Today, roughly 700 million people lack access to safe drinking water, and estimates show this figure rising to 1.8 billion in just 10 years.
As of 2016, global municipal water withdrawal comprise 12% of the total global water withdraw, the lifestyle changes at the level of each single citizen can significantly impact water scarcity.
Forward Osmosis (FO) is a membrane-based separation process which uses osmotic pressure difference between a concentrated “draw” solution and a feed stream to drive water through a semi-permeable membrane.
The majority of energy consumption for FO is draw agent regeneration, i.e., separating draw agents and water in the draw stream. Adequate draw agents can substantially reduce the energy cost by reducing the electric energy usage / replacing it with other less expensive forms of energy, including low-grade industrial waste-heat or geothermal sources.
The major challenge for FO is to design novel draw agents that can be efficiently separated from treated water by low-cost thermal energy.
Ionic liquid (IL) draw agents that exhibit lower critical solution temperature (LCST) phase behavior are a promising future direction. These ILs show a high osmotic pressure and low reverse diffusion, and the LCST phase behavior (i.e., decreasing water miscibility with increasing temperature) allows these draw agents to be regenerated straightforwardly by integration with low-cost heat sources.