GB/T 15959-1995 Water quality - Determination of adsorbable organic halogen (AOX) - Microcoulometric method
Some standard content:
National Standard of the People's Republic of China
Water quality--Determination of adyorbahleorgamichalogens(Aox)-MicrocoulometricmethodGB/T 15959—1995
This standard is equivalent to the international standard IS09562:1989. Water quality-Determination of adsorbable organic halogens (AOX)". 1 Subject content and scope of application
1.1 This standard specifies the microcoulometric method for determining organic halides (AOX) adsorbable on activated carbon in water. It is necessary to blow off before adsorption. Volatile organic halides can be directly determined. 1.2 This standard is applicable to the determination of organic halides (AOX) in drinking water, groundwater, surface water and sewage. The determination range is 10~400/L. If the upper limit is exceeded, the sampling amount can be reduced. 1.3 If the dissolved organic carbon in the water sample is >10 mg/L and the inorganic oxide content is >1 g/L, it must be diluted before analysis. 1.4 When there are suspended solids in the water sample, the organic halogen compounds it contains are also included in the measured value. 1.5 In order to avoid the colloid interference that may be formed when separating the activated carbon from the aqueous phase, it is necessary to add filter aids such as diatomaceous earth to make the carbon coagulate and overcome the difficulty of filtration.
1.6 When the water sample contains active chlorine, the A0X value will be high, so sodium sulfate should be added immediately after sampling. When there are undissolved inorganic chlorides, biological cells (such as microorganisms, algae), etc. in the water sample, the sample needs to be acidified first and then analyzed after 8 hours. 1.7 Inorganic iodide can interfere with adsorption and detection, organic iodide will lead to non-reproducible high results, and high concentrations of inorganic membrane compounds will also interfere.
2 Definitions
The following definitions apply to this standard:
2.1 Adsorbable organic halogen (A): refers to the total amount of oxygen and bromine in the halogen combined with organic compounds measured by the method specified in the standard, measured in terms of rate.
2.2 Soluble organic carbon (IX) C): The content of organic carbon in the water sample after filtering through a 0.1.45um membrane 3 Principle
The water sample is acidified with nitric acid (the water sample needs to be stripped if necessary, and the volatile organic halides are directly determined by combustion and pyrolysis). The organic compounds in the water sample are adsorbed with activated carbon, and then washed with sodium nitrate solution to separate the inorganic halides. The carbon adsorbed with organic matter is burned and pyrolyzed in an oxygen stream, and finally the mass concentration of hydrogen sulfide is determined by the microcoulometric method. 4 Reagents
Unless otherwise specified, analytical reagents that meet national standards are used during analysis. The amount of AOX in the water, chemicals and gases used must be tested, and the obtained AOX value does not affect the lower limit of determination of the sample. Qualified water should be stored in a glass bottle with a ground mouth. 4.1 Activated carbon:
National Environmental Protection Agency approved on December 21, 1995, implemented on August 1, 1996
Iodine value: 210501
Chloride: ≤0.0015%
GB/T 15959—1995
Particle size: about 50μm, for oscillation adsorption: Particle size: about 100um, for column adsorption 4.2 Nitric acid (HNO,): p=1. 42 g/ml. 4.3 Hydrochloric acid: c(HCI)=0.100 mol/L.a4. 4 Sulfuric acid (H,SO,): p=1. 84 g/ml. 4.5 Glacial acetic acid (CH,COOH), high-grade purity. 4.6 Sodium chloride (NaCI); standard reagent.
4.7 Oxygen (O,).
4.8 Nitrogen (N.).
4.9 Sodium nitrate stock solution: 17g/L
Weigh 17g of sodium nitrate (NaNO) and dissolve it in water, add 1.4ml nitric acid (4.2), transfer it to a 1000ml volumetric flask, and dilute it to the mark with water.
4.10 Sodium nitrate washing solution: 0.85g/L
Take 50ml of sodium nitrate stock solution (4.9), transfer it to a 1000ml volumetric flask, and dilute it to the mark with water. 4. 11 Sodium sulfite solution: (NaSO,) = 0.2mel/L. 4.12 Chloride standard stock solution, 1000 pgCl/ml. Weigh 48g of 0.1% sodium chloride (4.6) that has been dried to constant weight at 110°C and dissolve in water, transfer to a 100ml volumetric flask, and dilute to scale with water.
4.13 Chloride standard working solution: 100gCl/ml. Pipette 10.0ml of chloride standard stock solution (4.12) into a 100ml volumetric flask and dilute to scale with water. 4.14 Acetic acid electrolyte: (7+3). Measure 70ml of glacial acetic acid (4.5) and add 30ml of water, mix. 4.15 Parachlorophenol purchased solution, 200μgCl/ml. Weigh 72.5.m parachlorophenol (CH;CIO) and dissolve in water, transfer to a 100ml volumetric flask, and dilute to scale with water. 5 Instruments
Commonly used experimental instruments and:
5.1 Absorbable organic halogen tester and blow-off device 5.1.1 Combustion pyrolysis
A pyrolysis furnace consisting of a 3hcm long and 2~3cm diameter quartz furnace and a tubular furnace, with adjustable heating temperature, which can reach at least 950℃, as shown in the figure below.
