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Pulling Salt Out of Seawater with Magnets

A previously unutilized effect of magnetism observed by Khalifa University’s Dr. Emad Alhseinat may be key to energy-efficient, low-cost seawater desalination and other industrial separation processes.

In a world of dwindling freshwater resources and rising greenhouse gases, researchers are constantly searching for affordable, more sustainable ways to turn seawater into potable drinking water, without further straining the planet’s natural resources or increasing global greenhouse gas emissions.

Now, a team of researchers from Khalifa University’s Center for Membranes and Advanced Technology (CMAT), led by Dr. Emad Alhseinat, Assistant Professor of Chemical Engineering, have discovered a new way to separate salt from saline water that does not rely on the traditional thermal and membrane methods, both of which can be energy intensive and expensive, particularly for small-scale desalination and desalination of low-salinity water.

Instead, Dr. Alhseinat’s membraneless separation method uses electric and magnetic fields to pull salt ions from a stream of saltwater towards a porous electrode, where they are collected and easily removed. The new approach is described in a paper that is currently under review by the journal Electrochemical Acta and is authored by Dr. Alhseinat and Dr. Pei Shui, a Visiting Scholar at Khalifa University. The team has also filed a patent for the novel system titled ‘System and Method for Removing Ions and Dissolved Charged Particles from Saline Water with Magnetic and Electric Fields’ (PCT patent application number is PCT/IB2019/054453).

Research into using electric charges to separate salt ions from seawater – a process known as capacitive deionization, or CDI – is accelerating rapidly. In a paper published earlier this year in The Journal of Physical Chemistry C, Dr. Alhseinat provides a comprehensive overview of the evolving desalination technology and identifies ways to optimize the configuration and electrode components of CDI.

Electric charge separation coupled with magnetic fields, however, is what Dr. Alhseinat believes could lead to a breakthrough in not only seawater desalination, but in many applications that rely on separation, like gas sweetening – the process of removing hydrogen sulfide from natural gas – and removing heavy metals from wastewater.