Sampling position ãããããããããããããããããããããããããããããããããããããããããããããã4
When selecting a sampling position for representative gas, ensure it is located where air and dust ingress is minimized, and the flue gas flow is uniform, avoiding curves and sudden changes in shape The site should allow for safe and easy sampling, potentially requiring scaffolding for accessibility The sampling opening must accommodate a gas sampling tube inserted at a right angle to the flue gas flow and be constructed from materials that can withstand temperatures up to 120°C Additionally, the opening should have a cover to prevent flue gas spouting and air ingress when not in use, with precautions taken to avoid burns and hazards during cover removal.
Sampling gas apparatus and instrument ãããããã4
The gas sampling apparatus must meet specific criteria to ensure accurate results The sampling tubes and connecting tubing should be made from corrosion-resistant materials such as borosilicate glass, silica glass, or fluoroethylene resin, to withstand hydrogen sulfide exposure in flue gas To prevent dust contamination, the sampling tube's end should be sealed with a filter medium like silica wool or sintered glass Tubing should be kept as short as possible to minimize moisture condensation and should be heated to 120°C, unless condensation is not a concern Additionally, a washing bottle, as depicted in figure 1, must be utilized, and the entire setup should be positioned in an area shielded from direct sunlight.
Constitution of gas sampling apparatus and sampling procedure ããããããããããããããããããã4
The constitution of gas sampling apparatus and sampling procedure for respective analysis methods shall be as follows
6.3.1.1 Gas sampling apparatus and instruments
An example of the gas sampling apparatus to be used in gas chromatography is shown in figure 1
A: Gas sampling tube B: Filtering material C: Three-way cock D: Conduit tube
A 50 ml of sodium hydroxide solution (200 giL)]
F: Suction pump (for replacing exhaust of gas flow path)
Figure 1 Example of gas sampling apparatus
Reagents used for the washing solution of the gas sampling apparatus shall be as follows a) Sodium hydroxide, specified in JIS K 8576 b) Phosphoric acid, specified in JIS K 9005
To prepare the washing solution, dissolve 200 g of sodium hydroxide in water to create a 1 L solution for the washing bottle (E) Additionally, for the gas collecting container, mix 5.5 g of phosphoric acid with water to achieve a total volume of 1 L.
In gas chromatography, the sample gas collection container, as shown in Figure 1, can be utilized in various ways One method involves injecting the sample gas into the gas chromatograph immediately after it is collected.
The gas sampling syringe, available in capacities ranging from 1 ml to 5 ml and constructed from glass, features an interior surface designed to minimize adsorption Prior to use, the syringe must be cleaned with phosphoric acid as outlined in section 6.3.1.3 b), followed by thorough washing with water and drying.
`,`,,,,`,``,````,``````,,,`,-`-`,,`,,`,`,,` - b) In the case where the sample gas (sample in laboratory) carried to a labo- ratory is injected into gas chromatograph
A gas sampling bag, typically with a capacity of 1 liter or more, is constructed from materials such as polyester resin and fluoroethylene resin, which are designed to minimize the adsorption or absorption of gas components However, this method is not ideal for long-term storage of sample gases.
A gas collecting bottle, typically a 1-liter glass container as shown in JIS K 0095 figure 4, must be properly cleaned prior to use This involves treating the bottle with phosphoric acid as specified in section 6.3.1.3 b), followed by thorough washing with water and drying to ensure it is free of contaminants.
Gas collectors made of stainless steel, with a capacity of 1 liter or more, feature an electrolytically polished interior surface that is treated with silica-coating for inactivation Additionally, these collectors are equipped with a shut-off cock that ensures the gas flow path's interior surface is also inactivated.
The gas sampling procedure in the case of gas chromatography shall be as follows
Before operating the suction pump (F), ensure that the gas flow path of the gas sampling tube (A) and filtering material (B) is adequately replaced with sample gas For gas sampling using a syringe, connect it to the conduit tube (D) of the apparatus, open the three-way cock (C), and pump the syringe multiple times to replace the gas in the flow path before sampling After collecting the sample gas, close the three-way cock (C), detach the syringe, and retain it for analysis Alternatively, when using a gas sampling bag, connect the bag (H) inside an acrylic resin airtight container (I) to the conduit tube (D), open the three-way cock (C), and operate the suction pump (L) while opening shut-out cocks (J) and (K) to collect the sample gas Once collected, close the shut-out cock (J) and the three-way cock (C), stop the suction pump (L), remove the gas sampling bag (H) from the container, seal it tightly, and keep it for analysis.
A: Gas sampling tube D: Conduit tube H: Gas sampling bag
Figure 2 Example of gas sampling apparatus using gas sampling bag c) In the case of gas collecting bottle
To create a vacuum for gas sampling, connect the vacuumed gas collecting bottle to the conduit tube (D) of the gas sampling apparatus as outlined in JIS K 0095 sections 7.4.2 and 7.4.5 a) Open the three-way cock (C) and the shut-off cock of the gas collecting bottle to suction the sample gas Once the sample is collected, close both the three-way cock and the shut-off cock, then detach the gas collecting bottle for analysis.
To replace the air with sample gas in the gas sampling apparatus, connect a gas collecting bottle between the three-way cock (C) and the washing bottle (E) Open the three-way cock and the shut-out cock of the gas collecting bottle, then use the suction pump (F) to absorb the sample gas, ensuring that the volume of gas is at least ten times that of the gas sampling tube and associated components Once the air in the bottle has been replaced with sample gas, close both the shut-out cock and the three-way cock, stop the suction pump, and then detach the gas collecting bottle to obtain the sample for analysis.
