Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed to implement Environmental Protection Law of the People's Republic of China and Law of the People's Republic of China on Prevention and Control of Water Pollution, protect the environment, guarantee human health and standardize the monitoring method for chemical oxygen demand in water body.
This standard specifies the dichromate method for chemical oxygen demand in water.
This standard is applicable to the determination of the chemical oxygen demand in surface water, domestic sewage and industrial wastewater.
This Standard is a revision of GB 11914-89 Water Quality - Determination of the Chemical Oxygen Demand - Dichromate Method.
GB 11914-89 Water Quality - Determination of the Chemical Oxygen Demand - Dichromate Method was firstly issued in 1989; the drafting organization of the original standard is Beijing Chemical Industry Research Institute. This standard is revised for the first time mainly concerning the following items:
——to reduce the sampling volume by one half to diminish the environmental pollution brought about during sample determination;
——to change the mercury sulfate solid into solution to cover up the chlorid, which is easier for operation;
——to modify the adding amount of mercury sulfate which was 0.4g so that it can be added in proportion to the chloride ion in the sample, the content of which may be determined or roughly judged prior to adding, with a view to diminishing the application of toxic substance mercury sulfate.
——to add Annex A for rough judgement of chloride ion concentration with silver nitrate method;
——to specify the detection limit and lower limit of determination for the method and to define the reservation of significant figures in the calculation result;
——to add chapters of "Interference and Elimination" and "Quality Assurance and Control".
The original standard GB 11914-89 Water Quality - Determination of the Chemical Oxygen Demand - Dichromate Method approved and issued on December 25, 1989 by Environmental Protection Agency of the nation is abolished from the implementation date of this standard.
Annex A of this standard is informative.
This standard is organized and formulated by the Department of Environment Monitoring and Department of Science, Technology and Standards under the Ministry of Environmental Protection.
This standard was approved by the Ministry of Environmental Protection of the People's Republic of China on March 30, 2017.
This standard is implemented as of May 1, 2017.
The Ministry of Environmental Protection is responsible for the explanation of this standard.
Water Quality - Determination of the Chemical Oxygen Demand - Dichromate Method
Warning: the reagent mercury sulfate adopted for the purpose of this method is virulent, so the experiment personnel shall avoid direct contact with it and the sample preparation process shall be carried out in a fuming cupboard.
1 Application Scope
This standard specifies the dichromate method for determination of chemical oxygen demand in water.
This standard is applicable to determination of the chemical oxygen demand in surface water, domestic sewage and industrial wastewater while not applicable to that in water with chlorid concentration greater than 1,000 mg/L (after dilution).
When the sampling volume is 10.0 ml, the detection limit for this method is 4 mg/L and the lower limit of determination is 16 mg/L. As for water sample without dilution, the upper limit is 700 mg/L. If such limit is exceeded, the sample must be diluted before determination.
2 Normative References
The provisions in the following documents are referenced for the purpose of this standard. For undated references, the valid versions shall apply.
GB 11896 Water Quality - Determination of Chloride - Silver Nitrate Titration Method
GB 17378.4 The Specification for Marine Monitoring - Part 4: Seawater Analysis
HJ 506 Water Quality - Determination of Dissolved Oxygen - Electrochemical Probe Method
HJ/T 91 Technical Specifications Requirements for Monitoring of Surface Water and Waste Water
3 Terms and Definitions
For the purpose of this document, the following term and definition applies.
3.1
chemical oxygen demand (CODCr )
the mass concentration (expressed in mg/L) of oxygen corresponding to the dichromate consumed by the dissolved solids and suspended substances in the water sample during oxidation treatment by potassium dichromate under certain conditions
4 Method Principle
Put in the potassium dichromate solution with known quantity in the water sample, taking the silver salt as catalyst in strong acid media, then subject it to boil reflux, after which titrate the unreduced potassium dichromate with ammonium ferrous sulfate, for which the ferroin is taken as the indicator. Calculate the mass concentration of oxygen consumed with the amount of potassium dichromate consumed.
