Basic Chemistry and Physics of MF/ UF Membranes and Their Precursors
The distinction between microfiltration (MF) or ultrafiltration (UF) lies primarily in the size distribution of the membrane pores. The MF/UF membrane chemistry can be modified to improve performance in targeted applications. The common membrane modification strategies involve: addition of a compatible modifier into the casting solution; adsorption of a modifier on to the membrane surface; chemical or physicochemical post-treatments of the surface; and/or grafting or cross-linking a modifier on the surface. Postformation modifications are sometimes performed by practitioners without access to the membrane formation technology and equipment. In melt casting, multicomponent melts are used as membrane precursors. Lacquers and melts are very similar in many respects and can both be viewed as "dense polymer systems". The molecular aspects of liquid membrane precursors are amenable to characterization by the powerful radiation scattering techniques of polymer physics. An important indicator of an MF/UF membrane functionality is its hydraulic transmembrane flux.