CN116642999A - Method for measuring sulfur dioxide and hydrogen sulfide gas content in mixed gas - Google Patents
Method for measuring sulfur dioxide and hydrogen sulfide gas content in mixed gas Download PDFInfo
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- CN116642999A CN116642999A CN202310719154.5A CN202310719154A CN116642999A CN 116642999 A CN116642999 A CN 116642999A CN 202310719154 A CN202310719154 A CN 202310719154A CN 116642999 A CN116642999 A CN 116642999A
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- 239000007789 gas Substances 0.000 title claims abstract description 156
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 title claims abstract description 108
- 229910000037 hydrogen sulfide Inorganic materials 0.000 title claims abstract description 79
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 title claims abstract description 73
- 238000000034 method Methods 0.000 title claims abstract description 57
- 239000000243 solution Substances 0.000 claims abstract description 45
- 239000007788 liquid Substances 0.000 claims abstract description 39
- 238000004448 titration Methods 0.000 claims abstract description 37
- 239000012086 standard solution Substances 0.000 claims abstract description 31
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 30
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 29
- 239000011593 sulfur Substances 0.000 claims abstract description 29
- 238000006243 chemical reaction Methods 0.000 claims abstract description 18
- ZOIORXHNWRGPMV-UHFFFAOYSA-N acetic acid;zinc Chemical compound [Zn].CC(O)=O.CC(O)=O ZOIORXHNWRGPMV-UHFFFAOYSA-N 0.000 claims abstract description 13
- 239000004246 zinc acetate Substances 0.000 claims abstract description 13
- 239000002244 precipitate Substances 0.000 claims abstract description 9
- 238000006479 redox reaction Methods 0.000 claims abstract description 6
- 238000004364 calculation method Methods 0.000 claims abstract description 5
- 229910000365 copper sulfate Inorganic materials 0.000 claims abstract description 5
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 claims abstract description 5
- 239000002253 acid Substances 0.000 claims abstract description 3
- OMZSGWSJDCOLKM-UHFFFAOYSA-N copper(II) sulfide Chemical compound [S-2].[Cu+2] OMZSGWSJDCOLKM-UHFFFAOYSA-N 0.000 claims abstract description 3
- 238000010521 absorption reaction Methods 0.000 claims description 38
- 238000005070 sampling Methods 0.000 claims description 23
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 claims description 22
- 229910052740 iodine Inorganic materials 0.000 claims description 22
- 239000011630 iodine Substances 0.000 claims description 22
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 claims description 22
- 235000019345 sodium thiosulphate Nutrition 0.000 claims description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 claims description 15
- 238000005406 washing Methods 0.000 claims description 15
- 108010010803 Gelatin Proteins 0.000 claims description 12
- 229920000159 gelatin Polymers 0.000 claims description 12
- 239000008273 gelatin Substances 0.000 claims description 12
- 235000019322 gelatine Nutrition 0.000 claims description 12
- 235000011852 gelatine desserts Nutrition 0.000 claims description 12
- 238000005259 measurement Methods 0.000 claims description 12
- 238000012360 testing method Methods 0.000 claims description 12
- 229920002472 Starch Polymers 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 11
- 235000019698 starch Nutrition 0.000 claims description 11
- 239000008107 starch Substances 0.000 claims description 11
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 10
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 10
- 239000012153 distilled water Substances 0.000 claims description 9
- 230000003287 optical effect Effects 0.000 claims description 9
- 239000011734 sodium Substances 0.000 claims description 8
- 238000009423 ventilation Methods 0.000 claims description 6
- 229960000583 acetic acid Drugs 0.000 claims description 5
- 239000012362 glacial acetic acid Substances 0.000 claims description 5
- 239000003153 chemical reaction reagent Substances 0.000 claims description 4
- 239000013078 crystal Substances 0.000 claims description 4
- 229910052979 sodium sulfide Inorganic materials 0.000 claims description 4
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 claims description 4
- 238000012937 correction Methods 0.000 claims description 3
- 238000007865 diluting Methods 0.000 claims description 3
- MAHNFPMIPQKPPI-UHFFFAOYSA-N disulfur Chemical compound S=S MAHNFPMIPQKPPI-UHFFFAOYSA-N 0.000 claims description 3
- 239000000839 emulsion Substances 0.000 claims description 3
- 229920006395 saturated elastomer Polymers 0.000 claims description 3
- 238000004879 turbidimetry Methods 0.000 claims description 3
- 238000005303 weighing Methods 0.000 claims description 3
- 239000007864 aqueous solution Substances 0.000 claims description 2
- 238000010790 dilution Methods 0.000 claims description 2
- 239000012895 dilution Substances 0.000 claims description 2
- 238000011010 flushing procedure Methods 0.000 claims description 2
- 230000035772 mutation Effects 0.000 claims description 2
- 238000001514 detection method Methods 0.000 description 21
- 238000004458 analytical method Methods 0.000 description 5
- 230000033116 oxidation-reduction process Effects 0.000 description 5
