Search result: HJ 688-2019 (HJ 688-2013 Older version)
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Stationary source emission--Determination of hydrogen fluoride--Ion chromatography
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HJ 688-2019
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| HJ 688-2013 | English | 439 |
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Stationary source emission. Determination of hydrogen fluoride. Ion chromatography
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HJ 688-2013
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| Standard ID | HJ 688-2019 (HJ688-2019) | | Description (Translated English) | Stationary source emission--Determination of hydrogen fluoride--Ion chromatography | | Sector / Industry | Environmental Protection Industry Standard | | Classification of Chinese Standard | Z15 | | Classification of International Standard | 13.040.40 | | Word Count Estimation | 12,165 | | Date of Issue | 2019 | | Date of Implementation | 2020-06-30 |
HJ 688-2019
Stationary source emission--Determination of hydrogen fluoride--Ion chromatography
National Environmental Protection Standard of the People's Republic of China
Replaces HJ 688-2013
Determination of hydrogen fluoride in exhaust gas from stationary pollution sources
Ion chromatography
Stationary source emission-Determination of hydrogen fluoride
-Ion chromatography
2019-12-31 released
2020-06-30 implementation
Released by the Ministry of Ecology and Environment
i table of contents
Foreword ... ii
1 Scope ... 1
2 Normative references ... 1
3 Terms and definitions ... 1
4 Methodology ... 1
5 Interference and cancellation ... 2
6 Reagents and materials ... 2
7 Instruments and equipment ... 2
8 Sample ... 3
9 Analysis steps ... 5
10 Calculation and Representation of Results ... 6
11 Precision and accuracy ... 7
12 Quality Assurance and Quality Control ... 7
13 Waste disposal ... 8
14 Notes ... 8
Foreword
In order to implement the "Environmental Protection Law of the People's Republic of China"
Environment, protect human health, standardize the determination method of hydrogen fluoride in exhaust gas from fixed pollution sources, and formulate this standard.
This standard specifies ion chromatography for the determination of hydrogen fluoride in exhaust gas from stationary sources.
This standard is for the determination of hydrogen fluoride in exhaust gas from stationary sources by ion chromatography (Interim) (HJ 688-2013)
Revision.
This standard was first published in.2013. The original drafting unit was Dongying City Environmental Monitoring Station. This is the first revision.
The main contents of the amendment are as follows.
-The scope of application was modified, and the method detection limit and determination lower limit were changed;
-Revised normative references;
-Improved sample collection, processing and storage methods;
-Refine the chromatographic reference conditions and increase the ion chromatogram of the target component;
-Revised the result expression formula and result expression requirements;
-Improved the terms of quality assurance and quality control and precautions;
-Added warnings, terms and definitions, interference and elimination, precision and accuracy clauses.
From the date of implementation of this standard, the original standard "Determination of hydrogen fluoride in stationary pollution sources by ion chromatography (interim)"
(HJ 688-2013) Repealed.
This standard is formulated by the Department of Eco-Environmental Monitoring, Laws and Standards Department of the Ministry of Ecology and Environment.
This standard was drafted. Shandong Dongying Ecological Environment Monitoring Center, China University of Petroleum (East China).
Verification units of this standard. Shandong Ecological Environment Monitoring Center, Shandong Tai'an Ecological Environment Monitoring Center, Shandong Province
Bo Ecological Environment Monitoring Center, Shandong Weifang Ecological Environment Monitoring Center, China University of Petroleum (East China) Dongying Zhongshi University
Petroleum and Petrochemical Testing and Evaluation Center and Qingdao Institute of Bioenergy and Process, Chinese Academy of Sciences.
This standard was approved by the Ministry of Ecology and Environment on December 31,.2019.
This standard will be implemented from June 30, 2020.
This standard is explained by the Ministry of Ecology and Environment.
1 Determination of hydrogen fluoride in exhaust gas from stationary sources Ion chromatography
Warning. Hydrogen fluoride is harmful to the human body. Take precautions when taking samples to avoid inhalation or contact with skin and eyes. Make use of
The sodium hydroxide and potassium hydroxide used are strongly corrosive. Reagent preparation and sample preparation should avoid contact with skin and
Clothing.
1 Scope
This standard specifies ion chromatography for the determination of hydrogen fluoride in exhaust gas from stationary sources.
This standard applies to the determination of hydrogen fluoride in exhaust gas from stationary pollution sources.
When the sampling volume is 20 L (standard state) and the constant volume is 100 ml, the method detection limit is 0.08 mg/m3.
The lower limit of determination is 0.32 mg/m3.
2 Normative references
This standard refers to the following documents or clauses therein. For undated references, the valid version applies to this
standard.
