Method for determining pore diameter of ultra-filtration membrane

Abstract

The invention relates to a method for determining the pore diameter of an ultra-filtration membrane. According to the method provided by the invention, a brand-new driving pressure generation manner is adopted based on an existing liquid-liquid displacement principle and aiming at a driving pressure in displacement liquid; measurement and obtaining aiming at a high-precision value of the driving pressure of the ultra-filtration membrane are realized by measuring two parts including a pressure for pushing the displacement liquid and a pressure aiming at a membrane pore of the ultra-filtration membrane by the displacement liquid, so as to further directly improve the determination precision which finally aims at the pore diameter of the ultra-filtration membrane. The method for determining the pore diameter of the ultra-filtration membrane provided by the invention is convenient to realize based on the prior art and has the practical and effective effects on the improvement of the determination precision of the pore diameter of the ultra-filtration membrane.

Description

technical field [0001] The invention relates to a method for measuring the pore size of an ultrafiltration membrane. Background technique [0002] There are many methods for measuring membrane pore size, such as liquid flow rate method, mercury injection method, electron microscope method, gas adsorption and desorption method, bubble pressure method and osmotic porosity method, etc. or less disadvantages. Among them, when the liquid flow rate method is used to measure the pore size of the membrane, the porosity of the membrane needs to be determined in advance. This method is mainly suitable for microfiltration membranes. If it is used to measure the pore size of ultrafiltration membranes, it may cause distortion of the measurement results; It is a void hole, not all "active holes" that penetrate the membrane, and the required test pressure is relatively high, which may easily cause the deformation of the sample and make the result untrue; the electron microscope method is ...

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Problems solved by technology

[0002] There are many methods for measuring membrane pore size, such as liquid flow rate method, mercury injection method, electron microscope method, gas adsorption and desorption method, bubble pressure method and osmotic porosity method, etc. or less disadvantage

Among them, when the liquid flow rate method is used to measure the pore size of the membrane, the porosity of the membrane needs to be determined in advance. This method is mainly suitable for microfiltration membranes. If it is used to measure the pore size of ultrafiltration membranes, it may cause distortion of the measurement results; It is a void hole, not all "active holes" that penetrate the membrane, and the required test pressure is relatively high, which may easily cause the deformation of the sample and make the result untrue; the electron microscope method is more intuitive, but it is a destructive test, and can only get Local information; the gas adsorption and desorption method measures the void pores, which is different from the through-hole of the separation membrane, and is not suitable for the determination of the pore size of the ultrafiltration membrane; the bubble pressure method (also known as the gas permeation method) is limited to the measurement of the membrane The maximum pore size of the pores, the pressure required for the determination of small pore ultrafiltration membranes is much higher than the operating pressure of the membrane, so it is generally considered only suitable for the determination of microfiltration membranes

The liquid-liquid displacement method using the two-phase equilibrium and osmotic properties in the membrane pores belongs to the displacement detection technology, which can directly measure the pore diameter of the membrane pores, but this method also has disadvantages: the pressure-driven pressure supply method in the measurement process uses a peristaltic pump. The flow rate in the measurement process is small and the required driving pressure is high. Therefore, the flow rate is small and the operating pressure is high, so that the reading swing of the pressure gauge severely affects the pressure measurement result and the determination of the flow rate, so that the size of the final membrane pore size is the same as The actual value is quite different

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