- 238000012544 monitoring process Methods 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 2
- 231100000331 toxic Toxicity 0.000 description 2
- 230000002588 toxic effect Effects 0.000 description 2
- 238000012795 verification Methods 0.000 description 2
- 239000005864 Sulphur Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000004868 gas analysis Methods 0.000 description 1
- 230000007794 irritation Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000009965 odorless effect Effects 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 150000003464 sulfur compounds Chemical class 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/16—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using titration
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
- G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
- G01N21/82—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a precipitate or turbidity
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
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Abstract
The invention discloses a method for measuring the content of sulfur dioxide and hydrogen sulfide gas in mixed gas, which adopts a two-step method to measure the accurate content of each component in the mixed gas; absorbing the mixed gas by zinc acetate solution, dissolving the precipitate generated by the reaction by acid, and then mixing with a certain amount of I 2 The standard solution undergoes oxidation-reduction reaction, and excessive I 2 With Na 2 S 2 O 3 Titration of the solution according to Na 2 S 2 O 3 Obtaining total sulfur content in the liquid according to the standard liquid consumption; and then absorbing the mixed gas through a copper sulfate solution, generating copper sulfide precipitate at the moment, determining the content of sulfur in the hydrogen sulfide by measuring the precipitate, subtracting the content of sulfur in the hydrogen sulfide from the total sulfur content to obtain the content of sulfur dioxide in the mixed gas, and finally obtaining the accurate contents of the hydrogen sulfide and the sulfur dioxide by calculation. The invention can detect hydrogen sulfide and sulfur dioxide gasThe volume content has higher practical value.
Description
Technical Field
The invention relates to gas analysis, in particular to a method for measuring the content of each component in sulfur dioxide and hydrogen sulfide mixed gas.
Background
Chemistry is a special subject, which is an experimental technique focusing on the staff of the studyAbility and experimental exploration ability. The sulfur compound content is focused on experimental study of sulfur dioxide properties, and the experimental content is too dispersed and has low content aiming at hydrogen sulfide gas components. The test for measuring the mixed gas of the hydrogen sulfide and the sulfur dioxide is the most common test at present, but because the sulfur dioxide and the hydrogen sulfide are colorless gases and have strong irritation and toxicity, once the mixed gas is improperly treated, serious influence is easily brought. Thus, in the determination of the sulfide component content in the mixed gas, a six-in-one gas analyzer (capable of detecting O 2 、LEL、NH 3 、CO、SO 2 、H 2 S) during detection and detection by a smoke tester, sulfur dioxide and hydrogen sulfide gas are displayed (shown in table 1). When the consultation manufacturer simultaneously exists multi-component sulfide gas, interference can be caused to sulfur dioxide and a sulfur dioxide chemical sensor, so that deviation of detection results can occur, the interference can not be eliminated, and other methods are suggested to be adopted for detection. In order to accurately measure the component content of the mixed gas, prevent safety and environmental protection accidents, personnel pay attention to improving the on-site sulfide gas detection accuracy of the device, and ensure that the accuracy of the whole test data can reach the industry standard.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a method for detecting the content of sulfur dioxide and hydrogen sulfide gas in mixed gas aiming at the defects.
The technical scheme of the invention is as follows: a method for detecting the content of sulfur dioxide and hydrogen sulfide in mixed gas.
The method adopts a two-step method to measure the accurate content of each component in the mixed gas;
first, the principle of oxidation-reduction reaction is used for measuring the total sulfur content in the mixed gas: absorbing the mixed gas by zinc acetate solution, dissolving the precipitate generated by the reaction by acid, and then mixing with a certain amount of I 2 The standard solution undergoes oxidation-reduction reaction, and excessive I 2 With Na 2 S 2 O 3 Titration of the solution according to Na 2 S 2 O 3 Obtaining total sulfur content in the liquid according to the standard liquid consumption;
secondly, sulfur content is measured by turbidimetry: and absorbing the mixed gas through a copper sulfate solution, generating copper sulfide precipitate at the moment, determining the content of sulfur in the hydrogen sulfide by the precipitate, subtracting the content of sulfur in the hydrogen sulfide from the total sulfur content, obtaining the content of sulfur dioxide in the mixed gas, and finally obtaining the accurate contents of the hydrogen sulfide and the sulfur dioxide by calculation.