To collect gas samples, first connect a pre-vacuumed gas collecting can to the conduit tube (D) of the gas sampling apparatus Open the three-way cock (C) and the switching valve of the gas collecting can to suction the sample gas After suctioning, close the three-way cock (C) and the shut-out cock of the collecting can Finally, detach the gas collecting can to take the sample gas for analysis.
6.3.2 In the case of methylene blue absorptiometry and ion selective electrode method
6.3.2.1 Apparatus and instruments for sampling gas
For gas sampling apparatus and absorbing bottles utilized in methylene blue absorptiometry and the ion selective electrode method, the appropriate equipment should be selected based on the volume of sample gas being analyzed.
For gas sampling of 1 liter or more, a suitable gas sampling apparatus is illustrated in Figure 3, while an example of an absorbing bottle is depicted in Figure 4.
Gas sampling tube M: Absorbing bottle
Filtering material N: Trap (packed with
Three-way cock glass wool)
Conduit tube S: Wet gas meter
Washing bottle (containing 50 ml T: Thermometer of washing solution) P: Manometer
Suction pump (1 L/min to 5 L/min) V: Flow rate controlling
Figure 3 Example of gas sampling apparatus Figure 4
When sampling gas amounts under 1 liter, it is essential to utilize appropriate equipment Figure 5 illustrates a gas sampling apparatus, while Figure 6 depicts the corresponding absorbing bottle designed for effective gas collection.
G: Heater L: Absorbing bottle P: Injector syringe (100 ml) Q: Absorbing bottle (1 L)
NOTE: Land Q are connected when using an absorbing bottle
Figure 5 Example of gas sampling apparatus
Figure 6 Example of absorbing bottle
6.3.2.2 Reagents for absorbing solution and washing solution
For the methylene blue absorptiometry and ion selective electrode method, the absorbing solution in bottle (M) and the washing solution in bottle (E) should include the following reagents: a) Zinc sulfate heptahydrate (JIS K 8953), b) Sodium hydroxide (JIS K 8576), c) Ammonium sulfate (JIS K 8960), d) Glycerin (JIS K 8925), e) Disodium dihydrogen ethylenediamine tetraacetate dihydrate (JIS K 8107), and f) L(+)-Ascorbic acid (JIS K 9502).
6.3.2.3 Method for preparation of absorbing solution and washing solution
To prepare the absorbing solutions for methylene blue absorptiometry and the ion selective electrode method, specific formulations are required For the methylene blue absorptiometry, dissolve 5 g of zinc sulfate pentahydrate in 500 ml of water, then add a solution of 6 g of sodium hydroxide dissolved in 300 ml of water, followed by 70 g of ammonium sulfate while stirring, ensuring the zinc hydroxide precipitate dissolves, and finally dilute to 1 L with water For the ion selective electrode method, combine 4 g of sodium hydroxide, 200 ml of glycerin, 4 g of disodium dihydrogen ethylenediaminetetraacetate dihydrate, and 10 g of L(+)-ascorbic acid in water, then add water to reach a total volume of 1 L The washing solution for the gas sampling apparatus should be prepared according to the specifications outlined in section 6.3.1.3 a).
In the case of gas chromatography ããããããããããããããã14
The gas sampling procedure shall be in accordance with 6.3.1.
In the case of methylene blue absorptiometry and ion selective
To prepare sample solutions for analysis, first collect the sample gas using the sampling apparatus depicted in Figures 3 or 5, as outlined in section 6.3.2.4 Once the sample gas is suctioned, carefully transfer the solution from the absorbing bottle for further analysis.
To prepare the sample solution for analysis, use a 200 ml volumetric flask if employing the absorbing bottle shown in figure 4, or a 20 ml volumetric flask for the bottle in figure 6 Rinse the interior of the absorbing bottle with the absorbing solution and combine the washings with the contents of the volumetric flask Finally, fill the flask to the mark with absorbing solution and seal it tightly.
Summaryããããããããããããããããããããããããããããããããããããããããããããããã ãããããããããããã14
Analysis of flue gas is conducted using either a packed column or a capillary column as the separation medium, paired with detectors such as a thermal conductivity detector, flame photometric detector, or atomic emission detector The gas sample is introduced into the gas chromatograph, allowing for the determination of hydrogen sulfide from the resulting chromatogram The detection ranges vary: for a thermal conductivity detector, it is 200 vol ppm to 20 vol % with a 100 µl sample; for a flame photometric detector, it ranges from 0.2 vol ppm to 50 vol ppm; and for an atomic emission detector, the range is 0.05 vol ppm to 50 vol ppm.
Reagents and gas
The following reagents and gas shall be used
8.2.2 Helium, with purity of 99.999 vol % min or 99.999 9 vol % min
8.2.3 Nitrogen, of Grade 1 or Grade 2 as specified in JIS K 1107
8.2.4 Argon, of Grade 1 or Grade 2 as specified in JIS K 1105
8.2.5 Hydrogen, of Grade 1 to Grade 3 as specified in JIS K 0512
8.2.6 Oxygen, with purity 99.5 vol % min as specified in JIS K 1101
8.2.7 High purity air, which is clean and dry
Apparatus and instruments
The following apparatus and instruments shall be used
The gas chromatograph's sample introducing instrument includes a gas sampling syringe for gas sampling apparatus and a loop injector, which consists of a sample loop tube connected to a rotary or sliding valve made of fluoroethylene resin, capable of withstanding temperatures up to 150°C For low concentration samples, the instrument should have an inner surface of inactivated stainless steel or fluoroethylene resin to minimize gas component adsorption An example of this gas sample introducing apparatus is illustrated in Figure 7.