GB/T 16157 Determination of particulate matter and sampling of gaseous pollutants in exhaust from stationary pollution sources
HJ/T 47 Technical Specifications of Flue Gas Sampler
HJ/T 48 Soot Sampler Technical Specifications
HJ/T 397 Fixed source exhaust gas monitoring technical specifications
3 terms and definitions
The following terms and definitions apply to this standard.
3.1
Hydrogen fluoride
The hydrogen fluoride measured in this standard refers to inorganic fluorides such as hydrogen fluoride and silicon tetrafluoride (as fluorine
Hydrogen meter).
4 Method principle
The heated sampling tube is used to collect the exhaust gas sample, and the particulate matter, gaseous hydrogen fluoride and gasified hydrogen fluoride are removed by a filtering membrane.
The droplets are absorbed by the alkaline absorbent to generate fluoride ions. The sample is injected into the ion chromatograph for separation and detection.
Quantitatively, peak area or peak height.
25 Interference and cancellation
5.1 Particulate fluoride interferes with the measurement. Use a filter to remove it during sampling.
5.2 Acetate ions interfere with the determination of fluoride. You can adjust the eluent concentration and flow rate, and replace the high-efficiency special chromatography.
Column and other methods to eliminate and reduce its interference.
6 Reagents and materials
Unless otherwise stated, all analytical reagents in accordance with national standards are used in the analysis. The resistivity of experimental water is ≥
18 MΩ · cm deionized water.
6.1 Potassium hydroxide (KOH). excellent grade pure.
6.2 Sodium hydroxide (NaOH). excellent grade pure.
6.3 Sodium carbonate (Na2CO3). Excellent grade. It should be dried at 105 ° C ± 5 ° C and constant weight before use and stored in a desiccator.
6.4 Sodium bicarbonate (NaHCO3). Excellent grade. It should be placed in a desiccator for 24 h before use.
6.5 Sodium fluoride (NaF). Excellent grade. It should be dried at 105 ° C ± 5 ° C before use and kept in a desiccator.
6.6 Aqueous solution absorption solution. c (KOH) = 30 mmol/L or c (NaOH) = 30 mmol/L.
Weigh 1.68 g of potassium hydroxide (6.1) or 1.20 g of sodium hydroxide (6.2), dissolve in an appropriate amount of water and transfer to 1000 ml
In a volumetric flask, dilute to volume with water, mix well, and transfer to a polyethylene bottle. Provisional use.
6.7 Eluent. Prepare according to the instrument model and the operating conditions of the column manual. The eluent conditions given below are provided
reference.
6.7.1 Carbonate eluent. c (Na2CO3) = 3.2 mmol/L, c (NaHCO3) = 1.0 mmol/L.
Accurately weigh 0.6784 g of sodium carbonate (6.3) and 0.1680 g of sodium bicarbonate (6.4), respectively, and dissolve them in an appropriate amount of water.
Transfer the volume to a.2000 ml volumetric flask, dilute to volume with water, and mix.
6.7.2 Hydroxide eluent. Generated by the eluent automatic electrolytic generator online.
Note. The eluent should be degassed before use to prevent air bubbles from entering the ion chromatography system.
6.8 Fluoride stock solution. ρ (F-) = 500 mg/L.
Accurately weigh 1.1053 g of sodium fluoride (6.5), dissolve it in an appropriate amount of water, transfer it to a 1000 ml volumetric flask, and dilute with water
Make up to volume, mix well, transfer to a polyethylene bottle, and refrigerate at 4 ° C for a month.
They can also be formulated using certified standard solutions.
6.9 Fluoride standard solution. ρ (F-) = 50 mg/L.
Pipette 10.00 ml of sodium fluoride stock solution (6.8), transfer to a 100 ml volumetric flask, dilute to volume with water, mix well,
Store at room temperature for 14 days.
6.10 Filter membrane. Teflon material, the retention efficiency for particles larger than 0.3 μm is not less than 99.9%.
7 instruments and equipment
7.1 Constant temperature heating sampling tube
A filter membrane (6.10) is installed at the end of the constant temperature heating sampling tube. The heating temperature is 120 ° C ± 5 ° C and the temperature control accuracy is 1 ° C. Sampling tube
3 is made of polytetrafluoroethylene or titanium alloy, and the inner surface is smooth.
7.2 Flue gas sampler
The flue gas sampler shall meet the technical requirements of HJ/T 47.
7.3 Smoke Sampler
The dust sampler should meet the technical requirements of HJ/T 48 and be equipped with a flow controllable shunt device.
