HJ 547-2017_English: PDF (HJ547-2017)
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Stationary source emission -- Determination of chlorine--Iodometric method
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HJ 547-2017
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| HJ 547-2009 | English | 319 |
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Stationary source emission. Determination of chlorine. Iodometric method
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HJ 547-2009
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| Standard ID | HJ 547-2017 (HJ547-2017) | | Description (Translated English) | Stationary source emission -- Determination of chlorine--Iodometric method | | Sector / Industry | Environmental Protection Industry Standard | | Word Count Estimation | 11,157 | | Date of Issue | 2017-12-29 | | Date of Implementation | 2018-04-01 | | Older Standard (superseded by this standard) | HJ 547-2009 | | Drafting Organization | Chinese Academy of Environmental Sciences | | Administrative Organization | Ministry of Environmental Protection | | Regulation (derived from) | Ministry of Environmental Protection Bulletin 2017 No. 86 | | Standard ID | HJ 547-2009 (HJ547-2009) | | Description (Translated English) | Stationary source emission. Determination of chlorine. Iodometric method | | Sector / Industry | Environmental Protection Industry Standard | | Classification of Chinese Standard | Z25 | | Classification of International Standard | 13.040.40 | | Word Count Estimation | 8,857 | | Date of Issue | 2009-12-30 | | Date of Implementation | 2010-04-01 | | Quoted Standard | HJ/T 373; GB/T 16157; GB/T 6682 | | Drafting Organization | Beijing Municipal Environmental Monitoring Center | | Administrative Organization | Ministry of Environment Protection | | Regulation (derived from) | Department of Environmental Protection Notice No. 74 of 2009 | | Summary | This standard specifies the determination of stationary source emissions of chlorine iodometric method. This standard applies to stationary source emissions Determination of chlorine. The detection limit is 0. 03��g, sampling volume is 10L, the detection limit is 12mg/m ^ 3. |
HJ 547-2017
People's Republic of China national environmental protection standards
Replacing HJ 547-2009
Stationary sources - Determination of chlorine gas - Iodometric method
Stationary source emission - Determination of chlorine-Iodometric method
2017-12-29 Posted
2018-04-01 implementation
Ministry of Environmental Protection released
Directory
Foreword .ii
1 scope of application .1
2 Normative references .1
3 method principle .1
4 Interference and elimination .1
5 Reagents and materials .2
6 instruments and equipment .3
7 samples .3
8 Analysis steps .5
9 results calculated and said .5
10 precision and accuracy 6
11 Quality Assurance and Quality Control .6
12 Waste treatment 6
13 Matters needing attention 7
Foreword
In order to implement "Law of the People's Republic of China on Environmental Protection" and "Law of the People's Republic of China on Prevention and Control of Atmospheric Pollution," Paul
Protect the environment, protect human health, standardize the determination of chlorine in exhaust gas pollution sources, the development of this standard.
This standard specifies the amount of iodine method for the determination of chlorine emissions from organized sources of emissions of fixed sources of pollution.
This standard is "a fixed source of emissions of chlorine gas Determination of iodine method (Interim)" (HJ 547-2009) amendment.
This standard was first released in.2009, the original standard drafting unit for the Beijing Municipal Environmental Protection Monitoring Center, this is the first time
The main content of the revision and amendment are as follows.
- Revised methods of reagents and materials, apparatus and equipment, reagent preparation, sample collection and analysis steps and other articles
paragraph.
- Complement and improve the method of principle, interference and eliminate some of the content.
- Added precision, accuracy, result representation, sample penetration experiments, quality assurance and quality control
content.
- Added waste disposal content.
Since the implementation of this standard, "fixed sources of chlorine emissions Determination of iodine method (Interim)" (HJ 547-2009)
Abolished.
This standard by the Environmental Protection Department of Environmental Monitoring Division and Science and Technology Standards Division to develop.
This standard was drafted. Beijing Environmental Protection Monitoring Center.
This standard verification unit. Beijing Environmental Protection Monitoring Center, Changping District, Beijing Environmental Protection Monitoring Station, Beijing North Korea
Yang District Environmental Protection Bureau, Fengtai District, Beijing Environmental Protection Monitoring Station, Beijing Kangju Environmental Monitoring Station and the Beijing Municipal Physical and Chemical Analysis
test Center.
