As populations boom and chronic droughts persist, coastal cities like Carlsbad in Southern California have increasingly turned to ocean desalination to supplement a dwindling fresh water supply. Now scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) investigating how to make desalination less expensive have hit on promising design rules for making so-called “thermally responsive” ionic liquids to separate water from salt.
Ionic liquids are a liquid salt that binds to water, making them useful in forward osmosis to separate contaminants from water. (See Berkeley Lab Q&A, “Moving Forward on Desalination”) Even better are thermally responsive ionic liquids as they use thermal energy rather than electricity, which is required by conventional reverse osmosis (RO) desalination for the separation. The new Berkeley Lab study, published recently in the journal Nature Communications Chemistry, studied the chemical structures of several types of ionic liquid/water to determine what “recipe” would work best.