 1 pumps a sample to be detected and a digestion agent into a mixing ring 3 through the three-way valve 2 to mix, a solution one is obtained, the solution one sequentially flows through a first heating device 4 and a defoaming device 5, a solution two is obtained after heating and defoaming, a reducing passage of the solution two and the peristaltic pump 11 is communicated to an ultraviolet digestion device 7 through the three-way valve two, the reducing passage pumps the reducing agent into the ultraviolet digestion device 7, the reducing agent is mixed with the solution two and subjected to irradiation of an ultraviolet lamp to obtain a solution three, a developing passage of the solution three and the peristaltic pump two 11 is communicated to a mixing ring 31 through the three-way valve three, the developing passage pumps the developing agent into the mixing ring two 31, the developing agent is mixed with the solution three in the mixing ring 31 to obtain a solution four, the solution four flows into a photoelectric detection to be detected, and then is discharged to a waste liquid bag.
In this embodiment, peristaltic pump one 1, peristaltic pump two 11, mix circle one 3, mix circle two 31, first heating device 4, defoaming device 5, ultraviolet digestion device 7, photoelectric detection device 8 set up in subregion one, controlling means 9 sets up in subregion two, subregion one with subregion two keeps apart circuit, water route through a baffle, and the integrated level is high, convenient assembly, and is small, is fit for on-line analysis.
Referring to fig. 3 and 4, in the present embodiment, the photodetection device 8 includes a holder 17 and a sensor provided thereon: a light source 18 for providing incident light for detection, in this embodiment, the light source 18 is an LED white light with a wide spectrum range; a light splitting device 13 for splitting the light of the light source 18 into at least two paths including a detection light path and a reference light path; a flow cuvette 14 disposed on the detection light path behind the spectroscopic device 13, and the flow cuvette 14 including a liquid inlet and a liquid outlet for flowing in and discharging a solution four; a detection photosensor 16 provided on a detection light path after the flow cuvette 14; the reference photosensor 15 is disposed on a reference optical path after the spectroscopic device 13.
The flow cuvette 14 is a cuboid with a black polyethylene light-shielding shell wrapped outside, a cylindrical cavity is arranged inside, the horizontal optical path of the cavity can be set to be 0.5cm-2cm, and the optical path of 1cm is selected in the embodiment. And two opposite windows are arranged, one window is irradiated by a light source 18, and the other window is connected with a detection photoelectric sensor 16; a sample inlet and a waste discharge port are arranged above the flow cuvette 14, the sample inlet is connected with the heating device, and the waste discharge port is connected with the waste liquid bag.
After the light source 18 emits incident light, the incident light irradiates the light splitting sheet, the incident light is divided into two paths, one path is a reference light path, the reference light path directly irradiates the reference photoelectric sensor 15, and the detection result of the part can be used as a reference to eliminate the influence caused by the fluctuation of the light source 18; the other path of detection light path irradiates the flow cuvette 14, penetrates the solution to be detected and irradiates the detection photoelectric sensor 16, and the detection photoelectric sensor 16 converts the illumination intensity into the absorbance through the Langerhans' law so as to calculate the concentration of the substance to be detected in the sample solution.
In this embodiment, the digestion agent is persulfate
The reducing agent is vanadium chloride
The color developing agent is a mixed solution of para-aminobenzenesulfonamide and 1-naphthalene-ethylene diamine dihydrochloride
The detection reagent in the embodiment simplifies the formula of the detection reagent on the premise of ensuring the use of the national standard detection principle of total nitrogen, and has simple preparation, low toxicity, less reagent waste, mild reaction condition, short reaction time and quick aging.