The relevant reaction formula is:
further, the specific steps of the first step are as follows:
(1) Absorption: measuring 50mL of zinc acetate absorption liquid, injecting the zinc acetate absorption liquid into two serially connected gas washing cylinders, connecting the two gas washing cylinders by using emulsion tubes, checking the gas tightness before ventilation, rotating a T-shaped three-way plug to open to the atmosphere, exhausting for about 2min, exhausting residual gas and water in the pipe, passing through the gas washing cylinders at a flow rate of 500-1000 mL/min, and carrying out gas washing according to H 2 The S content determines the gas taking amount and is generally absorbed to 0.85-35 mgH 2 S, stopping ventilation and recording the reading of the flowmeter, the temperature and the pressure at the same time.
(2) Titration: the gas washing bottle is disassembled, the absorption liquid in the two bottles is transferred into a 500mL iodine measuring bottle, the absorption liquid is washed by water for a plurality of times in the iodine measuring bottle, 10mL of 0.1mol/L iodine standard liquid and 5mL of 1+1 hydrochloric acid are added, the mixture is shaken uniformly, covered and sealed, the mixture is placed in a dark place for 5 minutes, 0.1mol/L sodium thiosulfate standard solution is used for titration of light yellow, 5g/L starch and 1mL of starch are added, and the titration is carried out until the blue disappears as an end point.
(3) Blank test: the same volume of iodine absorbing solution was taken as a blank test according to 5.2.
(4) And (3) calculating results:
wherein:
c-sodium thiosulfate standard titration solution concentration, mol/L;
V 1 -the sample gas titrates to consume the volume, mL, of the standard titration solution of sodium thiosulfate;
V 0 blank test consumes sodium thiosulfate standard titration solution volume, mL;
v-sample volume, L;
16.02-a sulfur-sulfide conversion relationship;
22.4-molar volume of sulfide, L/mol under standard conditions;
0.65-converted mg/m 3 Sulfide is the coefficient of ppm sulfide;
0.94-the conversion coefficient of sulfide and sulfur;
f-the conversion coefficient of the sample gas volume under the standard state.
f=[(p+b-w)/101.3]*[273/(273+t)]*f 0
Wherein:
p-atmospheric pressure during sampling, KPa;
b-gas pressure during sampling, KPa;
w-saturated steam pressure at t ℃, KPa;
t-average temperature of sample gas (average temperature of flow meter at beginning and last two times);
f 0 -gas flow meter correction factor.
Further, the calibration method used in the second step comprises the following steps: in a 250mL iodometric bottle, 20.00 mL of iodine standard solution is added, 100 mL of standard solution is added, then 5mL of glacial acetic acid is added, shaking is carried out, standing is carried out, 0.01mol/L sodium thiosulfate is used for titration until the color is light yellow, 1mL of 0.5% starch solution is added until the color is blue, and then titration is continued until the color is just faded, namely, the end point is reached (sulfur is generated at the moment, the solution is slightly turbid, and special attention is paid to the mutation of the color of the titration end point). Recording the volume V of the sodium thiosulfate standard solution used 1 (ml). Simultaneously taking 100 ml of distilled water for blank titration, recording the volume V of the sodium thiosulfate standard solution used for blank titration 2 Milliliters;
hydrogen sulfide solution concentration (micrograms/milliliter) = [ (V2-V1) ×c×17.04 ]/100.
The sampling method used in the second step is as follows:
a large-scale packed absorption tube containing 10ml of absorption liquid and 0.1 ml of gelatin concentrated liquid is used, the absorption is carried out for 10-15 minutes at the flow rate of 0.5-1 liter/min, and the turbidimetric measurement is carried out on the same day after the sampling.