5.1.2 Non-standard quartz boat
# Product import
Quartz boat
GB/T15959—1995
Temperature control
The size of the quartz boat matches the inner diameter of the quartz tube (5.1.1). 5.1.3 Microcoulometer
Amplifier
Tidal analyzer
A microcoulometer capable of measuring 1rgCl with a relative standard deviation of <10%. 5.1.4 Dryer
Electrolysis slow
Measurement plate
Clearing tank
Sea mixer
Inject appropriate amount of sulfuric acid (4.4) into the dryer to dry the pyrolysis reaction gas, and ensure that the sulfuric acid in the dryer cannot flow back. 5.1.5 Gas inlet
When blowing off, the inlet is connected to the inlet of the gas washing bottle with a silicone rubber seal. 5.2 Column adsorption device
5.2.1 Adsorption device
The adsorption column is 40~50mm long, 2~3mm in inner diameter, and contains 40~50mg of activated carbon (41). A small amount of glass is inserted into the end of the column. Use two adsorption columns of the same specifications to connect, and then connect with a sample tube of 10ml volume, and use the pressure of nitrogen to adjust the filtration flow rate. 5.3 Shake the adsorption device
5. 3. 1 Filter
A filter funnel, capacity 0.15L, filter plate diameter 25mm. 5.3.2 Filter membrane
The chloride content of the filter membrane is low, the membrane diameter is 25mm, and the pore size is 0.45μm. 5.3.3 Electric oscillator
The carrier plate is attached with a fixed conical flask, the oscillation box is turned 150-250 times/min, the amplitude is G~10cm, 6 samples
Sampling, transportation and storage use glassware III. 6.1 If the sample contains oxidants (<1.6), immediately after sampling, add 5 ml of sodium sulfite (4.11) to every 100 ml of water. 6.2 Use nitric acid (4.2) to adjust the pH value of the water sample to between 1.5 and 2.0. If necessary, place it for 1 h, see 1.6. 6.3 The glass bottle is filled with water sample without leaving any bubbles. GB/T 15959—1995
6.4 After sampling, analyze as soon as possible. If it is necessary to acidify the water sample for storage, store it at 4°C - but not more than 3 days. 6.5 The water sample should be placed at room temperature during analysis.
7 Steps
7.1 Separation steps
7.1.1 Stripping and determination of volatile halides If the water sample contains less than 5% volatile halides, the stripping step can be omitted. Take 100 ml of water sample and pour it into the gas washing bottle. Connect the inlet end of the washing bottle to the oxygen supply pipe with a silicone hose, and connect the outlet end to the inlet of the combustion quartz tube. Insert the oxygen inlet end as deep as possible into the bottom of the water sample and adjust the oxygen flow rate to 150 ml/min to ensure that the bubbles are evenly distributed. When the temperature of the pyrolysis furnace reaches 950C, send the mixed gas into the combustion quartz.
Blow off for at least 10 minutes. When the microvolt signal display value no longer increases, the reaction is over. Determine the base content of the organic halogen that can be blown off by the microcoulometric method. 7.1.2 Adsorption steps
The adsorption method can be column adsorption or vibration bacteria adsorption. 7.1.2.1 Column adsorption
Take 100 ml of the pretreated (6) water sample, add 5 ml of sodium nitrate stock solution (4.9), and check the pH value 2. Then mix the water and pour it into (5.2,1) Put the lid on the sample tube, adjust the nitrogen pressure, and filter the water sample at a flow rate of 3 ml/min. Then use 10-20 ml of sodium nitrate washing solution (1.10) at a flow rate of 3 ml/min, transfer the wet activated carbon to the quartz boat and measure according to the steps described in (7.2). Note: The A(IX) value obtained by the second adsorption column should not exceed 10% of the A(OX) value of the first adsorption column, otherwise the water sample will be diluted. 7.1.2.2 Oscillating adsorption Take 100 ml of the pretreated water sample, pour it into a 250 ml conical flask, add ml nitric acid to reserve carboxylic acid, check the pH value <2, and then add 40~50 mg active carbon (4.1). Place the conical flask on the oscillator support plate (5.3.3), oscillate and float for more than 1 hour, filter through the filter membrane (5.3.2), wash the filter cake several times with about 25 ml of sodium nitrate, transfer the wet filter cake and filter membrane together into a quartz boat, and measure according to the steps described in (7.2).
Note: (i) A constant TX value will indicate that the adsorption is complete, so the LXK test is used to check the degree of adsorption of activated carbon in the water sample. Take different volumes of water samples (for example 50 ㎡l and 100 The completeness of adsorption can be checked by adding 0.5 ml of lead sulfate (6,3 μg/ml) solution while stirring the activated carbon. Then adjust the pH value of the suspension to between 6.8 and 7.2 with sodium carbonate. Add 0.2-0.4 ml of lead sulfate (6,3 μg/ml) solution while stirring. The partially hydrolyzed amide aqueous solution (0.2r/L) is stirred for a short time, and the floccules are settled. The supernatant is decanted and the floccules are treated according to the steps described in (7.1.2.2). 7.2 Combustion
The temperature of the combustion pyrolysis furnace is at least 950℃. For other operating methods, please refer to the instruction manual provided by the instrument manufacturer. 7.2.1 Connect the oxygen supply to the combustion quartz tube and the sulfuric acid drying and titration cell in the prescribed order, and check that each interface is leak-proof, see figure.
Note: It is necessary to avoid the siphoning back of sulfuric acid into the combustion chamber when the temperature and pressure are reduced. 7.2.2 Adjust the oxygen flow rate to 150ml/min. 7.2.3 Slowly push the quartz boat into the combustion quartz Preheating section in the tube ensures that the activated carbon moisture gradually dissipates. Note: The volume, residence time, temperature and gas flow rate of the activated carbon can affect the measurement results. 7.3 Calibration and verification
The microcoulometer should be calibrated frequently every day.
