Solar water desalination

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Nanophotonics-enabled solar membrane distillation for off-grid water purification
Pratiksha D. Dongare, Alessandro Alabastri, Seth Pedersen, Katherine R. Zodrow, Nathaniel J. Hogan, Oara Neumann, Jinjian Wu, Tianxiao Wang, Akshay Deshmukh, Menachem Elimelech, Qilin Li, Peter Nordlander and Naomi J. Halas
PNAS July 3, 2017. 114 (27) 6936-6941; published ahead of print June 19, 2017.
Contributed by Naomi J. Halas, May 16, 2017 (sent for review February 2, 2017; reviewed by Svetlana V. Boriskina and Amy Childress)

Current desalination technologies provide solutions to the increasing water demands of the planet but require substantial electric energy, limiting their sustainable use where conventional power infrastructure may be unavailable. Here, we report a direct solar method for desalination that utilizes nanoparticle-assisted solar vaporization in a membrane distillation geometry. This scalable process is capable of providing sufficient clean water for family use in a compact footprint, potentially for off-grid desalination at remote locations.


With more than a billion people lacking accessible drinking water, there is a critical need to convert nonpotable sources such as seawater to water suitable for human use. However, energy requirements of desalination plants account for half their operating costs, so alternative, lower energy approaches are equally critical. Membrane distillation (MD) has shown potential due to its low operating temperature and pressure requirements, but the requirement of heating the input water makes it energy intensive. Here, we demonstrate nanophotonics-enabled solar membrane distillation (NESMD), where highly localized photothermal heating induced by solar illumination alone drives the distillation process, entirely eliminating the requirement of heating the input water. Unlike MD, NESMD can be scaled to larger systems and shows increased efficiencies with decreased input flow velocities. Along with its increased efficiency at higher ambient temperatures, these properties all point to NESMD as a promising solution for household- or community-scale desalination. end quote

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