GB/T 34709-2017 English PDF (GB/T34709-2017)

GB/T 34709-2017: General test method for silica gel
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GB/T 34709-2017
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 71.060.01
G 10
General test method for silica gel
ISSUED ON: NOVEMBER 01, 2017
IMPLEMENTED ON: MAY 01, 2018
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of PRC;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Test methods ... 5 
3.1 General provisions ... 5 
3.2 Determination of particle size ... 5 
3.3 Determination of percent of pass of particle size ... 6 
3.4 Determination of wear rate ... 8 
3.5 Determination of compacted bulk density ... 12 
3.6 Loose density ... 13 
3.7 Determination of adsorption capacity ... 15 
3.8 Identification of color change ... 18 
3.9 Determination of pore volume ... 18 
3.10 Determination of heating loss ... 21 
3.11 Determination of ignition loss ... 22 
3.12 Determination of the percent of pass of spherical particles ... 23 
3.13 Determination of silica content ... 23 
3.14 Determination of iron content ... 25 
3.15 Determination of chloride content ... 27 
3.16 Determination of pH ... 27 
3.17 Determination of specific resistance ... 28 
3.18 Determination of specific surface area ... 28 
3.19 Determination of cobalt chloride content ... 28 
3.20 Determination of carbon dioxide adsorption capacity ... 30 
3.21 Determination of particle strength ... 30 
3.22 Determination of the rate of non-burst in contact with water ... 31 
Appendix A (Informative) Standard operating method for typical instruments for
the determination of BET specific surface area ... 32 
Appendix B (Informative) Standard operating method-1 for typical instruments
for the determination of carbon dioxide adsorption ... 34 
Appendix C (Informative) Standard operating method-2 for typical instruments
for the determination of carbon dioxide adsorption ... 36 
General test method for silica gel
1 Scope
This standard specifies the test methods for silica gel series products.
This standard applies to the series product such as type-A silica gel, type-C
silica gel, microsphere silica gel, color-changing silica gel, indicator silica gel,
type-B silica gel, pressure-swing-adsorption silica gel, FNG water-resistant
silica gel, cat-litter silica gel, additive silica gel, macro-porous silica gel.
2 Normative references
The following documents are essential to the application of this document. For
the dated documents, only the versions with the dates indicated are applicable
to this document; for the undated documents, only the latest version (including
all the amendments) are applicable to this standard.
GB/T 3049-2006 Chemical products for industrial use - General method for
determination of iron content - 1,10-Phenanthroline spectrophotometric
method
GB/T 6003.1-2012 Test sieves - Technical requirements and testing - Part 1:
Test sieves of metal wire cloth
GB/T 6003.2-2012 Test sieves - Technical requirements and testing - Part 2:
Test sieves of metal wire cloth
GB/T 6682-2008 Water for analytical laboratory use - Specification and test
methods
GB/T 13390-2008 Metallic powder - Determination of the specific surface
area - Method of nitrogen adsorption
HG/T 3696.2 Inorganic chemicals for industrial use - Preparations of
standard and reagent solutions for chemical analysis - Part 2: Preparations
of standard solutions for impurity
HG/T 3696.3 Inorganic chemicals for industrial use - Preparations of
standard and reagent solutions for chemical analysis - Part 3: Preparations
of reagent solutions
3.3.2.2 Test sieve of metal perforated plate: The series of test sieves as
specified in GB/T 6003.2-2012, which is equipped with a sealing cover and a
receiving tray. It is used for the determination of spherical silica gel.
3.3.3 Analytical procedures
Install two sieves which have mesh sizes respectively equivalent to the upper
limit and lower limit of the particle size as agreed between both parties and
receiving trays sequentially (the general range of particle size of the spherical
silica gel is: 1 mm ~ 3 mm; 2 mm ~ 5 mm; 4 mm ~ 8 mm. The general range of
particle size of the bulk silica gel is: 0.5 mm ~ 2 mm; 1 mm ~ 6 mm; 2 mm ~ 8
mm). According to the particle size of the product, select the following
operations:
a) For products which have a particle size of above 250 μm (60-mesh), weigh
50 g ~ 100 g of specimen, accurate to 0.1 g. Place it in the upper limit
sieve. Cover the sealing cover. Use hand to hold it. Shake it horizontally
and circumferentially for 1 min. The total number of shaking is 60 ~ 70.
