Reasons why ultrafiltration membrane cannot remove calcium and magnesium ions from water

      Ultrafiltration membrane has strong filtration and purification treatment effect, mainly used to retain harmful substances in water, while keeping the pH value of produced water unchanged. If you want to remove calcium and magnesium ions, it is recommended to use nanofiltration membrane or reverse osmosis membrane.

      Membrane treatment can generally be divided into ultrafiltration, nanofiltration and reverse osmosis. You refer to the ultrafiltration membrane, the general pore size is 0.1-0.01um, the molecular weight of retention do 1000 - 300,000 between. The diameter and molecular weight of calcium and magnesium ions are much smaller than that value. Therefore, for through the ultrafiltration membrane.　

      1. The concept of ultrafiltration

　　Application of pore size of 1.0 ~ 20.0nm or larger ultrafiltration membrane to filter solutions containing large molecules or fine particles, so that the large molecules or fine particles from the solution separation process is called ultrafiltration.

　　2. Characteristics of ultrafiltration

　　Similar to reverse osmosis, the driving force of ultrafiltration is also the pressure difference, which is pressurized on the solution side to make the solvent pass through the membrane and get separated. Unlike reverse osmosis, in the process of ultrafiltration, small molecules of solute will pass through the ultrafiltration membrane together with the solvent.

　　3. The essence of ultrafiltration

　　The essence of ultrafiltration is sieving, particle adsorption and clogging in the micropores on the membrane surface.

　　Ultrafiltration membrane is asymmetric membrane, its surface active layer has a pore size of 10-9 ~ 2 × 10-8m micropores, can retain the relative molecular weight of 500 or more macromolecules and colloidal particles, the pressure difference used is 0.1 ~ 0.5MPa.

　　However, ultrafiltration reverse osmosis membrane can remove the scaling core in water such as colloids, which can reduce the degree of scaling to a certain extent.

　　4. Advantages of ultrafiltration membrane

　　Due to the pollution of water sources and secondary pollution is quite serious, it is difficult to achieve the effect of deep purification of drinking water with ordinary filtration media. Ultra-filtration membrane purification technology uses high-precision pure physical filtration principle, without adding any chemical substances, relying on ultra-filtration membrane surface dense micropores for sieving, thus retaining harmful substances, so as to achieve the effect of filtration and purification.

       Through various reasons, the development of membrane making technology and the scale of production have made the performance of ultrafiltration membrane more stable. However, ultrafiltration membrane is not the mainstream technology for removing calcium and magnesium ions from water