And a second step of analysis:
(1) Drawing a standard curve, and preparing a standard color column tube according to the following table
| Pipe number | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
| Absorption liquid (milliliter) | 10.0 | 9.0 | 8.8 | 8.6 | 8.4 | 8.2 | 8.0 |
| Standard solution (milliliter) | 0 | 1.0 | 1.2 | 1.4 | 1.6 | 1.8 | 2.0 |
| Hydrogen sulfide content (micrograms) | 0 | 5 | 6 | 7 | 8 | 9 | 10 |
After adding 0.1 ml of gelatin solution to each tube, capping, mixing, adding standard solution, shaking, and measuring optical density at wavelength of 450nm with a 2 cm cuvette. Drawing a standard curve according to the optical density and the content (micrograms) of hydrogen sulfide;
(3) Sample measurement: after sampling, shaking the absorption liquid uniformly, and directly measuring the optical density and checking a standard curve to obtain the content (micrograms) of hydrogen sulfide;
and (3) calculating: c (H) 2 S）=a/V 0 ,C（S）=0.94*a/V 0
C(H 2 S) - - - - -Hydrogen sulfide concentration, mg/cubic meter
a- -hydrogen sulfide content, micrograms
V 0 Conversion to sample volume under standard conditions
0.94- -conversion of Hydrogen sulfide content to Sulfur content relation coefficient
(3) And (3) calculating: c (sulfur dioxide) = [ S All-around (mg/L)-C（S，mg/L）]*2 。
The invention has the beneficial effects that: hydrogen sulfide is colorless, odorless and extremely toxic harmful gas, poisoning can be caused after inhalation, the harmful gas can be damaged to different degrees, sulfur dioxide is also extremely odorous and colorless gas, the harmful gas can be damaged to different degrees after inhalation, and the two gases are mixed together, so that people can not recognize the specific content of the harmful gas, and potential safety hazards are brought. The method can detect the specific content of the hydrogen sulfide and the sulfur dioxide gas, is convenient to make timely precautions, avoids the occurrence of safety accidents, can control the emission of sulfur dioxide and the toxic and harmful gas of the hydrogen sulfide, avoids the occurrence of environmental protection accidents, and plays an important role in factory production.
Detailed Description
A method for measuring the content of each component in the mixed gas of sulfur dioxide and hydrogen sulfide adopts a two-step method for measurement,
the first step: the principle of oxidation-reduction reaction is to measure the total sulfur content in the mixed gas:
1. materials and reagents
Iodine standard titration solution: c (1/2I) 2 ）=0.1mol/L；
Standard titration solution of sodium thiosulfate: c (Na) 2 S 2 O 3 ）=0.1mol/L；
Hydrochloric acid solution: 1+1;
starch indicator: 5g/L;
zinc acetate absorption liquid (40 g/L): 40g of zinc acetate was weighed and dissolved in distilled water, 10mL of glacial acetic acid was added, and the mixture was diluted to 1000mL with distilled water.
2. Instrument for measuring and controlling the intensity of light
Gas-absorbing bottle: monte or Techner 250mL;
iodine flask: 500mL;
a wet gas flow meter 5L, an index value of 20mL.
3. Analytical procedure
(1) Absorption: measuring 50mL of zinc acetate absorption liquid, injecting the zinc acetate absorption liquid into two serially connected gas washing cylinders, connecting the two gas washing cylinders by using emulsion tubes, checking the gas tightness before ventilation, rotating a T-shaped three-way plug to open to the atmosphere, exhausting for about 2min, exhausting residual gas and water in the pipe, passing through the gas washing cylinders at a flow rate of 500-1000 mL/min, and carrying out gas washing according to H 2 S contentThe gas taking amount is determined and is generally absorbed to 0.85 to 35. 35mgH 2 S, stopping ventilation and recording the reading of the flowmeter, the temperature and the pressure at the same time.
(2) Titration: the gas washing bottle is disassembled, the absorption liquid in the two bottles is transferred into a 500mL iodine measuring bottle, the absorption liquid is washed by water for a plurality of times in the iodine measuring bottle, 10mL of 0.1mol/L iodine standard liquid and 5mL of 1+1 hydrochloric acid are added, the mixture is shaken uniformly, covered and sealed, the mixture is placed in a dark place for 5 minutes, 0.1mol/L sodium thiosulfate standard solution is used for titration of light yellow, 5g/L starch and 1mL of starch are added, and the titration is carried out until the blue disappears as an end point.
(3) Blank test: the same volume of iodine absorbing solution was taken as a blank test according to 5.2.
(4) And (3) calculating results:
in mg/m 3 The total S content in the sample is calculated according to the following formula:
S all-around (mg/m 3 )=[16.02*(V 0 -V 1 )]*1000C/V*f
In ppm (w/w), calculated as:
S all-around (mg/L)=0.65*S All-around (mg/m 3 )
Calculated as volume percent (v/v%) as follows:
S all-around (%)=0.65*S All-around (mg/m 3 )*0.0001
=[C(V 0 -V 1 )*22.4*100*0.94]/2Vf*1000=[C(V 0 -V 1 )*1.05]/Vf
Wherein:
c-sodium thiosulfate standard titration solution concentration, mol/L;
V 1 -the sample gas titrates to consume the volume, mL, of the standard titration solution of sodium thiosulfate;
V 0 blank test consumes sodium thiosulfate standard titration solution volume, mL;
v-sample volume, L;
16.02-a sulfur-sulfide conversion relationship;
22.4-molar volume of sulfide, L/mol under standard conditions;
0.65-conversion of mg/m 3 Sulfide is the coefficient of ppm sulfide;
0.94-the conversion coefficient of sulfide and sulfur;
f-the conversion coefficient of the sample gas volume under the standard state.
f=[(p+b-w)/101.3]*[273/(273+t)]*f 0
Wherein:
p-atmospheric pressure during sampling, KPa;
b-gas pressure during sampling, KPa;
w-saturated steam pressure at t ℃, KPa;
t-average temperature of sample gas (average temperature of flow meter at beginning and last two times);
f 0 -gas flow meter correction factor.