This standard MEP approved on December 29,.2017.
This standard since April 1,.2018 come into operation.
This standard is interpreted by the MEP.
Stationary sources - Determination of chlorine gas - Iodometric method
Warning. chlorine gas is harmful to the human body. When sampling, wear protective equipment as required to avoid inhalation, contact with skin and eyes.
1 scope of application
This standard specifies the determination of iodine content of chlorine gas emissions from fixed sources of pollution.
This standard applies to fixed sources of emissions of organized emissions of chlorine gas, does not apply to the determination of unorganized emissions.
When the sampling volume is 10 L, the detection limit is 12 mg/m3 and the lower limit of determination is 48 mg/m3.
2 Normative references
This standard references the following documents in the terms. For undated references, the effective version applies to this book
standard.
GB/T 16157 fixed emission sources of particulate matter measurement and gaseous pollutants sampling method
HJ/T 47 gas sampler technical conditions
3 method principle
Chlorine is absorbed by the sodium hydroxide solution to produce sodium hypochlorite. After the sample was added potassium iodide, acidified with hydrochloric acid, released
Free chlorine oxidizes iodide ions to iodine and titrates with sodium thiosulfate standard solution. Based on consumption of sodium thiosulfate standard solution
Volume and sampling volume, calculate the concentration of chlorine in the exhaust gas. The reaction is as follows.
2NaOH Cl2 → NaCl H2O NaClO
NaClO HCl → NaOH Cl2
Cl2 2KI → 2KCl I2
I2 2Na2S2O3 → 2NaI Na2S4O6
4 Interference and elimination
Hydrogen fluoride in the exhaust gas and hydrogen chloride do not interfere with the determination; particles will affect the determination, can be added in front of the sampling tube filter to remove;
Exhaust gases contain other oxidizing or reducing gases that interfere with the assay.
5 Reagents and materials
Unless otherwise specified, analytical grade reagents and distilled water are used in accordance with national standards.
5.1 Hydrochloric acid. ρ (HCl) = 1.19 g/ml, excellent grade pure.
5.2 potassium iodide (KI).
5.3 potassium iodate (KIO3). reference reagent or excellent grade pure.
5.4 Sodium hydroxide (NaOH).
5.5 Sodium thiosulfate pentahydrate (Na2S2O3 · 5H2O).
5.6 anhydrous sodium carbonate (Na2CO3).
5.7 hydrochloric acid solution. 2 1.
Take 250 ml of hydrochloric acid (5.1), add to 125 ml of water and mix well.
5.8 Hydrochloric acid solution. c (HCl) = 1.2 mol/L.
Measure 100 ml of hydrochloric acid (5.1) slowly into 900 ml of water.
5.9 Sodium hydroxide absorbent. ρ (NaOH) = 4.0 g/L.
Weigh 4.0 g sodium hydroxide (5.4), dissolved in a small amount of water, diluted to 1000 ml.
5.10 potassium iodate standard solution. c (1/6 KIO3) = 0.1000 mol/L.
Weigh accurately 3.567 g at 105 ℃ ~ 110 ℃ drying 2 h and cooled in a desiccator potassium iodate (5.3), dissolved in water,
Move into a 1000 ml volumetric flask, dilute to the mark, shake well and store in a brown glass stopper. Room temperature preservation, preservation
The time is generally not more than two months. When the solution appears cloudy, precipitation, color changes and other phenomena, should be re-formulated.
5.11 sodium thiosulfate standard solution. c (Na2S2O3) ≈ 0.1 mol/L.
Weigh 25 g of sodium thiosulfate pentahydrate (5.5), dissolved in freshly boiled and chilled water, add 0.20 g of anhydrous carbonated
Sodium (5.6), dissolved, mixed, set to 1000 ml, stored in a brown glass bottle. If the solution is cloudy, it should be added
To filter. 0 ℃ ~ 4 ℃ can be stored for 6 months, temporary calibration.
Calibration method. Pipette 10.00 ml potassium iodate standard solution (5.10), placed in 250 ml iodine bottle, add 85 ml
Freshly boiled and cooled water, add 1.0 g of potassium iodide (5.2), shake to completely dissolve, then add 10.0 ml of hydrochloric acid
Liquid (5.8), immediately covered the bottle stopper, mix well. After 5 min in the dark place, with the standard solution of sodium thiosulfate to be calibrated (5.11)
Titration to light yellow, add 5 ml of starch indicator (5.13), continue titration until the blue just fade, record consumption of thiosulfuric acid
Volume of sodium standard solution (V). According to formula (1) calculate the concentration of sodium thiosulfate standard solution.