7.4 Absorption bottle. 75 ml bubble absorption bottle made of PTFE, polyethylene or polypropylene.
7.5 Connection tube. PTFE hose or silicone rubber tube lined with PTFE film should be as short as possible.
7.6 Membrane clip. PTFE material, the size matches the filter membrane (6.10).
7.7 Cooling device. Use ice-water bath or other device whose temperature does not exceed 5 ℃.
7.8 Ion chromatograph. An analysis system consisting of an ion chromatograph host, operating software, and required accessories. Equipped with anion
Off-column (polydivinylbenzene/ethylvinylbenzene/polyvinyl alcohol matrix, with alkanol quaternary ammonium or alkyl quaternary ammonium functional group, hydrophilic,
High-capacity chromatography columns), anion guard columns, and conductivity detectors are suitable for the detection of fluoride ions.
7.9 Disposable water-based microfiltration membrane syringe filter. 0.45 µm pore size.
7.10 Syringe. 10 ml.
7.11 Instruments and equipment commonly used in general laboratories.
8 samples
8.1 Sample collection
8.1.1 Exhaust gas samples from stationary sources
The location and sampling of exhaust gas from fixed pollution sources shall comply with the relevant regulations in GB/T 16157 and HJ/T 397. For sampling devices, see
figure 1. During the sampling process, the temperature of the sampling tube and filter should be maintained at ≥120 ° C to avoid condensation of water vapor before the absorption bottle.
Figure 1 Schematic diagram of sampling device for hydrogen fluoride in exhaust gas from stationary pollution sources
Fig. 2 Schematic diagram of sampling device for hydrogen fluoride in exhaust gas from stationary pollution source (when it contains droplets)
After the sampling tube (7.1), two 75 ml bubble absorption bottles (7.4) each containing 50 ml of absorption liquid (6.6) are connected in series, and
The flue gas sampler (7.2) is connected. According to the gaseous pollutant collection method, the flow rate is 0.5 L/min ～ 1.0 L/min within 1 hour
3 to 4 samples are taken at equal time intervals or samples are collected continuously for 1 hour. It can also be based on the actual concentration of the sample in the exhaust gas.
Degree, appropriately extend or shorten the sampling time.
Note. When the moisture content in the exhaust gas from the fixed pollution source is relatively large, and the moisture absorption of hydrogen fluoride exists in the form of mist droplets, the layout and sampling should comply with GB/T
The provisions of 16157 and HJ/T 397 on the collection methods of particulate matter, the sampling device is shown in Figure 2. Two tubes in series after the sampling tube (7.1)
75 ml bubble absorption bottles (7.4) each containing 50 ml of absorption solution (6.6), connected to the smoke sampler (7.3), collected according to the particulate matter
Set method to collect gas samples. Through the diverter valve, control the sampling flow rate of hydrogen fluoride gas from 0.5 L/min to 1.0 L/min, at 1
Sampling 3 to 4 samples at equal intervals within one hour or continuous 1 hour sampling.
8.1.2 Blanks throughout the program
Each batch of samples should bring at least a set of full-process blank samples, and bring the absorption bottle filled with the absorption liquid to the sampling site.
It is not connected to the sampler and will be taken back to the laboratory for testing after the sampling is completed.
8.2 Sample transport and storage
After the sample was collected, the absorption bottle was sealed with a connecting tube (7.5), and stored at room temperature. The analysis and measurement were completed within 24 hours. If not
During analysis, the sample should be transferred to a polyethylene bottle, which can be stored at room temperature for 14 days.
8.3 Preparation of test specimens
8.3.1 Exhaust gas samples from stationary sources
Transfer the sample solution (8.1.1 and 8.1.2) from the two absorption bottles into two 100 ml stoppered colorimetric tubes.
Measure the water to wash the absorption bottle and the inner wall of the connecting tube.
58.3.2 Laboratory blank sample
In the laboratory, take the same batch of absorbent bottles with the same volume of absorbent solution and prepare the laboratory empty according to the same steps in 8.3.1.
White sample.
9 Analysis steps
9.1 Chromatographic Reference Conditions
Optimize the measurement conditions or parameters according to the instrument model and configuration, and optimize the eluent concentration
degree.
Reference condition 1. eluent is 30 mmol/L potassium hydroxide solution, flow rate is 1.20 ml/min, injection volume is 25 µl,
The column temperature was 30 ° C and the suppressor current was 90 mA.
Reference condition 2. The eluent is a mixed solution of 3.2 mmol/L sodium carbonate and 1.0 mmol/L sodium bicarbonate, and the flow rate is
0.40 ml/min, injection volume is 20 µl, and column temperature is 25 ° C.
