Ultrafiltration is a sieving process related to the pore size of the membrane. The pressure difference between the two sides of the membrane is used as the driving force, and the ultrafiltration membrane is used as the filter medium. Under a certain pressure, when the original liquid flows through the membrane surface, the ultrafiltration The many fine pores densely covered on the membrane surface only allow small molecules of water to pass through and become the permeated liquid, while the material in the original solution with a volume larger than the pore size of the membrane surface is trapped on the inlet side of the membrane and becomes a concentrated solution. The purpose of purification, separation and concentration of the original liquid.
Generally speaking, the separation systems of ultrafiltration membranes are all water-phase systems. The surface of the hydrophilic membrane forms hydrogen bonds with water to make it in an ordered structure. When the hydrophobic solute is close to the surface of the ultrafiltration membrane, this ordered structure must be broken, which is obviously not easy to proceed, so the surface of the ultrafiltration membrane is not easily contaminated. The water on the surface of the ultrafiltration membrane has no hydrogen bonding effect, and the approach of the hydrophobic solute to the surface of the ultrafiltration membrane is a spontaneous process of increasing entropy, so the ultrafiltration membrane is easily contaminated by the hydrophobic solute. The hydrophilicity and hydrophobicity of the ultrafiltration membrane can be measured by the surface contact angle. The small contact angle indicates that the hydrophilicity is good.