Separation Characteristics of CSM Reverse Osmosis Membranes in Their Application Processes

CSM reverse osmosis membranes are a type of aromatic polyamide composite membrane (TFC membrane) with a three-dimensional cross-linked surface active layer developed by Sehan Corporation. As we know, the active layer and support layer of a reverse osmosis composite membrane are made of different materials and are formed using interfacial polymerization. The bottom layer of the CSM reverse osmosis membrane is a polyester nonwoven fabric support structure, and before membrane synthesis, its surface is first pressed into a solid, smooth, and non-loose fibrous structure using a calender, with a thickness of approximately 100 micrometers. The support layer (intermediate layer) of the CSM membrane is a polysulfone polymer cast onto the polyester nonwoven fabric, with a thickness of approximately 40 micrometers. Together, these two layers form the robust support layer of the CSM composite membrane. Therefore, the CSM reverse osmosis membranes provided by Sehan Corporation have a high resistance to external mechanical pressure and chemical degradation during application. The final surface active layer of the CSM reverse osmosis membrane, formed through interfacial polymerization, has a three-dimensional cross-linked aromatic polyamide structure with a thickness of approximately 0.2 micrometers. The total membrane thickness of the CSM reverse osmosis membrane elements provided by Sehan is approximately between 140 and 150 micrometers.

Sehan's CSM reverse osmosis membrane elements are manufactured and rolled using a world-class automated production line, ensuring stable performance, uniform water flow channel thickness, and even water distribution during use. Furthermore, the fully automated production process ensures precise cutting length, bonding positions, and adhesive dosage during membrane element rolling, maximizing the effective usable area of each Sehan membrane element. High-quality, high-performance materials combined with modern automated production technology guarantee users high-quality CSM reverse osmosis membrane elements.

Due to Sehan's fundamental changes in CSM reverse osmosis membrane manufacturing technology, CSM reverse osmosis membranes exhibit superior performance in desalination rate, water flux, pressure resistance, fouling resistance, and membrane performance stability, placing them among the world's leading products. Currently, CSM reverse osmosis membranes, with their superior quality and reasonable price, have become the preferred choice for domestic engineering companies and water treatment equipment users. Comparison of separation characteristics of CSM reverse osmosis membranes in application:

1) Generally, inorganic substances are separated more easily than organic substances, but the separation and removal effects are also very good for organic substances with a molecular weight greater than 100.

2) Electrolytes dissolved in water are separated more easily than non-electrolyte substances.

3) When separating electrolytes, the higher the charge of the substance being separated, the better the separation effect (i.e., trivalent ions are separated better than divalent ions; similarly, divalent ions are separated better than monovalent ions).

4) The removal effect of inorganic ions is affected by their specific hydrated ion number and hydrated ion radius—the larger the hydrated ion radius, the easier it is for inorganic ions to be removed.

5) When separating non-electrolytes, larger molecules are easier to separate.

6) Gases in the solution easily pass through the membrane, therefore the removal rates of substances such as ammonia, chlorine, carbon dioxide, oxygen, and hydrogen sulfide are relatively low. 7) The removal rate of weak acids is low, which is also related to the molecular weight of the acid being separated—that is, as the molecular weight decreases, the membrane's separation effect becomes worse. The removal rates of organic acids by the membrane are in the following order: citric acid > tartaric acid > acetic acid. The separation characteristics of CSM reverse osmosis membranes are as described above. In engineering practice, our understanding of solute separation characteristics should comprehensively consider factors such as the selective adsorption of the solute and the membrane, electrostatic interactions, and hydrogen bonding.