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First, the preservation of waterproof and breathable membrane
When the film is stored for a long time, it must maintain good performance. The external energy has use value, so the life of the waterproof and breathable film is an important issue. Therefore, special attention should be paid to the actual storage.
The storage of waterproof and breathable microfiltration membranes can be divided into two methods: wet storage and dry storage. Either way, the purpose is to prevent membrane hydrolysis, to prevent the growth and erosion of microorganisms, and to shrink and deform the membrane.
① Wet storage
The key to wet preservation is to keep the membrane surface wet with preservation solution. The following formula can be used for the preservation solution: water: glycerol: formaldehyde = 79.5: 20: 0.5. The role of formaldehyde is to prevent the breeding and reproduction of microorganisms on the surface of the membrane and prevent erosion of the membrane. The purpose of adding glycerin is to lower the freezing point of the preservation solution and prevent damage to the membrane due to freezing. The formaldehyde in the formula can also be replaced by other bactericidal agents that do not harm the membrane such as copper sulfate. The storage requirement of cellulose acetate membrane is temperature 5 ~ 40 ℃, PH = 4.5 ~ 5, while the temperature and pH of non-cellulose acetate membrane can be kept wider.
② dry preservation
Waterproof and breathable microfiltration membranes are often provided on the market as dry membranes because they are easy to store and transport. In addition, if the wet film is to be stored dry, it must be processed by the following method. The specific method is: the cellulose acetate film can be soaked with 50% glycerol aqueous solution or 0.1% sodium dodecylsulfonate aqueous solution for 5-6 days, and dried at a relative humidity of 88%. For polysulfone membrane, 10% glycerin, sulfonated oil, polyethylene glycol and other solutions can be used as dehydrating agent and dried at room temperature. In addition, the surfactant also has a good effect on the deformation of the protective film pores.
Matters needing attention in the maintenance and maintenance of waterproof and breathable membrane systems
Membrane system maintenance and maintenance should pay attention to the following issues.
① Depending on the membrane, special attention should be paid to the environment in which it is used, especially the temperature, pH value of the liquid, and even the chlorine in the liquid.
② When the membrane system is stopped for a short time, pay attention to the moisture retention of the membrane, because once the membrane surface loses water and there is no remedial measure, the waterproof and breathable membrane holes will shrink and deform, which will reduce the membrane performance.
③ When stopping, avoid contact with high-concentration material liquid.
④ Regularly wash and maintain the membrane with a maintenance solution to reduce membrane pollution.
⑤ In use, operate according to the operating conditions that the membrane system can withstand, and avoid long-term overload operation to avoid irrecoverable damage to the membrane.