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Superhydrophobic Coating for Evaporative Purification and Minerals Extraction

Oak Ridge National Laboratory

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PDF Document Publication12-G00204_2744_2400.pdf (845 KB)

Technology Marketing SummaryResearchers at ORNL are using their superhydrophobic coating technology to tackle the age-old problem of obtaining potable water. In the process, they have
also developed a cost-effective method to extract industrial minerals and metals such as potassium, lithium, and magnesium from the seas and other waters.
Potable water is becoming an increasingly scarce resource. Evaporative desalination is one of the cheapest, easiest, simplest ways to covert salt or brackish
water into fresh water. Unfortunately, huge salt deposits are created during the process. These deposits form a hard, well-bonded coating on exposed surfaces
that must be regularly removed to keep the operation efficient and commercially viable. The required cleaning not only takes a lot of time, effort, and energy,
but also requires large amounts of fresh water. Because of this, evaporative desalination has all but been abandoned commercially in the United States—
until now.DescriptionORNL’s superhydrophobic (SH) coatings amplify a liquid’s surface tension, creating a microscopic layer of air on the SH surface that inhibits water contact with the treated surface. Simple hydrophobic coatings create no such air layer and therefore don’t perform as well. A drop of ocean water on an SH treated surface will ball up and roll around like a marble. As the water evaporates and crystals start to form, the crystals don’t adhere to the treated surface and are easily removed. ORNL scientists have successfully demonstrated the technology with treated containers filled with ocean water. The crystals so formed also contain solidified minerals.

Applying ORNL’s SH coatings to all flat, curved, tubular, and other surfaces at least partially in contact with contaminated liquids or the contaminants themselves will greatly simplify maintenance of desalination equipment and significantly reduce salt contamination and resulting corrosion of surrounding structures and support equipment. The process can also be used for extracting minerals and metals from ocean and brackish waters separate from or combined with production of potable water.
  • Environmentally friendly
  • Little to no hazardous waste
  • Easy to apply and scalable
  • More durable than traditional superhydrophobic coatings
  • Low cost
Applications and Industries
  • Purification of salt and brackish waters
  • In-field military water purification systems
  • Corrosion inhibition for desalination equipment and support structures
  • Materials separation/mineral extraction
  • Anti-fouling coatings
More InformationJohn T. Simpson, Steve R. McNeany, Thomas V. Dinsmore, Scott R. Hunter, and Ilia N Ivanov. Superhydrophobic Coated Apparatus for Liquid Purification by Evaporative Condensation, U.S. Patent Application 13/030,535, filed February 18, 2011.

John T. Simpson and Scott Hunter. Harvesting Dissolved Minerals and Salts from Ocean Water, application in preparation.
Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Patent 8,668,812
Superhydrophobic coated apparatus for liquid purification by evaporative condensation
Disclosed are examples of apparatuses for evaporative purification of a contaminated liquid. In each example, there is a first vessel for storing the contaminated fluid. The first vessel includes a surface coated with a layer of superhydrophobic material and the surface is at least partially in contact with the contaminated liquid. The contaminants do not adhere to the surface as the purified liquid evaporates, thus simplifying maintenance of the apparatus.
Oak Ridge National Laboratory 03/11/2014
Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
UT-B ID 201102744, 201002400DevelopmentAvailable08/21/201208/21/2012

Contact ORNL About This Technology

To: Alexander G. DeTrana<>