SY/T 5503-2024 Test method for chloride content in rock English, Anglais, Englisch, Inglés, えいご
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ICS
E
Professional standard of the People's Republic of China
SY/T 5503-2024
Replaces SY/T 5503-2009
Test method for chloride content in rock
岩石氯盐含量测定方法
(English Translation)
Issue date: 2024-12-25 Implementation date: 2025-06-25
Issued by National Development and Reform Commission, P.R.C
Contents
Foreword
1 Scope
2 Normative References
3 Terms and Definitions
4 Principle
5 Reagents and Solutions
5.1 Reagents
5.2 Solutions
5.3 Reference Materials
6 Instruments and Equipment
7 Sample and Sample Pre-treatment
8 Test Procedure and Data Processing
8.1 Silver Nitrate Titration Method
8.2 Ion Chromatography Method
8.3 Coulometric Method
9 Precision and Numerical Rounding
9.1 Repeatability
9.2 Reproducibility
9.3 Numerical Rounding
10 Contents and Format of Raw Data Records and Reports
Appendix A (Informative) Raw Data Record for Rock Chloride Salt Content
Appendix B (Informative) Analysis Report for Rock Chloride Salt Content
Determination Method for Chloride Salt Content in Rock
Warning — Personnel using this document should have practical experience in formal laboratory work. This document does not address all possible safety concerns. It is the responsibility of the user to adopt appropriate safety and health measures and to ensure compliance with conditions stipulated by relevant national regulations.
1 Scope
This document describes the principles, experimental procedures, and data processing methods for determining chloride salt content in rock using silver nitrate titration, ion chromatography, and coulometric methods.
This document applies to the determination of chloride salt content in rock.
2 Normative References
The following documents contain provisions which, through normative reference in this text, constitute essential provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
JJG 823 Verification Regulation for Ion Chromatographs
3 Terms and Definitions
No terms and definitions are required for this document.
4 Principle
A rock sample of a certain mass is soaked, dissolved, and filtered using deionized water. The chloride ion content in the dissolved solution is measured by an instrument, and then the chloride salt content of the rock sample is calculated.
a)Principle of silver nitrate titration method: The salt solution dissolved from the rock sample is titrated with a standard silver nitrate solution, using potassium chromate as an indicator. Silver ions react with chloride ions to form a white precipitate. Excess silver ions react with the potassium chromate indicator to form a brick-red silver chromate precipitate. The chloride ion content is calculated based on the consumption of silver nitrate. The reaction equation is as follows:
b)Principle of ion chromatography method: Ion chromatography is a type of liquid chromatography. The mobile phase for anion chromatography is an alkaline eluent, and the stationary phase is a separation column packed with anion exchange resin. When the saline aqueous solution is injected into the ion chromatograph, the sample is flushed into the separation column with the eluent. Anions in the solution are adsorbed by the anion exchange resin packed in the separation column. Different anions have different degrees of adsorption by the resin. Under the elution of the eluent, the ions are eluted sequentially and then enter the conductivity detector to measure their conductivity values. The chloride ion content is determined using the external standard method: Under the same chromatographic conditions, the retention time of the chloride ion standard solution is consistent with that of the chloride ion in the sample, allowing qualitative identification as the chloride peak. The peak area is proportional to the chloride ion concentration, enabling quantitative determination of the chloride ion content in the aqueous solution, which is then converted to the chloride salt content per kilogram of rock sample.
c)Principle of coulometric method: After the saline aqueous solution is injected into the titration cell, chloride ions react with silver ions generated by electrolysis from the silver electrode. The endpoint of the reaction is indicated by electrochemical analysis. By measuring the charge consumed during electrolysis, the amount of silver ions is calculated based on Faraday's law, thereby determining the chloride salt content in the solution.
Note: The chloride salts in rock referred to in this document are the water-soluble chlorides present in the rock, including sodium chloride, magnesium chloride, calcium chloride, etc. Their content is calculated by converting all into the equivalent amount of sodium chloride.
5 Reagents and Solutions
Note: Unless otherwise specified, reagents of analytical grade or higher shall be used in the analysis.