And a second step of: turbidimetric sulfur content measurement
1. Instrument: large-scale packet-type absorption tube; the flow range of the sampler is 0-2 liters/min; a spectrophotometer.
2. Reagent(s)
Absorption liquid: 1/1000 of copper sulfate solution.
Gelatin solution: weigh the gram of gelatin and dilute to 100 milliliters with water.
C（1/2I 2 ) Standard solution of iodine of =0.01 μg/ml
C（Na 2 S 2 O 3 ) Standard solution of sodium thiosulfate of =0.01 μg/ml
Standard solution: taking sodium sulfide crystal, flushing the surface with a small amount of water, then rapidly weighing about 0.2 g of the sodium sulfide crystal, dissolving in distilled water, transferring the solution into a 500ml brown volumetric flask, diluting to a scale, and obtaining C (H) 2 S) is about 5 μg/ml. Since S is extremely unstable in aqueous solution, a standard curve should be made immediately after dilution.
3. The calibrating method comprises the following steps: adding 20.00 mL of iodine standard solution into a 250mL iodine measuring flask, adding 100 mL of standard solution, adding 5mL of glacial acetic acid, shaking, standing, titrating to light yellow with 0.01mol/L sodium thiosulfate, adding 1mL of 0.5% starch solution to be blue, and then continuing to titrate until the blue color just fades, thus obtaining the final productThe spot (in this case sulphur formation, which makes the solution slightly turbid, special attention should be paid to the abrupt change in colour at the end of titration). Recording the volume V of the sodium thiosulfate standard solution used 1 (ml). Simultaneously taking 100 ml of distilled water for blank titration, recording the volume V of the sodium thiosulfate standard solution used for blank titration 2 Milliliters.
Hydrogen sulfide solution concentration (micrograms/milliliter) = [ (V2-V1) ×c×17.04]/100
4. Sampling
A large-scale packed absorption tube containing 10ml of absorption liquid and 0.1 ml of gelatin concentrated liquid is used, the absorption is carried out for 10-15 minutes at the flow rate of 0.5-1 liter/min, and the turbidimetric measurement is carried out on the same day after the sampling.
5. Analytical procedure
(1) Drawing a standard curve, and preparing a standard color column tube according to the following table
| Pipe number | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
| Absorption liquid (milliliter) | 10.0 | 9.0 | 8.8 | 8.6 | 8.4 | 8.2 | 8.0 |
| Standard solution (milliliter) | 0 | 1.0 | 1.2 | 1.4 | 1.6 | 1.8 | 2.0 |
| Hydrogen sulfide content (micrograms) | 0 | 5 | 6 | 7 | 8 | 9 | 10 |
After adding 0.1 ml of gelatin solution to each tube, capping, mixing, adding standard solution, shaking, and measuring optical density at wavelength of 450nm with a 2 cm cuvette. A standard curve was drawn with optical density versus hydrogen sulfide content (micrograms).
(2) Sample measurement: after sampling, the absorption liquid is shaken uniformly, the optical density can be directly measured, and the standard curve is checked to obtain the content (micrograms) of hydrogen sulfide.
And (3) calculating: c (H) 2 S）=a/V 0 ,C（S）=0.94*a/V 0
C(H 2 S) - - - - -hydrogen sulfide concentration, mg/cubic meter.
a- -hydrogen sulfide content, micrograms.
V 0 -converted to sample volume under standard conditions.
0.94- - -the hydrogen sulfide content is converted to a sulfur content relationship coefficient.
(3) Notice matters
During sampling, gelatin solution is added into the absorption liquid. The standard solution is extremely unstable, and a standard curve should be made immediately after calibration.
(4) And (3) calculating: c (sulfur dioxide) = [ S All-around (mg/L)-C（S，mg/L）]*2
Example 1
Method for measuring content of hydrogen sulfide in mixed gas in turbidimetric mode in two-step method
Detection data (shown in Table 1) of hydrogen sulfide in mixed gas with different sampling volumes on site by using a turbidimetric method in a two-step method
TABLE 1 determination of H in a gas mixture of different sample volumes by turbidimetric method in a two-step method 2 S gas content
As can be seen from the detection conditions, the sample analysis of the mixed gas on site of the device by the turbidimetric method can see that the measurement results of different sampling volumes are different, but the batch sample H 2 The relative standard deviation of the S detection result is less than or equal to 10 percent. Meets the air and exhaust gas monitoring standard requirements.
