Seawater desalination by gas hydrate process and removal characteristics of dissolved ions (Na+, K+, Mg2 +, Ca2 +, B3 +, Cl−, SO42 −).

In order to evaluate hydrate-based desalination (HBD), experiments with seawater samples were carried out at various conditions (i.e. hydraulic pressure, washing step, and hydrate-forming gas). Before and after the hydrate process, cations (Na + , K + , Mg 2 + , Ca 2 + , and B 3 + ) and anions (Cl − and SO 4 2 − ) were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) and ion chromatography (IC). In a single stage of CO 2 hydrate process without any pretreatment, 71%–94% of each cation was removed in the following order: K + > Na + ≈ Mg 2 + ≈ Ca 2 + > B 3 + and 73%–83% of each anion was removed. When the brines on the surface of hydrate pellets were removed, the ion removal efficiency increased above 4%. It was also found that the desalting efficiency depended on the hydrate-forming gas (CO 2 > CH 4 ) and the hydraulic pressure (6–10 MPa) to produce hydrate pellets. In this study, the removal efficiency of cations and anions in a real seawater sample using HBD processes were reported for the first time. [ABSTRACT FROM AUTHOR]