Notes:
1 In acidic potassium dichromate, the aromatic hydrocarbon and pyridine is difficult to be oxidized with low oxidation ratio. With the catalytic action of silver sulfate, straight-chain aliphatic compound can be oxidized effectively.
2 Inorganic reducing substances such as nitrite, sulfide and divalent ferric salt will augment the determination result as the oxygen demand of the said substances is also a part of CODCr.
5 Interference and Elimination
Main interferential substance in respect of this method is chlorid, which may be removed by adding mercury sulfate solution. After reflux, chloride ion can combine with mercury sulfate into soluble chlorine-mercury complex. The dosage of mercury sulfate solution may be determined according to its mass ratio to the content of chloride ion in water sample (the proportion m[HgSO4]: m [Cl-] ≥ 20:1), with its adding amount not exceeding 2 ml (calculated with the maximum allowable concentration of chloride ion as 1,000 mg/L). The content of chloride ion in water sample may be determined or roughly judged according to Annex A of GB 11896 or HJ 506 or this standard, or obtained by conversion according to Annex A of HJ 506 after determination of the conductivity, or obtained by conversion after salinity determination according to GB 17378.4.
6 Reagents and Materials
Unless otherwise specified, analytically pure reagents complying with national standard and newly-prepared ultrapure water, distilled water or water with equivalent purity are adopted for the purpose of the test.
6.1 Sulfuric acid (H2SO4), ρ=1.84 g/ml, guaranteed reagent.
6.2 Potassium dichromate(K2Cr2O7): reference reagent; take proper amount of potassium dichromate and dry it to constant weight in an oven at 105℃.
Foreword i
1 Application Scope
2 Normative References
3 Terms and Definitions
4 Method Principle
5 Interference and Elimination
6 Reagents and Materials
7 Instruments and Equipment
8 Samples
9 Analysis Procedures
10 Calculation and Expression of Test Results
11 Precision and Accuracy
12 Quality Assurance and Quality Control
13 Waste Treatment
14 Attentions
Annex A (Informative) Rough Judgment Method for Chlorine Ion Content
Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed to implement Environmental Protection Law of the People's Republic of China and Law of the People's Republic of China on Prevention and Control of Water Pollution, protect the environment, guarantee human health and standardize the monitoring method for chemical oxygen demand in water body.
This standard specifies the dichromate method for chemical oxygen demand in water.
This standard is applicable to the determination of the chemical oxygen demand in surface water, domestic sewage and industrial wastewater.
This Standard is a revision of GB 11914-89 Water Quality - Determination of the Chemical Oxygen Demand - Dichromate Method.
GB 11914-89 Water Quality - Determination of the Chemical Oxygen Demand - Dichromate Method was firstly issued in 1989; the drafting organization of the original standard is Beijing Chemical Industry Research Institute. This standard is revised for the first time mainly concerning the following items:
——to reduce the sampling volume by one half to diminish the environmental pollution brought about during sample determination;
——to change the mercury sulfate solid into solution to cover up the chlorid, which is easier for operation;
——to modify the adding amount of mercury sulfate which was 0.4g so that it can be added in proportion to the chloride ion in the sample, the content of which may be determined or roughly judged prior to adding, with a view to diminishing the application of toxic substance mercury sulfate.
——to add Annex A for rough judgement of chloride ion concentration with silver nitrate method;
——to specify the detection limit and lower limit of determination for the method and to define the reservation of significant figures in the calculation result;
——to add chapters of "Interference and Elimination" and "Quality Assurance and Control".
The original standard GB 11914-89 Water Quality - Determination of the Chemical Oxygen Demand - Dichromate Method approved and issued on December 25, 1989 by Environmental Protection Agency of the nation is abolished from the implementation date of this standard.
Annex A of this standard is informative.
This standard is organized and formulated by the Department of Environment Monitoring and Department of Science, Technology and Standards under the Ministry of Environmental Protection.
This standard was approved by the Ministry of Environmental Protection of the People's Republic of China on March 30, 2017.
This standard is implemented as of May 1, 2017.
The Ministry of Environmental Protection is responsible for the explanation of this standard.
