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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB 2367-2006 Sodium nitrite for industrial use, and the following main technical changes have been made with respect to GB 2367-2006:
——The property of the standard is modified from mandatory to recommended;
——The index requirements of first-grade nitratine are a5djusted, and the index requirements of acceptable nitratine are cancelled (see 4.2 hereof, 3.2 of Edition 2006).
This standard was proposed by the China Petroleum and Chemical Industry Association.
This standard is under the jurisdiction of Subcommittee on Inorganic Chemical Industry of National Technical Committee on Chemical of Standardization Administration of China (SAC/TC 63/SC1).
The previous editions of this standard are as follows:
——GB 2367-1980, GB/T 2367-1990 and GB 2367-2006.
Sodium nitrite for industrial use
Warning——This product is classified as oxidizing substances in Class 5, Item 5.1 and toxic substances in Class 6, Item 6.1 according to GB 12268-2012, Clause 6, and shall be handled with care. The personnel using this standard shall have practice experiences in official laboratory. This standard does not purport to address all the safety concerns, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions.
1 Scope
This standard specifies the requirements, test methods, inspection rules, marking, labeling, packaging, transportation and storage of sodium nitrite for industrial use.
This standard is applicable to the sodium nitrite for industrial use. This product is mainly used as raw materials for manufacturing nitro compounds and azo dyes, mordant for fabric dyeing, bleach, metal heat treatment agent, cement early strength agent and antifreeze agent, etc.
2 Normative references
The following referenced documents are indispensable for the application of this standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB 190 Packing symbol of dangerous goods
GB/T 191-2008 Packaging—Pictorial marking for handling of goods
GB/T 3051-2000 Inorganic chemical products for industrial use—General method for determination of chloride content—Mercurimetric method
GB/T 6678 General principles for sampling chemical products
GB/T 6682 Water for analytical laboratory use—Specification and test methods
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
GB 12268-2012 List of dangerous goods
GB 12463-2009 General specifications for transport packages of dangerous goods
GB 15258 General rules for preparation of precautionary label for chemicals
HG/T 3696.1 Inorganic chemicals for industrial use—Preparations of standard and reagent solutions for chemical analysis—Part 1: Preparations of standard volumetric solutions
HG/T 3696.3 Inorganic chemicals for industrial use—Preparations of standard and reagent solutions for chemical analysis—Part 3: Preparations of reagent solutions
3 Molecular formula and relative molecular mass
Molecular formula: NaNO2
Relative molecular mass: 69.00 (according to international relative atomic mass in 2013)
4 Requirements
4.1 Appearance: White or microstrip light yellow crystals.
4.2 The sodium nitrite for industrial shall be tested with the methods specified in this standard, which shall meet those specified in Table 1.
Table 1
Item Index
Superior product First-grade product Acceptable product
Sodium nitrite (NaNO2) (by dry basis), ω/% ≥ 99.0 98.5 98.0
Nitratine (by dry basis), ω/% ≤ 0.8 1.3 —
Chloride (by NaCl) (by dry basis), ω/% ≤ 0.10 0.17 —
Insoluble matter (by dry basis), ω/% ≤ 0.05 0.06 0.10
Moisture, ω/% ≤ 1.4 2.0 2.5
Looseness a (by non-caking), ω/% ≥ 85
a The looseness index is the item controlled by adding anti-caking agent, which shall be inspected when required by users.
5 Test methods
5.1 General requirements
The reagents and water used in this standard refer to analytical reagents and the tertiary water specified in GB/T 6682 when no other requirements are specified. The standard titration solutions, preparations and products used in the test are prepared according to the regulations of HG/T 3696.1 and HG/T 3696.3 when no other requirements are specified.
5.2 Appearance inspection
Under natural light, the appearance is judged by visual method on the surface dish or white porcelain plate of white substrate.
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5.3 Determination of sodium nitrite content
5.3.1 Method summary
In acidic solution, sodium nitrite is oxidized with potassium permanganate. The sodium nitrite content is calculated according to the consumption of potassium permanganate standard titration solution.
5.3.2 Reagent
5.3.2.1 Sulfuric acid solution: 1+29. After preparing the sulfuric acid solution in proportion, heat it to about 70°C, drop potassium permanganate standard titration solution until the solution is light pink, and cool it.
5.3.2.2 Sulfuric acid solution: 1+5. After preparing the sulfuric acid solution in proportion, heat it to about 70°C, drop potassium permanganate standard titration solution until the solution is light pink, and cool it.
5.3.2.3 Potassium permanganate standard titration solution: c(1/5KMnO4)≈0.1 mol/L.
5.3.2.4 Sodium oxalate standard titration solution: c(1/2Na2C2O4) ≈0.1 mol/L per unit. The keeping time shall not more than 30d. The preparation, calibration and calculation shall be conducted according to the following methods:
a) Preparation: weigh about 6.7g of sodium oxalate and dissolve it in 300 mL of sulfuric acid solution (5.3.2.1), dilute it to 1000 mL with water and shake well.
b) Calibration: pipette 30.00 mL-35.00 mL of sodium oxalate titration solution [c (1/2Na2C2O4)≈0.1 mol/L], add 100 mL of sulfuric acid solution (8+92), titrate it with potassium permanganate standard titration solution, heated it to 65°C near the end point, and continue titrating it until the solution is light pink for 30s. Carry out the blank test at the same time.
c) Calculation: the accurate value (c) of the concentration of sodium oxalate standard titration solution, in mol/L, is calculated using Equation (1):
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(1)
where,
V1——the volume of potassium permanganate standard titration solution consumed during titration, mL;
V2——the volume of potassium permanganate standard titration solution consumed during titration blank test, mL;
c1——the accurate concentration of potassium permanganate standard titration solution, mol/L;
V——the volume of sodium oxalate standard titration solution pipetted for calibration, mL.
5.3.3 Analytical procedures
5.3.3.1 Preparation of test solution
Weigh 2.5g-2.7g of the specimen, accurate it to 0.000 2g, place it in a 250 mL beaker, and dissolve it with water. Transfer all to a 500 mL (V3) volumetric flask, dilute it to the scale with water, and shake well.
5.3.3.2 Determination
Drop about 38 mL-40 mL of potassium permanganate standard titration solution with a burette in a 300 mL conical flask. Add 25 mL (V4) of test solution with a pipette, add 10 mL of sulfuric acid solution (5.3.2.2) and heat it to 40°C. Add 10 mL (V2) of sodium oxalate standard titration solution with pipette, shake continuously to become clear solution, then heat it to 70°C -80°C, titrate it with potassium permanganate standard titration solution until the solution is light pink and does not disappear for 30s.
5.3.4 Result calculation
The sodium nitrite content is calculated as the mass fraction ω1 of sodium nitrite (NaNO2) using Equation (2):
Foreword i
1 Scope
2 Normative references
3 Molecular formula and relative molecular mass
4 Requirements
5 Test methods
6 Inspection rules
7 Marking and labeling
8 Packaging, transportation and storage