9.2 Standard curve establishment
Remove 0 ml, 0.10 ml, 0.20 ml, 0.50 ml, 1.00 ml, 2.00 ml, 5.00 ml of fluoride standard
Place the solution (6.9) in a set of 50 ml volumetric flasks, make up to volume with water, and shake well. Fluoride ion concentration in the standard series
(Calculated as F-) 0.00 mg/L, 0.10 mg/L, 0.20 mg/L, 0.50 mg/L, 1.00 mg/L, 2.00 mg/L and
5.00 mg/L. The appropriate standard series concentration range can be determined based on the concentration of the sample being measured. Standards of different concentrations
The solution is injected into the ion chromatograph, and the response value and retention time of the instrument are measured. With fluoride ion concentration (calculated as F-, mg/L) as the horizontal
Coordinate, peak area or peak height is the ordinate, and a standard curve is established. The fluoride ion chromatogram in the hydroxide eluent system is shown in Figure 3.
The fluoride ion chromatogram in the carbonate eluent system is shown in Figure 4.
1-fluoride ion; 2-chloride ion; 3-sulfate ion; 4-bromide ion; 5-nitrate ion.
Figure 3 Chromatogram of fluoride standard ion (hydroxide eluent system)
61-fluoride ion; 2-chloride ion; 3-bromide ion; 4-nitrate ion; 5-sulfate ion.
Figure 4 Chromatogram of fluoride standard ion (carbonate eluent system)
9.3 Sample measurement
The prepared samples (8.3.1 and 8.3.2) are filtered with a disposable water-based microporous membrane syringe filter (7.9) and then injected.
The injector (7.10) is injected into the ion chromatograph, and the same chromatographic reference conditions (9.1) are used to establish the standard curve as the sample.
Determination. When the F-content in the sample exceeds the concentration range of the standard curve, it shall be determined after dilution with water.
10 Calculation and representation of results
10.1 Calculation of results
The concentration of hydrogen fluoride in the exhaust gas from the stationary pollution source is calculated according to formula (1).
0.19
0.20100) (2211
) (
nd
HF V
DD (1)
Where. ρ (HF)-the concentration of HF in the exhaust gas from a fixed pollution source, mg/m3;
ρ1--F after dilution of the first colorimetric tube sample detected from the standard curve
-Concentration, mg/L;
ρ2--F after dilution of the second colorimetric tube sample detected from the standard curve
-Concentration, mg/L;
Vnd--Sampling volume of dry flue gas under standard conditions (273.15K, 1013.25hPa), L;
Molar mass of 20.0--HF, g/mol;
Molar mass of 19.0--F-, g/mol;
100--constant volume, ml;
D1--the dilution factor of the first colorimetric tube sample;
D2--The dilution factor of the second colorimetric tube sample.
Note. If ρ2 is lower than the detection limit of the method, ρ2 is counted as zero.
10.2 Results representation
7 The number of reserved digits after the decimal point of the measurement result is consistent with the detection limit, and a maximum of three significant digits are retained.
11 Precision and accuracy
11.1 Precision
Six verification laboratories added blank spiked concentrations of 0.20 mg/L, 2.00 mg/L, and 8.00 mg/L, respectively.
Six parallel determinations of the standard sample after the sampling process.
Relative standard deviations in the laboratory are. 1.1% to 11%, 0.8% to 6.0%, 0.3% to 2.5%;
The relative standard deviations between laboratories were. 7.1%, 2.3%, and 1.8%;
Repeatability limits are. 0.11 mg/m3, 0.54 mg/m3, and 0.92 mg/m3;
Reproducibility limits were. 0.15 mg/m3, 0.65 mg/m3, and 1.4 mg/m3.
Six verification laboratories simulated actual samples of 0.50 mg/m3 and 10.0 mg/m3 hydrogen fluoride standard gases, respectively.
Perform 6 parallel determinations.
The relative standard deviations in the laboratory are. 2.3% to 7.6% and 1.9% to 4.0%;
The relative standard deviations between the laboratories are 4.2% and 2.7%;
Repeatability limits are. 0.10 mg/m3 and 0.82 mg/m3;
Reproducibility limits were 0.12 mg/m3 and 1.1 mg/m3, respectively.
11.2 Accuracy
Six verification laboratories have performed a unified standard sample (standard value of 1.53 mg/L ± 0.06) containing fluoride (calculated as F-)
mg/L) 6 parallel determinations.
The relative errors are. -3.3% to 1.5%;
The final relative error is -1.0% ± 3.6%.
Six verification laboratories simulated the sampling process of solutions containing 10.0 μg, 50.0 μg, and.200 μg of fluoride ions
After recovery measurement.
Spike recovery rates were 88.8% ～ 111%, 92.4% ～ 112%, 96.3% ～ 106%;
The final recoveries were spiked at 101% ± 17.5%, 103% ± 14.4%, and 101% ± 6.6%.
