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Rice University’s desalination technology for hypersaline brine features a central passage for heated brine that is sandwiched between two membranes. A stainless steel heating element produces fresh, salt-free water by driving water vapor through each membrane. A coating of the 2D nanomaterial hexagonal boron nitride (hBN) protects the heating element from the highly corrosive brine. Credit: Kuichang Zuo/Rice University

A thin coating of the 2-D nanomaterial hexagonal boron nitride is the key ingredient in a cost-effective technology developed by Rice University engineers for desalinating industrial-strength brine.

More than 1.8 billion people live in countries where fresh water is scarce. In many arid regions, seawater or salty groundwater is plentiful but costly to desalinate. In addition, many industries pay high disposal costs for wastewater with high salt concentrations that cannot be treated using conventional technologies. Reverse osmosis, the most common desalination technology, requires greater and greater pressure as the salt content of water increases and cannot be used to treat water that is extremely salty, or hypersaline.

Hypersaline water, which can contain 10 times more salt than seawater, is an increasingly important challenge for many industries. Some oil and gas wells produce it in large volumes, for example, and it is a byproduct of many desalination technologies that produce both freshwater and concentrated brine. Increasing water consciousness across all industries is also a driver, said Rice's Qilin Li, co-corresponding author of a study about Rice's desalination technology published in Nature Nanotechnology.