7.3.1 Calibration of microcoulometer
GB/T15959—1995
The electrolyte (4.14) in the titration cell must be replaced by about 70ml, and after stirring to stabilize EF, calibrate with 10.0rl chloride standard solution (4.13), and then inject 1μl, 2μl, 3μ, 4μ, 5l, 6μl, 7μl, 8, 9l and 10=l of hydrochloric acid solution (4.3) into the titration cell in turn to determine the amount of charge migration in each case. According to formula (1), a linear regression curve is drawn for the series of measurements. Q=aXQ +b
Where: Q: measured charge transfer amount, C: Q known charge transfer factor, C:
slope of the regression curve (electrolysis current efficiency); 3
force - intercept of the regression curve on the ordinate. The known charge amount can be obtained from formula (2).
Where: Vm - volume of hydrochloric acid solution, I.:co - actual concentration of hydrochloric acid solution, nol/L., F -: Faraday constant, F-96487C/mol.t13
7.3.2 Verification of the whole steps
Measure the A0x value of 10 pl, 20ul, 40μl, 60μl, 80ul of the standard solution (4.13) and follow the steps described in (5.2) or (5.3). Perform back analysis on the results of the measurement. The correlation coefficient is ≥0.999. To check the whole procedure, a standard solution with a medium concentration within the working range should be analyzed at each step. The difference between the measured value and the known value should not exceed 10%.
7.4 Blank determination
7.4.1 Blank of the whole procedure
The blank value of the whole procedure should not exceed 30gCI/1. If necessary, the adsorption step, the combustion step and the microcoulometric determination should be checked separately. Chemicals or other factors may cause the contamination of laboratory air with organic compounds. If the laboratory air is seriously polluted, even the dead volume of the stripping device can cause the result to be biased high. In order to prevent the determination result from being biased high, the activated carbon filter should not be sucked under any circumstances
If flocculants and filter aids are added, the blank of these materials will be determined. 7.4.2 Determine the blank according to (7.1.2.1)
Replace the water sample with 100ml of experimental water and follow the steps described in (7.1.2.1). 7.4.3 Determine the narrow
according to (7.1.2.2) Take 50ml of sodium nitrate washing solution, add 40~~50mg of activated carbon (4.1), and shake for 1h. Filter and wash the activated carbon according to the steps described in (7.1.2.2), and determine the content of organic fluorine. 8. Expression of results
Calculation method: Calculate the mass concentration of adsorbable organic halogen (AOX) by formula (3). ci
武Cr
I N+ N- N)
-The mass concentration of AOX is expressed as μgC1/L.1
N. —-empty value (according to 7.4.2), C:
measured value of strippable organic halogen, C:
N,——measured value of non-strippable organic halogen, C, M-
molar mass of chloride, M—35.46×10°g/mol; -volume of strippable sample, L:
GB/T 15959-1995
V, used for the volume of non-strippable sample, L; α and F have the same meaning as in formulas (1) and (2): if the companion crystal is not stripped, N, V, can be omitted. Note: The value measured by the second adsorption column is used to verify the degree of complete adsorption and is not included in the result. 9 Precision and Accuracy
Precision and uncertainty are shown in the table below.
Precision
Experimental case
Water sample
Drinking water
Surface water
Drinking water
Measured value
Water sample
Repeatability
Concentration accuracy
Relative standard deviation
Reproducibility
Standard deviation
Relative standard deviation
Reproducibility
Standard deviation
Relative standard deviation
Accuracy
Collective yield, %
1》Organic oxide wastewater, if the wastewater contains more suspended solids, when it is mixed again, it needs to be separated by high-speed centrifugation, and the supernatant is diluted and measured. A1 Adsorption performance of activated carbon
9—1995
GB/T15959
Appendix A
Performance and use of activated carbon
(Supplement)
Purchased activated carbon with appropriate adsorption capacity and low inorganic chloride content, or chromatographically pure activated carbon can be used for the determination of AOX.
Usage of activated carbon
Activated carbon easily adsorbs compounds (including other organic halogen compounds in the air), and it loses its activity after being exposed to the air for 5 days. In order to reduce the blank value of carbon, take more than 1.5 to 2.0 qualified activated carbon and place it in a sealed glass bottle for standby use (\day usage). Once the activated carbon in the sealed bottle is opened, it must be used on the same day, and the remaining cannot be used again. Additional remarks:
This standard is proposed by the Science and Technology Standards Department of the State Environmental Protection Administration. This standard is drafted by the Liaoning Provincial Environmental Protection Science Research Institute. The main drafters of this standard are Ye Yangxin, Liu Tao, Gong Dongjie and Yue Kezhi. The National Environmental Protection Administration is responsible for interpreting this standard.After oscillation for more than 1 hour, filter through the filter membrane (5.3.2), wash the filter cake several times with about 25 ml of sodium nitrate, transfer the wet filter cake and filter membrane together into a quartz boat, and measure according to the steps described in (7.2).
Note: (i) A constant TX value will indicate that the adsorption is complete, so the LXK measurement can be used to check the completeness of the adsorption of activated carbon in the water sample. Taking different volumes of water samples (for example, 50 ㎡l and 100 ml) can be used to check the completeness of the adsorption. When the difference between the measured A(0X) values is 1% or more, the adsorption is complete. For water containing high molecular weight components (such as pulp filter water), the adsorption time needs to be more than 1 hour, so the shaking time should also be extended. It can be up to overnight.) If the filtration is smooth and the total floating matter can be avoided, add 0.5 ml of lead sulfate (6,3 μg) solution while stirring the activated carbon. Then adjust the pH value of the suspension to between 6.8 and 7.2 with sodium carbonate. Add 0.2 to 0.4 ml of partially hydrolyzed dilute amide aqueous solution (0.2 ml/L) while stirring. Continue stirring for a short time. The floccules will settle. The supernatant will be decanted and the floccules will be treated according to the steps described in (7.1.2.2). 7.2 Combustion
The temperature of the combustion pyrolysis furnace should reach at least 950°C. For other operating methods, please refer to the instruction manual provided by the instrument manufacturer. 7.2.1 Connect the oxygen supply to the combustion quartz tube and the sulfuric acid drying and titration cell in the specified order, and prevent air leakage from each interface, see Figure.