Pressure control for injection opening
Figure 7 Example of gas sample introducing apparatus
To analyze the sample gas, connect the suction pump to position 3 (out) as indicated in figure 7 and fill the measuring tube with the gas Once the temperature and pressure stabilize, switch the valve to connect positions 1 and 2, as well as positions 5 and 6, to introduce the sample gas from the measuring tube into the gas chromatograph's injection opening.
8.3.2 Constitution of gas chromatograph The constitution of gas chromatograph shall be as follows a) Packed column, in accordance with the following 1), which is filled with anyone of column packings in 2)
A tube designed for column use must have its inner surface thoroughly cleaned with acid, followed by a rinse with phosphoric acid as specified in section 6.3.1.3 b) After this process, the tube should be washed with water and dried Alternatively, a tube made from fluoroethylene resin can also be utilized.
Note 3) When using a tube of fluoroethylene resin, make sure that the con- nection is without any leakage of gas
Distributor type packing is created by impregnating high-purity diatomaceous earth or inert material beads, ranging from 74 to 250 micrometers in diameter, with a suitable stationary liquid, such as 1,2,3-tris(2-cyanoethoxy)propane, as outlined in Table 4 of JIS K 0114.
Note 4) The particles of terephthalic acid, particles of fluoroethylene resin, etc
Porous polymer packing, made from organic high polymer compounds, offers excellent chemical stability and mechanical strength The capillary column features a tube whose interior surface is chemically bonded with a stationary liquid or stabilized with an adsorbent, ensuring optimal performance in various applications.
1) Tube for column, a tube based on molten silica or a tube of stainless steel of which the inside surface is inactivated
2) Stationary liquid, of methyl silicone, or methyl silicone in which a part of methyl group is replaced by another functional group (for example, phenyl group) or polyethylene glycol
Adsorbents made from silicon oxide, aluminum oxide, or organic high polymer compounds offer excellent chemical stability and mechanical strength Additionally, various detectors such as thermal conductivity detectors, flame photometric detectors, and atomic emission detectors are utilized in analytical applications.
In certain atomic emission detectors, the use of a packed column is not feasible For thermal conductivity detectors, the appropriate carrier gases include helium (8.2.2), nitrogen (8.2.3), or argon (8.2.4) In the case of flame photometric detectors, helium (8.2.2) or nitrogen (8.2.3) is recommended, while atomic emission detectors require helium (8.2.2) with a minimum purity of 99.9999 vol % Each detector has specific gas requirements that must be adhered to for optimal performance.
1) Addition gas for thermal conductivity detector, the same kind of gas as the carrier gas
2) Flame photometric detector The gas for flame photometric detector shall be selected from among the followings given according to each usage
2.1) Addition gas, helium in 8.2.2 or nitrogen in 8.2.3
2.2) Combustion gas, hydrogen specified in 8.2.5
2.3) Supporting gas, oxygen in 8.2.6 or high purity air in 8.2.7
3) Atomic emission detector The gas for atomic emission detector shall be as follows
3.1) Addition gas (purge gas), nitrogen in 8.2.3
3.2) Combustion gas (plasma gas), helium in 8.2.2, with purity of 99.999 9 vol % mIn
3.3) Supporting gas, hydrogen of Grade 2 or superior in 8.2.5 and oxygen in 8.2.6, with purity of 99.999 vol % min.
Introduction of sample gas for analysis into gas chromatography ãããããããããããããããã17
To analyze sample gas using a gas chromatograph, there are two methods for introducing the gas The first method involves using a gas sampling syringe, where a needle is attached to the syringe to directly introduce the sample gas into the chromatograph If the gas is collected in a bag or bottle, the container's opening should be sealed, and the syringe needle should penetrate the stopper to transfer the gas The second method utilizes a gas sample introducing apparatus In this case, connect the gas sampling bag or bottle to the apparatus, open the container's valve, and use a pump to suction enough sample gas—at least five times the measuring tube's capacity—until the tube is filled Finally, switch the valve on the apparatus to introduce the sample gas into the gas chromatograph for analysis.
To facilitate gas analysis, connect the sample injection opening of the gas sampling apparatus shown in Figure 7 to the sample gas sampling tube (A) depicted in Figure 1 This setup allows for the direct introduction of the sample gas into a gas chromatograph for precise analysis.
Operation conditions of gas chromatograph
8.5.1 Conditions of sample introducing part
The ideal conditions for the sample introduction phase vary based on the specific column type and equipment utilized It is essential to optimize these conditions by consulting the operation manual for each piece of equipment For instance, packed columns have particular setting conditions that should be carefully considered.
1) In the case of using a gas sampling syringe The packed column injection method shall be employed The temperature at the sample introducing part shall be set to about 150°C
2) In the case of using a gas sample introducing apparatus The tempera- ture of the gas sample introducing apparatus shall be set to about 150 °C b) Capillary column
When using a gas sampling syringe, either the split injection method or direct injection method should be utilized, with the sample introduction section maintained at a temperature of approximately 150°C.
When utilizing a gas sample introduction apparatus, either the split injection method or the direct injection method should be applied It is essential to maintain the temperature of both the sample introduction section and the apparatus at approximately 150°C for optimal performance.
