Novel platform purifies oil-contaminated seawater

The United Nations' most recent Intergovernmental Panel on Climate Change report paints a bleak picture for the world's water supply: Of the 7.8 billion people on Earth, about 4 billion do not have access to sufficiently clean water for at least a month every year. While several water purification schemes have been proposed, they consistently fail at some critical point-typically, they are not stable, big or hardy enough for real-world applications, according to researchers based at Technical Institute of Physics and Chemistry, Chinese Academy of Sciences and Xiamen University in China who may have cracked the problem.

On March 22 in Nano Research, the researchers reported the details of a new platform that uses sunlight to purify seawater with high energy efficiency compared to other similar approaches (above 90%) while also avoiding common pitfalls.

"There is a tremendous demand for freshwater in households and for industrial, agricultural and other applications, so various water purification technologies have been developed to alleviate the shortage of freshwater resources," said paper author Miao Wang, Xiamen University's College of Materials. "Comparing the pathways, solar-driven purification of seawater or contaminated water via interfacial evaporation is promising as a low-cost system."

Such purification approaches use sunlight to heat water at its surface, evaporating the liquid and separating the polluted or salty counterparts from the water molecules, which then escape into the air as vapor to enter the natural cycle of condensation to become clean, consumable water. The problem, according to paper author Xu Hou, Xiamen University's College of Chemistry and Chemical Engineering, and College of Physical Science and Technology, is that attempts to scale this approach for real-world application have been hindered by oil contamination, instability, salt-crystallization and complicated fabrication processes.