Note: It is necessary to avoid the possible siphoning back of sulfuric acid into the combustion chamber when the temperature and pressure are reduced. 7.2.2 Adjust the oxygen flow rate to 150 ml/min. 7.2.3 Slowly push the quartz boat into the preheating section of the combustion quartz tube to ensure that the activated carbon moisture gradually dissipates. Note: The volume, residence time, temperature and gas flow rate of the activated carbon can affect the measurement results. 7.3 Calibration and verification
The microcoulometer should be calibrated frequently every day.
7.3.1 Calibration of microcoulometer
GB/T15959—1995
The electrolyte (4.14) in the titration cell must be replaced by about 70ml, and after stirring to stabilize EF, calibrate with 10.0rl chloride standard solution (4.13), and then inject 1μl, 2μl, 3μ, 4μ, 5l, 6μl, 7μl, 8, 9l and 10=l of hydrochloric acid solution (4.3) into the titration cell in turn to determine the amount of charge migration in each case. According to formula (1), a linear regression curve is drawn for the series of measurements. Q=aXQ +b
Where: Q: measured charge transfer amount, C: Q known charge transfer factor, C:
slope of the regression curve (electrolysis current efficiency); 3
force - intercept of the regression curve on the ordinate. The known charge amount can be obtained from formula (2).
Where: Vm - volume of hydrochloric acid solution, I.:co - actual concentration of hydrochloric acid solution, nol/L., F -: Faraday constant, F-96487C/mol.t13
7.3.2 Verification of the whole steps
Measure the A0x value of 10 pl, 20ul, 40μl, 60μl, 80ul of the standard solution (4.13) and follow the steps described in (5.2) or (5.3). Perform back analysis on the results of the measurement. The correlation coefficient is ≥0.999. To check the whole procedure, a standard solution with a medium concentration within the working range should be analyzed at each step. The difference between the measured value and the known value should not exceed 10%.
7.4 Blank determination
7.4.1 Blank of the whole procedure
The blank value of the whole procedure should not exceed 30gCI/1. If necessary, the adsorption step, the combustion step and the microcoulometric determination should be checked separately. Chemicals or other factors may cause the contamination of laboratory air with organic compounds. If the laboratory air is seriously polluted, even the dead volume of the stripping device can cause the result to be biased high. In order to prevent the determination result from being biased high, the activated carbon filter should not be sucked under any circumstances
If flocculants and filter aids are added, the blank of these materials will be determined. 7.4.2 Determine the blank according to (7.1.2.1)
Replace the water sample with 100ml of experimental water and follow the steps described in (7.1.2.1). 7.4.3 Determine the narrow
according to (7.1.2.2) Take 50ml of sodium nitrate washing solution, add 40~~50mg of activated carbon (4.1), and shake for 1h. Filter and wash the activated carbon according to the steps described in (7.1.2.2), and determine the content of organic fluorine. 8. Expression of resultsWww.bzxZ.net
Calculation method: Calculate the mass concentration of adsorbable organic halogen (AOX) by formula (3). ci
武Cr
I N+ N- N)
-The mass concentration of AOX is expressed as μgC1/L.1
N. —-empty value (according to 7.4.2), C:
measured value of strippable organic halogen, C:
N,——measured value of non-strippable organic halogen, C, M-
molar mass of chloride, M—35.46×10°g/mol; -volume of strippable sample, L:
GB/T 15959-1995
V, used for the volume of non-strippable sample, L; α and F have the same meaning as in formulas (1) and (2): if the companion crystal is not stripped, N, V, can be omitted. Note: The value measured by the second adsorption column is used to verify the degree of complete adsorption and is not included in the result. 9 Precision and Accuracy
Precision and uncertainty are shown in the table below.
Precision
Experimental case
Water sample
Drinking water
Surface water
Drinking water
Measured value
Water sample
Repeatability
Concentration accuracy
Relative standard deviation
Reproducibility
Standard deviation
Relative standard deviation
Reproducibility
Standard deviation
Relative standard deviation
Accuracy
Collective yield, %
1》Organic oxide wastewater, if the wastewater contains more suspended solids, when it is mixed again, it needs to be separated by high-speed centrifugation, and the supernatant is diluted and measured. A1 Adsorption performance of activated carbon
9—1995
GB/T15959
Appendix A
Performance and use of activated carbon
(Supplement)
Purchased activated carbon with appropriate adsorption capacity and low inorganic chloride content, or chromatographically pure activated carbon can be used for the determination of AOX.
Usage of activated carbon
Activated carbon easily adsorbs compounds (including other organic halogen compounds in the air), and it loses its activity after being exposed to the air for 5 days. In order to reduce the blank value of carbon, take more than 1.5 to 2.0 qualified activated carbon and place it in a sealed glass bottle for standby use (\day usage). Once the activated carbon in the sealed bottle is opened, it must be used on the same day, and the remaining cannot be used again. Additional remarks:
This standard is proposed by the Science and Technology Standards Department of the State Environmental Protection Administration. This standard is drafted by the Liaoning Provincial Environmental Protection Science Research Institute. The main drafters of this standard are Ye Yangxin, Liu Tao, Gong Dongjie and Yue Kezhi. The National Environmental Protection Administration is responsible for interpreting this standard.After oscillation for more than 1 hour, filter through the filter membrane (5.3.2), wash the filter cake several times with about 25 ml of sodium nitrate, transfer the wet filter cake and filter membrane together into a quartz boat, and measure according to the steps described in (7.2).