8.5.2 Example of operation conditions for column
The conditions for column shall be a column temperature and a carrier gas flow rate at which the column would fully exhibit the separation performance as described in
8.3.2 a) or 8.3.2 b) Table 3 shows examples of conditions for column
Table 3 Examples of conditions for column a), b)
Separation Case of Packings Col umn dimensions Temperature of Carrier gas column condition col umn and the flow rate rise and fall of temperature
Packed Case 1 1,2,3-tris (2- Inside diameter: 3 mm, 60°C to 80 °C 10 mllmin to column cyanoethoxy) Length: 3 m to 5 m 50 mllmin propane (25 %) c)
Case 2 Polymer beads Inside diameter: 3 mm, 80°C to 100°C 40 mllmin to
Capillary Case 3 Stationary liquid: Inside diameter: 0.25 mm 50°C (5 min) 3 ml/min column 100 % methyl to 0.53 mm, -720 °C/min -7 silicone Length: 60 m to 105 m, 250°C (0 min)
Film thickness: 1 !-lm to 5!-lm
Case 4 Porous polymer: Inside diameter: 0.52 mm, 80°C (5 min) 3 mllmin silica gel Length: 30 m to 60 m -720 °C/min -7
For optimal separation performance in both packed and capillary columns, it is essential to use a column that meets or exceeds the specified standards The column's temperature and the flow rate of the carrier gas must align with the conditions necessary for effective separation of hydrogen sulfide from interfering substances In cases where separation is hindered by the presence of sulfur dioxide or polyphenylether, alternative strategies may be required.
To achieve optimal performance, the temperature and gas flow rates of each piece of equipment must be carefully set according to specific conditions outlined in the operation manual These optimal conditions vary by the type of detector used For instance, a thermal conductivity detector typically operates at a detector temperature of 250°C with an addition gas flow rate of 45 mL/min In contrast, a flame photometric detector requires a temperature of 200°C, with helium and combustion gas flow rates of 50 mL/min each, and a supporting air flow rate of 60 mL/min Meanwhile, an atomic emission detector operates at a higher temperature of 300°C, utilizing a purge gas flow rate of 0.5 L/min, along with a plasma gas flow rate of 35 mL/min, and supporting gas flow rates of 20 mL/min each for hydrogen and oxygen, with a sulfur monitor wavelength set at 181 nm.
Determination procedure ãããããããããããããããããããããããããããããããã19
The determination procedure involves maintaining the gas chromatograph's analytical conditions consistent with those used for preparing the working curve A specified amount of sample gas, obtained during the sampling procedure, is injected into the gas chromatograph to generate a gas chromatogram Subsequently, the peak height or area of hydrogen sulfide in the sample gas is measured, allowing for the quantification of hydrogen sulfide (in ng) based on the previously prepared working curve.
When measuring hydrogen sulfide content with a fluorescence photometric detector, the detector's response is roughly proportional to the square of the absolute amount injected The slope of the working curve varies based on factors such as the condition of the column and the combustion state of the detector Therefore, it is essential to establish a multi-point working curve for accurate measurements.
Preparation of working curveããã
To prepare the working curve, first, configure the apparatus based on the analytical and operational conditions of the gas chromatograph Next, create gas samples at the appropriate concentration using a gas sampling bag, gas collecting bottle, or a gas collecting can, as specified in section 6.3.1.4 b).
Using a gas sampling syringe 7), inject different amounts of sample gas into the gas chromatograph, and record the resultant gas chromatogram
As an alternative to conventional market-standard gases, gases produced using the permeation tube method can be utilized For detailed procedures on preparing standard gas via the permeation tube method, refer to JIS K.
For gas sample introduction, a gas sampling syringe can be substituted with a gas sample introducing apparatus When analyzing lower concentrations of gas, it is crucial to be cautious as adsorption may occur on the inner surfaces of the apparatus To establish a working curve, measure the peak height or peak area of hydrogen sulfide in the gas, and create a correlation between the mass (ng) of hydrogen sulfide and the corresponding peak height or peak area.
Calculation of hydrogen sulfide concentration ãããããããããããããããããããããããããããããããããããããããããããããããããã19
Calculate the concentration of hydrogen sulfide in the sample gas according to the following formulae and round off to two significant figures according to JIS Z 8401
V where, Cv : volume concentration of hydrogen sulfide in flue gas
Cm : mass concentration of hydrogen sulfide in sample gas (mg/m 3 )
A: mass of hydrogen sulfide in sample gas for analy- sis obtained by working curve (ng)
V: sample gas injection amount (ml)
0.657: volume of hydrogen sulfide corresponding to 1 mg of hydrogen sulfide (ml) 1.521: mass concentration of 1 vol ppm of hydrogen sulfide
10- 6 : factor to convert the unit of mass from ng to mg
10 6 : factor to convert ml/ml to vol ppm
Reagents and preparation of reagent solutions ãããããããããããããããããããããããããããããããããããããããããããããããã20
The following reagents shall be used a) N,N-Dimethyl-para-phenylenediammonium dichloride, specified in JIS K
The following chemicals are specified in various JIS standards: Iron (III) chloride hexahydrate (JIS K 8142), sulfuric acid (JIS K 8951), potassium iodide (JIS K 8913), iodine (JIS K 8920), hydrochloric acid (JIS K 8180), sodium thiosulfate pentahydrate (JIS K 8637), sodium carbonate (JIS K 8625), potassium iodate (JIS K 8005), soluble starch (JIS K 8659), and sodium sulfide nonahydrate (JIS K 8949).