The amplitude of shaking is about 20 cm. Weigh the specimen amount in
the lower limit sieve, accurate to 0.1 g.
b) For products which have a particle size of 250 μm (60-mesh) and below,
weigh approximately 20 g of specimen, accurate to 0.1 g. Place it in the
upper limit sieve. Use a brush to gently brush the specimen. Brush it whilst
sieving it. After about 30 min, weigh the specimen amount in the lower
limit sieve, accurate to 0.1 g.
3.3.4 Calculation of results
The percent of pass of particle size is expressed by mass fraction w1 and
calculated by the formula (1):
Where:
m1 - The mass of the specimen in the lower limit sieve, in grams (g);
m - The mass of the specimen, in grams (g).
Take the arithmetic mean of the results of parallel determinations as the
determination result. The absolute difference between the results of two parallel
determination is not more than 2.0%.
3.4.2.3 Analytical procedures
Take approximately 25 mL of the specimen. Use a 425 μm test sieve (for
products of 300 μm ~ 850 μm) or a 250 μm test sieve (for products of 125 μm
~ 425 μm). Carry out sieving according to the method as specified in 3.3. Place
about 10 mL of specimen which remains on the sieve into a 50 mL beaker.
Uniformly pour the specimen from the beaker into a glass measuring device
which is equipped with a glass funnel within about 1 min. Take about (10 ± 0.1)
mL. Open the disc collision object 5 and the metal mesh 6 of the guiding
fountain-bed. Pour the specimen into the guiding fountain-bed. Install it well.
Turn on the air compressor, to allow the air to flow through the humidifier and
flowmeter. At the airflow rate of (15 ± 0.5) L/min, blow-grind it for 30 min.
Remove the nozzle 4. Take out the specimen. Use a 300 μm test sieve (for
products of 300 μm ~ 850 μm) or a 125 μm test sieve (for products of 125 μm
~ 425 μm) to sieve it. Use the same method as above to measure the volume
of the sieve residue, accurate to 0.1 mL.
3.4.2.4 Calculation of results
The wear rate is expressed by mass fraction w3 and calculated by the formula
(3):
Where:
V - The volume of the specimen, in milliliters (mL);
V1 - The volume of the sieve residue after blow-grinding, in milliliters (mL).
Take the arithmetic mean of the results of parallel determinations as the
determination result. The absolute difference between the results of two parallel
determinations is not more than 3%.
3.5 Determination of compacted bulk density
3.5.1 Summary of method
Stack the weighed specimen into a container of a certain volume. Use the
specified method to vibrate-compact it. Read the volume of the specimen. Make
calculation.
3.5.2 Instruments and equipment
Glass measuring cylinder: A measuring cylinder which has a capacity of 100 mL
and an inner diameter of (25 ± 2) mm as well as a glass base.
3.7 Determination of adsorption capacity
3.7.1 Static adsorption method
3.7.1.1 Summary of method
Place a certain amount of dried specimen in a closed container of a certain
relative humidity. Make it achieve adsorption equilibrium. Then weigh the
specimen. Calculate the amount of adsorption.
3.7.1.2 Reagents
Sulfuric acid solution: Use sulfuric acid and water to prepare sulfuric acid
solution of different concentrations according to Table 1, to air of different
relative humidity.
Table 1
3.7.1.3 Instruments and equipment
3.7.1.3.1 Electrothermal constant-temperature drying oven: The temperature
can be controlled at 170 °C ~ 190 °C.
3.7.1.3.2 Closed containers: Glass dryers for general laboratory use.
3.7.1.4 Analytical procedures
Heat and dry the specimen at 170 °C ~ 190 °C for 2 h. Weigh about 0.3 g ~ 0.5
g of specimen. Quickly place it in a weighing bottle which has been dried at
170 °C ~ 190 °C to a constant mass. Spread it flatly and uniformly as practical
as possible. Immediately apply the stopper tightly. Place it in a desiccator. Cool
it to room temperature. Accurately weigh it, accurate to 0.0002 g. Follow the
Table 1 to prepare sulfuric acid solution of different concentrations (the amount
of sulfuric acid solution used is more than 100 mL per specimen). Respectively
place it in a series of closed containers. Keep the relative humidity in the closed
container at 20%, 50%, 90% (or other relative humidity as required by the
standard). Place the weighing bottle which has the weighed specimen into the
compartment of closed container. Open the weighing bottle’s stopper. Hold it at
(25 ± 2.5) °C for 48 hours. Remove and immediately tighten the stopper. Weigh
it, accurate to 0.0002 g.
