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GB/T 16496-1996Chemical reagent. Potassium sulfate (English PDF)

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Issued by

State Bureau of Quality and Technical Supervision

Level / Type

National · Recommended

Issue date

August 22, 1996

Implementation date

February 1, 1997

Scope

GB/T 16496-1996 (Chemical reagent. Potassium sulfate) is available as an English-translated PDF.

GB/T 16496-1996 — This Standard specifies the technical requirements, test methods, inspection rules, and packaging and marking for the chemical reagent - potassium sulfate.

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Document preview — GB/T 16496-1996

National Standard of the People's Republic of China

ICS: 71.040.30
Classification: G 62

Issued by: State Bureau of Quality and Technical Supervision

Foreword...3
1 Scope...5
2 Normative references...5
3 Characteristics...6
4 Specification...6
5 Tests...6
6 Inspection rules...10
7 Packaging and marks...10

Foreword

This Standard specifies two grades. analytically pure reagents (AR) and chemically

pure reagents (CP). The analytically pure reagent is equivalent to R 85 "Potassium

Sulfate" as specified in ISO 6353-3.1987 "Reagents for chemical analysis -- Part 3.

Specifications -- Second series". The differences are as follows.

1 Standard drafting

In light of China's specific conditions, this Standard includes three additional chapters

covering characteristics, inspection rules, packaging and marking.

2 Specification

2.1 Items

Compared to the international standard, this Standard includes two additional items.

clarity test and water-insoluble matter.

2.2 Indicators

The specifications for iron and arsenic in the analytically pure reagent are stricter than

international standards, while all other items match international standards.

3 Tests

The methods for determining content in this Standard are identical to those in the

international standard. Regarding calcium determination, while the international

standard employs atomic absorption spectrometry, this Standard adopts the colorimetric

method using a calcium reagent, as it is more convenient to implement. For other

parameters, the corresponding standards from the established Chinese series of general

test methods for chemical reagents are cited; this series was formulated primarily based

on ISO 6353-1.1982 "Reagents for chemical analysis -- Part 1.General test methods".

This Standard was formulated based on HG 3-920-76 "Chemical reagent -- Potassium

sulfate". Compared to the previous version, corresponding changes have been made to

the specifications and test methods in order to align with international standards.

As of the effective date of this Standard, the former Ministry of Chemical Industry

standard HG 3-920-76 is superseded.

Annex A of this Standard is a normative annex.

This Standard was proposed by Ministry of Chemical Industry of the People's Republic

of China.

This Standard shall be under the jurisdiction of Beijing Chemical Reagent General

Factory.

The drafting organizations of this Standard. Chengdu Chemical Reagent Factory.

Main drafters of this Standard. Chen Junru, Guo Shanpei.

Chemical reagent -- Potassium sulfate

Molecular formula. K2SO4

Relative molecular mass. 174.26

1 Scope

This Standard specifies the technical requirements, test methods, inspection rules, and

packaging and marking for the chemical reagent - potassium sulfate.

2 Normative references

The following standards contain provisions which, through reference in this Standard,

constitute provisions of this Standard. At the time of publication, the editions indicated

are valid. All standards are subject to revision. The parties who are using this Standard

shall explore the possibility of using the latest version of the following standards.

GB/T 601-88, Chemical Reagent -- Preparations of Standard Volumetric Solutions

GB/T 602-88, Chemical Reagent -- Preparations of Reagent Solution for Use in Test

GB/T 603-88, Chemical Reagent -- Preparation of reagents and products used in the

test methods

GB/ T 609-88, Chemical Reagent -- General method for the determination of total

nitrogen (idt ISO 6353-1.1982)

GB/T 610.2-88, Chemical Reagent -- General method for the determination of

arsenic (silver diethyldithiocarbamate method) (eqv ISO 6353.1982)

GB/T 619-88, Chemical Reagent -- Sampling and acceptance rules

GB 6682-92, Specifications and test methods for analytical laboratory water (eqv

ISO 3696.1987)

GB/ T 9723- 88, Chemical Reagent -- General rules for flame atomic absorption

spectrometry

GB/T 9724-88, Chemical Reagent -- General rules for pH determination (eqv ISO

6353-1.1982)

GB/T 9729-88, Chemical Reagent -- General method for the determination of

chloride (eqv ISO 6353-1.1982)

GB/ T 9735-88, Chemical Reagent -- General methods for the determination of

heavy metals (eqv ISO 6353-1.1982)

GB/ T 9738-88, Chemical Reagent -- General method for the determination of water-

insoluble matter (eqv ISO 6353-1.1982)

GB/T 9739-88, Chemical Reagent -- General method for the determination of iron

(eqv ISO 6353-1.1982)

GB 15346-94, Chemical Reagent -- Packaging and marks

HG 3-1168-78, Chemical Reagent -- Preparation and determination methods for

clarity standards

3 Characteristics

This reagent is a colorless, transparent crystalline substance or powder that is soluble

in water.

