Industrial Nanofiltration

Nanofiltration Technology Overview: Nanofiltration is a cross between ultrafiltration and reverse osmosis membrane separation technology between the nanofiltration membrane separation layer has a porous structure surface of about 1nm, it is called "NF." Nanofiltration exhibit their separation applications the following salient features: 1. nanofiltration process is usually carried out at room temperature, no phase change and chemical reaction, without destroying biological activity, heat-sensitive material suitable for the separation, concentration and purification. 2. nanofiltration membrane molecular weight cutoff between reverse osmosis and ultrafiltration, nanofiltration is generally believed that molecular weight cutoff of 200 to 1000, is particularly suitable for molecular size substances 1nm or more, for example, lactose, maltose, antibiotics, synthetic drugs, etc. small organic molecules. 3. Most of the charged nanofiltration membrane, since the charge effects on ion selective, even at low operating pressure, still bivalent and multivalent ions have a higher retention rate, while the monovalent ions The rejection rate is low. The nanofiltration membrane separation process with microfiltration, ultrafiltration, reverse osmosis membrane separation process, the pressure difference is the driving force, the driving force of the general control of nanofiltration 0.5 ~ 2.0MPa. 5. From a structural point of view, mostly composite nanofiltration membrane separation or chemical composition of the surface layer of the film and its supporting layer are different. Common Nanofiltration performance parameters: flux GFD, gallons per day per square foot; LMH, liters of water per square meter per hour capacity GPD, gallons per day; GPM, gallons per minute; m3 / D, cubic meters per day system recovery W % filtrate flow / feed flow rate × 100% rejection of a substance X%, (1- the concentration of a substance in the filtrate / concentration of a substance in the concentrate) × 100% of a substance transmittance Y%, the concentration of a substance in the filtrate / dope concentration of a substance × 100% volume concentration ratio VCR, initial feed solution volume / volume trapped dope solution osmotic pressure π, ion molar concentration × × gas constant thermodynamic temperature