() 2 2 3 c Na SO =
0.1000 10.00
(1)
Where. C (Na2S2O3) - sodium thiosulfate standard solution concentration, mol/L;
V - Titration potassium iodate standard solution of sodium thiosulfate standard solution volume, ml.
5.12 sodium thiosulfate standard solution c (Na2S2O3) ≈ 0.01 mol/L.
Pipette 50.00 ml of calibrated sodium thiosulfate standard solution (5.11), placed in 500 ml volumetric flask, with a new boil
And has been diluted with water cooling to the mark, shake average, Pro use now.
5.13 Starch indicator. p = 0.002 g/ml.
Weigh 0.20 g of soluble starch, add a small amount of water into a paste, slowly pour 100 ml boiling water, continue to boil until the solution
Clarified, cooled and stored in stoppered glass bottles, ready for use.
5.14 Microporous cellulose acetate membrane or quartz filter.
The retention efficiency of particles larger than 0.3 μm is not less than 99.9%.
6 instruments and equipment
Unless otherwise specified, all glassware used in accordance with the national standard Class A was used for the analysis.
6.1 flue gas sampler. the sampling flow 0 L/min ~ 1 L/min, other performance and technical indicators should be consistent with the provisions of HJ/T 47.
6.2 Filter Clip. Teflon material, size and filter (5.14) match.
6.3 sampling tube. hard glass or PTFE material. The inner diameter should be larger than 6 mm, and should be attached to heat up to 120 ° C
More insulation jacket.
6.4 Connecting pipe. Teflon hose or silicone rubber tube lined with Teflon film. The connection method is the internal jacket method
connection.
6.5 Porous glass absorption bottle. 125 ml scale. Glass panels require 2/3 area of fine and uniform foam, no bubbles at the edge
Escape, with a flow rate of 0.5 L/min, the resistance should be (5 ± 0.7) kPa.
6.6 Brown Acid Burette. 25 ml.
6.7 iodine bottle. 250 ml.
6.8 General laboratory equipment and equipment.
7 samples
7.1 Sample Collection
7.1.1 sampling point layout and sampling methods should be consistent with the provisions of GB/T 16157.
7.1.2 Connect in series two porous glass absorption bottles (6.5) containing 40 ml of sodium hydroxide absorbent (5.9), connect to
Sampling system, with 0.5 L/min ~ 1 L/min constant current sampling 20 min ~ 30 min. If the exhaust contains solid particles
Things should be placed in the filter membrane (5.14) folder (6.2), then mounted on the front end of the sampling tube, the sampling system shown in Figure 1. When waste
When the temperature is higher than the ambient temperature or the moisture content is large, it is necessary to heat the filter membrane and the sampling tube in the filter holder to keep the sampling tube insulated
Jacket temperature at 120 ℃, to prevent moisture condensation. Record the sampling flow rate, time, temperature, pressure, etc. After sampling,
Seal the outlet of the absorbent bottle with a connecting tube (6.4) and back to the laboratory in the dark.
Note. When the chlorine concentration, moisture content (flue gas moisture content above 25%), the need for constant speed sampling.
Figure 1 Schematic diagram of a chlorine sampling system in a stationary source of exhaust gas
7.2 full program blank sample
The same batch of 40 ml of sodium hydroxide solution (5.9) of the two tandem absorption bottle to the sampling site, not with the sample
Connection, after the sample is taken with the collected samples back to the laboratory.
7.3 Sample Storage
Samples should be analyzed as soon as possible after the sample is collected. If it can not be measured on the same day, it should be refrigerated below 4 ℃ and be measured within 48 h.
7.4 Sample Preparation
7.4.1 Samples
The absorption of the first stage absorption bottle was transferred to a 100 ml volumetric flask, the second level with an absorbent absorption of the washing liquid
After the first bottle into the volumetric flask, and then a small amount of water to wash the two absorption bottles and absorption tube, washing liquid into the volumetric flask together, plus
Water to the mark, mix well.
7.4.2 Blank sample
7.4.2.1 full program blank
Preparation of the entire program blank sample was carried out according to the same procedure as for sample preparation (7.4.1).
