Smart draw agents for emerging forward osmosis application

Forward osmosis (FO) membrane technology has attracted rapidly growing research interest because it shows great potential in reducing energy consumption and costs in water desalination and treatment. The lack of a suitable draw agent has been identified as a challenging problem in the commercial implementation of FO technology. Recent years have seen significant advances in the development of smart draw agents with responsive properties, from which water can be recovered under different stimuli. This review highlights the properties and performance of some interesting smart draw agents reported recently, including functionalized magnetic nanoparticles, thermo-responsive polyelectrolytes, and stimuli-responsive polymer hydrogels.