HEORETICAL AND EXPERIMENTAL INVESTIGATIONS FOR MEMBRANE POTENTIAL IN A NOSYMMETRICAL AND POROUS MEMBRANE

摘要

Two interesting features can be considered about NF membranes [1]. First, NF membranes possess molecular weight cut-off (MWCO) of about 200-1000, which is intermediate between conventional reverse osmosis (RO) membranes and ultrafiltration (UF) membranes [2]. Therefore, it is possible to assume that the pore diameters range from 1 nanometer to a few nanometer from the Stokes-Einstein relationship. Another feature is that most of them are charged either positively or negatively due to their materials. Hence, charge effects (steric effects and Donnan effects) may play some major roles in the separation achieved [3]. In addition, NF can be operated at low pressure (usually range from 0.5 to 3MPa), which will be very attractive in reducing capital and operation costs and will provide easier system maintenance.