PROPERTIES ON HYBRID SYSTEM OF ION EXCHANGE RESIN AND DYNAMIC MEMBRANE FOR REMOVAL TO ION AQUEOUS SOLUTION

摘要

Dynamic membrane (DM) was first reported in 1966 by workers at the Oak Ridge National Laboratories. DM is a specific type of membrane that can be formed in situ by filtering a solution containing either inorganic or organic materials through a porous support. DM can be classified into two types: self-forming and pre-coated types. The pre-coated membrane is produced by passing a solution of one or more specific components over the surface of a porous support. A self-forming membrane is a dynamic membrane in which the membrane forming materials are the same as those to be separated. The turbulence created at the face of the filtering medium trims down the cake build up and therefore slows down the rate of filtration resistance. The cake or dynamic membrane becomes denser as the filtration progresses and this enables separation of smaller particulates even though the support membrane has a larger pore size. Cake formation is unavoidable in cross flow filtration; however, this phenomenon can be exploited, such as forming a dedicated or purpose built dynamic membrane to enhance filtration. Studies of self-forming dynamic membranes were first emphasized on salt rejections in reverse osmosis process. Because is due to the characteristic to high flux and intermediate salt rejection. However, DM is not used widely by several reasons. These included insufficient salt retention for practical desalting application, the membrane properties were difficult to control reproducible and the flux tended to decline continuously with time after the membrane forming materials were removed. There have been some studies on these types of membranes for the purpose of microfiltration (MF) in wastewater treatment in recent years.