Water Quality - Determination of the Chemical Oxygen Demand - Dichromate Method
Warning: the reagent mercury sulfate adopted for the purpose of this method is virulent, so the experiment personnel shall avoid direct contact with it and the sample preparation process shall be carried out in a fuming cupboard.
1 Application Scope
This standard specifies the dichromate method for determination of chemical oxygen demand in water.
This standard is applicable to determination of the chemical oxygen demand in surface water, domestic sewage and industrial wastewater while not applicable to that in water with chlorid concentration greater than 1,000 mg/L (after dilution).
When the sampling volume is 10.0 ml, the detection limit for this method is 4 mg/L and the lower limit of determination is 16 mg/L. As for water sample without dilution, the upper limit is 700 mg/L. If such limit is exceeded, the sample must be diluted before determination.
2 Normative References
The provisions in the following documents are referenced for the purpose of this standard. For undated references, the valid versions shall apply.
GB 11896 Water Quality - Determination of Chloride - Silver Nitrate Titration Method
GB 17378.4 The Specification for Marine Monitoring - Part 4: Seawater Analysis
HJ 506 Water Quality - Determination of Dissolved Oxygen - Electrochemical Probe Method
HJ/T 91 Technical Specifications Requirements for Monitoring of Surface Water and Waste Water
3 Terms and Definitions
For the purpose of this document, the following term and definition applies.
3.1
chemical oxygen demand (CODCr )
the mass concentration (expressed in mg/L) of oxygen corresponding to the dichromate consumed by the dissolved solids and suspended substances in the water sample during oxidation treatment by potassium dichromate under certain conditions
4 Method Principle
Put in the potassium dichromate solution with known quantity in the water sample, taking the silver salt as catalyst in strong acid media, then subject it to boil reflux, after which titrate the unreduced potassium dichromate with ammonium ferrous sulfate, for which the ferroin is taken as the indicator. Calculate the mass concentration of oxygen consumed with the amount of potassium dichromate consumed.
Notes:
1 In acidic potassium dichromate, the aromatic hydrocarbon and pyridine is difficult to be oxidized with low oxidation ratio. With the catalytic action of silver sulfate, straight-chain aliphatic compound can be oxidized effectively.
2 Inorganic reducing substances such as nitrite, sulfide and divalent ferric salt will augment the determination result as the oxygen demand of the said substances is also a part of CODCr.
5 Interference and Elimination
Main interferential substance in respect of this method is chlorid, which may be removed by adding mercury sulfate solution. After reflux, chloride ion can combine with mercury sulfate into soluble chlorine-mercury complex. The dosage of mercury sulfate solution may be determined according to its mass ratio to the content of chloride ion in water sample (the proportion m[HgSO4]: m [Cl-] ≥ 20:1), with its adding amount not exceeding 2 ml (calculated with the maximum allowable concentration of chloride ion as 1,000 mg/L). The content of chloride ion in water sample may be determined or roughly judged according to Annex A of GB 11896 or HJ 506 or this standard, or obtained by conversion according to Annex A of HJ 506 after determination of the conductivity, or obtained by conversion after salinity determination according to GB 17378.4.
6 Reagents and Materials
Unless otherwise specified, analytically pure reagents complying with national standard and newly-prepared ultrapure water, distilled water or water with equivalent purity are adopted for the purpose of the test.
6.1 Sulfuric acid (H2SO4), ρ=1.84 g/ml, guaranteed reagent.
6.2 Potassium dichromate(K2Cr2O7): reference reagent; take proper amount of potassium dichromate and dry it to constant weight in an oven at 105℃.
Contents of HJ 828-2017
Foreword i
1 Application Scope
2 Normative References
3 Terms and Definitions
4 Method Principle
5 Interference and Elimination
6 Reagents and Materials
7 Instruments and Equipment
8 Samples
9 Analysis Procedures
10 Calculation and Expression of Test Results
11 Precision and Accuracy
12 Quality Assurance and Quality Control
13 Waste Treatment
14 Attentions
Annex A (Informative) Rough Judgment Method for Chlorine Ion Content