12 Quality Assurance and Quality Control
12.1 Blank test
At least one full program blank and one experiment per 20 samples or each batch (less than 20 samples/batch)
Room is blank. The blank measurement value should be lower than the detection limit of the method, otherwise the cause should be found or the sample should be collected again.
12.2 Calibration curve
When making the standard curve, there should be at least six concentration points including the zero concentration point, and the linear correlation coefficient of the standard curve should be
Should be ≥0.995. For every 20 samples or each batch (less than 20 samples/batch), the middle concentration point of the standard curve should be used.
Check the relative error should be within ± 10%. Otherwise, find the cause or re-establish the standard curve.
812.3 Penetration
The content of hydrogen fluoride in the second absorption bottle should be less than 10% of the total hydrogen fluoride sample, otherwise the sample should be collected again. press
Calculate the transmittance of the second absorption bottle according to formula (2).
100%
22
DD
K
(2)
In the formula. K--penetration of the second absorption bottle;
ρ1--F after dilution of the first colorimetric tube sample detected from the standard curve
-Concentration, mg/L;
ρ2--F after dilution of the second colorimetric tube sample detected from the standard curve
-Concentration, mg/L;
100--constant volume, ml; D1--the dilution factor of the first colorimetric tube sample;
D2--The dilution factor of the second colorimetric tube sample.
13 Waste treatment
The waste liquid and waste generated in the experiment should be collected separately and properly stored, safely processed as required or entrusted to a qualified unit
For processing.
14 Notes
14.1 Titanium alloy is chemically inert, has a smooth surface, and is resistant to corrosion. It can be used at temperatures between 450 ° C and 550 ° C. Teflon
The use temperature of ethylene must not be higher than 250 ° C, otherwise it will decompose and release fluoride. New PTFE devices may release fluorine
The compound gas needs to be heated in advance at the sampling temperature.
14.2 The connecting tube between the filter holder and the absorption bottle should be as short as possible, and the airtightness of the system should be checked.
14.3 The connection tube between the filter holder and the absorption bottle is kept in a gentle downward manner to prevent water vapor in the sample gas from cooling in the connection tube.
After coagulation, it was returned to the filter holder.
14.4 After the analysis of each sample, the eluent should be used to clean the instrument pipeline.
14.5 This method has high sensitivity. The absorption bottle, connection tube and utensils should be washed carefully. Prevent the residual fluorination of utensils during operation
Interference from chemicals, tap water and air.
......
HJ 688-2013
Stationary source emission.Determination of hydrogen fluoride.Ion chromatography
National Environmental Protection Standard of the People's Republic
Determination of hydrogen fluoride in fixed pollution source
Ion chromatography (interim)
Stationary source emission-Determination of hydrogen fluoride-
Ion chromatography
Published on.2013-12-26
2014-03-01 Implementation
Ministry of Environmental Protection released
Content
Preface II
1 Scope 1
2 Normative references 1
3 Principle of the method 1
4 reagents and materials..1
5 instruments and equipment..2
6 samples.3
7 Analysis step 4
8 Calculation and representation of results 5
9 Quality Assurance and Quality Control.5
10 Waste treatment.5
11 Notes.5
Foreword
To implement the Environmental Protection Law of the People's Republic of China and the Law of the People's Republic of China on the Prevention and Control of Atmospheric Pollution
This standard is formulated to ensure human health and to regulate the monitoring methods of hydrogen fluoride in fixed source waste gas.
This standard specifies ion chromatography for the determination of hydrogen fluoride in fixed source exhaust gases.
This standard is the first release.
This standard was formulated by the Science and Technology Standards Department of the Ministry of Environmental Protection.
This standard is mainly drafted by. Dongying Environmental Monitoring Station.
This standard was approved by the Ministry of Environmental Protection on December 26,.2013.
This standard has been implemented since March 1,.2014.
This standard is explained by the Ministry of Environmental Protection.
Determination of Hydrogen Fluoride from Fixed Pollution Sources by Ion Chromatography (Provisional)
1 Scope of application
This standard specifies ion chromatography for the determination of hydrogen fluoride in fixed source exhaust gases.
This standard is applicable to the determination of gaseous fluoride in fixed pollution source exhaust gas. It is expressed as hydrogen fluoride concentration and cannot be used to determine fluorocarbon.
Compounds such as Freon.
When the sampling volume is 120L and the volume is.200ml, the detection limit is 0.03mg/m3, and the lower limit of determination is 0.12mg/m3;
When the volume is 500 ml, the detection limit is 0.08 mg/m3, and the lower limit of determination is 0.32 mg/m3.
2 Normative references
The contents of this standard refer to the following documents or their terms. For dated references, only the dated version
Applicable to this standard. For undated references, the latest edition applies to this standard.