Example 2
The detection data of hydrogen sulfide in mixed gas with different sampling volumes on site of the turbidimetry measuring device are as follows:
TABLE 2 determination of H in Mixed gas with different sample volumes by turbidimetric method 2 S gas content
As can be seen from the detection conditions, the device is assembled in a turbidimetric mannerThe analysis of the content of the hydrogen sulfide gas in the mixed gas sample in the site can show that the measurement results of different sampling volumes are different, but the batch of samples H 2 The relative standard deviation of the S detection result is less than or equal to 10 percent. Meets the air and exhaust gas monitoring standard requirements.
Example 3
Two-step method for measuring sulfur dioxide and hydrogen sulfide gas content in on-site mixed gas of device (shown in table 3)
Table 3 two-step method for determining sulfur dioxide and hydrogen sulfide gas content in mixed gas in site of apparatus
| Sequence number | Detection method | Sampling point | Total sulfur content (ppm) | Hydrogen sulfide gas content (PPM) | Sulfur dioxide gas detection results (%) |
| 1 | Oxidation-reduction method | Device site | 1014.8 | 4.0 | 0.2022 |
| 2 | Oxidation-reduction method | Device site | 981.6 | 4.1 | 0.1959 |
| 3 | Oxidation-reduction method | Device site | 1016.6 | 4.2 | 0.2029 |
| 4 | Oxidation-reduction method | Device site | 1064.9 | 4.2 | 0.2122 |
| 5 | Oxidation-reduction method | Device site | 1107.1 | 4.4 | 0.2102 |
As can be seen from the detection conditions, SO in the gas sample is mixed in the field of the device by a two-step method 2 And (3) analyzing the gas content to obtain different detection results of different sampling volumes.
Example 4
Two-step method for measuring content detection data of each component in mixed gas
(1) The two standard gases of low concentration sulfur dioxide and hydrogen sulfide were mixed and measured by a two-step method, wherein the concentration of the sulfur dioxide gas was 9.44ppm and the concentration of the hydrogen sulfide gas was 10.00ppm, and the detection conditions are shown in Table 4.
Table 4 two-step method for determining sulfur dioxide and hydrogen sulfide content in low concentration standard gas mixture
From the table, the mixed gas of the low-concentration sulfur dioxide standard gas and the hydrogen sulfide standard gas is detected by adopting a two-step method, the total sulfur content in the mixed gas is detected by the first step, the hydrogen sulfide gas content in the mixed gas is detected by the second step, and the contents of the sulfur dioxide and the hydrogen sulfide gas in the mixed gas can be obtained by calculation and are respectively matched with the concentrations of the added sulfur dioxide and the hydrogen sulfide standard gas, the measurement errors are less than or equal to +/-5%, and the JJG693-2011 standard verification requirement is met. Fully illustrates that the two-step method is suitable for measuring the content of each component of the hydrogen sulfide and the sulfur dioxide in the mixed gas.
Example 5
(1) The two standard gases of high concentration sulfur dioxide and hydrogen sulfide were mixed and measured by a two-step method, wherein the concentration of the sulfur dioxide gas was 317.1ppm and the concentration of the hydrogen sulfide gas was 35.00ppm, and the detection conditions are shown in Table 5.
TABLE 5 detection results of sulfur dioxide and hydrogen sulfide in high concentration standard gas mixture
From the table, the mixed gas of the high-concentration sulfur dioxide standard gas and the hydrogen sulfide standard gas is detected by adopting a two-step method, the total sulfur content in the mixed gas is detected by the first step, the hydrogen sulfide gas content in the mixed gas is detected by the second step, and the contents of the sulfur dioxide and the hydrogen sulfide gas in the mixed gas can be obtained by calculation and are respectively matched with the concentrations of the added sulfur dioxide and the hydrogen sulfide standard gas, the measurement errors are less than or equal to +/-5%, and the JJG693-2011 verification regulation requirement is met. Fully illustrates that the two-step method is suitable for measuring the content of each component of the hydrogen sulfide and the sulfur dioxide in the mixed gas.
As can be seen from the above examples: the method is characterized in that the method comprises the steps of mixing standard gases on site, detecting the content of hydrogen sulfide and sulfur dioxide gases in mixed gases with different sampling volumes by a two-step method, and obtaining different results, wherein the relative standard deviation of the detection results of samples in batches is less than or equal to 10%, so that the requirements of air and waste gas monitoring standards are met. The content of hydrogen sulfide and sulfur dioxide in the mixed gas is analyzed, so that the accurate result of grasping the content of each component is achieved, and the detection target can be realized by adopting a two-step method.
