New way to recover pure water from highly concentrated salt solutions


Researchers developed a new way to recover water from highly concentrated salt solutions. The system will alleviate water shortages in arid regions and reduce concerns surrounding high salinity brine disposal, such as hydraulic fracturing waste.

recover pure water

David Jassby, from UCR’s Bourns College of Engineering, said, the research involves the development of a carbon nanotube-based heating element that will vastly improve the recovery of fresh water during membrane distillation processes.

Osmosis is the most common method of removing salt from seawater, wastewater, and brackish water.

It is not capable of treating highly concentrated salt solutions such solutions called brines, are generated during reverse osmosis and hydraulic fracturing.

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In the case of hydraulic fracturing, produced water is often disposed of underground in injection wells.

Thermal desalination technology can treat brine is membrane distillation, in which heat drives water vapor across a membrane, allowing further water recovery while the salt stays behind.

However, hot brines are highly corrosive, making the heat exchangers and other system elements expensive in traditional membrane distillation systems, because the process relies on the heat capacity of water, single pass recoveries are quite low, leading to complicated heat management requirements.

To improve on this, the researchers developed a self-heating carbon nanotube-based membrane that only heats the brine at the membrane surface.

The new system reduced the heat needed in the process and increased the yield of recovered water to close to 100 percent.

The insights of the study will allow carbon nanotube-based heating elements to be used in other applications where electrochemical stability of the nanotubes is a concern.

More information: [Nature]