GB/T 38949-2020Determination of pore size for porous membranes - Standard particle method (English PDF)

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.

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.

5 Reagents and instruments

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.

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)°C, 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%.