Note: (i) A constant TX value will indicate that the adsorption is complete, so the LXK measurement can be used to check the completeness of the adsorption of activated carbon in the water sample. Taking different volumes of water samples (for example, 50 ㎡l and 100 ml) can be used to check the completeness of the adsorption. When the difference between the measured A(0X) values is 1% or more, the adsorption is complete. For water containing high molecular weight components (such as pulp filter water), the adsorption time needs to be more than 1 hour, so the shaking time should also be extended. It can be up to overnight.) If the filtration is smooth and the total floating matter can be avoided, add 0.5 ml of lead sulfate (6,3 μg) solution while stirring the activated carbon. Then adjust the pH value of the suspension to between 6.8 and 7.2 with sodium carbonate. Add 0.2 to 0.4 ml of partially hydrolyzed dilute amide aqueous solution (0.2 ml/L) while stirring. Continue stirring for a short time. The floccules will settle. The supernatant will be decanted and the floccules will be treated according to the steps described in (7.1.2.2). 7.2 Combustion
The temperature of the combustion pyrolysis furnace should reach at least 950°C. For other operating methods, please refer to the instruction manual provided by the instrument manufacturer. 7.2.1 Connect the oxygen supply to the combustion quartz tube and the sulfuric acid drying and titration cell in the specified order, and prevent air leakage from each interface, see Figure.
Note: It is necessary to avoid the possible siphoning back of sulfuric acid into the combustion chamber when the temperature and pressure are reduced. 7.2.2 Adjust the oxygen flow rate to 150 ml/min. 7.2.3 Slowly push the quartz boat into the preheating section of the combustion quartz tube to ensure that the activated carbon moisture gradually dissipates. Note: The volume, residence time, temperature and gas flow rate of the activated carbon can affect the measurement results. 7.3 Calibration and verification
The microcoulometer should be calibrated frequently every day.
7.3.1 Calibration of microcoulometer
GB/T15959—1995
The electrolyte (4.14) in the titration cell must be replaced by about 70ml, and after stirring to stabilize EF, calibrate with 10.0rl chloride standard solution (4.13), and then inject 1μl, 2μl, 3μ, 4μ, 5l, 6μl, 7μl, 8, 9l and 10=l of hydrochloric acid solution (4.3) into the titration cell in turn to determine the amount of charge migration in each case. According to formula (1), a linear regression curve is drawn for the series of measurements. Q=aXQ +b
Where: Q: measured charge transfer amount, C: Q known charge transfer factor, C:
slope of the regression curve (electrolysis current efficiency); 3
force - intercept of the regression curve on the ordinate. The known charge amount can be obtained from formula (2).
Where: Vm - volume of hydrochloric acid solution, I.:co - actual concentration of hydrochloric acid solution, nol/L., F -: Faraday constant, F-96487C/mol.t13
7.3.2 Verification of the whole steps
Measure the A0x value of 10 pl, 20ul, 40μl, 60μl, 80ul of the standard solution (4.13) and follow the steps described in (5.2) or (5.3). Perform back analysis on the results of the measurement. The correlation coefficient is ≥0.999. To check the whole procedure, a standard solution with a medium concentration within the working range should be analyzed at each step. The difference between the measured value and the known value should not exceed 10%.
7.4 Blank determination
7.4.1 Blank of the whole procedure
The blank value of the whole procedure should not exceed 30gCI/1. If necessary, the adsorption step, the combustion step and the microcoulometric determination should be checked separately. Chemicals or other factors may cause the contamination of laboratory air with organic compounds. If the laboratory air is seriously polluted, even the dead volume of the stripping device can cause the result to be biased high. In order to prevent the determination result from being biased high, the activated carbon filter should not be sucked under any circumstances
If flocculants and filter aids are added, the blank of these materials will be determined. 7.4.2 Determine the blank according to (7.1.2.1)
Replace the water sample with 100ml of experimental water and follow the steps described in (7.1.2.1). 7.4.3 Determine the narrow
according to (7.1.2.2) Take 50ml of sodium nitrate washing solution, add 40~~50mg of activated carbon (4.1), and shake for 1h. Filter and wash the activated carbon according to the steps described in (7.1.2.2), and determine the content of organic fluorine. 8. Expression of results
Calculation method: Calculate the mass concentration of adsorbable organic halogen (AOX) by formula (3). ci
武Cr
I N+ N- N)
-The mass concentration of AOX is expressed as μgC1/L.1
N. —-empty value (according to 7.4.2), C:
measured value of strippable organic halogen, C:
N,——measured value of non-strippable organic halogen, C, M-
molar mass of chloride, M—35.46×10°g/mol; -volume of strippable sample, L:
GB/T 15959-1995
V, used for the volume of non-strippable sample, L; α and F have the same meaning as in formulas (1) and (2): if the companion crystal is not stripped, N, V, can be omitted. Note: The value measured by the second adsorption column is used to verify the degree of complete adsorption and is not included in the result. 9 Precision and Accuracy
Precision and uncertainty are shown in the table below.
Precision
Experimental case
Water sample
Drinking water
Surface water
Drinking water
Measured value
Water sample
Repeatability
Concentration accuracy
Relative standard deviation
Reproducibility
Standard deviation
Relative standard deviation
Reproducibility
Standard deviation
Relative standard deviation
Accuracy
Collective yield, %
1》Organic oxide wastewater, if the wastewater contains more suspended solids, when it is mixed again, it needs to be separated by high-speed centrifugation, and the supernatant is diluted and measured. A1 Adsorption performance of activated carbon
9—1995
GB/T15959
Appendix A
Performance and use of activated carbon
(Supplement)
Purchased activated carbon with appropriate adsorption capacity and low inorganic chloride content, or chromatographically pure activated carbon can be used for the determination of AOX.
