Separating salts from seawater can be realized via evaporation and
concentration, cooling crystallization, reverse osmosis technologies,
etc. These technologies have been applied in many areas including desalination,
liquid desiccant, and sewage disposal [1–4]. However, due to
the existing technology constrains, the driving heat source temperature
for these technologies normally exceeds 100 °C, i.e. the water boiling
temperature. Double-effect lithium bromide absorption air conditioning,
for example, needs driving heat source temperature over 130 °C.
Ultra-low grade heat in the temperature range of 50–100 °C, which is
abundant from renewable energy and waste heat sources, has not
been effectively utilized [5]. Therefore, exploring efficient methods of
salt-water separation which uses ultra-low grade heat becomes increasingly
appealing from a sustainable perspective.