GB/T 6682 Analytical laboratory water specifications and test methods
HJ/T 47 flue gas sampler technical conditions
HJ/T 48 soot sampler technical conditions
HJ/T 365 Hazardous Waste (including Medical Waste) Incineration and Disposal Facilities Dioxin Emission Monitoring Technical Specifications
HJ/T 397 Fixed Source Exhaust Gas Monitoring Technical Specification
3 Principle of the method
The method adopts a heated sampling tube to continuously collect exhaust gas samples from a fixed pollution source, and filters the particles through a heated filter.
The exhaust gas sample enters the cooled alkaline absorption liquid, and the gaseous fluoride is absorbed to generate fluorine ions. Separation by ion chromatography
Measurement, retention time qualitative, response value quantification.
4 reagents and materials
Unless otherwise stated, analytically pure reagents in accordance with national standards were used for the analysis; water, GB/T 6682, Level 2.
4.1 Potassium hydroxide (KOH).
4.2 Anhydrous sodium carbonate (Na2CO3).
4.3 Sodium fluoride (NaF), pure grade. dried at 110 ° C for 2 h, stored in a desiccator.
4.4 Absorbent
4.4.1 Potassium hydroxide solution. c(KOH) = 0.1 mol/L.
Weigh 5.6 g of potassium hydroxide (4.1), dissolve in water, and dilute to 1000 ml.
4.4.2 Potassium hydroxide-sodium carbonate solution. c(KOH) = 0.006 mol/L, c(Na2CO3) = 0.008 mol/L.
0.33 g of potassium hydroxide (4.1) and 0.85 g of anhydrous sodium carbonate (4.2) were weighed, dissolved in water, and diluted to 1000 ml.
4.5 Eluent
4.5.1 Potassium hydroxide solution. c(KOH) = 0.030 mol/L.
1.7 g of potassium hydroxide (4.1) was weighed, dissolved in water, and diluted to 1000 ml.
4.5.2 Potassium hydroxide-sodium carbonate solution. c(KOH) = 0.0018 mol/L, c(Na2CO3) = 0.0024 mol/L.
0.1 g of potassium hydroxide (4.1) and 0.26 g of anhydrous sodium carbonate (4.2) were weighed, dissolved in water, and diluted to 1000 ml.
4.6 Standard storage solution of sodium fluoride. ρ(F-) = 500μg/ml.
Weigh 0.1105g of sodium fluoride (4.3) dissolved in water, transfer it to a 100ml volumetric flask, dilute with water to the mark, shake
Store well in a polyethylene bottle and store at 4 ° C for one month. Remove it and use it at room temperature for use. Can also use certified
Standard solution is prepared.
4.7 Standard use solution of sodium fluoride. ρ(F-) = 5μg/ml.
Pipette 1.00ml of sodium fluoride standard stock solution (4.6), transfer to a 100ml volumetric flask, and dilute with eluent (4.5)
To the marking line, shake it, and use it now.
4.8 Microporous membrane. 0.45μm pore size, made of acetate or polytetrafluoroethylene (PTFE).
5 Instruments and equipment
5.1 Glass measuring device
Unless otherwise stated, the national standard Class A glass gauge was used for the analysis.
5.2 Flue gas sampler
The flue gas sampler should meet the technical requirements of HJ/T 47, consisting of sampling tube, filter unit, absorption unit, dryer, and cold.
But the device, flow meter and control device and pump are composed, see Figure 1. The pump should ensure sufficient pumping capacity.
When the load resistance of the sample system is 20 kPa, the pumping flow rate of the pump should not be lower than 2.0 L/min.
1. Sampling tube; 2. Filter; 3, 4. Stop valve; 5, 6. Small porous glass plate absorption bottle for main road; 7, 8. Small porous glass plate absorption bottle for bypass;
9. Dryer; 10. Pressure sensor; 11. Temperature sensor; 12. Flow sensor; 13. Flow regulating device; 14. Air pump; 15. Flue wall;
16. Inside the dotted line is the heating zone. 17. Ice water bath or a temperature controlled cooling device.
Fig.1 Schematic diagram of hydrogen fluoride constant flow sampling device in exhaust gas
5.3 Constant velocity sampling smoke sampler
The smoke sampler should be used as a constant velocity sampled flue gas sampler and should meet the technical requirements of HJ/T 48. Sampler
Sample tube, filter device, absorption unit, dryer, cooling device, flow metering and control device, and air pump, see
figure 2. Also refer to the instrument recommended in HJ/T 365.
