New nanopore zeolite membranes for water treatment

Zeolite membranes have been studied extensively for more than fifteen years, mainly focusing on gas separation and liquid pervaporation processes. Recently, molecular dynamic simulation has shown that zeolite membranes are theoretically suitable for ion removal from aqueous solutions by reverse osmosis (RO) processes. The separation mechanism of the zeolite membranes is the size exclusion of hydrated ions, which have kinetic sizes significantly larger than the aperture of the Hydroxysodalite (HS) zeolite (diameter 0.4 nm). HS zeolite membrane indicates that it may be possible to simultaneously separate ions and dissolved organic compounds from water by RO processes. Zeolite membranes may be used as an alternative to polymeric membranes for desalination of seawater and wastewaters. HS zeolite membranes composed of a continuous intergrowth of HS zeolite crystals have been prepared hydrothermally on the surface of porous tubular supports. In this research, synthesis of zeolite HS membrane was investigated. SEM and XRD analysis have been used to confirm zeolite HS membrane formation. Membrane performance has been evaluated using an experimental pervaporation setup. Effects of operation condition (temperature, rate and pressure) on the membrane structure and performance have been investigated for HS zeolite membranes grown onto seeded mullite supports.