Usage of activated carbon
Activated carbon easily adsorbs compounds (including other organic halogen compounds in the air), and it loses its activity after being exposed to the air for 5 days. In order to reduce the blank value of carbon, take more than 1.5 to 2.0 qualified activated carbon and place it in a sealed glass bottle for standby use (\day usage). Once the activated carbon in the sealed bottle is opened, it must be used on the same day, and the remaining cannot be used again. Additional remarks:
This standard is proposed by the Science and Technology Standards Department of the State Environmental Protection Administration. This standard is drafted by the Liaoning Provincial Environmental Protection Science Research Institute. The main drafters of this standard are Ye Yangxin, Liu Tao, Gong Dongjie and Yue Kezhi. The National Environmental Protection Administration is responsible for interpreting this standard.1 Connect the oxygen supply to the combustion quartz tube and the sulfuric acid drying and titration cell in the prescribed order and check that all interfaces are leak-proof, see figure.
Note: It is necessary to avoid the possible siphoning back of sulfuric acid into the combustion chamber when the temperature and pressure are reduced. 7.2.2 Adjust the oxygen flow rate to 150ml/min. 7.2.3 Slowly push the quartz boat into the preheating section of the combustion quartz tube to ensure that the activated carbon moisture is gradually dissipated. Note: The volume, residence time, temperature and gas flow rate of the quartz boat can affect the measurement results. 7.3 Calibration and verification
The microcoulometer should be calibrated regularly every day.
7.3.1 Calibration of microcoulombmeter
GB/T15959—1995
It is necessary to replace about 70ml of the electrolyte (4.14) in the titration cell, wait for the EF to be stabilized by stirring, and calibrate with 10.0rl of chloride standard solution (4.13), and then inject 1μl, 2μl, 3μ, 4μ, 5l, 6μl, 7μl, 8, 9l and 10=l of hydrochloric acid solution (4.3) into the titration cell in turn to determine the charge migration amount in each case. According to formula (1), a regression curve is drawn by linear regression method for the series of measurements. Q=aXQ +b
Where: Q: measured charge migration amount, C: Q known charge migration amount, C:
slope of the regression curve (electrolysis current efficiency); 3
force - intercept of the regression curve on the ordinate. The known charge can be obtained from formula (2).
Where: Vm is the volume of the hydrochloric acid solution, I.:co is the actual concentration of the hydrochloric acid solution, nol/L, F—: Faraday constant, F-96487C/mol.t13
7.3.2 Verification of the whole step
Measure the A0x value of 10 ul, 20ul, 40μl, 60μl, 80ul of the standard solution (4.13) and a blank, and operate according to the steps described in (5.2) or (5.3). The results of the determination are analyzed back to back. The correlation coefficient is ≥0.999. In order to verify the whole step, a standard solution with a medium concentration within the working range should be analyzed each time, and the difference between the actual measured value and the known value should not exceed 10%.
7.4 Blank determination
7.4.1 Blank value of the whole procedure
The blank value of the whole procedure shall not exceed 30gCI/1. If necessary, the adsorption step, combustion step and microcoulomb determination shall be checked separately. Chemicals or other factors may cause the pollution of laboratory air with organic compounds. If the laboratory air is seriously polluted, even the dead volume of the stripping device can cause the result to be biased high. In order to prevent the result from being biased high, the activated carbon filter shall not absorb the air under any circumstances.
If flocculants and filter aids are added, the blank of these materials will be determined. 7.4.2 Determine the blank according to (7.1.2.1)
Replace the water sample with 100ml of experimental water and operate according to the steps described in (7.1.2.1). 7.4.3 Determine the narrow
according to (7.1.2.2) Take 50ml of sodium nitrate washing solution, add 40~~50mg of activated carbon (4.1), and shake for 1h. Filter and wash the activated carbon according to the steps described in (7.1.2.2), and determine the content of organic fluorine. 8. Expression of results
Calculation method: Calculate the mass concentration of adsorbable organic halogen (AOX) by formula (3). ci
武Cr
I N+ N- N)
-The mass concentration of AOX is expressed as μgC1/L.1
N. —-empty value (according to 7.4.2), C:
measured value of strippable organic halogen, C:
N,——measured value of non-strippable organic halogen, C, M-
molar mass of chloride, M—35.46×10°g/mol; -volume of strippable sample, L:
GB/T 15959-1995
V, used for the volume of non-strippable sample, L; α and F have the same meaning as in formulas (1) and (2): if the companion crystal is not stripped, N, V, can be omitted. Note: The value measured by the second adsorption column is used to verify the degree of complete adsorption and is not included in the result. 9 Precision and Accuracy
Precision and uncertainty are shown in the table below.
Precision
Experimental case
Water sample
Drinking water
Surface water
Drinking water
Measured value
Water sample
Repeatability
Concentration accuracy
Relative standard deviation
Reproducibility
Standard deviation
Relative standard deviation
Reproducibility
Standard deviation
Relative standard deviation
Accuracy
Collective yield, %
1》Organic oxide wastewater, if the wastewater contains more suspended solids, when it is mixed again, it needs to be separated by high-speed centrifugation, and the supernatant is diluted and measured. A1 Adsorption performance of activated carbon
9—1995
GB/T15959
Appendix A
Performance and use of activated carbon
(Supplement)
Purchased activated carbon with appropriate adsorption capacity and low inorganic chloride content, or chromatographically pure activated carbon can be used for the determination of AOX.
