On the other side, particles that are smaller than the membrane pore will go through, as the membrane is very thin, it cannot produce adsorption capacity to those particles. Although the supporting layer is relatively thick, as the hole is bigger than the membrane pore, it also cannot produce adsorption capacity either. In this case, only the effect of filtering out remains, so it is easy for backwashing.
When referring to the oil in the water, because of the instability, the oil drop which is larger than the membrane pore will not be always filtered out. It may split into drops that are smaller than the membrane pore and go through. Although they can go through the membrane, as they may coalesce into big oil drops and be adsorbed by the micropore in the supporting layer.
Determination of Bubble Point
Determination of the bubble point pressure is a crucial method to ensure the quality of the membrane. It can reflect the pore size of the microporous membrane filter, which is closely related to the quality of the filtered liquid. The operators could select the most suitable membrane for the samples to be tested and acquire a highly accurate testing result in the end.
Prevention From Rupture
First of all, correctly distinguish the front side (facing down) and the reverse side (facing up) of the membrane filter, otherwise, it will be easily blocked by impurities and decrease the filtration speed.
Secondly, when the temperature is low, the treated membrane filter should be immersed in the injection water that is kept with the same temperature as the liquid medicine for 5 to 10 minutes.
In this way, the tensile strength of the membrane filter will not be decreased because of the temperature difference, which could avoid the rupture or cracking phenomenon.
Also, to preventing this situation, the same size filter paper or crepe cloth could be used by putting them on the membrane filter. However, it is necessary to boil the crepe cloth with a concentration of 20g·L -1 sodium sulfonate for about 30 min, then clean it with the injection water.