As populations increase and chronic droughts persist, coastal cities like Carlsbad in Southern California have increasingly turned to sea desalination to supplement dwindling freshwater supply. Now scientists at (Berkeley Lab) the Department of Energy’s Lawrence Berkeley National Laboratory investigating how to make desalination less expensive have hit on promising design guidelines 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 ahead osmosis to separate contaminants from water. (See Berkeley Lab Q&A, “Moving Ahead 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 brand new Berkeley Lab research, published lately within the journal Nature Communications Chemistry, studied the chemical structures of a number of sorts of ionic liquid/water to determine what “recipe” would work best.
“The present state-of-the-art in RO desalination works very well. However, the price of RO desalination driven by electricity is prohibitive,” mentioned Robert Kostecki, co-corresponding author of the research. “Our research shows that the usage of low-cost “free” heat—such as geothermal or solar heat or industrial waste heat generated by machines—combined with thermally responsive ionic liquids could offset a big fraction of prices that go into current RO desalination technologies that solely depend on electrical energy.”