(379c) Tunable Membranes for Water Applications – an Overview

The engineering advancement of separation processes with reduced energy consumption and minimal environmental impact is critical for sustainable operation. Membrane processes are finding wide applications ranging from water treatment to catalysis to advanced bio-separations. The development of tunable, nanocomposite membranes provide added opportunities in residence time control (through permeate flux) and responsive characteristics.  Traditional MF membrane pores can be functionalized with single covalently-attached polypeptides and for the creation of LbL (layer-by-layer) assembly for NF type water related separations.  Example membranes are: PVDF, PVP coated polycarbonate (PC), nylon-based anhydride activated membranes, Polyethylene-silica (PE-silica) composite membranes, alumina membranes, and cellulosic membranes.  The dependence of conformation properties of polyelectrolytes/polypeptides on pH also provides tunable separations and membrane flux control. Layer-by-layer (LBL) assembly technique, most commonly conducted by intercalation of positive and negative polyelectrolytes or polypeptides, is a powerful, versatile and simple method for assembling  nano-structures in pores. Non-stoichiometric immobilization of charged polyelectrolyte assemblies within confined pore geometries leads to an enhanced volume density of ionizable groups in the membrane pores. The presentation will include: (1) pore functionalization approaches, (2) tunable NF type separations, and (3) toxic pollutant separations from water.  The authors would like to acknowledge the financial support of NIEHS-SBRP and NSF-IGERT program for this work.