Usage of activated carbon
Activated carbon easily adsorbs compounds (including other organic halogen compounds in the air), and it loses its activity after being exposed to the air for 5 days. In order to reduce the blank value of carbon, take more than 1.5 to 2.0 qualified activated carbon and place it in a sealed glass bottle for standby use (\day usage). Once the activated carbon in the sealed bottle is opened, it must be used on the same day, and the remaining cannot be used again. Additional remarks:
This standard is proposed by the Science and Technology Standards Department of the State Environmental Protection Administration. This standard is drafted by the Liaoning Provincial Environmental Protection Science Research Institute. The main drafters of this standard are Ye Yangxin, Liu Tao, Gong Dongjie and Yue Kezhi. The National Environmental Protection Administration is responsible for interpreting this standard.1 Connect the oxygen supply to the combustion quartz tube and the sulfuric acid drying and titration cell in the prescribed order and check that all interfaces are leak-proof, see figure.
Note: It is necessary to avoid the possible siphoning back of sulfuric acid into the combustion chamber when the temperature and pressure are reduced. 7.2.2 Adjust the oxygen flow rate to 150ml/min. 7.2.3 Slowly push the quartz boat into the preheating section of the combustion quartz tube to ensure that the activated carbon moisture is gradually dissipated. Note: The volume, residence time, temperature and gas flow rate of the quartz boat can affect the measurement results. 7.3 Calibration and verification
The microcoulometer should be calibrated regularly every day.
7.3.1 Calibration of microcoulombmeter
GB/T15959—1995
It is necessary to replace about 70ml of the electrolyte (4.14) in the titration cell, wait for the EF to be stabilized by stirring, and calibrate with 10.0rl of chloride standard solution (4.13), and then inject 1μl, 2μl, 3μ, 4μ, 5l, 6μl, 7μl, 8, 9l and 10=l of hydrochloric acid solution (4.3) into the titration cell in turn to determine the charge migration amount in each case. According to formula (1), a regression curve is drawn by linear regression method for the series of measurements. Q=aXQ +b
Where: Q: measured charge migration amount, C: Q known charge migration amount, C:
slope of the regression curve (electrolysis current efficiency); 3
force - intercept of the regression curve on the ordinate. The known charge can be obtained from formula (2).
Where: Vm is the volume of the hydrochloric acid solution, I.:co is the actual concentration of the hydrochloric acid solution, nol/L, F—: Faraday constant, F-96487C/mol.t13
7.3.2 Verification of the whole step
Measure the A0x value of 10 ul, 20ul, 40μl, 60μl, 80ul of the standard solution (4.13) and a blank, and operate according to the steps described in (5.2) or (5.3). The results of the determination are analyzed back to back. The correlation coefficient is ≥0.999. In order to verify the whole step, a standard solution with a medium concentration within the working range should be analyzed each time, and the difference between the actual measured value and the known value should not exceed 10%.
7.4 Blank determination
7.4.1 Blank value of the whole procedure
The blank value of the whole procedure shall not exceed 30gCI/1. If necessary, the adsorption step, combustion step and microcoulomb determination shall be checked separately. Chemicals or other factors may cause the pollution of laboratory air with organic compounds. If the laboratory air is seriously polluted, even the dead volume of the stripping device can cause the result to be biased high. In order to prevent the result from being biased high, the activated carbon filter shall not absorb the air under any circumstances.
If flocculants and filter aids are added, the blank of these materials will be determined. 7.4.2 Determine the blank according to (7.1.2.1)
Replace the water sample with 100ml of experimental water and operate according to the steps described in (7.1.2.1). 7.4.3 Determine the narrow
according to (7.1.2.2) Take 50ml of sodium nitrate washing solution, add 40~~50mg of activated carbon (4.1), and shake for 1h. Filter and wash the activated carbon according to the steps described in (7.1.2.2), and determine the content of organic fluorine. 8. Expression of results
Calculation method: Calculate the mass concentration of adsorbable organic halogen (AOX) by formula (3). ci
武Cr
I N+ N- N)
-The mass concentration of AOX is expressed as μgC1/L.1
N. —-empty value (according to 7.4.2), C:
measured value of strippable organic halogen, C:
N,——measured value of non-strippable organic halogen, C, M-
molar mass of chloride, M—35.46×10°g/mol; -volume of strippable sample, L:
GB/T 15959-1995
V, used for the volume of non-strippable sample, L; α and F have the same meaning as in formulas (1) and (2): if the companion crystal is not stripped, N, V, can be omitted. Note: The value measured by the second adsorption column is used to verify the degree of complete adsorption and is not included in the result. 9 Precision and Accuracy
Precision and uncertainty are shown in the table below.
Precision
Experimental case
Water sample
Drinking water
Surface water
Drinking water
Measured value
Water sample
Repeatability
Concentration accuracy
Relative standard deviation
Reproducibility
Standard deviation
Relative standard deviation
Reproducibility
Standard deviation
Relative standard deviation
Accuracy
Collective yield, %
1》Organic oxide wastewater, if the wastewater contains more suspended solids, when it is mixed again, it needs to be separated by high-speed centrifugation, and the supernatant is diluted and measured. A1 Adsorption performance of activated carbon
9—1995
GB/T15959
Appendix A
Performance and use of activated carbon
(Supplement)
Purchased activated carbon with appropriate adsorption capacity and low inorganic chloride content, or chromatographically pure activated carbon can be used for the determination of AOX.