7.4.2.2 reagent blank
Take the same batch of absorbent (5.9) instead of the sample, according to the same steps as the sample preparation (7.4.1) reagent blank
Preparation.
7.4.3 penetrate the experimental sample
Respectively, the absorption of the first and second absorption bottles were transferred to a 50 ml volumetric flask, then a small amount of water
Wash two absorption bottles, washing liquid into the flask, add water to the mark, mix well.
8 Analysis steps
8.1 Determination of the sample
Pipette 25.0 ml sample (7.4.1) in iodine bottle, add an equal volume of water, add 2.0 g of potassium iodide (5.2), to be dissolved
After the solution, add 10.0 ml hydrochloric acid solution (5.7), plug tightly, mix well and place in dark place for 5 min. With sodium thiosulfate standard make
Titration with liquid (5.12) to pale yellow, add 5 ml of starch solution (5.13), continue titration until the blue just disappears,
Record consumption of sodium thiosulfate standard use volume (V).
8.2 blank sample determination
Follow the same procedure as described for sample determination (8.1) to determine the full program blank and reagent blank.
8.3 Penetration of experimental samples
Following the same procedure as for sample determination (8.1), the penetration test sample (7.4.3) was measured and the consumption recorded.
9 results calculated and expressed
9.1 Calculation Results
The concentration of chlorine in the exhaust gas is calculated according to equation (2)
(Cl2) = 1000 () 35.5 0
nd V
VV c
(2)
Where. 2 (Cl) - concentration of chlorine in the exhaust gas, mg/m3;
Volume of standard sodium thiosulfate consumed by titration of V - titration sample solution, ml;
0 V - titration reagent blank solution consumed sodium thiosulfate standard volume of liquid used, ml;
c - sodium thiosulfate standard solution concentration, mol/L;
35.5 - Molar mass of chlorine (1/2 Cl2), g/mol;
nd V - Converted to the gas recovery volume of dry exhaust under standard conditions (0 ° C, 101.325 kPa), L
t V - total volume of sample solution, ml;
a V - volume of sample solution taken during titration, ml.
9.2 results indicated
When the measurement is less than 100 mg/m3, retained to the whole digit; when the measurement is greater than or equal to 100 mg/m3,
Keep three significant figures.
10 precision and accuracy
10.1 Precision
Six laboratories separately treated sodium hypochlorite solution with available chlorine concentrations of 9.01 mg/L, 72.6 mg/L and 181 mg/L
The relative standard deviations in the laboratory were 1.2% ~ 2.1%, 0.32% ~ 1.1% and 0.2% ~ 1.5%, respectively.
The relative standard deviations (RSDs) of laboratory were 5.7%, 7.3% and 7.5%, respectively. The repeatability limits were 0.40 mg/L, 1.7 mg/L
And 4.0 mg/L respectively. The reproducibility limits were 1.5 mg/L, 15 mg/L and 38 mg/L, respectively.
Six laboratories performed standard gas concentrations of 22.4 mg/m3, 78.9 mg/m3 and 735 mg/m3 chlorine respectively
The relative standard deviations in the laboratory were 3.8% ~ 6.5%, 1.6% ~ 3.6% and 0.6% ~ 2.1%, respectively. The experiment
The relative standard deviations (RSDs) were 1.9%, 1.6% and 3.4% respectively. The repeatability limits were 3 mg/m3 and 3 mg/m3, respectively
30 mg/m3; reproducibility limits are 3 mg/m3, 6 mg/m3 and 70 mg/m3, respectively.
10.2 Accuracy
Six laboratories performed standard gas concentrations of 22.4 mg/m3, 78.9 mg/m3 and 735 mg/m3 chlorine respectively
The relative error in the laboratory was -5.4% -10%, -3.6% -7.5% and -2.0% -9.2% respectively. The experiment
The relative error between rooms was -7.5%, -6.0% and -5.5%, respectively. The final relative error values were -7.5% ± 2.0%
-6.0% ± 3.2% and -5.5% ± 6.3%.
Six laboratories performed standard gas concentrations of 22.4 mg/m3, 78.9 mg/m3 and 735 mg/m3 chlorine respectively
Repeated determination, the laboratory absorption efficiency were 91.7% ~ 94.6%, 92.5% ~ 96.8% and 90.8% ~ 98.0%;
Laboratory absorption efficiency were 93.2%, 94.0% and 94.5% respectively.