4 Specification

The specifications for potassium sulfate shall comply with the requirements of Table 1.

Table 1

5 Tests

Unless otherwise specified in this chapter, the standard titration solutions, standard

solutions, reagents, and preparations used shall be prepared in accordance with GB/T

601, GB/T 602, and GB/T 603; the water used for experiments shall meet the

Name

Clarity test

Analytically pure Chemically pure

Content (K2SO4), %

Water-insoluble matter, %

Chloride (Cl), %

Total nitrogen content (N), %

Sodium (Na), %

Calcium (Ca), %

Iron (Fe), %

Arsenic (As), %

Heavy metal (calculated as Pb), %

Qualified Qualified

specifications for Grade 3 water as defined in GB 6682-92; and samples shall be

weighed to an accuracy of 0.01 g.

5.1 Content

Weigh 0.3 g of the sample to the nearest 0.0001 g and dissolve it in 30 mL of water.

Load the solution onto a strongly acidic cation-exchange resin column. Refer to Annex

A (normative) for resin treatment and regeneration procedures. Perform the ion

exchange at a flow rate of approximately 5 mL/min, collecting the effluent in a conical

flask. Wash the resin with water in portions until the eluate is neutral, collecting both

the effluent and the washings. Add 2 drops of phenolphthalein indicator solution (10

g/L). Titrate with a standard sodium hydroxide solution [c(NaOH) = 0.1 mol/L] until

the solution turns pink and remains so for 30 seconds. Conduct a blank test concurrently.

The content is calculated using the following formula.

Where,

X - mass percentage of potassium sulfate, %;

V1 - volume of the standard sodium hydroxide titration solution, mL;

V2 - volume of the standard sodium hydroxide titration solution used in the blank test,

mL;

c - concentration of the standard sodium hydroxide titration solution, mol/L;

87.13 - molar mass of potassium sulfate [M(1/2 K2SO4)], g/mol;

m - mass of the sample, g.

5.2 pH

Determine in accordance with GB/T 9724.

5.3 Clarity test

Weigh 5 g of the sample and dissolve it in 100 mL of water. Its turbidity shall not exceed

the following clarity standards specified in HG/T 3-1168-78.

5.4 Water-insoluble matter

Analytically pure

Chemically pure

No. 2;

No. 4.

Weigh 20 g of the sample and dissolve it in 400 mL of water. After maintaining the

temperature in a water bath for 1 h, perform the determination in accordance with GB/T

9738.

5.5 Chloride

Weigh 2 g of the sample and dissolve it in 20 mL of water. Perform the determination

in accordance with GB/T 9729.The turbidity of the solution shall not exceed that of the

standard comparison solution.

To prepare the standard comparison solution, take a quantity of chloride standard

solution containing the following amount.

Process in the same manner and at the same time as the sample.

5.6 Total nitrogen content

Weigh 2 g of the sample and dissolve it in 140 mL of water. Perform the determination

in accordance with GB/T 609.The yellow color of the solution shall not be more intense

than that of the standard comparison solution.

To prepare the standard comparison solution, take a nitrogen standard solution

containing the following amount.

Process in the same manner and at the same time as the sample.

5.7 Sodium

Determine in accordance with GB/T 9723.

5.7.1 Instrumental conditions

Light source. sodium hollow cathode lamp;

Wavelength. 589.0 nm;

Flame. acetylene-air.

5.7.2 Determination method

Weigh 1 g of the sample, dissolve it in water, and dilute to 100 mL. Take four 10 mL

Analytically pure

Chemically pure.

Analytically pure

Chemically pure.

aliquots (or 2 mL aliquots for chemically pure grade). Perform the determination in

accordance with the provisions of 6.2.2 of GB/T 9723-88.

5.8 Calcium

Weigh 0.5 g of the sample, dissolve it in water, and dilute to 100 mL. Pipette 10 mL of

the solution and add 10 mL of 95% ethanol, 0.5 mL of mixed alkali solution, and 1 mL

of glyoxal-bis(2-hydroxyanil) ethanol solution (2 g/L). Mix well and let stand for 5 min.

Extract with 5 mL of chloroform (at a temperature not exceeding 30°C) and

immediately perform a colorimetric comparison. The red color of the organic layer shall

not be more intense than that of the standard comparison solution.

