Desalination of salt solutions by means of circulating diffusion dialysis system using salinity gradient energy

In this paper, a novel desalination system called circulating diffusion dialysis (CDD) was set up by connecting two stacks using salt bridges, with the stacks consisting of cation-, and anion-exchange membranes and three types of water flow channels of two salt solutions (HS: high salt concentration, LS: low salt concentration) and desalting water (DW) solution. By feeding 30,000 mg/dm3 NaCl as HS and various initial concentrations of NaCl as LS and DW to the CDD system, the salt concentration of DW decreased to less than 500 mg/dm3. In conclusion, we confirmed that the CDD system can desalinate saline water without applying any heat and electrical power from outside; but just by feeding salt solutions with different concentrations into the system.