Polyvinylpyrrolidone pvpk30 water treatment membrane

Hollow fiber ultrafiltration membrane is the most mature and advanced form of ultrafiltration technology. The outer diameter of hollow fiber is 0.4-2.0mm, the inner diameter is 0.3-1.4mm, and the wall of hollow fiber tube is covered with microholes, and the pore size can be expressed by the molecular weight of the intercepted material, and the molecular weight of the intercepted material can reach thousands to hundreds of thousands. In the function of hollow fiber membrane, the pore diameter and size of the membrane are closely related to the pore-making agent. At present, PVPK30 is the most used. As a better pore-causing agent, PVPK30 mainly affects the pore structure from two factors: thermodynamics and kinetics.

Thermodynamics affects the pore structure

When the content of PVPK30 in the casting liquid is low, the influence of thermodynamic factors becomes the dominant factor. The addition of PVPK30 reduces the thermodynamic stability of the casting liquid system and the gel rate is faster. At the same time, PVPK30 has hydrophilicity, which accelerates the exchange of solvent and non-solvent in the film forming process, and the structure of the film becomes more loose, the opening rate increases, the water flux increases, and the retention rate decreases.

Kinetics affects the pore structure

When PVPK30 increased to a certain extent, the viscosity of the liquid system of the cast film increased with the increase of the concentration of PVPK30, resulting in the increase of the solvent-non-solvent exchange resistance, the influence of kinetic factors became the dominant factor, the development of finger pores in the film was inhibited, the water flux decreased, and the retention rate increased.