11 Quality Assurance and Quality Control
11.1 Sampling Each batch of samples should be at least 1 full blank and 2 reagent blank. Full program blank and reagent blank
The measured value should be below the detection limit of the method.
11.2 Before analyzing the sample, the standard solution of sodium thiosulfate should be calibrated. The relative value of the single titration result should not be too high
More than 0.2%, double titration results poor relative value of not more than 0.5%.
11.3 Parallel titration shall be performed on at least 10% of the samples in each batch of samples, with a relative deviation of no more than 2%.
11.4 Penetration test and absorption efficiency analysis of samples collected at low and high concentrations of chlorine (up to 735 mg/m3)
From the point of view, the complete absorption of the gas sample can be achieved by connecting two absorption bottles in series, but if the actual sample concentration is high,
To increase the penetration of the experimental link, each batch of samples collected should be done through a penetration test, when the second absorption bottle of chlorine content
More than 10% of the first absorption bottle content, that has been penetrated, should reduce gas production or gas production time, re-sampling.
12 Waste treatment
The waste liquid and waste generated during the experiment shall be stored in categories, centrally stored and entrusted to qualified units for disposal.
13 Precautions
Sampling absorption bottle inlet port and the series of two absorption bottle is not available between the latex hose connection should be polytetrafluoroethylene
Hose or polyethylene plastic pipe connected to the jacket method, the plastic tube is about to be inserted into the mouth of the absorption bottle, wrapped with PTFE tape
Well, then use a silicone rubber pipe outside the mouth. The connecting pipe should be as short as possible.
......
HJ 547-2009
Stationary source emission.Determination of chlorine.Iodometric method
National Environmental Protection Standard of the People's Republic
Determination of chlorine gas from fixed pollution source
Iodometric method (provisional)
Stationary source emission-Determination of chlorine
-Iodometric method
Released.2009-12-30
2010-04-01 Implementation
Ministry of Environmental Protection released
Ministry of Environmental Protection
announcement
No. 74 of.2009
In order to implement the "Environmental Protection Law of the People's Republic of China", protect the environment, and protect human health, we now approve the lead gas of fixed pollution sources.
The four standards, such as the determination of flame atomic absorption spectrophotometry (tentative), are national environmental protection standards and are released.
The standard name and number are as follows.
I. Determination of lead in fixed pollution sources - Flame atomic absorption spectrophotometry (tentative) (HJ 538-2009);
2. Determination of lead in ambient air by graphite furnace atomic absorption spectrophotometry (tentative) (HJ 539-2009);
III. Determination of arsenic in ambient air and exhaust gases - Spectrophotometric method of silver diethyldithiocarbamate (interim) (HJ 540-2009);
4. Determination of gaseous arsenic in the production of yellow phosphorus - Determination of silver diethyldithiocarbamate spectrophotometry (interim) (HJ 541-2009);
V. Determination of mercury in ambient air - Enrichment of sulfhydryl cotton - Cold atomic fluorescence spectrophotometry (interim) (HJ 542-2009);
6. Determination of mercury in fixed pollution sources - Cold atomic absorption spectrophotometry (provisional) (HJ 543-2009);
VII. Determination of Sulfuric Acid Fog of Fixed Pollution Sources by Ion Chromatography (Provisional) (HJ 544-2009);
VIII. Determination of gaseous total phosphorus in fixed pollution sources - Determination of quinolinol ketone capacity (provisional) (HJ 545-2009);
IX. Determination of Phosphorus Pentoxide in Ambient Air Ascorbic Acid Reduction - Molybdenum Blue Spectrophotometry (Provisional) (HJ 546-2009);
XI. Determination of hydrogen chloride in fixed source pollution. Silver nitrate capacity method (provisional) (HJ 548-2009);
12. Determination of hydrogen chloride in ambient air and exhaust gas Ion chromatography (interim) (HJ 549-2009);
XIII. Determination of total cobalt in water quality 5-chloro-2-(pyridylazo)-1,3-diaminobenzene spectrophotometry (provisional) (HJ 550-2009);
14. Determination of Chlorine Dioxide in Water Quality Iodometric Method (Provisional) (HJ 551-2009).
The above standards have been implemented since April 1,.2010 and published by the China Environmental Science Press. The standard content can be found on the website of the Ministry of Environmental Protection.