Usage of activated carbon
Activated carbon easily adsorbs compounds (including other organic halogen compounds in the air), and it loses its activity after being exposed to the air for 5 days. In order to reduce the blank value of carbon, take more than 1.5 to 2.0 qualified activated carbon and place it in a sealed glass bottle for standby use (\day usage). Once the activated carbon in the sealed bottle is opened, it must be used on the same day, and the remaining cannot be used again. Additional remarks:
This standard is proposed by the Science and Technology Standards Department of the State Environmental Protection Administration. This standard is drafted by the Liaoning Provincial Environmental Protection Science Research Institute. The main drafters of this standard are Ye Yangxin, Liu Tao, Gong Dongjie and Yue Kezhi. The National Environmental Protection Administration is responsible for interpreting this standard.1) Describe the steps. 7.4.3 Determine the narrow range according to (7.1.2.2). Take 50 ml of sodium nitrate washing solution, add 40~~50 mg of activated carbon (4.1), and shake for 1 hour. Filter and wash the activated carbon according to the steps described in (7.1.2.2), and determine the content of organic fluorine. 8. Expression of results Calculation method: Calculate the mass concentration of adsorbable organic halogen (AOX) by formula (3). ci
武Cr
I N+ N- N)
-The mass concentration of AOX is expressed as μgC1/L.1
N. —-empty value (according to 7.4.2), C:
measured value of strippable organic halogen, C:
N,——measured value of non-strippable organic halogen, C, M-
molar mass of chloride, M—35.46×10°g/mol; -volume of strippable sample, L:
GB/T 15959-1995
V, used for the volume of non-strippable sample, L; α and F have the same meaning as in formulas (1) and (2): if the companion crystal is not stripped, N, V, can be omitted. Note: The value measured by the second adsorption column is used to verify the degree of complete adsorption and is not included in the result. 9 Precision and Accuracy
Precision and uncertainty are shown in the table below.
Precision
Experimental case
Water sample
Drinking water
Surface water
Drinking water
Measured value
Water sample
Repeatability
Concentration accuracy
Relative standard deviation
Reproducibility
Standard deviation
Relative standard deviation
Reproducibility
Standard deviation
Relative standard deviation
Accuracy
Collective yield, %
1》Organic oxide wastewater, if the wastewater contains more suspended solids, when it is mixed again, it needs to be separated by high-speed centrifugation, and the supernatant is diluted and measured. A1 Adsorption performance of activated carbon
9—1995
GB/T15959
Appendix A
Performance and use of activated carbon
(Supplement)
Purchased activated carbon with appropriate adsorption capacity and low inorganic chloride content, or chromatographically pure activated carbon can be used for the determination of AOX.
Usage of activated carbon
Activated carbon easily adsorbs compounds (including other organic halogen compounds in the air), and it loses its activity after being exposed to the air for 5 days. In order to reduce the blank value of carbon, take more than 1.5 to 2.0 qualified activated carbon and place it in a sealed glass bottle for standby use (\day usage). Once the activated carbon in the sealed bottle is opened, it must be used on the same day, and the remaining cannot be used again. Additional remarks:
This standard is proposed by the Science and Technology Standards Department of the State Environmental Protection Administration. This standard is drafted by the Liaoning Provincial Environmental Protection Science Research Institute. The main drafters of this standard are Ye Yangxin, Liu Tao, Gong Dongjie and Yue Kezhi. The National Environmental Protection Administration is responsible for interpreting this standard.1) Describe the steps. 7.4.3 Determine the narrow range according to (7.1.2.2). Take 50 ml of sodium nitrate washing solution, add 40~~50 mg of activated carbon (4.1), and shake for 1 hour. Filter and wash the activated carbon according to the steps described in (7.1.2.2), and determine the content of organic fluorine. 8. Expression of results Calculation method: Calculate the mass concentration of adsorbable organic halogen (AOX) by formula (3). ci
武Cr
I N+ N- N)
-The mass concentration of AOX is expressed as μgC1/L.1
N. —-empty value (according to 7.4.2), C:
measured value of strippable organic halogen, C:
N,——measured value of non-strippable organic halogen, C, M-
molar mass of chloride, M—35.46×10°g/mol; -volume of strippable sample, L:
GB/T 15959-1995
V, used for the volume of non-strippable sample, L; α and F have the same meaning as in formulas (1) and (2): if the companion crystal is not stripped, N, V, can be omitted. Note: The value measured by the second adsorption column is used to verify the degree of complete adsorption and is not included in the result. 9 Precision and Accuracy
Precision and uncertainty are shown in the table below.
Precision
Experimental case
Water sample
Drinking water
Surface water
Drinking water
Measured value
Water sample
Repeatability
Concentration accuracy
Relative standard deviation
Reproducibility
Standard deviation
Relative standard deviation
Reproducibility
Standard deviation
Relative standard deviation
Accuracy
Collective yield, %
1》Organic oxide wastewater, if the wastewater contains more suspended solids, when it is mixed again, it needs to be separated by high-speed centrifugation, and the supernatant is diluted and measured. A1 Adsorption performance of activated carbon
9—1995
GB/T15959
Appendix A
Performance and use of activated carbon
(Supplement)
Purchased activated carbon with appropriate adsorption capacity and low inorganic chloride content, or chromatographically pure activated carbon can be used for the determination of AOX.
Usage of activated carbon
Activated carbon easily adsorbs compounds (including other organic halogen compounds in the air), and it loses its activity after being exposed to the air for 5 days. In order to reduce the blank value of carbon, take more than 1.5 to 2.0 qualified activated carbon and place it in a sealed glass bottle for standby use (\day usage). Once the activated carbon in the sealed bottle is opened, it must be used on the same day, and the remaining cannot be used again. Additional remarks:
This standard is proposed by the Science and Technology Standards Department of the State Environmental Protection Administration. This standard is drafted by the Liaoning Provincial Environmental Protection Science Research Institute. The main drafters of this standard are Ye Yangxin, Liu Tao, Gong Dongjie and Yue Kezhi. The National Environmental Protection Administration is responsible for interpreting this standard.
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