Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard was proposed by and is under the jurisdiction of SAC/TC 382 National Technical Committee on Separation Membrane of Standardization Administration of China.
Determination of pore size for porous membranes -
Standard particle method
1 Scope
This standard specifies the principle, reagent, instrument and method of determining the pore size for porous membranes following standard particle method.
This standard is applicable to the determination of the average pore size of hollow fiber, plate and tubular porous membranes.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 6682 Water for analytical laboratory use - Specification and test methods
GB/T 20103-2006 Technical terms for membrane separation
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 20103-2006 and the following apply. For easy reference, some terms and definitions specified in GB/T 20103-2006 are listed below.
3.1
membrane
thin barrier with certain physical or chemical properties on the surface, which makes a discontinuous interval between two adjacent fluid phases and affects the rate of penetration of the components of the fluid
[GB/T 20103-2006, Definition 2.1.1]
3.2
porous membrane
membrane with porous and open structure
[GB/T 20103-2006, Definition 2.1.19]
3.3
pore size
nominal diameter of membrane pore
[GB/T 20103-2006, Definition 2.1.31]
3.4
mean pore size
average size of membrane surface pore
[GB/T 20103-2006, Definition 5.1.6]
3.5
standard particle
spherical particle with particle size distributed in a concentrated and uniform way and the physical and chemical properties stable, which can be used as a “measuring tool” for measuring the pore size of porous membranes
3.6
crossflow membrane process
separation process in which pressure drives the feed material to flow parallel to the membrane surface (tangential flow) and the permeate to pass vertically through the membrane (vertical flow)
Note: It is revised from Definition 2.2.9 in GB/T 20103-2006.
3.7
retention
ability to remove specific components
Note: It is revised from Definition 2.1.35 in GB/T 20103-2006.
4 Test principle
A series of standard particle test solutions of different particle sizes were prepared to test the retention of porous membrane with regard to standard particles with different particle sizes, plot the particle size-retention curve, and take the particle size of the standard particle corresponding to a retention of 90% as the mean pore size of the porous membrane.
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5 Reagents and instruments
5.1 Reagents
The main reagents are as follows:
——Water: Grade III water specified in GB/T 6682, or water with a purity higher than that of Grade III water;
——Standard particle: particle size standard reference material with reference material number (see Annexes A and B), as well as ordinary particle or fluorescent particles which are determined by test to have a relative standard deviation of particle size of less than 10% or a particle size dispersion index of less than 0.25.
5.2 Apparatus and instruments
The main apparatus and instruments required for the test are as follows:
a) Porous membrane testing device, equipped with water bath, pump, pressure gauge, thermostat, etc. See Figure C.1 in Annex C for schematic diagram;
b) Analytical balance, with a sensitivity of 0.1 mg;
c) Scattered light turbidimeter: with an accuracy of 0.01 NTU;
d) Fluorescence spectrophotometer: with a fluorescence value resolution of 0.01;
e) Pressure gage: with an accuracy of Grade 0.4;
f) Thermometer: with a measuring range of 0℃~50℃ and an accuracy of 0.1℃.
6 Test procedures
The test procedures for the mean pore size of porous membranes are as follows:
a) Prepare three pieces of membrane samples from the membrane to be tested, and wash them with water for later use.
b) Prepare a dispersion liquid with a mass concentration of (10±1) mg/L using standard particles of appropriate size, and use it as the test solution for pore size evaluation of porous membrane.
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c) Place one piece of the membrane sample prepared in Procedure a) in the membrane testing device connected as shown in Figure C.1, and add the test solution into the thermostatic water bath.
d) Operate the membrane testing device by crossflow membrane process to reduce the effect of concentration polarization on membrane surface, with the test solution temperature adjusted to (25±0.5)℃, the transmembrane pressure adjusted to 0.10 MPa, and the membrane surface flow velocity in the test system to no less than 0.25 m/s; and then collect the filtered and feed solutions after the system operates stably for 5 min.
e) Determine the mass concentration of standard particles in the filtered and feed solutions respectively following method specified in Annex D.
f) Perform the parallel test following Procedures b)~e) with the other two pieces of membrane samples prepared in Procedure a).
g) Calculate the retention using Equation (1) and take the average of the values obtained from three parallel tests as the test result. The relative standard deviation of the retentions obtained from the three parallel tests shall not exceed 10%.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Test principle
5 Reagents and instruments
6 Test procedures
7 Test report
Anne A (Informative) National class I particle size reference materials
Annex B (Informative) National class II particle size reference materials
Annex C (Normative) Porous membrane test device
Annex D (Informative) Method for testing mass concentration of standard particles
Annex E (Informative) Example for the test of mean pore size for porous membranes
Bibliography