Special announcement.
December 30,.2009
Content
Foreword..iv
1 Scope..1
2 Normative references..1
3 method principle..1
4 interference.1
5 Reagents and materials.1
6 instruments and equipment.2
7 samples. 2
8 Analysis steps..3
9 result calculation..3
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 Air Pollution"
This standard is formulated for the prevention of human health and the regulation of chlorine in the fixed source of waste gas.
This standard specifies the method of determining the amount of chlorine in the fixed source of waste gas.
This standard was formulated by the Science and Technology Standards Department of the Ministry of Environmental Protection.
This standard was drafted. Beijing Environmental Protection Monitoring Center.
This standard was approved by the Ministry of Environmental Protection on December 30,.2009.
This standard has been implemented since April 1,.2010.
This standard is explained by the Ministry of Environmental Protection.
Iv
Determination of chlorine in fixed waste gas sources - Determination of iodometric method (interim)
Warning. When sampling at the site, if the chlorine concentration is high, the operator should be in the upwind direction and take the anti-virus mask operation.
Anti-chlorine gas poisoning.
1 Scope of application
This standard specifies the method of determining the amount of chlorine in the fixed source of waste gas.
This standard applies to the determination of chlorine in fixed source exhaust gas.
The detection limit of this method is 0.03 μg; when the sampling volume is 10 L, the detection limit is 12 mg/m3.
2 Normative references
The contents of this standard refer to the terms in the following documents. For undated references, the valid version applies to this standard.
GB/T 16157 Determination of particulate matter in fixed pollution source exhaust gas and sampling method of gaseous pollutants
HJ/T 373 Technical Specifications for Quality Assurance and Quality Control of Fixed Pollution Source Monitoring (Trial)
GB/T 6682 Analytical laboratory water specifications and test methods
3 Principle of the method
The chlorine gas is absorbed by the sodium hydroxide solution to form sodium hypochlorite, which is acidified with hydrochloric acid to release free chlorine. The reaction formula is as follows.
22NaOH Cl → 2NaCl HO NaClO
NaClO HCl → 2NaOH Cl
Free chlorine reoxidizes the iodide to form iodine, which is titrated with a sodium thiosulfate standard solution to calculate the amount of chlorine.
2Cl 2KI → 22KCl I
2 2 2I 2Na SO 3→ 2 4 62NaI Na SO
4 interference
When hydrogen chloride is contained in the exhaust gas, the measurement is not disturbed; there is interference when it contains oxidizing and reducing gases.
5 reagents and materials
Unless otherwise stated, analytically pure reagents in accordance with national standards were used for the analysis; experimental water, GB/T 6682, grade 3.
5.1 Hydrochloric acid. ρ (HCl) = 1.19 g/ml, excellent grade pure.
5.2 Potassium iodide crystal (KI). excellent grade pure.
5.3 Potassium iodate (KIO3). excellent grade pure.
5.4 Hydrochloric acid solution. 2 1.
Formulated with hydrochloric acid (5.1).
5.5 Hydrochloric acid solution. c (HCl) = 1.2 mol/L.
Measure 100 ml of concentrated hydrochloric acid (5.1) and dilute to 1 000 ml with water.
5.6 Sodium hydroxide absorption solution. w (NaOH) = 0.4%.
Weigh 4.0 g of sodium hydroxide, dissolve in water and dilute to 1 000 ml.
5.7 Potassium iodate standard solution. c (1/6KIO3) = 0.100 0 mol/L.
Weigh 3.567 g of potassium iodate (5.3) which is dried at 105-110 ° C for 2 h and cooled. Dissolve in water, transfer to a 1 000 ml volumetric flask, and dilute.
Shake to the mark, shake it, and store in a brown stoppered glass bottle.
5.8 Sodium thiosulfate standard solution. c (Na2S2O3) ≈ 0.1 mol/L.
Weigh 25 g of sodium thiosulfate (Na2S2O3·5H2O), dissolve in freshly boiled and cooled water, add 0.20 g of anhydrous sodium carbonate, dilute
Release to 1 000 ml and store in a brown glass bottle. If the solution is cloudy, it should be filtered. 0 to 4 ° C can be stored for 6 months, Pro
Use calibration.