1. Thermocouple or RTD thermometer; 2. Pitot tube; 3. Combined sampling tube (including filter); 4, 5. Large impact absorption bottle; 6. Empty bottle; 7. Dry
8. Micro pressure sensor; 9. Pressure sensor; 10. Temperature sensor; 11. Flow sensor; 12. Micro processing system; 13. Micro printer or interface;
14. Display; 15. Flow regulating device; 16. Ice water bath or temperature controlled cooling device; 17. Air pump; 18. Flue wall;
19. Inside the dotted line is the heating zone.
Fig. 2 Schematic diagram of isothermal sampling device for hydrogen fluoride in exhaust gas
5.4 Sampling nozzle. The material is borosilicate glass, quartz glass or titanium alloy, which should meet the requirements of HJ/T 48.
5.5 Sampling pipe liner. made of PTFE, borosilicate glass, quartz glass or titanium alloy, the inner surface of the inner liner shall be
Smooth and smooth.
5.6 Filter. Material made of quartz glass fiber, PTFE filter cartridge, filter or titanium alloy sintered filter;
The retention efficiency of the particles larger than 0.5 μm is more than 99.9%.
5.7 Filter holder. Made of PTFE, borosilicate glass or quartz glass, the size matches the filter (5.6).
It should be easy to pick and place, and the interface is well sealed.
5.8 Absorbent bottle. 50ml small porous glass plate absorption bottle or 250ml large punch made of borosilicate glass or quartz glass
Hit the absorption bottle.
5.9 connecting pipe. the connecting pipe between the sampling pipe outlet and the absorption bottle, between the absorption bottles, and between the absorption bottle and the dryer is PTFE,
Polypropylene, polyethylene or fluoro rubber tubes should be as short as possible.
5.10 Cooling device. The cooling device adopts an ice water bath or other devices that control the temperature not exceeding 5 °C.
5.11 Liquid storage bottle. Polyethylene plastic bottle with a capacity of 500ml.
5.12 Ion Chromatograph. Contains a conductivity detector and an anion column and an anion guard column.
5.13 Common instruments in the laboratory.
6 samples
The sampling position, sampling point, number of sampling points, and sampling frequency are performed in accordance with the relevant provisions in HJ/T 397.
Exhaust gas sampling is divided into constant current sampling and isokinetic sampling when droplets are present in the exhaust gas. Temperature control of sampling tube and filter device
The system is in the range of 185oC ± 5oC.
6.1 Sample Collection
6.1.1 Constant current sampling. 2 sets of 30ml absorption liquid (4.4.1 or 4.4.2) are respectively connected in series on the main path and bypass of the sampling device.
Small porous glass plate absorption bottle (5.8). Connect the sampling tube to the absorption bottle and the absorption bottle and dryer with a connecting tube (5.9).
With a flow rate of 2.0L/min, the sampling time of each sample is 20min~60min. After sampling, remove the connecting tube and the absorption bottle together.
Seal the absorption bottle with a connecting tube.
6.1.2 Constant speed sampling. 3 large shock absorption bottles (5.8) are connected in series on the sampling device, between the sampling tube and the absorption bottle and sucked
Connect the bottles with a connecting tube (5.9). The first two absorption bottles are each filled with 75ml of absorbent (4.4.1 or 4.4.2), the third
The bottle is empty and connected to the dryer to collect the exhaust gas sample at a rate of 90%~110%. The sampling time principle of each sample
Not less than 20min. After sampling, the connecting tube and the absorption bottle are removed together, and the absorption bottle is sealed with a connecting tube.
Note. Particles collected by the filter are not analyzed.
6.2 Sample transportation and preservation
The absorption bottle is transported vertically in a clean container. The laboratory was stored at room temperature for no more than one week.
6.3 Sample preparation
6.3.1 Sample I
When sampling according to 6.1.1, transfer the absorption liquid from the main absorption bottle to a.200ml volumetric flask.
The absorption bottle and the connecting tube were separately washed with an appropriate amount of water, and the washing liquid was combined into the above-mentioned volumetric flask. Repeat this operation 3
Times.
Dilute to the mark with water. The sample was filtered through a 0.45 μm microporous membrane (4.8) to obtain a sample solution, which was transferred to a stock solution.
Bottle (5.11).
6.3.2 Sample II
When sampling according to 6.1.2, except for transferring the absorption liquid in the large impact absorption bottle to the 500ml volumetric flask, the rest of the operation is the same.
6.3.1.
6.4 blank sample
Prepare 2 sets of sealed absorption bottles with the same amount of absorbent required for actual sampling, and bring them to the sampling location.
The sample is connected and brought back to the laboratory after sampling. According to the procedure of 6.3, a blank sample of the whole program is obtained.
7 Analysis steps
7.1 Chromatographic conditions
Refer to the instrument manual for selection.
