(61b) New and Novel Materials for Membrane Separations

Synthetic membranes are important for many separation applications, such as the separation and purification of atmospheric gases for medical and industrial use, and salt removal from seawater in regions lacking fresh water sources. Unlike mesh filters used to separate large solid particles from a fluid (phase difference), membranes used to separate molecular species from one another (i.e., a chemical separation), is a much more difficult process [given the size scale and level of mixing of the components].

            Because of the benefits of membrane-based chemical separations over other methods (e.g., smaller device footprints, lower energy use compared to distillation), there has been recent interest in applying membranes to new separation problems, as well as improving membrane materials used in existing separations.  Consequently, there is a need for better membrane materials in general (i.e., with better selectivity, better productivity, longer life and operational stability, increased operating temperature range, use in chemically challenging environments, and the ability to adjust materials properties and performance for a given application). 

The new materials are room temperature ionic liquids (RTILs), zeolites and lyotropic liquid crystals (LLCs).  Each of these materials has unique physiochemical properties that provide an advantage in certain applications.  Each of these materials will be discussed and their use in gas and water treatment.

For researchers working on the design of new membrane materials, it is important to not only consider the design factors that afford better separation selectivity but to also consider the other factors that afford good productivity as well.  Often it is these materials engineering factors that decide whether a membrane material is viable in practical separation or not.