Claims (9)
1. A method for measuring the content of sulfur dioxide and hydrogen sulfide in mixed gas is characterized in that the method adopts a two-step method to measure the accurate content of each component in the mixed gas;
first, the principle of oxidation-reduction reaction is used for measuring the total sulfur content in the mixed gas: absorbing the mixed gas by zinc acetate solution, dissolving the precipitate generated by the reaction by acid, and then mixing with a certain amount of I 2 The standard solution undergoes oxidation-reduction reaction, and excessive I 2 With Na 2 S 2 O 3 Titration of the solution according to Na 2 S 2 O 3 Obtaining total sulfur content in the liquid according to the standard liquid consumption;
step two, sulfur content is measured in a turbidimetry mode: and absorbing the mixed gas through a copper sulfate solution, generating copper sulfide precipitate at the moment, determining the content of sulfur in the hydrogen sulfide by the precipitate, subtracting the content of sulfur in the hydrogen sulfide from the total sulfur content, obtaining the content of sulfur dioxide in the mixed gas, and finally obtaining the accurate contents of the hydrogen sulfide and the sulfur dioxide by calculation.
2. The method for determining the sulfur dioxide and hydrogen sulfide gas content of a mixed gas according to claim 1, wherein the reagents used in the first step are as follows:
(1) Iodine standard titration solution: c (1/2I) 2 ）=0.1mol/L；
(2) Standard titration solution of sodium thiosulfate: c (Na) 2 S 2 O 3 ）=0.1mol/L；
(3) Hydrochloric acid solution: 1+1;
(4) Starch indicator: 5g/L;
(5) Zinc acetate absorption liquid (40 g/L): 40g of zinc acetate was weighed and dissolved in distilled water, 10mL of glacial acetic acid was added, and the mixture was diluted to 1000mL with distilled water.
3. The method for measuring the sulfur dioxide and hydrogen sulfide gas contents in a mixed gas according to claim 1, wherein the apparatus for the first step comprises the following steps:
(1) Gas-absorbing bottle: monte or Techner 250mL;
(2) Iodine flask: 500mL;
(3) A wet gas flow meter 5L, an index value of 20mL.
4. The method for determining the sulfur dioxide and hydrogen sulfide gas content in a mixed gas according to claim 1, wherein the first step comprises the following specific steps:
(1) Absorption: measuring 50mL of zinc acetate absorption liquid, injecting the zinc acetate absorption liquid into two serially connected gas washing cylinders, connecting the two gas washing cylinders by using emulsion tubes, checking the gas tightness before ventilation, rotating a T-shaped three-way plug to open to the atmosphere, exhausting for about 2min, exhausting residual gas and water in the pipe, passing through the gas washing cylinders at a flow rate of 500-1000 mL/min, and carrying out gas washing according to H 2 The S content determines the gas taking amount and is generally absorbed to 0.85-35 mgH 2 S, stopping ventilation when the temperature and pressure of the flowmeter are required to be recorded simultaneously;
(2) Titration: the gas washing bottle is disassembled, the absorption liquid in the two bottles is transferred into a 500mL iodine measuring bottle, the two bottles are washed by water for a plurality of times, 10mL of 0.1mol/L iodine standard liquid and 5mL of 1+1 hydrochloric acid are added, the mixture is shaken uniformly, covered and sealed, the mixture is placed in a dark place for 5 minutes, 0.1mol/L sodium thiosulfate standard solution is used for titrating light yellow, 5g/L starch and 1mL of starch are added, and the titration is carried out until the blue color disappears as an end point;
(3) Blank test: taking iodine absorption liquid with the same volume as that of the iodine absorption liquid according to 5.2 for blank test;
(4) And (3) calculating results:
in mg/m 3 Indicating the total S content in the gas sampleThe following formula is calculated:
S all-around (mg/m 3 )=[16.02*(V 0 -V 1 )]*1000C/V*f
In ppm (w/w), calculated as:
S all-around (mg/L)=0.65*S All-around (mg/m 3 )
Calculated as volume percent (v/v%) as follows:
S all-around (%)=0.65*S All-around (mg/m 3 )*0.0001
=[C(V 0 -V 1 )*22.4*100*0.94]/2Vf*1000=[C(V 0 -V 1 )*1.05]/Vf
Wherein:
c-sodium thiosulfate standard titration solution concentration, mol/L;
V 1 -the sample gas titrates to consume the volume, mL, of the standard titration solution of sodium thiosulfate;
V 0 blank test consumes sodium thiosulfate standard titration solution volume, mL;
v-sample volume, L;
16.02-a sulfur-sulfide conversion relationship;
22.4-molar volume of sulfide, L/mol under standard conditions;
0.65-converted mg/m 3 Sulfide is the coefficient of ppm sulfide;
0.94-the conversion coefficient of sulfide and sulfur;
f-the conversion coefficient of the sample gas volume in the standard state;
f=[(p+b-w)/101.3]*[273/(273+t)]*f 0
wherein:
p-atmospheric pressure during sampling, KPa;
b-gas pressure during sampling, KPa;
w-saturated steam pressure at t ℃, KPa;
t-average temperature of sample gas (average temperature of flow meter at beginning and last two times);
f 0 -gas flow meter correction factor.
