Nanofiltration Technology

Nanofiltration (NF) is a novel separation technology. The Hangzhou Water Treatment Center pioneered its development in China in the 1990s. Nanofiltration membranes exhibit two significant characteristics in their separation applications: firstly, their molecular weight cutoff is between that of reverse osmosis and ultrafiltration membranes, ranging from 200 to 2000; secondly, nanofiltration membranes have a certain cutoff rate for inorganic salts because their surface separation layer is composed of a polymeric dielectric, which has electrostatic interactions with ions. Structurally, most nanofiltration membranes are composite membranes, meaning that the chemical composition of the surface separation layer and its supporting layer differs. Based on the first characteristic, it is speculated that the surface separation layer of nanofiltration membranes may possess a microporous structure of approximately 1 nm, hence the name "nanofiltration."

Characteristics of nanofiltration technology:

① The membrane structure is mostly a multi-layered, loose structure;

② The separation process involves no chemical reactions, requires no heating, involves no phase transition, does not destroy bioactivity, and does not alter flavor or aroma.

Application areas:

• Separation and purification of oligosaccharides;

• High-concentration concentration of fruit juice;

• Isolation of peptides and amino acids;

• Concentration and purification of antibiotics;
  

• Concentration of milk and whey protein;
  

• Comprehensive utilization of agricultural products;
  

• Development of membrane bioreactors.