Pressure Retarded Osmosis Performance of Polydopamine Modified Thin Film Composite Membrane of Differing Selectivity and Structure

摘要

Many osmotically driven membrane processes (ODMPs) are for water treatment application whether they be direct osmotic concentration for wastewater management, osmotic dilution for fertigation, or forward osmosis for water purification and desalination [1]. As a result the latest generation of commercial thin film composite membranes for ODMPs have been engineered for good performance at lower operating pressures than membranes typically used for pressure driven separations. While this does not imply these membranes unsuitable for high pressure applications an understanding of membrane interactions with pressure may suggest future deviations in ODMP membrane design between low and high pressure applications. One ODMP which does employ high transmembrane pressures is called pressure retarded osmosis (PRO) [2]. PRO is an alternative energy technology harnessing the latent energy of concentration gradients where a low concentration feed solution is in contact with a higher concentration draw solution under a hydrostatic pressure less than its osmotic pressure. The resulting osmosis causes the draw solution to experience a constant pressure volumetric expansion capable of doing work. Many PRO studies consider the open-loop PRO process, in which seawater serves as draw solution to concentrate river water [3].