3.7.1.5 Calculation of results
Relative humidity / %
Concentration of sulfuric acid / %
Relative density of
water solution
~ 2 h, until the weight gain does not exceed 0.001 g.
3.7.2.5 Calculation of results
The adsorption capacity is expressed by mass fraction w7 and calculated by the
formula (7):
Where:
m1 - The mass of specimen after adsorption equilibrium, in grams (g);
m - The mass of specimen, in grams (g).
Take the arithmetic mean of the results of parallel determinations as the
determination result. When the relative humidity of the air is 20%, the difference
between the results of two parallel determinations is not more than 1.0%. When
the relative humidity of the air is 35% ~ 50%, the difference between the results
of two parallel determinations is not more than 1.5%. When the relative humidity
of the air is 80%, the difference between the results of two parallel
determinations is not more than 2.0%.
3.8 Identification of color change
3.8.1 Summary of method
The color of specimen as displayed after reaching the adsorption equilibrium at
different relative humidity of the air is compared with the indicated
chromatogram.
3.8.2 Determination procedures
Compare the specimen as measured according to 3.7 or the specimen which
reaches adsorption equilibrium at the corresponding relative humidity with the
specified indicator chromatogram. The color of the specimen shall meet the
requirements of the corresponding color scale or expression.
3.9 Determination of pore volume
3.9.1 Water titration method
3.9.1.1 Summary of method
Take a specimen of a certain particle size. Add water dropwise. When the
The pore volume w8 is expressed in mL/g and calculated according to formula
(8):
Where:
V - The volume of water consumed, in milliliters (mL);
m - The mass of specimen, in grams (g).
Take the arithmetic mean of the results of parallel determinations as the
determination result. The absolute difference between the results of two parallel
determinations is not more than 0.02 mL/g.
3.9.2 Nitrogen adsorption method
3.9.2.1 Summary of method
Use the specific surface porosity meter to measure the adsorption isotherm at
relative pressure (P/P0) of the sample at the liquid nitrogen temperature, that is,
use the BET method to determine the specific surface process. According to
Kelvin's theory, when P/P0 > 0.35, pore coagulation will begin to appear; when
P/P0 > 0.99, the pores of silica gel are basically full. According to the adsorption
capacity, it may calculate the pore volume of sample.
3.9.2.2 Instruments and equipment
Specific surface porosity tester: It is equipped with high-purity nitrogen.
3.9.2.3 Analytical procedures
Weigh 0.2 g ~ 0.3 g of specimen which has been dried to a constant mass,
accurate to 0.0002 g. Put it into the measuring tube. At 150 °C ~ 200 °C,
vacuum-degas it for 2 h, to make the vacuum degree drop below 1 Pa. Start
measuring the adsorption isotherm. For the initial determination, it requires
starting the dead volume correction. When the pore volume is specially
determined, the setting points of relative pressure (P/P0) may be concentrated
between 0.35 and 0.995. It may also continue the BET method to determine the
specific surface process, to continue the relative pressure (P/P0) to 0.995. Then
end the measurement. According to the measured adsorption isotherm, use the
volume of liquid nitrogen as adsorbed corresponding to the relative pressure
(P/P0) of 0.995 to calculate the total pore volume. Use the value of the pore
volume per unit mass as the pore volume, in the unit of mL/g. For the typical
instrument operation, see Appendix A.
The instrument uses a program-controlled halogen lamp/infrared lamp for
temperature-rise to heat the sample. Make continuous automatic weighing, until
the mass is constant. Report the results.
3.10.2.2 Instruments and equipment
Rapid moisture analyzer: Halogen/infrared heating type, which has a weighing
accuracy of 0.001 g.
3.10.2.3 Analytical procedures
Spread approximately 2 g ~ 10 g of specimen in the drying tray of the rapid
moisture analyzer. Set the drying temperature, to control it at (150 ± 5) °C
(120 °C ± 5 °C for blue silica gel indicator and color-changing silica gel); 170 °C
~ 190 °C for fine-pored silica gel). Enter the mass of specimen. Start the
determination program. At the end of determination, the instrument
automatically reports the results.
Take the arithmetic mean of the results of parallel determinations as the
determination result. The absolute difference between the results of two parallel
determinations is not more than 0.5%.
3.11 Determination of ignition loss
3.11.1 Instruments and equipment
3.11.1.1 High-temperature furnace: The contr...