The preparation of reagent solutions shall be as follows
9.1.2.1 Absorbing solution, prepared in accordance with 6.3.2.3 a)
9.1.2.2 N,N-Dimethyl-para-phenylenediammonium solution Dissolve 0.2 g of N,N-dimethyl-para-phenylenediammonium dichloride in 100 ml of sulfuric acid (1+3)
9.1.2.3 Iron (III) chloride solution Dissolve 1 g of iron (III) chloride hexahydrate in 100 ml of sulfuric acid (1+99)
9.1.2.4 Iodine solution (0.05 mol/L) 8) Dissolve 40 g of potassium iodide in about
To prepare the solution, dissolve 13 g of iodine in 25 ml of water, then dilute to a total volume of 1 L with additional water Next, add three drops of hydrochloric acid, mix thoroughly, and transfer the mixture into an opaque, airtight bottle Finally, store the bottle in a dark location to preserve the solution's integrity.
Note 8) The solution available on the market may also be used
To prepare a 0.1 mol/L sodium thiosulfate solution, weigh 13 g of sodium thiosulfate pentahydrate and 0.1 g of sodium carbonate, then dissolve them in 500 ml of oxygen-free water Store the solution in an airtight container and allow it to stand for 2 days before standardizing with potassium iodate, following the specified standardization procedure.
To standardize potassium iodate, heat approximately 0.36 g at 130°C for 2 hours, then cool in a desiccator Dissolve the cooled iodate in water and transfer it to a 250 ml volumetric flask, filling to the mark with water Accurately measure 25 ml of this solution into a 300 ml Erlenmeyer flask, add water to reach 100 ml, then incorporate 2 g of potassium iodide and 5 ml of diluted sulfuric acid (1:5) Stopper the flask, shake gently, and store it in a dark place.
To determine the iodine concentration, titrate the isolated iodine with a 0.1 mol/L sodium thiosulfate solution Once the yellow color of the solution fades, add approximately 1 mL of starch solution as an indicator and continue the titration until the blue color disappears, noting the volume used Additionally, perform a blank test under identical conditions to measure the volume consumed Finally, calculate the factor of the 0.1 mol/L sodium thiosulfate solution using the appropriate formula.
250 Cal +ao)xO.003567 100 where, f: factor of 0.1 mollL sodium thiosulfate solution m: sampling amount of potassium iodate (g)
B: purity of potassium iodate (mass ratio %)
`,`,,,,`,``,````,``````,,,`,-`-`,,`,,`,`,,` - al: amount of 0.1 mollL sodium thiosulfate solution consumed in titration in d) (ml) ao: amount of 0.1 mollL sodium thiosulfate solution consumed in blank test in e) (ml)
0.003 567: amount of potassium iodate corresponding to 1 ml of 0.1 mollL sodium thiosulfate solution (g)
To prepare a 10 g/L starch solution, dissolve 1 g of soluble starch in approximately 10 ml of water, then gradually add this mixture to 90 ml of hot water while stirring continuously Boil the solution for about one minute and allow it to cool It is essential to prepare this solution fresh, just before use.
To prepare a sulfide ion standard solution (S2- at 1 mg/ml), weigh approximately 3.8 g of sodium sulfide nonahydrate and wash it with a small amount of water Filter the solution to remove moisture and dissolve it in oxygen-free water to make a final volume of 500 ml For concentration determination, accurately measure 20 ml of a 0.05 mol/L iodine solution into a 300 ml Erlenmeyer flask with a ground stopper, then add 1 ml of hydrochloric acid Next, accurately measure 20 ml of the sulfide ion standard solution and add it to the iodine solution, ensuring the pipette tip is dipped into the solution Immediately stopper the flask tightly, shake to mix, and allow it to stand for 10 minutes.
To determine the concentration of sulfide ions, prepare a standard solution of sulfide ion (S2- at 1 mg/ml) and add it to an acidic iodine solution containing hydrochloric acid Titrate this mixture with a 0.1 mol/L sodium thiosulfate solution, and once the yellow color begins to fade, introduce 1 ml of a 10 g/L starch solution as an indicator Continue titrating until the blue color of the starch-iodine complex disappears In a separate step, accurately measure 20 ml of a 0.05 mol/L iodine solution into a 300 ml Erlenmeyer flask, add 1 ml of hydrochloric acid, and titrate with the same sodium thiosulfate solution Finally, calculate the concentration of the sulfide ion standard solution (C s in mg/ml) using the appropriate formula.
The concentration of the sulfide ion standard solution (Cs) can be calculated using the formula Cs = (b - a) x Jxl / 20 x 1.603 In this equation, 'a' represents the volume of 0.1 mol/L sodium thiosulfate solution consumed during titration (in ml), while 'b' indicates the volume of 0.1 mol/L sodium thiosulfate solution that corresponds to 20 ml of iodine solution (0.05 mol/L, in ml) The factor 'f' refers to the 0.1 mol/L sodium thiosulfate solution, and 1.603 denotes the mass of sulfide ion present in 1 ml of 0.1 mol/L sodium thiosulfate solution (in mg).
To prepare a sulfide ion standard solution (S2- at 10 µg/ml), accurately measure 1 ml of the sulfide ion standard solution (82-1 mg/ml) into a 100 ml volumetric flask Then, add oxygen-free water until the flask reaches the mark The concentration of the resulting solution should be determined based on the sulfide ion standard solution specified in section 9.1.2.7.
Apparatus and instrument ããããããããããããããããããããããããããããã23
The following apparatus and instrument shall be used
Photometer A spectrophotometer or a photoelectric photometer shall be used.
Determination procedure ãããããããããããããããããããããããããããããããã23
To determine the sample, first, take 20 ml of the prepared sample solution and place it in a 25 ml volumetric flask Next, add 2 ml of N,N-dimethyl-para-phenylenediammonium solution, stopper the flask, and gently mix Immediately afterward, add 1 ml of iron (III) chloride solution, stopper the flask again, and mix gently Finally, add water that is free from dissolved oxygen.