5.1 Reagents
5.1.1 Deionized water: Conductivity (25℃) ≤ 0.01 mS/m.
5.1.2 Potassium chromate (K₂CrO₄).
5.1.3 Silver nitrate (AgNO₃).
5.1.4 Aluminum potassium sulfate [KAl(SO₄)₂·12H₂O].
5.1.5 Borax (Na₂B₄O₇·10H₂O).
5.1.6 Dilute nitric acid (HNO₃): Concentration 5%.
5.1.7 Hydrogen peroxide (H₂O₂): Concentration 30%.
5.1.8 Glacial acetic acid (CH₃COOH).
5.1.9 Eluent: Prepare according to the requirements of the instrument model and column manual; preparation may be omitted if not needed.
5.1.10 Regenerant: Prepare according to the requirements of the instrument manual; preparation may be omitted if not needed.
5.2 Solutions
5.2.1 Borax solution: Concentration 50 g/L.
Weigh 5 g of borax, dissolve it in 100 ml of deionized water, and mix well.
5.2.2 Electrolyte solution: Concentration 70%.
Measure 700 ml of glacial acetic acid using a 1000 ml graduated cylinder and place it into a beaker. Measure 300 ml of deionized water using a 500 ml graduated cylinder and add it to the beaker. Mix thoroughly.
5.2.3 Sodium chloride standard solution: c(NaCl) = 0.0141 mol/L.
Prepare the sodium chloride standard solution using sodium chloride reference material as follows:
a) Place sodium chloride in a crucible and ignite it in a high-temperature furnace at 500℃~600℃ for 40 min~50 min. Cool it to room temperature in a desiccator.
b) Accurately weigh 0.8240 g of sodium chloride using a balance, place it in a beaker, dissolve it with a small amount of deionized water, transfer it completely into a 1000 ml volumetric flask, dilute to the mark, and mix well.
The concentration of this solution is c(NaCl) = 0.0141 mol/L. This standard solution is equivalent to a chloride content of 500 mg/L (calculated as chloride ion).
5.2.4 Silver nitrate standard solution: c(AgNO₃) = 0.0141 mol/L.
Preparation of silver nitrate solution: Weigh 2.3950 g of silver nitrate, dissolve it in 1000 ml of deionized water, store it in a brown ground-glass stoppered reagent bottle, and use it after standardization.
Standardize the silver nitrate standard solution by following these steps:
a)Use a 10 ml pipette to transfer 10.00 ml of the sodium chloride standard solution (5.2.3) into each of three Erlenmeyer flasks. Place 10.00 ml of deionized water into another Erlenmeyer flask as a blank test.
b) Add 5 drops (approximately 0.2 ml) of potassium chromate solution (5.2.5) to each flask as an indicator. Titrate with the silver nitrate solution to be standardized until the appearance of a brick-red precipitate indicates the endpoint. Record the consumption volume of the silver nitrate solution as V₂. Titrate the blank solution simultaneously and record the consumption volume of the silver nitrate solution as V₁. Calculate the concentration of the silver nitrate standard solution using Formula (1):
The average concentration from three standardizations is taken as the concentration of the silver nitrate standard solution. The absolute deviation among the three concentrations shall not exceed 0.0004 mol/L; otherwise, re-standardization is required. The silver nitrate solution should be stored protected from light and standardized once a month during use.
5.2.5 Potassium chromate solution: Concentration 5%.
Weigh 5 g of potassium chromate, dissolve it in a small amount of deionized water. Add silver nitrate solution (5.2.4) until a brick-red precipitate forms, mix well, let stand for 12 h, then filter. Dilute the filtrate with deionized water to 100 ml.
5.3 Reference Materials
5.3.1 Sodium chloride (NaCl): Reference material with a certified mass fraction of 99.99%.
5.3.2 Chloride ion solution reference material: Chloride ion reference material with a certified value of 1000 μg/ml.
6 Instruments and Equipment
6.1 Balance: Sensitivity 0.1 mg.
6.2 Graduated cylinders: 500 ml, 1000 ml.
6.3 Crucible.
6.4 High-temperature furnace: Room temperature ~ 800℃, ±1℃.
6.5 Desiccator.
6.6 Volumetric flasks: 250 ml, 1000 ml.
6.7 Brown ground-glass stoppered reagent bottle: 2500 ml.
6.8 Pipettes: 10 ml, 50 ml, 100 ml.
6.9 Erlenmeyer flask: 100 ml.
6.10 Mortar and pestle.
