A sulfide detection device based on gas phase molecules and a method of use

Abstract

The present invention relates to a sulfide detection device based on gas phase molecules, comprising: a sampling device, a dosing device, a gas generating device, an air generating device, a gas-liquid separation device, a waste liquid receiving device, a gas drying device, a detection device and a waste gas absorption device; and also comprising an interference removal device; the interference removal device comprises a hydrogen peroxide dosing tube, a hydrogen peroxide dosing pump and a mixing tube winding rack; a mixing tube is wound on the mixing tube winding rack; the sampling device comprises an automatic sampler and a sample injection pump; the dosing device comprises a six-way valve, an acid injection pump and an acid injection tube. The beneficial effects of the present invention are: the sulfide detection device based on gas phase molecules is suitable for various types of wastewater detection, and can efficiently and quickly reduce the positive interference of sulfite in sulfide detection; the sulfide detection device based on gas phase molecules is reliable and stable, and an interference elimination device can be added to the original gas phase molecule absorption spectrometer, which is easy to implement.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical analysis instruments, and in particular relates to a sulfide detection device based on gas phase molecules and a use method thereof. Background Art

[0002] Gas phase molecular absorption spectroscopy is a simple and rapid analytical method. It uses the absorption of light of a specific wavelength by ground state gas molecules, and the relationship between the absorption intensity and the concentration of the ground state gas molecules conforms to the Lambert-Beer law for quantitative analysis. Gas phase molecular absorption spectroscopy has high accuracy, high sensitivity, rapidity and convenience, and has been widely used in the field of water quality testing. At present, it is mainly used in the detection of sulfide, ammonia nitrogen, total nitrogen, nitrate nitrogen, nitrite nitrogen, Kjeldahl nitrogen, etc., and there are corresponding detection standards.

[0003] The application of gas phase molecular absorption spectrometry in sulfide detection is relatively mature, and there are corresponding standards (HJ / T200-2005). The analytical principle of gas phase molecular absorption spectrometry is to instantly convert sulfide into H2S gas in a 5% to 10% phosphoric acid medium, and use air to load H2S gas into the absorption tube of the gas phase molecular absorption spectrometer. The absorbance measured at wavelengths such as 202.6nm and the concentration of sulfide obey Beer's law. However, in the actual detection process of sulfide, sulfite interferes greatly with its detection. After sulfite enters the instrument with the sample, the sulfurous acid generated by phosphoric acid acidification is decomposed into SO2 and H2O by air blowing. SO2 gas and the H2S gas to be tested are brought into the absorption tube of the gas phase molecular absorption spectrometer by air. Since the absorption wavelength of H2S is 202.6nm, and SO2 also absorbs in the ultraviolet absorption band of 200nm to 230nm, the detection results show a significant positive deviation.

[0004] The standard (HJ / T200-2005) mentions that sulfite interference can be masked with 30% hydrogen peroxide. According to the interference elimination method in the standard, take an appropriate amount of water (sulfur content ≤ 200 micrograms) in a 50mL stoppered colorimetric tube, add 2-10mL zinc carbonate flocculant, add water to the mark, shake well, draw 10mL to the center of a mixed cellulose filter (pore size 3 microns), and wash the precipitate 5-8 times with zinc acetate-sodium acetate mixed washing liquid. Use tweezers to put the filter membrane into the lower part of the sample reaction bottle, with the side without precipitation against the bottle wall, add 2 drops of 30% hydrogen peroxide, seal the reaction bottle cap, add 10mL 10% phosphoric acid solution, and shake the reaction bottle vertically for 1-2 minutes. After the precipitation is dissolved, introduce carrier gas and measure the absorbance. The presence of reducing substances such as sulfites will seriously interfere with the determination of sulfides. The methods to eliminate interference are very complicated and difficult to control. In addition, the pretreatment methods in environmental standards require manual operation, which is too complicated and time-consuming. However, none of the existing commercially available devices have automatic pretreatment devices. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a sulfide detection device based on gas phase molecules and a method of use.