7.2 Drawing of standard curve
Take 6 50ml colorimetric tubes and prepare a standard series according to Table 1.
Table 1 sodium fluoride standard series
Pipe number 0 1 2 3 4 5
NaF standard use solution (ml) 0 2.00 5.00 10.0 20.0 50.0
Eluent (ml) 50.0 48.0 45.0 40.0 30.0 0
F-concentration (μg/ml) 0 0.20 0.50 1.00 2.00 5.00
After mixing evenly, different concentrations of standard solution are injected into the ion chromatograph from low to high, respectively, and the response value of the measuring instrument is measured.
And retention time. A standard curve is drawn from the instrument response to the fluoride ion concentration.
7.3 Determination of samples
The sample was injected into the ion chromatograph to determine the fluoride ion concentration under the same conditions as the standard curve.
Qualitative, the instrument response is quantified.
7.4 Blank determination
In addition to the full program blank sample injected into the ion chromatograph, the rest of the same sample was measured.
8 Calculation and representation of results
8.1 Calculation of results
The concentration of hydrogen fluoride in the fixed source exhaust gas is calculated by the following formula.
0.19
0.20)( 0s ××−=
ndV
HF
Ρρρ )(
Where. ρ(HF)--concentration of HF in fixed pollution source exhaust gas, mg/m3;
- the concentration of fluoride ions in the sample, μg/ml;
Ρ0--the concentration of fluoride ion in the blank sample, μg/ml;
V--the volume after dilution of the sample, ml;
Vnd--the sampling volume of dry exhaust gas under standard conditions (273K, 101.325kPa), L.
8.2 Results representation
When the concentration of hydrogen fluoride is ≥ 1.00 mg/m3, the results retain three significant figures; when the concentration is < 1.00 mg/m3, the results are retained.
Two significant figures.
9 Quality Assurance and Quality Control
9.1 At least one full program blank shall be made for each batch of samples, and the blank value shall not exceed the method detection limit. Otherwise you should find the reason,
The sample can be analyzed after reanalysis until it is qualified.
9.2 A calibration curve shall be drawn for each sample analysis. The correlation coefficient of the calibration curve shall be ≥0.995.
9.3 For each sample of 20 samples or one batch (less than 20 samples), the middle point of a calibration curve should be analyzed
The relative error of the concentration of the standard solution and the concentration of the point at the point of the most recent calibration curve should be ≤10%. Otherwise
Redraw the standard curve.
9.4 At least 10% of the spiked sample shall be determined for each batch of samples. When the number of samples is less than 10, at least one spiked sample shall be determined.
The standard recovery rate should be between 80% and 120%.
10 Waste treatment
Recyclable waste is recovered, and non-recyclable waste is disposed of by a qualified professional company.
11 Precautions
11.1 The concentration of the absorption liquid is higher than the concentration of the eluent. When the concentration difference between the two is large, the measurement error is large. Therefore, the sample solution
Dilute 3.3 times before the measurement to make the sample solution and eluent concentration similar.
11.2 When the concentration of hydrogen fluoride in the exhaust gas is low, the sampling volume may be increased and/or the volume after dilution of the sample may be reduced;
When the hydrogen concentration is high, the sampling volume can be reduced and/or the volume after dilution of the sample can be increased; when the sample is diluted, the volume changes.
The concentration of the prepared eluent should be adjusted accordingly.
11.3 When the sample contains particles with a particle size of more than 0.45 μm, the particles will affect the ion chromatography column and the sample dissolves.
Pre-filtration of the liquid before entering the ion chromatograph can eliminate this effect.
11.4 Bubbles have an effect on the separation of the ion column, and no bubbles can be introduced during injection.
11.5 Borosilicate glass is chemically inert, acid and alkali resistant, and resistant to corrosion. It can be used at 800 °C. Quartz
Learn to be inert and resistant to HF and can be used at 900 °C. Titanium alloy is chemically inert, smooth surface and resistant to corrosion
The etch can be used at temperatures between 450 ° C and 550 ° C. The temperature of PTFE should not be higher than 250 °C, otherwise it will decompose and release fluorine.
Compound. New PTFE devices may release fluoride gas and require heat treatment at the sampled temperature in advance.
11.6 During the constant current sampling operation, when the exhaust gas begins to flow through the main path, in order to prevent the absorption of the bypassed absorption liquid,
The bypass shut-off valve should be closed first, then the main circuit shut-off valve. In addition, since both shut-off valves are located in the heating range
In the enclosure, the temperature is high, and wear gloves should be worn during operation to prevent burns.
11.7 The sensitivity of this method is high, and the absorption tube, connecting tube and individual utensils should be carefully washed. Pay attention to prevent tap water during operation.
Interference with fluoride in the air.
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