New desalination technology converts sea water into fresh water at lower cost

Traditional RO desalination utilizes extremely high pressure to force polluted or salty water through a dense, semi-permeable polymer film. The pressurized water molecules pass through the pores of the membrane, leaving salt ions and impurities trapped in the film, resulting in purified water.

According to civil and environmental engineering assistant professor Eric Hoek, who led the research team that developed the new RO method, traditional RO can be costly because the polymer film becomes soiled quickly, and a high volume of energy is required to force the water through the membrane.

Hoek's new RO device uses a unique cross-linked matrix of polymers and engineered nanoparticles that draws in water ions and repels nearly all contaminants. The new membrane is built on the nanoscale to create tiny tunnels that draw water and allow it to flow through much easier than contaminants.

"The nanoparticles are designed to attract water and are highly porous, soaking up water like a sponge, while repelling dissolved salts and other impurities," Hoek said. "The water-loving nanoparticles embedded in our membrane also repel organics and bacteria, which tend to clog up conventional membranes over time."

Hoek's new membranes require less energy to pump water through them, and since the membranes repel particles that stick to traditional RO surfaces, they become soiled less quickly. The new RO membranes are as effective as current RO methods, but are less expensive and more productive, Hoek said. Initial tests on the membranes suggest they could reduce the expense of desalinating water by up to 25 percent.

Hoek said the world is in great need of a supply of affordable, sustainable clean water. "It is essential that we reduce the overall cost of desalination -- including energy demand and environmental issues -- before a major draught occurs and we lack the ability to efficiently and effectively increase our water supply."

Hoek is currently working with partner NanoH2O, LLP, to develop the patent-pending technology. The new RO technology should be commercially available within the next two years.

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