[0006] The sulfide detection device based on gas phase molecules comprises a sampling device, a dosing device, a gas generating device, an air generating device, a gas-liquid separation device, a waste liquid receiving device, a gas drying device, a detection device and a waste gas absorbing device; and also comprises an interference removal device; the interference removal device comprises a hydrogen peroxide dosing tube, a hydrogen peroxide dosing pump and a mixing tube winding rack; a mixing tube is wound on the mixing tube winding rack; the sampling device comprises an automatic sampler and a sample injection pump; the dosing device comprises a six-way valve, an acid injection pump and an acid injection tube;

[0007] The output end of the automatic sampler is connected to the inlet of the sample injection pump, the outlet of the sample injection pump is connected to the sample inlet of the mixing tube, the hydrogen peroxide dosing tube is connected to the inlet of the hydrogen peroxide dosing pump, and the outlet of the hydrogen peroxide dosing pump is connected to the hydrogen peroxide inlet of the mixing tube; the water outlet of the mixing tube is connected to the inlet of the six-way valve through a pipeline; the acid injection tube is connected to the inlet of the acid injection pump, and the outlet of the acid injection pump is connected to the inlet of the six-way valve through a pipeline; the outlet of the six-way valve is connected to the inlet of the gas generating device through a pipeline, and the outlet of the gas generating device is connected to the inlet of the gas-liquid separation device; the air generating device is connected to the air inlet on the gas-liquid separation device through an airway; the water outlet on the gas-liquid separation device is connected to the waste liquid receiving device through a pipeline, and the gas outlet on the gas-liquid separation device is connected to the gas inlet of the gas drying device through the airway; the gas outlet of the gas drying device is connected to the gas inlet of the detection device through the airway, and the gas outlet of the detection device is connected to the waste gas absorption device through the airway.

[0008] Preferably, the material of the hydrogen peroxide dosing tube includes polyethylene, polypropylene and polyvinyl chloride.

[0009] Preferably, the inner diameter of the mixing tube is 2-3 mm and the length is 200-300 mm; the mixing tube winding frame is 80-120 mm long.

[0010] The method for using the sulfide detection device based on gas phase molecules comprises the following steps:

[0011] Step 1: The control system of the original sulfide detection device is provided with a gas phase molecular device controller built-in program. After the interference removal device is added, the gas phase molecular device controller built-in program is modified, and the modified control system controls the execution of steps 2 to 6;

[0012] Step 2, after the sulfide sample to be tested is shaken evenly, the sample is poured into the sample tube, the sample tube is placed in the automatic sampler, and the sample injection pump and the hydrogen peroxide dosing pump are started at the same time; the automatic sampler uniformly inhales the sample in the sample tube at a set flow rate, and the inhaled sample enters the mixing tube wound on the mixing tube winding frame through the sample injection pump; at the same time, the hydrogen peroxide dosing pump also inhales the hydrogen peroxide solution from the hydrogen peroxide dosing tube at a set flow rate, and the obtained hydrogen peroxide solution also enters the mixing tube wound on the mixing tube winding frame through the hydrogen peroxide dosing pump;

[0013] Step 3, mixing the sample and hydrogen peroxide in a mixing tube according to a set ratio, and removing reducing interfering substances in the sample in the mixing tube;

[0014] Step 4, the acid solution enters the six-way valve from the acid injection pump in the dosing device, and a certain amount of acid solution is added to the sample treated by the interference removal device. The six-way valve switches to control the sample and the acid solution to mix in the gas generating device, and the sample and the acid solution react to generate hydrogen sulfide gas and experimental waste liquid;

[0015] Step 5, using a gas-liquid separation device to separate the hydrogen sulfide gas discharged from the gas generating device and the experimental waste liquid, introducing a carrier gas from the air generating device, using a gas drying device to dry the hydrogen sulfide gas separated from the gas-liquid separation device, and the dried hydrogen sulfide gas enters the detection device; using a waste liquid receiving device to collect the experimental waste liquid separated from the gas-liquid separation device;

[0016] Step 6: Use a detection device to detect the optical absorption and intensity of hydrogen sulfide gas.

[0017] Preferably, in step 2, the sulfide sample to be tested is first flocculated with a zinc carbonate flocculant, filtered, and then the precipitate is washed with a zinc acetate-sodium acetate solution and then shaken evenly.