NOTE 3 to clause 4 of JIS K 0557) up to the mark
To prepare the analytical sample, do not shake the solution; instead, allow it to stand at room temperature for 30 minutes Next, transfer a portion of the solution into the absorption cell of a spectrophotometer or photoelectric photometer and measure the absorbance at approximately 670 nm For the contrast solution, take 20 ml of the absorbing solution in a 25 ml volumetric flask and follow the same standing procedure Finally, determine the mass of sulfide ion in milligrams using the working curve created for this analysis.
Preparation of working curve ãããããããããããããããããããããããã23
The preparation of working curve shall be as follows a) Take stepwise amounts from 0.5 ml to 2.0 ml of sulfide ion standard solution (8 2 -
To prepare a solution, measure 10 !lg/ml in 25 ml volumetric flasks and add 20 ml of the absorbing solution Follow the procedures outlined in sections 9.3 b) to 9.3 d) Finally, establish a correlation curve that relates the amount of sulfide ion (in mg) to the absorbance.
Calculation of hydrogen sulfide concentration
Calculate the concentration of hydrogen sulfide in the sample gas according to the following formulae and round it off to two significant figures according to JIS Z 8401
Vs where, Cv : volume concentration of hydrogen sulfide in sample gas (vol ppm)
Cm : mass concentration of hydrogen sulfide in sample gas (mg/m 3 ) a: mass of sulfide ion obtained in 9.3 e) (mg)
20: aliquot amount 20 of sample solution for analysis (ml)
Vs: sampling amount of sample gas under the standard condition calculated in 6.3.2.5 (L)
0.698: volume of hydrogen sulfide corresponding to 1 mg of sulfide ion (8 2 -) (ml)
1.063: mass of hydrogen sulfide corresponding to 1 mg of sulfide ion (8 2 -) (mg)
1.521: mass concentration of 1 vol ppm of hydrogen sulfide
Reagents and preparation of reagent solutions ãããããããããããããããããããããããããããããããããããããããããããããããã24
The following reagents shall be used a) Sodium thiosulfate pentahydrate, specified in JIS K 8637 b) Sodium sulfide nonahydrate, specified in JIS K 8949 c) Glycerin, specified in JIS K 8295 d) Sodium hydroxide, specified in JIS K 8576
The preparation of reagent solutions shall be as follows
10.1.2.1 Absorbing solution, prepared in accordance with 6.3.2.3 b)
10.1.2.2 0.1 mol/L Sodium thiosulfate solution, prepared in accordance with
10.1.2.3 Starch solution, prepared in accordance with 9.1.2.6 Prepare this solu- tion immediately before use
10.1.2.4 Sulfide ion standard solution (S2- 1 000 mg/L) Dissolve 3.8 g of sodium sulfide nonahydrate, 100 ml of glycerin and 2 g of sodium hydroxide in water to make
500 ml 8tore this solution in an airtight container and standardize it immediately before use The concentration of this solution shall be determined according to 9.1.2.7 a) to d)
To prepare a sulfide ion solution for the working curve at a concentration of 10 mg/L (S2-), dilute the sulfide ion standard solution (ranging from 82 to 1,000 mg/L) by a factor of 100 using the absorbing solution The concentration of the resulting solution should be determined based on the sulfide ion standard solution detailed in section 10.1.2.4.
To prepare a sulfide ion solution for the working curve at a concentration of 1 mg/L (S2-), dilute the sulfide ion standard solution (8 2 - 1,000 mg/L) by a factor of 1,000 using the absorbing solution The concentration of the resulting solution should be determined based on the sulfide ion standard solution outlined in section 10.1.2.4.
To prepare a working curve for sulfide ion solutions at a concentration of 0.1 mg/L, dilute the sulfide ion standard solution (8 2 - 10 mg/L) by a factor of 100 using an absorbing solution The concentration of the resulting solution should be determined based on the sulfide ion standard solution concentration outlined in section 10.1.2.4, which is 8 2 - 1,000 mg/L.
To prepare a sulfide ion solution for the working curve at a concentration of 0.01 mg/L, dilute the sulfide ion standard solution (8 2 - 10 mg/L) by a factor of 1,000 using the absorbing solution This dilution will allow for accurate measurement, with the concentration derived from the sulfide ion standard solution specified in section 10.1.2.4, which is 8 2 - 1,000 mg/L.
Apparatus and instruments ããããããããããããããããããããããããããã25
The following apparatus and instruments shall be used
10.2.1 Potentiometer, of high input resistance capable of reading response poten- tial of 0.1 mV or under (e.g digital type pH-mV meter, pH-mV meter with expanded span, ion meter, etc.)
10.2.2 Sulfide ion selective electrode, the solid state membrane type sulfide ion selective electrode in which silver sulfide is to be the main component
10.2.3 Reference electrode, of the silver-silver chloride internal electrode type 10.2.4 Magnetic stirrer, coated with fluoroethylene resin, provided with a rotor.
Determination procedure ãããããããããããããããããããããããããããããããã25
To determine sulfide ion concentration, connect a sulfide ion selective electrode and a reference electrode to a potentiometer Begin by rinsing the electrodes with water and drying them Next, transfer the prepared sample solution to a 50 ml dry beaker and immerse both electrodes for analysis.
`,`,,,,`,``,````,``````,,,`,-`-`,,`,,`,`,,` - and measure the response potential (Eo) while agitating with a magnetic stirrer at a definite rate
To analyze the sulfide ion concentration in a sample solution, transfer a portion of 200 ml to a beaker, or use the entire 20 ml sample if applicable, avoiding any washing with water Determine the approximate sulfide ion concentration using the working curve established in section 10.4, preparing a sulfide ion working curve solution that is 100 to 1,000 times the concentration obtained in sections 10.1.2.4 to 10.1.2.8 Add 0.2 ml of this working curve solution to the sample solution and measure the response potential (E1) Subsequently, introduce another 0.2 ml of a different concentration from the working curve to the solution measured in the previous step, recording the new response potential (E2) Repeat this process to measure a third response potential (E3).