To prepare the standard comparison solution, take a calcium standard solution

containing the following amount.

Dilute to 10 mL and treat simultaneously and in the same manner as an equal volume

of the test solution.

5.9 Iron

Weigh 2 g of the sample and dissolve it in 15 mL of water. Adjust the pH of the solution

to 2 using hydrochloric acid solution (15%), then perform the determination in

accordance with GB/T 9739.The red color of the solution shall not be more intense

than that of the standard comparison solution.

To prepare the standard comparison solution, take an amount of iron standard solution

containing the following quantity.

Process in the same manner and at the same time as the sample.

5.10 Arsenic

Weigh 2 g of the sample and dissolve it in 25 mL of water. Transfer the solution to an

arsenic determination flask. Proceed with the determination in accordance with GB/T

610.2 The purple-red color of the absorbing solution shall not be more intense than that

of the standard comparison solution.

To prepare the standard comparison solution, take an amount of arsenic standard

solution containing the following amounts.

Analytically pure

Chemically pure.

Analytically pure

Chemically pure.

Analytically pure

Chemically pure

Process in the same manner and at the same time as the sample.

5.11 Heavy metal

Weigh 3 g of the sample, dissolve it in water, and dilute to 30 mL. Take a 25 mL and

add 0.2 mL of acetic acid solution (30%). Perform the determination in accordance with

GB/T 9735.The color of the solution shall not be darker than that of the standard

comparison solution.

To prepare the standard comparison solution, take the remaining 5 mL of the test

solution and the lead standard solution containing the following amounts.

Dilute to 25 mL and treat simultaneously and in the same manner as an equal volume

of the test solution.

6 Inspection rules

Sampling and acceptance shall be conducted in accordance with GB/T 619.

7 Packaging and marks

Packaging, storage, and transportation shall be carried out in accordance with GB 15346,

and appropriate marks shall be applied, wherein.

Packaging unit. Class 4;

Inner packaging types. NB-4, NBY-4, NB-5, NBY-5, NB-7, NB-8, NB-10, NB-11, NB-

13, NB-15;

Isolation materials. GC-2, GC-3;

Outer packaging types. WB-1, WB-2, WB-3.

Analytically pure

Chemically pure.

Annex A

(normative)

Treatment and regeneration methods for strongly acidic cation exchange resins

A1 Instruments

A1.1 Ion-exchange column material. glass or polyethylene tubing.

A1.2 Exchange column inner diameter. 10 mm~20 mm.

A1.3 Resin bed height. approximately 400 mm (the volume of the expanded resin

occupies two-thirds of the exchange column height).

A1.4 Resin particle size. 0.2 mm~0.8 mm.

A2 Processing method

Place an appropriate amount of strongly acidic cation exchange resin in a beaker (if

using dry resin, first soak it in saturated sodium chloride solution and then gradually

dilute the solution to prevent the resin from fracturing due to rapid swelling). Rinse

with water until the supernatant is clear. Soak in water for 12 h~24 h to allow for full

swelling. Drain the water, then add 95% ethanol and soak for 24 h. Wash with water

until no odor of alcohol remains. Add hydrochloric acid solution (1+3), soak for 2 h~3

h, and then wash with water until neutral. Add sodium hydroxide solution (100 g/L),

soak for 2 h~3 h, and wash with water until neutral. Finally, rinse with hydrochloric

acid solution (1+3) and soak in it for 24 h, stirring frequently. And then rinse three times

with hydrochloric acid solution (1+3).

Load the treated resin into an exchange column. Wash the resin with 400 mL of

hydrochloric acid solution (1+3) at a flow rate of 10 mL/min. Then, wash with water

until the effluent is neutral. Soak in water and set aside.

A3 Regeneration method

Transfer the exhausted strongly acidic cation exchange resin into a beaker. Rinse it three

times with hydrochloric acid solution (1+3) and let it soak for 24 h, stirring frequently.

Drain the hydrochloric acid solution, then rinse again three times with hydrochloric acid

solution (1+3).

Load the treated resin into the exchange column. Wash the resin with 400 mL of

hydrochloric acid solution (1+3) at a flow rate of 10 mL/min. Then, wash with water

until the effluent is neutral. Soak in water and set aside.

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 10 pages — is available in the English PDF.

Referenced standards

Normative references

ISO 6353 · GB/T 610.2 · ISO 6353.1982 · GB/T 619 · GB 6682 · ISO 3696.1987 · GB/T 9739 · HG 3-1168

Cited by

GB/T 4632-2008Determination of moisture-holding capacity of coal

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