[0018] Preferably, the reducing interfering substance in step 3 includes sulfite.

[0019] Preferably, the acid solution in step 4 is a 5% phosphoric acid solution.

[0020] Preferably, the carrier gas introduced by the air generating device in step 5 includes nitrogen, argon and air.

[0021] Preferably, the carrier gas introduced by the air generating device in step 5 is air.

[0022] The beneficial effects of the present invention are as follows: in view of the problems that the pretreatment method for eliminating sulfite interference is complicated and difficult to control when the existing gas phase molecular spectrometer tests sulfide samples, the present invention designs a gas phase molecular spectrometer device for automatically eliminating interference in sulfide testing; the sulfide detection device based on gas phase molecules is suitable for various types of wastewater detection, and can efficiently and quickly reduce the positive interference of sulfite in sulfide detection; the sulfide detection device based on gas phase molecules is reliable and stable, and an interference elimination device can be added to the original gas phase molecular absorption spectrometer, which is easy to implement.

[0023] The original gas phase molecular system is equipped with a built-in program in the gas phase molecular equipment controller, which can automatically perform sulfide detection in water after running; while adding the interference removal device, the built-in program in the gas phase molecular equipment controller is also modified. The interference removal step is a step in the hydrogen sulfide detection program, which can automatically perform steps such as sampling, interference removal, detection, and data analysis; it eliminates the complicated procedures of manual pretreatment and the unstable errors, time-consuming and labor-intensive defects of manual operation, and realizes a gas phase molecular absorption spectrometer that can quickly, accurately and automatically eliminate the interference of sulfite in sulfide testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of a sulfide detection device based on gas phase molecules;

[0025] Figure 2 This is a diagram showing the effect of eliminating the interference of sulfite by directly adding masking agent.

[0026] Explanation of the accompanying drawings: automatic sampler 1, sample injection pump 2, interference removal device 3, hydrogen peroxide dosing tube 4, hydrogen peroxide dosing pump 5, mixing tube winding rack 6, dosing device 7, six-way valve 8, acid injection pump 9, acid injection tube 10, gas generating device 11, air generating device 12, gas-liquid separation device 13, waste liquid receiving device 14, gas drying device 15, detection device 16, waste gas absorption device 17. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0028] Embodiment 1

[0029] Experiments show that adding an appropriate amount of hydrogen peroxide directly to the sample to be tested can also completely eliminate the interference of sulfite, and has no obvious effect on the sulfide itself to be tested in the sample; the present invention adds an interference removal device on the basis of the original gas phase molecular spectrometer; Example 1 of the present application provides such Figure 1 Gas phase molecular based sulfide detection device with automated sulfite interference elimination for sulfide testing shown:

[0030] The sulfide detection device based on gas phase molecules is composed of a sampling device, a dosing device 7, a gas generating device 11, an air generating device 12, a gas-liquid separation device 13, a waste liquid receiving device 14, a gas drying device 15, a detection device 16 and a waste gas absorption device 17.

[0031] The sample injection device includes an automatic sample injector 1 and a sample injection pump 2. The automatic sample injector 1 is widely used as a supporting auxiliary device in the current commercial gas phase molecular instruments; the output end of the automatic sample injector 1 is connected to the sample injection pump 2 (peristaltic pump No. 1); the interference removal device 3 includes a hydrogen peroxide dosing tube 4, a hydrogen peroxide dosing pump 5 and a mixing tube winding rack 6; the dosing device 7 includes a six-way valve 8, an acid injection pump 9 and an acid injection tube 10;