To prepare the working curve for sulfide ions, transfer an appropriate volume of the solution (ranging from 0.01 to 8 mg/L) into a 50 ml beaker Follow the procedure outlined in section 10.3 and measure the response potential using a potentiometer.
To accurately determine sulfide ion concentration using an ion meter as a potentiometer, first correct the meter with two different sulfide ion solutions to establish a working curve Then, repeat the procedure with solutions of varying concentrations (0.1 mg/L, 1 mg/L, and 10 mg/L) to measure the corresponding response potentials Finally, plot the logarithm of sulfide ion concentrations against the response potentials to create a relationship curve that illustrates the correlation between sulfide ion concentration (mg/L) and response potential.
Calculation of hydrogen sulfide concentration
To determine the concentration of sulfide ions in a sample solution for analysis, use the specified formula and round the result to two significant figures in accordance with JIS Z 8401 standards.
A: mean value of measured values of sulfide ion con- centration in sample solution for analysis (mg/L)
A 1, A 2 , A3: sulfide ion concentration in sample solution for analysis obtained by adding 0.2 ml, 0.4 ml, 0.6 ml of the solution for sulfide ion working curve to the sample solution for analysis (mg/L)
C: concentration of the solution for sulfide ion work- ing curve prepared in 10.3 d) (mg/L) i1El, i1E2, i1E3: difference between the response potential Eo ob- tained in 10.3 c) and response potentials E1, E 2 ,
To calculate the hydrogen sulfide concentration in flue gas, utilize the formula derived from the working curve established in section 10.4 This involves assessing the potential slope near the sample solution concentration and determining the response potential associated with a tenfold change in concentration (V).
Vs y where, Cv : volume concentration of hydrogen sulfide in sample gas
Cm : mass concentration of hydrogen sulfide in sample gas
A: mean value of the concentration of sulfide ion in the sample solution for analysis obtained in a) (mg/L)
V: amount of sample solution for analysis prepared in 7.2 (ml) v~: sampling amount of sample gas under the standard condition calculated in 6.3.2.5 (L)
0.698: volume of hydrogen sulfide corresponding to 1 mg of sulfide ion (8 2 -) (ml)
1.063: mass of hydrogen sulfide corresponding to 1 mg of sul- fide ion (8 2 -) (mg)
1.521: mass concentration of 1 vol ppm of hydrogen sulfide
The analysis results must include essential information such as the name of the individual who conducted the gas sampling, along with the date and time of the sampling Additionally, it should detail the sampling method and the preparation of the analysis sample, specify the determination method used, and provide the name of the person who performed the analysis, including the corresponding date and time Finally, the analysis values and any other relevant notes should also be documented.
Annex A (informative) Silver nitrate potentiometric titration
A.l Summary of silver nitrate potentiometric titration
The summary of silver nitrate potentiometric titration is shown in table A.I
Table A.l Silver nitrate potentiometric titration
Determination method Sampling Determination NOTE range
Flue gas absorption is conducted using an absorbing bottle, with concentrations starting from 10 vol ppm up to 500 vol ppm The process involves potentiometric titration of the absorbing solution, which contains concentrations of 100 vol ppm or higher, utilizing silver nitrate methanol as outlined in section A.2.2.1 to accurately determine hydrogen levels.
Sampling amount titration curve sulfide of sample gas: 20 L 100 vol ppm or under:
Gran plotting method shall be applied
A.2 Reagents and preparation of reagent solutions
The reagents and preparation of reagent solutions are as follows
The reagents utilized in this study include potassium hydroxide (JIS K 8574), methanol (JIS K 8891), ammonia solution (JIS K 8085), sodium chloride (JIS K 8005), silver nitrate (JIS K 8550), and potassium nitrate (JIS K 8548).
A.2.2 Perparation of reagent solutions The preparation of reagent solutions is as follows
A.2.2.1 Absorbing solution Dissolve 60 g of potassium hydroxide in 50 ml of water, and add methanol to the mark to make 1 L
A.2.2.2 Ammonia solution (1+14) It is prepared by adding 1 volume of ammonia solution and 14 volume of water
To prepare a 0.01 mol/L silver nitrate solution in methanol, dissolve 0.17 g of silver nitrate in 100 ml of methanol, then add methanol to reach the final volume The concentration of this solution will be determined through standardization.
To standardize sodium chloride, heat it at 600°C for one hour, then cool it in a desiccator Accurately weigh approximately 0.58 g of the salt, dissolve it in 20 ml of water, and transfer the solution to a 100 ml volumetric flask, filling it to the mark with water Next, take 10 ml of this solution in a 250 ml beaker and add 40 ml of methanol Immerse an ion-selective electrode and a reference electrode into the beaker and perform a potentiometric titration using a 0.01 mol/L silver nitrate methanol solution Plot the volume of silver nitrate solution added (ml) on the x-axis and the response potential difference (V) on the y-axis to create a titration curve From this curve, determine the volume of 0.01 mol/L silver nitrate solution consumed during the titration and calculate the corresponding factor.