The embodiment of the invention also provides a detection method based on the continuous detection system for total nitrogen in water quality, which comprises the following steps:
setting flow parameters of a sample pump, a digestion pump, a reduction pump and a color development pump, wherein the flow ratio of the sample pump to the digestion pump to the reduction pump to the color development pump is (1-20): 1:1:1,
preparing glycine standard solutions with different concentrations from 0 mug/L to 1000 mug/L;
glycine standard solutions with different concentrations are selected to flow through the water quality total nitrogen continuous detection system, the light absorption intensity of 540nm wavelength light under the corresponding concentration is measured, and a concentration standard curve and a function of absorbance-total nitrogen concentration are established;
in this step, the method for measuring and calculating the light absorption intensity is specifically as follows:
measurement of the light intensity I at 540nm wavelength by the reference photosensor 15 0 The light intensity I with the wavelength of 540nm is measured by the detection photosensor 16 1 Calculating absorbance Y at 540nm wavelength according to Langerhans' law 540nm ＝log(I 0 /I 1 )。
And under the set parameters of the first step, continuously pumping in a sample to be detected, measuring the light absorption intensity of the sample to be detected at the wavelength of 540nm, calculating the corresponding total nitrogen concentration through a concentration standard curve, and outputting the detection result.
Selecting a standard solution to flow through the water quality total nitrogen continuous detection system, and recording a time difference t required from the start of pumping the standard solution to the discharge of the detected waste liquid from the system; when the continuous water quality total nitrogen detection system continuously detects water quality at different positions, as shown in FIG. 5, position information L output at each position is recorded n And total nitrogen concentration data D n And calculate the position L n Actual total nitrogen concentration data bit D of (C) n+tt . Wherein L is n And D n The subscript n of (2) is time.
The continuous water quality total nitrogen detection system can be carried on various ships such as unmanned ships, environment-friendly ships and cruising ships in practical application, and can realize online monitoring of total nitrogen and total nitrogen in rivers and lakes when continuously sampling at different places, and can provide long-term continuous real-time monitoring data for biological monitoring and early warning of ecological disasters such as red tide, green tide and the like, so that forecasting timeliness and accuracy are improved.
The continuous detection system and method for total nitrogen in water quality have the following advantages and positive effects:
because the mobile sample injection method is adopted, real-time, continuous and point-by-point measurement can be realized, compared with the traditional measurement method, the continuous detection system for total nitrogen in water quality can be applied to the shipborne navigation process, reagents continuously pass through a cadmium column, the problem of reduction efficiency reduction of the cadmium column is solved, and the accuracy of the shipborne online monitoring instrument is improved.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present invention should be included in the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.
Claims (16)
1. The continuous detection system for total nitrogen in water quality is characterized by comprising a control device and a pipeline communicated with the control device:
the sample pump is used for pumping in a sample to be detected;
the digestion pump is used for pumping in a digestion agent;
the first liquid mixing device is used for mixing the sample to be detected and the digestion agent to form a solution I;
a first heating device for heating the first solution;
the defoaming device is used for eliminating foam and gas generated by the first solution;
the reducing pump is used for pumping a reducing agent into the first solution to form a second solution;
the reduction device is used for treating the second solution to perform reduction reaction to form a third solution;
the color development pump is used for pumping a color development agent into the solution III;
the second liquid mixing device is used for mixing the solution III and the color developing agent to form a solution IV;
a photodetection means for detecting absorbance of the continuously inflowing solution four;
and the control device is used for controlling the flow rates of the sample pump, the digestion pump, the reduction pump and the color development pump.
2. The continuous water quality total nitrogen detection system according to claim 1, wherein the sample pump, the digestion pump, the reduction pump and the color development pump are all single-channel peristaltic pumps or any two of the peristaltic pumps are combined into a double-channel peristaltic pump.
3. The continuous detection system of total nitrogen in water according to claim 1, wherein the flow ratio of the sample pump, the digestion pump, the reduction pump and the color development pump is (1-20): 1:1:1.
4. The continuous water quality total nitrogen detection system according to claim 1, wherein the reduction device is an ultraviolet lamp reduction device or an electric heating reduction device.