5. The method for measuring the sulfur dioxide and hydrogen sulfide gas contents in the mixed gas according to claim 1, wherein the apparatus used in the second step:
(1) Large-scale packet-type absorption tube;
(2) The flow range of the sampler is 0-2 liters/min;
(3) A spectrophotometer.
6. The method for measuring the sulfur dioxide and hydrogen sulfide gas contents in a mixed gas according to claim 1, wherein the reagent used in the second step:
(1) Absorption liquid: 1/1000 of copper sulfate solution;
(2) Gelatin solution: weighing the gram of gelatin, and diluting the gelatin to 100 milliliters with water;
（3） C（1/2I 2 ) =0.01 μg/ml iodine standard solution;
（4） C（Na 2 S 2 O 3 ) =0.01 μg/ml sodium thiosulfate standard solution;
(5) Standard solution: taking sodium sulfide crystal, flushing the surface with a small amount of water, then rapidly weighing about 0.2 g of the sodium sulfide crystal, dissolving in distilled water, transferring the solution into a 500ml brown volumetric flask, diluting to a scale, and obtaining C (H) 2 S) about 5 μg/ml; since S is extremely unstable in aqueous solution, a standard curve should be made immediately after dilution.
7. The method for measuring the sulfur dioxide and hydrogen sulfide gas contents in a mixed gas according to claim 1, wherein the calibration method used in the second step comprises: in a 250mL iodometric bottle, 20.00 mL of iodine standard solution is added, 100 mL of standard solution is added, then 5mL of glacial acetic acid is added, shaking is carried out, standing is carried out, 0.01mol/L sodium thiosulfate is used for titration until the color is light yellow, 1mL of 0.5% starch solution is added until the color is blue, and then titration is continued until the color is just faded, namely, the end point is reached (sulfur is generated at the moment, the solution is slightly turbid, and special attention is paid to the mutation of the color of the titration end point). Recording the volume V of the sodium thiosulfate standard solution used 1 (ml). Simultaneously taking 100 ml of distilled water for blank titration, recording the volume V of the sodium thiosulfate standard solution used for blank titration 2 Milliliters;
hydrogen sulfide solution concentration (micrograms/milliliter) = [ (V2-V1) ×c×17.04 ]/100.
8. The method for measuring the sulfur dioxide and hydrogen sulfide gas contents in a mixed gas according to claim 1, wherein the sampling method used in the second step comprises:
a large-scale packed absorption tube containing 10ml of absorption liquid and 0.1 ml of gelatin concentrated liquid is used, the absorption is carried out for 10-15 minutes at the flow rate of 0.5-1 liter/min, and the turbidimetric measurement is carried out on the same day after the sampling.
9. The method for measuring the sulfur dioxide and hydrogen sulfide gas contents in a mixed gas according to claim 1, wherein the analyzing step of the second step:
(1) Drawing a standard curve, and preparing a standard color column tube according to the following table
After adding 0.1 ml of gelatin solution to each tube, capping, mixing, adding standard solution, shaking, and measuring optical density at wavelength of 450nm with a 2 cm cuvette. Drawing a standard curve according to the optical density and the content (micrograms) of hydrogen sulfide;
(2) Sample measurement: after sampling, shaking the absorption liquid uniformly, and directly measuring the optical density and checking a standard curve to obtain the content (micrograms) of hydrogen sulfide;
and (3) calculating: c (H) 2 S）=a/V 0 ,C（S）=0.94*a/V 0
C(H 2 S) - - - - -Hydrogen sulfide concentration, mg/cubic meter
a- -hydrogen sulfide content, micrograms
V 0 Conversion to sample volume under standard conditions
0.94- -conversion of Hydrogen sulfide content to Sulfur content relation coefficient
(3) And (3) calculating: c (sulfur dioxide) = [ S All-around (mg/L)-C（S，mg/L）]*2 。
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