Zeolite-Polyamide Nanocomposite Membranes for Sea-Water Desalination

Many exciting and new advanced materials concepts have been proposed for preparing better performing desalination membranes including aligned-carbon nanotubes, protein-polymer hybrids, zeolite-coated ceramics, chlorine-tolerant sulfonated and fluorinated polymers, and inorganic-organic nanocomposites. Following a brief introduction to the state of the art in nanocomposite desalination membranes, this presentation will focus on recent developments related to “thin film nanocomposite” (TFN) reverse osmosis (RO) membrane materials. Previously, it has been hypothesized that zeolite addition increased membrane permeability through molecular sieving action.  In this talk, we will discuss the impacts of zeolite molecular sieve pore size and hydration state on the performance and physical-chemical properties of TFN membranes designed for use in seawater desalination. We will present extensive characterization results that suggest molecular sieving only partly explains the TFN membranes’ higher water permeability and suggest that polyamide film structure (i.e., crosslinking) is different for zeolite containing polyamide films. From these results we hypothesize new insights into the mechanisms by which zeolite nanoparticles influence the observed separation performance of zeolite-polyamide TFN membranes.