5. The continuous water quality total nitrogen detection system according to claim 1, wherein said photoelectric detection device comprises a bracket and a sensor disposed thereon:
a light source for providing incident light for detection;
the light splitting device is used for splitting the light rays of the light source into at least two paths including a detection light path and a reference light path;
the flow cuvette is arranged on a detection light path behind the light splitting device and comprises a liquid inlet and a liquid outlet for flowing in and discharging the solution IV;
the detection photoelectric sensor is arranged on a detection light path behind the flow cuvette;
and the reference photoelectric sensor is arranged on a reference light path behind the light splitting device.
6. The continuous detection system of total nitrogen in water according to claim 5, wherein said detection photosensor and reference photosensor are capable of detecting light intensity at 540nm wavelength.
7. The continuous water quality total nitrogen detecting system according to claim 1, wherein the first liquid mixing device and the second liquid mixing device are of a pipeline structure spirally wound on a round bar.
8. The continuous water quality total nitrogen detecting system according to claim 1, wherein said heating device comprises a pipe structure spirally wound on a hollow cylinder and an electric heating rod disposed in said hollow cylinder.
9. The continuous water quality total nitrogen detecting system according to claim 8, wherein the heating temperature of the electric heating rod is 80-120 ℃.
10. The continuous water quality total nitrogen detection system according to claim 1, wherein the digestion agent is persulfate, the reducing agent is vanadium chloride, and the color-developing agent is a mixed solution of p-aminobenzenesulfonamide and 1-naphthalene-ethylene diamine dihydrochloride.
11. The continuous water quality total nitrogen detection system according to claim 1, wherein the sample pump, the digestion pump, the reduction pump, the color development pump, the first liquid mixing device, the second liquid mixing device, the first heating device, the defoaming device, the reduction device and the photoelectric detection device are arranged in a first partition, the control device is arranged in a second partition, and the first partition is isolated from the second partition by a partition plate.
12. A method for continuously detecting total nitrogen in water based on the continuous detection system for total nitrogen in water according to any one of claims 1 to 11, comprising the steps of:
step 1, setting flow parameters of a sample pump, a digestion pump, a reduction pump and a color development pump; continuously pumping a sample to be detected, a digestion agent, a reducing agent and a color developing agent, and measuring the absorbance of the sample to be detected at the wavelength of 540 nm;
and step 2, calculating the corresponding total nitrogen concentration through a standard curve according to the absorbance of the sample to be detected at the wavelength of 540 nm.
13. The continuous detection method of total nitrogen in water according to claim 12, wherein the step 1 is preceded by the steps of,
and A1, selecting glycine standard solutions with different concentrations to flow through the water quality total nitrogen continuous detection system, measuring the absorbance of 540nm wavelength light under the corresponding concentration, and establishing a concentration standard curve and a function of absorbance-total nitrogen concentration.
14. The continuous detection method of total nitrogen in water according to claim 13, wherein the preparation method of the glycine standard solution in the step A1 is as follows:
glycine was used as a standard substance, and standard solutions having concentrations of 200. Mu.g/L, 400. Mu.g/L, 600. Mu.g/L, 800. Mu.g/L, and 1000. Mu.g/L were prepared, respectively.
15. The continuous detection method of total nitrogen in water according to claim 12, wherein the absorbance measurement method comprises the following steps:
measurement of 540nm wavelength light intensity I by reference photosensor 0 The light intensity I with the wavelength of 540nm is measured by a detection photoelectric sensor 1 Calculating absorbance Y at 540nm wavelength according to Langerhans' law 540nm ＝log(I 0 /I 1 )。
16. The continuous detection method of total nitrogen in water according to claim 12,
the step 1 may further comprise, prior to the step 1,
step A2, selecting a standard solution to flow through the water quality total nitrogen continuous detection system, and recording a time difference t required from the start of pumping the standard solution to the stabilization of the absorbance value;
the step 2 may further comprise the step of,
step 3, when the continuous water quality total nitrogen detection system continuously detects water quality at different positions, recording the position information L output at each moment n n And total nitrogen concentration data D n And position L n Corresponding to the actual total nitrogen concentration data of D n+t 。
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