Calibration method. Pipette 10.00 ml of potassium iodate standard solution (5.7), place it in a 250 ml iodine measuring flask, add 85 ml of new boiled and
Cool the water, add 1.0 g potassium iodide (5.2), shake to complete dissolution, then add 10.0 ml hydrochloric acid solution (5.5), immediately cover the bottle
Plug and mix. After 5 min in dark treatment, titrate with sodium thiosulfate solution (5.8) until pale yellow, add 5 ml starch indicator (5.10),
Continue titration until the blue color just fades and record the volume (V) of the sodium thiosulfate solution consumed. Calculate sodium thiosulfate solution according to formula (1)
concentration.
0.01 10.00(Na SO )c
×= (1)
Where. - concentration of sodium thiosulfate solution, mol/L; 2 2 3 (Na SO ) c
V--The volume of the sodium thiosulfate solution used to calibrate potassium iodate, ml.
5.9 sodium thiosulfate standard use solution
Pipette 50.00 ml of the calibrated sodium thiosulfate solution (5.8) into a 500 ml volumetric flask and dilute with freshly boiled and cooled water.
Released to the marking line, shaken, and ready to use.
5.10 Starch indicator. w = 0.20%.
Weigh 0.20 g of soluble starch, add a small amount of water to make a paste, slowly pour into 100 ml of boiling water, continue to boil until the solution is clear, cold
However, it is stored in a fine mouth bottle and is ready for use.
6 Instruments and equipment
Unless otherwise stated, the analysis used a Class A glass instrument in accordance with national standards.
6.1 Flue gas sampler. 0~1 L/min.
6.2 Sampling tube. glass or Teflon.
Note. Chlorine gas produces hydrochloric acid and hypochlorous acid in the presence of water vapor, which is highly corrosive. Therefore, the sampling tube should be made of glass or Teflon.
Work.
6.3 Porous glass plate absorption bottle. 125 ml.
6.4 Brown acid burette. 25 ml or 50 ml.
6.5 Iodometric flask. 250 ml.
7 samples
7.1 Sample Collection
The sampling point layout and sampling method are performed according to GB/T 16157. When sampling, two porous glass plate absorption bottles are connected in series, and each bottle is packed with 30~
40 ml sodium hydroxide absorption solution (5.6), sample at a flow rate of 0.5 to 1 L/min, and sample for 10 to 30 minutes.
7.2 Sample storage
Sample collection should be analyzed as soon as possible. If it cannot be measured on the same day, the sample should be sealed and placed in the refrigerator, stored at 0~4 °C, and measured within 5 days.
8 Analysis steps
8.1 Sample preparation
After sampling, transfer all the two sample solutions to a 100 ml volumetric flask, and wash the absorption tube and the absorption bottle with the absorbent (5.6).
And transfer to this volumetric flask, add the absorption liquid to the marking line, and mix.
8.2 Determination of samples
Pipette 25.00 ml of sample (8.1) into an iodine measuring flask, add an equal volume of water, add 2.0 g of potassium iodide (5.2), add to dissolve, add
10.0 ml hydrochloric acid solution (5.4), tightly packed, mixed, placed in the dark for 5 min. Titrate to pale yellow with sodium thiosulfate standard solution (5.9).
Add 5 ml of starch solution (5.10), continue titration until the blue color just disappears, and record the consumption (V).
8.3 Blank sample determination
Take 25.00 ml of the absorption solution, add an equal volume of water, and perform a blank titration to record the consumption (V0).
9 Calculation of results
The chlorine content is calculated according to formula (2)
0 t
Nd a
( ) 35.5
(Cl ) 1000
VV c V
VV
ρ − × ×= × × (2)
Where. - chlorine content, mg/m3; 2 (Cl ) ρ
V--the volume of the sodium thiosulfate standard solution consumed by the titration sample solution, ml;
V0--the volume of the sodium thiosulfate standard solution consumed by titrating the blank sample solution, ml;
C--sodium thiosulfate standard use liquid concentration, mol/L;
35.5- molar mass of chlorine (1/2Cl2), g/mol;
Vt--the total volume of the sample solution, ml;
Va--the volume of the sample solution taken by the titration, ml;
Vnd--the gas production volume of dry exhaust gas converted to the standard state (101.325 kPa, 273 K), L.
......
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