(j) of 0.01 moliL silver nitrate methanol solution according to the following formula f=~ a where, f: factor a: amount of silver nitrate methanol solution con- sumed in titration (ml) b: 0.01 moliL sodium chloride solution (ml)
Notes 1) A salt bridge of potassium nitrate or a double liquid junction type reference electrode is used, in order to prevent potassium chloride solution from mixing in the titration solution
2) As an alternative to the potentiometric titration, the silver nitrate titration method using an adsorption indicator (for example, fluores- cein sodium, etc.) may be applied
The following apparatus and instruments are used
A.3.1 Sample gas sampling apparatus and absorbing bottle, as shown in fig- ure 3 and figure 4, respectively
A.3.3 Silver ion selective electrode, of solid state membrane type, of which the main component is silver sulfide
The double liquid junction reference electrode features a silver-silver chloride internal electrode and utilizes a potassium nitrate solution free of chloride ions for the internal liquid within the outer tube.
A.3.5 Magnetic stirrer, as shown in 10.2.4
A.4 Sampling of sample gas and preparation of sample solution for analysis
To prepare the sample solution for analysis, begin by adding 50 ml of the absorbing solution specified in section A.2.2.1 to each of the two absorbing bottles illustrated in figure 3 Prior to introducing the sample gas, ensure that the air in the conduit tube is completely replaced with the sample gas using a bypass or similar method The volume of the sample gas and the suction rate must adhere to the specifications outlined in table A.2.
Table A.2 Sampling amount of sample gas and suction rate
Concentration of hydrogen sulfide vol ppm Sampling amount L Suction rate L/min
To ensure accurate analysis, simultaneously measure the temperature and pressure while sampling the gas Once the gas sampling is complete, transfer the solution from the absorbing bottle into a 200 ml volumetric flask using the absorbing solution, and fill to the mark with the absorbing solution to prepare the sample for analysis.
Note 3) Perform all of the procedures avoiding direct sunshine
The procedure of titration is as follows a) Take a portion of the sample solution of an amount calculated to be suitable in a
To analyze the sample gas concentration using a hydrogen sulfide detector, prepare a 250 ml beaker by diluting a 0.05 mol/L ammonia solution (1+14) and adding 2.5 ml of this solution to the beaker, then fill with water to reach 50 ml Immerse the silver ion selective and reference electrodes in the solution, connecting them to a potentiometer After allowing the response potential to stabilize, titrate with a 0.01 mol/L silver nitrate methanol solution from a burette, recording the response potential until surpassing the titration endpoint Measure the volume of silver nitrate solution consumed at the endpoint For the blank test, replicate the sample preparation in a separate 250 ml beaker and follow the same titration procedure to determine the blank test value based on the volume of silver nitrate solution used.
The drawing is performed as follows, depending on the concentration of hydrogen sulfide
In addition, when a potentiometer with built-in function of A.6.l or A.6.2 is used, the function may be utilized
To analyze samples with a concentration of 100 ppm or higher using the titration curve method, begin by plotting the added amounts of 0.01 mol/L silver nitrate methanol solution on the x-axis against the response potential (E) on the y-axis for both the sample and blank test solutions This will create a titration curve Next, determine the titration curve by connecting the plotted points, and identify the amounts of silver nitrate solution consumed during the titration for both the sample (a) and the blank (b).
A.6.2 In the case of under 100 ppm (Gran plotting method)
An example of drawing according to Gran plotting method is given in figure A.I
Added amount of 0.01 mol/L silver nitrate methanol solution ax (ml)
Figure A.l Example of Gran plotting method
The procedures of creating Gran plot are as follows a) Calculate 4) the added amount of 0.01 mollL silver nitrate methanol solution (ax) and the corresponding response potential difference (V 2 + ax) 10e/s (E)
In the titration process, V2 represents the aliquot amount of the sample solution, while S indicates the potential inclination of the silver ion selective electrode The difference between the response potentials, E1 (for a 0.01 mol/L silver nitrate methanol solution) and E2 (for the same solution diluted tenfold), typically ranges from 57 mV to 59 mV at 25°C To analyze the data, plot ax (in mL) on the x-axis and (V2 + ax) × 10e/s on the y-axis on graph paper, and then draw a straight line connecting each plotted point.
To determine the endpoint of titration, identify the intersection point of the extended straight line with the abscissa Measure the volume (a) of the 0.01 mol/L silver nitrate methanol solution used during the titration, noting that a blank test is unnecessary in this scenario.
A.7 Calculation of concentration of hydrogen sulfide
Calculate the volume concentration of hydrogen sulfide in the sample gas by the following formulae, and round the result to two significant figures according to JIS Z
Vs x r where, C v : volume concentration of hydrogen sulfide in sample gas (vol ppm)
C m : mass concentration of hydrogen sulfide in sample gas (mg/m 3 )
0.112: volume of hydrogen sulfide corresponding to 1 ml of 0.01 mollL silver nitrate methanol solution (ml)
1.521: mass concentration of 1 vol ppm of hydrogen sulfide
(mg/m 3 ), 34.086/22.41 a: amount of 0.01 mol/L silver nitrate methanol solu- tion obtained in A.5 a) to e) (ml) b: blank test value obtained in A.5 f) (ml)
The sampling amount of gas under standard conditions, as specified in section 6.3.2.5, is represented by Vs (L) The aliquot ratio, denoted as r, is the ratio of the volume of the aliquot taken (in ml) to the volume of the sample solution used for analysis (in ml) Additionally, f represents a factor of 0.01 mol/L for silver nitrate methanol solution.
Sulfur dioxide conversion ultraviolet ray fluorescent method
The summary of the sulfur dioxide conversion ultraviolet ray fluorescent method is as shown in table B.1
Table B.I Sulfur dioxide conversion ultraviolet ray fluorescent method