This innovation may reduce the cost of water desalination
Electronics360 News Desk | August 07, 2019A team of scientists has developed design rules to make “thermally responsive” ionic liquids for use in separating water from salt. The innovation could help reduce the cost of desalination.
Ionic liquids are liquid salts that bind to water. The researchers said this makes them useful in forward osmosis to separate contaminants from water.
Thermally responsive ionic liquids may be an even better solution, they said, as these liquids use thermal energy rather than electricity, which is required by conventional reverse osmosis (RO) desalination for the separation.
The study, published in the journal Nature Communications Chemistry, studied the chemical structures of several types of ionic liquid/water to determine what “recipe” would work best.
“The cost of RO desalination driven by electricity is prohibitive,” said Robert Kostecki, of the Lawrence Berkeley National Laboratory. “Our study shows that the use 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 large fraction of costs."
The researchers said it was long thought that an effective ionic liquid separation relied on the overall ratio of organic components (parts of the ionic liquid that are neither positively or negatively charged) to its positively charged ions. The Berkeley Lab team learned that the number of water molecules an ionic liquid can separate from seawater depends on the proximity of its organic components to its positively charged ions.
This unexpected result led to rules of design regarding which atoms in ionic liquids are most critical in desalination.
Because forward osmosis uses heat instead of electricity, the thermal energy can be provided by renewable sources such as geothermal and solar or industrial low-grade heat.
Also contributing to the study were researchers from the University of California-Berkeley and Idaho National Laboratory. The work was supported by the Department of Energy’s Office of Energy Efficiency and Renewable Energy.
