Ion sieving and desalination: Energy penalty for excess baggage

Journal Article · Mon Apr 03 00:00:00 EDT 2017 · Nature Nanotechnology

DOI:https://doi.org/10.1038/nnano.2017.53· OSTI ID:1363990

Devanathan, Ram ^[1]

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1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Here, more than a billion people do not have access to clean water globally and millions of people die every year from water borne diseases. Human activity has resulted in depletion of groundwater, seawater intrusion in coastal aquifers, pollution of water resources, ecological damage, and resultant threats to the world’s freshwater, food supply, security, and prosperity. To address this challenge, there is a pressing need to produce clean water from seawater, brackish groundwater, and waste water. Current desalination methods are energy intensive and produce adverse environmental impact. At the same time, energy production consumes large quantities of water and creates waste water that needs to be treated with further energy input. Water treatment with membranes that separate water molecules from ions, pathogens and pollutants has been proposed as an energy-efficient solution to the fresh water crisis. Recently, membranes based on carbon nanotubes, graphene and graphene oxide (GO) have garnered considerable interest for their potential in desalination. Of these, GO membranes hold the promise of inexpensive production on a large scale but swell when immersed in water. The swollen membrane allows not only water molecules but also ions, such as Na⁺ and Mg²⁺, to pass through. Abraham and coworkers show that the interlayer spacing in a GO laminar membrane can be tuned to a certain value and then fixed by physically restraining the membrane from swelling. When the authors reduced the spacing systematically in steps from 9.8 Å to 7.4 Å, the ion permeation rate was reduced by two orders of magnitude while the water permeation rate was only halved.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC05-76RL01830
• OSTI ID: 1363990
• Report Number(s): PNNL-SA-124040
• Journal Information: Nature Nanotechnology, Vol. 12, Issue 6; ISSN 1748-3387
• Publisher: Nature Publishing Group
• Country of Publication: United States
• Language: English

Related Subjects

77 NANOSCIENCE AND NANOTECHNOLOGY
36 MATERIALS SCIENCE
graphene oxide
desalination
membrane