DEVELOPING MULTIFUNCTIONAL FORWARD OSMOSIS (FO) DRAW SOLUTES FOR SEAWATER DESALINATION

Abstract

Worldwide clean water scarcity has accelerated the development of new technologies for seawater desalination. Among various desalination processes, forward osmosis (FO, also known as direct osmosis) is an attractive and promising one. In an FO process, water in the feed solution at a lower osmotic pressure can pass spontaneously through a semi-permeable membrane to the draw solution at a higher osmotic pressure. Afterwards, the draw solution will undergo a regeneration process, which extracts water from the draw solution and re-concentrates the draw solution for reuse. Compared to reverse osmosis which is widely used desalination technology currently, FO shows advantages of low energy requirement and less serious membrane fouling. Despite the rapid progress in the development of FO draw solutes recently, existing draw solutes still have disadvantages such as low osmotic pressure, high reverse flux, or complex and energy-intensive regeneration method. Moreover, the application of FO in seawater desalination has yet to be investigated with eligible draw solutes. Therefore, the objectives of this project are (1) to develop multifunctional FO draw solutes with high osmolality, low reverse solute flux, and facile?regeneration approaches; and (2) to apply these draw solutes in FO process to investigate their effectiveness especially in seawater desalination. In our study, dendrimer-based electrolyte, Na+ functionalized carbon quantum dots, thermoresponsive copolymer, and thermoresponsive ionic liquid have been proven to be promising FO draw solutes in seawater desalination. Future work will focus on developing multifunctional compounds that can be easily separated from water in response to external stimuli such as heat.