[0032] The output end of the automatic sampler 1 is connected to the inlet of the sample injection pump 2, the outlet of the sample injection pump 2 is connected to the sample inlet of the mixing tube, the hydrogen peroxide dosing tube 4 is connected to the inlet of the hydrogen peroxide dosing pump 5, and the outlet of the hydrogen peroxide dosing pump 5 is connected to the hydrogen peroxide inlet of the mixing tube; the water outlet of the mixing tube is connected to the inlet of the six-way valve 8 through a pipeline; the acid injection tube 10 is connected to the inlet of the acid injection pump 9, and the outlet of the acid injection pump 9 is connected to the inlet of the six-way valve 8 through a pipeline; the outlet of the six-way valve 8 is connected to the inlet of the gas generating device 11 through a pipeline, and the outlet of the gas generating device 11 is connected to the inlet of the gas-liquid separation device 13; the air generating device 12 is connected to the air inlet of the gas-liquid separation device 13 through an airway; the water outlet on the gas-liquid separation device 13 is connected to the waste liquid receiving device 14 through a pipeline, and the gas outlet on the gas-liquid separation device 13 is connected to the gas inlet of the gas drying device 15 through the airway; the gas outlet of the gas drying device 15 is connected to the gas inlet of the detection device 16 through the airway, and the gas outlet of the detection device 16 is connected to the waste gas absorption device 17 through the airway.

[0033] Embodiment 2

[0034] Based on the first embodiment, the second embodiment of the present application provides an embodiment such as Figure 1 The method of using the sulfide detection device based on gas phase molecules is shown as follows:

[0035] After the sulfide sample to be tested is fixed with the zinc acetate-sodium acetate solution, it is shaken and poured into a sample tube of about 50 mL, and the sample tube is placed in an automatic sampler 1; the sample injection pump 2 and the hydrogen peroxide dosing pump 5 are started, and the automatic sampler 1 uniformly inhales the sample at a certain flow rate, for example, 20 mL / min, so as to achieve uniform injection of the experimental sample;

[0036] At the same time, the hydrogen peroxide dosing pump 5 also sucks hydrogen peroxide solution from the hydrogen peroxide dosing tube 4 at a certain flow rate; for example, 3% hydrogen peroxide is fed at a rate of 0.2 mL / min; the experimental sample and hydrogen peroxide are mixed in a certain proportion, and the hydrogen peroxide and the sample are fully mixed through the mixing tube winding frame (the mixing tube has an inner diameter of 2 to 3 mm, a length of 200 to 300 mm, and is orderly wound on a winding frame of 80 to 120 mm) under the driving force of the sample injection pump and the self-gravity of the sample wound in the mixing tube; reducing interfering substances such as sulfite in the experimental sample are removed;

[0037] 5% phosphoric acid solution enters the six-way valve from the acid sample pump 9 in the dosing device 7, and a certain amount of acid solution is added to the experimental sample treated by the interference removal device 3. The six-way valve switches to control a certain amount of sample and acid solution to mix and react. The gas generating device 11 is used to mix the experimental sample and the newly added acid solution, and the hydrogen sulfide gas and experimental waste liquid are generated by reaction in the gas generating device 11;

[0038] The reactants (hydrogen sulfide gas and experimental waste liquid) discharged from the gas generating device are separated by a gas-liquid separation device 13; a carrier gas is introduced from an air generating device 12, and a gas drying device 15 is used to dry the hydrogen sulfide gas separated from the gas-liquid separation device 13; the dried hydrogen sulfide gas enters a detection device 16 (light absorption tube), and a waste liquid receiving device 14 is used to collect the waste liquid separated from the gas-liquid separation device 13; the light absorption tube detects the optical absorption and intensity of the hydrogen sulfide gas, absorbs the monochromatic light of 202.6nm, and calculates the sulfide concentration according to the Lambert-Beer law; the carrier gas includes nitrogen, argon or air, and air has the best performance. The air generating device 12 is a supporting auxiliary equipment and is a standard configuration of commercially available gas phase analysis instruments.

[0039] The above steps are automatically performed according to the preset program. After setting the operating parameters, running "Sulfide Detection" can automatically perform sampling, adding hydrogen peroxide, adding phosphoric acid solution, gas drying, absorbance detection and analysis conversion without manual operation.

[0040] Embodiment 3

[0041] On the basis of Example 1 and Example 2, Example 2 of the present application provides a specific application of a sulfide detection device based on gas phase molecules in a coal-fired power plant:

[0042] In order to prove that directly adding hydrogen peroxide to the sample can eliminate the interference of sulfite, the experiment is designed as follows:

[0043] Prepare 50 mg / L sulfite (as SO3 2- Calculate) to a solution containing 1.121 mg / L sulfide. Take 14 portions of 50 mL of the solution to be tested, add 0.2 mL of hydrogen peroxide (3%) as a masking agent to 7 of them, set the interference elimination reaction time to 0 min, 2 min, 5 min, 10 min, 15 min, 20 min and 30 min in sequence, and do not add a masking agent to the other 7 portions. After eliminating the interference time of 0 min, 2 min, 5 min, 10 min, 15 min, 20 min and 30 min, test the sulfide concentration in sequence as a control group, and calculate the relative error of the detection.

