포스텍과 MIT가 만든 단비같은 소식

Abstract

A shortage
of fresh water is one of the acute challenges facing the world today.
An energy-efficient approach to converting sea water into fresh water
could be of substantial benefit, but current desalination methods
require high power consumption and operating costs or large-scale
infrastructures, which make them difficult to implement in
resource-limited settings or in disaster scenarios. Here, we report a
process for converting sea water (salinity ~500 mM or ~30,000 mg l⁻¹)
to fresh water (salinity <10 mM or <600 mg l⁻¹) in
which a continuous stream of sea water is divided into desalted and
concentrated streams by ion concentration polarization, a phenomenon
that occurs when an ion current is passed through ion-selective
membranes. During operation, both salts and larger particles (cells,
viruses and microorganisms) are pushed away from the membrane (a
nanochannel or nanoporous membrane), which significantly reduces the
possibility of membrane fouling and salt accumulation, thus avoiding two
problems that plague other membrane filtration methods. To implement
this approach, a simple microfluidic device was fabricated and shown to
be capable of continuous desalination of sea water (~99%
salt rejection at 50% recovery rate) at a power
consumption of less than 3.5 Wh l⁻¹, which is comparable to
current state-of-the-art systems. Rather than competing with larger
desalination plants, the method could be used to make small- or
medium-scale systems, with the possibility of battery-powered operation.