PDF GB/T 10656-2022 English (GB/T 10656-2008: Older version)
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Analysis of water used in boiler and cooling system - Determination of zinc
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| GB/T 10656-2008 | English | 199 |
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Analysis of water used in boiler and cooling system -- Determination of zinc -- Zincon spectrophotometry
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| GB/T 10656-1989 | English | 199 |
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Analytical methods for boiler water and cooling water--Determination of zinc ion--Zincon spectrophotometry
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GB/T 10656-2022: PDF in English (GBT 10656-2022) GB/T 10656-2022
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 13.060.50;71.040.40
CCS G 76
Replacing GB/T 10656-2008
Analysis of water used in boiler and cooling system -
Determination of zinc
ISSUED ON: MARCH 09, 2022
IMPLEMENTED ON: OCTOBER 01, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions... 4
4 General ... 4
5 Zincon spectrophotometry ... 5
6 Complexometric titration ... 7
Analysis of water used in boiler and cooling system -
Determination of zinc
1 Scope
This document describes the determination of zinc in water used in boiler and cooling
system.
This document applies to the determination of zinc content ranging from 0.2 mg/L to
5.0 mg/L in water used in boiler and circulating cooling system.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this
document and are indispensable for its application. For dated references, only the
version corresponding to that date is applicable to this document; for undated references,
the latest version (including all amendments) is applicable to this document.
GB/T 601, Chemical reagent - Preparations of reference titration solutions
GB/T 602, Chemical reagent - Preparations of standard solutions for impurity
GB/T 603, Chemical reagent - Preparations of reagent solutions for use in test
methods
GB/T 6682-2008, Water for analytical laboratory use - Specification and test
methods
HG/T 4015, General Reagent - General method for the determination of pH ranges
corresponding the colour transition of acid-base indicators
3 Terms and definitions
There are no terms and definitions that need to be defined in this document.
4 General
Caution – The strong acid and strong base which are used in this document are
corrosive. Avoid inhalation or contact with the skin during use. If it splashes on
the body, use plenty of water to rinse immediately, and if it is serious, seek medical
attention immediately.
The reagents and water used in this document, unless otherwise specified, shall be
analytical reagents and above, and grade-3 water specified in GB/T 6682-2008.
The reference titration solutions, impurity reference solutions, reagents and products
required in the test shall be prepared in accordance with the provisions of GB/T 601,
GB/T 602 and GB/T 603 unless other provisions are specified.
5 Zincon spectrophotometry
5.1 Method summary
In the solution of pH8.5 ~ pH9.5, the zinc reagent and zinc ion form a blue complex; at
the wavelength of 620 nm, use the spectrophotometric method to measure its
absorbance.
5.2 Reagents or materials
5.2.1 Hydrochloric acid solution: 1+1.
5.2.2 Sulfuric acid solution: 1+35.
5.2.3 Sodium hydroxide solution: 40 g/L.
5.2.4 Ammonium persulfate solution: 4 g/L, ready-to-use.
5.2.5 Boric acid-potassium chloride-sodium hydroxide buffer solution (pH8.8 ~ pH9.0).
Prepare according to HG/T 4015.
5.2.6 Zinc standard stock solution: 0.1 mg/mL. Prepare according to GB/T 602, or buy
commercially available solution.
5.2.7 Zinc standard solution: 0.01 mg/mL. Pipette 10.00 mL of zinc standard stock
solution into a 100 mL volumetric flask; use water to dilute to the mark; mix well.
Formulate the solution when needed.
5.2.8 Methyl orange indicator solution: 1 g/L.
5.2.9 Zinc reagent solution: 0.8 g/L. Weigh 0.2 g of zinc reagent and dissolve it in 250
mL of absolute ethanol; cover and place overnight to make it completely dissolved (or
ultrasonically shake for 1 min ~ 5 min to dissolve completely). Store the solution in a
brown bottle and place it in a refrigerator at 0 °C ~ 4 °C for one month. When the
solution turns from red to yellow, it shall be re-prepared.
5.3 Apparatus
Spectrometer: equipped with a 2 cm absorption cell.
5.4 Test procedures
6.2.7 Acetic acid-sodium acetate buffer solution (pH = 5.5): Weigh 200 g of sodium
acetate (CH3COONa·3H2O) and dissolve it in 150 mL of water; add 9 mL of glacial
acetic acid; transfer it into a 1 000 mL volumetric flask; use water to dilute to the mark.
6.2.8 Ethylene Diamine Tetraacetic Acid standard titration solution: c(EDTA) = 0.001
mol/L. Before use, use boiled and cooled water to dilute the Ethylene Diamine
Tetraacetic Acid standard titration solution, of a concentration of 0.1 mol/L, which is
prepared according to GB/T 601.
6.2.9 Xylenol orange indicator solution: 6 g/L. Weigh 0.6 g of xylenol orange; dissolve
in water and dilute to 100 mL; mix well; store in a brown bottle.
6.3 Apparatus
Micro burette: 5 mL or 10 mL.
6.4 Preparation of samples
The sample for the single-item analysis measurement shall not be less than 300 mL; the
sample storage bottle shall be a stoppered glass bottle or a polyethylene plastic bottle.
The determination of zinc content should be completed as soon as possible. Under
normal circumstances, the sample shall not be stored for more than 24 h. For the
measurement of the content of soluble zinc, an appropriate amount of sample shall be
determined after filtration through the medium-speed filter paper.
6.5 Test procedure
Pipette 100.0 mL of sample; put it in a 250 mL conical flask; add 2 mL of tartaric acid
solution, 4 mL of potassium fluoride solution and 0.5 mL of thiourea solution; use
sodium hydroxide solution or hydrochloric acid solution to adjust the pH of the test
solution to 5 ~ 6. Then, add 20 mL of acetic acid-sodium acetate buffer solution; shake
well; heat to 30 °C ~ 40 °C on an electric hot plate or water bath. Add 10 drops of
trisodium citrate solution; then, add three to four drops of xylenol orange indicator
solution; use Ethylene Diamine Tetraacetic Acid standard titration solution to titrate
until the sample changes from purple red to bright yellow as the end point.
When there is no organic phosphonate in the sample, tartaric acid solution may not be
added; when there is no copper ion, thiourea solution may not be added; when the
content of aluminum ion and iron ion is less than 1 mg/L, trisodium citrate solution may
not be added.
6.6 Result calculation
The zinc ion content in the sample is calculated by mass concentration (ρ); the value is
expressed in milligrams per liter (mg/L), and calculated according to Formula (2):
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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