[0044] The experimental results are as follows: When the 3% hydrogen peroxide masking agent is just added, the relative error of the test is still 5.4%, and the interference of sulfite is not completely removed. As the action time increases (2min to 30min), the relative error of the test is within ±1%, and it can be considered that the interference is completely eliminated. The elimination effect is shown in Figure 2. Figure 2 It can be seen that the masking effect of 3% hydrogen peroxide masking agent on sulfide determination is very fast and can maintain a stable masking effect within 2 minutes to 30 minutes. It provides a theoretical basis for the development of related devices and usage methods.

[0045] The desulfurization wastewater discharged by a coal-fired power plant has a high concentration of sulfite due to incomplete oxidation of the desulfurization system. The sulfite content is above 50 mg / L. Direct testing without eliminating sulfite will seriously interfere with sulfide detection. According to standard manual pretreatment, flocculation is performed with zinc carbonate flocculant, and after filtration, the precipitate is washed with zinc acetate-sodium acetate mixed washing liquid, and then 2 drops of 30% hydrogen peroxide are added to remove the interference of sulfite before measuring the sulfide concentration. The sulfide concentration test results of the five samples are: 1.32 mg / L, 1.56 mg / L, 0.81 mg / L, 2.10 mg / L, 1.15 mg / L;

[0046] The gas phase molecular absorption spectrometer was modified and a sulfite interference removal device was added. The device includes a hydrogen peroxide dosing tube, a hydrogen peroxide dosing pump and a mixing tube winding rack, which are connected to the sample tube for mixing with a three-way connector. The original gas phase molecular system has a program with sulfide detection function (a built-in program in the gas phase molecular device controller), which can automatically perform sulfide detection in water after running; while adding the interference removal device, the original detection program was also modified. The interference removal step is a step in the hydrogen sulfide detection program, which can automatically perform steps such as sampling, interference removal, detection, and data analysis. The hydrogen peroxide concentration used in the interference removal device is 3%, and the dosing rate of the hydrogen peroxide dosing pump is set to 0.2mL / min. The sulfide concentrations of the above five samples were detected using the detection device, and the results were 1.30mg / L, 1.53mg / L, 0.85mg / L, 2.15mg / L, and 1.16mg / L, respectively. The data deviations were 1.5%, 1.9%, 4.9%, 2.4% and 0.87%, respectively, all less than 10%. The results show that the gas-phase molecular sulfide detection device with automatic sulfite interference elimination function for sulfide testing is reasonably designed, the test results are accurate, and it has good applicability.

Claims

1. A sulfide detection device based on gas phase molecules, comprising a sampling device, a dosing device (7), a gas generating device (11), an air generating device (12), a gas-liquid separation device (13), a waste liquid receiving device (14), a gas drying device (15), a detection device (16) and a waste gas absorption device (17); characterized in that: The invention also comprises an interference removal device (3); the interference removal device (3) comprises a hydrogen peroxide dosing tube (4), a hydrogen peroxide dosing pump (5) and a mixing tube winding frame (6); a mixing tube is wound on the mixing tube winding frame (6); the injection device comprises an automatic injector (1) and a sample injection pump (2); the dosing device (7) comprises a six-way valve (8), an acid injection pump (9) and an acid injection tube (10); The output end of the automatic sampler (1) is connected to the inlet of the sample injection pump (2), the outlet of the sample injection pump (2) is connected to the sample inlet of the mixing tube, the hydrogen peroxide dosing tube (4) is connected to the inlet of the hydrogen peroxide dosing pump (5), and the outlet of the hydrogen peroxide dosing pump (5) is connected to the hydrogen peroxide inlet of the mixing tube; the water outlet of the mixing tube is connected to the inlet of the six-way valve (8) through a pipeline; the acid injection tube (10) is connected to the inlet of the acid injection pump (9), and the outlet of the acid injection pump (9) is connected to the inlet of the six-way valve (8) through a pipeline; the outlet of the six-way valve (8) is connected to the inlet of the gas generating device (11) through a pipeline, and the outlet of the gas generating device (11) is connected to the inlet of the gas-liquid separation device (13); the air generating device (12 ) is connected to the air inlet of the gas-liquid separation device (13) through an air passage; the water outlet of the gas-liquid separation device (13) is connected to the waste liquid receiving device (14) through a pipeline, and the gas outlet of the gas-liquid separation device (13) is connected to the gas inlet of the gas drying device (15) through the air passage; the gas outlet of the gas drying device (15) is connected to the gas inlet of the detection device (16) through the air passage, and the gas outlet of the detection device (16) is connected to the waste gas absorption device (17) through the air passage; the material of the hydrogen peroxide dosing pipe (4) includes polyethylene, polypropylene and polyvinyl chloride; the inner diameter of the mixing pipe is 2 to 3 mm and the length is 200 to 300 mm; the mixing pipe winding frame (6) is 80 to 120 mm long.

2. A method for using the sulfide detection device based on gas phase molecules as claimed in claim 1, characterized in that: The steps include: Step 1: The control system of the original sulfide detection device is provided with a gas phase molecular device controller built-in program. After the interference removal device (3) is added, the gas phase molecular device controller built-in program is modified, and the modified control system controls the execution of steps 2 to 6; Step 2, after the sulfide sample to be tested is shaken evenly, the sample is poured into a sample tube, the sample tube is placed in an automatic sampler (1), and the sample injection pump (2) and the hydrogen peroxide dosing pump (5) are started at the same time; the automatic sampler (1) uniformly sucks the sample in the sample tube at a set flow rate, and the sucked sample enters the mixing tube wound on the mixing tube winding frame (6) through the sample injection pump (2); at the same time, the hydrogen peroxide dosing pump (5) also sucks the hydrogen peroxide solution from the hydrogen peroxide dosing tube (4) at a set flow rate, and the obtained hydrogen peroxide solution also enters the mixing tube wound on the mixing tube winding frame (6) through the hydrogen peroxide dosing pump (5); Step 3, mixing the sample and hydrogen peroxide in a mixing tube according to a set ratio, and removing reducing interfering substances in the sample in the mixing tube; Step 4, the acid solution enters the six-way valve (8) from the acid sample pump (9) in the dosing device (7), and a certain amount of the acid solution is added to the sample treated by the interference removal device (3). The six-way valve (8) switches to control the sample and the acid solution to mix in the gas generating device (11), and the sample and the acid solution react to generate hydrogen sulfide gas and experimental waste liquid; Step 5, using a gas-liquid separation device (13) to separate the hydrogen sulfide gas and the experimental waste liquid discharged from the gas generating device (11), introducing a carrier gas from the air generating device (12), using a gas drying device (15) to dry the hydrogen sulfide gas separated from the gas-liquid separation device (13), and the dried hydrogen sulfide gas enters the detection device (16); using a waste liquid receiving device (14) to collect the experimental waste liquid separated from the gas-liquid separation device (13); Step 6: Use the detection device (16) to detect the optical absorption and intensity of hydrogen sulfide gas.

3. The method for using the sulfide detection device based on gas phase molecules according to claim 2, characterized in that: In step 2, the sulfide sample to be tested is first flocculated with a zinc carbonate flocculant, filtered, and then washed with a zinc acetate-sodium acetate solution and then shaken.

4. The method for using the sulfide detection device based on gas phase molecules according to claim 2, characterized in that: The reducing interfering substance in step 3 includes sulfite.

5. The method for using the gas phase molecule based sulfide detection device according to claim 2, characterized in that: The acid solution in step 4 is a 5% phosphoric acid solution.

6. The method for using the gas phase molecule based sulfide detection device according to claim 2, characterized in that: The carrier gas introduced from the air generating device (12) in step 5 includes nitrogen, argon and air.

7. The method for using the gas phase molecule based sulfide detection device according to claim 2, characterized in that: In step 5, the carrier gas introduced by the air generating device (12) is air.

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